Display device

Abstract

To provide a semiconductor device having a capacitor element having a high opening ratio and capable of increasing a charge capacity, and provide a semiconductor device capable of reducing consumption power.SOLUTION: A display device has: a transistor including a semiconductor film with a light-transmitting property; a capacitor element having a dielectric film provided between a pair of electrodes; an insulating film provided on the semiconductor film with a light-transmitting property; and a first light-transmitting conductive film provided on the insulating film. The capacitor element has: the first light-transmitting conductive film functioning as one electrode; the insulating film functioning as a dielectric; and a second light-transmitting conductive film facing the first light-transmitting conductive film through the insulating film and functioning as the other electrode. The second light-transmitting conductive film is a metal oxide film including a dopant that is formed on the same surface as the semiconductor film with a light-transmitting property of the transistor.SELECTED DRAWING: Figure 15

Description

[Technical field]

[0001] The invention disclosed in this specification and elsewhere relates to a semiconductor device. [Background technology]

[0002] In recent years, flat panel displays such as liquid crystal displays (LCDs) have become widespread. In a display device such as a flat panel display, the pixels are arranged in the row and column directions. In the pixel, a transistor which is a switching element and an electric A liquid crystal element is connected in series with the liquid crystal element, and a capacitance element is connected in parallel with the liquid crystal element. do.

[0003] The semiconductor material constituting the semiconductor film of the transistor is amorphous. Silicon semiconductors such as silicon or polysilicon (polycrystalline) are widely used.

[0004] Metal oxides that exhibit semiconductor properties (hereinafter, referred to as oxide semiconductors) are used in transistors. It is a semiconductor material that can be applied to the semiconductor film of the following: zinc oxide or In-Ga-Zn system oxide Techniques for fabricating transistors using nitride semiconductors have been disclosed (Patent Document 1 and Patent Document 2). See reference 2.)

[0005] In order to increase the aperture ratio, a metal oxide film is provided on the same surface as the oxide semiconductor film of the transistor. The oxide semiconductor film and the pixel electrode connected to the transistor are provided at a predetermined distance from each other. A display device having such a capacitive element has been disclosed (see Patent Document 3). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2007-123861 A [Patent Document 2] JP 2007-96055 A [Patent Document 3] U.S. Pat. No. 8,102,476 Summary of the Invention [Problem to be solved by the invention]

[0007] The capacitance element has a pair of electrodes and a dielectric film between them. The other electrode is a gate electrode, a source electrode, a drain electrode, or the like that constitutes a transistor. In many cases, the light-shielding conductive film is used.

[0008] In addition, the larger the capacitance of the capacitance element, the more the liquid crystal element will dissipate when an electric field is applied. The period during which the orientation of the crystal molecules can be kept constant can be extended. In a display device in which the period can be extended, the number of times that image data is rewritten can be reduced. This makes it possible to reduce power consumption.

[0009] However, when one electrode of the capacitor is formed of a semiconductor film, the semiconductor film is Depending on the potential applied, the capacitance value charged to the capacitance element may be lower than the specified value. As a result, the period during which the alignment of the liquid crystal molecules in the liquid crystal element is kept constant becomes shorter, and the rewriting frequency of image data becomes shorter. The number of devices increases, and power consumption increases.

[0010] In order to increase the charge capacity of the capacitance element, the area occupied by the capacitance element is increased. Specifically, there is a method for increasing the area where a pair of electrodes overlap. In the above display device, a light-shielding layer is provided to increase the area where the pair of electrodes overlap. If the area of ​​the conductive film to be covered is increased, the aperture ratio of the pixel is reduced, and the display quality of the image is degraded.

[0011] In view of the above problems, one aspect of the present invention provides a liquid crystal display device having a high aperture ratio and an increased charge capacity. Another object of the present invention is to provide a semiconductor device having a capacitor that can be An object of the present invention is to provide a semiconductor device capable of reducing power consumption. [Means for solving the problem]

[0012] One embodiment of the present invention is a transistor including a light-transmitting semiconductor film and a semiconductor device between a pair of electrodes. A capacitor element provided with a dielectric film, an insulating film provided on a light-transmitting semiconductor film, and a first light-transmitting conductive film provided on the insulating film. a first light-transmitting conductive film functioning as an electrode, and the insulating film functioning as a dielectric; The second electrode faces the first light-transmitting conductive film with the insulating film interposed therebetween and functions as the other electrode. The second light-transmitting conductive film is a conductive film having a second light-transmitting property. A metal oxide film containing a dopant is formed on the same surface as the light-transmitting semiconductor film of the transistor. It is a compound film.

[0013] A light-transmitting semiconductor film included in a transistor is formed using an oxide semiconductor. Oxide semiconductors have a large energy gap of 3.0 eV or more, and are highly sensitive to visible light. In this specification, the transparent material included in the transistor has a large transmittance. Metal oxides that exhibit semiconductor properties, such as semiconductor films with optical properties, are described as oxide semiconductors. In addition, the second light-transmitting conductive film included in the capacitor exhibits conductive characteristics. The film is described as a metal oxide.

[0014] The second light-transmitting conductive film serving as the other electrode of the capacitor element is A semiconductor film formed in a step of forming a semiconductor film included in the By adding cesium, the electrical conductivity can be increased, resulting in a metal oxide film with conductive properties. For example, hydrogen, boron, nitrogen, fluorine, aluminum, phosphorus, arsenic, indium, One or more dopants selected from tin, antimony and rare gas elements are implanted by ion implantation or can be added to the semiconductor film by ion doping or the like, or The dopant can also be added by exposing the material to plasma containing the above-mentioned element. The conductivity of the second light-transmitting conductive film which is the other electrode of the capacitor element is 10 S / cm or more. The viscosity is at most 1000 S / cm, preferably at least 100 S / cm and at most 1000 S / cm.

[0015] In addition, in the capacitor, the dielectric film is a light-transmitting semiconductor film included in the transistor. Since the insulating film provided on the insulating film is used, the insulating film can have the same layer structure as the insulating film. For example, an insulating film provided on a semiconductor film included in a transistor may be an oxide insulating film or a nitride insulating film. When the insulating film is laminated, the dielectric film of the capacitance element is a laminate of an oxide insulating film and a nitride insulating film. The structure may be:

[0016] In addition, in the capacitor, an insulating film provided over a semiconductor film included in a transistor is formed by etching. In the case of forming an oxide insulating film and a nitride insulating film, the capacitance element is formed after forming the oxide insulating film. By removing the oxide insulating film only from the area where the oxide insulating film is to be removed, the dielectric film of the capacitance element is made into a single layer of the nitride insulating film. In other words, the nitride insulating film can be used as the other electrode of the capacitance element. The second conductive film having a light-transmitting property is in contact with the second conductive film having a light-transmitting property. The semiconductor film is formed at the same time as the light-transmitting semiconductor film included in the transistor. The semiconductor film is in contact with the nitride insulating film, and thus the nitride insulating film and the semiconductor film Defect levels (interface levels) are formed at the interface. When a semiconductor film is formed by a deposition method or a sputtering method, the semiconductor film is exposed to plasma and oxygen vacancies are generated. Furthermore, nitrogen and / or hydrogen contained in the nitride insulating film migrate to the semiconductor film. When hydrogen contained in the nitride insulating film enters the defect level or oxygen vacancy, the carrier As a result, the conductivity of the semiconductor film increases, it becomes n-type, and the conductivity In other words, a metal oxide film having conductor properties can be formed. In addition, since the thickness of the dielectric film can be reduced, the charge capacity of the capacitance element can be increased. It is possible to do so.

[0017] From the above, in the capacitance element, by adopting a structure in which the nitride insulating film is in contact with the semiconductor film, A dopant that increases the conductivity is added to the semiconductor by ion implantation or ion doping. The process of adding to the film can be omitted, the yield of the semiconductor device can be improved, and the manufacturing cost can be reduced. can be reduced.

[0018] Note that a semiconductor film included in a transistor is an oxide semiconductor film, and an oxide insulating film and a nitride insulating film are When the laminated structure of the insulating film is an insulating film provided on the semiconductor film, the oxide insulating film is a nitrogen It is preferable that the material has a barrier property against nitrogen, that is, is difficult to permeate the material.

[0019] In this way, nitrogen is added to the oxide semiconductor film, which is a semiconductor film included in the transistor. The diffusion of either or both of hydrogen and silicon can be suppressed, thereby suppressing the fluctuation of the electrical characteristics of the transistor. It is possible.

[0020] Note that when the first light-transmitting conductive film is connected to a transistor, The conductive film functions as a pixel electrode.

[0021] When the first light-transmitting conductive film functions as a pixel electrode, the capacitance line is parallel to the scanning line. The other electrode of the capacitance element (the second electrode) extends in the direction of the scanning line and is provided on the same surface as the scanning line. The light-transmitting conductive film is used when forming a source electrode or a drain electrode of a transistor. The insulating film is electrically connected to the capacitance line by a conductive film formed at the same time.

[0022] In addition, the capacitance line is not limited to being extended in a direction parallel to the scanning line and being provided on the same surface as the scanning line. First, the signal line including the source electrode or drain electrode of the transistor extends in a direction parallel to the signal line, and The other electrode of the capacitance element (the second light-transmitting conductive material) is provided on the same surface as the signal line. The conductive film may be electrically connected to the conductive film.

[0023] In addition, the capacitor line is formed using a second light-transmitting conductive film included in the capacitor element. Good too.

[0024] Furthermore, the capacitance line may be connected to each of the capacitance elements included in a plurality of adjacent pixels. In this case, a capacitance line may be provided between adjacent pixels.

[0025] In addition, the second light-transmitting conductive film may be connected to the transistor. The first light-transmitting conductive film functions as a pixel electrode, and the second light-transmitting conductive film functions as a common electrode. It functions as a pole and a capacitance wiring.

[0026] With the above structure, the capacitor element has a light-transmitting property, and therefore the transistor in the pixel Therefore, the aperture ratio can be increased. As a result, a semiconductor device having an improved display quality can be obtained. Thus, a semiconductor device having such a structure can be obtained.

[0027] A light-transmitting capacitor element can be manufactured by utilizing a manufacturing process for a transistor. One electrode of the capacitance element is formed of a conductive film having a light transmitting property, which functions as a pixel electrode or a common electrode. The other electrode of the capacitor may be formed by a process including a step of forming a first insulating film on the first electrode of the transistor. Therefore, the semiconductor film included in the transistor and The other electrode of the capacitance element is made of the same metal element. A process for forming an insulating film provided on a semiconductor film included in a transistor can be used.

[0028] Note that a manufacturing method of a semiconductor device according to one embodiment of the present invention is also Included in. Effect of the Invention

[0029] According to one embodiment of the present invention, there is provided a semiconductor device having a capacitor element with an increased aperture ratio and an increased charge capacity. In addition, a semiconductor device with low power consumption can be provided. do. [Brief description of the drawings]

[0030] [Figure 1]1A to 1C are a diagram illustrating a semiconductor device which is one embodiment of the present invention and a circuit diagram illustrating a pixel. [Diagram 2] FIG. 1 is a top view illustrating a semiconductor device according to one embodiment of the present invention. [Diagram 3] 1 is a cross-sectional view illustrating a semiconductor device according to one embodiment of the present invention. [Figure 4] FIG. 1 is a top view illustrating a semiconductor device according to one embodiment of the present invention. [Diagram 5] 1 is a cross-sectional view illustrating a semiconductor device according to one embodiment of the present invention. [Figure 6] 1A to 1C are cross-sectional views illustrating a method for manufacturing a semiconductor device according to one embodiment of the present invention. [Figure 7] 1A to 1C are cross-sectional views illustrating a method for manufacturing a semiconductor device according to one embodiment of the present invention. [Figure 8] 1A to 1C are cross-sectional views illustrating a method for manufacturing a semiconductor device according to one embodiment of the present invention. [Figure 9] 1 is a cross-sectional view illustrating a semiconductor device according to one embodiment of the present invention. [Figure 10] 1 is a cross-sectional view illustrating a semiconductor device according to one embodiment of the present invention. [Figure 11] FIG. 1 is a top view illustrating a semiconductor device according to one embodiment of the present invention. [Figure 12] FIG. 1 is a top view illustrating a semiconductor device according to one embodiment of the present invention. [Figure 13] FIG. 1 is a top view illustrating a semiconductor device according to one embodiment of the present invention. [Figure 14] FIG. 1 is a top view illustrating a semiconductor device according to one embodiment of the present invention. [Figure 15] 1 is a cross-sectional view illustrating a semiconductor device according to one embodiment of the present invention. [Figure 16] 1A to 1C are cross-sectional views illustrating a method for manufacturing a semiconductor device according to one embodiment of the present invention. [Figure 17] 1A to 1C are cross-sectional views illustrating a method for manufacturing a semiconductor device according to one embodiment of the present invention. [Figure 18] FIG. 1 is a top view illustrating a semiconductor device according to one embodiment of the present invention. [Figure 19] 1 is a cross-sectional view illustrating a semiconductor device according to one embodiment of the present invention. [Figure 20]1 is a cross-sectional view illustrating a semiconductor device according to one embodiment of the present invention. [Figure 21] FIG. 1 is a top view illustrating a semiconductor device according to one embodiment of the present invention. [Figure 22] 1 is a cross-sectional view illustrating a semiconductor device according to one embodiment of the present invention. [Diagram 23] 1A and 1B are a cross-sectional view and a top view illustrating a semiconductor device according to one embodiment of the present invention. [Figure 24] 1A to 1C are diagrams illustrating electronic devices using a semiconductor device which is one embodiment of the present invention. [Diagram 25] 1A to 1C are diagrams illustrating electronic devices using a semiconductor device which is one embodiment of the present invention. [Figure 26] FIG. 2 is a diagram illustrating a sample structure. [Figure 27] FIG. 1 is a diagram illustrating sheet resistance. [Figure 28] FIG. 1 is a diagram for explaining the measurement results of SIMS. [Figure 29] FIG. 1 is a diagram illustrating the measurement results of ESR. [Diagram 30] FIG. 1 is a diagram illustrating the measurement results of ESR. [Diagram 31] FIG. 1 is a diagram illustrating sheet resistance. [Diagram 32] FIG. 1 is a diagram illustrating sheet resistance. [Diagram 33] A diagram explaining a bulk model of an InGaZnO4 crystal. [Diagram 34] Diagram illustrating the formation energy and thermodynamic transition levels of VoH. [Diagram 35] 1A to 1C are diagrams illustrating a manufacturing process of a sample and a sheet resistance of the sample. [Diagram 36] 1A to 1C are diagrams illustrating a manufacturing process of a sample and its structure. [Figure 37] FIG. 1 is a diagram illustrating the transmittance of a sample. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following description, and it is understood by those skilled in the art that various changes can be made in form and detail. The present invention is not limited to the description of the following embodiments. It is not something that is done.

[0032] In the configuration of the present invention described below, the same parts or parts having similar functions are designated by the same reference numerals. The same reference numerals are used in different drawings, and the repeated explanations are omitted. When referring to a part having a function, the hatch pattern is the same and no symbol is attached. be.

[0033] In each figure described in this specification, the size of each structure, the thickness of the film, or the area is not shown for the sake of clarity. The figures may be exaggerated for illustrative purposes and are not necessarily limited to that scale.

[0034] In this specification and elsewhere, ordinal numbers such as 1st, 2nd, etc. are used for convenience. In addition, the order of steps or stacking is not intended to specify the invention in the present specification, etc. The above does not indicate the specific name of the item.

[0035] In addition, the function of the "source" and "drain" in the present invention is to control the flow of current during circuit operation. In cases where the direction is changed, the positions may be reversed. The terms "source" and "drain" may be used interchangeably.

[0036] Voltage is the potential difference between two points, and potential is the electrostatic field at a certain point. This refers to the electrostatic energy (electrical potential energy) possessed by a unit charge in a particle. Generally, the potential difference between a potential at a certain point and a reference potential (for example, ground potential) This is simply called potential or voltage, and potential and voltage are often used synonymously. Therefore, in this specification, unless otherwise specified, potential may be read as voltage. In this specification, voltage may be read as potential.

[0037] In this specification, when etching is performed after photolithography, The mask formed by the photolithography process is removed.

[0038] (Embodiment 1) In this embodiment, a semiconductor device which is one embodiment of the present invention will be described with reference to drawings. Note that in this embodiment, a liquid crystal display device is used as an example of a semiconductor device according to one embodiment of the present invention. explain.

[0039] <Configuration of Semiconductor Device> FIG. 1A shows an example of a semiconductor device. The semiconductor device shown in FIG. 0, the scanning line driving circuit 104, and the signal line driving circuit 106 are arranged in parallel or approximately in parallel. m scanning lines 107 whose potentials are controlled by a scanning line driving circuit 104; are arranged in parallel or approximately in parallel, and the potential is controlled by a signal line driver circuit 106. and a signal line 109. The pixel section 100 further includes a plurality of The pixel 201 is arranged parallel or approximately parallel to the scanning line 107. The capacitance lines 115 are arranged parallel to or parallel to the signal lines 109. They may be disposed approximately in parallel.

[0040] Each scanning line 107 corresponds to one of the pixels 201 arranged in m rows and n columns in the pixel section 100. The signal lines 109 are electrically connected to the n pixels 201 arranged in any one row. is m pixels 201 arranged in m rows and n columns, and m pixels 201 arranged in any one of the columns. 1. m and n are both integers of 1 or more. is n pixels 201 arranged in any one of the rows among the pixels 201 arranged in m rows and n columns. 1. Capacitive lines 115 are arranged parallel to or in parallel with the signal line 109. In the case where the pixels 201 are arranged in m rows and n columns, It is electrically connected to m pixels 201 arranged in a column.

[0041] FIG. 1B is an example of a circuit diagram of a pixel 201 included in the semiconductor device shown in FIG. The pixel 201 shown in FIG. 1B is electrically connected to the scanning line 107 and the signal line 109. A transistor 103, one electrode of which is electrically connected to the drain electrode of the transistor 103. The other electrode of the capacitor element 2 is electrically connected to a capacitor line 115 that supplies a constant potential. 05, a pixel electrode is a drain electrode of the transistor 103 and one electrode of the capacitor 205. An electrode (counter electrode) that is electrically connected to the pixel electrode supplies a counter potential. and a liquid crystal element 108 electrically connected to the wiring.

[0042] The liquid crystal element 108 is formed by a substrate on which the transistor 103 and the pixel electrode are formed and a counter electrode. The optical modulation effect of the liquid crystal sandwiched between the substrates controls the transmission or non-transmission of light. The optical modulation action of the liquid crystal is controlled by the electric field applied to the liquid crystal (vertical electric field or The electric field includes an oblique electric field.) In addition, on the substrate on which the pixel electrode is formed, When an opposing electrode (also called a common electrode) is formed on the liquid crystal, the electric field applied to the liquid crystal is a lateral electric field. It becomes a world.

[0043] Next, a specific example of the pixel 201 of the liquid crystal display device will be described. This is shown in Fig. 2. In Fig. 2, the counter electrode and the liquid crystal element are omitted.

[0044] In FIG. 2, the scanning lines 107 extend in a direction substantially perpendicular to the signal lines 109 (the left-right direction in the figure). The signal lines 109 extend in a direction substantially perpendicular to the scanning lines 107 (the vertical direction in the figure). The capacitance line 115 is provided so as to extend in a direction parallel to the scanning line 107. The scanning line 107 and the capacitance line 115 are connected to the scanning line driving circuit 104 (FIG. 1(A)). ) and the signal line 109 is electrically connected to a signal line driver circuit 106 (see FIG. 1 See (A).)

[0045] The transistor 103 is provided in a region where the scanning line 107 and the signal line 109 intersect. The transistor 103 includes at least a semiconductor film 111 having a channel formation region, A gate electrode, a gate insulating film (not shown in FIG. 2), a source electrode, and a drain electrode In addition, in the scan line 107, a region overlapping with the semiconductor film 111 is a transistor. The gate electrode 103 functions as a gate electrode of the signal line 109. The conductive film 113 is a semiconductor. The region overlapping with the film 111 functions as the drain electrode of the transistor 103. , the gate electrode, the source electrode, and the drain electrode are respectively connected to the scanning line 107 and the signal line 109. 2, the top surface of the scan line 107 is shown as a conductive film 113. Therefore, the end of the scanning line 107 is located outside the end of the semiconductor film. This functions as a light-shielding film that blocks light from light sources such as LEDs. Therefore, the semiconductor film 111 is not irradiated with light, and thus the change in the electrical characteristics of the transistor can be suppressed. Cut.

[0046] In addition, when oxide semiconductors are treated under appropriate conditions, the off-state current of transistors can be reduced significantly. In one embodiment of the present invention, an oxide semiconductor is used for the semiconductor film 111 because the semiconductor film 111 can reduce the This makes it possible to reduce the power consumption of the semiconductor device.

[0047] The conductive film 113 is a pixel electrode formed of a conductive film having a light-transmitting property through the opening 117. In FIG. 2, the pixel electrode 221 is shown as a hatched portion. is omitted in the figure.

[0048] The capacitance element 205 is provided in a region surrounded by the capacitance line 115 and the signal line 109 in the pixel 201. The capacitor element 205 is connected to a capacitor line through a conductive film 125 provided in the opening 123. The capacitor 205 is electrically connected to a light-transmitting conductive film 119 and A pixel electrode 221 having light transmitting properties and a dielectric film formed on the transistor 103 The capacitor element 205 is made of a light-transmitting insulating film (not shown in FIG. 2). has light-transmitting properties.

[0049] Since the capacitor 205 has a light-transmitting property, the capacitor 205 is large in the pixel 201. Therefore, the aperture ratio can be increased, typically by 55%. It is possible to increase the charge capacity to 60% or more, preferably 60% or more. For example, a semiconductor device with high resolution, such as a liquid crystal display device, can be obtained. In this case, the area of ​​the pixel is small, and the area of ​​the capacitance element is also small. In a semiconductor device with a low capacitance, the charge capacity stored in the capacitance element is small. Since the capacitor 205 shown in the embodiment has a light-transmitting property, the capacitor can be provided in a pixel. As a result, it is possible to increase the aperture ratio while obtaining a sufficient charge capacity in each pixel. The pixel density is 200ppi or more, and even 300ppi or more. In addition, one embodiment of the present invention can be suitably used in a high-resolution display device. Since the aperture ratio can be increased, light from light sources such as backlights can be used efficiently. This makes it possible to reduce the power consumption of the display device.

[0050] Here, the characteristics of a transistor using an oxide semiconductor will be described. The transistor used is an n-channel transistor. Oxygen vacancies can generate carriers, which can affect the electrical characteristics and reliability of transistors. For example, shifting the threshold voltage of a transistor in the negative direction However, when the gate voltage is 0V, drain current may flow. A transistor in which drain current flows when the input voltage is 0V is called a normally-on transistor. A transistor having such characteristics is called a depletion type transistor. In addition, when the gate voltage is 0V, it can be considered that no drain current flows. A transistor that has such characteristics is called an enhanced transistor. This is called a modulation transistor.

[0051] When an oxide semiconductor is used for the semiconductor film 111, It is preferable that the defects, typically oxygen vacancies, contained in the alloy are reduced as much as possible. For example, The electron spin resonance method, in which a magnetic field was applied parallel to the film surface, gave a g value of 1.93. The defect density (corresponding to the defect density in the oxide semiconductor film) was below the lower limit of detection by the measurement device. Defects contained in the oxide semiconductor film, typically oxygen vacancies, are preferably reduced. By reducing the above as much as possible, the transistor 103 is prevented from becoming a normally-on transistor. This can suppress the electric field and improve the electrical characteristics and reliability of the semiconductor device. The power consumption of the semiconductor device can be reduced.

[0052] The negative shift in the threshold voltage of a transistor is not only due to oxygen vacancies, but also due to oxide It can also be caused by hydrogen contained in semiconductors (including hydrogen compounds such as water). Hydrogen contained in oxide semiconductors reacts with oxygen that is bonded to metal atoms to form water. A defect (which can also be called an oxygen defect) is formed in the lattice from which oxygen has been removed (or in the part from which oxygen has been removed). In addition, some of the hydrogen reacts with oxygen to generate electrons, which act as carriers. Therefore, a transistor using an oxide semiconductor containing hydrogen has a normally-on characteristic. It is easy to become sexually

[0053] Therefore, when an oxide semiconductor is used for the semiconductor film 111, It is preferable that the semiconductor film has as little hydrogen as possible. In this study, secondary ion mass spectrometry (SIMS) was used. The hydrogen concentration obtained by spectrometer is 5×10 18 atoms / cm 3 Less than 1 x 10 18 atoms / cm 3 Less than or equal to 5×10 17 a toms / cm 3 Less than 1×10, more preferably 16 atoms / cm 3 The following applies.

[0054] The semiconductor film 111 is also made of an alkali metal or aluminum oxide obtained by secondary ion mass spectrometry. The concentration of potassium earth metals is 1×10 18 atoms / cm 3 Less than or equal to 2 x 10 16 atoms / cm 3 Alkali metals and alkaline earth metals are oxide semiconductors. The combination may generate carriers, which increases the off-state current of the transistor 103. There are times when this happens.

[0055] In addition, when nitrogen is contained in the oxide semiconductor film that is the semiconductor film 111, the carrier Electrons are generated, the carrier density increases, and it becomes easier to make the material n-type. Transistors using oxide semiconductors tend to be normally-on. In the semiconductor film, it is preferable that the nitrogen is reduced as much as possible. For example, Degrees are 5 x 10 18 atoms / cm 3 It is preferable to do the following:

[0056] In this way, impurities (hydrogen, nitrogen, alkali metals or alkaline earth metals, etc.) can be removed. The oxide semiconductor film 111 is purified by reducing the amount of oxygen as much as possible, and the semiconductor film 111 is thus formed. Therefore, the transistor 103 can be prevented from becoming a normally-on transistor. The off-current of the transistor 103 can be significantly reduced. This leads to excellent electrical characteristics. In addition, a semiconductor device having improved reliability can be manufactured. can.

[0057] The reason why the off-state current of a transistor using a highly purified oxide semiconductor film is low is that This can be proved by various experiments. For example, when the channel width is 1×10 6 Channel length L in μm Even if the element has a thickness of 10 μm, the voltage between the source and drain electrodes (drain voltage) is 1 In the range from V to 10 V, the off-state current is below the measurement limit of the semiconductor parameter analyzer. , i.e. 1 × 10 -13 In this case, the transistor The off-state current, which is equivalent to the value divided by the channel width of the transistor, must be 100zA / μm or less. In addition, a capacitor and a transistor are connected to each other, and current flows into the capacitor or flows out of the capacitor. The off-state current is measured using a circuit that controls the outflow of charge by the transistor. In the measurement, a highly purified oxide semiconductor film was used for the channel formation region of the transistor. The off-state current of the transistor is measured based on the change in the amount of charge per unit time of the capacitor. As a result, when the voltage between the source and drain electrodes of the transistor is 3V, several tens of Therefore, a low off-state current of 1.0 A / μm can be obtained. A transistor using the film has an extremely small off-state current.

[0058] Next, cross-sectional views of the dashed lines A1-A2 and B1-B2 in FIG. As shown in.

[0059] The cross-sectional structure of a pixel 201 of the liquid crystal display device is as follows. An element portion formed on the substrate 150 and an element portion formed on the substrate 150 are sandwiched between the two element portions. and a liquid crystal layer.

[0060] First, the structure of the element portion provided on the substrate 102 will be described. , a scanning line 107 including a gate electrode 107a of the transistor 103, and a scanning line 107 having the same The scanning line 107 and the capacitance line 115 are provided on the surface. A gate insulating film 127 is provided on the gate insulating film 127. The gate insulating film 127 overlaps with the scanning line 107. A semiconductor film 111 is provided on the region where the semiconductor film 111 is to be formed, and a light-transmitting A conductive film 119 is provided on the semiconductor film 111 and the gate insulating film 127. A signal line 109 including a source electrode 109a of the transistor 103 and a drain electrode 109b of the transistor 103 A conductive film 113 including an electrode 113a is provided. The gate insulating film 127 is provided with a capacitance line 1 An opening 123 is provided that reaches the gate insulating film 127 and the transparent electrode 124. A conductive film 125 is provided over the conductive film 119 having optical properties. A transistor 1 is disposed on the signal line 109, the semiconductor film 111, the conductive film 113, and the conductive film 125. 03, an insulating film 229, an insulating film 231, and an insulating film 232 which function as protective insulating films are provided. In addition, at least in a region that becomes the capacitor 205, An insulating film 232 is provided in contact with the film 119. The insulating film 232 is provided with an opening 117 that reaches the conductive film 113. The pixel electrode 221 is provided on the insulating film 232. An insulating film 158 that functions as an alignment film is provided on the substrate 102. A base insulating film is provided between the gate insulating film 127 and the capacitance line 115. This is also fine.

[0061] In the capacitor 205 shown in this embodiment, one of a pair of electrodes is a pixel electrode 221. The other electrode of the pair of electrodes is a semiconductor film formed in the same process as the semiconductor film 111. The conductive film 119 has a light-transmitting property and is made of a metal oxide film having a conductive property. By using the dielectric film provided between the insulating film 232, the thickness of the dielectric film can be reduced. Therefore, the charge capacity of the capacitor 205 can be increased.

[0062] Moreover, the insulating film 232 is preferably a nitride insulating film.

[0063] In FIG. 2, an insulating film 229 (not shown) and an insulating film 231 (not shown) The end of the region where no conductive film is provided (inside the two-dot dashed line) is located outside the conductive film 119 having light transmitting properties. 4, an insulating film 279 (not shown) and an insulating film 281 (not shown) are provided. The end of the region (inside the two-dot dashed line) where the conductive film 11 is not provided is covered with the conductive film 11 having light transmitting properties. 9.

[0064] FIG. 5 shows cross-sectional views taken along dashed dotted lines A1-A2 and B1-B2 in FIG.

[0065] In FIG. 5, the gate insulating film 127, the signal line 109, the semiconductor film 111, the conductive film The protection layer 113, the conductive film 125, and the light-transmitting conductive film 119 are provided on the transistor 103. An insulating film 279, an insulating film 281, and an insulating film 282 which function as insulating films are provided. In addition, end portions of the insulating film 279 and the insulating film 281 are positioned over the light-transmitting conductive film 119. In addition, an insulating film 282 is provided over the light-transmitting conductive film 119. The capacitor 255 is composed of a conductive film 119 having a light-transmitting property, an insulating film 282, and a pixel electrode 271. The insulating film 279, the insulating film 281, and the insulating film 282 are formed. The insulating film 29 can be formed using a material similar to that of the insulating film 231 and the insulating film 232. In addition, the pixel electrode 271 can be formed using the same material as the pixel electrode 221. 5, the end portions of the insulating film 279 and the insulating film 281 are formed on the conductive film 119 having light-transmitting properties. Therefore, the gate insulating film 12 is not etched when the insulating film 279 and the insulating film 281 are etched. 7. Excessive etching of the film 7 can be prevented.

[0066] The components of the above structure are described in detail below.

[0067] There is no particular restriction on the material of the substrate 102, but at least in the manufacturing process of the semiconductor device, For example, a glass substrate, There are ceramic substrates, plastic substrates, etc., and glass substrates are barium borosilicate Non-alkali glass such as acid glass, aluminoborosilicate glass or aluminosilicate glass Alternatively, a substrate that does not have light transmission properties, such as a stainless steel alloy, may be used. In this case, it is preferable to provide an insulating film on the surface of the substrate. 2. Quartz substrate, sapphire substrate, single crystal semiconductor substrate, polycrystalline semiconductor substrate, compound semiconductor substrate It is also possible to use a solid substrate, SOI (Silicon On Insulator) substrate, etc. can.

[0068] Since the scanning line 107 and the capacitance line 115 pass a large current, they are preferably formed of a metal film. Typically, molybdenum (Mo), titanium (Ti), tungsten (W), tantalum (T a), aluminum (Al), copper (Cu), chromium (Cr), neodymium (Nd), scandium (Sn) A single-layer structure or a multi-layer structure using metal materials such as Sc (Sc) or alloy materials mainly composed of these. is provided in a laminated structure.

[0069] As an example of the scanning line 107 and the capacitance line 115, aluminum containing silicon is used. Single layer structure, double layer structure with titanium laminated on aluminum, titanium laminated on titanium nitride Two-layer structure with tungsten on titanium nitride, two-layer structure with tungsten on tantalum nitride Two-layer structure with stainless steel laminated, two-layer structure with copper laminated on copper-magnesium-aluminum alloy Structure: Three-layer structure in which copper is layered on titanium nitride and tungsten is formed on top of that There is.

[0070] In addition, the scanning line 107 and the capacitance line 115 may be made of a light-transmitting material that is applicable to the pixel electrode 221. A conductive material having such a property can be used.

[0071] Furthermore, as the material of the scanning line 107 and the capacitance line 115, a metal oxide containing nitrogen, specifically The following oxides are considered: In-Ga-Zn oxides containing nitrogen, In-Sn oxides containing nitrogen, and In-Ga oxides containing nitrogen, In-Zn oxides containing nitrogen, and Sn oxides containing nitrogen Materials that can be used include In-based oxides that contain nitrogen, and metal nitride films (InN, SnN, etc.). These materials have a work function of 5 eV (electron volts) or more. When an oxide semiconductor is used for the semiconductor film 111 of the third transistor, By using a metal oxide containing nitrogen as a gate electrode, the threshold voltage of the transistor 103 is The transistor has a normally-off characteristic, and the voltage can be changed in the positive direction. For example, when using an In-Ga-Zn oxide containing nitrogen, at least In both cases, the nitrogen concentration is higher than that of the oxide semiconductor film of the semiconductor film 111, specifically, the nitrogen concentration is 7 atomic %. The above-mentioned In-Ga-Zn oxides can be used.

[0072] The scanning lines 107 and the capacitance lines 115 are made of low resistance materials such as aluminum and copper. It is preferable to use aluminum or copper to reduce signal delay and improve display quality. Aluminum has low heat resistance and can form hillocks, whiskers, or Defects due to migration are likely to occur. To prevent aluminum migration, Therefore, aluminum is more susceptible to the presence of other metals that melt faster than aluminum, such as molybdenum, titanium, and tungsten. It is preferable to use a metal material with a high migration resistance. In order to prevent defects caused by tin and the diffusion of copper elements, copper-containing materials such as molybdenum, titanium, and tungsten are used. It is preferable to laminate a metal material having a higher melting point than the above.

[0073] The gate insulating film 127 is made of, for example, silicon oxide, silicon oxynitride, silicon nitride oxide, Silicon nitride, aluminum oxide, hafnium oxide, gallium oxide or Ga-Zn metal The semiconductor film 111 is provided to have a single layer structure or a multilayer structure using an insulating material such as an oxide. In order to improve the interface characteristics with the oxide semiconductor film, which is a gate insulating film 127, At least a region in contact with the semiconductor film 111 is preferably formed using an oxide insulating film.

[0074] In addition, the gate insulating film 127 is formed of an insulating film having a barrier property against oxygen, hydrogen, water, etc. By providing the insulating layer, oxygen can be diffused from the oxide semiconductor film, which is the semiconductor film 111, to the outside and Therefore, it is possible to prevent hydrogen, water, and the like from entering the oxide semiconductor film. As insulating films having a barrier property against such substances, aluminum oxide and aluminum oxynitride are used. , gallium oxide, gallium oxynitride, yttrium oxide, yttrium oxynitride, halide Examples include hafnium, hafnium oxynitride, and silicon nitride.

[0075] The gate insulating film 127 is made of hafnium silicate (HfSiO x ), nitrogen-containing Hafnium silicate (HfSi x O y N z ), hafnium aluminate with nitrogen HfAl x O y N z ), high-k materials such as hafnium oxide and yttrium oxide By using this, the gate leakage of the transistor 103 can be reduced.

[0076] The gate insulating film 127 preferably has the following laminated structure: A silicon nitride film with few defects is provided as a contact film, and a second silicon nitride film is formed on the first silicon nitride film. As the silicon nitride film, a silicon nitride film with a small amount of hydrogen desorption and ammonia desorption is provided. On the second silicon nitride film, any one of the oxide insulating films listed in the gate insulating film 127 is formed. It is preferable to provide:

[0077] The second silicon nitride film is a film that has a hydrogen molecule desorption rate of 5.0 or more in thermal desorption gas spectrometry. ×10 21 molecules / cm 3 Less than 3 x 10 21 molecules / cm 3 The following is more preferable: 1×10 21 molecules / cm 3 The number of ammonia molecules released is less than 1×10 22 molecule / cm 3 Less than 5 x 10 21 molecules / cm 3 Less than 1×10, more preferably 2 1 molecule / cm 3 It is preferable to use a nitride insulating film having the following properties: The gate insulating film 127 is formed by using the first silicon nitride film and the second silicon nitride film as a part of the gate insulating film 127. The insulating film 127 is a gate insulating film having a small amount of defects and a small amount of hydrogen and ammonia desorbed. As a result, the hydrogen and nitrogen contained in the gate insulating film 127 can be prevented from being depleted. Therefore, the amount of transfer to the semiconductor film 111 can be reduced.

[0078] In a transistor using an oxide semiconductor, If a trap state (also called an interface state) exists in the gate insulating film, the threshold of the transistor The negative shift of the threshold voltage, typically the negative shift of the threshold voltage, and the The subthreshold voltage required to change the drain current by one order of magnitude when the device is turned on. This causes an increase in the shock coefficient (S value). As a result, the electrical characteristics of each transistor For this reason, silicon nitride with fewer defects is used as the gate insulating film. By using an oxide insulating film and providing an oxide insulating film in a region in contact with the semiconductor film 111, The negative shift of the threshold voltage can be reduced, and the increase in the S value can be suppressed.

[0079] The thickness of the gate insulating film 127 is preferably 5 nm or more and 400 nm or less, more preferably 10 nm or less. The thickness is preferably at most 300 nm, and more preferably at least 50 nm and at most 250 nm.

[0080] The semiconductor film 111 is an oxide semiconductor film. The oxide semiconductor film has an amorphous structure or a single crystal structure. The semiconductor film 111 may have a thickness of 1 nm or more. 100 nm or less, preferably 1 nm to 50 nm, more preferably 1 nm to 30 nm m or less, and more preferably 3 nm or more and 20 nm or less.

[0081] As an oxide semiconductor applicable to the semiconductor film 111, an energy gap of 2 eV or more, The energy is preferably 2.5 eV or more, and more preferably 3 eV or more. The off-state current of the transistor 103 is reduced by using an oxide semiconductor with a wide gap. It is possible.

[0082] The oxide semiconductor applicable to the semiconductor film 111 is at least indium (In) or It is preferable that the alloy contains zinc (Zn). Or, it is preferable that the alloy contains both In and Zn. In addition, in order to reduce variation in electrical characteristics of transistors using the oxide semiconductor, In addition, it is preferable to have one or more stabilizers.

[0083] The stabilizers are gallium (Ga), tin (Sn), hafnium (Hf), and aluminium. Aluminum (Al) or zirconium (Zr). Also, with other stabilizers The lanthanides lanthanum (La), cerium (Ce), and praseodymium (P r), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium ( Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium Er, Thulium, Tm, Ytterbium, Lutetium, etc. do.

[0084] Examples of oxide semiconductors that can be used for the semiconductor film 111 include oxide semiconductors such as Indium oxide, tin oxide, zinc oxide, In-Zn oxide, which is an oxide containing two kinds of metals substances, Sn-Zn oxides, Al-Zn oxides, Zn-Mg oxides, Sn-Mg oxides In-Mg oxide, In-Ga oxide, and In- Ga-Zn oxide (also written as IGZO), In-Al-Zn oxide, In-Sn -Zn oxide, Sn-Ga-Zn oxide, Al-Ga-Zn oxide, Sn-Al- Zn-based oxide, In-Hf-Zn-based oxide, In-Zr-Zn-based oxide, In-Ti-Z n-based oxide, In-Sc-Zn-based oxide, In-Y-Zn-based oxide, In-La-Zn-based Oxide, In-Ce-Zn oxide, In-Pr-Zn oxide, In-Nd-Zn oxide oxides, In-Sm-Zn oxides, In-Eu-Zn oxides, In-Gd-Zn oxides In-Tb-Zn oxide, In-Dy-Zn oxide, In-Ho-Zn oxide , In-Er-Zn oxide, In-Tm-Zn oxide, In-Yb-Zn oxide, In-Lu-Zn ​​oxide, In-Sn-Ga-Zn oxide containing four metals Oxide, In-Hf-Ga-Zn oxide, In-Al-Ga-Zn oxide, In-S n-Al-Zn oxide, In-Sn-Hf-Zn oxide, In-Hf-Al-Zn An oxide can be used.

[0085] Here, the In-Ga-Zn oxide is an oxide having In, Ga, and Zn as the main components. The ratio of In, Ga, and Zn does not matter. The metal elements may be included.

[0086] In addition, InMO 3 (ZnO) m Using materials expressed as (m>0) M may be one or more metal elements selected from Ga, Fe, Mn, and Co. or the above-mentioned elements as a stabilizer.

[0087] For example, In:Ga:Zn=1:1:1 (=1 / 3:1 / 3:1 / 3), In:Ga: Zn=2:2:1 (=2 / 5:2 / 5:1 / 5), or In:Ga:Zn=3:1: The In-Ga-Zn metal oxide with an atomic ratio of 2 (=1 / 2:1 / 6:1 / 3) is used. Alternatively, In:Sn:Zn=1:1:1 (=1 / 3:1 / 3:1 / 3), In:Sn:Zn=2:1:3(=1 / 3:1 / 6:1 / 2) or In:Sn:Zn In-Sn-Zn metal oxide with an atomic ratio of =2:1:5 (=1 / 4:1 / 8:5 / 8) The atomic ratio of metal elements contained in the metal oxide should be calculated by subtracting the above from the atomic ratio. The atomic ratio may vary by ±20%.

[0088] However, the present invention is not limited to these, and the semiconductor properties and electrical properties required (field effect mobility, etc.) The appropriate atomic ratio can be used according to the required semiconductor. In order to obtain the desired characteristics, the carrier density, impurity concentration, defect density, atomic ratio of metal elements to oxygen, It is preferable to make the interatomic distance, density, etc. appropriate. For example, In-Sn-Zn based oxide It is relatively easy to obtain high field effect mobility in In-Ga-Zn In the case of oxides containing GaN, the field effect mobility can be increased by reducing the defect density in the bulk. can.

[0089] The light-transmitting conductive film 119 is mainly made of the same material as the semiconductor film 111 and contains nitrogen. By containing hydrogen and / or hydrogen, the electrical conductivity is increased and the material has conductor properties. It is formed from metal oxides.

[0090] The semiconductor film 111 and the light-transmitting conductive film 119 are both formed over a gate insulating film. The metal oxide films are made of the same metal elements, but have different impurity concentrations. In other words, the impurity concentration of the light-transmitting conductive film 119 is higher than that of the semiconductor film 111. For example, the hydrogen concentration in the semiconductor film 111 is 5×10 19 atoms / cm 3 Less than, good Preferably 5 x 10 18 atoms / cm 3 less than 1×10 18 atoms / cm 3 Less than or equal to 5×10 17 atoms / cm 3 More preferably, 1×10 16 atoms / cm 3 The water contained in the light-transmitting conductive film 119 is The elementary concentration is 8×10 19 atoms / cm 3More than 1×10 20 atoms / cm 3 More preferably, 5×10 20 atoms / cm 3 That's all. In addition, The hydrogen concentration in the light-transmitting conductive film 119 is preferably twice as high as that in the light-transmitting conductive film 111. is more than 10 times higher.

[0091] In addition, the light-transmitting conductive film 119 has a lower resistivity than the semiconductor film 111. The resistivity of the conductive film 119 is 1×10 -8 More than 1×10 -1 times or less, typically 1×10 -3 Ωcm or more 1×10 4 Less than Ωcm , and more preferably, the resistivity is 1×10 -3 Ωcm or more 1×10 -1 Less than Ωcm good.

[0092] A signal line 109 including a source electrode 109a of the transistor 103, The conductive film 113 including the drain electrode and the light-transmitting conductive film 119 of the capacitor 205 The conductive film 125 electrically connected to the capacitance line 115 is formed by applying a suitable amount to the scanning line 107 and the capacitance line 115. The insulating layer 10 may have a single layer structure or a laminate structure using a material that can be used.

[0093] An insulating film that functions as a protective insulating film of the transistor 103 and a dielectric film of the capacitor 205 The film 229, the insulating film 231, and the insulating film 232 are made of a material that can be used for the gate insulating film 127. In particular, the insulating films 229 and 231 are oxide insulating films. It is preferable that the insulating film 232 is a nitride insulating film. Impurities such as hydrogen and water from the outside enter the transistor 103 (particularly the semiconductor film 111). Note that the insulating film 229 does not necessarily have to be provided.

[0094] In addition, one or both of the insulating films 229 and 231 may contain oxygen having a stoichiometric composition. It is preferable that the oxide insulating film contains more oxygen than the oxide insulating film. In order to prevent oxygen from being released from the oxide semiconductor film and to prevent oxygen from being contained in the oxide insulating film containing excess oxygen, The oxygen contained in the oxide semiconductor film can be moved to the oxide semiconductor film, thereby reducing oxygen vacancies. For example, the release of oxygen molecules measured by thermal desorption spectrometry (hereinafter referred to as TDS analysis) Output is 1.0 x 10 18 molecule / cm 3 By using the oxide insulating film having the above structure, The oxygen vacancies in the semiconductor film can be reduced. In one or both of 31, oxygen is contained in excess of the stoichiometric composition (oxygen excess region) The insulating film may be an oxide insulating film that partially overlaps with the semiconductor film 111. When an oxygen excess region is present in the region where the oxide semiconductor film is formed, oxygen is prevented from being released from the oxide semiconductor film. At the same time, oxygen contained in the excess oxygen is moved to the oxide semiconductor film, thereby reducing oxygen vacancies. It becomes possible to do so.

[0095] The insulating film 231 is an oxide insulating film containing more oxygen than the oxygen that satisfies the stoichiometric composition. In this case, the insulating film 229 is preferably an oxide insulating film that transmits oxygen. In the insulating film 229, all oxygen that enters the insulating film 229 from the outside passes through the insulating film 229 and migrates. Some oxygen does not move and remains in the insulating film 229. Some oxygen migrates from the insulating film 229 to the outside. It is preferable that the insulating oxide film has a large coefficient.

[0096] In addition, the insulating film 229 is in contact with the oxide semiconductor film, which is the semiconductor film 111; therefore, The oxide insulating film must not only be transparent, but also have a low interface state with the semiconductor film 111. For example, the insulating film 229 is preferably an oxide insulating film having a lower defect density than the insulating film 231. Specifically, the g value measured by electron spin resonance is 2.001 (E ´-center) spin density is 3.0×10 17 spins / cm 3 The following is preferably is 5.0 x 10 16 spins / cm 3 The oxide insulating film is shown below. The measured spin density of g-value=2.001 is the dangling bond in the insulating film 229. corresponds to the abundance of

[0097] The thickness of the insulating film 229 is 5 nm or more and 150 nm or less, preferably 5 nm or more and 50 nm or less. The thickness of the insulating film 231 can be set to 10 nm or less and preferably 30 nm or less. The thickness can be set to 30 nm or more and 500 nm or less, preferably 150 nm or more and 400 nm or less. Cut.

[0098] When the insulating film 232 is a nitride insulating film, one or both of the insulating film 229 and the insulating film 231 It is preferable that the insulating film has a barrier property against nitrogen. For example, a dense oxide insulating film is preferable. By forming a film, it is possible to provide a barrier against nitrogen. Specifically, at 25° C. Oxide insulating film with an etching rate of 10 nm / min or less when using 0.5% by weight hydrofluoric acid. A membrane is preferred.

[0099] Note that one or both of the insulating films 229 and 231 may be formed using silicon oxynitride or silicon oxynitride. When using an oxide insulating film containing nitrogen, such as silicon oxide, the nitrogen concentration obtained by SIMS is SIMS detection limit above 3×10 20 atoms / cm 3 Less than 1 x 10 18 a toms / cm 3 More than 1×10 20 atoms / cm 3 It is preferable to set the following: By doing so, the amount of nitrogen transferred to the semiconductor film 111 included in the transistor 103 is reduced. In addition, by doing so, defects in the oxide insulating film itself containing nitrogen can be eliminated. The amount can be reduced.

[0100] As the insulating film 232, a nitride insulating film with a low hydrogen content may be provided. For example, the amount of hydrogen molecules released as measured by TDS analysis is 5.0 × 10 2 1 / cm 3 less than 3.0×10 21 / cm 3 less than 100%, and more preferably 1.0×10 21 / cm 3 It is a nitride insulating film having a thickness of less than 100 nm.

[0101] The insulating film 232 has a thickness capable of suppressing the intrusion of impurities such as hydrogen and water from the outside. For example, the thickness is 50 nm or more and 200 nm or less, preferably 50 nm or more and 150 nm or less. The thickness can be set to 50 nm or less and more preferably 100 nm or less.

[0102] In addition, an organic silane gas is injected between the insulating film 231 and the insulating film 232 or on the insulating film 232. Alternatively, a silicon oxide film formed by a CVD method using a step-type silicon oxide film may be provided. Since it has excellent differential coverage, it is useful as a protective insulating film for the transistor 103. The silicon oxide film can be formed to a thickness of 300 nm to 600 nm. Organic silane gas As an example, ethyl silicate (TEOS: chemical formula Si(OC 2 H 5 ) 4 ), tetramethylsilane (TMS: Chemical formula Si(CH 3 ) 4 ), Tetramethylcyclotetrasiloxane (TMCT) S), Octamethylcyclotetrasiloxane (OMCTS), Hexamethyldisilazane ( HMDS, triethoxysilane (SiH(OC 2 H 5 ) 3 ), Tris(dimethylamino)silane Ran(SiH(N(CH 3 ) 2 ) 3 Silicon-containing compounds such as

[0103] The silicon oxide film is provided between the insulating film 231 and the insulating film 232 or on the insulating film 232. By this, the flatness of the surface of the element portion where the transistor and the capacitor are provided can be improved. In addition, the silicon oxide film is provided between the insulating film 231 and the insulating film 232 to provide insulation. By using the nitride insulating film as the film 232, impurities such as hydrogen and water from the outside can be prevented from impurifying the semiconductor film 1. This can further prevent the conductive film 11 and the light-transmitting conductive film 119 from entering the conductive film 11 and the light-transmitting conductive film 119 .

[0104] In addition, when a silicon oxide film is provided on the insulating film 232, the insulating film 232 and the silicon oxide film The insulating film 232 functions as a dielectric film of the capacitance element 205. However, compared with oxide insulating films such as silicon oxide, nitride insulating films have a higher relative dielectric constant and are less susceptible to internal stress. Therefore, a silicon oxide film is used as the dielectric film of the capacitance element 205. When only the insulating film 232 is used without using the insulating film 232, if the insulating film 232 is thin, the capacitance element 205 The capacitance value of the capacitor becomes too large, and the speed at which image signals are written to the pixels is reduced to reduce power consumption. Conversely, if the thickness of the insulating film 232 is large, the internal stress becomes large. This leads to deterioration of electrical characteristics, such as a change in the threshold voltage of the transistor. However, if the internal stress of the insulating film 232 becomes too large, the insulating film 232 may peel off from the substrate 102. However, the insulating film 232 is made of silicon oxide having a lower relative dielectric constant. The insulating film 232 is used as a dielectric film for the capacitance element of the pixel together with the insulating film 232. The dielectric constant of the dielectric film can be adjusted to a desired value without increasing the film thickness of 32. .

[0105] The pixel electrode 221 is formed using a light-transmitting conductive film. Indium oxide, including indium tin oxide, tungsten oxide Indium zinc oxide containing titanium oxide, indium oxide containing titanium oxide Indium tin oxide, indium zinc oxide, indium tin oxide with silicon oxide added, etc. The light-transmitting conductive material is used.

[0106] Next, the structure of the element portion provided on the substrate 150 will be described. A light-shielding film 152 and an electrode (opposite electrode) provided opposite the pixel electrode 221 and in contact with the light-shielding film 152 In addition, a film that functions as an alignment film in contact with the counter electrode 154 is provided. An insulating film 156 is provided.

[0107] The light-shielding film 152 is formed to prevent light from a light source such as a backlight or from the outside from irradiating the transistor 103. The light-shielding film 152 is made of a material such as metal or organic resin containing a pigment. The light-shielding film 152 can be formed on the transistor 103 of the pixel 201. , a scanning line driver circuit 104, a signal line driver circuit 106 (see FIG. 1), and the like. It may be provided in the region of

[0108] In addition, a colored film having a function of transmitting light of a predetermined wavelength is provided between adjacent light-shielding films 152. Furthermore, an overcoat may be provided between the light-shielding film 152 and the colored film and the counter electrode 154. A coating film may be provided.

[0109] The counter electrode 154 is provided by appropriately using the conductive material having the light transmitting property shown in the pixel electrode 221. do.

[0110] The liquid crystal element 108 includes a pixel electrode 221, a counter electrode 154, and a liquid crystal layer 160. , an insulating film 158 that functions as an alignment film provided in the element portion of the substrate 102, and a substrate 150 The liquid crystal layer 160 is sandwiched between the insulating film 156 that functions as an alignment film provided in the element portion. The pixel electrode 221 and the counter electrode 154 overlap with each other via a liquid crystal layer 160.

[0111] The insulating film 156 and the insulating film 158 functioning as the alignment film are made of a general-purpose material such as polyamide. The material may be used.

[0112] In addition, the insulating film 229 provided on the semiconductor film 111 is made to be permeable to oxygen and to be a semiconductor The insulating film 231 is an oxide insulating film having a low interface state with the substrate film 111, and the insulating film 231 is an oxide insulating film having an oxygen excess region. or an oxide insulating film containing more oxygen than the stoichiometric composition. This makes it easier to supply oxygen to the oxide semiconductor film, which is the semiconductor film 111. In order to prevent oxygen from being released from the oxide semiconductor film, the oxygen contained in the insulating film 231 is It is possible to reduce oxygen vacancies in the oxide semiconductor film by transferring oxygen to the oxide semiconductor film. As a result, the transistor 103 becomes an enhancement type and has a normally-on characteristic. This can improve the electrical characteristics and reliability of the semiconductor device. Furthermore, the power consumption of the semiconductor device can be reduced.

[0113] In addition, by using a nitride insulating film as the insulating film 232 provided over the insulating film 231, Impurities such as hydrogen and water from the outside penetrate the semiconductor film 111 and the light-transmitting conductive film 119. Furthermore, the insulating film 232 can be made of a nitride insulating film having a low hydrogen content. By providing the film, fluctuations in electrical characteristics of the transistor can be suppressed.

[0114] In addition, the capacitance element 205 can be formed large (with a large area) within the pixel 201. As a result, a semiconductor device having an increased aperture ratio and an increased charge capacity can be obtained. As a result, a semiconductor device with excellent display quality can be obtained.

[0115] In addition, since both of the pair of electrodes of the capacitor 205 are conductive, Even if the area is reduced, a sufficient charge capacity can be obtained. Since the ratio is 80 to 90%, the area of ​​the conductive film 119 having light-transmitting properties is reduced, and the pixel 201 By providing a region where the light-transmitting conductive film 119 is not formed in the backlight In other words, the transmittance of light emitted from a light source such as a backlight can be increased. The brightness of the light source can be reduced, and the power consumption of the semiconductor device can be reduced. .

[0116] <Method for manufacturing semiconductor device> Next, a method for manufacturing an element portion provided on the substrate 102 shown in the above semiconductor device will be described. This will be explained with reference to Figs. 6, 7 and 8.

[0117] First, the scanning lines 107 and the capacitance lines 115 are formed on the substrate 102. An insulating film 126, which will be processed into a gate insulating film 127 later, is formed so as to cover the insulating film 115. A semiconductor film 111 is formed in the area overlapping the scanning line 107 of 126, and a pixel electrode 221 is formed later. A semiconductor film 118 is formed so as to overlap with the region where the semiconductor film 118 is to be formed (see FIG. 6A).

[0118] The scanning line 107 and the capacitance line 115 are formed of a conductive film using the above-listed materials. The conductive film can be formed by forming a mask on the conductive film and processing the conductive film using the mask. The film is formed using various deposition methods such as vapor deposition, CVD, sputtering, and spin coating. The thickness of the conductive film is not particularly limited, and the formation time and the desired resistance can be selected. The mask can be determined by taking into consideration the rate of light emission, etc. The conductive film can be processed by a resist mask formed by a process. This can be done by dry etching and / or wet etching.

[0119] The insulating film 126 is formed by a CVD method or a sputtering method using a material that can be used for the gate insulating film 127. The insulating film can be formed by using various film formation methods such as a deposition method.

[0120] In addition, when gallium oxide is used for the gate insulating film 127, MOCVD (Metal Using the Organic Chemical Vapor Deposition method An insulating film 126 can be formed.

[0121] The semiconductor film 111 and the semiconductor film 118 are formed using any of the oxide semiconductors listed above. a mask is formed on the oxide semiconductor film, and the oxide semiconductor film is processed using the mask. Therefore, the semiconductor film 111 and the semiconductor film 118 can be formed of the same metal element. The oxide semiconductor film is formed by sputtering, coating, pulsed laser deposition, laser deposition, etc. The element can be formed by using a printing method. The separated semiconductor film 111 and the semiconductor film 118 can be formed directly on the insulating film 126. When the oxide semiconductor film is formed by a sputtering method, plasma is generated. The power supply for this purpose may be an RF power supply, an AC power supply, or a DC power supply, etc. The sputtering gas is a rare gas (typically argon), oxygen, or a rare gas and oxygen. In the case of a mixed gas of rare gas and oxygen, the ratio of oxygen to rare gas is appropriately set. In addition, it is preferable to increase the gas ratio of the target having a composition of the oxide semiconductor film to be formed. The mask may be selected appropriately according to the second photolithography. The oxide semiconductor film may be formed as a resist mask by a deposition process. The processing can be performed by either or both of dry etching and wet etching. The etching conditions (etching conditions) can be adjusted according to the material so that the desired shape can be etched. The etching conditions (gas, etching solution, etching time, temperature, etc.) are set appropriately.

[0122] After the semiconductor film 111 and the semiconductor film 118 are formed, heat treatment is performed. The oxide semiconductor film that is the semiconductor film 118 is preferably dehydrogenated or dehydrated. The temperature of the heat treatment is typically 150° C. or higher and lower than the substrate distortion point, preferably 200° C. or higher. The temperature is set to 450° C. or lower, and more preferably 300° C. or higher and 450° C. or lower. This may be performed on an oxide semiconductor film before it is processed into the semiconductor film 111 and the semiconductor film 118.

[0123] In this heat treatment, the heat treatment device is not limited to an electric furnace, and a medium such as heated gas may be used. The heat source may be a device that heats the workpiece by thermal conduction or thermal radiation from the workpiece. For example, GRTA (Gas Rapid Thermal Anneal) equipment, LRTA (La Rapid Thermal Anneal (RTA) equipment The LRTA device is a halogen lamp. lamps, metal halide lamps, xenon arc lamps, carbon arc lamps, high pressure sodium The treated object is irradiated with light (electromagnetic waves) emitted from lamps such as mercury lamps and high-pressure mercury lamps. The GRTA device is a device that uses high-temperature gas to perform heat treatment. do.

[0124] The heat treatment is carried out in the presence of nitrogen, oxygen, or ultra-dry air (with a water content of 20 ppm or less, preferably 1 ppm or less, preferably 10 ppb or less, air), or rare gas (argon, helium, etc. In addition, the above-mentioned nitrogen, oxygen, ultra-dry air, or rare gas may be mixed with hydrogen, water, etc. It is preferable that the material does not contain the above. After heating in an inert gas atmosphere, the material is heated in an oxygen atmosphere. The treatment time is set to 3 minutes to 24 hours.

[0125] In addition, between the substrate 102 and the scanning line 107, the capacitance line 115, and the gate insulating film 127 In the case where a base insulating film is provided, the base insulating film may be made of silicon oxide, silicon oxynitride, or nitride. Silicon oxide, silicon nitride, gallium oxide, hafnium oxide, yttrium oxide, The insulating film may be formed of aluminum oxide, aluminum oxynitride, or the like. As examples, silicon nitride, gallium oxide, hafnium oxide, yttrium oxide, and aluminum oxide By forming the ion implantation layer using a material such as tungsten, impurities, typically alkali metals, water, and water, can be removed from the substrate 102. The diffusion of elements such as silicon into the semiconductor film 111 can be suppressed. Alternatively, it can be formed by using a CVD method.

[0126] Next, an opening 123 is formed in the insulating film 126 to reach the capacitance line 115, and a gate insulating film 127 is formed. After forming the transistor 103, the signal line 109 including the source electrode of the transistor 10 The conductive film 113 including the drain electrode of No. 3, the semiconductor film 118 and the capacitance line 115 are electrically connected. Then, a conductive film 125 is formed (see FIG. 6(B)).

[0127] The opening 123 is formed so that a part of the region of the insulating film 126 overlapping the capacitance line 115 is exposed. A mask is formed by a third photolithography process, and processing is performed using the mask. The mask and the processing are the same as those for the scanning line 107 and the capacitance line 115. This can be done in the same way.

[0128] The signal line 109, the conductive film 113 and the conductive film 125 are A conductive film is formed using a material applicable to the conductive film 125, and a fourth photolithography is formed on the conductive film. The mask is formed by a photolithography process, and the mask is used for processing. The mask and processing are performed in the same manner as the scanning line 107 and the capacitance line 115. This can be done.

[0129] Next, the semiconductor film 111, the semiconductor film 118, the signal line 109, the conductive film 113, and the conductive film 125 An insulating film 128 is formed on the gate insulating film 127, and an insulating film 130 is formed on the insulating film 128. (See FIG. 7A.) ​​The insulating film 128 and the insulating film 130 are formed in succession. In this way, it is preferable that the insulating film 128 and the insulating film 130 are This can prevent impurities from being mixed into the interface.

[0130] The insulating film 128 is formed by a CVD method or a sputtering method using a material applicable to the insulating film 229. The insulating film 130 can be formed by using various film formation methods such as a deposition method. The electrode can be formed using a material applicable to the above.

[0131] When an oxide insulating film that has a low interface state with the semiconductor film 111 is used as the insulating film 229, The insulating film 128 can be formed under the following conditions. The formation of a silicon oxide film or a silicon oxynitride film will be described. The conditions were as follows: the substrate placed in the evacuated processing chamber of the plasma CVD device was heated to 180°C for 4 00°C or less, more preferably 200°C to 370°C or less, and a source gas is introduced into the processing chamber. A deposition gas containing silicon and an oxidizing gas are introduced to keep the pressure in the processing chamber at 20 Pa or less. The pressure in the processing chamber is set to 250 Pa or less, and more preferably 40 Pa or more and 200 Pa or less. This is the condition for supplying high frequency power to the electrodes.

[0132] Representative examples of silicon-containing deposition gases include silane, disilane, trisilane, and fluoride. Silane, etc. Oxidizing gases include oxygen, ozone, nitrous oxide, nitrogen dioxide, etc. There is.

[0133] In addition, by increasing the amount of oxidizing gas to 100 times or more the amount of deposition gas containing silicon, It is possible to reduce the hydrogen content in the insulating film 128 (insulating film 229) and Therefore, the number of dangling bonds contained in the insulating film 128 (insulating film 229) can be reduced. The oxygen that moves from the insulating film 130 (insulating film 231) moves to the insulating film 128 (insulating film 229). Since the insulating film 128 (insulating film 128) may be captured by the dangling bonds contained therein, When the dangling bonds contained in the insulating film 130 (insulating film 23) are reduced, 1) efficiently moves oxygen contained in the semiconductor film 111 to the oxide film 111. It is possible to reduce oxygen vacancies in the semiconductor film. The amount of hydrogen mixed into the film can be reduced, and oxygen vacancies in the oxide semiconductor film can be reduced. It is possible.

[0134] The insulating film 231 is an oxide insulating film including the oxygen excess region or an oxygen insulating film having a stoichiometric composition. When the insulating film 130 is an oxide insulating film containing more oxygen than Note that a silicon oxide film or a silicon oxynitride film can be used as the oxide insulating film here. The formation conditions are as follows: The substrate placed in the processing chamber is heated to 180° C. or higher and 260° C. or lower, more preferably 180° C. or lower. The temperature was kept at 230°C or higher, and the source gas was introduced into the treatment chamber to reduce the pressure in the treatment chamber to 10 The pressure is set to 0 Pa or more and 250 Pa or less, more preferably 100 Pa or more and 200 Pa or less. 0.17W / cm2 at the electrode installed in the room 2 More than 0.5W / cm 2 The following is more preferable: is 0.25W / cm 2 More than 0.35W / cm 2 The aim is to supply the following high frequency power: .

[0135] The source gas for the insulating film 130 may be a source gas that can be used for the insulating film 128 .

[0136] The conditions for forming the insulating film 130 are as follows: high frequency power of the above power density in a processing chamber at the above pressure. By supplying power, the efficiency of decomposition of the source gas in the plasma increases, and the number of oxygen radicals increases. As the oxidation of the source gas progresses, the oxygen content in the insulating film 130 becomes lower than the stoichiometric composition. On the other hand, in the film formed at the above substrate temperature, the bonding strength between silicon and oxygen is Since the oxygen in the film is weak, some of the oxygen in the film is released by the heat treatment in the subsequent process. It contains more oxygen than satisfies the stoichiometric composition, and some of the oxygen is released by heating. An insulating film 128 can be formed on the semiconductor film 111. Therefore, in the process of forming the insulating film 130, the insulating film 128 serves as a protective film for the semiconductor film 111. As a result, even if the insulating film 130 is formed using high-frequency power with a high power density, Damage to the conductive film 111 can be suppressed.

[0137] In addition, by increasing the thickness of the insulating film 130, the amount of oxygen desorbed by heating is increased. Therefore, it is preferable that the insulating film 130 is thicker than the insulating film 128. By providing the insulating film 128, it is possible to improve the coverage even when the insulating film 130 is provided thick. can.

[0138] After forming at least the insulating film 130, a heat treatment is performed to form the insulating film 128 or the insulating film 13 The excess oxygen contained in the oxide semiconductor film 111 is moved to the semiconductor film 111. It is preferable to reduce oxygen vacancies in the film. The dehydrogenation or dehydration of the conductive film 119 having the optical properties is appropriately performed with reference to the details of the heat treatment. It is possible to do so.

[0139] Next, a mask is formed on at least a region of the insulating film 130 overlapping with the light-transmitting conductive film 119. Then, the mask is used to process the insulating film 228 and the insulating film 23 having openings. Note that the mask has an opening where the light-transmitting conductive film 119 is exposed. can use a resist mask formed by a fifth photolithography process, The processing is carried out by one or both of dry etching and wet etching. Note that when the opening is formed by dry etching, the oxide semiconductor film is When exposed to plasma, the oxide semiconductor film is damaged, and defects, typically As a result, a conductive film 119 having low resistance and light transmitting properties is formed. Next, the insulating film 228, the insulating film 230, the conductive film 125, and the light-transmitting conductive film 11 are An insulating film 233 is formed on the substrate 9 (see FIG. 7(B)).

[0140] The insulating film 233 can be formed using a material that can be used for the insulating film 232. The film can be formed by a sputtering method, a CVD method, or the like.

[0141] In the case where the insulating film 233 is formed using a nitride insulating film with a low hydrogen content, the insulating film 233 has the following shape. In this embodiment, a silicon nitride film is used as the nitride insulating film. The formation conditions are as follows: The substrate placed in the treatment chamber is heated to 80°C or higher and 400°C or lower, and more preferably 200°C or higher and 37°C or lower. The temperature is kept below 0°C, and the raw material gas is introduced into the processing chamber to make the pressure in the processing chamber 100 Pa or more. The pressure is set to 250 Pa or less, preferably 100 Pa or more and 200 Pa or less. The object of the present invention is to supply high frequency power to the electrodes.

[0142] The source gas for the insulating film 233 is a deposition gas containing silicon, nitrogen, and ammonia. Representative examples of deposition gases containing silicon include silane, disilane, etc. The nitrogen flow rate is about 10 times that of ammonia. The ratio is preferably 5 to 50 times, more preferably 10 to 50 times. By using ammonia as a source gas, the deposition gas containing silicon and nitrogen are decomposed. This is because ammonia can be heated by plasma energy or thermal energy. The energy generated by dissociation breaks down the bonds and This is because it contributes to breaking down the bonds of nitrogen molecules. The silicon nitride film is formed to prevent the intrusion of impurities such as hydrogen and water from the outside. It is possible.

[0143] An insulating film 233 made of a nitride insulating film is formed by a plasma CVD method or a sputtering method. Then, the semiconductor film 118 is exposed to plasma, and oxygen vacancies are generated in the semiconductor film 118 . In addition, the semiconductor film 118 and the insulating film 233 formed of a nitride insulating film are in contact with each other, Nitrogen and / or hydrogen move from the insulating film 233 to the semiconductor film 118. When the hydrogen contained in the semiconductor enters, electrons, which act as carriers, are generated. The conductive material 118 is a transparent conductive material composed of a metal oxide film having high conductivity and conductive properties. This results in a conductive film 119.

[0144] In addition, after the insulating film 233 is formed, the insulating film 233 may be formed on the conductive film 119 having a light-transmitting property. Heat treatment may be performed in a state of contact. can be further increased.

[0145] Depending on the distance of movement of nitrogen and / or hydrogen from the insulating film 233, the semiconductor film 118 In some cases, part of a region overlapping with the conductive film 125 remains as the oxide semiconductor.

[0146] In addition, a layer is formed between the insulating film 130 and the insulating film 233 by a CVD method using an organic silane gas. A silicon oxide film may be formed.

[0147] In addition, a layer is formed between the insulating film 130 and the insulating film 233 by a CVD method using an organic silane gas. When a silicon oxide film is formed, the insulating film 130 is made of an oxide having a stoichiometric composition. It contains more oxygen than silicon, and forms an insulating oxide film in which some of the oxygen is released when heated. After the film 130 is formed, a heat treatment is performed at 350° C. to remove excess oxygen contained in the insulating film 130. The substrate is then moved to the semiconductor film 111. Next, the above-listed organosilane gas is used, and the substrate temperature is increased to 3 After forming a silicon oxide film by a CVD method with the substrate temperature held at 50° C., a silicon oxide film is formed as an insulating film 233. A nitride insulating film with a low hydrogen content is formed at a temperature of 350°C.

[0148] Next, the insulating film 228, the insulating film 230, and the insulating film 233 are After forming a mask by a sixth photolithography process, the insulating film 228 and the insulating film 23 are 0 and the insulating film 233 are etched to form an insulating film having an opening 117 reaching the conductive film 113. 229, an insulating film 231 and an insulating film 232 are formed (see FIG. 8(A)). can be formed in the same manner as opening 123.

[0149] Finally, the pixel electrode 221 is formed to fabricate the element portion provided on the substrate 102. (See FIG. 8(B)). The pixel electrode 221 is made of the above-listed materials. A conductive film is formed in contact with the conductive film 113 through the opening 117. Next, a seventh conductive film is formed on the conductive film. After forming a mask by the photolithography process of the above, processing is performed using the mask. The pixel electrode 221 can be formed by the above mask and processing. This can be done in the same manner as for the capacitance line 115.

[0150] <Variation 1> In the semiconductor device according to one embodiment of the present invention, the structure of the capacitor can be changed as appropriate. A specific example of this structure will be described with reference to FIG. 9. Note that, in this example, the structure shown in FIG. 2 and FIG. 3 is Only the capacitive element 245, which differs from the capacitive element 205 described above, will be described.

[0151] The gate insulating film 227 is made of an insulating film 225 which is a nitride insulating film and an insulating film 226 which is an oxide insulating film. 26, and at least in a region where a light-transmitting conductive film 119 is provided, By using such a structure, the insulating film 225, which is the nitride insulating film, is provided. Since the insulating film is in contact with the lower surface of the conductive film 119 having light-transmitting properties, the semiconductor film 11 is formed on the insulating film 225. The semiconductor film formed at the same time as step 1 is replaced with a metal oxide film having conductive properties. The conductive film 119 may be a light-transmitting film (see FIG. 9). The dielectric films of 245 are the insulating film 229, the insulating film 231, and the insulating film 232. The film 225 and the insulating film 226 are appropriately made of an insulating film that can be applied to the gate insulating film 127. The insulating film 225 may be the same as the insulating film 232. As a result, the insulating film 129 and the insulating film 131 are etched, and the light-transmitting conductive film 11 Since it is possible to prevent a decrease in the thickness of the semiconductor device 9, the yield is improved compared to the semiconductor device shown in FIG. The performance will improve.

[0152] In the structure shown in FIG. 9, the upper surface of the light-transmitting conductive film 119 is the insulating film 132. That is, in the insulating film 129 and the insulating film 131 shown in FIG. In this case, the region in contact with the light-transmitting conductive film 119 may be removed. The dielectric film 45 is an insulating film 132. The upper and lower surfaces of the conductive film 119 having light transmitting properties are made of nitride. By adopting a structure in which the insulating film is in contact with the nitride insulating film on only one side, the structure can be more efficiently and sufficiently This can increase the conductivity of the conductive film 119 having light-transmitting properties.

[0153] <Variation 2> In the semiconductor device according to one embodiment of the present invention, a light-transmitting electrode that constitutes a capacitor is For example, the aperture ratio can be further increased by changing the connection between the conductive film and the capacitance line. In order to achieve this, a conductive film having light transmitting properties is directly in contact with the capacitance line without a conductive film being interposed therebetween. A specific example of this structure will be described with reference to FIG. Only the capacitance element 145, which is different from the capacitance element 205 described in FIG. 1 is a cross-sectional view of a semiconductor device.

[0154] In the pixel, a light-transmitting conductive film 11 functions as the other electrode of the capacitor 145. 9 is in direct contact with the capacitance line 115 at the opening 143. In contrast, the conductive film 119 having light-transmitting properties and the capacitor line 115 are directly connected to each other without the conductive film 125 being interposed therebetween. Since the conductive film 125 that serves as a light-shielding film is not formed, the aperture ratio of the pixel 141 is further increased. It can be improved.

[0155] <Variation 3> In addition, in the semiconductor device according to one embodiment of the present invention, The configuration of the conductive film and the capacitance line can be changed as appropriate. A specific example of this structure is shown in FIG. In this embodiment, the conductive film 11 having the light-transmitting property described with reference to FIGS. Regarding the conductive film 178 and the capacitor line 176 having light transmitting properties, which are different from those of the capacitor line 115 and the capacitor line 115, We will explain in detail.

[0156] FIG. 11 is a top view of the pixel 172, in which the capacitance line 176 extends in a direction parallel to the signal line 109. The signal line 109 and the capacitance line 176 are provided in a signal line driving circuit 106 ( As shown in FIG. 11, the pixel 172 is electrically connected to the signal The side parallel to the scanning line 107 is longer than the side parallel to the scanning line 109. A line 176 may be provided extending in a direction parallel to the signal line 109 .

[0157] The capacitance element 174 is connected to a capacitance line 176 that is provided extending in a direction parallel to the signal line 109. The capacitor 174 includes a light-transmitting conductive film 178 and a light-transmitting pixel electrode 176. The electrode 221 and a light-transmitting insulating film formed on the transistor 103 as a dielectric film. (Not shown in FIG. 11.) That is, the capacitor 174 has light-transmitting properties.

[0158] The capacitor line 176 can be formed simultaneously with the signal line 109 and the conductive film 113. The wire 176 is provided in contact with the light-transmitting conductive film 178, so that the light-transmitting conductive film 1 It is possible to increase the contact area between the pixel 172 and the capacitance line 176. In this case, the side parallel to the signal line 109 is shorter than the side parallel to the scanning line 107. Therefore, it is possible to reduce the area where the pixel electrode 121 and the capacitance line 176 overlap. You can increase your speaking rate.

[0159] In addition, in FIG. 3, the capacitance line 115 is formed at the same time as the scanning line 107. In order to connect the light-transmitting conductive film 119 to the light-transmitting conductive film 115, an opening is formed in the gate insulating film 127. In order to provide the opening, a photolithography process was required. As shown in FIG. 1, the capacitance line 176 is formed simultaneously with the signal line 109, thereby forming a light-transmitting conductive It is possible to directly connect the conductive film 119 and the capacitance line 176. It is possible to reduce the number of photolithography steps. Thus, a transistor, a pixel electrode connected to the transistor, and a capacitor element can be manufactured. It is possible.

[0160] <Modification 4> In the semiconductor device according to one embodiment of the present invention, an electrode and a capacitor line that constitute a capacitor are transparent. A specific example will be described with reference to FIG. The conductive film 119 and the capacitor line 115 have a light-transmitting property, which is different from the conductive film 119 and the capacitor line 115 described in FIG. 12 is a top view of the pixel 196. In the pixel 96, a light-transmitting conductive film 198 serving as an electrode of a capacitor element 197 and a capacitor line is formed. In the light-transmitting conductive film 198, a light-transmitting conductive film 198 is provided that extends in a direction parallel to the signal line 109. The conductive film 198 has a region that functions as a capacitance line. A region overlapping with the pixel electrode 221 functions as an electrode of the capacitor element 197. The conductive film 198 having a light-transmitting property is formed in the same process as the conductive film 119 having a light-transmitting property shown in FIG. It is possible.

[0161] In addition, the light-transmitting conductive film 198 is formed continuously without any gaps in all the pixels 196 in one row. In the case where the conductive film 198 is provided as a light-transmitting film, the conductive film 198 having light-transmitting properties overlaps with the scan line 107. In some cases, the line 107 may not function as a capacitance line or an electrode of the capacitance element 197 due to a change in potential. Therefore, as shown in FIG. 12, a conductive film 1 having light transmitting properties is formed in each pixel 196. A conductive film 198 having light transmitting properties is provided at a distance from the signal line 109. The conductive film 199 can be formed by utilizing the process of forming the conductive film 113. At this time, it is preferable that the conductive film 198 having a light-transmitting property is connected to the conductive film 199. The non-transparent region overlaps with the pixel electrode 221, forming a light-transmitting conductive film in the region. Since the resistance of the conductive film 198 can be reduced, the conductive film 198 having light transmitting properties can be used as a capacitor line and a capacitor element. It serves as one of the electrodes of 197.

[0162] Although not shown, the conductive film 198 having a light-transmitting property overlaps with the scan line 107. In the case where the potential change of the scanning line 107 does not affect the pixel region, the conductive film 198 having light transmitting property In each of the scanning lines 107 and 196, a conductive film having a light transmitting property is formed so as to overlap with the scanning line 107. That is, the light-transmitting conductive film 198 can be provided in all the pixels 19 in one row. 6, the two can be provided as one continuous piece without any gaps.

[0163] In FIG. 12, a region of the light-transmitting conductive film 198 that functions as a capacitance line is parallel to the signal line 109. The structure extends in the row direction, but the area that functions as a capacitance line extends in a direction parallel to the scanning line 107. In addition, the conductive film 198 having a light-transmitting property may have a region that functions as a capacitance line. When the area extends in a direction parallel to the scanning line 107, the transistor 103 and the capacitor In the element 197, the semiconductor film 111, the conductive film 198 having light-transmitting properties, and the signal line 10 It is necessary to provide an insulating film between the conductive film 9 and the conductive film 113 to electrically isolate them.

[0164] From the above, as in the pixel 196, the electrodes and capacitance lines of the capacitance element provided in the pixel are By providing a light-transmitting conductive film, the aperture ratio of a pixel can be increased.

[0165] <Variation 5> In addition, in the semiconductor device according to one embodiment of the present invention, the configuration of the capacitance line can be changed as appropriate. This structure will be described with reference to FIG. 13. The difference compared to the capacitance line 115 is that the capacitance line is located between two adjacent pixels. .

[0166] FIG. 13 shows a case where a capacitance line is provided between adjacent pixels in the extension direction of a signal line 409. In addition, a capacitance line is provided between adjacent pixels in the extension direction of the scanning line 437. It is also possible to adopt a configuration in which

[0167] FIG. 13 shows the upper part of a pixel 401_1 and a pixel 401_2 adjacent to each other in the extension direction of a signal line 409. FIG.

[0168] The scanning line 407_1 and the scanning line 407_2 are parallel to each other and connected to the signal line 409. The scanning lines 407_1 and 407_2 are disposed so as to extend in directions substantially perpendicular to each other. A capacitance line 415 is provided in parallel to the scanning line 407_1 and the scanning line 407_2. Note that the capacitor line 415 is connected to the capacitor 405_1 provided in the pixel 401_1 and the The pixel 401_1 and the pixel 401_2 are connected to a capacitor 405_2 provided in the pixel 401_1 and the pixel 401 The top shape of the element _2 and the arrangement positions of the components are symmetrical with respect to the capacitance line 415.

[0169] The pixel 401_1 includes a transistor 403_1 and a A pixel electrode 421_1 and a capacitor element 405_1 are provided.

[0170] The transistor 403_1 is provided in a region where the scanning line 407_1 and the signal line 409 intersect. The transistor 403_1 is a semiconductor having at least a channel formation region. A film 411_1, a gate electrode, a gate insulating film (not shown in FIG. 13), and a source electrode. In addition, in the scan line 407_1, the semiconductor film 411_1 and The overlapping region functions as a gate electrode of the transistor 403_1. The region overlapping with the semiconductor film 411_1 serves as a source electrode of the transistor 403_1. In the conductive film 413_1, a region overlapping with the semiconductor film 411_1 functions as a transistor. The conductive film 413_2 and the pixel electrode 421_1 function as a drain electrode of the pixel electrode 403_1. are connected at the opening 417_1.

[0171] The capacitor 405_1 is connected to the capacitor line 415 through a conductive film 425 provided in an opening 423. The capacitor 405_1 is electrically connected to a light-transmitting conductive film 419_1 and A pixel electrode 421_1 having a light transmitting property and a dielectric film formed on the transistor 403_1. The capacitor is made of a transparent insulating film (not shown in FIG. 13). The element 405_1 has a light-transmitting property.

[0172] The pixel 401_2 includes a transistor 403_2 and a A pixel electrode 421_2 and a capacitor element 405_2 are provided.

[0173] The transistor 403_2 is provided in a region where the scanning line 407_2 and the signal line 409 intersect. The transistor 403_2 is a semiconductor having at least a channel formation region. A film 411_2, a gate electrode, a gate insulating film (not shown in FIG. 13), and a source electrode. In addition, in the scan line 407_2, the semiconductor film 411_2 and The overlapping region functions as a gate electrode of the transistor 403_2. The region overlapping with the semiconductor film 411_2 serves as a source electrode of the transistor 403_2. In the conductive film 413_2, a region overlapping with the semiconductor film 411_2 functions as a transistor. The conductive film 413_2 and the pixel electrode 421_2 function as a drain electrode of the pixel electrode 421_2. connect at opening 417_2.

[0174] The capacitor 405_2 is formed by a conductive film provided in an opening 423, similarly to the capacitor 405_1. The capacitor 405_2 is electrically connected to the capacitor line 415 through a light-transmitting a conductive film 419_2 having a light-transmitting property, a pixel electrode 421_2 having a light-transmitting property, and A light-transmitting insulating film (not shown in FIG. 13) formed over the transistor 403_2 That is, the capacitor 405_2 has a light-transmitting property.

[0175] Note that the transistor 403_1, the transistor 403_2, and the capacitor 405_ The cross-sectional structures of the transistor 103 and the capacitor 405_2 are the same as those of the transistor 103 and the capacitor 405_2 shown in FIG. Since it is similar to the quantum element 205, its description is omitted here.

[0176] In the top view, a capacitance line is provided between two adjacent pixels, and the capacitance line included in each pixel is By connecting the capacitance elements and the capacitance lines, it is possible to reduce the number of capacitance lines. As a result, it is possible to further increase the aperture ratio of the pixels compared to a structure in which a capacitance line is provided for each pixel. It is.

[0177] <Variation 6> In the semiconductor device according to one embodiment of the present invention, the shape of a transistor provided in a pixel is 2, 4, 11, 12, and 13, the transistor shapes are not limited to those shown in FIG. For example, in the case of a transistor, The source electrode is U-shaped (C-shaped, U-shaped, or horseshoe-shaped), and the conductive film including the drain electrode is The transistor may have a shape that surrounds the transistor. Even if the area is small, it is possible to secure a sufficient channel width, and the transistor conducts This makes it possible to increase the amount of drain current (also called on-current) that flows at certain times.

[0178] <Variation 7> In the above-described transistor, the oxide semiconductor film serves as a gate insulating film and a source A transistor is disposed between the signal line 109 including a drain electrode and the conductive film 113 including a drain electrode. Instead, the semiconductor film is connected to the signal line including the source electrode and the drain electrode. A transistor located between the conductive film including the insulating film 229 and the insulating film 229 can be used.

[0179] <Variation 8> Although a channel-etched transistor has been described as the transistor described above, Instead, a channel protection type transistor can be used. By providing the semiconductor film 111, the surface of the semiconductor film 111 is protected from the etching used in the process of forming the signal lines and the conductive film. The semiconductor film 111 and the channel protection film are not exposed to the etching gas and impurities between the semiconductor film 111 and the channel protection film are reduced. As a result, the leakage current flowing between the source electrode and the drain electrode of the transistor can be reduced. It is possible to reduce the flow.

[0180] <Variation 9> In addition, the above-described transistor is a transistor having one gate electrode. However, a transistor having two gate electrodes opposed to each other via a semiconductor film 111 is used. It is possible.

[0181] The transistor is a transistor 103 having a conductor formed on the insulating film 232 thereof. The conductive film overlaps at least a channel formation region of the semiconductor film 111. By providing the conductive film at a position overlapping with a channel formation region of the semiconductor film 111, It is preferable that the potential is set to the lowest potential of the video signal input to the signal line 109. On the surface of the semiconductor film 111 facing the conductive film, a current flows between the source electrode and the drain electrode. It is possible to control the current flowing through the transistor, thereby reducing the variation in the electrical characteristics of the transistor. In addition, by providing a conductive film, the change in the surrounding electric field is applied to the semiconductor film 111. This can reduce the effect of the damage and improve the reliability of the transistor.

[0182] The conductive film provided on the insulating film 232 includes the scanning lines 107, the signal lines 109, the pixel electrodes 121, The same materials and manufacturing methods as those described above can be appropriately used to form the same.

[0183] As described above, the semiconductor film formed in the same formation process as the semiconductor film included in the transistor is made of nitrogen. A metal oxide having conductive properties, i.e., a transparent insulating film, is provided in contact with the metal oxide. By using a conductive film having the following structure as an electrode of a capacitor, the aperture ratio can be increased. It can be 50% or more, preferably 55% or more, and more preferably 60% or more. At the same time, a semiconductor device having a capacitor element with increased charge capacity can be manufactured. As a result, a semiconductor device with excellent display quality can be obtained.

[0184] In addition, oxygen vacancies are reduced in an oxide semiconductor film, which is a semiconductor film included in a transistor. Since impurities such as hydrogen are reduced, the semiconductor device according to one embodiment of the present invention can be favorably The semiconductor device has good electrical characteristics and reduced power consumption.

[0185] Note that the structure described in this embodiment mode may be appropriately combined with structures described in other embodiments. It can be used.

[0186] <Modification 10> In the method for manufacturing the transistor, a method for forming the conductive film 119 having a light-transmitting property is After the step of FIG. 6B, the semiconductor film 111 is covered and the semiconductor film 118 is exposed. Next, the semiconductor film 118 is treated with a rare gas, a mixed gas of hydrogen and a rare gas, or a rare Plasma generated in an atmosphere of gas and ammonia mixture, ammonia gas, nitrogen gas, etc. By exposing the semiconductor film 118 to a laser beam, a nitride insulating film is formed on the semiconductor film 118 as shown in FIG. The light-transmitting conductive film 119 can be formed without going through this step.

[0187] Alternatively, in the above-described method for manufacturing a transistor, a method for forming the light-transmitting conductive film 119 As a method, after the process of FIG. 7(A), the semiconductor film 111 is covered and the semiconductor film 118 is exposed. Next, the semiconductor film 118 is etched with a mixed gas of a rare gas, hydrogen, and a rare gas, The plasma generated in an atmosphere of a mixture of rare gas and ammonia, ammonia gas, nitrogen gas, etc. By exposing the semiconductor film 118 to the plasma, hydrogen, nitrogen, etc. diffuse into the semiconductor film 118 through the insulating film 130. As shown in FIG. 7B, the semiconductor film 118 is transparent without a step of forming a nitride insulating film. A conductive film 119 having the above structure can be formed.

[0188] When the semiconductor film 118 is exposed to the plasma, an oxide semiconductor is formed as the semiconductor film 118. The oxide semiconductor film is damaged, and defects, typically oxygen vacancies, are generated in the oxide semiconductor film. As a result, a light-transmitting conductive film 119 with reduced resistivity is formed.

[0189] (Embodiment 2) This embodiment describes a semiconductor device according to one embodiment of the present invention, which has a structure different from that of the above embodiment. The semiconductor device will be described with reference to the drawings. In this embodiment, a liquid crystal display device is taken as an example. In addition, the semiconductor device according to one embodiment of the present invention will be described. The device is different from the above embodiment in that a light-transmitting conductive film is included in a capacitor. In the semiconductor device described in this embodiment, the semiconductor For a similar structure to that of the device, the above embodiment can be referred to.

[0190] <Configuration of Semiconductor Device> A specific configuration of a pixel 301 provided in a pixel portion of a liquid crystal display device described in this embodiment mode. An example will be described. A top view of a pixel 301 is shown in FIG. 14. The pixel 301 shown in FIG. 14 has the following features: The pixel 301 includes a capacitance element 305, which is connected to the capacitance line 115 and the signal line 10. The capacitor 305 is provided in a region surrounded by a conductive film 9. The capacitor element 305 is electrically connected to the capacitor line 115 through the insulating film 125. A conductive film 319 having a light-transmitting property, a pixel electrode 221 having a light-transmitting property, and a transistor 14. The insulating film 103 is formed on the insulating film 103. That is, the capacitor 305 has a light-transmitting property.

[0191] A light-transmitting conductive film 319 is used as an electrode of the capacitor element. The capacitance element 305 can be formed large (with a large area). Typically, it is 50% or more, preferably 55% or more, and more preferably 60% or more. It is possible to obtain a semiconductor device having an increased charge capacity.

[0192] Next, cross-sectional views taken along dashed lines A1-A2 and B1-B2 in FIG. Shown in Figure 15.

[0193] The cross-sectional structure of the pixel 301 is as follows. A gate insulating film 127 is formed on the scanning line 107. A semiconductor film 111 is provided on a region of the gate insulating film 127 that overlaps with the scanning line 107. A light-transmitting conductive film 319 is provided over the gate insulating film 127. A source electrode of the transistor 103 is formed on the semiconductor film 111 and the gate insulating film 127. A signal line 109 including a drain electrode of the transistor 103 and a conductive film 113 including a drain electrode of the transistor 103 are provided. In addition, a light-transmitting conductive film 319 and a capacitor line 115 are formed over the gate insulating film 127. A conductive film 125 is provided on the gate insulating film 127, on the signal line 109, and on the semiconductor device 106. Over the conductive film 111, the conductive film 113, the conductive film 125, and the light-transmitting conductive film 319 The insulating film 129 and the insulating film 131 function as protective insulating films for the transistor 103, and the insulating film 132 and the insulating film 133 function as protective insulating films for the transistor 103. The insulating film 129, the insulating film 131, and the insulating film 132 are provided with a conductive film. An opening 117 is provided that reaches the film 113, and a pixel electrode is formed on the opening 117 and the insulating film 132. The electrode 221 is provided. The substrate 102, the scanning line 107, and the gate insulating film 127 A base insulating film may be provided between them.

[0194] In this configuration, one of the pair of electrodes of the capacitor element 305 is the pixel electrode 121. The other electrode is a light-transmitting conductive film 319 provided between the pair of electrodes. The dielectric films are the insulating film 129, the insulating film 131, and the insulating film 132.

[0195] The light-transmitting conductive film 319 is a semiconductor film formed at the same time as the semiconductor film 111. A metal oxide that has conductive properties and is doped with an element (dopant) that increases the conductivity. That is, the light-transmitting conductive film 319 is an oxide semiconductor film that constitutes the semiconductor film 111. The metal element of the alloy includes a dopant. The dopant may be hydrogen, boron, nitrogen, or the like. From fluorine, aluminum, phosphorus, arsenic, indium, tin, antimony and rare gas elements The dopant concentration in the light-transmitting conductive film 319 is 1× 10 19 atoms / cm 3 More than 1×10 22 atoms / cm 3 It is preferable that In this way, the electrical conductivity of the light-transmitting conductive film 319 can be increased to 10 S / cm or more. 1000 S / cm or less, preferably 100 S / cm to 1000 S / cm Therefore, the light-transmitting conductive film 319 can be made to function sufficiently as an electrode of the capacitor 305. This can be done.

[0196] <Method for manufacturing semiconductor device> Next, a manufacturing method of the semiconductor device in this embodiment mode will be described with reference to FIGS. I will explain this in more detail.

[0197] First, the scanning line 107 and the capacitance line 115 are formed on the substrate 102. An insulating film 126 to be processed into a gate insulating film 127 is formed on the capacitance line 127. The semiconductor film 111 and the semiconductor film 118 are formed on the substrate 126 (see FIG. 16A). The steps up to this point can be carried out with reference to the first embodiment.

[0198] Next, a dopant is added to the semiconductor film 118 to form a light-transmitting conductive film 319. An opening 123 is formed in the insulating film 126 to reach the capacitance line 115, and a gate insulating film 127 is formed. Then, the signal line 109 including the source electrode of the transistor 103 and the drain of the transistor 103 are connected to The conductive film 113 including the doped electrode, the conductive film 319 having light-transmitting properties, and the capacitor line 115 are electrically connected to each other. A connecting conductive film 125 is formed (see FIG. 16(B)).

[0199] The method of adding a dopant to the semiconductor film 118 is to mask the region other than the semiconductor film 118. By using the mask, hydrogen, boron, nitrogen, fluorine, aluminum, phosphorus, arsenic In the present invention, one or more dopants selected from the group consisting of indium, tin, antimony and rare gas elements are added. The doping is performed by ion implantation or ion doping. Instead of the doping method, the semiconductor film 118 is exposed to plasma containing the dopant. A dopant may be added. After the dopant is added, a heat treatment may be performed. The heat treatment is preferably performed to dehydrogenate the semiconductor film 111 and the light-transmitting conductive film 319 or The dehydration can be appropriately carried out by referring to the details of the heat treatment.

[0200] The process of adding the dopant is performed on the signal line 109, the conductive film 113, and the conductive film 125. In that case, the signal line 109 of the conductive film 319 having light-transmitting properties may be formed after the formation of the conductive film 319. The dopant is not added to the conductive film 113 and the region in contact with the conductive film 125 .

[0201] Next, the gate insulating film 127, the signal line 109, the semiconductor film 111, the conductive film 113, and the conductive film 1 An insulating film 128 is formed over the insulating film 128. An insulating film 130 is formed, and an insulating film 133 is formed on the insulating film 130 (see FIG. 17(A)). ) This step can be performed with reference to the first embodiment.

[0202] Next, an opening reaching the conductive film 113 is formed in the insulating film 128, the insulating film 130 and the insulating film 133. An opening 117 is formed, and an insulating film 129, an insulating film 131, and an insulating film 132 are formed (FIG. 17 (see FIG. 1B), a pixel electrode 221 is formed in contact with the conductive film 113 through the opening 117. (See FIG. 15.) This step can also be performed with reference to the first embodiment. do.

[0203] Through the above steps, the semiconductor device of this embodiment mode can be manufactured.

[0204] As described above, the semiconductor film formed in the same formation process as the semiconductor film included in the transistor Metal oxides with conductive properties, i.e., transparent, are obtained by adding a gallium arsenide. By using a conductive film having a high capacitance as an electrode of a capacitor, the aperture ratio can be increased and the charge capacity can be increased. As a result, a semiconductor device having a capacitor element having a high display quality can be manufactured. A semiconductor device having such a structure can be obtained.

[0205] In addition, since both of the pair of electrodes of the capacitor 305 are conductive, Even if the area is reduced, a sufficient charge capacity can be obtained. Since the ratio is 80 to 90%, the area of ​​the conductive film 319 having light-transmitting properties is reduced, and the pixel 301 By providing a region where the light-transmitting conductive film 319 is not formed in the backlight In other words, the transmittance of light emitted from a light source such as a backlight can be increased. The brightness of the light source can be reduced, and the power consumption of the semiconductor device can be reduced. .

[0206] In addition, oxygen vacancies are reduced in an oxide semiconductor film, which is a semiconductor film included in a transistor. Impurities such as hydrogen are reduced. As a result, the transistor has normally-on characteristics. This can suppress the occurrence of the problem, thereby improving the electrical characteristics and reliability of the semiconductor device. At the same time, power consumption of the semiconductor device can be reduced.

[0207] The configurations shown in this embodiment may be used in conjunction with the configurations shown in other embodiments and their modified examples. They can be used in any suitable combination.

[0208] (Embodiment 3) In this embodiment mode, a conductive film having a light-transmitting property different from that in the embodiment modes 1 and 2 is used. The method of forming the semiconductor device will be described with reference to FIG.

[0209] In this embodiment, the semiconductor film is irradiated with electromagnetic waves such as visible light, ultraviolet light, and X-rays. The semiconductor film is characterized by being made of a metal oxide having electrical conductivity by increasing the electrical conductivity of the semiconductor film. A method for manufacturing the conductive film will be described with reference to FIGS.

[0210] As shown in FIG. 6(A), similarly to the first embodiment, a scanning electrode including a gate electrode is formed on a substrate 102. Next, the substrate 102, the scanning line 1 including the gate electrode, and the capacitance line 115 are formed. An insulating film 126 is formed on the insulating film 126. 111 and a semiconductor film 118 are formed.

[0211] Next, electromagnetic waves such as visible light, ultraviolet light, and X-rays are applied to the semiconductor film 118 from the substrate 102 side. In this process, the semiconductor film 111 is irradiated with light so as to shield the scanning line 107 including the gate electrode. Therefore, the electromagnetic waves are not irradiated and the electrical conductivity does not increase.

[0212] When the semiconductor film 118 is irradiated with electromagnetic waves, defects are generated in the semiconductor film 118. The defects become carrier paths, the electrical conductivity increases, and the metal oxide becomes conductive. A metal oxide can be used as a light-transmitting conductive film which is an electrode of a capacitor.

[0213] In the present embodiment, unlike the first embodiment, the insulating film 128 and the insulating film 13 In addition, unlike the second embodiment, the step of etching a part of the semiconductor film There is no need to form a mask in order to add a dopant to 118. It is possible to reduce the number of photomasks, simplifying the manufacturing process and reducing costs. It is.

[0214] (Embodiment 4) In this embodiment, FFS (Fringe Field Switching) is used to align liquid crystal molecules using a lateral electric field. A semiconductor device according to one embodiment of the present invention will be described with reference to a liquid crystal display device of a field switching mode. In the semiconductor device described in the present embodiment, For a structure similar to that of the semiconductor device described in the above embodiment, the above embodiment can be referred to.

[0215] <Configuration of Semiconductor Device> A top view of a pixel 501 described in this embodiment is shown in FIG. 18(B) is a top view of the pixel 501 with the common electrode 521 omitted, and FIG. 18(A) is a top view of the pixel 501 with the common electrode 521 omitted. 5 is a top view of a pixel 501 provided with a pole 521. FIG.

[0216] The pixel 501 shown in FIG. 18 includes a transistor 103 and a The capacitor 505 includes a light-transmitting conductive film 519 and a light-transmitting A common electrode 521 formed of a conductive film having In other words, the capacitance element 505 is The light-transmitting conductive film 519 is a conductive film 1 of the transistor 103. 13 and functions as a pixel electrode. That is, by applying an electric field between the common electrode and the pixel electrode, a conductive film having light transmission property is formed. A capacitor element is formed in an overlapping region of the conductive film 519, the insulating film having light-transmitting properties, and the common electrode 521. This function allows the liquid crystal molecules to be oriented in a direction parallel to the substrate. LCDs in this mode have a better viewing angle and provide higher image quality.

[0217] Next, a cross-sectional view of the substrate 102 taken along the dashed line A1-A2 in FIG. 18(B) is shown in FIG. show.

[0218] The cross-sectional structure of the pixel 501 in this embodiment is as follows. A scanning line 107 including the gate electrode of the transistor 103 is provided. A gate insulating film 127 is provided. The area of ​​the gate insulating film 127 that overlaps with the scanning line 107 A semiconductor film 111 is provided on the gate insulating film 127. A transistor is formed on the semiconductor film 111 and the gate insulating film 127. A signal line 109 including a source electrode of the transistor 103 and a signal line 109 including a drain electrode of the transistor 103 A conductive film 113 is provided. The conductive film 113 including the drain electrode has a light-transmitting property. The signal line 517 is connected to the conductive film 519 and functions as a pixel electrode. 109, the semiconductor film 111, and the conductive film 113 as a protective insulating film of the transistor 103. Insulating films 229, 231, and 232 that function as insulating films are provided. An insulating film 232 is provided on the conductive film 519 having a common electrode. The common electrode 521 is not separated for each pixel in the pixel portion. , are provided continuously. Note that the substrate 102, the scanning line 107, and the gate insulating film 127 A base insulating film may be provided between them.

[0219] The light-transmitting conductive film 519 has the light-transmitting property described in any of Embodiments 1 to 3. The common electrode 521 can be formed in the same manner as the conductive film described in the embodiment 1. The pixel electrode 221 can be formed using the same material.

[0220] As in the capacitor 505 in this embodiment, a light-transmitting conductive film 519 is By connecting the conductive film 113 of the transistor, the conductive film 113 and the light-transmitting The conductive film 519 having the above structure can be directly connected to the transistor 103 and the capacitor It is possible to improve the flatness of the element 505. In addition, a light-transmitting element having no capacitance line is used. By making the common electrode 521 function as a capacitance line, the aperture ratio of the pixel 501 can be further increased. It is possible.

[0221] (Embodiment 5) In this embodiment, a transistor included in the semiconductor device described in the above embodiment is One embodiment that can be applied to an oxide semiconductor film that is a semiconductor film in a capacitor will be described. do.

[0222] The oxide semiconductor film may be an amorphous oxide semiconductor, a single crystal oxide semiconductor, or a polycrystalline oxide semiconductor. In addition to semiconductors, oxide semiconductors with crystalline parts (C Axis Aligned Cry Stalline Oxide Semiconductor (CAAC-OS) It is preferable that the above is done.

[0223] The CAAC-OS film is one of the oxide semiconductor films that has multiple crystal parts. The crystal part is small enough to fit inside a cube with one side less than 100 nm. The crystal parts contained in the OS film are in the form of cubes with one side less than 10 nm, 5 nm, or 3 nm. The CAAC-OS film has a smaller defect density than a microcrystalline oxide semiconductor film. The CAAC-OS film has a low density of recessed states. .

[0224] The CAAC-OS film was observed under a transmission electron microscope (TEM). When observed using a quartz crystal microscope, clear boundaries between the crystals were observed. It is not possible to confirm the grain boundary. It can be said that the AAC-OS film is less susceptible to the decrease in electron mobility caused by grain boundaries.

[0225] The CAAC-OS film was observed by TEM from a direction roughly parallel to the sample surface (cross-sectional TEM observation). When the metal atoms are observed, it can be confirmed that they are arranged in layers in the crystal part. Each of the layers has a surface on which the CAAC-OS film is to be formed (also called a surface on which the film is to be formed) or a top surface having irregularities. The shape of the CAAC-OS film reflects this, and the CAAC-OS films are aligned parallel to the surface on which the film is formed or the upper surface.

[0226] On the other hand, the CAAC-OS film was observed by TEM from a direction roughly perpendicular to the sample surface (plane T EM observation revealed that metal atoms were arranged in triangular or hexagonal shapes in the crystals. However, no regularity was observed in the arrangement of metal atoms between different crystal regions. stomach.

[0227] Cross-sectional and planar TEM observations revealed that the crystals in the CAAC-OS film had an orientation. It can be seen that...

[0228] X-ray diffraction (XRD) of CAAC-OS film When the structure is analyzed using the device, for example, InGaZnO 4 CAAC-OS with crystals of In the out-of-plane analysis of the film, the diffraction angle (2θ) peaked at around 31°. This peak may appear in InGaZnO 4It is assigned to the (009) plane of the crystal. Therefore, the crystals of the CAAC-OS film have a c-axis orientation, and the c-axis is generally aligned on the surface on which the film is formed or on the upper surface. It can be seen that it is oriented in a substantially vertical direction.

[0229] On the other hand, in-p X-rays are incident on the CAAC-OS film from a direction approximately perpendicular to the c-axis. In the lane method, a peak may appear at 2θ around 56°. InGaZnO 4 It is attributed to the (110) plane of the InGaZnO crystal. 4 Single crystal of acid In the case of a nitride semiconductor film, 2θ is fixed at around 56°, and the normal vector of the sample surface is the axis (φ axis). When the sample is rotated and analyzed (φ scan), a crystal plane equivalent to the (110) plane is detected. In contrast, in the case of the CAAC-OS film, six peaks are observed, which are assigned to Even when φ is fixed at around 56° and scanned, no clear peak appears.

[0230] From the above, it is considered that the orientation of the a-axis and b-axis is uniform between different crystal regions in the CAAC-OS film. Although it is irregular, it has a c-axis orientation, and the c-axis is parallel to the normal vector of the surface to be formed or the upper surface. Therefore, the layered arrangement confirmed by the cross-sectional TEM observation mentioned above is consistent with the above. Each layer of aligned metal atoms is a plane parallel to the ab plane of the crystal.

[0231] The crystalline portion is formed when the CAAC-OS film is formed or when a crystallization process such as a heat treatment is performed. As described above, the c-axis of the crystal is aligned along the surface on which the CAAC-OS film is formed or along the surface on which the CAAC-OS film is formed. The orientation is parallel to the normal vector of the top surface. When the crystal orientation is changed by etching, the c-axis of the crystal is aligned with the surface on which the CAAC-OS film is formed or the may not be parallel to the normal vector of the top surface.

[0232] In addition, the crystallinity in the CAAC-OS film does not have to be uniform. When the crystalline part of the film is formed by crystal growth from the vicinity of the top surface of the CAAC-OS film, The area near the surface may have a higher crystallinity than the area near the surface on which it is formed. When impurities are added to the AC-OS film, the crystallinity of the region to which the impurities are added changes, resulting in a partial In some cases, regions of differing crystallinity may be formed.

[0233] In addition, InGaZnO 4 Out-of-plane crystallographic structure of CAAC-OS film In the analysis by the method, in addition to the peak at 2θ near 31°, a peak also appeared at 2θ near 36°. The peak at 2θ of around 36° may be due to the c-axis orientation in some parts of the CAAC-OS film. The CAAC-OS film contains crystals that do not have the 2θ value of about 31°. It is preferable that the spectrum shows a peak at 2θ of about 36° and does not show a peak at 2θ of about 36°.

[0234] There are three methods for forming CAAC-OS.

[0235] In the first method, an oxide semiconductor film is formed at a film formation temperature of 100° C. or more and 450° C. or less. In this way, the c-axis of the crystal part included in the oxide semiconductor film is aligned along a normal vector of the surface on which the film is formed or along a normal vector of the surface. This is a method for forming crystal parts that are aligned in a direction parallel to the normal vector.

[0236] The second method is to form an oxide semiconductor film to a small thickness, and then heat the film at a temperature of 200° C. to 700° C. By performing heat treatment, the c-axis of a crystal part included in the oxide semiconductor film is aligned with the normal vector of the formation surface. This is a method for forming crystals aligned in a direction parallel to the normal vector of the crystal or surface.

[0237] The third method is to form a thin oxide semiconductor film as a first layer, and then heat the film at 200° C. or higher for 700 The oxide semiconductor film is then formed by performing a heat treatment at or below 1000°C. The c-axis of the crystal part contained in the film is parallel to the normal vector of the surface on which it is formed or the normal vector of the surface. This is a method for forming crystal parts that are aligned in a certain direction.

[0238] A transistor that uses CAAC-OS for an oxide semiconductor film can be irradiated with visible light or ultraviolet light. Therefore, the change in electrical characteristics due to the application of CAAC-OS to the oxide semiconductor film is small. The transistor has good reliability.

[0239] In addition, CAAC-OS uses a polycrystalline oxide semiconductor sputtering target. It is preferable to form the film by a sputtering method. When ions collide with the sputtering target, the crystalline regions in the sputtering target are transformed from the ab plane to The sputtered particles are then cleaved from the ab plane to obtain plate-like or pellet-like sputtered particles with a surface parallel to the ab plane. In this case, the plate-like or pellet-like sputtered particles may peel off. By reaching the deposition surface while maintaining the crystalline state, the CAAC-OS can be deposited. Cut.

[0240] In addition, in order to form a CAAC-OS film, the following conditions are preferably applied.

[0241] By reducing the amount of impurities mixed in during film formation, it is possible to prevent the crystal state from being destroyed by impurities. For example, the concentration of impurities (hydrogen, water, carbon dioxide, nitrogen, etc.) present in the deposition chamber can be In addition, the impurity concentration in the deposition gas may be reduced. A deposition gas having a temperature of −80° C. or lower, preferably −100° C. or lower is used.

[0242] In addition, by increasing the heating temperature (for example, the substrate heating temperature) of the surface to be film-formed during film formation, Specifically, the temperature of the surface on which the film is to be formed increases, and then the sputtered particles begin to migrate. The temperature is set to 100° C. or higher and 740° C. or lower, preferably 150° C. or higher and 500° C. or lower. By increasing the temperature of the surface during deposition, plate-like or pellet-like sputtering particles When it reaches the surface on which the film is to be formed, migration occurs on the surface, resulting in sputtering. The flat surface of the particle adheres to the surface on which the film is to be formed.

[0243] In addition, by increasing the oxygen ratio in the deposition gas and optimizing the power, plasma damage during deposition is reduced. The oxygen ratio in the deposition gas is preferably 30% by volume or more, and more preferably 100% by volume or more. Expressed as volume percent.

[0244] As an example of a sputtering target, an In-Ga-Zn-O compound target is used. The details are shown below.

[0245] InO X powder, GaO Y Powder and ZnO Z The powders are mixed in a specified number of moles and then pressurized. By heat treatment at a temperature between 1000 and 1500℃, polycrystalline In-Ga The pressure treatment is performed while cooling (or cooling naturally). The reaction may be performed while heating, or while heating. X, Y, and Z are any positive numbers. Here, the predetermined molar ratio is, for example, InO X powder, GaO YPowder and ZnO Z Powder , 2:2:1, 8:4:3, 3:1:1, 1:1:1, 4:2:3 or 3:1:2. The type of powder and the molar ratio of the powder to be mixed depend on the sputtering target to be prepared. The setting can be changed as appropriate depending on the kit.

[0246] The oxide semiconductor film may have a structure in which a plurality of oxide semiconductor films are stacked. For example, The oxide semiconductor film is a stack of a first oxide semiconductor film and a second oxide semiconductor film. The oxide semiconductor film and the second oxide semiconductor film may each be made of a metal oxide having a different atomic ratio. For example, the first oxide semiconductor film may include an oxide containing two kinds of metals or an oxide containing three kinds of metals. The first oxide semiconductor film is formed by using one of the oxides containing four kinds of metals. Semiconductor film and oxide containing two different metals, oxide containing three different metals, oxide containing four different metals An oxide containing the following may also be used.

[0247] The oxide semiconductor film has a two-layer structure including a first oxide semiconductor film and a second oxide semiconductor film. The elements may be the same, but the atomic ratio of the elements may be different. The atomic ratio of the second oxide semiconductor film is In:Ga:Zn=3:1:2. The atomic ratio of the first oxide semiconductor film may be In:Ga:Zn=1:1:1. The atomic ratio of the second oxide semiconductor film was In:Ga:Zn=2:1:3. The atomic ratio of each oxide semiconductor film may be set to 1:3:2. This includes a fluctuation of plus or minus 20% in numerical ratios.

[0248] At this time, the first oxide semiconductor film and the second oxide semiconductor film, whichever is closer to the gate electrode ( The atomic number ratio of In to Ga in the oxide semiconductor film on the channel side) may be set such that In ≧ Ga. Also The atomic number ratio of In to Ga in the oxide semiconductor film on the side far from the gate electrode (back channel side) may be set such that In < Ga. With these laminated structures, a transistor with a high field-effect mobility can be fabricated. On the other hand, by setting the atomic number ratio of In to Ga in the oxide semiconductor film on the side close to the gate electrode (channel side) to In < Ga and the atomic number ratio of In to Ga in the oxide semiconductor film on the back channel side to In ≧ Ga, the variation amount of the threshold voltage due to the change over time of the transistor and reliability tests can be reduced.

[0249] The first oxide semiconductor film having an atomic number ratio of In:Ga:Zn = 1:3:2 can be formed by a sputtering method using an oxide target having an atomic number ratio of In:Ga:Zn = 1:3:2. It can be formed with the substrate temperature at room temperature using argon or a mixed gas of argon and oxygen as the sputtering gas. The second oxide semiconductor film having an atomic number ratio of In:Ga:Zn = 3:1:2 can be formed in the same manner as the first oxide semiconductor film using an oxide target having an atomic number ratio of In:Ga:Zn = 3:1:2.

[0250]

[0251] Alternatively, the oxide semiconductor film may have a three-layer structure, the constituent elements of the first to third oxide semiconductor films may be the same, and their respective atomic number ratios may be different. The configuration in which the oxide semiconductor film has a three-layer structure will be described with reference to FIG. 20.

[0251] The transistor shown in FIG. 20 has a first oxide semiconductor film 199a, a second oxide semiconductor film 199b, and a third oxide semiconductor film 199c laminated in this order from the gate insulating film 127 side. The materials constituting the first oxide semiconductor film 199a and the third oxide semiconductor film 199c are The fee is InM 1x Zinc y O z (x≧1, y>1, z>0, M 1 =Ga, Hf, etc.) However, the first oxide semiconductor film 199a and the third oxide semiconductor film 199b are made of a material that can be used. When Ga is included in the material that constitutes 99c, the ratio of Ga included is high, specifically I nM 1X Zinc Y O Z If the material can be expressed as X=10 or more, there is a risk of powder being generated during film formation. Yes, it is inappropriate.

[0252] The material forming the second oxide semiconductor film 199b is InM 2x Zinc y O z (x≧ Use materials that can be expressed with the formula (1, y≧x, z>0, M2=Ga, Sn, etc.).

[0253] The conduction band of the first oxide semiconductor film 199a and the conduction band of the third oxide semiconductor film 199c are In comparison, the second oxide semiconductor film 199b has a well-type conduction band that is the deepest from the vacuum level. Materials for the first, second, and third oxide semiconductor films are appropriately selected so as to form the structure.

[0254] In the oxide semiconductor film, silicon and carbon, which are group 14 elements, act as donors. Therefore, when silicon or carbon is contained in the oxide semiconductor film, the oxide semiconductor film Therefore, silicon and carbon contained in each oxide semiconductor film become n-type. The concentration of is 3×10 18 / cm 3 Less than or equal to 3×10 17 / cm 3 The following applies. In particular, In order to prevent a large amount of Group 14 elements from being mixed into the second oxide semiconductor film 199b, The semiconductor film 199a and the third oxide semiconductor film 199c are connected to the second oxide semiconductor film 199b, which serves as a carrier path. It is preferable that the first oxide semiconductor film 199b is sandwiched between the first oxide semiconductor film 199b and the second oxide semiconductor film 199c. The conductive film 199a and the third oxide semiconductor film 199c are made of a group 14 element such as silicon or carbon. The oxide semiconductor film 199c can also be referred to as a barrier film that prevents the oxide semiconductor film 199b from being mixed with the second oxide semiconductor film 199b.

[0255] For example, the atomic ratio of the first oxide semiconductor film 199a is set to In:Ga:Zn=1:3:2. The atomic ratio of the second oxide semiconductor film 199b is In:Ga:Zn=3:1:2. The atomic ratio of the oxide semiconductor film 199c in No. 3 may be In:Ga:Zn=1:1:1. Note that the atomic ratio of the third oxide semiconductor film 199c is In:Ga:Zn=1:1:1. The film can be formed by sputtering using an oxide target.

[0256] Alternatively, the first oxide semiconductor film 199a may be formed of In:Ga:Zn having an atomic ratio of 1:3:2. The second oxide semiconductor film 199b has an atomic ratio of In:Ga:Z The oxide semiconductor film has a structure in which n is 1:1:1 or In:Ga:Zn is 1:3:2. The oxide semiconductor film 199c is an oxide semiconductor having an atomic ratio of In:Ga:Zn=1:3:2. A three-layer structure including a membrane may also be used.

[0257] The first to third oxide semiconductor films 199a to 199c are formed using the same elements. Therefore, the second oxide semiconductor film 199b has a thin film at the interface with the first oxide semiconductor film 199a. In particular, the defect level (trap level) is , the defect states at the interface between the gate insulating film 127 and the first oxide semiconductor film 199a are larger than those at the interface between the gate insulating film 127 and the first oxide semiconductor film 199a. Therefore, by stacking oxide semiconductor films as described above, This can reduce the amount of variation in threshold voltage due to deterioration over time or due to reliability testing.

[0258] In addition, the conduction band of the first oxide semiconductor film 199a and the conduction band of the third oxide semiconductor film 199c are The conduction band of the second oxide semiconductor film 199b is the deepest from the vacuum level compared to the conduction band. The materials of the first, second, and third oxide semiconductor films are appropriately selected so as to form a well-type structure. By doing so, it is possible to increase the field effect mobility of the transistor and This can reduce the amount of variation in threshold voltage due to deterioration over time of the transistor or due to reliability testing.

[0259] In addition, the first to third oxide semiconductor films 199a to 199c each have a crystalline structure. Different oxide semiconductors may be used. A conductor, an amorphous oxide semiconductor, and a CAAC-OS may be appropriately combined. In addition, any one of the first to third oxide semiconductor films 199a to 199c When an amorphous oxide semiconductor is used, the internal stress and external stress of the oxide semiconductor film are reduced. This reduces the variation in transistor characteristics and also reduces the deterioration over time and reliability testing of transistors. Therefore, the amount of variation in the threshold voltage can be reduced.

[0260] At least the second oxide semiconductor film 199b which can be a channel formation region is made of CAA The oxide semiconductor film on the back channel side is preferably C-OS. In this embodiment, the third oxide semiconductor film 199c is amorphous or CAAC-OS. By adopting such a structure, it is preferable that the transistor is prevented from deterioration over time or from being subjected to a reliability test. The amount of variation in the threshold voltage can be reduced.

[0261] Note that the structure described in this embodiment mode may be appropriately combined with structures described in other embodiments. It can be used.

[0262] (Embodiment 6) A semiconductor device having a display function using the transistor and the capacitor described as examples in the above embodiment In addition, a semiconductor device including a transistor can be manufactured. A part or the whole of the operating circuit is integrated on the same substrate as the pixel section to form a system on panel. In this embodiment, the transistor shown as an example in the above embodiment can be used. An example of the display device will be described with reference to FIGS. 21 to 23. FIG. 22(B) is a cross-sectional view showing the cross-sectional configuration of the portion indicated by the dashed line MN in FIG. 21(B). 22. Note that in FIG. 22, only a part of the structure of the pixel unit is shown.

[0263] In FIG. 21A, a pixel portion 902 provided on a first substrate 901 is surrounded by a A sealant 905 is provided and the semiconductor device is sealed with a second substrate 906. ) is different from the region surrounded by the sealant 905 on the first substrate 901. A signal line driver formed of a single crystal semiconductor or a polycrystalline semiconductor on a separately prepared substrate is provided in the region where the signal line driver is formed. A signal line driver circuit 903 and a scanning line driver circuit 904 are mounted on the display panel. 3. Various signals and potentials given to the scanning line driver circuit 904 or the pixel portion 902 are transmitted through the FPC (Flexible printed circuit)918a, FPC918b is being supplied.

[0264] In FIG. 21B and FIG. 21C, a pixel portion 90 provided on a first substrate 901 A sealant 905 is provided so as to surround the insulating film 902 and the scanning line driver circuit 904. A second substrate 906 is provided on the pixel portion 902 and the scanning line driver circuit 904. The pixel portion 902 and the scanning line driver circuit 904 are formed by a first substrate 901 and a sealing material 905. The display element is sealed with the second substrate 906. In FIG. 9C, the region surrounded by the sealant 905 on the first substrate 901 is Signals formed in different regions using single crystal semiconductors or polycrystalline semiconductors on a separately prepared substrate A signal line driver circuit 903 is mounted. In FIG. 21B and FIG. 21C, Various signals and power supplies to the driver circuit 903, the scanning line driver circuit 904, or the pixel portion 902 The position is provided by FPC918.

[0265] In addition, in FIG. 21B and FIG. 21C, a signal line driver circuit 903 is separately formed. 9, the scanning line 902 is mounted on the first substrate 901, but the present invention is not limited to this configuration. The driver circuit may be formed separately and mounted, or may be mounted as a part of the signal line driver circuit or the scanning line driver circuit. Only a part of it may be formed separately and mounted.

[0266] The method of connecting the separately formed drive circuit is not particularly limited, and may be any method such as COG ( hip on glass method, wire bonding method, or TAB (Tape The Automated Bonding method can be used. This is an example in which a signal line driver circuit 903 and a scanning line driver circuit 904 are mounted by the COG method. FIG. 21B shows an example in which a signal line driver circuit 903 is mounted by the COG method. C) is an example in which a signal line driver circuit 903 is mounted by the TAB method.

[0267] The display device includes a panel in which a display element is sealed, and a controller for the panel. This includes modules in which ICs, etc., including lasers, are mounted.

[0268] In this specification, the term "display device" refers to an image display device or a display device. In addition, it can function as a light source (including a lighting device) instead of a display device. Connectors, such as FPC or TCP-mounted modules, and TCP-mounted modules A module with a printed wiring board or a display element is mounted with an IC (integrated circuit board) by the COG method. ) is also included in the display device.

[0269] In addition, the pixel portion and the scan line driver circuit provided on the first substrate have a plurality of transistors. To this end, the transistor described in the above embodiment can be applied.

[0270] Examples of display elements provided in the display device include liquid crystal elements (also called liquid crystal display elements), light-emitting elements, and the like. A light-emitting element (also called a light-emitting display element) can be used. A light-emitting element emits light by applying a current or a voltage. This category includes elements whose brightness is controlled by a specific factor, such as inorganic EL (Electroluminescent) devices. Luminescence elements, organic electroluminescence elements, etc. Also, electronic ink, etc. A display medium in which the contrast is changed by electrical action can also be used. 1 shows an example of a liquid crystal display device using a liquid crystal element as a display element.

[0271] The liquid crystal display device shown in FIG. 22(A) is a vertical electric field type liquid crystal display device. has a connection terminal electrode 915 and a terminal electrode 916. The electrode 916 is electrically connected to a terminal of the FPC 918 via an anisotropic conductive material 919. It is being done.

[0272] The connection terminal electrode 915 is formed from the same conductive film as the first electrode 930, and the terminal electrode 916 The source and drain electrodes of the transistors 910 and 911 are formed of the same conductive film. is.

[0273] In addition, a pixel portion 902 and a scanning line driver circuit 904 provided on a first substrate 901 are A transistor 910 included in a pixel portion 902 has a plurality of transistors. The transistor 910 and the transistor 911 included in the circuit 904 are illustrated. An insulating film corresponding to the insulating film 229 and the insulating film 231 shown in Embodiment 1 is formed over the transistor 911. An insulating film 924 and an insulating film 934 corresponding to the insulating film 232 are provided. Reference numeral 23 denotes an insulating film that functions as a base film.

[0274] In this embodiment, the transistor 910 is the transistor shown in the above embodiment. In addition, the conductive film 927, the insulating film 924, and the first The capacitor 926 is formed using the electrode 930. The transistor 91 is connected to a capacitance wiring 929 via an electrode 928. 0, the source electrode and the drain electrode of the transistor 911 are formed of the same material and in the same process. The capacitance wiring 929 is connected to the gate electrodes of the transistors 910 and 911. The capacitor 926 is formed using the same material and process as in Embodiment 1. However, the capacitance element shown in the embodiment may be used as appropriate. do.

[0275] The transistor 910 provided in the pixel portion 902 is electrically connected to a display element. The display element is not particularly limited as long as it can display an image. It can be used.

[0276] The liquid crystal element 913, which is a display element, includes a first electrode 930, a second electrode 931, and a liquid crystal layer. The liquid crystal layer 908 is sandwiched between insulating films 932 which function as alignment films. An insulating film 933 is provided on the second substrate 906 side. The first electrode 930 and the second electrode 931 are overlapped with the liquid crystal layer 908 interposed therebetween. is.

[0277] A first electrode and a second electrode (a pixel electrode, a common electrode, and a counter electrode) for applying a voltage to a display element In the case of a reflective electrode, the direction of the light to be extracted, the location of the electrodes, and the pattern of the electrodes are determined. The translucency or reflectivity can be selected depending on the turn structure.

[0278] The first electrode 930 and the second electrode 931 are the same as the pixel electrode 221 and the corresponding electrode shown in the first embodiment. The same material as that of the counter electrode 154 can be used as appropriate.

[0279] The spacer 935 is a columnar spacer obtained by selectively etching an insulating film. In order to control the distance (cell gap) between the first electrode 930 and the second electrode 931, It should be noted that a spherical spacer may also be used.

[0280] When liquid crystal elements are used as display elements, thermotropic liquid crystal, low molecular weight liquid crystal, high molecular weight liquid crystal, etc. Liquid crystal, polymer dispersed liquid crystal, ferroelectric liquid crystal, antiferroelectric liquid crystal, etc. can be used. These liquid crystal materials can exhibit cholesteric, smectic, cubic, and chromatic phases depending on the conditions. It shows an isotropic phase, an isotropic phase, etc.

[0281] Alternatively, a liquid crystal that exhibits a blue phase without using an alignment film may be used. When the temperature of the cholesteric liquid crystal is increased, the cholesteric phase transitions to the isotropic phase. The blue phase appears only in a narrow temperature range, so it is necessary to improve the temperature range. In order to improve the alignment, a liquid crystal composition containing a chiral agent is used for the liquid crystal layer. The organic resin is composed of an organic resin, and the organic resin contains hydrogen or water, etc. There is a risk that the electrical characteristics of the transistors in such semiconductor devices may be degraded. By using a blue phase for the layer 160, it is possible to obtain a semiconductor device according to one embodiment of the present invention without using an organic resin. A semiconductor device can be manufactured, and a highly reliable semiconductor device can be obtained.

[0282] The first substrate 901 and the second substrate 906 are fixed by a sealant 925. The molding material 925 may be an organic resin such as a thermosetting resin or a photosetting resin. The sealant 925 is in contact with the insulating film 924. It is equivalent to material 905.

[0283] In addition, in liquid crystal display devices, black matrices (light-shielding films), polarizing members, and phase difference members Optical members (optical substrates) such as anti-reflection members are provided as appropriate. Circularly polarized light produced by a retardation substrate may be used. Either may be used.

[0284] In addition, since transistors are easily damaged by static electricity, etc., a protection circuit for protecting the drive circuit is It is preferable to provide a protection circuit using a non-linear element.

[0285] Next, a liquid crystal display device of the in-plane switching mode will be described with reference to FIG. B) is an example of a liquid crystal display device in an FFS mode, which is an example of a horizontal electric field type. The structure of this display device, which is different from that of the in-plane switching liquid crystal display device shown in FIG.

[0286] In the liquid crystal display device shown in FIG. 22(B), the connection terminal electrode 915 is The terminal electrode 916 is formed of the same material and in the same process as the transistors 910 and 911. It is formed from the same material and in the same process as the source electrode and the drain electrode.

[0287] The liquid crystal element 943 includes a first electrode 940 and a second electrode 941 formed on the insulating film 924. The liquid crystal element 943 includes a capacitor and a liquid crystal layer 908. The first electrode 940 may have a structure similar to that of the first electrode 205 shown in FIG. The materials shown in the first electrode 930 can be used appropriately. The shape of the second electrode 941 is a comb shape, a step shape, a ladder shape, etc. The conductive film can be formed in a manner similar to that of the light-transmitting conductive film described in any of Embodiments 1 to 3. An insulating film 924 is provided between the first electrode 940 and the second electrode 941.

[0288] The second electrode 941 is connected to a common wiring 946 via an electrode 945. 45 is the same as the source electrode and drain electrode of the transistor 910 and the transistor 911 The common wiring 946 is formed of a conductive film. The gate electrode is formed of the same material and in the same process. Although the capacitive element shown in the first embodiment has been used in the description, the capacitive element shown in the other embodiments may be used as appropriate. The element can be used.

[0289] FIG. 23 shows a second liquid crystal display device provided on the substrate 906 in the liquid crystal display device shown in FIG. A common connection portion (pad portion) for electrically connecting to the electrode 931 is formed on the substrate 901. Here is an example.

[0290] The common connection portion is disposed at a position overlapping with the seal material for bonding the substrate 901 and the substrate 906. and is electrically connected to the second electrode 931 via conductive particles contained in the sealing material. Or, provide a common connection part in a place that does not overlap with the sealing material (excluding the pixel part) and A paste containing conductive particles is provided separately from the sealing material so as to overlap the connecting portion, forming a second electrode 93. 1 may be electrically connected to

[0291] FIG. 23(A) is a cross-sectional view of the common connection portion, which corresponds to IJ in the top view shown in FIG. 23(B). Correct.

[0292] The common potential line 975 is provided on the gate insulating film 922 and is connected to the transistor 9 shown in FIG. 10. It is made of the same material and in the same process as the source electrode 971 or the drain electrode 973 of FIG.

[0293] The common potential line 975 is covered with the insulating film 924 and the insulating film 934. The insulating film 934 has a plurality of openings at positions overlapping the common potential lines 975. The transistor 910 is connected to one of the source electrode 971 and the drain electrode 973 of the transistor 910. The contact hole connecting the electrode 930 is fabricated in the same process.

[0294] In addition, the common potential line 975 and the common electrode 977 are connected at the opening. is provided on the insulating film 934 and is the same as the connection terminal electrode 915 and the first electrode 930 of the pixel portion. It is made from the same materials and through the same processes.

[0295] In this manner, the common connection portion is formed in the same manufacturing process as the switching element of the pixel portion 902. It can be manufactured.

[0296] The common electrode 977 is an electrode that comes into contact with the conductive particles contained in the sealing material, and is disposed on the substrate 906. An electrical connection is made with the second electrode 931 of the first electrode 931 .

[0297] 23C, a common potential line 985 is connected to the gate of a transistor 910. They may be made of the same material and in the same process as the electrodes.

[0298] In the common connection portion shown in FIG. 23C, the common potential line 985 is The gate insulating film 922 and the insulating film 924 are provided below the insulating film 934. , and the insulating film 934 has a plurality of openings at positions overlapping the common potential line 985. , one of the source electrode 971 or the drain electrode 973 of the transistor 910 and the first electrode 9 After etching the insulating film 924 in the same process as the contact hole connecting the gate 30, The gate insulating film 922 is selectively etched to form the insulating film 922 .

[0299] In addition, the common potential line 985 and the common electrode 987 are connected at the opening. is provided on the insulating film 924 and is the same as the connection terminal electrode 915 and the first electrode 930 of the pixel portion. It is made from the same materials and through the same processes.

[0300] As described above, by using the transistor and the capacitor described in the above embodiment, It is possible to provide a semiconductor device having a capacitance element with an increased charge capacity while increasing the charge transfer rate. As a result, a semiconductor device with excellent display quality can be obtained.

[0301] In addition, oxygen vacancies are reduced in an oxide semiconductor film, which is a semiconductor film included in a transistor. Since impurities such as hydrogen are reduced, the semiconductor device according to one embodiment of the present invention can be favorably This results in a semiconductor device having excellent electrical characteristics and reduced power consumption.

[0302] Note that the structure described in this embodiment mode may be appropriately combined with structures described in other embodiments. It can be used.

[0303] (Embodiment 7) The semiconductor device according to one embodiment of the present invention can be applied to various electronic devices (including game machines). The electronic equipment includes a television set (television or television receiver) (also called a monitor), computer monitors, digital cameras, digital video cameras , digital photo frames, mobile phones, portable game machines, personal digital assistants, audio playback devices , gaming machines (pachinko machines, slot machines, etc.), and game cabinets. An example of the vessel is shown in FIG.

[0304] FIG. 24A shows a table 9000 having a display section. A display unit 9003 is built into the housing 9001, and an image is displayed on the display unit 9003. It is possible to support the housing 9001 with four legs 9002. The housing 9001 also includes a power cord 9005 for supplying power.

[0305] The semiconductor device described in any of the above embodiments can be used for the display portion 9003. Therefore, the display quality of the display portion 9003 can be improved.

[0306] The display unit 9003 has a touch input function. By touching the display button 9004 displayed on the screen with a finger or the like, the screen can be operated or information can be input. It can also communicate with and control other home appliances, improving picture quality. It may also be a control device that controls other home appliances by surface manipulation. For example, If a semiconductor device having a sensor function is used, the display portion 9003 can have a touch input function. It is possible.

[0307] In addition, the screen of the display unit 9003 can be fixed to the floor by a hinge provided in the housing 9001. It can also be placed vertically and used as a television set. A large-screen television set will take up a lot of free space, but it can be placed on a table. If the display unit is built into the device, the space in the room can be used more effectively.

[0308] FIG. 24B shows a television device 9100. A display unit 9103 is incorporated in a housing 9101, and an image is displayed on the display unit 9103. In this example, the housing 9101 is supported by a stand 9105. The configuration shown is as follows.

[0309] The television device 9100 can be operated using an operation switch provided on the housing 9101 or a separate remote control. This can be done by using a remote control operation device 9110. The channel and volume can be controlled by the 9109, and the display 9103 shows The remote control device 9110 can control the video. A display unit 9107 for displaying information output from the device 9110 may be provided.

[0310] A television device 9100 shown in FIG. 24(B) includes a receiver, a modem, and the like. The television device 9100 can receive general television broadcasts using a receiver. Furthermore, by connecting to a wired or wireless communication network via a modem, One-way (from sender to receiver) or two-way (between sender and receiver, or between receivers) It is also possible to carry out information communication.

[0311] The semiconductor device described in any of the above embodiments can be used for the display portions 9103 and 9107. This makes it possible to improve the display quality of the television device.

[0312] FIG. 24C shows a computer 9200, which includes a main body 9201, a housing 9202, a display unit 9 203, keyboard 9204, external connection port 9205, pointing device 920 6, etc.

[0313] The semiconductor device described in any of the above embodiments can be used for the display portion 9203. Therefore, the display quality of the computer 9200 can be improved.

[0314] FIG. 25(A) and FIG. 25(B) show a tablet-type terminal that can be folded in two. 9631a, the tablet terminal is in an open state. 9631b, a display mode changeover switch 9034, a power switch 9035, a power saving mode It has a mode changeover switch 9036, a fastener 9033, and an operation switch 9038.

[0315] The semiconductor device described in any of the above embodiments includes a display portion 9631a and a display portion 9631b. Therefore, it is possible to improve the display quality of tablet devices. Cut.

[0316] A part of the display unit 9631a can be used as a touch panel area 9632a. By touching the operation keys 9638 displayed on the display unit 96, data can be input. In 31a, as an example, half of the area has a display function only, and the other half The display unit 96 has a touch panel function, but is not limited to this. The entire area of ​​the display unit 931a may have a touch panel function. The entire surface of 631a is made to display keyboard buttons to serve as a touch panel, and the display section 9631b is made to display It can be used as a display screen.

[0317] In addition, in the display unit 9631b, as in the display unit 9631a, The part of the touch panel can be the area 9632b of the touch panel. Touch the area where the mode display switch button 9639 is displayed with your finger or a stylus. A keyboard button can be displayed on the display portion 9631b.

[0318] In addition, the touch panel area 9632a and the touch panel area 9632b are simultaneously You can also use touch input.

[0319] A display mode changeover switch 9034 is used to change the display orientation, such as vertical or horizontal. You can choose between black and white and color display. The 9036 is a tablet-type device that detects external light during use using a built-in light sensor. The tablet device has a light sensor, which can adjust the display brightness to suit the amount of light. In addition to the sensor, other detection devices such as gyro, acceleration sensor, etc. that detect the inclination are also included. It may be built-in.

[0320] FIG. 25A shows an example in which the display area of ​​the display portion 9631b is the same as that of the display portion 9631a. However, there is no particular limitation, and one size may be different from the other size. The quality of the display may also be different. For example, one display panel may provide a higher resolution display than the other. It may also be used as a rule.

[0321] FIG. 25(B) shows the tablet terminal in a closed state. The tablet terminal includes a housing 9630 and a solar cell 9 25B, the charge / discharge control circuit 96 As an example of the 34, a configuration having a battery 9635 and a DC-DC converter 9636 is described below. This is shown.

[0322] In addition, since the tablet device can be folded in half, the case 9630 can be folded when not in use. Therefore, the display portions 9631a and 9631b can be protected. This makes it possible to provide a tablet device that is highly durable and reliable even when used for a long period of time.

[0323] In addition, the tablet terminals shown in Figs. 25(A) and 25(B) can be used in various Functions that display information (still images, videos, text images, etc.), calendars, dates, or times A function to display information on the display unit, and a function to input or edit information displayed on the display unit. It has input functions, functions to control processing by various software (programs), etc. It is possible.

[0324] The solar cell 9633 attached to the surface of the tablet device supplies power to the touch panel. The solar cell 9633 can supply the solar cell 9633 with the following components: The battery 9635 can be efficiently charged by providing the battery 9635 on one or both sides of the housing 9630. The battery 9635 may be a lithium ion battery. The use of the above has the advantage of enabling miniaturization.

[0325] The configuration and operation of the charge / discharge control circuit 9634 shown in FIG. A block diagram is shown in FIG. 25(C) and will be explained. FIG. 25(C) shows a solar cell 9633, a battery 9 635, DC-DC converter 9636, converter 9637, switches SW1 to SW3 , a display unit 9631, a battery 9635, a DC-DC converter 963 6. The converter 9637 and the switches SW1 to SW3 are configured to perform the charge / discharge control shown in FIG. 25(B). This corresponds to the circuit 9634 .

[0326] First, an example of operation when power is generated by the solar cell 9633 due to external light will be described. The power generated by the solar cell is converted to a voltage to charge the Battery 9635. The CDC converter 9636 increases or decreases the voltage. When power is being used from the solar cell 9633, switch SW1 is turned on and the converter The voltage is increased or decreased to the voltage required for the display unit 9631 by the display unit 9637. When not displaying on the 9631, turn SW1 off and SW2 on to power the battery. It would be best to configure it to charge the 9635.

[0327] The solar cell 9633 is shown as an example of a power generating means, but is not limited thereto. , and other power generation methods such as piezoelectric elements and thermoelectric conversion elements (Peltier elements) For example, the battery 9635 may be charged. A non-contact power transmission module that transmits and receives power and charges, or a combination of other charging methods This may also be configured.

[0328] Note that the structure described in this embodiment mode may be appropriately combined with structures described in other embodiments. It can be used. EXAMPLES

[0329] In this example, the resistance of the oxide semiconductor film and the multilayer film is measured using FIGS. 26 and 27. He explains.

[0330] First, the structure of the sample will be described with reference to FIG.

[0331] FIG. 26A is a top view of Samples 1 to 4, and is a cross-sectional view taken along dashed line A1-A2. The top views of samples 1 to 4 are the same, and the cross-sectional views are the same. The cross-sectional views are different because the laminated structures of the two surfaces are different. A cross-sectional view of sample 1 is shown in FIG. 26(C), and a cross-sectional view of sample 3 and sample 4 is shown in FIG. 26(D). .

[0332] In the sample 1, an insulating film 1903 is formed on a glass substrate 1901, and an insulating film 1903 is formed on the insulating film 1903. An insulating film 1904 is formed, and an oxide semiconductor film 1905 is formed over the insulating film 1904. In addition, conductive films 1907 and 1909 functioning as electrodes are provided on both ends of the oxide semiconductor film 1905. The oxide semiconductor film 1905 and the conductive films 1907 and 1909 are covered with insulating films 1910 and 1911. The insulating films 1910 and 1911 are provided with openings 1913 and 1915. In the openings, conductive films 1907 and 1909 are exposed.

[0333] In the sample 2, an insulating film 1903 is formed on a glass substrate 1901, and an insulating film is formed on the insulating film 1903. An insulating film 1904 is formed, and an oxide semiconductor film 1905 is formed over the insulating film 1904. In addition, both ends of the oxide semiconductor film 1905 are covered with conductive films 1907 and 1909 which function as electrodes. The oxide semiconductor film 1905 and the conductive films 1907 and 1909 are covered with an insulating film 1911. The insulating film 1911 has openings 1917 and 1919. At the opening, the conductive films 1907 and 1909 are exposed.

[0334] In the samples 3 and 4, an insulating film 1903 is formed on a glass substrate 1901, and an insulating film 19 An insulating film 1904 is formed on the insulating film 1903, and a multilayer film 1906 is formed on the insulating film 1904. In addition, both ends of the multilayer film 1906 are covered with conductive films 1907 and 1909 that function as electrodes. The multilayer film 1906 and the conductive films 1907 and 1909 are covered with an insulating film 1911. 911 is provided with openings 1917 and 1919, , the conductive films 1907 and 1909 are exposed.

[0335] In this manner, in each of Samples 1 to 4, a semiconductor layer was formed on the oxide semiconductor film 1905 or the multilayer film 1906. The structure of the insulating film in contact with the oxide semiconductor film 1905 is different. In Sample 2, the oxide semiconductor film 1905 is in contact with the insulating film 1911. In sample 4, the multilayer film 1906 and the insulating film 1911 are in contact with each other.

[0336] Next, the method for preparing each sample will be described.

[0337] First, a method for preparing Sample 1 will be described.

[0338] On a glass substrate 1901, an insulating film 1903 is formed by a plasma CVD method. A silicon nitride film with a thickness of nm was formed.

[0339] Next, on the insulating film 1903, an insulating film 1904 is formed by a plasma CVD method. A silicon oxynitride film having a thickness of nm was formed.

[0340] Next, a metal oxide target ( In:Ga:Zn=1:1:1) was used, and a 35 nm thick In- A Ga-Zn oxide film (hereinafter also referred to as an IGZO film) was formed. An etching process is performed using a mask formed by a roughening process, and the oxide semiconductor film 190 5 was formed.

[0341] Next, a thick insulating film 1903 and an oxide semiconductor film 1905 are formed by a sputtering method. A 50 nm thick tungsten film, a 400 nm thick aluminum film, and a 100 nm thick tungsten film were After laminating the titanium films in order, they are etched using a mask formed by a photolithography process. A conductive film 1907 and a conductive film 1909 were formed by performing a plating treatment.

[0342] Next, the insulating film 1904, the oxide semiconductor film 1905, the conductive film 1907, and the conductive film 190 On the substrate 9, a silicon oxynitride film having a thickness of 450 nm is formed as an insulating film 1910 by a plasma CVD method. After the film was formed, it was heat-treated for 1 hour in a mixed atmosphere of nitrogen and oxygen at 350°C. .

[0343] Next, on the insulating film 1910, an insulating film 1911 is formed by a plasma CVD method. A silicon nitride film with a thickness of nm was formed.

[0344] Next, after providing a mask on the insulating film 1911 by a photolithography process, Then, an etching process is performed to form openings 1913 and 1914 in the insulating film 1910 and the insulating film 1911. 15 was formed.

[0345] Sample 1 was prepared by the above steps.

[0346] Next, a method for preparing Sample 2 will be described.

[0347] The insulating film 1903, the oxide semiconductor film 1905, the conductive film 1907, and the conductive film 19 On the insulating film 1910, a 450 nm thick oxide nitride silicon film is formed by plasma CVD. After the silicon film was formed, it was heat-treated for 1 hour in a mixed atmosphere of nitrogen and oxygen at 350°C. After that, the insulating film 1910 was removed.

[0348] Next, the insulating film 1904, the oxide semiconductor film 1905, the conductive film 1907, and the conductive film 190 On the substrate 9, a silicon nitride film having a thickness of 50 nm is formed as an insulating film 1911 by a plasma CVD method. A film was formed.

[0349] Next, after providing a mask on the insulating film 1911 by a photolithography process, Then, an etching process was performed to form openings 1917 and 1919 in the insulating film 1911 .

[0350] Sample 2 was prepared by the above steps.

[0351] Next, a method for preparing Sample 3 will be described.

[0352] In Sample 3, a multilayer film 1906 was used instead of the oxide semiconductor film 1905 in Sample 2. The layer film 1906 is formed by depositing a metal oxide target (In:Ga:Zn = 1:3:2), a 10 nm thick IGZO film was formed by sputtering, followed by A metal oxide target (In:Ga:Zn=1:1:1) was used for the sputtering method. A 10 nm thick IGZO film was then deposited by a metal oxide target (In:Ga: Zn=1:3:2) and a 10 nm thick IGZO film was formed by sputtering. After that, an etching process was performed using a mask formed by a photolithography process. Thus, a multilayer film 1906 was formed.

[0353] Sample 3 was prepared by the above steps.

[0354] Next, a method for preparing Sample 4 will be described.

[0355] In Sample 4, a multilayer film 1906 was used instead of the oxide semiconductor film 1905 in Sample 2. In addition, sample 4 is different from sample 3 in the film thickness of the IGZO film that constitutes the multilayer film 1906 . The multilayer film 1906 is formed by depositing a metal oxide target (In:Ga:Z n=1:3:2) and a 20 nm thick IGZO film was formed by sputtering. Next, sputtering was performed using a metal oxide target (In:Ga:Zn=1:1:1). A 15 nm thick IGZO film was then deposited by a metal oxide target (In:Ga :Zn=1:3:2) and a 10 nm thick IGZO film was formed by sputtering. Then, etching was performed using a mask formed by a photolithography process. This resulted in the formation of a separated multilayer film 1906.

[0356] Sample 4 was prepared by the above steps.

[0357] Next, the oxide semiconductor film 1905 and the multilayer film 1906 provided in Samples 1 to 4 were The sheet resistance was measured. In sample 1, the openings 1913 and 1915 were filled with a probe. The sheet resistance of the oxide semiconductor film 1905 was measured by contacting the oxide semiconductor film 1905 with a sintered body. In FIG. 4, a probe is brought into contact with the openings 1917 and 1919, and an oxide semiconductor The sheet resistance of the film 1905 and the multilayer film 1906 was measured. In the compound semiconductor film 1905 and the multilayer film 1906, the conductive film 1907 and the conductive film 190 The width of the opposing electrodes 9 was 1 mm, and the distance was 10 μm. The conductive film 1907 was at ground potential, and 1 V was applied to the conductive film 1909 .

[0358] The sheet resistances of Samples 1 to 4 are shown in FIG.

[0359] The sheet resistance of sample 1 is about 1×10 11 The sheet resistance of sample 2 was The sheet resistance of sample 3 was 4410 Ω / sq. The sheet resistance of Sample 4 was 2930 Ω / sq.

[0360] In this way, the difference in the insulating film in contact with the oxide semiconductor film 1905 and the multilayer film 1906 Therefore, the oxide semiconductor film 1905 and the multilayer film 1906 have different sheet resistances.

[0361] When the sheet resistances of the above-mentioned Samples 1 to 4 are converted into resistivities, Sample 1 has a resistivity of 3 .9×10 5 Ωcm, sample 2 is 9.3×10 -3 Ωcm, sample 3 is 1.3×10 -2 Ωcm, sample 4 is 1.3×10 -2 It was Ωcm.

[0362] Sample 1 is a silicon oxynitride film that is in contact with an oxide semiconductor film 1905 and is used as an insulating film 1910. A silicon nitride film is formed on the insulating film 1911. On the other hand, Samples 2 to 4 each have an oxide semiconductor film 1905 and a multilayer film 1906. A silicon nitride film used as an insulating film 1911 is formed in contact with the oxide. The nitride semiconductor film 1905 and the multilayer film 1906 are formed of silicon nitride used as an insulating film 1911. When the oxide semiconductor film 1905 and the multilayer film 1906 are provided in contact with each other, defects, typically In the oxide semiconductor film 1, oxygen vacancies are formed, and hydrogen contained in the silicon nitride film is absorbed into the oxide semiconductor film 1. The oxide semiconductor film 190 moves or diffuses into the oxide semiconductor film 1905 and the multilayer film 1906. 5, and the electrical conductivity of the multilayer film 1906 is improved.

[0363] For example, in the case where an oxide semiconductor film is used for a channel formation region of a transistor, It is preferable that a silicon oxynitride film is provided in contact with the oxide semiconductor film so as to form a As a light-transmitting conductive film used for an electrode of a quantum well element, an oxide film as shown in Samples 2 to 4 is used. It is preferable to provide a silicon nitride film in contact with the nitride semiconductor film or the multilayer film. By using this composition, an oxide semiconductor film or The multilayer film and the oxide semiconductor film or multilayer film used for the electrode of the capacitor are manufactured in the same process. Furthermore, the resistivity of the oxide semiconductor film and the multilayer film can be changed.

[0364] Next, the sheet resistance of the samples 2 and 3 stored in a high-temperature and high-humidity environment, The sheet resistance of the sample was measured when the measurement temperature was changed. The conditions are explained below. Note that, in some cases, Sample 2 and Sample The conditions used for sample 3 were different from those for sample 2. Therefore, the structure is the same as sample 2 and sample 3, and the fabrication The samples under different conditions are designated as sample 2a and sample 3a, respectively.

[0365] First, a method for preparing the sample 2a will be described.

[0366] An insulating film 1903 and an insulating film 1904 were formed on a glass substrate 1901 .

[0367] A metal oxide target (In: A 35 nm thick IGZO film was formed by sputtering using a Ga:Zn=1:1:1 After that, the film was etched using a mask formed by a photolithography process. After the treatment, heat treatment is performed at 350° C. or 450° C. to form an oxide semiconductor film 1905. did.

[0368] A 50 nm thick insulating film was formed over the insulating film 1903 and the oxide semiconductor film 1905 by a sputtering method. After stacking a 400 nm thick titanium film and a 400 nm thick copper film in order, a photolithography process is performed. The conductive film 1907 and the conductive film 1909 are then etched using a mask formed from the above. was formed.

[0369] Next, the insulating film 1904, the oxide semiconductor film 1905, the conductive film 1907, and the conductive film 190 On the substrate 9, a silicon oxynitride film having a thickness of 450 nm is formed as an insulating film 1910 by a plasma CVD method. After the film was formed, it was heat-treated for 1 hour in a mixed atmosphere of nitrogen and oxygen at 350°C. .

[0370] Next, the insulating film 1904, the oxide semiconductor film 1905, the conductive film 1907, and the conductive film 190 On the substrate 9, a silicon nitride film having a thickness of 50 nm is formed as an insulating film 1911 by a plasma CVD method. The silicon nitride film was formed at a temperature of 220° C. or 350° C.

[0371] Next, after providing a mask on the insulating film 1911 by a photolithography process, Then, an etching process is performed to form openings 1913 and 1914 in the insulating film 1910 and the insulating film 1911. 15 was formed.

[0372] Through the above steps, sample 2a was fabricated.

[0373] Next, a method for preparing the sample 3a will be described.

[0374] In the sample 3a, a multilayer film 1906 was used instead of the oxide semiconductor film 1905 in the sample 2a. The multilayer film 1906 is formed by depositing a metal oxide target (In:Ga: Zn=1:1:1) and a 10 nm thick IGZO film was formed by sputtering. Then, a metal oxide target (In:Ga:Zn=1:3:2) was used for sputtering. A 10 nm thick IGZO film was then formed by photolithography. After etching using the mask formed by this method, the wafer was heated at 350℃ or 450℃. Thus, a multilayer film 1906 was formed.

[0375] Through the above steps, sample 3a was fabricated.

[0376] Next, the oxide semiconductor film 1905 and the multilayer film 190 The sheet resistance of the opening 1917 and the opening 6 was measured in the samples 2a and 3a. A probe is brought into contact with the portion 1919, and the oxide semiconductor film 1905 and the multilayer film 1906 are sealed. The oxide semiconductor film 1905 and the multilayer film 1906 of Sample 2a and Sample 3a were measured for resistance. In 1906, the width W of the conductive film 1907 and the conductive film 1909 facing each other in the top surface shape The distance D was 10 μm. 1907 was set to ground potential, and 1 V was applied to the conductive film 1909. After storing samples 2a and 3a in a 5% atmosphere for 60 and 130 hours, The sheet resistance of each sample was measured.

[0377] The sheet resistance values ​​of Sample 2a and Sample 3a are shown in FIG. 31. In FIG. 31, the solid line indicates The deposition temperature of the silicon nitride film formed as the insulating film 1911 in each sample was 220° C. The dashed line indicates 350°C. The black markers indicate the oxidation temperature of each sample. After the semiconductor film 1905 or the multilayer film 1906 was formed, a heat treatment was performed at 350° C. The white markers indicate the steps of forming the oxide semiconductor film 1905 or the multilayer film 1906, and then The heat treatment was performed at 50° C. The circles indicate that each sample had an oxide semiconductor film 1905. The triangular marker indicates that the sample has a multilayer film 1906. In FIG. 31, the multilayer film 1906 is formed on the sample 3a. The measurement results of sample 3a heated at 350°C after that are plotted as black triangles. not present.

[0378] As shown in FIG. 31, Samples 2a and 3a have low sheet resistance and are suitable for use as electrodes of a capacitance element. It can be seen that the desired sheet resistance is 0.2Ω / sq or less. It can be seen that the time variation of the sheet resistance value is small for Sample 2a and Sample 3a. The oxide semiconductor film or multilayer film in contact with the silicon nitride film is in a high-temperature and high-humidity environment. Since the variation in resistance value is small, it is used as a light-transmitting conductive film for the electrodes of a capacitance element. It is possible.

[0379] Next, for Sample 2a and Sample 3a, the substrate temperatures were set to 25°C, 60°C, and 150°C. The results of measuring the sheet resistance of each are shown in FIG. As for the sample 3a, the deposition temperature of the silicon nitride film formed as the insulating film 1911 was 220 After the oxide semiconductor film 1905 or the multilayer film 1906 is formed, the oxide semiconductor film 1905 or the multilayer film 1906 is heated at 350° C. The black circles indicate the measurement results of sample 2a, and the black triangles indicate the measurement results of sample 2b. The graph shows the measurement results for sample 3a.

[0380] As shown in FIG. 32, even when the measurement temperature is increased, the oxide semiconductor film 1905 and the multilayer film 1906 It can be seen that the gate resistance value does not change. The oxide semiconductor film or the multilayer film in contact with the silicon nitride film can be said to be a degenerate semiconductor. Since the sheet resistance of the transparent film is small even when the temperature changes, it is suitable for use as an electrode for a capacitor. The conductive film may be formed as a conductive film having the above structure.

[0381] The configuration shown in this embodiment may be used in appropriate combination with the configurations shown in other embodiments or embodiments. There can be. EXAMPLES

[0382] In this example, resistance of an oxide semiconductor film will be described with reference to FIGS. In this embodiment, in each step of forming a transistor and a capacitor, The resistance of the membrane was measured.

[0383] Regarding the manufacturing method and structure of a sample having a transistor and a capacitor, ) and FIG. 36. FIG. 36 shows the cross-sectional structure of the capacitance element included in each sample. Shows.

[0384] A gate electrode is formed in a region on a glass substrate 1901 where a transistor is to be formed. Here, a tungsten film with a thickness of 100 nm was formed as the gate electrode.

[0385] Next, a plasma CV film is formed on the glass substrate 1901 and the gate electrode as an insulating film 1903. A silicon nitride film having a thickness of 400 nm was formed by method D.

[0386] Next, on the insulating film 1903, an insulating film 1904 is formed by a plasma CVD method. A silicon oxynitride film having a thickness of nm was formed.

[0387] Next, a metal oxide target (In:Ga:Zn=1:1:1) is deposited on the insulating film 1904. A 35 nm thick IGZO film was then formed by sputtering. The oxide semiconductor film is then subjected to etching treatment using a mask formed by a lithography process. 1905 was formed (Step S1 shown in FIG. 35(A)).

[0388] Next, a thick insulating film 1903 and an oxide semiconductor film 1905 are formed by a sputtering method. A 50 nm thick tungsten film, a 400 nm thick aluminum film, and a 100 nm thick tungsten film were After laminating the titanium films in order, they are etched using a mask formed by a photolithography process. A conductive film 1907 and a conductive film 1909 were formed by performing a dummy patterning process (step S100 in FIG. 35A). P3).

[0389] Through the above steps, Sample 5 was fabricated. A cross-sectional view of the capacitance element included in Sample 5 is shown in FIG. In Sample 5, the oxide film provided in the region where the transistor is to be formed is shown in FIG. The semiconductor film is denoted by C5, and the oxide semiconductor film provided in the region where the capacitor is to be formed is denoted by E5. do.

[0390] After the oxide semiconductor film 1905 is formed, heat treatment is performed at 450° C. for 1 hour in a nitrogen atmosphere. Then, the specimen was heated for 45 min under a nitrogen and oxygen mixed gas atmosphere (nitrogen = 80%, oxygen = 20%). A heat treatment was performed at 0° C. for 1 hour (step S2 in FIG. 35(A)). A conductive film 1909 was formed (Step S3 in FIG. 35A).

[0391] Sample 6 was fabricated by the above steps. A cross-sectional view of the capacitance element included in Sample 6 is shown in FIG. In Sample 6, the oxide semiconductor provided in the region where the transistor is formed is The conductor film is designated as C6, and the oxide semiconductor film provided in the region where the capacitance element is to be formed is designated as E6. .

[0392] After the same process as in Sample 6, the insulating film 1904, the oxide semiconductor film 1905, and the conductive A plastic insulating film, which will later become an insulating film 1910, is formed on the conductive film 1907 and the conductive film 1909. A silicon oxynitride film with a thickness of 450 nm was formed by the plasma CVD method (see FIG. 35(A)). Step S4).

[0393] Next, a mask is formed on the insulating film by a photolithography process, and then etching is performed. A bonding process was performed to form an insulating film 1910 having openings 1913 and 1915 (FIG. 3). Step S8 of 5(A).

[0394] Sample 7 was fabricated by the above steps. A cross-sectional view of the capacitance element included in Sample 7 is shown in FIG. In Sample 7, the oxide semiconductor layer provided in the region where the transistor is to be formed is The conductive film is designated as C7, and the oxide semiconductor film provided in the region where the capacitance element is to be formed is designated as E7. .

[0395] After the same process as in Sample 6, the insulating film 1904, the oxide semiconductor film 1905, and the conductive On the film 1907 and the conductive film 1909, an insulating film that will later become the insulating film 1910, plasma C A silicon oxynitride film with a thickness of 450 nm was formed by the VD method (step 35(A) of FIG. S4).

[0396] Next, a heat treatment was performed for 1 hour in a mixed atmosphere of nitrogen and oxygen at 350° C. (FIG. 35(A) ) step S5).

[0397] Next, an insulating film that will later become an insulating film 1911 was formed on the insulating film 1910. As a result, a silicon nitride film having a thickness of 50 nm was formed by plasma CVD (FIG. 35(A) ) step S7).

[0398] Next, a mask is formed on the insulating film by a photolithography process, and then etching is performed. The insulating film 1910 having the openings 1913 and 1915 and the insulating film 191 1 was formed (Step S8 in FIG. 35(A)).

[0399] Sample 8 was fabricated by the above steps. A cross-sectional view of the capacitance element included in Sample 8 is shown in FIG. In Sample 8, the oxide semiconductor layer provided in the region where the transistor is to be formed is The conductive film is designated as C8, and the oxide semiconductor film provided in the region where the capacitance element is to be formed is designated as E8. .

[0400] In addition, in the case of sample 8, after the heat treatment shown in step S5 of FIG. The insulating film 1910 on the capacitor was etched (step S6 in FIG. 35(A)). In the present invention, the oxide semiconductor film formed in the capacitor is exposed to plasma, Defects, typically oxygen vacancies, were formed in the crystal.

[0401] Next, an insulating film that will later become the insulating film 1911 was formed (Step S7 in FIG. 35(A)). .

[0402] Next, a mask is formed on the insulating film by a photolithography process, and then etching is performed. A bonding process is performed to form an insulating film having openings 1913 and 1915 in the region where the transistor is to be formed. An insulating film 1910 and an insulating film 1911 are formed, and an opening 1917 is formed in a region where a capacitance element is to be formed. , an insulating film 1911 having a film 1919 was formed (Step S8 in FIG. 35(A)).

[0403] Sample 9 was fabricated by the above steps. A cross-sectional view of the capacitance element included in Sample 9 is shown in FIG. In Sample 9, the oxide semiconductor layer provided in the region where the transistor is to be formed is The conductive film is designated as C9, and the oxide semiconductor film provided in the region where the capacitance element is to be formed is designated as E9. .

[0404] In addition, a 100 nm thick indium oxide-oxide film was deposited on a glass substrate by sputtering. Tin oxide compound (ITO-SiO 2 The conductive film was formed using the target The composition of the pellet is In 2 O 3 :SnO 2 :SiO 2 = 85:10:5 [wt %]. Thereafter, a heat treatment was carried out in a nitrogen atmosphere at 250° C. for 1 hour.

[0405] Next, indium oxide-tin oxide compound (ITO-SiO 2 ) on the conductive film of Samples 5 to In a manner similar to Sample 9, a conductive film 1907 and a conductive film 1909 were formed.

[0406] Sample 10 was prepared by the above steps.

[0407] Note that in each of Samples 5 to 10, the conductive film 1907 and the conductive film 19 The opposing width W of 09 was 1 mm and the distance D was 10 μm.

[0408] Next, the oxide semiconductor films provided in the regions in which the transistors of Samples 5 to 9 are formed are C5 to C9 and oxide semiconductors provided in the regions in which the capacitance elements of Samples 5 to 9 are formed. The solid films E5 to E9 and the indium oxide-tin oxide compound (ITO-S) contained in sample 10 iO 2 The sheet resistance of each of the conductive films was measured.

[0409] The measurement results are shown in FIG. The sheet resistance of the semiconductor film E7 is the same as that of the oxide semiconductors C5, E5, and C6 contained in the samples 5 and 6. It can be seen that the difference in the thickness of the oxide semiconductor film formed on the oxide semiconductor film is smaller than that of the oxide semiconductor film formed on the oxide semiconductor film. The oxide semiconductor film is damaged by exposure to plasma during etching of the oxide semiconductor film. It can be seen that the sheet resistance of the oxide semiconductor film is reduced.

[0410] The sheet resistances of the oxide semiconductor films C8 and E8 included in Sample 8 were also tested. Compared with oxide semiconductors C5, E5, C6, E6, C7, and E7 contained in Samples 5 to 7 This is because the amount of the oxide semiconductor film C8 and the amount of the oxide semiconductor film E8 on the oxide semiconductor film C8 are increased. The formed insulating film is made of silicon oxide, and oxygen released by heating is For this reason, the oxide semiconductor film is provided with a layer of By the step of forming an oxide insulating film and the heat treatment step shown in step S5, an oxide semiconductor film The resistance of the oxide semiconductor film in the channel region of a transistor is increased. By using this in the above-mentioned region, a normally-off transistor can be manufactured.

[0411] In addition, the oxide semiconductor film E9 included in the sample 9 has a smaller thickness than the oxide semiconductor film C9. In addition, the oxide semiconductor film C7 and the oxide semiconductor film C8 contained in Sample 7 are It can be seen that the film has a sheet resistance equivalent to that of the compound semiconductor film E7.

[0412] In addition, the oxide semiconductor films C7 and E7 included in Sample 7 and the oxide semiconductor film E7 included in Sample 9 The oxide semiconductor film E9 contained therein is an indium oxide-tin oxide compound ( ITO-SiO 2 ) is one order of magnitude higher in sheet resistance than the conductive film of indium oxide. ITO-Tin Oxide Compound (ITO-SiO 2 ) can be used as an electrode, similar to the conductive film It is possible.

[0413] That is, as in Sample 9, in the region where the transistor is to be formed, the oxide semiconductor By providing an insulating film formed of an oxide insulating film on the film and performing heat treatment, the resistance of the oxide semiconductor film is The concentration of the SiO 2 in the region where the capacitance element is formed is increased, and the region can be used as a channel region. In the present invention, the surface of the oxide semiconductor film is exposed to plasma, and By providing an insulating film formed of a nitride insulating film on the oxide semiconductor film, the resistance of the oxide semiconductor film is reduced, and It can be seen that it can be used as EXAMPLES

[0414] In this example, impurity analysis of an oxide semiconductor film and an insulating film formed over the oxide semiconductor film was performed. This will be explained with reference to FIG.

[0415] In this embodiment, two types of samples (hereinafter referred to as samples) were used for impurity analysis. 11, and sample 12) were prepared.

[0416] First, the method for preparing sample 11 will be described below.

[0417] For sample 11, an IGZO film was formed on a glass substrate, and then a silicon nitride film was formed thereon. After that, heat treatment was performed at 450°C for 1 hour in a nitrogen atmosphere, followed by a mixed gas of nitrogen and oxygen. Heat treatment was performed at 450°C for 1 hour in an atmosphere (nitrogen = 80%, oxygen = 20%).

[0418] The conditions for forming the IGZO film were as follows: sputtering with a metal oxide target (In:Ga:Zn=1:1:1) 2 =100 / 100sccm(O 2 = 50%), pressure = 0.6 Pa, deposition power = 5000 W, substrate temperature = 170 °C. A 100 nm thick IGZO film was deposited.

[0419] The silicon nitride film was formed using the plasma CVD method with SiH 4 / N 2 / NH 3 = 50 / 5000 / 100sccm, pressure = 100Pa, deposition power = 1000W, A silicon nitride film was formed to a thickness of 100 nm under the condition of a substrate temperature of 220°C.

[0420] Next, a method for preparing Sample 12 will be described below.

[0421] An IGZO film is formed on a glass substrate, and then a silicon oxynitride film and a silicon nitride film are formed. After that, a heat treatment was performed at 450°C for 1 hour in a nitrogen atmosphere, and then a nitrogen Heat treatment at 450℃ for 1 hour in a nitrogen and oxygen mixed gas atmosphere (nitrogen = 80%, oxygen = 20%) The theory was carried out.

[0422] The deposition conditions for the IGZO film and the silicon nitride film were the same as those for sample 11. The deposition conditions for the silicon oxynitride film were the plasma CVD method. SiH 4 / N 2 O = 30 / 4000sccm, pressure = 40Pa, deposition power = 150W A silicon oxynitride film having a thickness of 50 nm is formed under the condition of a substrate temperature of 220° C., and then, Using the plasma CVD method, SiH 4 / N 2 O = 160 / 4000sccm, Pressure = 200P a, A 400 nm thick oxynitride film was formed under the conditions of deposition power = 1500 W and substrate temperature = 220 °C. A silicon film was formed.

[0423] The impurity analysis results of Samples 11 and 12 are shown in FIG.

[0424] The impurity analysis was carried out using secondary ion mass spectrometry (SIMS). Using Ion Mass Spectrometry, the sample was separated from the direction of the arrow shown in Figure 28. That is, the measurements were taken from the glass substrate side.

[0425] FIG. 28(A) shows the hydrogen (H) concentration profile obtained by measuring sample 11. FIG. 28(B) shows the hydrogen (H) concentration profile obtained by measuring sample 12. It is.

[0426] From Figure 28(A), the hydrogen (H) concentration in the IGZO film is 1.0×10 20 atoms / c m 3 It can be seen that the hydrogen (H) concentration in the silicon nitride film is 1.0×10 2 3 atoms / cm 3 In addition, from FIG. 28(B), the hydrogen in the IGZO film (H) Concentration is 5.0×10 19atoms / cm 3 It can be seen that nitric oxide The hydrogen (H) concentration in the silicon oxide film is 3.0×10 21 atoms / cm 3 To be I understand.

[0427] Due to its measurement principle, SIMS analysis cannot measure the area near the sample surface or the layered boundary between films of different materials. It is known that it is difficult to obtain accurate data near the surface. When analyzing the distribution of hydrogen (H) in the thickness direction by SIMS, the area in which the target film exists is In the range, there is no extreme fluctuation, and the average value in the region where almost constant intensity is obtained is adopted. do.

[0428] In this way, by changing the composition of the insulating film in contact with the IGZO film, the water in the IGZO film Differences were confirmed in the element (H) concentration.

[0429] For example, when the above-mentioned IGZO film is used in the channel formation region of a transistor, Sample 1 As shown in FIG. 2, a silicon oxynitride film is preferably provided in contact with the IGZO film. As a light-transmitting conductive film used for the electrodes of the capacitor element, IGZO is used as shown in Sample 11. It is preferable to provide a silicon nitride film in contact with the film. The IGZO film used for the channel formation region of the transistor and the I The hydrogen concentration in the IGZO film can be changed even when the GZO film and the IGZO film are fabricated using the same process. EXAMPLES

[0430] In this example, the amount of defects in the oxide semiconductor film and the multilayer film was measured using FIGS. He explains.

[0431] First, the structure of the sample will be described.

[0432] Sample 13 is a 35 nm-thick oxide semiconductor film formed on a quartz substrate and an oxide semiconductor A nitride insulating film having a thickness of 100 nm is formed on the film.

[0433] Samples 14 and 15 are a 30 nm thick multilayer film formed on a quartz substrate and a 30 nm thick multilayer film. The multilayer film of Sample 14 has a thickness of A first IGZO film having a thickness of 10 nm, a second IGZO film having a thickness of 10 nm, and a third IGZO film having a thickness of 10 nm The sample 15 has a first IGZO film with a thickness of 20 nm. The O film, the second IGZO film with a thickness of 15 nm, and the third IGZO film with a thickness of 10 nm were stacked in this order. In comparison with Sample 13, Samples 14 and 15 each have a structure in which a semiconductor layer is formed instead of an oxide semiconductor film. The difference is that it has a multilayer film.

[0434] Sample 16 is a 100 nm-thick oxide semiconductor film formed on a quartz substrate and an oxide semiconductor A 250 nm thick oxide insulating film was formed on the solid film, and a 10 nm thick oxide insulating film was formed on the solid film. The sample 16 has a nitride insulating film with a thickness of 0 nm. The difference is that the conductor film is not in contact with the nitride insulating film but is in contact with the oxide insulating film.

[0435] Next, the method for preparing each sample will be described.

[0436] First, a method for preparing the sample 13 will be described.

[0437] A 35 nm thick IGZO film was formed on a quartz substrate as an oxide semiconductor film. The film was formed by sputtering using a metal oxide target (In:Ga:Z n = 1:1:1) and Ar / O 2 =100sccm / 100sccm(O 2 =50% ), pressure = 0.6 Pa, film formation power = 5000 W, and substrate temperature = 170°C.

[0438] Next, as the first heat treatment, a heat treatment was performed in a nitrogen atmosphere at 450° C. for 1 hour, and then Heating for 1 hour in a nitrogen and oxygen mixed gas atmosphere (nitrogen = 80%, oxygen = 20%) at 450℃ Processing was carried out.

[0439] Next, a silicon nitride film having a thickness of 100 nm is formed as a nitride insulating film on the oxide semiconductor film. The conditions for forming the silicon nitride film were as follows: plasma CVD method, SiH 4 / N 2 / N H 3 = 50 / 5000 / 100sccm, pressure = 100Pa, deposition power = 1000W, The plate temperature was 350°C.

[0440] Next, as a second heat treatment, heat treatment was performed at 250° C. in a nitrogen atmosphere for 1 hour.

[0441] Sample 13 was prepared by the above steps.

[0442] Next, a method for preparing the sample 14 will be described.

[0443] In Sample 14, a multilayer film was formed instead of the oxide semiconductor film in Sample 13. A metal oxide target (In:Ga:Zn= 1:3:2) and Ar / O 2 =180 / 20sccm(O 2 = 10%), Pressure = 0. The first IGZ was formed with a thickness of 10 nm under the conditions of 6 Pa, deposition power = 5000 W, and substrate temperature = 25 °C. Next, a metal oxide target (In:Ga:Zn =1:1:1) and Ar / O 2 =100 / 100sccm(O 2 = 50%), pressure = The second layer was deposited to a thickness of 10 nm under the conditions of 0.6 Pa, deposition power of 5000 W, and substrate temperature of 170°C. Next, a metal oxide target (In:Ga Zn=1:3:2) and Ar / O 2 =180 / 20sccm(O 2 = 10%), pressure The third layer was deposited to a thickness of 10 nm under the conditions of pressure = 0.6 Pa, deposition power = 5000 W, and substrate temperature = 25 °C. An IGZO film was formed.

[0444] The other steps were the same as those of Sample 13. Sample 14 was formed by the above steps.

[0445] Next, a method for preparing Sample 15 will be described.

[0446] In Sample 15, a multilayer film was formed instead of the oxide semiconductor film in Sample 13. The first IGZO film was deposited on a quartz substrate under the same conditions as the first IGZO film shown in Sample 14. Next, the second IGZO film shown in Sample 14 was formed by sputtering. A second IGZO film was deposited to a thickness of 15 nm using the same conditions as for the ZO film. A third IGZO film with a thickness of 10 nm was formed using the same conditions as the third IGZO film shown in FIG. Ta.

[0447] The other steps were the same as those of Sample 13. Sample 15 was formed by the above steps.

[0448] Next, a method for preparing the sample 16 will be described.

[0449] Sample 16 was prepared by growing a 100 nm thick oxide semiconductor film on a quartz substrate under the same conditions as sample 13. A film was formed.

[0450] Next, a first heat treatment was carried out under the same conditions as those for Sample 13.

[0451] Next, a first silicon oxynitride film having a thickness of 50 nm was formed as an oxide insulating film over the oxide semiconductor film. A silicon oxide film and a second silicon oxynitride film having a thickness of 200 nm were formed. By VD method, SiH 4 / N 2 O = 30 / 4000sccm, pressure = 40Pa, deposition power = A first silicon oxynitride film having a thickness of 50 nm was formed under the conditions of 150 W and substrate temperature of 220°C. Then, the SiH 4 / N 2 O = 160 / 4000sccm, Pressure = 200 Pa, deposition power = 1500 W, substrate temperature = 220 °C, thickness of 200 nm The second silicon oxynitride film was formed having a thickness of 100 nm. The film contains more oxygen than meets the theoretical requirement.

[0452] Next, using the same conditions as for Sample 13, a silicon nitride film with a thickness of 100 nm was formed on the oxide insulating film. was formed.

[0453] Next, a second heat treatment was carried out using the same conditions as for Sample 13.

[0454] Through the above steps, sample 16 was formed.

[0455] Next, ESR measurements were performed on Samples 13 to 16. The ESR measurements were performed at a predetermined temperature. The magnetic field value at which microwave absorption occurs (H 0 ) from the equation g=hν / βH 0 , using g Here, ν is the frequency of the microwave. h is the Planck constant. and β is the Bohr magneton, both constants.

[0456] Here, the ESR measurements were performed under the following conditions: The measurement temperature was room temperature (25°C), and the The 2GHz radio frequency power (microwave power) was set to 20mW, and the magnetic field direction was set to the same as that of the sample. The film surface was parallel to the

[0457] The oxide semiconductor films and multilayer films included in Samples 13 to 15 were subjected to ESR measurement. The first derivative curves are shown in FIG. 29. FIG. 29(A) shows the measurement results for Sample 13, and FIG. 29(B) shows the measurement results for Sample 13. 29(C) shows the measurement results for sample 15.

[0458] The first differential curve obtained by ESR measurement of the oxide semiconductor film included in sample 16 is shown in Figure 30. show.

[0459] In FIG. 29(A) to FIG. 29(C), sample 13 was oxidized at a g value of 1.93. A signal having a symmetry due to defects in the semiconductor film is detected. In Fig. 15, a signal with symmetry due to defects in the multilayer film is detected at a g value of 1.95. The spin density at g-value 1.93 in sample 13 is 2.5×10 19 spi ns / cm 3 is the sum of the spin densities for the g values ​​of 1.93 and 1.95 in sample 14. is 1.6 x 10 19 spins / cm 3 The g value in sample 15 is 1.93 and The sum of the spin densities of 1.95 is 2.3 × 10 19 spins / cm 3 That is, It can be seen that the oxide semiconductor film and the multilayer film contain defects. An example of a defect in a multilayer film is an oxygen vacancy.

[0460] In FIG. 30, Sample 16 has a smaller thickness of the oxide semiconductor film than Samples 13 to 15. Even though the thickness is thick, no symmetrical signal due to the defect is detected, i.e., the defect is underdetected. Below the detection limit (here, the detection limit is 3.7 × 10 16 spins / cm 3 (Let us suppose that This shows that the amount of defects contained in the oxide semiconductor film cannot be detected.

[0461] A nitride insulating film, here a nitride insulating film formed by plasma CVD, is applied to an oxide semiconductor film or a multilayer film. When the silicon film comes into contact with the oxide semiconductor film or multilayer film, defects, typically oxygen vacancies, are formed. On the other hand, when an oxide insulating film, a silicon oxynitride film, is formed on an oxide semiconductor film, When the silicon oxynitride film is provided with the oxygen stoichiometric composition, the excess oxygen contained in the silicon oxynitride film is Therefore, more oxygen diffuses into the oxide semiconductor film than in the case of the oxide semiconductor film, and defects in the oxide semiconductor film are not increased.

[0462] From the above, as shown in Samples 13 to 15, the oxide semiconductor in contact with the nitride insulating film The thin film or multilayer film has many defects, typically oxygen vacancies, and is highly conductive, so the current of the capacitor element is On the other hand, as shown in sample 16, the oxide film in contact with the oxide insulating film The semiconductor film or multilayer film has a small amount of oxygen vacancies and is therefore less conductive, so the channel area of ​​the transistor is It can be used as a hole formation region.

[0463] Here, the reason why the resistivity of the oxide semiconductor film and the multilayer film in contact with the nitride insulating film decreases is as follows. The following describes each of these.

[0464] <Energy and Stability among Existence Forms of H> First, the calculated results regarding the energy and stability of the forms of H present in the oxide semiconductor film will be explained. Here, InGaZnO is used as the oxide semiconductor film. was used. 4

[0465] The structure used in the calculation was based on an 84 - atom bulk model obtained by doubling the hexagonal unit cell of InGaZnO 4 in the a - axis and b - axis directions by a factor of 2 each.

[0466] In the bulk model, a model was prepared in which one O atom bonded to three In atoms and one Zn atom was replaced by an H atom (see Fig. 33(A)). Also, in Fig. 33(A), the view of the ab - plane in the InO layer from the c - axis is shown in Fig. 33(B). The region where one O atom bonded to three In atoms and one Zn atom was removed was denoted as an oxygen vacancy Vo and is shown by a dashed line in Fig. 33( A) and Fig. 33(B). Also, an H atom located in the oxygen vacancy Vo is denoted as V oH.

[0467] Also, in the bulk model, one O atom bonded to three In atoms and one Zn atom was removed to form an oxygen vacancy (Vo). Near the Vo, a model was prepared in which an H atom was bonded to the O atom bonded to one Ga atom and two Zn atoms with respect to the ab - plane (see Fig. 33 (C)). Also, in Fig. 33(C), the view of the ab - plane in the InO layer from the c - axis is shown in Fig. 33(D). In Fig. 33(C) and Fig. 33(D), the oxygen vacancy Vo is shown by a dashed line . Also, a model having an oxygen vacancy Vo and, near the oxygen vacancy Vo, an H atom bonded to the O atom bonded to one Ga atom and two Zn atoms with respect to the ab - plane is denoted as Vo + H ​​​​​ Denote it.

[0468] For the above two models, an optimization calculation was performed with the lattice constant fixed, and the total energy was calculated. Note that the smaller the value of the total energy, the more stable the structure can be said to be.

[0469] For the calculation, the first-principles calculation software VASP (The Vienna Ab initio tio simulation package) was used. The calculation conditions are shown in Table 1.

[0470]

Table 1

[0471] Also, the total energies of the two models calculated by the calculation are shown in Table 2.

[0472]

Table 2

[0473] From Table 2, the total energy of VoH is 0.78 eV smaller than that of Vo + H. Therefore, it can be said that VoH is more stable than Vo + H. Therefore, when an H atom approaches an oxygen vacancy (Vo), the H atom is more likely to be incorporated into the oxygen vacancy (Vo) rather than bonding to an O atom. it can be considered that it is easier to be incorporated into the oxygen vacancy (Vo) rather than bonding to an O atom. it is considered.

[0474] <Thermodynamic state of VoH> Next, the formation energy and charge state of VoH, in which an H atom is incorporated into an oxygen vacancy (Vo), The calculation results are explained below. The formation energy of VoH varies depending on the charge state. , and also depends on the Fermi energy. Therefore, VoH depends on the Fermi energy and is stable. The charge state is different. Here, the state where VoH releases one electron is called (VoH) + Shown The state in which one electron is captured is called (VoH) - The state without electron movement is represented as (VoH ) 0 (VoH) + , (VoH) - , (VoH) 0 Calculate the formation energy of each I calculated it.

[0475] The calculation conditions are shown in Table 3.

[0476] [Table 3] The electronic state pseudopotential is the Projector Augmented Wave (P The potential generated by the Heyd-Scuseria-E The rnzerhof (HSE) DFT hybrid functional (HSE06) was used.

[0477] In addition, the formation energy of oxygen defects is calculated assuming a dilute limit of oxygen defect concentration. The energies were calculated by correcting for the excess broadening of the electrons and holes into the conduction band and valence band. The upper end of the valence band of a perfect crystal is taken as the energy origin, and the shift in the valence band due to defect structures is Corrections were made using the average electrostatic potential.

[0478] In Figure 34(A), (VoH) +, (VoH) - , (VoH) 0 The respective formation energies The horizontal axis is the Fermi level, and the vertical axis is the formation energy. The solid line indicates the ) + The dashed line shows the formation energy of (VoH) 0 The dashed line indicates the formation energy of (VoH) - The formation energy of VoH is shown. Also, the charge of VoH changes from + to 0 to -. The transition level is denoted as ε(+ / -).

[0479] Figure 34(B) shows the thermodynamic transition level of VoH. From the calculation results, InGaZnO 4 The energy gap of the valence band is 2.739 eV. V, the transition level (ε(+ / -)) is 2.62 eV, which is located just below the conduction band. This shows that the incorporation of H atoms into the oxygen vacancies (Vo) results in the formation of InGaZ nO 4 It can be seen that it becomes n-type.

[0480] When the oxide semiconductor film is exposed to plasma, the oxide semiconductor film is damaged, and the oxide semiconductor In the conductive film, defects, typically oxygen vacancies, are generated. When the oxide semiconductor film comes into contact with the nitride insulating film, hydrogen contained in the nitride insulating film moves to the oxide semiconductor film. Hydrogen enters the oxygen vacancies in the oxide semiconductor film, forming VoH in the oxide semiconductor film. As a result, the oxide semiconductor film becomes n-type and the resistivity decreases. The oxide semiconductor film in contact with the first electrode can be used as an electrode of a capacitor. EXAMPLES

[0481] In this example, the transmittance of an oxide semiconductor film in contact with a nitride insulating film was measured using FIG. explain.

[0482] The structure of the sample will now be described.

[0483] Sample 17 is a glass substrate on which an oxide semiconductor film having a thickness of 35 nm is formed. A silicon nitride film having a thickness of 100 nm is formed on the film.

[0484] Sample 18 is a glass substrate on which an oxide semiconductor film having a thickness of 35 nm is formed. A silicon nitride film having a thickness of 100 nm is formed on the film, and a silicon nitride film having a thickness of 100 nm is formed on the silicon nitride film. m Indium oxide-tin oxide compound (ITO-SiO 2 ) membrane is formed.

[0485] Note that in Samples 17 and 18, the oxide semiconductor films each have an atomic ratio of metal elements of The In-Ga-Zn oxide (IGZO(111)) has a structure of In:Ga:Zn=1:1:1. An In-Ga-Zn oxide film was formed by sputtering using a ZnO target.

[0486] In Samples 17 and 18, the silicon nitride film was prepared by using silane, ammonia, and nitrogen. The film was formed by plasma CVD using nitrogen.

[0487] In sample 18, an indium oxide-tin oxide compound (ITO-SiO 2 ) The film is The film was formed by the talc method.

[0488] Sample 19 was a 100 nm thick indium oxide-tin oxide (ITO) compound film on a glass substrate. O-SiO 2 ) film is formed. 2 ) The film was formed by sputtering.

[0489] Next, the visible light transmittance was measured for Samples 17 to 19. The results are shown in Figure 37. Figure 37(A) shows the measurement results for sample 17, and Figure 37(B) shows the measurement results for sample 18. FIG. 37(C) shows the measurement results for Sample 19.

[0490] As shown in FIG. 37(A), in sample 17, when the wavelength is 340 nm or more and 800 nm or less, The transmittance is 60% or more, and the transmittance at wavelengths of 380 nm to 800 nm is 70% or more. % or more, and the transmittance at wavelengths of 430 nm to 800 nm is 80% or more. .

[0491] As shown in FIG. 37B, in sample 18, when the wavelength is 380 nm or more and 800 nm or less, The transmittance is 60% or more, and the transmittance at wavelengths of 430 nm to 800 nm is 70% or more. % or more.

[0492] As shown in FIG. 37A, the oxide semiconductor film in contact with the silicon nitride film is The ITO-SiO 2 It has a transmittance equal to or higher than that of the membrane. ) oxide semiconductor film, silicon nitride film, and ITO-SiO 2 The film is laminated In the structure, the ITO-SiO 2 It has the same transmittance as the membrane. Therefore, the oxide semiconductor film, silicon nitride film, and ITO-SiO 2 A container with a laminated film It can be seen that the quantum element has light-transmitting properties. The nitride insulating film is formed on the ITO-SiO 2 Instead of the film, a light-transmitting conductive film is formed. Even if the insulating film is removed, a light-transmitting capacitor element can be manufactured.

Claims

1. A display device having a pixel including a transistor and a pixel electrode, a first conductive film having a region disposed above an insulating surface and functioning as a gate of the transistor; a second conductive film having a region disposed above the insulating surface; a first insulating film having a region disposed above the first conductive film and a region disposed above the second conductive film; a first metal oxide film having a region disposed above the first insulating film and having a channel formation region of the transistor; a second metal oxide film having a region disposed above the first insulating film; a third conductive film having a region disposed above the first metal oxide film and functioning as one of a source and a drain of the transistor; a fourth conductive film having a region disposed above the first metal oxide film and functioning as the other of the source and the drain of the transistor; a fifth conductive film having a region disposed above the second metal oxide film and having a function of electrically connecting the second metal oxide film and the second conductive film; a second insulating film having a region disposed above the first metal oxide film and a region disposed above the second metal oxide film; a third insulating film having a region disposed above the second insulating film; the pixel electrode having a region disposed above the third insulating film and electrically connected to the fourth conductive film; having the pixel electrode has a region overlapping the second metal oxide film without the second insulating film and through the third insulating film; Display device.

2. A display device having a pixel including a transistor and a pixel electrode, a first conductive film having a region disposed above an insulating surface and functioning as a gate of the transistor; a second conductive film having a region disposed above the insulating surface; a first insulating film having a region disposed above the first conductive film and a region disposed above the second conductive film; a first metal oxide film having a region disposed above the first insulating film and having a channel formation region of the transistor; a second metal oxide film having a region disposed above the first insulating film; a third conductive film having a region disposed above the first metal oxide film and functioning as one of a source and a drain of the transistor; a fourth conductive film having a region disposed above the first metal oxide film and functioning as the other of the source and the drain of the transistor; a fifth conductive film having a region disposed above the second metal oxide film and having a function of electrically connecting the second metal oxide film and the second conductive film; a second insulating film having a region disposed above the first metal oxide film and a region disposed above the second metal oxide film; a third insulating film having a region disposed above the second insulating film; the pixel electrode having a region disposed above the third insulating film and electrically connected to the fourth conductive film; having the second insulating film and the third insulating film have regions overlapping with a channel formation region of the transistor, the pixel electrode has a region overlapping the second metal oxide film without the second insulating film and through the third insulating film; Display device.

3. A display device having a pixel including a transistor and a pixel electrode, a first conductive film having a region disposed above an insulating surface and functioning as a gate of the transistor; a second conductive film having a region disposed above the insulating surface; a first insulating film having a region disposed above the first conductive film and a region disposed above the second conductive film; a first metal oxide film having a region disposed above the first insulating film and having a channel formation region of the transistor; a second metal oxide film having a region disposed above the first insulating film; a third conductive film having a region disposed above the first metal oxide film and functioning as one of a source and a drain of the transistor; a fourth conductive film having a region disposed above the first metal oxide film and functioning as the other of the source and the drain of the transistor; a fifth conductive film having a region disposed above the second metal oxide film and having a function of electrically connecting the second metal oxide film and the second conductive film; a second insulating film having a region disposed above the first metal oxide film and a region disposed above the second metal oxide film; a third insulating film having a region disposed above the second insulating film; the pixel electrode having a region disposed above the third insulating film and electrically connected to the fourth conductive film; having The pixel electrode has a function as one electrode of an organic EL element, the pixel electrode has a region overlapping the second metal oxide film without the second insulating film and through the third insulating film; Display device.

4. A display device having a pixel including a transistor and a pixel electrode, a first conductive film having a region disposed above an insulating surface and functioning as a gate of the transistor; a second conductive film having a region disposed above the insulating surface; a first insulating film having a region disposed above the first conductive film and a region disposed above the second conductive film; a first metal oxide film having a region disposed above the first insulating film and having a channel formation region of the transistor; a second metal oxide film having a region disposed above the first insulating film; a third conductive film having a region disposed above the first metal oxide film and functioning as one of a source and a drain of the transistor; a fourth conductive film having a region disposed above the first metal oxide film and functioning as the other of the source and the drain of the transistor; a fifth conductive film having a region disposed above the second metal oxide film and having a function of electrically connecting the second metal oxide film and the second conductive film; a second insulating film having a region disposed above the first metal oxide film and a region disposed above the second metal oxide film; a third insulating film having a region disposed above the second insulating film; the pixel electrode having a region disposed above the third insulating film and electrically connected to the fourth conductive film; having the second insulating film and the third insulating film have regions overlapping with a channel formation region of the transistor, The pixel electrode has a function as one electrode of an organic EL element, the pixel electrode has a region overlapping the second metal oxide film without the second insulating film and through the third insulating film; Display device.

5. In any one of claims 1 to 4, the second metal oxide film functions as one electrode of a capacitor; The pixel electrode functions as the other electrode of the capacitance element. Display device.

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