Display device

Abstract

To provide a semiconductor device including a capacitor element with larger charge capacity without reducing an opening ratio.SOLUTION: A capacitor element includes a transistor including a semiconductor film with a light-transmitting property, and a dielectric film provided between a pair of electrodes. The pair of electrodes and the dielectric film are formed of a material with a light-transmitting property. One of the pair of electrodes uses a semiconductor film formed on the same surface as the semiconductor film of the transistor. As the dielectric film forming the capacitor element, a gate insulating film is used. The other of the pair of electrodes is formed using a semiconductor film with a light-transmitting property or a conductive film with a light-transmitting property.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] In this specification, a semiconductor device is a device that can function by utilizing semiconductor characteristics. Refers to transistors, semiconductor circuits, memory devices, imaging devices, display devices, and electro-optical devices All electronic devices and other devices can be considered semiconductor devices. [Background technology]

[0003] In recent years, flat panel displays such as liquid crystal displays (LCDs) have become widely used. 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 a and a capacitance element connected in parallel to the liquid crystal element. .

[0004] The semiconductor material constituting the semiconductor film of the transistor is amorphous (non-crystalline) silicon. Silicon semiconductors such as silicon or polysilicon are widely used.

[0005] In addition, metal oxides that exhibit semiconductor properties (hereinafter referred to as oxide semiconductors) are used in transistors. It is a semiconductor material that can be used for semiconductor films. For example, zinc oxide or In-Ga-Zn-based oxide Techniques for fabricating transistors using nitride semiconductors have been disclosed (Patent Document 1 and Patent Document 2). (See patent document 2). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-123861 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-96055 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 the pair of electrodes. One electrode is a gate electrode, a source electrode, a drain electrode, or the like that constitutes a transistor. In many cases, the light-shielding layer is formed of a conductive film having a light-shielding property.

[0008] In addition, the larger the capacitance value of the capacitance element, the more the liquid crystal of the liquid crystal element will change when an electric field is applied. The period during which the molecular orientation can be kept constant can be extended. In a display device, being able to extend this period reduces the number of times image data is rewritten. This makes it possible to reduce power consumption.

[0009] In order to increase the charge capacity of the capacitance element, the area occupied by the capacitance element is increased. However, there is a way to increase the area where the pair of electrodes overlap. In a display device, a conductive film having a light-shielding property is used to increase the area where a pair of electrodes overlap. If the area of ​​the film is increased, the aperture ratio of the pixel decreases, and the display quality of the image deteriorates.

[0010] In view of the above, one aspect of the present invention is to provide a liquid crystal display device having a high aperture ratio and an increased charge capacity. An object of the present invention is to provide a semiconductor device including a capacitor that can be used for a semiconductor device. [Means for solving the problem]

[0011] One embodiment of the present invention is a semiconductor device including a transistor and a light-transmitting capacitor. Specifically, the pair of electrodes and the dielectric film constituting the capacitor element are formed by a light-transmitting At least one of the pair of electrodes is formed from a light-transmitting semiconductor film. The other of the pair of electrodes constituting the capacitor is formed of a light-transmitting conductive film. Alternatively, the light-transmitting semiconductor film is used.

[0012] The light-transmitting semiconductor film can be formed using an oxide semiconductor. has a large energy gap of 3.0 eV or more and a high transmittance for visible light. is.

[0013] A light-transmitting capacitor element can be manufactured by using a material and a manufacturing process for a transistor. For example, one electrode of the capacitor element can be formed by a process of forming a semiconductor film of a transistor. The dielectric film of the capacitor element can be formed by using the process for forming the gate insulating film of the transistor. can.

[0014] A part of the semiconductor film formed in the process of forming the semiconductor film of the transistor is used as an electrode of the capacitor element. When the semiconductor film is to function as a semiconductor, it is preferable to increase the conductivity of the semiconductor film. , nitrogen, fluorine, aluminum, phosphorus, arsenic, indium, tin, antimony and rare gases It is preferable to add one or more elements selected from the above to the semiconductor film. The method of adding to the semiconductor film includes ion implantation and ion doping. The above element can also be added by exposing the semiconductor film to plasma containing the above element.

[0015] In addition, when the oxide semiconductor film is used as an electrode of a capacitor, A nitride insulating film may be provided. When the nitride insulating film and the oxide semiconductor film are in contact with each other, the nitride insulating film Defect levels (interface levels) at the interface between the nitride insulating film and the oxide semiconductor film, or The nitrogen contained in the oxide semiconductor film diffuses into the oxide semiconductor film, thereby increasing the electrical conductivity of the oxide semiconductor film. increases.

[0016] From the above, in the capacitor element, by adopting a structure in which the nitride insulating film is in contact with the semiconductor film, An element that increases the conductivity is added to the semiconductor film by ion implantation or ion doping. This allows the omission of additional processes, improves the yield of semiconductor devices, and reduces manufacturing costs. It is possible.

[0017] When the semiconductor film is used as an electrode of a capacitance element, the conductivity of the semiconductor film is 10 S / cm or more. The viscosity is set to 1000 S / cm or less, preferably 100 S / cm or more and 1000 S / cm or less.

[0018] With the above structure, the capacitor element has light-transmitting properties, and therefore, a transistor in a pixel is formed. Therefore, the aperture ratio can be increased. As a result, a semiconductor device having an increased charge capacity can be obtained. A semiconductor device having such a structure can be obtained.

[0019] In addition, in the capacitance element, the dielectric film is an insulating film that constitutes a transistor. For example, the insulating film may have the same stack structure as the insulating film. When the insulating film is a laminated structure of an insulating nitride film and an insulating oxide film, the dielectric of the capacitor element The film can have a stacked structure of an insulating nitride film and an insulating oxide film.

[0020] Note that the semiconductor film of the transistor is an oxide semiconductor film, and the nitride insulating film and the oxide insulating film are stacked. When the structure is an insulating film provided over a gate electrode, the oxide insulating film is not permeable to nitrogen. It is preferable that the material has a barrier property against nitrogen.

[0021] By doing so, nitrogen and hydrogen are introduced into the oxide semiconductor film, which is the semiconductor film of the transistor. Diffusion of one or both of these can be suppressed, thereby suppressing fluctuations in the electrical characteristics of the transistor. can be done.

[0022] In the above-described semiconductor device according to one embodiment of the present invention, the gate electrode of the transistor is electrically connected to the a scanning line connected to the scanning line, and a capacitor extending in a direction parallel to the scanning line and provided on the same surface as the scanning line; One electrode of the capacitance element is connected to the source electrode or drain electrode of the transistor. The conductive film that can be formed when forming the drain electrode electrically connects the transistor is connected.

[0023] The other electrode of the capacitor is electrically connected to the capacitor line. The capacitor line can be provided so that a part of the capacitor line contacts the outer periphery of the electrode. By doing so, the contact resistance between the electrode and the capacitance line can be reduced, and charges can be efficiently transferred to the capacitance element. can be supplied.

[0024] One embodiment of the present invention is a transistor including a light-transmitting semiconductor film in a channel formation region; A capacitor element is provided with a dielectric film between a first electrode and a second electrode, and The first electrode, the second electrode, and the dielectric film are made of a light-transmitting material. The semiconductor film formed on the same surface as the light-transmitting semiconductor film of the photoresist functions as the first electrode. The second electrode is formed below the gate insulating film of the transistor, and the second electrode is formed below the gate insulating film of the transistor. A semiconductor device characterized in that the region where the first electrode and the second electrode overlap is used as a dielectric film. It is a conductor device.

[0025] One embodiment of the present invention is a transistor including a light-transmitting semiconductor film in a channel formation region; A capacitor element is provided with a dielectric film between a first electrode and a second electrode, and The first electrode, the second electrode, and the dielectric film are made of a light-transmitting material. The semiconductor film formed on the same surface as the light-transmitting semiconductor film of the transistor is used as the first electrode. The dielectric film has a laminated structure of a nitride insulating film and an oxide insulating film, and the second electrode is a nitride insulating film. The semiconductor device is characterized in that it is formed in contact with an insulating film.

[0026] The first electrode has a higher conductivity than a channel formation region of the light-transmitting semiconductor film of the transistor. The first electrode is electrically connected to the pixel electrode, and the potential of the second electrode is The potential is higher than the potential of the pixel electrode.

[0027] Note that a manufacturing method of a semiconductor device according to one embodiment of the present invention is also an embodiment of the present invention. Included. [Effects of the Invention]

[0028] 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. An apparatus can be provided. [Brief explanation of the drawings]

[0029] [Figure 1]1A and 1B are a diagram illustrating a semiconductor device according to one embodiment of the present invention and a circuit diagram illustrating a pixel. [Figure 2] 1A and 1B are top views illustrating a semiconductor device according to one embodiment of the present invention. [Figure 3] 1A and 1B are cross-sectional views illustrating a semiconductor device according to one embodiment of the present invention. [Figure 4] 1A to 1C are cross-sectional views illustrating a method for manufacturing a semiconductor device according to one embodiment of the present invention. [Figure 5] 1A to 1C are cross-sectional views illustrating a method for manufacturing a semiconductor device according to one embodiment of the present invention. [Figure 6] 1A and 1B are top views illustrating a semiconductor device according to one embodiment of the present invention. [Figure 7] 1A and 1B are top views illustrating a semiconductor device according to one embodiment of the present invention. [Figure 8] 1A and 1B are cross-sectional views illustrating a semiconductor device according to one embodiment of the present invention. [Figure 9] 1A and 1B are cross-sectional views illustrating a semiconductor device according to one embodiment of the present invention. [Figure 10] 1A and 1B are top views illustrating a semiconductor device according to one embodiment of the present invention. [Figure 11] 1A and 1B are cross-sectional views illustrating a semiconductor device according to one embodiment of the present invention. [Figure 12] 1A and 1B are cross-sectional views illustrating a semiconductor device according to one embodiment of the present invention. [Figure 13] 1A and 1B are top views illustrating a semiconductor device according to one embodiment of the present invention. [Figure 14] 1A and 1B are cross-sectional views illustrating a semiconductor device according to one embodiment of the present invention. [Figure 15] 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 16] 1A to 1C illustrate electronic devices using a semiconductor device which is one embodiment of the present invention. [Figure 17] 1A to 1C illustrate electronic devices using a semiconductor device which is one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0030] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to the following description, and various modifications in form and details are possible by those skilled in the art. Furthermore, the present invention should not be construed as being limited to the description of the following embodiments. It is not something that can be done.

[0031] In the configuration of the present invention described below, the same parts or parts having similar functions are designated as identical. The same reference numerals are used in common among different drawings, and repeated explanations thereof will be omitted. When referring to a part that has a function, the hatch pattern is the same and no particular symbol is attached. be.

[0032] In each figure described herein, the size of each structure, film thickness, or area is shown for clarity. The figures may be exaggerated for illustrative purposes only and are not necessarily limited to that scale.

[0033] In this specification and elsewhere, ordinal numbers such as 1st, 2nd, etc. are used for convenience, It does not indicate the order of processes or stacking layers. It does not indicate a specific name for the matter.

[0034] In addition, the function of the "source" and "drain" in the present invention is to control the direction of current in the circuit operation. For this reason, in this specification, the term "software" is used. The terms "source" and "drain" may be used interchangeably.

[0035] Voltage refers to the potential difference between two points, and potential refers to the electrostatic field at a certain point. It refers to the electrostatic energy (electrical potential energy) of a unit charge in a particle. Generally, the potential difference between the potential at a certain point and a reference potential (for example, ground potential) is This is simply called potential or voltage, and potential and voltage are often used synonymously. Therefore, in this specification, unless otherwise specified, the term "potential" may be read as "voltage" or Voltage may be read as potential.

[0036] In this specification, "parallel" means that two straight lines are arranged at an angle of -10° or more and 10° or less. Therefore, it includes the case where the angle is between -5° and 5°. refers to the state in which two straight lines are arranged at an angle of 80° or more and 100° or less. This includes cases where the angle is between 85° and 95°.

[0037] (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 semiconductor device according to one embodiment of the present invention will be described using a liquid crystal display device as an example. Reveal.

[0038] <Configuration of Semiconductor Device> FIG. 1A shows a structural example of a semiconductor device. The element portion 100, the scanning line driving circuit 104, and the signal line driving circuit 106 are arranged parallel to each other or approximately parallel to each other. The m scanning lines 10 are arranged in parallel and the potentials of which are controlled by a scanning line driving circuit 104. 7 are arranged parallel or approximately parallel to each other, and the potential is controlled by a signal line driving circuit 106. The pixel section 100 has n signal lines 109 that are controlled by the signal lines 109. The pixel array 101 has a plurality of pixels 101 arranged parallel or approximately parallel to each other along a scanning line 107. The pixel has capacitance lines 115 (not shown in FIG. 1A) arranged in rows. may be arranged parallel or approximately parallel to each other along the signal line 109.

[0039] Each scanning line 107 corresponds to any one of the pixels 101 arranged in m rows and n columns in the pixel section 100. Each signal line 109 is electrically connected to n pixels 101 arranged in a row. , m pixels 101 arranged in any one of the columns of the pixels 101 arranged in m rows and n columns. Both m and n are integers equal to or greater than 1. Each capacitance line 115 is electrically connected to , n pixels 101 arranged in any one of the rows among the pixels 101 arranged in m rows and n columns. The capacitance lines 115 are electrically connected to the signal lines 109. When the pixels 101 are arranged in approximately parallel rows and columns, one of the pixels 101 arranged in m rows and n columns It is electrically connected to m pixels 101 arranged in a column.

[0040] FIG. 1B is an example of a circuit diagram of a pixel 101 included in the semiconductor device shown in FIG. In the pixel 101 shown in FIG. 1B, the gate electrode is electrically connected to the scanning line 107, and the source A transistor 103 having an electrode electrically connected to a signal line 109 and a transistor The other electrode is electrically connected to the drain electrode of the capacitor 103, and supplies a constant potential. The capacitor element 105 electrically connected to the line 115 and the pixel electrode are connected to the drain of the transistor 103. The pixel electrode is electrically connected to one of the electrodes of the capacitor element 105 and the pixel electrode. The electrode (opposite electrode) of the liquid crystal element 108 is electrically connected to the wiring that supplies the common potential. and,

[0041] The circuit diagram of the pixel 101 included in the semiconductor device shown in FIG. 1A is not limited to FIG. It can be illustrated as FIG. 1(C).

[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 effect of the liquid crystal is controlled by the electric field applied to the liquid crystal (horizontal electric field, This includes longitudinal or oblique electric fields.

[0043] Next, a specific example of the configuration of the pixel 101 of the liquid crystal display device will be described. A plan view is shown in Fig. 2. In Fig. 2, several components such as the counter electrode and the liquid crystal element are not shown. The description of the elements is 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 drawing). The signal lines 109 extend in a direction substantially perpendicular to the scanning lines 107 (up and down in the drawing). The capacitance line 115 is provided so as to extend in a direction parallel to the scanning line 107. The scanning lines 107 and the capacitance lines 115 are connected to the scanning line driving circuit 104 (FIG. 1( A)), and the signal line 109 is electrically connected to the signal line driver circuit 106 (see FIG. 1( A) is electrically connected to the

[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 and a gate insulating film. a gate electrode, a gate insulating film (not shown in FIG. 2), a source electrode, and a drain electrode. Note that the region of the scan line 107 that overlaps with the semiconductor film 111 is the region of the transistor 10 The signal line 109 functions as a gate electrode of the semiconductor film 111. The conductive film 113 functions as a source electrode of the transistor 103. The region overlapping with the gate electrode 11 functions as the drain electrode of the transistor 103. The gate electrode, the source electrode, and the drain electrode are connected to the scanning line 107, the signal line 109, and the The scanning line 107 may be referred to as a conductive film 113. Therefore, the scanning line 107 blocks the light from the backlight. As a result, the semiconductor film 111 included in the transistor is not irradiated with light. Therefore, fluctuations in electrical characteristics can be suppressed.

[0046] In addition, oxide semiconductors can reduce the off-state current of transistors by treating them under appropriate conditions. In one embodiment of the present invention, an oxide semiconductor is used for the semiconductor film 111 because the amount of charge can be reduced. This allows the power consumption of the semiconductor device to be reduced.

[0047] In this embodiment, the scanning line 107 is connected to the gate electrode 107a of the transistor 103. The signal line 109 includes the source electrode 109a of the transistor 103, and the conductive film 113 The conductive film 113 includes a drain electrode 113a of the transistor 103. In FIG. 2, the pixel electrode 121 is electrically connected to the In the following description, the gate electrode of a transistor is represented by When referring to the source electrode of a transistor, the scanning line 107 is used. It may be referred to as signal line 109.

[0048] The capacitance element 105 is provided in a region surrounded by the capacitance line 115 and the signal line 109 in the pixel 101. The capacitor 105 is electrically connected to a capacitor line 115. 5 is an electrode 122 made of a light-transmitting conductive material and a light-transmitting semiconductor film 1 19, a part of the same layer as the layer forming the gate insulating film 127 of the transistor 103 (FIG. 2 (not shown) is sandwiched between the capacitor 105. That is, the capacitor 105 has light-transmitting properties.

[0049] In this way, since the electrode 122 and the semiconductor film 119 are transparent, a capacitance is formed in the pixel 101. The element 105 can be formed large (large area). A semiconductor device having an increased capacitance can be obtained. This is one of the reasons for the decrease in aperture ratio, as it blocks light from the backlight, etc. In a device such as a high-resolution liquid crystal display, the area occupied by one pixel becomes smaller. However, it is difficult to secure a sufficient charge capacity and improve the aperture ratio at the same time. Since the capacitor 105 has a light-transmitting property, the capacitor can be provided in the opening of the pixel. Therefore, it is possible to increase the aperture ratio while obtaining a sufficient charge capacity in each pixel. Typically, high-resolution monitors have pixel densities of 200 ppi or more, or even 300 ppi or more. The present invention can be suitably used for a semiconductor device. Even in this case, the aperture ratio can be increased, so the light from light source devices such as backlights can be used efficiently. This can be used frequently, and the power consumption of the display device can be reduced.

[0050] Since the capacitor 105 shown in this embodiment mode has a light-transmitting property, the capacitor is large and can be used in a pixel. Therefore, it is possible to increase the aperture ratio while ensuring a sufficient charge capacity. As a result, a semiconductor device with excellent display quality can be obtained. As the semiconductor film 119 having the above structure, for example, an oxide semiconductor can be used.

[0051] Next, the characteristics of a transistor using an oxide semiconductor will be described. The transistor is an n-channel transistor. Defects can generate carriers, which degrade the electrical characteristics and reliability of the transistor. For example, the threshold voltage of a transistor may be shifted in the negative direction, and the gate voltage When the gate voltage is 0V, the drain current may flow. A transistor in which drain current flows when A transistor that can be considered as having no drain current when the gate voltage is 0V. This characteristic is called a normally-off characteristic.

[0052] Therefore, when an oxide semiconductor is used for the semiconductor film 111, the oxide semiconductor It is preferable that defects contained in the film, typically oxygen vacancies, are reduced as much as possible. For example, the g value measured by electron spin resonance when the magnetic field was applied parallel to the film surface was 1.93. The spin density (corresponding to the defect density contained in the oxide semiconductor film) is below the detection limit of the measuring instrument. Defects contained in the oxide semiconductor film, typically, oxide defects, are preferably reduced to the following level. By reducing the pixel deficiency as much as possible, the transistor 103 can have normally-on characteristics. This can suppress the generation of the electric charge, thereby improving the electrical characteristics and reliability of the semiconductor device.

[0053] The negative shift in the threshold voltage of a transistor is not only due to oxygen vacancies, but also to oxide semiconductors. It can also be caused by hydrogen (including hydrogen compounds such as water) contained in the conductor. The hydrogen contained in the oxide semiconductor reacts with the oxygen that bonds with the metal atoms to form water, and A defect (which can also be called an oxygen vacancy) is formed in the lattice where oxygen has been desorbed (or the part where oxygen has been desorbed). 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 normally-on characteristics. It is easy to become.

[0054] Therefore, when an oxide semiconductor is used for the semiconductor film 111, the oxide semiconductor It is preferable that the film has as little hydrogen as possible. Secondary Ion Mass Spectrometry (SIMS) The hydrogen concentration obtained by spectrometry was 5×10 18 atoms / cm 3 Not yet less than 1×10 18 atoms / cm 3 Less than or equal to 5 × 10 17 at oms / cm 3 or less, more preferably 1 × 10 16 atoms / cm 3 The following applies.

[0055] The semiconductor film 111 is also formed of an alkali metal or aluminum oxide, which is 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. This sometimes happens.

[0056] In addition, when nitrogen is contained in the oxide semiconductor film that is the semiconductor film 111, the electrons that are carriers This increases the carrier density and makes it easier to become n-type. Transistors using oxide semiconductors tend to be normally-on. In the semiconductor film, it is preferable that nitrogen is reduced as much as possible. For example, the nitrogen concentration is 5 x 10 18 atoms / cm 3 It is preferable to do the following:

[0057] In this way, impurities (hydrogen, nitrogen, alkali metals or alkaline earth metals, etc.) can be removed. The semiconductor film 111 is formed by reducing the amount of ions contained in the oxide semiconductor film as much as possible and purifying it to a high degree. This can prevent the transistor 103 from becoming normally on, and the off-current of the transistor 103 can be reduced. Therefore, a semiconductor device having good electrical characteristics can be manufactured. In addition, a semiconductor device with improved reliability can be manufactured.

[0058] Note that the off-state current of a transistor using a highly purified oxide semiconductor film is low. This can be proved by various experiments. For example, when the channel width W is 1×10 6 Channel length L in μm Even if the device has a thickness of 10 μm, the voltage between the source and drain electrodes (drain voltage) is 1 In the range of V to 10V, 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 corresponds to the value divided by the channel width of the transistor, must be 100 zA / μm or less. Also, by connecting a capacitor and a transistor, the current flowing into or out of the capacitor can be The off-state current was measured using a circuit in which charge flowing out of the transistor was controlled by the transistor. In this measurement, a highly purified oxide semiconductor film was used as a channel formation region of the transistor. The off-state current of the transistor is measured from 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 It was found that an even lower off-state current of 10 yA / μm could be obtained. A transistor including such an oxide semiconductor film has an extremely small off-state current.

[0059] Next, cross-sectional views of the dashed lines A1-A2 and B1-B2 in FIG. 2 are shown in FIG. show.

[0060] The cross-sectional structure of a pixel 101 of the liquid crystal display device is as follows. an element portion formed on the substrate 150; an element portion formed on the substrate 150; and a layer sandwiched between the two element portions. and a liquid crystal layer.

[0061] First, the structure of the element portion formed on the substrate 102 will be described. The electrode 122 serving as one electrode of the capacitor 105 and the gate of the transistor 103 A scanning line 107 that functions as an electrode and a capacitance line provided on the same surface as the scanning line 107 115. A gate insulating film is provided on the electrode 122, the scanning line 107, and the capacitance line 115. 3, the gate insulating film 127 is formed by the gate insulating film 127a. Although an example in which the gate insulating film 127b is laminated is shown, the gate insulating film 127 is a single layer. It may be a laminate of three or more layers.

[0062] A semiconductor film 111 is provided on a region of the gate insulating film 127 that overlaps with the scanning line 107. A semiconductor film 119 is provided on a region of the gate insulating film 127 that overlaps with the electrode 122. The semiconductor film 119 is formed by using a part of the same layer as the semiconductor film 111 at the same time as the semiconductor film 111. It can be formed.

[0063] A source electrode of the transistor 103 is formed on the semiconductor film 111 and the gate insulating film 127. A signal line 109 that functions as a drain electrode of the transistor 103 and a conductive film 11 that functions as a drain electrode of the transistor 103 are provided. The conductive film 113 is connected to the semiconductor film 119. On the gate insulating film 127, on the signal line 109, on the semiconductor film 111, on the conductive film 113, on the semiconductor film The insulating film 129 and the insulating film 131 functioning as protective insulating films for the transistor 103 are formed on the insulating film 119. , and an insulating film 132 are provided. An opening 117 reaching the conductive film 113 is provided in the insulating film 132. The pixel electrode 121 is provided on the insulating film 132. The insulating film 158 that functions as a An underlying insulating film is provided between the line 107, the capacitance line 115 and the gate insulating film 127. It's fine.

[0064] In this configuration, one of the pair of electrodes of the capacitor 105 is the electrode 122, and the other The electrodes are the semiconductor film 119, and the dielectric film provided between the pair of electrodes is the gate insulating film 12 It is 7.

[0065] The components of the above structure are described in detail below.

[0066] 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, glass substrates, ceramic substrates, etc. There are various substrates, such as ceramic substrates and plastic substrates, and glass substrates are made of barium borosilicate Glass, alkali-free glass such as aluminoborosilicate glass or aluminosilicate glass It is also possible to use a substrate that does not have light-transmitting properties, such as a stainless steel alloy. In this case, it is preferable to provide an insulating film on the surface of the substrate. Examples include quartz substrates, sapphire substrates, single crystal semiconductor substrates, polycrystalline semiconductor substrates, and compound semiconductor substrates. Substrates, SOI (Silicon On Insulator) substrates, etc. can also be used. Cut.

[0067] The electrode 122 is formed using a conductive material having light-transmitting properties similar to the pixel electrode 121 described later. In addition, a light-transmitting oxide semiconductor similar to the semiconductor film 111 described later can be used. The material can also be used for the electrode 122. The thickness of the electrode 122 is 5 nm or more and 300 nm or less. nm or less, preferably 10 nm or more and 150 nm or less.

[0068] Since the scanning line 107 and the capacitance line 115 carry a large current, they are preferably formed of a metal film. Representative examples include molybdenum (Mo), titanium (Ti), tungsten (W), and tantalum (Ta ), aluminum (Al), copper (Cu), chromium (Cr), neodymium (Nd), scandium A single layer structure or a layer structure using metal materials such as aluminum (Sc) or alloy materials containing these as the main components. or a laminated structure.

[0069] An example of the scanning line 107 and the capacitance line 115 is a single layer made of aluminum containing silicon. Layer structure, two-layer structure with titanium layered on aluminum, titanium layered on titanium nitride Two-layer structure: tungsten on titanium nitride, tungsten on tantalum nitride Two-layer structure with copper laminated on copper-magnesium-aluminum alloy There are three-layer structures, such as a titanium nitride structure with copper layered on top and tungsten layered on top of that. be.

[0070] In addition, the scanning line 107 and the capacitance line 115 are made of a transparent material that can be applied to the pixel electrode 121. A conductive material having the following structure 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 oxides are 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 Alternatively, nitrogen-containing In-based oxides and metal nitride films (InN, SnN, etc.) can be used. These materials have a work function of 5 eV (electron volts) or more. When an oxide semiconductor is used for the semiconductor film 111, the scan line 107 (gate of the transistor 103) By using a metal oxide containing nitrogen as the gate electrode, the threshold voltage of the transistor 103 is A transistor that can change the voltage in the positive direction and has so-called normally-off characteristics. For example, when using an In-Ga-Zn oxide containing nitrogen, at least The nitrogen concentration is higher than that of the oxide semiconductor film of the semiconductor film 111, specifically, the nitrogen concentration is 7 atomic % or more. The above In-Ga-Zn oxide 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 may develop hillocks, whiskers, or microstructures. Defects due to migration are likely to occur. To prevent aluminum migration, , aluminum, such as molybdenum, titanium, tungsten, etc., which have a melting point higher than aluminum. It is preferable to use a metal material with high migration resistance. To prevent defects caused by copper and the diffusion of copper elements, materials other than copper, such as molybdenum, titanium, and tungsten, are used. It is preferable to laminate a metal material having a higher melting point than the metal material.

[0073] The gate insulating film 127 is made of, for example, silicon oxide, silicon oxynitride, silicon nitride oxide, or nitride. silicon oxide, aluminum oxide, hafnium oxide, gallium oxide or Ga-Zn based metals The semiconductor film 11 is formed in 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 1, 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 provided with an insulating film having a barrier property against oxygen, hydrogen, water, etc. By this, oxygen can be diffused from the oxide semiconductor film, which is the semiconductor film 111, to the outside and from the outside. Therefore, it is possible to prevent hydrogen, water, and the like from entering the oxide semiconductor film. Examples of insulating films having a barrier property against the above include aluminum oxide, aluminum oxynitride, Gallium oxide, gallium oxynitride, yttrium oxide, yttrium oxynitride, hafnium oxide Examples include hafnium, hafnium oxynitride, and silicon nitride.

[0075] Generally, a capacitance element is made up of two opposing electrodes and a dielectric sandwiched between them. The thinner the electrode (the shorter the distance between the two opposing electrodes) and the higher the dielectric constant of the dielectric, However, if the dielectric is made thinner to increase the capacitance of the capacitive element, The leakage current between the two electrodes (hereinafter referred to as "leak current") is likely to increase. In addition, the dielectric strength of the capacitance element is likely to decrease.

[0076] Not only the capacitor element 105 but also the gate electrode (scanning line 107) of the transistor 103, the gate The overlapping portion of the insulating film 127 and the semiconductor film 111 also functions as the above-mentioned capacitor element (hereinafter The gate insulating film 127 is also referred to as a "gate capacitance." A channel is formed in the region overlapping the gate electrode. The formation region functions as two electrodes of the capacitor element, and the gate insulating film functions as the dielectric of the capacitor element. It is preferable that the gate capacitance is large, but it is necessary to increase the gate capacitance. If the insulating film 127 is made thinner, problems such as an increase in the leakage current and a decrease in the dielectric strength voltage mentioned above will occur. It becomes more likely to occur.

[0077] Therefore, 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 When the capacitance between the gate electrode and the semiconductor film 111 is It will be possible to secure sufficient

[0078] For example, if a high-k material with a large dielectric constant is used as the gate insulating film 127, Even if the insulating film 127 is made thick, the capacitance is the same as when silicon oxide is used for the gate insulating film 127. Since the amount of the gate electrode can be reduced, the leakage current generated between the gate electrode and the semiconductor film 111 can be reduced. In addition, a wiring formed using the same layer as the gate electrode and another wiring overlapping the wiring may be formed using the same layer as the gate electrode. The leakage current occurring between the gate insulating film 127 and the gate insulating film 128 can be reduced. It may also have a laminated structure with the above other materials.

[0079] The gate insulating film 127 preferably has the following laminated structure: A silicon nitride film with a small amount of defects is provided as the silicon nitride film, and a second silicon nitride film is formed on the first silicon nitride film. a silicon nitride film having a small amount of hydrogen desorption and ammonia desorption is provided as the silicon nitride film; On the second silicon nitride film, any of the oxide insulating films listed in the gate insulating film 127 is formed. It is preferable to provide such a function.

[0080] The second silicon nitride film is a film in which the amount of desorption of hydrogen molecules is 5× 10 21 molecules / cm 3 Less than 3 x 10 21 molecules / cm 3 The following is more preferably is 1 x 10 21 molecules / cm 3 The number of ammonia molecules released is 1 × 10 22 molecule / cm 3 Less than 5 x 10 21 molecules / cm 3or less, more preferably 1 × 10 21 molecules / cm 3 It is preferable to use a nitride insulating film having the following properties: The second silicon nitride film is used as a part of the gate insulating film 127, The film 127 is a gate insulating film having a small amount of defects and a small amount of hydrogen and ammonia desorption. As a result, the hydrogen and nitrogen contained in the gate insulating film 127 are The amount of transfer to the semiconductor film 111 can be reduced.

[0081] In a transistor using an oxide semiconductor, If trap states (also called interface states) exist in the gate insulating film, the threshold of the transistor The shift in the threshold voltage, typically in the negative direction, and the The sub-threshold 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 a low defect content 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, This can reduce the negative shift of the threshold voltage and suppress the increase in the S value.

[0082] The thickness of the gate insulating film 127 is 5 nm or more and 400 nm or less, and more preferably 10 nm or more. It is preferable to set the thickness to 300 nm or less, and more preferably to set the thickness to 50 nm or more and 250 nm or less.

[0083] The semiconductor film 111 and the semiconductor film 119 are oxide semiconductor films. The semiconductor film 111 may have an crystalline structure, a single crystal structure, or a polycrystalline structure. The thickness is 1 nm or more and 100 nm or less, preferably 1 nm or more and 50 nm or less, and more preferably is preferably 1 nm or more and 30 nm or less, and more preferably 3 nm or more and 20 nm or less.

[0084] As an oxide semiconductor that can be used for the semiconductor film 111 and the semiconductor film 119, The voltage is 2 eV or more, preferably 2.5 eV or more, and more preferably 3 eV or more. As shown in the figure, by using an oxide semiconductor with a wide energy gap, The current can be reduced.

[0085] The oxide semiconductor applicable to the semiconductor film 111 is at least indium (In) or zinc (Ni). It is preferable that lead (Zn) is contained. Alternatively, it is preferable that both In and Zn are contained. In addition, in order to reduce variations in the electrical characteristics of transistors using the oxide semiconductor, In addition, it is preferable to have one or more stabilizers.

[0086] Stabilizers include gallium (Ga), tin (Sn), hafnium (Hf), and aluminum. Aluminum (Al) or zirconium (Zr). Also, other stabilizers The lanthanides are 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, Ytterbium, Lutetium, etc. do.

[0087] Examples of oxide semiconductors that can be used for the semiconductor films 111 and 119 include oxide semiconductors such as Semiconductors include indium oxide, tin oxide, zinc oxide, and oxides containing two metals. In-Zn oxides, Sn-Zn oxides, Al-Zn oxides, Zn-Mg oxides, Sn-Mg oxide, In-Mg oxide, In-Ga oxide, and oxide containing three types of metals In-Ga-Zn oxide (also written as IGZO), In-Al-Zn oxide oxides, In-Sn-Zn oxides, Sn-Ga-Zn oxides, Al-Ga-Zn oxides Sn-Al-Zn oxides, In-Hf-Zn oxides, In-Zr-Zn oxides , In-Ti-Zn oxide, In-Sc-Zn oxide, In-Y-Zn oxide, I n-La-Zn oxide, In-Ce-Zn oxide, In-Pr-Zn oxide, In -Nd-Zn oxide, In-Sm-Zn oxide, In-Eu-Zn oxide, In- Gd-Zn oxide, In-Tb-Zn oxide, In-Dy-Zn oxide, In-H Oxide based on Zn, In-Er-Zn, In-Tm-Zn, In-Yb -Zn-based oxides, In-Lu-Zn-based oxides, and oxides containing four metals, such as In-S n-Ga-Zn oxide, In-Hf-Ga-Zn oxide, In-Al-Ga-Zn oxide Oxides, In-Sn-Al-Zn oxides, In-Sn-Hf-Zn oxides, In-H f-Al-Zn oxides can be used.

[0088] Here, the In-Ga-Zn oxide is an oxide having In, Ga, and Zn as its main components. The ratio of In, Ga, and Zn is not important. Metal elements may also be included.

[0089] In addition, as an oxide semiconductor, InMO3(ZnO) mUsing materials expressed as (m>0) M may be one or more metal elements selected from Ga, Fe, Mn, and Co. The metal element or the stabilizer element is also an oxide semiconductor. In2SnO5(ZnO) n Materials expressed as (n>0) may also be used.

[0090] For example, In:Ga:Zn=1:1:1 (=1 / 3:1 / 3:1 / 3), In:Ga:Z n=2:2:1 (=2 / 5:2 / 5:1 / 5), or In:Ga:Zn=3:1:2 Use In-Ga-Zn metal oxide with an atomic ratio of (=1 / 2:1 / 6:1 / 3) Alternatively, In:Sn:Zn=1:1:1 (=1 / 3:1 / 3:1 / 3), I n: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) It is recommended to use the atomic ratio of the metal oxide. Includes a 20% variation in eggplant.

[0091] However, the semiconductor properties and electrical properties required (field effect mobility, threshold voltage, etc.) are not limited to these. It is sufficient to use a material with an appropriate composition depending on the required semiconductor device (such as the minimum voltage, the variation, etc.). To obtain conductor properties, the carrier density, impurity concentration, defect density, number of metal elements and oxygen atoms, etc. It is preferable to make the ratio, interatomic distance, density, etc. appropriate. For example, In-Sn-Zn High field-effect mobility can be obtained relatively easily with In-Ga- Even in Zn-based oxides, the field-effect mobility can be increased by reducing the defect density in the bulk. This can be done.

[0092] A signal line 109 functions as the source electrode of the transistor 103. The conductive film 113 functioning as a drain electrode is made of the same material as the scanning line 107 and the capacitor line 115. The insulating film may have a single layer structure or a laminated structure.

[0093] The insulating film 129 and the insulating film 131 function as protective insulating films for the transistor 103. The film 132 can be made of the same material as the gate insulating film 127. It is preferable that the insulating film 29 and the insulating film 131 are oxide insulating films, and the insulating film 132 is a nitride insulating film. In addition, by using a nitride insulating film as the insulating film 132, impurities such as hydrogen and water can be prevented from entering from the outside. It is possible to prevent the insulating film 12 from penetrating into the transistor 103 (particularly the semiconductor film 111). 9 does not need to be provided.

[0094] In addition, one or both of the insulating films 129 and 131 may contain oxygen having a stoichiometric composition. It is preferable that the oxide insulating film contains more oxygen than the insulating film. The oxide insulating film is formed by insulating a semiconductor film having a thickness of 100 μm or less, and the thickness of the insulating film is 100 μm or less. The oxygen vacancies can be filled by transferring the oxygen to the oxide semiconductor film. The amount of oxygen molecules released measured by TDS analysis (hereinafter referred to as TDS analysis) is 1.0 x 10 18 molecules / cm 3 By using the oxide insulating film described above, The oxygen vacancies caused by the insulating film 129 and / or the insulating film 131 can be compensated for. In both cases, there are regions containing excess oxygen compared to the stoichiometric composition (oxygen excess regions). The insulating film may be an oxide insulating film that is present at least in a region overlapping with the semiconductor film 111. The presence of the oxygen-excess region prevents oxygen from being released from the oxide semiconductor film. The oxygen contained in the oxygen-excess region is moved to the oxide semiconductor film to fill the oxygen vacancies. This makes it possible to:

[0095] When the insulating film 131 is an oxide insulating film containing more oxygen than the oxygen that satisfies the stoichiometric composition, In this case, the insulating film 129 is preferably an oxide insulating film that transmits oxygen. In 29, all oxygen that enters the insulating film 129 from the outside passes through the insulating film 129 and moves. Some oxygen remains in the insulating film 129 without being oxidized. Therefore, some oxygen migrates from the insulating film 129 to the outside. An insulating oxide film with a large number of insulating films is preferable.

[0096] In addition, the insulating film 129 is in contact with the oxide semiconductor film, which is the semiconductor film 111, and therefore, The oxide insulating film is not only transparent but also reduces the interface state with the semiconductor film 111. For example, the insulating film 129 is preferably an oxide insulating film having a lower defect density than the insulating film 131. 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=2.001 is the spin density of the dangling bonds contained in the insulating film 129. corresponds to the abundance of

[0097] The thickness of the insulating film 129 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 131 can be set to 30 nm or more, preferably 10 nm or more and 30 nm or less. The thickness can be 0 nm or more and 500 nm or less, preferably 150 nm or more and 400 nm or less. do.

[0098] When the insulating film 132 is a nitride insulating film, one or both of the insulating film 129 and the insulating film 131 It is preferable that the insulating film has a barrier property against nitrogen. For example, a dense oxide insulating film By forming a film, it is possible to provide a barrier against nitrogen. Specifically, at 25°C, Oxide insulation with an etching rate of 10 nm / min or less when using 0.5 wt% hydrofluoric acid It is preferably a film.

[0099] Note that one or both of the insulating film 129 and the insulating film 131 may be formed using silicon oxynitride or silicon nitride. 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 atoms / cm 3 More than 1×10 20 atoms / cm 3 It is preferable to do the following. By setting the above, the amount of nitrogen transferred to the semiconductor film 111 included in the transistor 103 can be reduced. In addition, by doing so, defects in the oxide insulating film itself containing nitrogen can be reduced. The amount of recession can be reduced.

[0100] As the insulating film 132, a nitride insulating film with a low hydrogen content may be provided. For example, the amount of released hydrogen molecules measured by TDS analysis is 5.0 × 10 21 molecules / cm 3less than 3.0 x 10 21 molecules / cm 3 is less than Preferably 1.0 x 10 21 molecules / cm 3 It is a nitride insulating film having a thickness of less than 100 nm.

[0101] The insulating film 132 has a thickness that can suppress the intrusion of impurities such as hydrogen and water from the outside. For example, 50 nm or more and 200 nm or less, preferably 50 nm or more and 150 nm or less More preferably, it can be set to 50 nm or more and 100 nm or less.

[0102] The pixel electrode 121 is made of indium tin oxide, indium oxide containing tungsten oxide, or oxide. Indium zinc oxide containing tungsten oxide, indium oxide containing titanium oxide, Indium tin oxide containing titanium, indium zinc oxide, indium with silicon oxide The insulating layer 11 is formed of a light-transmitting conductive material such as aluminum tin oxide.

[0103] Next, the structure of the element portion formed on the substrate 150 will be described. a film 152, and an electrode (opposite electrode 15) provided on the light-shielding film 152 so as to face the pixel electrode 121; 4) is provided on the counter electrode 154. An insulating film 156 that functions as an alignment film is provided on the counter electrode 154. It is provided.

[0104] The light-shielding film 152 prevents the transistor 103 from being irradiated with light from a backlight or external light. The light-shielding film 152 is formed using a material such as metal or organic resin containing a pigment. The light-shielding film 152 is formed not only on the transistor 103 of the pixel 101 but also on the scanning Areas other than the pixel section 100, such as the signal line driving circuit 104, the signal line driving circuit 106 (see FIG. 1), etc. It may also be provided in.

[0105] 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.

[0106] The counter electrode 154 is provided by appropriately using the same light-transmitting conductive material as the pixel electrode 121. .

[0107] The liquid crystal element 108 includes a pixel electrode 121, a counter electrode 154, and a liquid crystal layer 160. The insulating film 158, which functions as an alignment film, is provided in the element portion of the substrate 102, and the insulating film 158 is provided in the element portion of the substrate 150. A liquid crystal layer 160 is sandwiched between insulating films 156 that function as alignment films provided in the element section. The pixel electrode 121 and the counter electrode 154 overlap with each other via a liquid crystal layer 160.

[0108] Here, the connections of the components included in the pixel 101 shown in this embodiment are shown in FIG. ) and the cross-sectional view shown in FIG.

[0109] FIG. 1C is an example of a detailed circuit diagram of a pixel 101 included in the semiconductor device shown in FIG. 1A. As shown in FIG. 1C and FIG. 3, the transistor 103 has a gate electrode 107a. a scanning line 107 including a source electrode 109a, a signal line 109 including a drain electrode 113a; and a conductive film 113 containing the same.

[0110] In the capacitor 105, the electrode 122 connected to the capacitor line 115 functions as one electrode. In addition, the semiconductor film 119 connected to the conductive film 113 including the drain electrode 113a is The gate insulating film 119 functions as an electrode. The insulating film 127 functions as a dielectric film.

[0111] The liquid crystal element 108 includes a pixel electrode 121, a counter electrode 154, and a pixel electrode 121 and a counter electrode 154. It consists of a liquid crystal layer 160 disposed between the electrodes.

[0112] In the capacitor 105, the semiconductor film 119 has the same structure as the semiconductor film 111. can also function as an electrode of the capacitor 105. By controlling the potential, the semiconductor film 119 is made n-type, and the conductivity of the semiconductor film 119 is increased. In this case, the semiconductor film 119 can function as one electrode of the capacitor. The capacitance element 105 can be made to function as a MOS capacitor. The potential applied to the line 115 is set as follows: 08 (see Figure 1(C)). In order to keep the semiconductor film 119 always n-type, the potential of the capacitance line 115 is always set to the pixel potential. The threshold voltage of the capacitance element 105 (MOS capacitor) is higher than the potential applied to the element electrode 121. The dielectric film of the capacitor 105 and the transistor 103 must be set to a value higher than the reference voltage. Therefore, the potential of the capacitance line 115 is applied to the pixel The potential applied to the electrode 121 is set higher by at least the threshold voltage of the transistor 103. In this way, the semiconductor film 119 becomes n-type, and the conductivity of the semiconductor film 119 is increased. It can improve sexuality.

[0113] In addition, the insulating film 129 provided over the semiconductor film 111 and the semiconductor film 119 is made of an insulating material that is impermeable to oxygen. and an oxide insulating film that reduces the interface state between the semiconductor film 111 and the semiconductor film 119. The insulating film 131 is formed of an oxide insulating film including an oxygen excess region or an oxygen insulating film having a stoichiometric composition. By using an oxide insulating film containing more oxygen than the semiconductor film 111, the semiconductor film 119 Oxygen can be easily supplied to a certain oxide semiconductor film, and oxygen from the oxide semiconductor film can be easily supplied to the certain oxide semiconductor film. The oxygen contained in the insulating film 131 is prevented from being desorbed and is transferred to the oxide semiconductor film. This makes it possible to compensate for oxygen vacancies in the oxide semiconductor film. This can prevent the capacitor 103 from becoming normally on, and 05 (MOS capacitor) is applied to the capacitance line 115 so that it is always in a conductive state. Since the potential can be controlled, the electrical characteristics and reliability of the semiconductor device can be improved. This can be done.

[0114] In addition, by using a nitride insulating film as the insulating film 132 provided over the insulating film 131, The semiconductor film 111 and the semiconductor film 119 are prevented from being penetrated by impurities such as hydrogen and water from the insulating layer. Furthermore, a nitride insulating film with a low hydrogen content can be provided as the insulating film 132. This suppresses fluctuations in the electrical characteristics of the transistor and the capacitance element 105 (MOS capacitor). This can be done.

[0115] In addition, the capacitance element 105 can be formed large (with a large area) within the pixel 101. As a result, a semiconductor device can be obtained that has an increased aperture ratio and an increased charge capacity. By increasing the aperture ratio, a semiconductor device with good display quality can be obtained.

[0116] In the semiconductor device according to one embodiment of the present invention, the polarization axis of the polarizing member (polarizing substrate) is shielded from light. The display mode of the semiconductor device is controlled by applying a voltage. When the liquid crystal element 108 is not turned on, it is in a normal state where it does not transmit light from a light source device such as a backlight. By using the black layer, the area where the light-shielding film 152 of the pixel 101 is provided can be reduced or eliminated. As a result, pixel densities of 200 ppi or more, or even 300 ppi or more, can be achieved. Even when each pixel is small, as in the case of certain high-resolution display devices, the aperture ratio can be increased. Moreover, the aperture ratio can be further increased by using a light-transmitting capacitor element.

[0117] <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 with reference to FIG. 4 and 5.

[0118] First, the electrodes 122 are formed on the substrate 102, the scanning lines 107 and the capacitance lines 115 are formed, and the electrodes 122 are then formed on the substrate 102. A gate insulating film 127 is formed to cover the electrode 122, the scanning line 107 and the capacitance line 115. A semiconductor film 111 is formed in the area of ​​the gate insulating film 127 that overlaps with the scanning line 107, and a gate insulating film 127 is formed on the semiconductor film 111. A semiconductor film 119 is formed in a region of the film 127 that overlaps with the electrode 122 (see FIG. 4A).

[0119] The electrode 122 is made of a conductive material having the same light-transmitting properties as the pixel electrode 121 listed above. A film is formed on the substrate 102, and a photolithography method, an ink jet method, or the like is applied to the film. A resist mask is formed by etching the film selectively using the resist mask. The film can be processed by either dry etching or wet etching. After etching is completed, the resist mask is removed. Alternatively, the electrode 122 can be formed using a light-transmitting oxide semiconductor material.

[0120] In addition, it is possible to form a pattern of any shape on a conductive layer, an insulating layer, a semiconductor layer, etc. by using a photolithography method. The process of forming a resist mask is called a photolithography process. After the mask is formed, etching and ion implantation processes are performed, and then the resist mask is removed. Therefore, unless otherwise specified, the term "photolithography" used in this specification The process includes steps from forming a resist mask to removing the resist mask. do.

[0121] In this embodiment, an oxide semiconductor having a thickness of 100 nm is formed on the substrate 102 as the electrode 122. After the electrode 122 is formed, a step of adding a dopant to the electrode 122 may be performed. By adding a dopant to the electrode 122, the oxide semiconductor becomes n-type, and the conductive layer of the electrode 122 The n-type oxide semiconductor can function as a conductive film. Dopants to increase conductivity include boron, nitrogen, fluorine, and aluminum. , phosphorus, arsenic, indium, tin, antimony, rare gas elements, etc. can be used. The above elements can be added to the electrode 122 by ion implantation or ion doping. The above elements can also be added by exposing the electrode 122 to plasma containing the above elements. It is possible.

[0122] The scanning lines 107 and the capacitance lines 115 are formed by forming a conductive film using the materials listed above. The conductive film can be formed by forming a mask on the film and processing the film using the mask. uses various film formation methods such as evaporation, CVD, sputtering, and spin coating. The thickness of the conductive film is not particularly limited, and the formation time and the desired resistivity can be adjusted. The mask can be determined by taking into consideration the above. The conductive film can be processed by dry etching. This can be done by either or both of etching and wet etching.

[0123] The gate insulating film 127 is formed by using various film forming methods such as CVD or sputtering. It can be achieved.

[0124] When gallium oxide is used for the gate insulating film 127, MOCVD (Metal Organic Chemical Vapor Deposition (OCVD) method It can be achieved.

[0125] When an oxide semiconductor is used for the electrode 122, the conductivity of the electrode 122 can be increased by For this purpose, a nitride insulating film may be used in the region of the gate insulating film 127 that contacts the electrode 122. By performing heat treatment with the nitride insulating film in contact with 122, the nitrogen contained in the nitride insulating film is removed. The dopant can be transferred to the electrode 122. Therefore, the step of adding the dopant can be omitted. This makes it possible to reduce the manufacturing cost of semiconductor devices and improve the yield of semiconductor devices. Cut.

[0126] The semiconductor film 111 and the semiconductor film 119 are formed using any of the oxide semiconductors listed above. a mask is formed over the oxide semiconductor film; and the oxide semiconductor film is processed using the mask. The oxide semiconductor film can be formed by a sputtering method, a coating method, a pulse laser, or the like. It can be formed by vapor deposition, laser ablation, or other methods. By this, the semiconductor film 111 and the semiconductor film 119 isolated from each other are directly formed on the gate insulating film 127. When the oxide semiconductor film is formed by a sputtering method, The power supply for generating the noise can be an RF power supply, an AC power supply, or a DC power supply. The sputtering gas may be a rare gas (typically argon), Oxygen, rare gas, and mixed gas of oxygen are used as appropriate. In the case of mixed gas of rare gas and oxygen, It is preferable to increase the gas ratio of oxygen to rare gas. The mask may be appropriately selected depending on the composition of the oxide semiconductor film. The resist mask may be formed by a photolithography process. The oxide semiconductor film is processed by either dry etching or wet etching or both. The etching process can be tailored to the material so that the desired shape can be etched. The conditions (etching gas, etching solution, etching time, temperature, etc.) are set appropriately.

[0127] After the semiconductor film 111 and the semiconductor film 119 are formed, a mask is formed to cover the semiconductor film 111. A dopant may be added to make the semiconductor film 119 n-type and increase the conductivity. Dopants to increase conductivity include boron, nitrogen, fluorine, aluminum, and phosphorus. arsenic, indium, tin, antimony, rare gas elements, etc. can be used. The above elements can be added to the semiconductor film 119 by ion implantation or ion doping. The above elements can also be added by exposing the semiconductor film 119 to plasma containing the above elements. The n-type oxide semiconductor can function as a conductive film.

[0128] After the semiconductor film 111 and the semiconductor film 119 are formed, or after the semiconductor film 119 is formed, a dopant is added to increase the conductivity. After the addition of the nitrate, heat treatment is performed to form the oxide semiconductor film, which is the semiconductor film 111 and the semiconductor film 119. It is preferable to perform dehydrogenation or dehydration. The temperature of the heat treatment is typically 15 0°C or higher and lower than the substrate strain point, preferably 200°C or higher and 450°C or lower, more preferably 300°C or higher The temperature is higher than or equal to 450° C. inclusive. This may be performed on an oxide semiconductor film before processing.

[0129] In this heat treatment, the heat treatment device is not limited to an electric furnace, and may be a medium such as a heated gas. The apparatus may be an apparatus that heats the object to be treated by thermal conduction or thermal radiation from the object. For example, GRTA (Gas Rapid Thermal Anneal) equipment, LRTA (La RTA (Rapid Thermal Anneal) equipment, etc. The LRTA device can be used with a halogen lamp. lamps, metal halide lamps, xenon arc lamps, carbon arc lamps, high-pressure natri 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.

[0130] The heat treatment is carried out in a gas atmosphere containing nitrogen, oxygen, or ultra-dry air (water content of 20 ppm or less, preferably 1 ppm or less, preferably 10 ppb or less of air), or rare gases (argon, helium, etc. The above-mentioned nitrogen, oxygen, ultra-dry air, or rare gas may be added to hydrogen, It is preferable that the material does not contain water, etc. After heating in an inert gas atmosphere, it is heated in an oxygen atmosphere. The treatment time is set to 3 minutes to 24 hours.

[0131] 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, silicon oxide nitride, gallium oxide, hafnium oxide, yttrium oxide, oxide The insulating film can be made of aluminum, aluminum oxynitride, or the like. Silicon nitride, gallium oxide, hafnium oxide, yttrium oxide, aluminum oxide By forming the insulating layer 104 with an alkali metal or the like, impurities, typically alkali metals, water, hydrogen, etc., can be removed from the substrate 102. The base insulating film can be formed by a sputtering method or a Alternatively, it can be formed by using a CVD method.

[0132] Next, a signal line 109 that functions as the source electrode of the transistor 103, a signal line 108 that functions as the source electrode of the transistor 10 A conductive film 113 functioning as a drain electrode of the third transistor is formed (see FIG. 4B).

[0133] The signal line 109 and the conductive film 113 are made of a material that can be used for the signal line 109 and the conductive film 113. A conductive film is formed using the above-mentioned method, a mask is formed on the conductive film, 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.

[0134] Next, the semiconductor film 111, the semiconductor film 119, the signal line 109, the conductive film 113, and the gate insulating film An insulating film 128 is formed on the film 127, an insulating film 130 is formed on the insulating film 128, and an insulating film 130 is formed on the insulating film 127. An insulating film 133 is formed on the insulating film 128 and the insulating film 130 (see FIG. 5A). It is preferable that the insulating film 133 and the insulating film 134 are formed continuously. 128, the insulating film 130 and the insulating film 133 are prevented from being contaminated with impurities at their respective interfaces. can.

[0135] The insulating film 128 is formed by a CVD method or a sputtering method using a material that can be used for the insulating film 129. The insulating film 130 can be formed by various film formation methods such as a film deposition method. The insulating film 133 can be formed using a material applicable to the insulating film 132. It can be formed using:

[0136] When an oxide insulating film that reduces the interface state with the semiconductor film 111 is used as the insulating film 129, The insulating film 128 can be formed under the following conditions. The following describes the case where a silicon oxide film or a silicon oxynitride film is formed. The conditions were as follows: the substrate placed in the evacuated processing chamber of the plasma CVD device was heated to 180°C or higher. The temperature is kept at 400°C or less, more preferably 200°C to 370°C, and the raw material gas is introduced into the processing chamber. A deposition gas containing silicon and an oxidizing gas were introduced to maintain the pressure in the processing chamber at 20 Pa. The pressure in the processing chamber is set to 40 Pa or more and 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.

[0137] Representative examples of silicon-containing deposition gases include silane, disilane, trisilane, and silicon fluoride. Oxidizing gases include oxygen, ozone, nitrous oxide, and nitrogen dioxide. be.

[0138] In addition, by increasing the amount of oxidizing gas to the amount of silicon-containing deposition gas by 100 times or more, It is possible to reduce the hydrogen content in the insulating film 128 (insulating film 129) and Therefore, the number of dangling bonds contained in the insulating film 128 (insulating film 129) can be reduced. The oxygen that moves from the insulating film 130 (insulating film 131) moves to the insulating film 128 (insulating film 129). Since the insulating film 128 (insulating film) may be captured by the dangling bonds contained therein, When the dangling bonds contained in the insulating film 130 (insulating film 13) are reduced, 1) efficiently moves oxygen contained in the semiconductor film 111 and the semiconductor film 119, The oxide semiconductor film 111 and the semiconductor film 119 can be filled with oxygen vacancies. As a result, the amount of hydrogen mixed into the oxide semiconductor film can be reduced, and the oxide semiconductor It is possible to reduce oxygen vacancies contained in the conductive film.

[0139] The insulating film 131 is an oxide insulating film containing the above-mentioned 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 Here, the oxide insulating film can be formed of a silicon oxide film or a silicon oxynitride film. The formation conditions are as follows: The substrate placed in the evaporative processing chamber is heated to 180°C or higher and 260°C or lower, more preferably 18 The temperature was kept between 0°C and 230°C, and the raw material gas was introduced into the processing chamber to reduce the pressure in the processing chamber to 1 The pressure is preferably 100 Pa or more and 250 Pa or less, and more preferably 100 Pa or more and 200 Pa or less. 0.17W / cm to the electrode installed in the treatment chamber 2 More than 0.5W / cm2 The following are more preferred: Approximately 0.25W / cm 2 More than 0.35W / cm 2 The following high frequency power is supplied: do.

[0140] The source gas for the insulating film 130 can be the source gas that can be used for the insulating film 128 .

[0141] As a condition for forming the insulating film 130, high frequency power of the above power density in a processing chamber under the above pressure is used. By supplying the source gas, the decomposition efficiency in the plasma increases, oxygen radicals increase, As the oxidation of the source gas progresses, the oxygen content in the insulating film 130 becomes higher than the stoichiometric composition. However, when the substrate temperature is above this level, the bonding strength between silicon and oxygen becomes weak. As a result, the amount of oxygen in the stoichiometric composition is less than that of the oxygen in the stoichiometric composition. It is possible to form an oxide insulating film that contains a large amount of oxygen and from which part of the oxygen is released by heating. In addition, an insulating film 128 is provided on the semiconductor film 111. In this formation process, the insulating film 128 serves as a protective film for the semiconductor film 111. Even if the insulating film 130 is formed using high-density high-frequency power, damage to the semiconductor film 111 is prevented. can be suppressed.

[0142] In addition, by increasing the thickness of the insulating film 130, the amount of oxygen released by heating can be increased. Therefore, it is preferable that the insulating film 130 is thicker than the insulating film 128. By providing the film 128, it is possible to improve the coverage even when the insulating film 130 is provided thickly. Cut.

[0143] When the insulating film 132 is formed using a nitride insulating film with a low hydrogen content, the insulating film 133 is formed as follows. Here, a silicon nitride film is formed as the nitride insulating film. The formation conditions are as follows: The substrate placed in the chamber is heated to a temperature of 80°C to 400°C, more preferably 200°C to 370°C. The raw material gas is introduced into the processing chamber to maintain the pressure in the processing chamber at 100 Pa or more. The pressure is set to 50 Pa or less, preferably 100 Pa or more and 200 Pa or less, and the pressure is set to 5 ... preferably 100 Pa or more and 200 Pa or less. The object is to supply high frequency power to the electrode.

[0144] The source gas for the insulating film 133 is a deposition gas containing silicon, nitrogen, and ammonia. Representative examples of deposition gases containing silicon include silane and disilane. , trisilane, fluorinated silane, etc. The flow rate of nitrogen is The ratio is preferably 5 to 50 times, more preferably 10 to 50 times. By using ammonia as a source gas, the decomposition of silicon-containing deposition gas and nitrogen is achieved. This is because ammonia is decomposed by plasma energy or thermal energy. The energy generated by the dissociation and decomposition of the deposition gas molecules containing silicon and nitrogen This is because it contributes to the decomposition of the bonds of elementary molecules. and forming a silicon nitride film capable of suppressing the intrusion of impurities such as hydrogen and water from the outside. It is possible.

[0145] 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 transferred to the semiconductor film 111. It is preferable to compensate for oxygen vacancies in the film. The dehydrogenation or dehydration of the conductive film 119 can be appropriately performed by referring to the details of the heat treatment. Cut.

[0146] Next, the insulating film 128, the insulating film 130, and the insulating film 133 are formed in regions overlapping with the conductive film 113. An opening 117 reaching the conductive film 113 is formed (see FIG. 5B).

[0147] The opening 117 is formed by masking so that a part of the region of the insulating film 133 overlapping with the conductive film 113 is exposed. A mask is formed, and the insulating film 128, the insulating film 130, and the insulating film 133 are processed using the mask. The mask and the processing are performed on the scanning line 107 and the capacitance line 11. This can be done in the same way as in 5.

[0148] Finally, the pixel electrode 121 is formed to fabricate the element portion provided on the substrate 102. The pixel electrode 121 is made of the above-listed materials and is formed through the opening 117 (see FIG. 3). A conductive film is formed in contact with the conductive film 113, a mask is formed over the conductive film, and the mask The mask and the processing can be performed by scanning the scanning line 10. 7 and the capacitance line 115 can be performed in the same manner.

[0149] The electrode 122 may be formed so as to extend along the scanning line 107. By forming the capacitor line 115 so as to extend along the scanning line 107, the formation of the capacitor line 115 can be omitted. It can also be done as follows.

[0150] <Variation 1> In the semiconductor device according to one embodiment of the present invention, the shape of a transistor provided in a pixel is shown in FIG. The shape of the transistor is not limited to that shown in FIGS. 2 and 3, and may be changed as appropriate. For example, as shown in FIG. 6, in a pixel 151, a transistor 153 is included in a signal line 109. The source electrode of the transistor 103 is U-shaped (C-shaped, U-shaped, or horseshoe-shaped). Alternatively, the transistor may have a shape surrounding the conductive film 113 that functions as a drain electrode. By using this shape, it is possible to obtain a sufficient channel width even if the area of ​​the transistor is small. This makes it possible to ensure that the drain current (also known as the on-current) that flows when the transistor is conducting is In the pixel 151 of FIG. The configuration other than 53 is the same as in FIG.

[0151] <Variation 2> In the semiconductor device of one embodiment of the present invention, one electrode of the capacitor 105 The shape of the capacitor line 115 connected to the electrode 122 can be changed as appropriate. In order to reduce the contact resistance between the electrode 122 and the capacitor line 115, a part of the capacitor line 115 is connected to the electrode 122. 122.

[0152] A specific example of this configuration will be described with reference to FIGS. 7 to 9. Note that, here, FIGS. Only the parts different from 3 will be explained. FIG. 7 is a top view of a pixel 161 of this configuration, and FIG. 7 is a cross-sectional view taken along dashed lines A1-A2 and B1-B2 in FIG. 8 is a cross-sectional view taken along the dashed dotted line C1-C2 in FIG.

[0153] In the pixel 161 having this configuration, the capacitance line 167 is provided along the outer periphery of the electrode 122 in contact with it. The capacitor line 167 functions as the gate electrode of the transistor 103 (see FIG. 7). Since the scanning lines 107 are formed in the same process as the scanning lines 107, they may have a light-shielding property. It is preferable to form the pixel 161 in FIG. 7 in a loop shape. Other configurations of the pixel 161 in FIG. 7 are the same as those in FIG. It seems that

[0154] As shown in FIGS. 8 and 9, in the pixel 161 having this configuration, the capacitance line 167 is The electrode 122 is provided so as to cover the end of the electrode 122 of the electrode 65. The contact resistance between the electrode 122 and the capacitance line 167 is reduced, and electric charges are efficiently supplied to the capacitance element 165. It is possible.

[0155] In the configurations shown in FIGS. 7 to 9, the capacitance line 167 is formed in a loop shape. The conductive film formed in the same formation process as the line 167 is separated from the capacitance line 167 and is used as an electrode. It may be provided in contact with the outer periphery of 122.

[0156] <Variation 3> 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. Cut. FIG. 10 shows a configuration in which adjacent pixels share a capacitance line.

[0157] FIG. 10 shows the top surfaces of the pixel 401_1 and the pixel 401_2 adjacent to each other in the extension direction of the signal line 109. The pixel 401_1 and the pixel 401_2 are the pixel 101 shown in FIG. There are 15 different floor plans.

[0158] The scanning lines 107_1 and 107_2 shown in FIG. 10 are parallel to each other and have a signal The scanning line 107_1 and the scanning line 109 are provided so as to extend in a direction substantially perpendicular to the scanning line 109. Between the scanning lines 107_1 and 107_2, a capacitance line 115 is provided in parallel with the scanning lines 107_1 and 107_2. The capacitor line 115 is connected to the capacitor 405_1 provided in the pixel 401_1. and the capacitor 405_2 provided in the pixel 401_2. The top surface shape of the pixel 401_2 and the arrangement positions of the components are symmetrical with respect to the capacitance line 115. do.

[0159] The pixel 401_1 includes a transistor 103_1 and a transistor connected to the transistor 103_1. A capacitor 405_1 is provided.

[0160] The transistor 103_1 is provided in a region where the scanning line 107_1 and the signal line 109 intersect. The transistor 103_1 includes at least a semiconductor film having a channel formation region. 111_1, a gate electrode, a gate insulating film (not shown in FIG. 10), a source electrode, and a drain electrode. The overlapping region functions as the gate electrode of the transistor 103_1. The region overlapping with the semiconductor film 111_1 functions as a source electrode of the transistor 103_1. In the conductive film 113_1, a region overlapping with the semiconductor film 111_1 is a transistor. The conductive film 113_1 and the pixel electrode 121_1 function as a drain electrode of the pixel electrode 103_1. The connection is made at the opening 117_1.

[0161] The capacitor 405_1 is electrically connected to the capacitor line 115. a semiconductor film 119_1 formed of a light-transmitting oxide semiconductor; and a light-transmitting electrode. 122_1, and a layer forming a gate insulating film of the transistor 103_1 as a dielectric film. The capacitor element 405_1 is made up of a part of the same layer (not shown in FIG. 10). It has translucency.

[0162] The pixel 401_2 includes a transistor 103_2 and a transistor connected to the transistor 103_2. A capacitor 405_2 is provided.

[0163] The transistor 103_2 is provided in a region where the scanning line 107_2 and the signal line 109 intersect. The transistor 103_2 includes at least a semiconductor film having a channel formation region. 111_2, a gate electrode, a gate insulating film (not shown in FIG. 10), a source electrode, and a drain electrode. The overlapping region functions as the gate electrode of the transistor 103_2. The region overlapping with the semiconductor film 111_2 functions as a source electrode of the transistor 103_2. In the conductive film 113_2, a region overlapping with the semiconductor film 111_2 is a transistor. The conductive film 113_2 and the pixel electrode 121_2 function as a drain electrode of the pixel electrode 121_2. The connection is made at the opening 117_2.

[0164] The capacitor 405_2 is electrically connected to the capacitor line 115, similarly to the capacitor 405_1. The capacitor 405_2 is formed using a semiconductor film 11 made of a light-transmitting oxide semiconductor. 9_2, a light-transmitting electrode 122_2, and a dielectric film formed on the transistor 103_2. The gate insulating film is formed of a layer and a part of the same layer (not shown in FIG. 10). That is, the capacitor 405_2 has a light-transmitting property.

[0165] Note that the transistors 103_1 and 103_2 and the capacitor 405_1 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 element 105, its description is omitted here.

[0166] In the top view, a capacitance line is provided between two adjacent pixels, and the capacitance included in each pixel is By connecting the capacitance elements, it is possible to reduce the number of capacitance lines. Compared to a configuration in which a capacitance line is provided, the aperture ratio of the pixel can be further increased.

[0167] In addition, the electrode 122_1 and the electrode 122_2 can be connected to form one electrode. In addition, the capacitance line 115 is omitted, and the electrodes 122_1 and 122_2 are connected to the scanning line 107_1. and may extend along the scan line 107_2.

[0168] As described above, one electrode of the capacitor element is formed in the same formation process as the semiconductor film of the transistor. By using a semiconductor film having a high aperture ratio, a capacitor element having an increased charge capacity can be obtained. In addition, by increasing the aperture ratio, the display quality can be improved. A good semiconductor device can be obtained.

[0169] In addition, oxygen vacancies are reduced in the oxide semiconductor film that is the semiconductor film of the transistor, and hydrogen, nitrogen, and the like are released. Since the amount of impurities such as SiO 2 is reduced, the semiconductor device according to one embodiment of the present invention has good electrical conductivity. This results in a semiconductor device with thermal conductivity.

[0170] Note that the structure described in this embodiment mode may be used in appropriate combination with structures described in other embodiments. You can be there.

[0171] (Embodiment 2) The transistor 103 and the transistor 153 disclosed in the above embodiment are The channel forming region of 1 is formed by etching with an etching solution used for forming the signal line 109 and the conductive film 113. It is a channel etching type transistor that is exposed to etching gases. The structure applicable to the transistor 103 and the transistor 153 is limited to a channel etching type. In this embodiment, the transistor 103 and the transistor 153 An example of the structure of an applicable transistor will be described with reference to FIG.

[0172] A transistor 183 shown in FIG. 11A has a channel protective film 182 over a semiconductor film 111. The signal line 109 and the conductive film 113 are formed so as to overlap a part of the channel protective film 182. The channel protective film 182 protects the semiconductor film 111 from the The channel forming region is formed by etching the signal line 109 and the conductive film 113. Therefore, the channel protection film 182 can be formed without being exposed to the etching gas. Although the number of steps to form the signal line 109 and the conductive film 113 is increased, the semiconductor film 111 Damage is reduced.

[0173] By providing the channel protective film 182, the source electrode and the drain electrode of the transistor It is also possible to reduce the leakage current between the transistors. It becomes possible to realize this.

[0174] The channel protective film 182 can be formed using the same material as the insulating film 129. In the transistor 183, the channel protection film 182 is formed using the same material as the insulating film 129. By doing so, the formation of the insulating film 129 is omitted.

[0175] The transistor 190 shown in FIG. 11B has a signal line 109 and a conductive layer on the gate insulating film 127. The conductive film 113 is formed on the gate insulating film 127, the signal line 109, and a part of the conductive film 113. The semiconductor film 111 is formed at a position overlapping the signal line 109. Since the semiconductor film 111 is formed after the conductive film 113 is formed, the semiconductor film 111 is 09 and the conductive film 113 are exposed to the etching solution and etching gas used in forming the conductive film 113. do not have.

[0176] Note that the transistor 103 or the transistor 153 is configured as the transistor 190. Then, the semiconductor film 119 is formed on the conductive film 113 .

[0177] The transistor 200 shown in FIG. 11C is the same as the transistor 10 disclosed in the above embodiment. 3 or a structure in which a conductive film 135 is formed over the insulating film 132 of the transistor 153. The conductive film 135 is formed to overlap with at least a channel formation region of the semiconductor film 111 . The potential of the conductive film 135 is a common potential, a GND potential, an arbitrary potential, or a flow By providing the conductive film 135, it is possible to perform a reliability test (for example, Transistor 2 before and after BT (Bias Temperature) stress test The amount of fluctuation in the threshold voltage of 00 can be further reduced. The electrical characteristics of a transistor can change due to the influence of external electric fields such as static electricity. This can prevent the occurrence of defects, thereby improving the reliability of the transistor.

[0178] The conductive film 135 can function as a back gate electrode. The gate electrode and the back gate electrode are disposed so as to sandwich the channel forming region of the semiconductor layer. The back gate electrode is formed of a conductive layer and can function in the same manner as the gate electrode. In addition, the threshold voltage of the transistor is controlled by controlling the potential of the back gate electrode. In addition, the conductive film 135 and the scanning line 107 (gate electrode) are connected to each other, and The conductive film 135 may function as a second gate electrode due to the potential.

[0179] The conductive film 135 is made of the same material and in the same manner as the scanning lines 107, the signal lines 109, the pixel electrodes 121, etc. It can be formed by the method.

[0180] The transistor 183, the transistor 190, and the transistor 200 disclosed in this embodiment The structures of the transistors 103 and 153 disclosed in the above embodiments are In addition to the transistors constituting the scanning line driver circuit 101, the signal line driver circuit 102, It can also be applied to the transistors that make up 06.

[0181] Note that the structure described in this embodiment mode may be used in appropriate combination with structures described in other embodiments. You can be there.

[0182] (Embodiment 3) In this embodiment, the semiconductor device can be used for the transistor and the capacitor described in the above embodiment. One embodiment of an oxide semiconductor film that can be formed will be described.

[0183] Oxide semiconductor films are roughly classified into single-crystal oxide semiconductor films and non-single-crystal oxide semiconductor films. The single-crystal oxide semiconductor film includes an amorphous oxide semiconductor film, a microcrystalline oxide semiconductor film, a polycrystalline oxide semiconductor film, and a polycrystalline oxide semiconductor film. Physical semiconductor film, CAAC-OS (C Axis Aligned Crystalline Oxide Semiconductor film, etc.

[0184] The amorphous oxide semiconductor film has an irregular atomic arrangement in the film and is an oxide film that does not contain a crystalline component. The film is a compound semiconductor film. It does not have any crystalline parts even in the microscopic areas, and the entire film has a completely amorphous structure. A typical example is an oxide semiconductor film.

[0185] The microcrystalline oxide semiconductor film is made up of, for example, microcrystals (nanocrystals) having a size of 1 nm or more and less than 10 nm. Therefore, the microcrystalline oxide semiconductor film has a lower atomic number than the amorphous oxide semiconductor film. Therefore, the microcrystalline oxide semiconductor film has a higher order of molecular arrangement than the amorphous oxide semiconductor film. The defect level density is also low.

[0186] The CAAC-OS film is one of the oxide semiconductor films that has multiple crystal parts. The crystal part is so large that it fits inside a cube with a side length of less than 100 nm. The crystals contained in the S film are cubic with sides of less than 10 nm, 5 nm, or 3 nm. The CAAC-OS film has a smaller defect density than the microcrystalline oxide semiconductor film. The CAAC-OS film has a low density of recessed states. .

[0187] The CAAC-OS film was observed under a transmission electron microscope (TEM). When observed under a crystalline microscope, clear boundaries between the crystals, i.e., crystal boundaries, are clearly visible. It is not possible to confirm the grain boundary. It can be said that the AC-OS film is less susceptible to the decrease in electron mobility caused by grain boundaries.

[0188] The CAAC-OS film was observed by TEM from a direction roughly parallel to the sample surface (cross-sectional TEM observation). ) It can be confirmed that the metal atoms are arranged in layers in the crystalline part. Each layer has a surface on which the CAAC-OS film is formed (also referred to as a surface on which the CAAC-OS film is formed) or an uneven surface on which the CAAC-OS film is formed. The shape reflects this and is aligned parallel to the surface on which the CAAC-OS film is formed or the top surface.

[0189] On the other hand, the CAAC-OS film was observed by TEM from a direction approximately perpendicular to the sample surface (planar TEM). When observed, it was found that the metal atoms were arranged in triangular or hexagonal shapes in the crystals. However, there is no regularity in the arrangement of metal atoms between different crystal parts. stomach.

[0190] Cross-sectional and planar TEM observations revealed that the crystals in the CAAC-OS film had an orientation. It turns out that there are.

[0191] X-ray diffraction (XRD) was performed on the CAAC-OS film. For example, a CAAC-OS film with InGaZnO4 crystals was found by structural analysis using the device. In the out-of-plane analysis, a peak was observed at a diffraction angle (2θ) of approximately 31°. This peak is attributed to the (009) plane of the InGaZnO4 crystal. This indicates that the crystals of the CAAC-OS film have a c-axis orientation, and the c-axis is approximately 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.

[0192] On the other hand, in-pl X-rays are incident on the CAAC-OS film from a direction approximately perpendicular to the c-axis. In the analysis by the ane method, a peak may appear at 2θ around 56°. This is attributed to the (110) plane of the InGaZnO4 crystal. In the case of a semiconductor film, 2θ is fixed at around 56°, and the normal vector of the sample surface is set as the axis (φ axis). When the sample is rotated and analyzed (φ scan), the crystal plane equivalent to the (110) plane is detected. In contrast, in the case of the CAAC-OS film, 2θ is set to 5 Even when the φ is fixed at around 6° and scanned, no clear peak appears.

[0193] From the above, it can be concluded that the a-axis and b-axis orientations are inconsistent between different crystal regions in the CAAC-OS film. Although it is regular, 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.

[0194] The crystalline part 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 with the surface on which the CAAC-OS film is formed or the surface on which the CAAC-OS film is formed. The orientation of the CAAC-OS film is parallel to the normal vector of the top surface. When the shape is changed by etching, the c-axis of the crystal is aligned with the surface on which the CAAC-OS film is formed. Or it may not be parallel to the normal vector of the upper surface.

[0195] The crystallinity of the CAAC-OS film may not be uniform. When the crystal part of the CAAC-OS film is formed by crystal growth from the vicinity of the top surface, The area near the surface may have a higher degree of crystallinity than the area near the surface to be formed. When impurities are added to a C-OS film, the crystallinity of the region where the impurities are added changes, resulting in partial In some cases, regions of different crystallinity may be formed.

[0196] In addition, the out-of-plane method of CAAC-OS film with InGaZnO4 crystals In the analysis by , in addition to the peak at 2θ around 31°, a peak also appeared at 2θ around 36°. The peak at 2θ around 36° is due to the presence of c-axis orientation in part of the CAAC-OS film. The CAAC-OS film contains crystals that do not have a 2θ of around 31°. It is preferable that the peak is exhibited at 2θ of around 36° and that the peak is not exhibited at 2θ of around 36°.

[0197] The oxide semiconductor film may be, for example, an amorphous oxide semiconductor film, a microcrystalline oxide semiconductor film, or a CA The AC-OS film may be a laminated film having two or more kinds of films.

[0198] There are three methods for forming the CAAC-OS.

[0199] 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. The c-axis of the crystal part included in the oxide semiconductor film is aligned with the normal vector of the surface where the film is formed or the This is a method for forming crystals aligned in a direction parallel to the normal vector.

[0200] The second method is to form a thin oxide semiconductor film and then heat it at a temperature of 200°C to 700°C. By the treatment, the c-axis of the crystal part included in the oxide semiconductor film is aligned along the normal vector of the surface where the film is formed. Alternatively, it is a method of forming crystal portions aligned in a direction parallel to the normal vector of the surface.

[0201] The third method is to deposit a thin oxide semiconductor film as a first layer, and then heat the film at 200°C to 700°C. The following heat treatment is performed, and then a second oxide semiconductor film is formed. 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 crystals aligned in a specific direction.

[0202] A transistor using CAAC-OS for an oxide semiconductor film can be irradiated with visible light or ultraviolet light. Therefore, the change in electrical characteristics is small. The star has good reliability.

[0203] 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 surface, the crystalline region contained in the sputtering target is cleaved from the ab plane. The particles are split open and exfoliated as flat or pellet-shaped sputtered particles with surfaces parallel to the ab plane. In this case, the plate-shaped or pellet-shaped sputtered particles may become fused. By reaching the deposition surface while maintaining the crystalline state, CAAC-OS can be deposited. do.

[0204] In addition, the following conditions are preferably applied to form a CAAC-OS film.

[0205] 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 film formation chamber can be In addition, the impurity concentration in the deposition gas can be reduced. A deposition gas at a temperature of -80°C or lower, preferably -100°C or lower, is used.

[0206] In addition, by increasing the heating temperature of the surface to be film-formed (for example, the substrate heating temperature), After reaching the target, migration of sputtered particles occurs. 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 film formation, plate-shaped or pellet-shaped sputtering particles When it reaches the surface on which the film is to be formed, migration occurs on the surface on which the film is to be formed, resulting in sputtering. The flat surface of the particle adheres to the surface on which the film is to be formed.

[0207] In addition, increasing the oxygen ratio in the deposition gas and optimizing the power reduces plasma damage during deposition. The oxygen ratio in the deposition gas is preferably 30% by volume or more, and more preferably 100% by volume or more. The product is %.

[0208] As an example of a sputtering target, an In-Ga-Zn-O compound target is The following are the results:

[0209] InO X powder, GaO Y Powder and ZnO Z The powders are mixed in a specified number of moles, and after pressure treatment, By heat treatment at temperatures between 1000℃ and 1500℃, polycrystalline In-Ga- The Zn-based metal oxide target may be subjected to the pressure treatment while cooling. The heating may be performed while heating. X, Y, and Z are any positive numbers. The mole ratio of InO X powder, GaO Y Powder and ZnO Z Powder is 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 mixture depend on the sputtering target to be prepared. The above can be changed as appropriate.

[0210] Further, the oxide semiconductor film may have a structure in which a plurality of oxide semiconductor films are stacked. For example, the oxide semiconductor film may be a stack of a first oxide semiconductor film and a second oxide semiconductor film, and metal oxides having different atomic ratios may be used for the first oxide semiconductor film and the second oxide semiconductor film. For example, one of an oxide containing two types of metals, an oxide containing three types of metals, and an oxide containing four types of metals may be used for the first oxide semiconductor film, and an oxide containing two types of metals different from the first oxide semiconductor film, an oxide containing three types of metals, and an oxide containing four types of metals may be used for the second oxide semiconductor film. For example, one of an oxide containing two types of metals, an oxide containing three types of metals, and an oxide containing four types of metals may be used for the first oxide semiconductor film, and an oxide containing two types of metals different from the first oxide semiconductor film, an oxide containing three types of metals, and an oxide containing four types of metals may be used for the second oxide semiconductor film. oxide semiconductor film and an oxide containing three types of metals, and an oxide containing four types of metals may be used for the second oxide semiconductor film. oxide semiconductor film may be used.

[0211] The oxide semiconductor film may have a two-layer structure, and the components of the first oxide semiconductor film and the second oxide semiconductor film may be the same, and the atomic ratios of the two may be different. For example, the atomic ratio of the first oxide semiconductor film may be In:Ga:Zn = 3:1:2, and the atomic ratio of the second oxide semiconductor film may be In: Ga:Zn = 1:1:1. Further, the atomic ratio of the first oxide semiconductor film may be In: Ga:Zn = 2:1:3, and the atomic ratio of the second oxide semiconductor film may be In:Ga:Zn = 1 :3:2. Note that the atomic ratio of each oxide semiconductor film includes a variation of plus or minus 20% of the above atomic ratio as an error. Ga:Zn = 2:1:3, and the atomic ratio of the second oxide semiconductor film may be In:Ga:Zn = 1 :3:2. Note that the atomic ratio of each oxide semiconductor film includes a variation of plus or minus 20% of the above atomic ratio as an error. ratio including fluctuations of plus or minus 20% of the above atomic ratio.

[0212] At this time, in the first oxide semiconductor film and the second oxide semiconductor film, it is preferable that the atomic ratio of In and Ga in the oxide semiconductor film closer to the gate electrode (the channel side) is In≧Ga. Further, it is preferable that the atomic ratio of In and Ga in the oxide semiconductor film farther from the gate electrode (the back channel side) is In <Ga. With these stacked structures, a transistor having a high field-effect mobility can be obtained. <Ga. With these stacked structures, a transistor having a high field-effect mobility can be can be fabricated. On the other hand, by setting the atomic ratio of In to Ga in the oxide semiconductor film on the side closer to the gate electrode (channel side) as In < Ga, and the atomic ratio of In to Ga in the oxide semiconductor film on the back channel side as In ≧ Ga, the variation amount of the threshold voltage due to the change over time of the transistor and the reliability test can be reduced. The first oxide semiconductor film with an atomic ratio of In:Ga:Zn = 1:3:2 can be formed by a sputtering method using an oxide target with an atomic ratio of In:Ga:Zn = 1:3:2. It can be formed with the substrate temperature at room temperature and using argon, or a mixed gas of argon and oxygen as the sputtering gas. The second oxide semiconductor film with an atomic 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 with an atomic ratio of In:Ga:Zn = 3:1:2. Moreover, the oxide semiconductor film may have a three-layer structure, with the constituent elements of the first to third oxide semiconductor films being the same and their respective atomic ratios being different. The configuration of the oxide semiconductor film having a three-layer structure will be described using FIG. 12. The transistor shown in FIG. 12 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 can be represented by InM1

[0213] Zn (x ≧ 1, y > 1, z > 0, M1 = Ga, Hf, etc.).

[0214]

[0215]

[0215] x y z x Zn y O z (x ≧ 1, y > 1, z > 0, M1 = Ga, Hf, etc.). However, the first oxide semiconductor film 199a and the third oxide semiconductor film 19 When Ga is included in the material that makes up 9c, the ratio of Ga included is high, specifically In M1 X Zn Y O Z If X exceeds 10 for a material that can be expressed as Therefore, it is inappropriate.

[0216] The material constituting the second oxide semiconductor film 199b is InM2 x Zn y O z (x≧1 , y≧x, z>0, M2=Ga, Sn, etc.)

[0217] The conduction band minimum of the first oxide semiconductor film 199a and the conduction band minimum of the third oxide semiconductor film 199c The conduction band minimum of the second oxide semiconductor film 199b is set to be the deepest from the vacuum level compared to the bottom. The materials of the first, second, and third oxide semiconductor films are appropriately selected to form such a well-shaped structure. Select.

[0218] In the oxide semiconductor film, silicon and carbon, which are elements of Group 14, act as donors. Therefore, when silicon or carbon is contained in an oxide semiconductor film, the oxide semiconductor film As a result, the silicon and carbon contained in each oxide semiconductor film become n-type. The concentration is 3 x 10 18 / cm 3 Less than or equal to 3 x 10 17 / cm 3 In particular, The first oxide semiconductor film 199b is formed so as to prevent a large amount of Group 14 elements from being mixed into the second oxide semiconductor film 199b. The conductive 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 or surrounded by the first oxide semiconductor film 199b. 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 199b can also be called a barrier film that prevents the oxide semiconductor film 199b from being mixed into the second oxide semiconductor film 199b.

[0219] For example, when the atomic ratio of the first oxide semiconductor film 199a is 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 may be In:Ga:Zn=1:1:1. The third oxide semiconductor film 199c has an atomic ratio of In:Ga:Zn=1:1:1. It can be formed by a sputtering method using an oxide target.

[0220] Alternatively, the first oxide semiconductor film 199a may be formed of a Zn-based oxide semiconductor having an atomic ratio of In:Ga:Zn=1:3:2. The second oxide semiconductor film 199b has an atomic ratio of In:Ga:Z. an oxide semiconductor film having n=1:1:1 or In:Ga:Zn=1:3:2; The oxide semiconductor film 199c is an oxide semiconductor having an atomic ratio of In:Ga:Zn=1:3:2. It may also have a three-layer structure with a membrane.

[0221] The first to third oxide semiconductor films 199a to 199c contain the same constituent elements. Therefore, the second oxide semiconductor film 199b has a low conductivity at the interface with the first oxide semiconductor film 199a. In detail, the defect level (trap level) is The defect level at the interface between the gate insulating film 127 and the first oxide semiconductor film 199a is smaller than that 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, The amount of variation in threshold voltage due to aging and reliability testing can be reduced.

[0222] In addition, the conduction band minimum of the first oxide semiconductor film 199a and the conduction band minimum of the third oxide semiconductor film 199c are The conduction band minimum of the second oxide semiconductor film 199b is the deepest from the vacuum level compared to the conduction band minimum. The materials of the first, second, and third oxide semiconductor films are selected so as to form a well structure. By appropriately selecting This makes it possible to reduce the amount of variation in threshold voltage due to deterioration over time of transistors and reliability testing. Cut.

[0223] In addition, the first to third oxide semiconductor films 199a to 199c have different crystallinity. That is, a single-crystal oxide semiconductor, a polycrystalline oxide semiconductor, or the like may be used. The amorphous oxide semiconductor, the CAAC-OS, and the amorphous oxide semiconductor may be combined as appropriate. In addition, any one of the first to third oxide semiconductor films 199a to 199c has a structure other than that of the first to third oxide semiconductor films 199a to 199c. When an crystalline oxide semiconductor is used, the internal stress and external stress of the oxide semiconductor film are alleviated, Variation in transistor characteristics is reduced, and the transistors are less susceptible to deterioration over time and reliability tests. This can reduce the amount of variation in threshold voltage.

[0224] At least the second oxide semiconductor film 199b which can be a channel formation region is formed of CAAC In addition, the oxide semiconductor film on the back channel side is preferably an oxide semiconductor film having a thickness of 1000 nm or less. The third oxide semiconductor film 199c is amorphous or CAAC-OS. By adopting such a structure, it is possible to prevent deterioration of the transistor over time and the deterioration of the transistor due to reliability tests. The amount of variation in threshold voltage can be reduced.

[0225] Note that the structure described in this embodiment mode may be used in appropriate combination with structures described in other embodiments. You can be there.

[0226] (Fourth embodiment) A semiconductor device having a display function using the transistor and the capacitor shown as examples in the above embodiments In addition, a driving device including a transistor can be manufactured. Part or all of the circuitry is integrated onto the same substrate as the pixel section to form a system-on-panel. In this embodiment, the transistors exemplified in the above embodiments can be used. An example of the display device will be described with reference to FIGS. 13 to 15. Note that FIG. 14 shows the same display device as FIG. 3(B) is a cross-sectional view showing the cross-sectional structure of the portion indicated by the dashed line MN in FIG. 4, only a part of the structure of the pixel section is shown.

[0227] In FIG. 13A, a pixel portion 902 provided on a first substrate 901 is surrounded by a A sealant 905 is provided, and the substrate is sealed with a second substrate 906. 9, the area surrounded by the sealing material 905 on the first substrate 901 is different from the area surrounded by the sealing material 905 on the first substrate 901. In the region, a signal line driver formed of a single crystal semiconductor or a polycrystalline semiconductor on a separately prepared substrate is 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 C(Flexible printed circuit)918a, FPC918b? It is supplied by

[0228] In FIG. 13B and FIG. 13C, a pixel portion 902 provided on a first substrate 901 A sealant 905 is provided so as to surround 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, a sealing material 905, and a second substrate 906. The display element is sealed by the second substrate 906. In C), the area surrounded by the sealing material 905 on the first substrate 901 is different. A signal formed of a single crystal semiconductor or a polycrystalline semiconductor on a separately prepared substrate is 13B and 13C, the signal line Various signals and signals given to the driver circuit 903, the scanning line driver circuit 904, or the pixel portion 902 The potential is supplied from FPC918.

[0229] In addition, in FIGS. 13B and 13C, a signal line driver circuit 903 is separately formed. Although an example in which the scanning line driver is mounted on the first substrate 901 is shown, the present invention is not limited to this configuration. Alternatively, a driving circuit may be formed separately and mounted, or a part of a signal line driving circuit or a scanning line driving circuit may be mounted. Only a part of it may be formed separately and mounted.

[0230] The method of connecting the separately formed drive circuit is not particularly limited, and may be ip On Glass) method, wire bonding method, or TCP (Tape Car The COG method can be used. This is an example in which a twisted signal line driver circuit 903 and a scanning line driver circuit 904 are mounted. 13C is an example of mounting a signal line driver circuit 903 by the COG method, and FIG. 13C is an example of mounting a signal line driver circuit 903 by the TCP method. This is an example in which the signal line driver circuit 903 is implemented by the above.

[0231] The display device also includes a panel in which a display element is sealed, and a controller for the panel. and modules in which ICs, etc., including the above are mounted.

[0232] In this specification, the term "display device" refers to an image display device, a display device, or a light source. (including lighting devices). Also, connectors such as FPC or TCP are attached. a module with a printed wiring board at the end of the TCP, or a display element All modules with ICs (integrated circuits) directly mounted on the child by the COG method are included in the display device category. It shall be.

[0233] In addition, the pixel portion and the scanning line driver circuit provided on the first substrate have a plurality of transistors. The transistor described in the above embodiment can be applied to this.

[0234] 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. This category includes elements whose brightness is controlled by the light source, specifically inorganic EL (Electroluminescent) Luminescence elements, organic EL elements, etc. Also, electronic ink, etc. A display medium whose contrast changes electrically can also be used. 1 is a cross-sectional view of a liquid crystal display device using a liquid crystal element as a display element.

[0235] The liquid crystal display device shown in FIG. 14 is a vertical electric field type liquid crystal display device, but a horizontal electric field type liquid crystal display device may be used. The liquid crystal display device shown in FIG. The connection terminal electrode 915 and the terminal electrode 916 are F The terminals of the PC 918 are electrically connected via the anisotropic conductive material 919 .

[0236] The connection terminal electrode 915 is formed from the same conductive film as the first electrode 930, and the terminal electrode 916 is , the same conductive film as the source electrode and drain electrode of the transistor 910 and the transistor 911 It is formed by.

[0237] The pixel portion 902 and the scanning line driver circuit 904 provided on the first substrate 901 are A transistor 910 included in a pixel portion 902 and a scanning line driving circuit The transistor 910 and the transistor 911 included in the circuit 904 are illustrated. The insulating film 129, the insulating film 131, and the insulating film 132 shown in Embodiment 1 are formed over the transistor 911. An insulating film 924 corresponding to the insulating film 2 is provided. It is an insulating film.

[0238] A light-transmitting electrode 928 is formed on the insulating film 923 and is connected to a capacitor wiring 929. A gate insulating film 922 is formed on the electrode 928 and the capacitance wiring 929. The oxide semiconductor film 927 is formed on the transistor 2. 910 is connected to the drain electrode.

[0239] In this embodiment, the transistors 910 and 911 are the same as those in the above embodiment. The transistor shown in FIG. 1 can be applied. A capacitor 926 is formed using the oxide semiconductor film 927. The transistor 910 is formed from the same conductive film as the gate electrode of the transistor 911. Here, the capacitor 926 has a structure similar to that of the capacitor 105 described in Embodiment 1. Although shown using a capacitor, other capacitive elements may be used.

[0240] In addition, the oxide semiconductor film of the transistor 911 for the driver circuit is formed over the insulating film 924. In this example, a conductive film 917 is provided in a position overlapping with the channel forming region. In this embodiment, the conductive film 917 is formed using the same conductive film as the first electrode 930. By placing it in a position that overlaps with the channel formation region of the nitride semiconductor film, The amount of fluctuation in the threshold voltage of the transistor 911 can be further reduced. The potential of the conductive film 917 may be the same as or different from the gate electrode of the transistor 911. For example, the potential of the conductive film 917 may be GND, 0 V, or in a floating state. The conductive film 917 may function as a second gate electrode (back gate electrode). In addition, by controlling the potential of the conductive film 917, the threshold voltage of the transistor 911 can be controlled. It is possible to control the voltage to a low value.

[0241] The conductive film 917 also has the function of blocking an external electric field. (especially electrostatic shielding against static electricity) The shielding function of the conductive film 917 prevents the device from being affected by external electric fields such as static electricity. It is possible to prevent the electrical characteristics of the transistor from fluctuating. In the figure, the transistors included in the scanning line driver circuit are shown, but the transistors included in the signal line driver circuit are shown. The transistor 911 is also formed of an oxide semiconductor layer over the insulating film 924. The structure may be such that a conductive film is provided at a position overlapping the channel forming region of the film.

[0242] The transistor 910 provided in the pixel portion 902 is electrically connected to the display element, and The display element is not particularly limited as long as it can display, and various display elements can be used. You can be there.

[0243] The liquid crystal element 913, which is a display element, is made up of a first electrode 930, a second electrode 931, and a liquid crystal layer 9 908. Insulating films 932 functioning as alignment films are provided to sandwich the liquid crystal layer 908. An insulating film 933 is provided. The second electrode 931 is provided on the second substrate 906 side. The first electrode 930 and the second electrode 931 are configured to overlap with each other via the liquid crystal layer 908. There are.

[0244] A first electrode and a second electrode (such as a pixel electrode, a common electrode, and a counter electrode) that apply a voltage to the display element In the case of a photodiode (also called a photodiode), the direction of the extracted light, the location of the electrodes, and the pattern of the electrodes are all important factors. The transparency and reflectivity can be selected depending on the structure.

[0245] The first electrode 930 and the second electrode 931 are made of indium oxide containing tungsten oxide, Indium zinc oxide with tungsten oxide, indium oxide with titanium oxide, acid Indium tin oxide containing titanium dioxide, indium tin oxide (hereinafter referred to as ITO), Translucent conductive materials such as indium zinc oxide and indium tin oxide doped with silicon oxide Conductive materials can be used.

[0246] The first electrode 930 and the second electrode 931 are made of tungsten (W), molybdenum (M o), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb) , Tantalum (Ta), Chromium (Cr), Cobalt (Co), Nickel (Ni), Titanium ( Metals such as Ti), platinum (Pt), aluminum (Al), copper (Cu), and silver (Ag), can be formed using one or more of the alloys or metal nitrides thereof. Cut.

[0247] The spacer 935 is a columnar spacer obtained by selectively etching an insulating film. and 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.

[0248] When liquid crystal elements are used as display elements, thermotropic liquid crystals, low molecular weight liquid crystals, polymer liquid crystals, etc. The liquid crystals that can be used include polymer dispersed liquid crystals, ferroelectric liquid crystals, and antiferroelectric liquid crystals. Depending on the conditions, the liquid crystal material can be in a cholesteric phase, a smectic phase, a cubic phase, or a chiral phase. It shows nematic phase, isotropic phase, etc.

[0249] Alternatively, a liquid crystal that exhibits a blue phase without using an alignment film may be used. The blue phase is one of the liquid crystal phases. When the temperature of cholesteric liquid crystal is increased, the phase immediately transitions from the cholesteric phase to the isotropic phase. The blue phase appears only in a narrow temperature range, so the temperature range needs to be improved. To achieve this, a liquid crystal composition containing a chiral agent is used in the liquid crystal layer.

[0250] The first substrate 901 and the second substrate 906 are fixed together by a sealing material 925. The sealing material 925 can be an organic resin such as a thermosetting resin or a photosetting resin. The sealing material 925 is in contact with the insulating film 924. The sealing material 925 is the same as the sealing material shown in FIG. Equivalent to material 905.

[0251] In addition, in liquid crystal display devices, black matrices (light-shielding films), polarizing members, phase difference members, Optical members (optical substrates) such as anti-reflection members are provided as appropriate. Circularly polarized light from a differential substrate may also be used. may also be used.

[0252] In addition, since transistors are easily damaged by static electricity, a protection circuit for protecting the drive circuit is required. It is preferable that the protection circuit is configured using a non-linear element.

[0253] 15, in the liquid crystal display device shown in FIG. 14, the second electrode 93 provided on the substrate 906 9 shows an example in which a common connection portion (pad portion) for electrically connecting to the substrate 901 is formed on the substrate 901. vinegar.

[0254] The common connection portion is arranged at a position overlapping the sealing material for bonding the substrate 901 and the substrate 906. The sealing material is electrically connected to the second electrode 931 via conductive particles contained in the sealing material. Alternatively, a common connection part is provided in a place that does not overlap with the sealing material (excluding the pixel part), and the common connection 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 the

[0255] FIG. 15(A) is a cross-sectional view of the common connection portion, which corresponds to IJ in the top view shown in FIG. 15(B). do.

[0256] The common potential line 975 is provided on the gate insulating film 922 and is connected to the transistor shown in FIG. The electrode is made of the same material and in the same process as the source electrode 971 or the drain electrode 973 of the capacitor 910. can be.

[0257] The common potential line 975 is covered with an insulating film 924. The openings are located at positions overlapping the source of the transistor 910. A contact that connects one of the electrode 971 or the drain electrode 973 to the first electrode 930 It is made using the same process as a hole.

[0258] In addition, the common potential line 975 and the common electrode 977 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 using the same process.

[0259] In this way, the common connection portion is fabricated by the same fabrication process as the switching element of the pixel portion 902. It is possible.

[0260] The common electrode 977 is an electrode that comes into contact with the conductive particles contained in the sealing material, and is Electrical connection is made with the second electrode 931 .

[0261] 15C, the common potential line 985 is connected to the gate voltage of the transistor 910. It may be made of the same material and in the same process as the electrodes.

[0262] In the common connection portion shown in FIG. 15(C), the common potential line 985 is connected to the gate insulating film 922 and The gate insulating film 922 and the insulating film 924 are disposed below the common potential line 9 The openings are located at positions overlapping with the source voltage of the transistor 910. A contact hole connecting one of the electrode 971 or the drain electrode 973 to the first electrode 930 is provided. After etching the insulating film 924 in the same process as the gate insulating film 922, the gate insulating film 922 is selectively It is formed by etching.

[0263] Furthermore, 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 using the same process.

[0264] As described above, by using the transistor and the capacitor described in the above embodiment, the aperture ratio It is possible to provide a semiconductor device having a capacitive element with increased charge capacity while improving the capacitance. Moreover, by increasing the aperture ratio, a semiconductor device with good display quality can be obtained.

[0265] In addition, oxygen vacancies are reduced in the oxide semiconductor film that is the semiconductor film of the transistor, and hydrogen, nitrogen, and the like are released. Since the amount of impurities such as SiO 2 is reduced, the semiconductor device according to one embodiment of the present invention has good electrical conductivity. This results in a semiconductor device with thermal conductivity.

[0266] Note that the structure described in this embodiment mode may be used in appropriate combination with structures described in other embodiments. You can be there.

[0267] (Embodiment 5) The semiconductor device of one embodiment of the present invention can be applied to various electronic devices (including gaming machines). The electronic equipment includes a television device (television or television receiver) ), computer monitors, digital cameras, digital video cameras, Digital photo frames, mobile phones, portable game consoles, personal digital assistants, sound reproduction devices, These electronic devices include gaming machines (pachinko machines, slot machines, etc.) and game cabinets. An example is shown in Figure 16.

[0268] 16A shows a table 9000 having a display section. A display unit 9003 is incorporated in a housing 9001, and images are displayed on the display unit 9003. It is possible to support the housing 9001 with four legs 9002. The housing 9001 also has a power cord 9005 for power supply.

[0269] 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 unit 9003 can be improved. The reliability of 3 can be improved.

[0270] The display unit 9003 has a touch input function, and the display unit 9003 of the table 9000 By touching the displayed display button 9004 with a finger or the like, the screen can be operated or information can be input. It can also communicate with other home appliances or control them, improving the quality of images. It may also be used as a control device to control other home appliances by surface manipulation. If a semiconductor device having a sensor function is used, the display portion 9003 can have a touch input function. It is possible.

[0271] In addition, the screen of the display unit 9003 can be vertically fixed to the floor by a hinge provided in the housing 9001. It can also be set upright and used as a television set. If you install a large screen television, the free space will be narrow, but it is possible to install it on a table. If the display unit is built in, the space in the room can be used more effectively.

[0272] FIG. 16(B) shows a television device 9100. The television device 9100 A display unit 9103 is incorporated in the housing 9101, and images are displayed on the display unit 9103. In this example, the housing 9101 is supported by a stand 9105. The configuration is shown.

[0273] 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 the remote control operation device 9110. The channel and volume can be controlled by the 9109, and the information displayed on the display 9103 is In addition, the remote control unit 9110 can be used to operate the video. A display unit 9107 for displaying information output from 9110 may be provided.

[0274] The television device 9100 shown in FIG. 16(B) includes a receiver, a modem, and the like. The broadcasting 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 (sender to receiver) or two-way (sender to receiver, or receiver to receiver) It is also possible to carry out information communication.

[0275] The semiconductor device described in any of the above embodiments can be used for the display portions 9103 and 9107. Therefore, the display quality of the television device can be improved, and reliability can be improved. can be improved.

[0276] FIG. 16C shows a computer, which includes a main body 9201, a housing 9202, a display portion 9203, and a keyboard. keyboard 9204, external connection port 9205, pointing device 9206, etc. nothing.

[0277] 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 can be improved, and the reliability can be improved. This can be done.

[0278] Figures 17(A) and 17(B) show a foldable tablet terminal. 9631a is in an open state, and the tablet terminal includes a housing 9630, a display unit 9631a, and a display unit 9631b, display mode switch 9034, power switch 9035, power saving mode It has a mode changeover switch 9036, a fastener 9033, and an operation switch 9038.

[0279] The semiconductor device described in any of the above embodiments has a display portion 9631a and a display portion 9631b. Therefore, it is possible to improve the display quality of tablet devices. , the reliability can be improved.

[0280] A part of the display unit 9631a can be used as a touch panel area 9632a. By touching the operation keys 9638, data can be input. In 1a, for example, half of the area has a display function only, and the other half The display unit 963 has a touch panel function, but is not limited to this. The entire area of ​​the display unit 96 may have a touch panel function. The entire surface of 31a is displayed as a keyboard button to serve as a touch panel, and the display part 9631b is displayed. It can be used as a screen.

[0281] In addition, in the display unit 9631b, as in the display unit 9631a, a part of the display unit 9631b The area 9632b of the touch panel can be used as the keyboard of the touch panel. By touching the area where the display switch button 9639 is displayed with your finger or a stylus, A keyboard can be displayed on the display portion 9631b.

[0282] In addition, touch panel area 9632a and touch panel area 9632b can be touched simultaneously. You can also input characters using the touchpad.

[0283] The display mode switch 9034 is used to change the display orientation, such as portrait or landscape. You can switch between black and white and color display. The Switch 9036 detects external light during use using a light sensor built into the tablet device. The tablet device can optimize the display brightness according to the amount of light in the room. In addition to sensors, other detection devices such as gyros and acceleration sensors that detect tilt are also included. It may be built-in.

[0284] FIG. 17A 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, and the display For example, one display panel may be capable of displaying images with higher resolution than the other. It may also be possible to use the following.

[0285] FIG. 17(B) shows the tablet terminal in a closed state, and the tablet terminal includes a housing 9630 and a solar cell 96 33 and a charge / discharge control circuit 9634. Note that in FIG. As an example of 4, a configuration having a battery 9635 and a DC-DC converter 9636 It shows.

[0286] In addition, the tablet device can be folded in half, so when not in use, the housing 9630 can be folded. Therefore, the display portions 9631a and 9631b can be protected, and thus the display portions 9631a and 9631b can be withstood. This makes it possible to provide a tablet terminal that is highly durable and reliable even from the perspective of long-term use.

[0287] In addition, the tablet terminals shown in Figs. 17(A) and 17(B) can store various information. Functions that display information (still images, videos, text images, etc.), calendars, dates, or times The function to display the information on the display, and the function to operate or edit the information displayed on the display. It has functions such as inputting characters, controlling processes using various software (programs), etc. It is possible.

[0288] The solar cell 9633 attached to the surface of the tablet terminal supplies power to the touch panel, The solar cell 9633 can be supplied to a display unit, a video signal processor, or the like. The battery 9635 can be efficiently charged by providing a battery charger on one or both sides of the housing 9630. The battery 9635 may be a lithium-ion battery. The use of such a device has the advantage of enabling miniaturization.

[0289] The configuration and operation of the charge / discharge control circuit 9634 shown in FIG. 17(B) will be described with reference to FIG. ) shows a block diagram and explains. In FIG. 17(C), a solar cell 9633, a battery 96 35, DC-DC converter 9636, converter 9637, switches SW1 to SW3, The display unit 9631 is shown, along with the battery 9635 and the DC-DC converter 9636. The converter 9637 and the switches SW1 to SW3 constitute a charge / discharge control circuit shown in FIG. This corresponds to road 9634.

[0290] First, an example of operation when power is generated by the solar cell 9633 using external light will be described. The power generated by the solar cell is converted to DC voltage to charge the battery 9635. The voltage is increased or decreased by the DC converter 9636. When power is supplied from the solar cell 9633, switch SW1 is turned on and the converter The voltage is increased or decreased by 9637 to the voltage required for the display unit 9631. When not displaying on the 9631, turn SW1 off and SW2 on to charge the battery. -9635 can be configured to charge.

[0291] The solar cell 9633 is shown as an example of a power generating means, but is not particularly limited thereto. Other power generation methods such as piezoelectric elements and thermoelectric conversion elements (Peltier elements) For example, the battery 9635 may be charged wirelessly (contactlessly). A wireless power transmission module that receives and charges, or a structure that combines other charging methods It may also be composed.

[0292] Note that the structure described in this embodiment mode may be used in appropriate combination with structures described in other embodiments. You can be there. [Explanation of symbols]

[0293] 100 pixel unit 101 pixels 102 Circuit Board 103 Transistor 104 Scanning line driving circuit 105 Capacitive element 106 Signal line driver circuit 107 scan lines 108 Liquid crystal element 109 Signal Line 111 Semiconductor film 113 Conductive film 115 Capacitance Line 117 Aperture 119 Semiconductor Film 121 pixel electrode 122 electrodes 127 Gate insulating film 128 insulating film 129 insulating film 130 insulating film 131 insulating film 132 insulating film 133 Insulating Film 135 Conductive film 150 boards 151 pixels 152 Light-shielding film 153 Transistor 154 Counter electrode 156 Insulating film 158 insulating film 160 liquid crystal layer 161 pixels 165 Capacitor 167 Capacitance Line 182 Channel protection film 183 Transistor 190 transistors 200 transistors 901 Circuit Board 902 Pixel section 903 Signal line driver circuit 904 Scanning line driver circuit 905 Sealing material 906 Circuit Board 908 Liquid crystal layer 910 Transistor 911 Transistor 913 Liquid crystal element 915 Connection terminal electrode 916 Terminal electrode 917 Conductive film 918 FPC 919 Anisotropic Conductive Materials 922 Gate insulating film 923 Insulating Film 924 insulating film 925 sealing material 926 Capacitor 927 Oxide semiconductor film 928 Electrode 929 Capacitance wiring 930 electrode 931 Electrode 932 Insulating film 933 Insulating Film 935 Spacer 971 Source electrode 973 Drain electrode 975 Common potential line 977 Common electrode 985 Common potential line 987 Common electrode 9000 tables 9001 Case 9002 Legs 9003 Display section 9004 Display button 9005 Power Cord 9033 Tools 9034 Switch 9035 Power Switch 9036 Switch 9038 Operation switch 9100 Television equipment 9101 Housing 9103 Display section 9105 Stand 9107 Display section 9109 Operation key 9110 Remote control device 9201 Main Unit 9202 Housing 9203 Display section 9204 keyboard 9205 External connection port 9206 Pointing Device 9630 chassis 9631 Display section 9633 Solar Cells 9634 Charge / Discharge Control Circuit 9635 Battery 9636 DC / DC Converter 9637 Converter 9638 Operation Key 9639 Button 103_1 Transistor 103_2 Transistor 107_1 scan line 107_2 scan line 107a Gate electrode 109a Source electrode 111_1 Semiconductor film 111_2 Semiconductor film 113_1 Conductive film 113_2 Conductive film 113a Drain electrode 117_1 Aperture 117_2 Aperture 119_1 Semiconductor film 119_2 Semiconductor film 121_1 Pixel electrode 121_2 Pixel electrode 122_1 Electrode 122_2 Electrode 127a Gate insulating film 127b Gate insulating film 199a Oxide semiconductor film 199b Oxide semiconductor film 199c Oxide semiconductor film 401_1 pixel 401_2 pixels 405_1 Capacitor element 405_2 Capacitor element 918a FPC 918b FPC

Claims

1. A display device having a transistor, a capacitor, and a pixel electrode, a first oxide semiconductor layer, a second oxide semiconductor layer, a first conductive layer, a second conductive layer, a third conductive layer, a first insulating layer, and a second insulating layer; the first oxide semiconductor layer has a channel formation region of the transistor, the second oxide semiconductor layer functions as an electrode of the capacitor; the first conductive layer functions as a source electrode or a drain electrode of the transistor; the first conductive layer has a region in contact with a top surface of the first oxide semiconductor layer and a region in contact with a side surface of the first oxide semiconductor layer; the first insulating layer has a region in contact with an upper surface of the first oxide semiconductor layer, a region in contact with an upper surface of the second oxide semiconductor layer, a region in contact with an upper surface of the first conductive layer, and a region in contact with a side surface of the first conductive layer; the second conductive layer functions as the pixel electrode; the second conductive layer has a region located above the first insulating layer and a region in contact with the first conductive layer, the second insulating layer functions as a gate insulating layer of the transistor; the second insulating layer has a region located below the second oxide semiconductor layer, the third conductive layer has a region located below the second insulating layer; the second oxide semiconductor layer has a first region overlapping with the third conductive layer with the second insulating layer interposed therebetween; the first region has a second region overlapping with the second conductive layer via a region where the first insulating layer is in contact with an upper surface of the second oxide semiconductor layer.

2. In claim 1, the first oxide semiconductor layer contains indium oxide; The display device, wherein the second oxide semiconductor layer contains indium oxide.

Images