Liquid crystal display device

Abstract

To provide a manufacturing method capable of achieving cost reduction in a semiconductor device with a capacitative element which has a high opening ratio and an increase a charge capacity, or to provide a manufacturing method capable of achieving cost reduction in a semiconductor device which can reduce power consumption.SOLUTION: In a method for concurrently manufacturing a transistor and a capacitative element, a channel protective film and a metal oxide film with a channel region included in the transistor, and one electrode of the capacitative element are formed according to a process using a multi-level gradation photomask.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a semiconductor device having, for example, a transistor. [Background technology]

[0002] It is used in many flat panel displays, such as liquid crystal displays and light-emitting displays. The transistors used are made of amorphous silicon and single-crystal silicon formed on a glass substrate. It is made of silicon semiconductor such as silicon or polycrystalline silicon. Transistors using semiconductors are also used in integrated circuits (ICs).

[0003] In recent years, metal oxides that exhibit semiconductor properties have been used in transistors instead of silicon semiconductors. In this specification, metal oxides that exhibit semiconductor properties are referred to as oxides. We will call it a semiconductor.

[0004] For example, a transistor using zinc oxide or an In-Ga-Zn oxide as an oxide semiconductor may be used. A transistor is fabricated and used as a switching element for a pixel of a display device. A technique for this has been disclosed (see Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-123861 Summary of the Invention [Problem to be solved by the invention]

[0006] Display devices on the market tend to be larger, with screen sizes of 40 inches or more diagonally. Furthermore, development is underway with a view to screen sizes of 120 inches or more diagonally. For this reason, glass substrates used in display devices are becoming larger in area than the 8th generation. It's progressing.

[0007] As the area of ​​glass substrates increases, the exposure equipment used in the manufacturing process of display devices is becoming increasingly large. The photomasks used are becoming larger, and the cost of the photomasks is becoming an issue. Since 10th generation photomasks are expensive, costing over 100 million yen each, we are trying to reduce the number of photomasks. There is a need to develop a manufacturing process that reduces this.

[0008] On the other hand, in a liquid crystal display device, which is an example of a display device, the charge capacity of a capacitive element is increased. The more the liquid crystal molecules in the liquid crystal element can be kept aligned in a constant manner when an electric field is applied, the more stable the alignment becomes. In a display device that displays a still image, the period can be extended. What can be achieved is to reduce the number of times image data is rewritten, which would reduce power consumption. Meru.

[0009] Therefore, in order to increase the charge capacity of the capacitance element, the area occupied by the capacitance element is increased. Specifically, there is a means to increase the area where the pair of electrodes overlap. Therefore, in the above display device, in order to increase the area where the pair of electrodes overlap, If the area of ​​the conductive film is increased, the aperture ratio of the pixel is reduced, and the display quality of the image is deteriorated. .

[0010] One embodiment of the present invention provides a capacitor element that has a high aperture ratio and can increase charge capacitance. The object is to provide a manufacturing method capable of reducing costs in a semiconductor device having Another embodiment of the present invention is a semiconductor device capable of reducing power consumption. Therefore, one object is to provide a manufacturing method that can reduce costs. [Means for solving the problem]

[0011] One embodiment of the present invention is a method for manufacturing a channel protective transistor by using a multi-tone phototransistor. A metal oxide film having a channel region and a channel protection film are formed by a process using a mask. Another embodiment of the present invention is a method for simultaneously forming a transistor and a capacitor. In this method, a multi-tone photomask is used to form a transistor. a metal oxide film having a channel region and a channel protection film; one electrode of a capacitor element; The present invention is characterized by forming:

[0012] One embodiment of the present invention is to form a gate electrode and a gate insulating film on an insulating surface, a first metal oxide film and a first insulating film are formed on the first insulating film; a first mask having an area having a thickness greater than the first thickness and an area having a second thickness greater than the first thickness; forming a second mask having the same thickness as the first mask; and The first insulating film and the first metal oxide film are etched using the etching gas. Then, the second and third insulating films, the second metal oxide film, and the third metal oxide film are formed. After processing the first mask to form a third mask and removing the second mask, The second insulating film is etched using the third mask to form a fourth insulating film on the second metal oxide film. The insulating film is formed and the third insulating film on the third metal oxide film is removed. a nitride insulating film on the metal oxide film, the third metal oxide film, the fourth insulating film, and the gate insulating film; A fifth insulating film is formed by etching a part of the fifth insulating film. After forming an opening in the film, a pair of electrodes contacting the second metal oxide film and a third metal oxide film are formed. Next, a wiring is formed on the fifth insulating film, which is connected to one of the pair of electrodes, and and forming a light-transmitting conductive film that overlaps a part of the third metal oxide film. This is the manufacturing method.

[0013] One embodiment of the present invention is to form a gate electrode and a gate insulating film on an insulating surface, a first metal oxide film and a first insulating film are formed on the first insulating film; a first mask having an area having a thickness greater than the first thickness and an area having a second thickness greater than the first thickness; A second mask having the same thickness as the first mask is formed. The first insulating film and the first metal oxide film are respectively etched using a mask to form a second insulating film. The first insulating film, the third insulating film, the second metal oxide film, and the third metal oxide film are formed. Next, the first mask is processed to form a third mask and remove the second mask. After the removal, the second insulating film is etched using a third mask to form a second metal oxide film. A fourth insulating film is formed on the third metal oxide film, and the third insulating film on the third metal oxide film is removed. A pair of electrodes contacting the second metal oxide film and a wiring contacting the third metal oxide film are formed. Then, a nitride insulating film is formed on the pair of electrodes, the fourth insulating film, the third metal oxide film, and the wiring. Next, a part of the fifth insulating film is etched to form the fifth insulating film. After forming an opening in the insulating film, a portion of the third metal oxide film is connected to one of the pair of electrodes. The present invention relates to a method for manufacturing a semiconductor device, in which a light-transmitting conductive film is formed to overlap with a portion.

[0014] After the fifth insulating film is formed, openings are formed in the gate insulating film and the fifth insulating film. At the same time, a part of the gate electrode is exposed, a light-transmitting conductive film is formed, and the gate electrode is A conductive film may be formed that is connected to the port electrode and overlaps the second metal oxide film.

[0015] It also functions as a gate electrode, a gate insulating film, a second metal oxide film, and a channel protection film. The fourth insulating film and the pair of electrodes constitute a transistor. The capacitor element is formed using the insulating film, the fifth insulating film, and the light-transmitting conductive film.

[0016] The third metal oxide film is in contact with the fifth insulating film made of a nitride insulating film. The third metal oxide film has conductivity and functions as one electrode of the capacitor element.

[0017] The second metal oxide film and the third metal oxide film have different hydrogen concentrations. The first metal oxide film has a higher hydrogen concentration than the second metal oxide film.

[0018] The first metal oxide film, the second metal oxide film, and the third metal oxide film are light-transmitting. The first metal oxide film, the second metal oxide film, and the third metal oxide film have The first metal oxide film and the second metal oxide film have at least one of In, Ga, and Zn. The first metal oxide film and the third metal oxide film are composed of the same metal element.

[0019] Further, the gate insulating film has a region in contact with the second metal oxide film and the third metal oxide film. The region is formed of an oxide insulating film. Also, a fourth insulating film is formed on the second metal oxide film. The contact region is formed of an oxide insulating film.

[0020] A part of the gate insulating film is formed of a nitride insulating film, and the nitride insulating film and the fifth insulating film are The insulating films are in contact with each other.

[0021] The fourth insulating film includes an oxide insulating film from which part of oxygen is released by heating. [Effects of the Invention]

[0022] According to one embodiment of the present invention, a capacitor element having a high aperture ratio and capable of increasing charge capacity can be provided. In the method for manufacturing a semiconductor device having a semiconductor device, the cost can be reduced. In a method for manufacturing a semiconductor device that can reduce the number of wirings, costs can be reduced. [Brief explanation of the drawings]

[0023] [Figure 1] 1A and 1B are a block diagram and a circuit diagram illustrating one embodiment of a semiconductor device. [Figure 2] FIG. 1 is a top view illustrating one embodiment of a transistor. [Figure 3] 1A to 1C are cross-sectional views illustrating one embodiment of a method for manufacturing a transistor. [Figure 4] 1A to 1C are cross-sectional views illustrating one embodiment of a method for manufacturing a transistor. [Figure 5] 1A to 1C are cross-sectional views illustrating one embodiment of a method for manufacturing a transistor. [Figure 6] FIG. 1 is a top view illustrating one embodiment of a transistor. [Figure 7] 1A to 1C are cross-sectional views illustrating one embodiment of a method for manufacturing a transistor. [Figure 8] 1A to 1C are cross-sectional views illustrating one embodiment of a method for manufacturing a transistor. [Figure 9] FIG. 1 is a cross-sectional view illustrating one embodiment of a transistor. [Figure 10] FIG. 1 is a top view illustrating one embodiment of a transistor. [Figure 11]FIG. 1 is a cross-sectional view illustrating one embodiment of a transistor. [Figure 12] FIG. 1 is a diagram illustrating an electronic device. [Figure 13] FIG. 10 is a diagram illustrating the temperature dependence of resistivity. DETAILED DESCRIPTION OF THE INVENTION

[0024] 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 the embodiments and methods thereof may be modified without departing from the spirit and scope of the present invention. It will be readily apparent to those skilled in the art that various modifications may be made to the design and details of the present invention. However, the present invention should not be construed as being limited to the description of the following embodiments and examples. In the embodiments and examples described below, the same parts or parts having similar functions In the case of parts, the same symbols or the same hatch patterns are used in common among different drawings, and the repetition The explanation of repetition will be omitted.

[0025] In each figure described in this specification, the size of each component, the thickness of the film, or the area is The figures may be exaggerated for clarity and are not necessarily limited to that scale. stomach.

[0026] In addition, terms such as first, second, and third used in this specification are used interchangeably to avoid confusion of components. It is not intended to limit the number of items. The terms "second" or "third" can be used interchangeably to explain the present invention.

[0027] The functions of the "source" and "drain" are also different when the direction of the current changes during circuit operation. For this reason, in this specification, the terms "sauce" and "dressing" are used interchangeably. The terms "in" and "in" may be used interchangeably.

[0028] Voltage refers to the potential difference between two points, and potential refers to the electrostatic field at a certain point. This refers to the electrostatic energy (electrical potential energy) of a unit charge in a particle. However, in general, the potential difference between the potential at a certain point and a reference potential (for example, ground potential) This is simply called potential or voltage, and potential and voltage are often used synonymously. Therefore, in this specification, unless otherwise specified, the term "potential" may be read as "voltage." , voltage may be read as potential.

[0029] In this specification, when an etching step is performed after a photolithography step, The mask formed in the photolithography process is removed.

[0030] (Embodiment 1) In this embodiment, a capacitor element having a high aperture ratio and capable of increasing the charge capacity is provided. The object is to provide a manufacturing method capable of reducing costs in a semiconductor device having Another embodiment of the present invention is a semiconductor device capable of reducing power consumption. Therefore, one object is to provide a manufacturing method that can reduce costs.

[0031] In addition, in the metal oxide, an oxide semiconductor, which is a metal oxide having semiconductor properties, is used. In the case of a transistor, oxygen is an example of a defect that can lead to poor electrical characteristics of the transistor. For example, a transistor using an oxide semiconductor film containing oxygen vacancies The threshold voltage of the transistor tends to fluctuate in the negative direction, and the transistor tends to have normally-on characteristics. This is because oxygen vacancies in the oxide semiconductor film generate charges, which lower the resistance. If a transistor has normally-on characteristics, malfunctions are likely to occur during operation. This can cause various problems, such as the power consumption during non-operation being high. The electrical characteristics of transistors, typically the amount of change in threshold voltage, are measured by the application of thermal and stress tests. There is a growing problem.

[0032] In addition to oxygen deficiency, impurities such as silicon and carbon, which are constituent elements of the insulating film, also cause damage to the transistor. Therefore, the impurities are mixed into the oxide semiconductor film, which causes poor electrical characteristics of the transistor. As a result, the resistance of the oxide semiconductor film is reduced, and the oxide semiconductor film is susceptible to deterioration over time and stress testing. This leads to a problem of an increase in the amount of fluctuation in the electrical characteristics of the transistor, typically the threshold voltage. There is.

[0033] In this embodiment, in addition to the problem to be solved by the present invention, In a semiconductor device including a transistor, An object is to reduce oxygen vacancies and the impurity concentration in the oxide semiconductor film.

[0034] In this embodiment mode, as a method for solving one of the above problems, a manufacturing method of a semiconductor device will be described. In this embodiment, a process using a multi-tone photomask is performed. A metal oxide film having a channel region and a channel protection film are formed. .

[0035] 1A shows an example of a semiconductor device. The semiconductor device shown in FIG. 1A includes a pixel portion 11 , a scanning line driving circuit 14, and a signal line driving circuit 16 are arranged parallel or approximately parallel to each other. The scanning lines 17 are parallel to each other and the potential of each of the scanning lines 17 is controlled by the scanning line driving circuit 14. n signal lines arranged in parallel or substantially parallel to each other, and the potentials of which are controlled by a signal line driving circuit 16. 19. Furthermore, the pixel section 11 has a plurality of pixels 13 arranged in a matrix. In addition, the capacitor lines 15 are arranged parallel or approximately parallel to each other along the signal lines 19. The capacitance lines 15 are arranged parallel or approximately parallel to each other along the scanning lines 17. The scanning line driving circuit 14 and the signal line driving circuit 16 may be collectively referred to as a driving circuit section. This is sometimes said.

[0036] Each scanning line 17 corresponds to one of the pixels 13 arranged in m rows and n columns in the pixel section 11. Each signal line 19 is electrically connected to n pixels 13 arranged in m rows and n Among the pixels 13 arranged in a column, m pixels 13 arranged in any one column are electrically connected. Both m and n are integers equal to or greater than 1. The capacitance lines 15 are arranged in m rows and n columns. Among the pixels 13 arranged in one row, the n pixels 13 are electrically connected to the n pixels 13 arranged in one row. The capacitance lines 15 are arranged parallel or approximately parallel to the signal lines 19. In this case, m pixels 13 arranged in m rows and n columns are arranged in any one of the columns. 13 is electrically connected to

[0037] 1B and 1C show circuitry that can be used for the pixel 13 of the display device shown in FIG. 1A. 1 shows an example of a road configuration.

[0038] The pixel 13 shown in FIG. 1B includes a liquid crystal element 21, a transistor 22, and a capacitor 25. , has.

[0039] The potential of one of the pair of electrodes of the liquid crystal element 21 is set appropriately according to the specifications of the pixel 13 . The alignment state of the liquid crystal element 21 is set by the written data. A common potential is applied to one of the pair of electrodes of the liquid crystal element 21 of each of the liquid crystal display devices 3. Alternatively, a different potential may be applied to one of the pair of electrodes of the liquid crystal element 21 for each pixel 13 in each row. May be given.

[0040] The liquid crystal element 21 controls the transmission or non-transmission of light by the optical modulation action of the liquid crystal. The optical modulation effect of the liquid crystal is achieved by the electric field applied to the liquid crystal (horizontal electric field, vertical electric field). The liquid crystal element 21 is controlled by a vertical electric field (including a diagonal electric field or an oblique electric field). , nematic liquid crystal, cholesteric liquid crystal, smectic liquid crystal, thermotropic liquid crystal, Examples include iotropic liquid crystal, ferroelectric liquid crystal, and antiferroelectric liquid crystal.

[0041] The display device having the liquid crystal element 21 can be driven in, for example, TN mode, VA mode, or the like. , ASM(Axially Symmetric Aligned Micro-cel l) mode, OCB (Optically Compensated Birefringence Gence mode, MVA mode, PVA (Patterned Vertical Alignment) mode, IPS mode, FFS mode, or TBA (Trans You can also use the (Verse Bend Alignment) mode. The present invention is not limited to the above, and various liquid crystal elements and driving methods thereof can be used.

[0042] Also, a liquid crystal composition containing a liquid crystal exhibiting a blue phase and a chiral agent The liquid crystal element may be configured by the following. The liquid crystal that exhibits the blue phase has a response speed of 1 msec or less. Since it is short and optically isotropic, alignment treatment is not required and viewing angle dependency is small.

[0043] In the configuration of the pixel 13 shown in FIG. 1B, the source electrode and the drain electrode of the transistor 22 One of the electrodes is electrically connected to the signal line 19, and the other is the other of the pair of electrodes of the liquid crystal element 21. The gate electrode of the transistor 22 is electrically connected to the scanning line 17. The transistor 22 is turned on or off to The transistor 22 has a function of controlling the writing of signal data. The transistor described in any of Embodiments 1 to 7 can be used.

[0044] In the configuration of the pixel 13 shown in FIG. 1B, one of the pair of electrodes of the capacitor 25 is connected to a potential The other end is electrically connected to the other of the pair of electrodes of the liquid crystal element 21. The potential value of the capacitance line 15 is set appropriately according to the specifications of the pixel 13. The capacitor element 25 functions as a storage capacitor for storing written data. do.

[0045] For example, in a display device having the pixel 13 shown in FIG. 1B, the scanning line driving circuit 14 drives each row The pixels 13 are selected in sequence, the transistors 22 are turned on, and the data of the data signal is written. Enter.

[0046] The pixel 13 into which the data has been written is in a holding state when the transistor 22 is turned off. By performing this process row by row, an image can be displayed.

[0047] The pixel 13 shown in FIG. 1C includes a transistor 33 that switches the display element. a transistor 22 for controlling driving of the pixel, a transistor 35, a capacitor element 25, and a light-emitting element 31.

[0048] An example of the light-emitting element 31 is a light-emitting element including an anode, a cathode, and an EL layer sandwiched between the anode and the cathode. An example of an EL layer is a device in which light emission (fluorescence) from singlet excitons occurs. a layer having a material capable of emitting light from triplet excitons (phosphorescence); Materials capable of emitting light from single excitons (fluorescence) and materials capable of emitting light from triplet excitons (phosphorescence) The layer may include a layer having a material.

[0049] One of the source electrode and the drain electrode of the transistor 33 is connected to a signal line to which a data signal is applied. The gate electrode of transistor 22 is electrically connected to gate signal line 19. is electrically connected to a scan line 17 to which a signal is applied.

[0050] The transistor 33 is turned on or off to transmit the data of the data signal. It has the function of controlling the writing of

[0051] One of the source and drain electrodes of the transistor 22 functions as an anode line. The other of the source electrode and the drain electrode of the transistor 22 is electrically connected to the wiring 37. , is electrically connected to one electrode of the light emitting element 31. Furthermore, the gate of the transistor 22 The electrode is the other of the source electrode and the drain electrode of the transistor 33 and one of the capacitor elements 25. The electrode is electrically connected to the other electrode.

[0052] The transistor 22 is turned on or off to allow current to flow to the light emitting element 31. It has the function of controlling the current flowing through it.

[0053] One of the source and drain electrodes of the transistor 35 is given a data reference potential. The other of the source electrode and the drain electrode of the transistor 35 is connected to a wiring 39 that is connected to a light-emitting element. It is electrically connected to one electrode of the element 31 and the other electrode of the capacitive element 25. The gate electrode of the transistor 35 is electrically connected to the scanning line 17 to which a gate signal is applied. can be.

[0054] The transistor 35 has a function of adjusting the current flowing through the light-emitting element 31. When the internal resistance of the light emitting element 31 increases due to deterioration of the light emitting element 31, the transistor 35 The current flowing through the wiring 39 to which one of the source electrode and the drain electrode of the By doing so, it is possible to correct the current flowing through the light emitting element 31. The potential can be set to 0V, for example.

[0055] One of the pair of electrodes of the capacitor 25 is connected to the source electrode and the drain electrode of the transistor 33. and the gate electrode of the transistor 22, and a pair of capacitors 25 The other electrode is connected to the other of the source electrode and drain electrode of the transistor 35 and the light emitting element 3 1 is electrically connected to one electrode of the

[0056] In the configuration of the pixel 13 shown in FIG. 1C, the capacitor element 25 stores the written data. It functions as a storage capacitor.

[0057] One of the pair of electrodes of the light emitting element 31 is the source electrode and the drain electrode of the transistor 35. the other end of the capacitor 25, and the other end of the source electrode and drain electrode of the transistor 22. The other of the pair of electrodes of the light emitting element 31 functions as a cathode. The wiring 41 is electrically connected to the wiring 41.

[0058] The light-emitting element 31 may be, for example, an organic electroluminescence element (also called an organic EL element). However, the light emitting element 31 is not limited to this, and An inorganic EL element made of organic materials may also be used.

[0059] A high power supply potential VDD is applied to one of the wiring 37 and the wiring 41, and a low power supply potential VDD is applied to the other. In the configuration shown in FIG. 1C, a high power supply potential VSS is applied to the wiring 37. VDD is applied to the wiring 41, and a low power supply potential VSS is applied to the wiring 42.

[0060] In the display device having the pixel 13 of FIG. 1C, the pixel 1 of each row is driven by the scanning line driving circuit 14. 3 are selected in sequence, and the transistor 22 is turned on to write the data of the data signal.

[0061] The pixel 13 into which the data has been written is in a holding state when the transistor 22 is turned off. Furthermore, since the transistor 22 is connected to the capacitance element 25, the written The data can be retained for a long time. The amount of current flowing between the drain electrode and the gate electrode is controlled, and the light emitting element 31 emits a light according to the amount of current flowing. By repeating this process row by row, an image can be displayed.

[0062] In this specification and the like, the term "display element," "display device having a display element," "light emitting element," "light emitting device," "light emitting element ... A light-emitting device, which is a device having a light-emitting element and a light-emitting element, can be used in various forms or in various Examples of a display element, a display device, a light-emitting element, or a light-emitting device include EL (electroluminescence) elements (EL elements containing organic and inorganic materials, organic EL elements, inorganic EL elements), transistors (transistors that emit light according to current), electrons Emission element, liquid crystal element, electronic ink, electrophoretic element, digital micromirror device (D MD), DMS (Digital Micro Shutter), etc., are made by electromagnetic action. Some have display media that change contrast, brightness, reflectance, transmittance, etc. An example of a display device using electron-emitting devices is an EL display. An example of such a display device is a field emission display (FED) or SE D-type flat panel display (SED: Surface-conduction Electro Display devices using liquid crystal elements include An example is a liquid crystal display (transmissive liquid crystal display, semi-transmissive liquid crystal display). , reflective LCD displays, direct-view LCD displays, projection LCD displays, etc. An example of a display device using electronic ink or electrophoretic elements is electronic paper. There is.

[0063] Next, a specific example of an element substrate of a liquid crystal display device using a liquid crystal element for the pixel 13 will be described. Here, a top view of the pixel 13 shown in FIG. 1(B) is shown in FIG.

[0064] In FIG. 2, the conductive film 103 functioning as a scanning line is oriented in a direction substantially perpendicular to the signal line ( The conductive film 117a that functions as a signal line is provided so as to extend in the horizontal direction. The conductive film is provided so as to extend in a direction substantially perpendicular to the capacitor line (the vertical direction in the drawing). The conductive film 117c is provided so as to extend in a direction parallel to the signal line. The conductive film 103 is electrically connected to the scanning line driver circuit 14 (see FIG. 1(A)). The conductive film 117a functioning as a signal line and the conductive film 117c functioning as a capacitance line are , and is electrically connected to a signal line driving circuit 16 (see FIG. 1(A)).

[0065] The transistor 22 is provided in the area where the scanning line and the signal line intersect. The gate electrode 22 includes a conductive film 103 that functions as a gate electrode, a gate insulating film (not shown in FIG. 2), , a metal oxide film 109a in which a channel region is formed on the gate insulating film, a source The conductive films 117a and 117b function as a drain electrode and a drain electrode, respectively. The conductive film 103 also functions as a scan line, and a region overlapping with the metal oxide film 109a forms a transistor. The conductive film 117a functions as a gate electrode of the transistor 22. The conductive film 117a also functions as a signal line. The region overlapping with the metal oxide film 109a serves as the source electrode or drain of the transistor 22. In addition, in FIG. 2, the scanning lines have metal ends in the top view. The scanning lines are located outside the edge of the oxide film 109a. This acts as a light-shielding film that blocks light from the source. The film 109a is not irradiated with light, and fluctuations in the electrical characteristics of the transistor can be suppressed. In addition, since the metal oxide film 109a is formed using a metal oxide having semiconductor properties, Therefore, a channel region is formed in the metal oxide film 109a.

[0066] The conductive film 117b is electrically connected to the light-transmitting conductive film 119 which functions as a pixel electrode. are actively connected.

[0067] The capacitance element 25 is made up of a metal oxide film 109c formed on the gate insulating film and a pixel electrode. and a light-transmitting conductive film 119 that functions as a gate insulating film and a nitride insulating film provided over the transistor 22. The metal oxide film 109c is a transparent film. Therefore, the capacitor 25 has a light-transmitting property. The metal oxide film 109c is formed by the conductive film 117 which functions as a capacitance line in the opening 115c. It is connected to c.

[0068] In this way, since the capacitance element 25 is transparent, the capacitance element 25 can be made large ( Therefore, it is possible to form the aperture ratio to be 50% or more, preferably 50% or more, while increasing the aperture ratio. It is possible to increase the charge capacity to 55% or more, preferably 60% or more. For example, a semiconductor device with high resolution, such as a liquid crystal display device, can be obtained. In this case, the area of ​​the pixel is small, and the area of ​​the capacitance element is also small. In a semiconductor device with a high capacitance, the charge capacity stored in the capacitance element is small. Therefore, since the capacitor 25 shown in this embodiment mode has a light-transmitting property, the capacitor is provided in the pixel. By doing so, it is possible to obtain a sufficient charge capacity in each pixel while increasing the aperture ratio. In terms of pixel density, it is 200ppi or more, or even 300ppi or more, or even 500ppi. The present invention can be suitably used for high-resolution semiconductor devices having a resolution of i or higher.

[0069] 2, the pixel 13 has a side parallel to the conductive film 103 that functions as a scanning line. The side parallel to the conductive film 117a functioning as a signal line is shorter than the side parallel to the conductive film 117a. The conductive film 117c functioning as a signal line is parallel to the conductive film 117a functioning as a signal line. As a result, the area of ​​the conductive film 117c in the pixel 13 is reduced. This makes it possible to increase the aperture ratio.

[0070] Furthermore, according to one embodiment of the present invention, the aperture ratio can be increased even in a high-resolution display device. This allows for efficient use of light from light sources such as backlights, and reduces the power consumption of the display device. The force can be reduced.

[0071] Next, using the cross-sectional views of the dashed and dotted lines AB and CD shown in Figure 2, A method for manufacturing the element substrate of the device will be described.

[0072] As shown in FIG. 3(A), a conductive film 102 is formed on a substrate 101. Next, a first photo A mask 131 is formed on the conductive film 102 by a photolithography process using a mask. do.

[0073] There is no particular restriction on the material of the substrate 101, but it should be strong enough to withstand the subsequent heat treatment. For example, glass substrates, ceramic substrates, quartz substrates, and A fire substrate or the like may be used as the substrate 101. Also, silicon, silicon carbide, etc. A single crystal semiconductor substrate, a polycrystalline semiconductor substrate, a silicon germanium or the like formed using It is also possible to apply a compound semiconductor substrate, an SOI substrate, etc., and a semiconductor element is formed on these substrates. A substrate provided with a substrate may be used as the substrate 101. When using a substrate, the 6th generation (1500mm x 1850mm) and 7th generation (1870mm) m x 2200mm), 8th generation (2200mm x 2400mm), 9th generation (2400m 10th generation (2950mm x 3400mm) and large area substrates By doing so, a large display device can be manufactured.

[0074] In addition, a flexible substrate is used as the substrate 101, and a conductive film 102 is formed directly on the flexible substrate. Alternatively, a release layer may be provided between the substrate 101 and the conductive film 102, and a transfer film may be formed on the release layer. After forming an element portion having a transistor, the element portion is peeled off from the substrate 101 at the peeling layer, As a result, the device can be mounted on a substrate with low heat resistance or a flexible substrate. A department may be established.

[0075] The conductive film 102 will later become a conductive film 103 that functions as a gate electrode. The conductive film 102 is made of a conductive material that can be used as a gate electrode. 2 is selected from aluminum, chromium, copper, tantalum, titanium, molybdenum, and tungsten. The metal elements mentioned above, or alloys containing the above metal elements, or combinations of the above metal elements It can be formed by using an alloy of manganese and zirconium. Alternatively, the conductive film 102 may have a single layer structure. For example, a single layer of aluminum film containing silicon may be used. a layer structure, a two-layer structure with an aluminum film laminated on a titanium film, and a titanium film laminated on a titanium nitride film. Two-layer structure with tungsten film laminated on titanium nitride film, two-layer structure with tantalum nitride film laminated on titanium nitride film Two-layer structure: tungsten film on tungsten nitride film, copper film on titanium film A two-layer structure in which a titanium film is laminated, and an aluminum film is laminated on top of the titanium film. There are also three-layer structures, such as a titanium film formed on aluminum. , a film of an element selected from tungsten, molybdenum, chromium, neodymium, and scandium; Alternatively, an alloy film made up of a combination of multiple layers or a nitride film may be used.

[0076] The conductive film 102 may be formed of an indium tin oxide film or an indium oxide film containing tungsten oxide. oxide film, indium zinc oxide film containing tungsten oxide, indium zinc oxide film containing titanium oxide oxide film, indium tin oxide film containing titanium oxide, indium zinc oxide film, silicon oxide A film formed of a light-transmitting conductive material such as an indium tin oxide film doped with indium is suitably used. In addition, a film formed of the above-mentioned light-transmitting conductive material and the above-mentioned metal It may also have a laminated structure of films formed from elements.

[0077] Here, a tungsten film having a thickness of 100 nm is deposited by sputtering as the conductive film 102. Next, a mask is formed by a photolithography process.

[0078] Next, a part of the conductive film 102 is etched using a mask 131 to form a gate electrode. A functional conductive film 103 is formed by dry etching or / and wet etching. The conductive film 102 can be etched by using a method. After that, the mask 131 is removed. (See Figure 3(B)).

[0079] Here, a tungsten film formed as the conductive film 102 is dry-etched using a mask. Then, a conductive film 103 that functions as a gate electrode is formed.

[0080] Next, as shown in FIG. 3(C), the insulating film 105, the insulating film 106, the metal oxide film 108, An insulating film 110 is then formed. Next, a photolithography process is performed using a second photomask. By this process, masks 133 and 135 are formed on the insulating film 110. The mask is characterized by using a multi-tone mask.

[0081] A multi-level photomask is a mask that can perform exposure with multiple levels of light intensity. Specifically, there are gray-tone masks and half-tone masks. A light-shielding portion and a diffraction grating are formed on a substrate having optical properties. The diffraction grating has slits, dots, and The intervals between the light transmitting regions such as meshes are equal to or less than the resolution limit of the light used for exposure. This configuration controls the light transmittance. The semi-transmitting portion controls the transmittance of light used for exposure. .

[0082] By using a multi-tone mask, three levels of light intensity can be achieved: exposed area, semi-exposed area, and unexposed area. As a result, by using a multi-tone photomask, it is possible to perform exposure in one exposure. and a development process to form resist masks with multiple (typically two) thicknesses. This allows for a reduction in the number of photomasks required. In the process of forming the oxide films 109a and 109b and the insulating film 111c, a multi-tone photomask By using this, it is possible to reduce the number of photomasks by one.

[0083] The insulating film 105 and the insulating film 106 will later become a gate insulating film. The conductive film 103 functions as a gate electrode and the metal oxide film 108 is To prevent the diffusion of impurities, it is preferable to form the insulating film using a nitride insulating film. The insulating film 106 contacts the metal oxide film 108. In order to reduce the surface state density, the insulating film 106 is preferably formed using an oxide insulating film.

[0084] The insulating film 105 is made of silicon nitride, silicon nitride oxide, aluminum nitride, or aluminum nitride oxide. The insulating film 10 may be formed using aluminum or the like, and may be provided as a laminated layer or a single layer.

[0085] The insulating film 106 is made of silicon oxide, silicon oxynitride, aluminum oxide, hafnium oxide, or the like. The insulating layer may be formed using aluminum, gallium oxide, Ga-Zn-based metal oxide, or the like. is provided in a single layer.

[0086] The insulating film 106 is made of hafnium silicate (HfSiO x ), nitrogen is added Hafnium silicate (HfSi x O y N z ), nitrogen-doped hafnium aluminate (HfAl x O y N z ), high-k materials such as hafnium oxide and yttrium oxide By forming the gate electrode using this material, it is possible to reduce gate leakage of the transistor.

[0087] The total thickness of the insulating film 105 and the insulating film 106 is preferably 5 nm or more and 400 nm or less. Preferably, the thickness is 10 nm or more and 300 nm or less, and more preferably, 50 nm or more and 250 nm or less. It is good.

[0088] The insulating film 105 and the insulating film 106 are formed by a CVD method, a sputtering method, a vapor deposition method, a coating method, or the like. It can be used as appropriate.

[0089] By providing the insulating film 105 made of a nitride insulating film as a part of the gate insulating film, Impurities from the conductive film 103 functioning as a gate electrode, typically hydrogen, nitrogen, alkali, It is possible to prevent metals, alkaline earth metals, etc. from migrating to the metal oxide film 109a. can.

[0090] In addition, as a gate insulating film, an insulating film formed of an oxide insulating film on the metal oxide film 109a side is used. By providing the film 106, the defect level at the interface between the gate insulating film and the metal oxide film 109a is As a result, a transistor with little deterioration in electrical characteristics can be obtained. This can be done.

[0091] The metal oxide film 108 is typically an In-Ga oxide film, an In-Zn oxide film, or an In -M-Zn oxide film (M is Al, Ga, Ti, Y, Zr, La, Ce, or Nd), etc. Since the metal oxide film has semiconductor properties, it is possible to use the metal oxide film as an oxide semiconductor. It is also possible to say this.

[0092] When the metal oxide film 108 is an In-M-Zn oxide film, the sum of In and M is When the atomic percentage is 100 atomic %, the atomic ratio of In to M is preferably 25 atomic %. mic%, M is less than 75 atomic %, and more preferably In is 34 atomic % mic%, and M is less than 66 atomic%.

[0093] The energy gap of the metal oxide film 108 is 2 eV or more, preferably 2.5 eV or more. , and more preferably 3 eV or more. By forming the transistor using the above, the off-state current of a transistor to be formed later can be reduced. .

[0094] The metal oxide film 108 is a metal oxide film with a low carrier density. The metal oxide film 108 has a carrier density of 1×10 17 pieces / cm 3 Less than 1 × 10 15 pieces / cm 3 or less, more preferably 1 × 10 13 pieces / cm 3 Below, more preferably 1 x10 11 pieces / cm 3 The following metal oxide films are used:

[0095] The thickness of the metal oxide film 108 is 3 nm or more and 200 nm or less, preferably 3 nm or more and 10 0 nm or less, and more preferably 3 nm or more and 50 nm or less.

[0096] The metal oxide film 108 can be formed by a sputtering method, a coating method, a pulsed laser deposition method, a laser It can be formed by using an ablation method or the like.

[0097] When the metal oxide film 108 is formed by sputtering, a plasma generating method is required. The power supply may be an RF power supply, an AC power supply, a DC power supply, or the like.

[0098] The sputtering gas is a rare gas (typically argon), oxygen, or a mixture of rare gas and oxygen. In the case of a mixture of rare gas and oxygen, the ratio of the oxygen gas to the rare gas is A higher ratio is preferred.

[0099] The metal oxide film 108 is an In-M-Zn oxide film (M is Al, Ti, Ga, Y, Zr, In the case of La, Ce, Nd or Hf, it is used to deposit In-M-Zn oxide films. The atomic ratio of the metal elements in the sputtering target is In:M:Z. If n=x1:y1:z1 、 x1 / y1 is between 1 / 3 and 6, and between 1 and 6. and z1 / y1 is preferably 1 / 3 or more and 6 or less, and more preferably 1 or more and 6 or less. By setting z1 / y1 to 1 or more and 6 or less, the metal oxide film 108 can be formed as described later. CAAC-OS(C Axis Aligned Crystalline Oxid e) Semiconductor film is easily formed. Typical examples of the molecular ratio are In:M:Zn=1:1:1, In:M:Zn=3:1:2, The atomic ratio of the metal oxide film 108 to be formed is, for example, In:M:Zn=5:5:6. are the plus or minus of the atomic ratio of the metal elements contained in the target as errors. Includes a 40% variation.

[0100] In order to obtain a highly pure metal oxide film 108, the chamber must be evacuated to a high vacuum. In addition, it is also necessary to increase the purity of the sputtering gas. Gongas has a dew point of -40°C or less, preferably -80°C or less, more preferably -100°C or less. Preferably, the gas is highly purified to -120°C or less. This can prevent moisture and other substances from being absorbed into the film as much as possible.

[0101] The insulating film 110 is formed by oxidation in order to reduce the interface state at the interface with the metal oxide film 108. The insulating film 110 is preferably a silicon oxide insulating film. Silicon, aluminum oxide, hafnium oxide, gallium oxide or Ga-Zn-based metal oxide The insulating film 10 may be formed using a compound such as a fluorine compound, and may be provided as a laminated layer or a single layer.

[0102] In addition, a part or the whole of the insulating film 110 contains more oxygen than the stoichiometric composition. It is preferable to form the insulating film using an oxide insulating film containing oxygen having a stoichiometric composition. When an oxide insulating film contains more oxygen than the element, some of the oxygen is released by heating. The oxide insulating film containing more oxygen than the oxygen that satisfies the optical composition has a TDS (Thermal Defect System) In the Desorption Spectroscopy analysis, the surface temperature was 100°C. Equivalent to oxygen atoms in heat treatment at temperatures above 700°C or below 100°C or below 500°C The amount of oxygen released is 1.0×10 18 atoms / cm 3 or more, preferably 3.0 x 1 0 20 atoms / cm 3 The oxide insulating film is as described above.

[0103] Furthermore, it is preferable that the insulating film 110 has a small number of defects. The spin density of the signal at g=2.001 originating from the silicon dangling bond is 1.5 x 10 18 spins / cm 3 Less than or even 1×10 18 spins / cm 3 Below Bottom, 1×10 17 spins / cm 3 or less, and more preferably below the lower limit of detection. .

[0104] The thickness of the insulating film 110 is 30 nm or more and 500 nm or less, preferably 50 nm or more and 400 nm or less. nm or less.

[0105] The insulating film 110 is an oxide insulating film containing more oxygen than the oxygen required for the stoichiometric composition. By forming the insulating film 110 using a metal oxide film, oxygen released from the insulating film 110 by heat treatment can be absorbed by the metal oxide film. As a result, the oxygen contained in the metal oxide film 108 can be transferred to the metal oxide film 108. Defects can be reduced.

[0106] The insulating film 110 can be formed by a sputtering method, a CVD method, or the like.

[0107] When the insulating film 110 is formed by the CVD method, the source gas is a silicon-containing deposit. It is preferable to use an oxidizing gas and an insulating gas. Representative examples of the silicon-containing deposition gas are: Examples of oxidizing gases include silane, disilane, trisilane, and fluorinated silane. Examples include oxygen, ozone, nitrous oxide, and nitrogen dioxide.

[0108] An oxide insulating film containing more oxygen than the oxygen required for the stoichiometric composition of the insulating film 110 When forming the film using the above method, a substrate is placed in a processing chamber of a plasma CVD apparatus that has been evacuated. The plate is maintained at a temperature of 180°C or higher and 280°C or lower, more preferably 200°C or higher and 240°C or lower, The raw material gas is introduced into the processing chamber, and the pressure in the processing chamber is set to 100 Pa or more and 250 Pa or less, More preferably, the pressure is 100 Pa or more and 200 Pa or less, and the pressure applied to the electrode provided in the processing chamber is 0.1 7W / cm 2 More than 0.5W / cm 2 or less, more preferably 0.25 W / cm 2 Over 0. 35W / cm 2Under the following conditions of high frequency power supply, silicon oxide film or oxynitride film A silicon film can be formed.

[0109] The conditions for forming the insulating film 110 are as follows: a high frequency voltage of the above power density in a reaction chamber of the above pressure; By supplying power, the decomposition efficiency of the source gas in the plasma increases, and oxygen radicals increase. As the oxidation of the source gas progresses, the oxygen content in the insulating film 110 becomes higher than the stoichiometric composition. On the other hand, in the film formed at the above substrate temperature, the bonding strength between silicon and oxygen is As a result, the stoichiometric amount of oxygen in the film is reduced by the heat treatment in the subsequent process. An insulating film that contains more oxygen than satisfies the stoichiometric composition and loses some of the oxygen when heated 110 can be formed.

[0110] The insulating film 110 has a multilayer structure of a first insulating film and a second insulating film. The second insulating film is formed using an oxide insulating film that can transmit oxygen. An acid that contains more oxygen than the stoichiometric composition and loses some of the oxygen when heated. By forming the layered structure, the second insulating film can be formed. As a result, the first insulating film acts as a protective film for the metal oxide film. The second insulating film can be formed using high frequency power with high power density while reducing the do.

[0111] Alternatively, an insulating film is formed by a sputtering method, a CVD method, or the like, and then oxygen is added to the insulating film. By adding oxygen, the insulating film 110 can be formed. The method of adding the ion is ion doping, ion implantation, etc. Oxygen is added to the insulating film by exposing the insulating film to plasma containing oxygen generated in the atmosphere. It is possible.

[0112] Here, a silicon nitride film having a thickness of 400 nm is formed as the insulating film 105 by the CVD method. Also, as the insulating film 106, a silicon oxynitride film having a thickness of 50 nm is formed by the CVD method. In addition, as the metal oxide film 108, an In-Ga-Zn oxide target A 35-nm thick I film was formed by sputtering using (In:Ga:Zn=1:1:1). An n-Ga-Zn oxide film is formed. Silane and nitrous oxide at a flow rate of 4000 sccm were used as raw material gases, and the pressure in the reaction chamber was set to 200 The substrate temperature was set to 220°C, and a 1500W high-frequency power supply was used at 27.12MHz. The insulating film 110 is formed by a plasma CVD method in which high frequency power is supplied to parallel plate electrodes. A silicon oxynitride film of 400 nm is formed. The plasma CVD equipment has an electrode area of ​​6 000cm 2 It is a parallel plate type plasma CVD device that supplies power per unit area. This is converted to 0.25W / cm2 of power per square meter (power density). 2 Also, halftone matrices Masks 133 and 135 are formed using a mask.

[0113] Next, a part of the insulating film 110 is etched using the masks 133 and 135, and the insulating film 110 is removed as shown in FIG. As shown in Fig. 1D), insulating films 111a and 111b are formed by dry etching or / and The insulating film 110 can be etched using a wet etching method. Then, a part of the metal oxide film 108 is etched using the masks 133 and 135 to form a metal oxide film. The oxide films 109a and 109b are formed by dry etching or / and wet etching. The metal oxide film 108 can be etched using a etching method.

[0114] Here, the insulating film 110 and the metal oxide film 108 are each removed by dry etching. A portion of the substrate is etched.

[0115] Next, the masks 133 and 135 are processed. Here, the size of the mask 133 is reduced. At the same time, the mask 135 is removed. The masks 133 and 135 are exposed to the generated plasma by plasma treatment. 35. The oxygen-containing atmosphere includes oxygen, ozone, nitrous oxide, and nitrogen dioxide. The atmosphere contains an oxidizing gas such as oxygen. The masks 133 and 135 may be exposed to the plasma generated by the plasma treatment. An example of such an apparatus is an ashing apparatus.

[0116] Here, the masks 133 and 135 are exposed to plasma generated in an atmosphere containing oxygen. In this way, the masks 133 and 135 are processed.

[0117] As a result, as shown in FIG. 3(D), the mask 133 is recessed to form a mask 137. Furthermore, the mask 135 is removed, and the insulating film 111b is exposed. In FIG. 3(D), the dashed lines correspond to the masks 133 and 135 shown in FIG. 3(C).

[0118] Next, a part of the insulating film 111a is etched using the mask 137, and the insulating film 111a is formed as shown in FIG. As shown in the figure, the insulating film 111c is formed and the insulating film 111b is removed. The insulating films 111a and 111b are etched using a etching method and / or a wet etching method. Here, the insulating film 111a is etched, and the metal oxide The films 109a and 109b are not etched, or the metal oxide film 10 is formed thicker than the insulating film 111a. It is preferable to use conditions under which the etching rate of 9a and 109b is small.

[0119] Here, a part of the insulating film 111a is etched by dry etching. Then, the insulating film 111b is removed.

[0120] As a result, the insulating film 111c that functions as a channel protective film can be formed. In addition, since no mask is formed on the insulating film 111b, the insulating film 111b is removed and the metal The surface of the oxide film 109b is exposed. Therefore, the insulating film 106 is also etched in this process, Between the insulating film 105 and the metal oxide film 109a, the edge is approximately aligned with the metal oxide film 109a. An insulating film 107a is formed. A metal oxide film 109b is formed between the insulating film 105 and the metal oxide film 109b. An insulating film 107b is formed whose edge is substantially aligned with the metal oxide film 109b.

[0121] Through the above process, a metal oxide film including the channel region of a transistor can be formed using a single photomask. oxide films 109a and 109b and an insulating film 111c that functions as a channel protection film. It is possible.

[0122] In the etching process for forming the insulating film 111c, the metal oxide film 109 In a and 109b, the area exposed to plasma is damaged and oxygen vacancies are formed. Therefore, the area of ​​the metal oxide film 109a that is not covered with the insulating film 111c, and The conductivity of the metal oxide film 109b increases.

[0123] Next, a heat treatment is carried out. The temperature of the heat treatment is typically 150° C. or higher but not higher than the substrate distortion point. Preferably, the temperature is 300°C or higher and 500°C or lower, more preferably, 320°C or higher and 470°C or lower. .

[0124] The heat treatment can be carried out using an electric furnace, an RTA device, or the like. Therefore, heat treatment can be performed at a temperature above the strain point of the substrate for a short period of time. The processing time can be reduced.

[0125] Heat treatment is carried out in a nitrogen, oxygen, or ultra-dry air (water content of 20 ppm or less, preferably 1 ppm). pm or less, preferably 10 ppb or less air), or rare gases (argon, helium, etc.) The above-mentioned nitrogen, oxygen, ultra-dry air, or rare gas may be mixed with hydrogen, water, or the like. It is preferable that the above is not included.

[0126] By this heat treatment, part of the oxygen contained in the insulating film 111c is converted into the metal oxide film 109a. By moving the oxygen atoms, oxygen vacancies in the metal oxide film 109a can be reduced.

[0127] When the insulating film 110 is formed on the metal oxide film 108 while heating, the metal oxide The oxygen is transferred to the metal oxide film 108, and oxygen vacancies contained in the metal oxide film 108 are compensated for. Therefore, the heat treatment may not be performed.

[0128] Here, after heat treatment at 450°C for 1 hour in a nitrogen atmosphere, The mixture is heated in a gas atmosphere at 450°C for 1 hour.

[0129] Next, as shown in FIG. 4(A), the insulating film 105, the insulating film 107, the metal oxide film 109a An insulating film 112 is formed on the insulating films 109b and 111c. A mask 139 is formed on the insulating film 112 by a photolithography process using a mask. .

[0130] A nitride insulating film is provided as the insulating film 112. Examples of nitride insulating films include silicon nitride, Silicon nitride oxide, aluminum nitride, aluminum nitride oxide, etc. In this way, a nitride insulating film containing hydrogen may be formed.

[0131] The thickness of the insulating film 112 is 10 nm or more and 400 nm or less, and more preferably 50 nm or more and 300 nm or less. 00nm or less.

[0132] The insulating film 112 can be formed by a sputtering method, a CVD method, or the like. After forming an insulating film by using a sputtering method, a CVD method, or the like, hydrogen is added to the insulating film. The method of adding hydrogen to the insulating film may include ion doping, ion Alternatively, the insulating film can be exposed to plasma generated in a gas atmosphere containing hydrogen. In this way, hydrogen can be added to the insulating film.

[0133] Here, the insulating film 112 is formed by a plasma process using silane, ammonia, and nitrogen as raw material gases. A silicon nitride film with a thickness of 100 nm is formed by the Zuma CVD method.

[0134] Plasma damage occurs when forming the insulating film 112 on the insulating film 111c, causing metal Oxygen vacancies are formed in the oxide films 109a and 109b. 9a, the area not covered with the insulating film 111c and the conductive metal oxide film 109b. In addition, by using a nitride insulating film containing hydrogen as the insulating film 112, the insulating Hydrogen moves from the film 112 to the metal oxide films 109a and 109b. Hydrogen moves to the oxygen vacancies. As a result, the metal oxide film 109b becomes conductive. The metal oxide film 109c has high conductivity. 9 c functions as one electrode of the capacitor element 25 .

[0135] The metal oxide film 109a is in contact with the insulating film 113 on the outside of the insulating film 111c. Since the insulating film 111c is an oxide insulating film, the metal oxide film 10 in contact with the insulating film 111c The metal oxide film 109a functions as a channel region of the transistor. Therefore, the region in contact with the insulating film 113 has high conductivity, similar to the metal oxide film 109c. That is, the metal oxide film 109c functions as a low resistance region. It is possible to increase the on-current of the transistor and also to enhance the field effect mobility. It is possible.

[0136] The nitride insulating film also functions as a blocking film for water, hydrogen, etc. By providing a nitride insulating film as 12, hydrogen and water from the outside are prevented from entering the metal oxide film 109a. It is possible to prevent intrusions such as

[0137] The metal oxide film 109a and the metal oxide film 109c are both formed on the gate insulating film. However, the impurity concentration is different. The impurity concentration of the film 109c is high. For example, the hydrogen concentration contained in the metal oxide film 109a is 5×10 19 atoms / cm 3 Less than 5 x 10 18 atoms / cm 3 less than , preferably 1 x 10 18 atoms / cm 3 Less than or equal to 5 × 10 17 ato ms / cm 3 or less, more preferably 1 × 10 16 atoms / cm 3 is less than or equal to metal The hydrogen concentration in the oxide film 109c is 8×10 19 or more, preferably 1 × 10 20 a toms / cm 3 More preferably, 5 × 10 20 The above is the case. The hydrogen concentration in the metal oxide film 109c is twice as high, preferably 10 times as high as that in the metal oxide film 109a. That's all.

[0138] The metal oxide film 109c has a lower resistivity than the metal oxide film 109a. The resistivity of the film 109c is 1×10 -8 more than 1x10 - 1 It is preferably less than 1×10 -3 Ωcm or more 1×10 4 Ωcm not yet More preferably, the resistivity is less than 1×10 -3 Ωcm or more 1×10 -1 Less than Ωcm It is good.

[0139] Next, a heat treatment may be performed. The temperature of the heat treatment is typically 150° C. or higher and 40° C. or lower. 0°C or lower, preferably 300°C or higher and 400°C or lower, preferably 320°C or higher and 370°C or lower Let's say.

[0140] In the transistor 22, the insulating film 105 formed of a nitride insulating film and the nitride insulating film The insulating film 112 is in contact with the insulating film 105, and the metal oxide film 1 is formed between the insulating films 105 and 112. The nitride insulating film has a low diffusion coefficient for hydrogen, water, and oxygen. The insulating film 111c has a small number of carbon atoms and has a high blocking property against hydrogen, water, and oxygen. The insulating film is formed using an oxide insulating film containing more oxygen than the oxygen required for the stoichiometric composition. As a result, the diffusion of oxygen contained in the metal oxide film 109a to the outside is suppressed during the heat treatment. In addition, the diffusion of oxygen contained in the metal oxide film 109a to the outside can be suppressed. As a result, oxygen deficiency in the metal oxide film 109a can be reduced. Furthermore, it is possible to suppress the diffusion of hydrogen, water, etc. from the outside into the metal oxide film 109a. As a result, hydrogen, water, etc. in the metal oxide film 109a can be reduced. Therefore, a highly reliable transistor can be manufactured.

[0141] Here, heat treatment is performed in a nitrogen and oxygen atmosphere at 350° C. for 1 hour.

[0142] Next, a part of the insulating film 112 was etched using the mask 139, and the mask was removed. That is, as shown in FIG. 4B, the insulating film 11 having openings 115a, 115b, and 115c In the openings 115a and 115b, a part of the metal oxide film 109a is exposed. In the opening 115c, a part of the metal oxide film 109c is exposed. The insulating film 112 is etched using a dry etching method and / or a wet etching method. Next, the mask 139 is removed.

[0143] Here, a part of the insulating film 112 is etched by dry etching.

[0144] Next, as shown in FIG. 4(C), the exposed portion of the metal oxide film 109a and the metal oxide film 109 A conductive film 116 is formed on the exposed portion of the insulating film 113 and the insulating film 113. Next, a fourth photomask By a photolithography process using Form 141c.

[0145] The conductive film 116 is formed by forming conductive films 117a and 117b, which will later function as a pair of electrodes, and a capacitor line. Therefore, the conductive film 116 can be used as an electrode. The conductive film 116 can be formed using any suitable conductive material. copper, yttrium, zirconium, molybdenum, silver, tantalum, or tungsten The metal is used as a single layer or a laminated structure. For example, a single layer structure of aluminum film containing silicon, an aluminum film on a titanium film, Two-layer structure with aluminum film laminated on tungsten film, two-layer structure with copper-magnet Two-layer structure with copper film laminated on top of a titanium film. a two-layer structure in which a copper film is laminated on a tungsten film; a two-layer structure in which a titanium film or titanium nitride film is laminated on a tungsten film; Then, an aluminum film or a copper film is laminated on the titanium film or the titanium nitride film, and A three-layer structure in which a titanium film or titanium nitride film is formed on top of the above, a molybdenum film or a nitride film A molybdenum film and an aluminum film or a molybdenum nitride film are laminated on the molybdenum film or the molybdenum nitride film. A three-layer structure in which a copper film is laminated on top of a molybdenum film or molybdenum nitride film is formed on top of that. The transparent conductive material containing indium oxide, tin oxide or zinc oxide is used. It may be formed as follows.

[0146] The conductive film 116 is formed by a sputtering method, a CVD method, an evaporation method, or the like.

[0147] Here, the conductive film 116 is formed of tungsten with a thickness of 50 nm by a sputtering method. A film and a copper film having a thickness of 300 nm are formed.

[0148] Next, a part of the conductive film 116 is etched using the masks 141a, 141b, and 141c. The conductive films 117a and 117b function as a pair of electrodes, and the conductive film 117a functions as a capacitance line. A film 117c is formed by dry etching or / and wet etching. The conductive film 116 can be etched. 141c is removed (see FIG. 4(D)).

[0149] The nitride film is formed around the area where the metal oxide film 109a and the conductive films 117a and 117b are in contact with each other. The insulating film 113 is formed of a nitride insulating film. The diffusion coefficient of copper in the nitride insulating film is Therefore, even a part of the conductive films 117a and 117b can be prevented from diffusing copper. Alternatively, when the entire surface is made of a copper film, the insulating film 113 functions as a barrier film for copper. This reduces copper diffusion into the channel region and reduces variations in the electrical characteristics of the transistor. It is possible.

[0150] In addition, in the conductive films 117a and 117b, a region in contact with the metal oxide film 109a is provided with a tantalum oxide film. elemental or non-elementary tungsten, titanium, aluminum, copper, molybdenum, chromium, or tantalum By using a conductive material that easily bonds with oxygen, such as an alloy, the oxygen in the metal oxide film 109a can be The metal oxide film 109a is drawn into a conductive material that easily bonds with oxygen. Stainless steel, titanium, aluminum, copper, molybdenum, chromium, or tantalum alone or In some cases, some of the constituent elements of the alloy may be mixed in. As a result, the metal oxide film 109a In this case, a low resistance region is formed in the vicinity of the region in contact with the conductive films 117a and 117b. The resistive region has high conductivity, so that the contact between the metal oxide film 109a and the conductive films 117a and 117b is It is possible to reduce contact resistance and increase the on-current of the transistor. be.

[0151] Next, as shown in FIG. 5A, the insulating film 113 and the conductive films 117a, 117b, and 117c are A light-transmitting conductive film 118 is formed on the insulating film 114. Next, a photoresist is formed on the insulating film 114 using a fifth photomask. A mask 143 is formed over the conductive film 118 by a lithography process.

[0152] The conductive film 118 will later become a conductive film 119 that functions as a pixel electrode. The conductive film 118 is made of a conductive material that can be used as a pixel electrode. , indium tin oxide film, indium oxide film containing tungsten oxide, tungsten oxide Indium zinc oxide film containing titanium oxide, indium oxide film containing titanium oxide Indium tin oxide film containing indium, indium zinc oxide film containing indium, silicon oxide added film containing indium A conductive film formed of a light-transmitting conductive material such as a tin oxide film can be used. .

[0153] The conductive film 118 is formed by a sputtering method, a vapor deposition method, a coating method, or the like.

[0154] Here, a 100 nm thick ITO film is formed as the conductive film 118 by sputtering. Form.

[0155] Next, a part of the conductive film 118 is etched using a mask 143 to form a film functioning as a pixel electrode. The conductive film 119 is formed on the conductive film 11 which functions as a pair of electrodes. 7b and overlaps with the metal oxide film 109c via the insulating film 113. The conductive film 118 is formed by dry etching or / and wet etching. After that, the mask 143 is removed (see FIG. 5(B)). .).

[0156] Here, part of the conductive film 118 is etched by wet etching.

[0157] Through the above steps, the conductive film 103 functioning as a gate electrode and the gate insulating film The insulating films 105 and 106a, the metal oxide film 109a, and a part of the metal oxide film 109a are covered with the insulating films 105 and 106a. The insulating film 111c is in contact with the metal oxide film 109a and functions as a pair of electrodes. A transistor 22 having the gate electrodes 7a and 117b can be fabricated. A conductive film 119 is formed in contact with the conductive film 117b included in 22 and functions as a pixel electrode. In addition, the metal oxide film 109c formed on the insulating film 106b and the insulating film 11 3 and the conductive film 119, a capacitor element 25 can be manufactured. The element substrate having the capacitor 22, the conductive film 119 functioning as a pixel electrode, and the capacitor element 25 is In this embodiment, the metal oxide film and the carbon black film are formed by using five photomasks. The protective film for the panel is formed using a single photomask, which is necessary for fabricating the element substrate. This allows for the reduction of the number of photomasks required.

[0158] In addition, the semiconductor device described in this embodiment has a metal oxide film including a channel region of a transistor. At the same time as forming the metal oxide film, a metal oxide film that will become one of the electrodes of the capacitance element is formed. A metal oxide film including a channel region of a capacitor and a metal oxide film that will be one of the electrodes of a capacitor element. The conductive film that functions as a pixel electrode is made of the same metal element as the capacitor element. For this reason, a new conductive film is formed to form a capacitor element. Since the step of forming a capacitor is not required, the manufacturing steps of the display device can be reduced. Since both the metal oxide film 109c and the conductive film 119, which are electrodes, have light-transmitting properties, As a result, the area occupied by the capacitor element can be increased while increasing the aperture ratio of the pixel. Furthermore, a display device with reduced power consumption can be manufactured.

[0159] <About metal oxide films> When hydrogen is added to an oxide semiconductor with oxygen vacancies, hydrogen enters the oxygen vacancy sites. A donor level is formed near the conduction band. As a result, the oxide semiconductor has high conductivity. The oxide semiconductor that has become a conductor can be called an oxide conductor. Oxide semiconductors have a large energy gap and therefore transmit visible light. On the other hand, an oxide conductor is an oxide semiconductor that has a donor level near the conduction band. Therefore, the influence of absorption due to the donor level is small, and the transparency to visible light is the same as that of an oxide semiconductor. It has photosensitivity.

[0160] Here, a film formed of an oxide semiconductor such as that used for the metal oxide film 109a (hereinafter referred to as The metal oxide film 109c is an oxide semiconductor film (hereinafter referred to as an oxide semiconductor film (OS)). Resistance in a film formed of an oxide conductor (hereinafter referred to as an oxide conductor film (OC)) The temperature dependency of the efficiency will be explained using FIG. 13. In FIG. 13, the horizontal axis represents the measurement temperature. The vertical axis shows the resistivity, and the vertical axis shows the measurement results for the oxide semiconductor film (OS). The measurement results for the oxide conductor film (OC) are indicated by squares.

[0161] The sample including the oxide semiconductor film (OS) was formed on a glass substrate with an atomic ratio of In:Ga Zn=1:1:1.2 sputtering target. An In-Ga-Zn oxide film with a thickness of 35 nm was formed, and the atomic ratio was In:Ga:Zn=1:4. :5 sputtering target was used to deposit a 20 nm thick In- A Ga-Zn oxide film was formed, and after heat treatment in a nitrogen atmosphere at 450°C, and heat treatment in a mixed gas atmosphere of silicon and oxygen, and then a silicon oxynitride film is formed by plasma CVD. was formed and produced.

[0162] The sample containing the oxide conductor (OC) film was formed on a glass substrate with an atomic ratio of In:Ga. Zn=1:1:1 sputtering target was used to deposit a 10 ... After forming a 00 nm In-Ga-Zn oxide film and heat-treating it in a nitrogen atmosphere at 450°C, The silicon nitride film was then heated at 450°C in a mixed gas atmosphere of nitrogen and oxygen, and then deposited by plasma CVD. It was prepared by forming a com film.

[0163] As can be seen from FIG. 13, the temperature dependence of resistivity in the oxide conductor film (OC) is The temperature dependence of resistivity is smaller than that of oxide semiconductor films (OS). Typically, it is 80K or higher. The resistivity change rate of the oxide semiconductor film (OC) at 290K or less is less than ±20%. Alternatively, the rate of change in resistivity between 150K and 250K is less than ±10%. That is, an oxide conductor is a degenerate semiconductor, and the conduction band edge and the Fermi level are coincident or approximately coincident. Therefore, it is considered that the oxide conductor film is used for the resistance element, wiring, and capacitance element. It can be used for electrodes, pixel electrodes, common electrodes, etc.

[0164] <Oxide Semiconductor Films and Metal Oxide Films> Next, one embodiment applicable to a metal oxide film and an oxide semiconductor film having semiconductor properties will be described. Here, an oxide semiconductor film will be used as a typical example. The structure of the semiconductor film can be applied to the metal oxide film.

[0165] The oxide semiconductor film is preferably a CAAC-OS film. The S film has a c-axis orientation and clear crystal grain boundaries (also called grain boundaries) can be confirmed. As a result, in a channel-etched transistor, As a result, the amount of over-etching of the oxide semiconductor film when forming the oxide semiconductor film is small. By using a CAAC-OS film as the main film, a channel-etched transistor is fabricated. In addition, a channel-etched transistor can be formed by dividing the gap between a pair of electrodes, i.e., the channel The channel length is set to 0.5 μm or more and 6.5 μm or less, preferably 1 μm or more and 6.5 μm or less. It is possible to make it smaller than μm.

[0166] The oxide semiconductor film is formed by using an oxide semiconductor having a single crystal structure (hereinafter referred to as a single crystal oxide semiconductor). ), a polycrystalline oxide semiconductor (hereinafter referred to as a polycrystalline oxide semiconductor), and a microcrystalline oxide semiconductor. The oxide semiconductor layer may be made of one or more of the following oxide semiconductors (hereinafter referred to as microcrystalline oxide semiconductors): Below, we will discuss CAAC-OS, single-crystalline oxide semiconductors, polycrystalline oxide semiconductors, and microcrystalline oxide semiconductors. The conductor will now be described.

[0167] <caac-os> The CAAC-OS film is one of oxide semiconductor films having multiple crystal parts. The crystals contained in the AC-OS film have a c-axis orientation. The area of ​​the crystal part contained in the C-OS film is 2500 nm 2 More preferably, 5 μm or more 2 Below More preferably 1000 μm or more 2 In addition, in the cross-sectional TEM image, the crystal By having 50% or more, preferably 80% or more, and more preferably 95% or more of the above-mentioned portion, The resulting thin film has properties close to those of a crystal.

[0168] The CAAC-OS film was observed under a transmission electron microscope (TEM). When observed under a tron ​​microscope, clear boundaries between the crystalline parts are observed. It is not possible to confirm the grain boundary. It can be said that the AAC-OS film is less susceptible to the decrease in electron mobility caused by grain boundaries.

[0169] The CAAC-OS film was observed by TEM from a direction roughly parallel to the sample surface (cross-sectional TEM observation). When observed, it can be confirmed that metal atoms are arranged in layers in the crystalline part. Each layer of the CAAC-OS film is formed on a surface (also called a surface to be formed) or on a concave surface of the upper surface. The shape reflects the convexity and is aligned parallel to the surface on which the CAAC-OS film is formed or the top surface. 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 a state in which two straight lines are arranged at an angle of 80° or more and 100° or less. This includes angles between 85° and 95°.

[0170] On the other hand, the CAAC-OS film was observed by TEM from a direction approximately perpendicular to the sample surface (plane T EM observation reveals that metal atoms are arranged in triangular or hexagonal shapes in the crystalline region. However, no regularity was observed in the arrangement of metal atoms between different crystal regions. do not have.

[0171] When electron diffraction is performed on the CAAC-OS film, spots (bright spots) indicating orientation are observed. is observed.

[0172] Cross-sectional and planar TEM observations revealed that the crystals in the CAAC-OS film had an orientation. It can be seen that this is the case.

[0173] X-ray diffraction (XRD) of the CAAC-OS film The structure of the CAAC-OS film was analyzed using the out-of-plane method. In the analysis, a peak may appear at a diffraction angle (2θ) of around 31°. This peak is due to the Since it is attributed to the (00x) plane (x is an integer) of the nGaZn oxide crystal, The crystals of the OS film have a c-axis orientation, and the c-axis is oriented in a direction approximately perpendicular to the surface on which the film is formed or the upper surface. It can be confirmed that there is.

[0174] On the other hand, the in-p X-rays incident on the CAAC-OS film are perpendicular to the c-axis. In the Lane analysis, a peak may appear around 2θ of 56°. The crystal structure of InGaZn oxide is composed of (110) plane. In the case of a crystalline oxide semiconductor film, 2θ is fixed at around 56°, and the normal vector of the sample surface is aligned with the axis (φ When the analysis (φ scan) is performed while rotating the sample around the (110) axis, the bonds equivalent to the (110) plane are observed. In contrast, in the case of the CAAC-OS film, 2 peaks are observed. Even when θ is fixed at around 56° and φ is scanned, no clear peak appears.

[0175] From the above, it can be concluded that the orientation of the a-axis and b-axis is uniform between different crystal regions in the CAAC-OS film. Although it is irregular, it has a c-axis orientation, and the c-axis is parallel to the normal vector of the surface on which it is formed or the upper surface. Therefore, the layered structure confirmed by the cross-sectional TEM observation mentioned above is consistent with the Each layer of arranged metal atoms is a plane parallel to the ab plane of the crystal.

[0176] The crystals are 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.

[0177] Furthermore, the crystallinity of the CAAC-OS film may not be uniform. When the crystalline part of the film is formed by crystal growth from the vicinity of the top surface of the CAAC-OS film, The area near the surface may have a higher crystallinity than the area near the surface to be formed. When impurities are added to the AC-OS film, the crystallinity of the region where the impurities are added changes, and the Regions of differing crystallinity may be formed.

[0178] In addition, in the out-of-plane analysis of the CAAC-OS film, 2θ was 31° In addition to the peaks around 2θ around 36°, a peak may also appear. The peaks around the center of the CAAC-OS film indicate that the CAAC-OS film contains crystalline parts that do not have the c-axis orientation. The CAAC-OS film exhibits a peak at 2θ of around 31° and a peak at 2θ of around 36°. It is preferable that no peaks are present nearby.

[0179] The CAAC-OS film is an oxide semiconductor film with a low concentration of impurities. The oxide semiconductor film is made of an element other than the main component, such as silicon or a transition metal element. The elements such as ZnO, which have stronger bonding strength with oxygen than the metal elements constituting the oxide semiconductor film, By removing oxygen from the oxide semiconductor film, the atomic arrangement of the oxide semiconductor film is disrupted, and the crystallinity is reduced. In addition, heavy metals such as iron and nickel, argon, and carbon dioxide are Because the diameter (or molecular radius) is large, when the molecule is contained inside the oxide semiconductor film, The impurities contained in the oxide semiconductor film are likely to disturb the atomic arrangement of the oxide semiconductor film, which may result in a decrease in crystallinity. The pure material may act as a carrier trap or a carrier generation source.

[0180] The CAAC-OS film is an oxide semiconductor film with a low density of defect states. Oxygen vacancies in semiconductor films can act as carrier traps and trap hydrogen. This can become a carrier generation source.

[0181] The low impurity concentration and low defect level density (low oxygen vacancies) are called high-purity intrinsic or The term "high-purity intrinsic" refers to a substantially high-purity intrinsic oxide semiconductor. Since the film has a small number of carrier generation sources, the carrier density can be reduced. The transistor using the oxide semiconductor film has electrical characteristics (noise) such that the threshold voltage is negative. It is also called "marine.") It is rare for it to become pure or substantially pure. An intrinsic oxide semiconductor film has few carrier traps. Transistors using this film have little fluctuation in electrical characteristics and are highly reliable. Note that it takes time for the charges trapped in the carrier traps in the oxide semiconductor film to be released. The time is long and the charge may behave as if it is fixed. Therefore, a transistor using an oxide semiconductor film with a high density of defect states has unstable electrical characteristics. This may be the case.

[0182] In addition, the electrical characteristics of transistors using CAAC-OS films are improved by irradiation with visible light or ultraviolet light. There is little gender variation.

[0183] <Single-crystal oxide semiconductor> The single-crystal oxide semiconductor film has a low impurity concentration and a low density of defect states (few oxygen vacancies). ) oxide semiconductor film. Therefore, the carrier density can be reduced. A transistor using a crystalline oxide semiconductor film rarely has normally-on electrical characteristics. Furthermore, since the single-crystal oxide semiconductor film has a low impurity concentration and a low density of defect states, Therefore, in the case of a transistor using a single-crystal oxide semiconductor film, the number of carrier traps may be reduced. The transistor has small fluctuations in electrical characteristics and is highly reliable.

[0184] Note that the oxide semiconductor film has a high density when it has few defects. High crystallinity increases density. In addition, the oxide semiconductor film has a low concentration of impurities such as hydrogen. The density of a single-crystal oxide semiconductor film is higher than that of a CAAC-OS film. The CAAC-OS film has a higher density than the microcrystalline oxide semiconductor film. The conductor film has a higher density than the microcrystalline oxide semiconductor film. The density is higher than that of an crystalline oxide semiconductor film.

[0185] <Polycrystalline oxide semiconductor> In the polycrystalline oxide semiconductor film, crystal grains can be confirmed by high-resolution TEM observation. The crystal grains contained in the polycrystalline oxide semiconductor film can be observed, for example, by high-resolution TEM. In the observation image, 2nm to 300nm, 3nm to 100nm, or 5nm to 50nm In addition, polycrystalline oxide semiconductor films are often characterized by grain sizes of 100 μm or less using high-resolution TEM. In some cases, grain boundaries can be identified in the observed image.

[0186] The polycrystalline oxide semiconductor film has a plurality of crystal grains, and the crystal orientation between the plurality of crystal grains is In addition, when an XRD device is used for a polycrystalline oxide semiconductor film, When structural analysis is performed, for example, the out of polycrystalline oxide semiconductor film having InGaZnO4 crystals In the t-of-plane analysis, there is a peak at 2θ around 31° and a peak at 2θ around 36°. peak or other peaks may appear.

[0187] A polycrystalline oxide semiconductor film has high crystallinity and therefore may have high electron mobility. Therefore, a transistor using a polycrystalline oxide semiconductor film has high field-effect mobility. However, in a polycrystalline oxide semiconductor film, impurities may segregate at the grain boundaries. The grain boundaries of the polycrystalline oxide semiconductor film become defect states. Since the oxide semiconductor film may become a carrier trap or a carrier generation source, The transistors using the CAAC-OS film showed a small change in electrical characteristics compared to the transistors using the CAAC-OS film. may result in a transistor with low reliability.

[0188] <Microcrystalline oxide semiconductor> In the microcrystalline oxide semiconductor film, crystal parts can be clearly seen in the TEM image. The crystal parts contained in the microcrystalline oxide semiconductor film may have a size of 1 nm or more and 100 nm or more. In particular, the size of the particles is between 1 nm and 10 nm. Nanocrystals (nc) are microcrystals with a diameter of 1 nm or less, or 1 nm to 3 nm. The oxide semiconductor film having nc-OS (nanocrystalline O The nc-OS film is called an oxide semiconductor film. In EM observation images, the grain boundaries may not be clearly visible.

[0189] The nc-OS film is a microscopic region (e.g., a region of 1 nm to 10 nm, especially a region of 1 nm or less). The nc-OS film has a periodic atomic arrangement in the region of 3 nm or less. There is no regularity in the crystal orientation between the crystal parts, and therefore no orientation is observed throughout the film. Therefore, the nc-OS film cannot be distinguished from an amorphous oxide semiconductor film depending on the analytical method. For example, XRD, which uses X-rays with a diameter larger than that of the crystal part, is used for nc-OS films. When structural analysis is performed using the device, the crystal plane is analyzed using the out-of-plane method. In addition, the peaks indicating the crystal grains with a diameter larger than that of the crystalline part (e.g., When electron beam diffraction (also called selected area electron beam diffraction) is performed using an electron beam of 50 nm or more, On the other hand, for the nc-OS film, the crystalline The probe diameter is close to the size of the crystal part or smaller than the crystal part (for example, 1 nm to 30 nm). When electron beam diffraction using a sagittal beam (also called nanobeam electron diffraction) is performed, spots are observed. Furthermore, when nanobeam electron diffraction is performed on the nc-OS film, circular patterns (ripples) are observed. In addition, nanobeams on the nc-OS film may be observed. When electron diffraction is performed, multiple spots may be observed within the ring-shaped region.

[0190] The nc-OS film is an oxide semiconductor film with higher order than an amorphous oxide semiconductor film. Therefore, the nc-OS film has a lower density of defect states than the amorphous oxide semiconductor film. In the nc-OS film, there is no regularity in the crystal orientation between different crystal parts. The OS film has a higher density of defect states than the CAAC-OS film.

[0191] <Variation 1, Regarding the Undercoat Insulating Film> In the transistor described in this embodiment, the substrate 101 and the gate electrode may be formed as needed. A base insulating film can be provided between the conductive films 103 which function as the insulating film. Silicon oxide, silicon oxynitride, silicon nitride, silicon nitride oxide, gallium oxide hafnium oxide, yttrium oxide, aluminum oxide, aluminum oxide nitride, etc. The base insulating film can be formed using silicon nitride, gallium oxide, By forming it using hafnium oxide, yttrium oxide, aluminum oxide, etc., the substrate Impurities, typically alkali metals, water, hydrogen, etc., diffuse from 101 to the metal oxide film 109a. This can suppress dispersion.

[0192] The base insulating film can be formed by a sputtering method, a CVD method, or the like.

[0193] <Modification 2: Gate insulating film> The insulating film 105 formed of a nitride insulating film is replaced with a first nitride insulating film having fewer defects and a water The gate insulating film can be formed as a laminated structure of a second nitride insulating film having high electron blocking properties. By providing a nitride insulating film with few defects as the film, the dielectric strength of the gate insulating film is improved. In addition, a nitride insulating film with high hydrogen blocking properties can be used as a gate insulating film. By providing the insulating film 105, hydrogen from the conductive film 103 which functions as a gate electrode and the insulating film 105 can be Therefore, it is possible to prevent the metal oxide film 109a from moving thereto.

[0194] Alternatively, the insulating film 105 may be formed of a nitride insulating film having high impurity blocking properties. The first nitride insulating film has a low defect content, the second nitride insulating film has a low defect content, and the second nitride insulating film has a high hydrogen blocking property. A second nitride insulating film is laminated in this order from the conductive film 103 side which functions as a gate electrode. As the gate insulating film, a first insulating film having a high impurity blocking property can be used. By providing the nitride insulating film 1, impurities from the conductive film 103 functioning as a gate electrode are prevented. Typically, hydrogen, nitrogen, alkali metal, alkaline earth metal, etc. are added to the metal oxide film 1. This can prevent the device from moving to 09a.

[0195] Note that the structures and methods described in this embodiment may be different from the structures and methods described in other embodiments. They can be used in appropriate combination.

[0196] (Embodiment 2) In this embodiment mode, a method for manufacturing an element substrate of a display device, which is different from that in Embodiment Mode 1, will be described. In this embodiment, as in the first embodiment, a metal oxide semiconductor having a channel region is used. A metal oxide film and an insulating film that functions as a channel protection film are formed using a single photomask. On the other hand, in this embodiment, a conductive film that functions as an electrode and a dielectric film of a capacitance element are used. The order of steps for forming a functional insulating film is different from that in the first embodiment.

[0197] A specific example of an element substrate of a liquid crystal display device using liquid crystal elements for the pixels 13 will be described. Here, a top view of the pixel 13 shown in FIG. 1(B) is shown in FIG.

[0198] In FIG. 6, the conductive film 203 functioning as a scanning line is oriented in a direction substantially perpendicular to the signal line ( The conductive film 213a that functions as a signal line is provided so as to extend in the horizontal direction. The conductive film is provided so as to extend in a direction substantially perpendicular to the capacitor line (the vertical direction in the drawing). The conductive film 213c is provided so as to extend in a direction parallel to the signal line. The conductive film 203 is electrically connected to the scanning line driver circuit 14 (see FIG. 1(A)). The conductive film 213a functioning as a signal line and the conductive film 213c functioning as a capacitance line are , and is electrically connected to a signal line driving circuit 16 (see FIG. 1(A)).

[0199] The transistor 22a is provided in the area where the scanning line and the signal line intersect. The gate electrode 22a includes a conductive film 203 that functions as a gate electrode, a gate insulating film (not shown in FIG. 6), and a gate insulating film 204. ), a metal oxide film 209a in which a channel region is formed on the gate insulating film, The gate electrode 213 is made up of conductive films 213a and 213b which function as a source electrode and a drain electrode. The conductive film 203 also functions as a scan line, and the region overlapping with the metal oxide film 209a is The conductive film 213a functions as a gate electrode of the transistor 22a. The region overlapping with the metal oxide film 209a is connected to the source electrode of the transistor 22a. In FIG. 6, the scanning lines are arranged at the ends of the top surface. The scanning lines are located outside the edge of the metal oxide film 209a. As a result, the gold contained in the transistor The metal oxide film 209a is not irradiated with light, and fluctuations in the electrical characteristics of the transistor can be suppressed. can.

[0200] The conductive film 213b has a light-transmitting property and functions as a pixel electrode in the opening 219. The conductive film 221 is electrically connected to the conductive film 221 .

[0201] The capacitance element 25a is formed by a metal oxide film 209b formed on the gate insulating film and a pixel electrode. a light-transmitting conductive film 221 that functions as a gate insulating film; and a nitride film provided over the transistor 22a. The metal oxide film 109b is made of a dielectric film formed of an insulating film. Therefore, the capacitor 25a has a light-transmitting property. The metal oxide film 209b functioning as a capacitance line is connected to the conductive film 213c functioning as a capacitance line. are.

[0202] Since the capacitance element 25a has light-transmitting properties, the capacitance element 25a can be arranged large within the pixel 13. Therefore, it is possible to increase the aperture ratio, preferably to 50% or more. It is possible to increase the charge capacity to about 55% or more, preferably 60% or more. For example, a semiconductor device with high resolution, such as a liquid crystal display, can be obtained. In a display device, the area of ​​a pixel is reduced, and the area of ​​a capacitance element is also reduced. In a semiconductor device with high resolution, the charge capacity stored in the capacitance element becomes small. However, since the capacitor 25a shown in this embodiment has a light-transmitting property, the capacitor By providing the pixel electrodes at , it is possible to obtain a sufficient charge capacity in each pixel while increasing the aperture ratio. Typically, pixel densities are 200ppi or higher, even 300ppi or higher, and even 50ppi or higher. The present invention can be suitably used for high-resolution semiconductor devices with a resolution of 0 ppi.

[0203] 6, the pixel 13 has a side parallel to the conductive film 203 that functions as a scanning line. The side parallel to the conductive film 213a functioning as a signal line is shorter than the side parallel to the conductive film 213a. The conductive film 213c functioning as a signal line is parallel to the conductive film 213a functioning as a signal line. As a result, the area of ​​the conductive film 213c in the pixel 13 is reduced. This makes it possible to increase the aperture ratio.

[0204] Furthermore, according to one embodiment of the present invention, the aperture ratio can be increased even in a high-resolution display device. This allows for efficient use of light from light sources such as backlights, and reduces the power consumption of the display device. The force can be reduced.

[0205] Next, using the cross-sectional views of the dashed and dotted lines AB and CD shown in Figure 6, A method for manufacturing the element substrate of the device will be described.

[0206] Through the same steps as in the first embodiment, a first photomask and a second photomask are used. By this process, a conductive film that functions as a gate electrode is formed on the substrate 210 as shown in FIG. Further, insulating films 205 and 207a are formed on the substrate 291 and the conductive film 203. , 207b are formed on the insulating films 207a and 207b. 9a and 209b are formed on the metal oxide film 209a. An insulating film 211c is formed on the insulating film 211. After that, a heat treatment is performed.

[0207] The substrate 201 can be appropriately selected from the substrate 101 shown in the first embodiment. The conductive film 203 is made of the same material as the conductive film 103 which functions as a gate electrode in Embodiment 1. The insulating film 205 can be formed by any of the insulating films shown in Embodiment 1. The insulating films 207a and 207b can be made of the same material and by the same method as those for the insulating film 105. The insulating films 107a and 107b are formed by appropriately selecting the same material and manufacturing method as those of the insulating films 107a and 107b described in Embodiment 1. The metal oxide films 209a and 209b may be selected from the metal oxide films shown in Embodiment 1. The same materials and manufacturing methods as those for the thin films 109a and 109b can be appropriately selected. The insulating film 211c, which functions as a protective film, is the same as the insulating film 111c shown in the first embodiment. The material and manufacturing method can be selected appropriately.

[0208] In the etching process for forming the insulating film 211c, the metal oxide film 209 In a and 209b, the area exposed to the plasma is damaged and oxygen vacancies are formed. Therefore, the area of ​​the metal oxide film 209a that is not covered with the insulating film 211c, and The conductivity of the metal oxide film 209b increases.

[0209] Next, as shown in FIG. 7(B), the insulating film 205, the insulating films 207a and 207b, and the metal oxide film are A conductive film 212 is formed on the conductive films 209a and 209b and the insulating film 211c. A mask 23 is formed on the conductive film 212 by a photolithography process using the photomask 3. 1a, 231b, and 231c.

[0210] The conductive film 212 can be formed by appropriately selecting a material and a manufacturing method similar to those of the conductive film 116 described in Embodiment 1. You can choose.

[0211] Next, a part of the conductive film 212 is etched using masks 231a, 231b, and 231c. The conductive films 213a and 213b function as a pair of electrodes, and the conductive film 213b functions as a capacitance line. A film 213c is formed by dry etching or / and wet etching. The conductive film 116 can be etched. 231c is removed (see FIG. 7(C)).

[0212] Next, as shown in FIG. 8(A), the insulating film 205, the insulating films 207a and 207b, and the metal oxide film are On the insulating films 209a and 209b, the insulating film 211c, and the conductive films 213a, 213b, and 213c Next, a photolithography process using a fourth photomask is performed to form an insulating film 214. By this process, a mask 233 is formed on the insulating film 214 .

[0213] The insulating film 214 can be formed by appropriately selecting a material and a formation method similar to those of the insulating film 112 described in Embodiment 1. You can choose.

[0214] Plasma damage occurs when forming the insulating film 214 on the insulating film 211c, causing metal Oxygen vacancies are formed in the oxide films 209a and 209b. 9a, the area not covered with the insulating film 211c and the conductive metal oxide film 209b. In addition, by using a nitride insulating film containing hydrogen as the insulating film 214, the insulating Hydrogen diffuses from the film 214 to the metal oxide films 209a and 209b. Hydrogen moves to the oxygen vacancies. As a result, the metal oxide film 209b becomes conductive. The metal oxide film 209c has high conductivity. 9 c functions as one electrode of the capacitor element 25 .

[0215] The metal oxide film 209a is in contact with the insulating film 213 on the outside of the insulating film 211c. Since the insulating film 211c is an oxide insulating film, the metal oxide film 20 in contact with the insulating film 211c The metal oxide film 209a functions as a channel region of the transistor. The region in contact with the conductive films 213a and 213b is conductive like the metal oxide film 209c. That is, the metal oxide film 209a functions as a low resistance region. Therefore, it is possible to increase the on-state current of the transistor and also to improve the field effect mobility. It is possible to increase it.

[0216] The nitride insulating film also functions as a blocking film for water, hydrogen, and the like. 14, a nitride insulating film is provided, and hydrogen and water are prevented from entering the metal oxide film 209a from the outside. It is possible to prevent intrusions such as

[0217] Both the metal oxide film 209a and the metal oxide film 209c are formed on the gate insulating film. However, the impurity concentration is different. For example, the hydrogen concentration in the metal oxide film 209a is 5 x10 19 atoms / cm 3 Less than 5 x 10 18 atoms / cm 3 less than, Preferably 1 x 10 18 atoms / cm 3 Less than or equal to 5 × 10 17 atom s / cm 3 or less, more preferably 1 × 10 16 atoms / cm 3 The metal acid The hydrogen concentration in the oxide film 209c is 8×10 19 or more, preferably 1 × 10 20 at oms / cm 3 More preferably, 5 × 10 20 The above is the case. The hydrogen concentration in the metal oxide film 209c is twice as high, preferably 10 times or more as high as that in the metal oxide film 209a. Above.

[0218] The metal oxide film 209c has a lower resistivity than the metal oxide film 209a. The resistivity of the film 209c is 1×10 -8 more than 1x10 - 1 It is preferable that the ratio is 1×10 or less, typically 1×10 -3 Ωcm or more 1×10 4 Ωcm not yet More preferably, the resistivity is less than 1×10 -3 Ωcm or more 1×10 -1 Less than Ωcm It is good.

[0219] Next, a heat treatment may be performed. The temperature of the heat treatment is typically 150° C. or higher and 40° C. or lower. 0°C or lower, preferably 300°C or higher and 400°C or lower, preferably 320°C or higher and 370°C or lower Let's say.

[0220] The insulating film 205 formed of a nitride insulating film and the insulating film 214 formed of a nitride insulating film are The insulating films 205 and 214 are in contact with each other, and the metal oxide film 209a and the insulating film 211c are disposed between the insulating films 205 and 214. The nitride insulating film has a small diffusion coefficient of hydrogen, water, and oxygen, and is resistant to hydrogen, water, and oxygen. The insulating film 211c has a high blocking property against oxygen. By forming the insulating film using an oxide insulating film containing more oxygen than silicon, As a result, the oxygen contained in the metal oxide film 209a can be prevented from diffusing to the outside. As a result, oxygen deficiency in the metal oxide film 209a can be reduced. Therefore, the diffusion of hydrogen, water, etc. into the metal oxide film 209a can be suppressed. As a result, the amount of hydrogen and water in the conductive film 209a can be reduced. It is possible to create a

[0221] Next, as shown in FIG. 8(A), a photolithography process using a fourth photomask is performed. Then, a mask 233 is formed by etching a part of the insulating film 214 using the mask 233. 8B, an insulating film 217 having an opening 219 is formed. In the opening 219, a part of the conductive film 213b is exposed.

[0222] Next, as shown in FIG. 8C, a light-transmitting film is formed on the exposed portion of the conductive film 213b and the insulating film 217. Next, a conductive film 220 having a high conductivity is formed by photolithography using a fifth photomask. A mask 235 is formed on the conductive film 220 by a film process.

[0223] The conductive film 220 can be formed by appropriately selecting a material and a manufacturing method similar to those of the conductive film 118 described in Embodiment 1. You can choose.

[0224] Next, a part of the conductive film 220 is etched using a mask 235 to form a film that functions as a pixel electrode. After that, the mask 235 is removed (see FIG. 8(D)). .).

[0225] Through the above steps, the conductive film 203 functioning as a gate electrode and the gate insulating film The insulating films 205 and 206a, the metal oxide film 209a, and a part of the metal oxide film 209a are covered with the insulating films 205 and 206a. The insulating film 211c functions as a channel protection film, and is in contact with the metal oxide film 209a. The transistor 22a having the conductive films 213a and 213b functioning as electrodes is fabricated. In addition, the conductive film 213b included in the transistor 22a is in contact with the conductive film 213b and serves as a pixel electrode. In addition, a conductive film 221 formed on the insulating film 206b can be formed. A capacitor element 25a having a metal oxide film 209c, an insulating film 217, and a conductive film 221 is fabricated. That is, the transistor 22a, the conductive film 221 functioning as a pixel electrode, The element substrate having the capacitor element 25a can be manufactured using five photomasks. In this embodiment mode, the metal oxide film and the channel protective film are formed using one photomask. Therefore, the number of photomasks required for manufacturing the element substrate can be reduced.

[0226] In addition, the semiconductor device described in this embodiment has a metal oxide film including a channel region of a transistor. At the same time as forming the metal oxide film, a metal oxide film that will become one of the electrodes of the capacitance element is formed. A metal oxide film including a channel region of a capacitor and a metal oxide film that will be one of the electrodes of a capacitor element. The conductive film that functions as a pixel electrode is made of the same metal element as the capacitor element. For this reason, a new conductive film is formed to form a capacitor element. Since the step of forming a capacitor is not required, the manufacturing steps of the display device can be reduced. Since both the metal oxide film 109c and the conductive film 119, which are electrodes, have light-transmitting properties, As a result, the area occupied by the capacitor element is increased while the aperture ratio of the pixel is increased. Furthermore, a display device with reduced power consumption can be manufactured. .

[0227] Note that the structures and methods described in this embodiment may be different from the structures and methods described in other embodiments. They can be used in appropriate combination.

[0228] (Embodiment 3) In this embodiment, the number of defects in the metal oxide film is smaller than that in the first and second embodiments. A semiconductor device having a transistor capable of further reducing the The transistor described in this embodiment has a structure similar to that of the transistors in Embodiments 1 and 2. In comparison, a multilayer film having a plurality of metal oxide films is provided instead of the metal oxide film. The points are different.

[0229] FIG. 9 is a cross-sectional view of a transistor 22b and a capacitor 25b included in the semiconductor device. FIG. 9 is a cross-sectional view taken along the dashed line AB and CD in FIG.

[0230] The transistor 22b shown in FIG. 9A has a multilayer film 150a on an insulating film 107a. The multilayer film 150a includes a first metal oxide film 151a in contact with the insulating film 107a, and a first The metal oxide film 151a and the second metal oxide film 152a are in contact with the insulating film 111c. do.

[0231] The capacitor element 25b shown in FIG. 9A has a multilayer film 150b on an insulating film 107b. The layer film 150b is made up of a first metal oxide film 151b in contact with the insulating film 107b and a first metal oxide film 151b. The second metal oxide film 152b is in contact with the oxide film 151b and the insulating film 113.

[0232] The second metal oxide films 152a and 152b are formed by bonding the first metal oxide films 151a and 151b together. It is a metal oxide film composed of one or more constituent elements. At the interfaces between the metal oxide films 151a and 151b and the second metal oxide films 152a and 152b, Therefore, the movement of carriers is not hindered at the interface, The field effect mobility of the transistor is increased.

[0233] The first metal oxide films 151a and 151b and the second metal oxide films 152a and 152b are Representative examples include In-Ga oxide, In-Zn oxide, and In-M-Zn oxide (M is Al). , Ga, Ti, Y, Zr, La, Ce, or Nd).

[0234] The second metal oxide films 152a and 152b are formed on the first metal oxide films 151a and 151b. The energy of the bottom of the conduction band is closer to the vacuum level than 1b, and is typically a second metal oxide. The energy of the bottom of the conduction band of the first metal oxide films 151a and 151b is The difference in energy between the lower end of the conduction band of 51b and the lower end of the conduction band of 51b is 0.05 eV or more, 0.07 eV or more, or 0 0.1eV or more, or 0.15eV or more and 2eV or less, 1eV or less, 0.5eV or less , or 0.4 eV or less. That is, the electron affinity of the second metal oxide films 152a and 152b is The difference between the electron affinity of the first metal oxide film 151a and the electron affinity of the first metal oxide film 151b is 0.05 eV or less. above, 0.07 eV or more, 0.1 eV or more, or 0.15 eV or more and 2 eV or less, 1 eV or less, 0.5 eV or less, or 0.4 eV or less.

[0235] The first metal oxide films 151a and 151b and the second metal oxide films 152a and 152b are The inclusion of In is preferable because it increases carrier mobility (electron mobility).

[0236] The second metal oxide films 152a and 152b may be made of Al, Ga, Ti, Y, Zr, La, Having Ce or Nd in a higher atomic ratio than In may have the following effects: (1) The energy gap of the second metal oxide films 152a and 152b is increased. (2) The electron affinity of the second metal oxide films 152a and 152b is reduced. (3) From the outside (4) Compared to the first metal oxide films 151a and 151b, the diffusion of impurities from the first metal oxide films 151a and 151b is suppressed. (5) Al, Ga, Y, Zr, La, Ce, or Nd reacts with oxygen Since it is a metal element with a strong bonding force, oxygen deficiency is unlikely to occur.

[0237] When the first metal oxide films 151a and 151b are In-M-Zn oxides, In and When the sum of In and M is 100 atomic %, the atomic ratio of In to M is preferably 25 atomic % or more and M is less than 75 atomic %, and more preferably In is 34 atomic % or more and M is less than 66 atomic %.

[0238] When the second metal oxide films 152a and 152b are In-M-Zn oxides, In and When the sum of In and M is 100 atomic %, the atomic ratio of In to M is preferably I n is less than 50 atomic % and M is greater than 50 atomic %, more preferably Assume that In is less than 25 atomic % and M is greater than 75 atomic %.

[0239] In addition, the first metal oxide films 151a and 151b and the second metal oxide films 152a and 15 2b is In-M-Zn oxide M (M is Al, Ga, Ti, Y, Zr, La, Ce, or In the case of Nd, the second metal oxide film is thicker than the first metal oxide film 151a, 151b. M (Al, Ga, Ti, Y, Zr, La, Ce, or The atomic ratio of Nd) is large, and typically, the first metal oxide films 151a and 151b contain It is 1.5 times or more, preferably 2 times or more, and more preferably 3 times as large as the atoms contained in the above-mentioned This is a high atomic ratio.

[0240] In addition, the first metal oxide films 151a and 151b and the second metal oxide films 152a and 15 2b is In-M-Zn oxide (M is Al, Ga, Ti, Y, Zr, La, Ce, or In the case of Nd), the second metal oxide films 152a and 152b are formed of In:M:Zn=x1:y1: z1 [atomic ratio], the first metal oxide films 151a and 151b are In:M:Zn=x2:y 2:z2 [atomic ratio], y1 / x1 is larger than y2 / x2, and preferably, y 1 / x1 is 1.5 times or more than y2 / x2. More preferably, y1 / x1 is 1.5 times or more than y2 / x2, and more preferably, y1 / x1 is three times larger than y2 / x2 In this case, when y2 is equal to or larger than x2 in the metal oxide film, the metal oxide film This is preferable because it can provide stable electrical characteristics to the transistor 22b using this material.

[0241] The first metal oxide films 151a and 151b are made of In-M-Zn oxide (M is Al, Ga, In the case of Ti, Y, Zr, La, Ce, or Nd), the first metal oxide film 151a, 15 In the target used to form 1b, the atomic ratio of metal elements is In:M:Zn If we set =x1:y1:z1 、 x1 / y1 is between 1 / 3 and 6, or between 1 and 6 and z1 / y1 is preferably 1 / 3 or more and 6 or less, and more preferably 1 or more and 6 or less. By setting z1 / y1 to 1 or more and 6 or less, the first metal oxide films 151a and 151b can be formed. The CAAC-OS film is easily formed as 1b. Typical examples are In:M:Zn=1:1:1, In:M:Zn=1:1:1.2, In :M:Zn=3:1:2 etc.

[0242] The second metal oxide films 152a and 152b are made of In-M-Zn oxide (M is Al, Ga, In the case of Ti, Y, Zr, La, Ce, or Nd), the second metal oxide film 152a, 15 In the target used to form 2b, the atomic ratio of metal elements is In:M:Zn If we set =x2:y2:z2 、 x2 / y2 <x1 / y1であって、z2 / y2は、1 / 3 It is preferable that z2 / y2 is 1 or more and 6 or less, and more preferably 1 or more and 6 or less. By the following, CAAC-OS films are formed as the second metal oxide films 152a and 152b. A typical example of the atomic ratio of the target metal elements is In:M:Zn. =1:3:2, In:M:Zn=1:3:4, In:M:Zn=1:3:6, In:M: Zn=1:3:8, etc.

[0243] The first metal oxide films 151a and 151b and the second metal oxide films 152a and 15 The atomic ratio of 2b is subject to a margin of error of plus or minus 40% from the atomic ratio above. include.

[0244] The second metal oxide films 152a and 152b are formed as a result of the formation of the film that will become the insulating film 111c. It also functions as a film for reducing damage to the first metal oxide film 151a.

[0245] The thickness of the first metal oxide films 151a and 151b is preferably 3 nm or more and 200 nm or less. The thickness is preferably 3 nm or more and 100 nm or less, and more preferably 3 nm or more and 50 nm or less. The thickness of the metal oxide films 152a and 152b is 3 nm or more and 100 nm or less, preferably 3 nm or more and 50 nm.

[0246] The first metal oxide films 151a and 151b and the second metal oxide films 152a and 152b are For example, the non-single crystal structure may be a CAAC-OS (C Axis Aligned-Crystalline Oxide Semiconductor uctor), polycrystalline structure, microcrystalline structure (described below), or amorphous structure.

[0247] The first metal oxide films 151a and 151b and the second metal oxide films 152a and 15 In 2b, there are amorphous structure regions, microcrystalline structure regions, polycrystalline structure regions, and CAAC-O A mixed film having two or more of the S region and the single crystal structure region may be formed. For example, amorphous structure regions, microcrystalline structure regions, polycrystalline structure regions, CAAC-OS regions In some cases, the crystal structure may be a single layer structure having two or more regions of either a single crystal structure or a mixed structure. The composite film may have, for example, an amorphous structure region, a microcrystalline structure region, a polycrystalline structure region, a CAAC- It may have a layered structure of two or more regions, either an OS region or a single crystal structure region. .

[0248] Here, a second metal oxide film is formed between the first metal oxide film 151a and the insulating film 111c. Therefore, the second metal oxide film 152a and the insulating film 111c Even if carrier traps are formed by impurities and defects during There is a gap between the area where the wrap is formed and the first metal oxide film 151a. As a result, electrons flowing through the first metal oxide film 151a are less likely to be captured by the carrier traps. It is possible to increase the on-current of the transistor 22b and also to improve the field effect mobility. Furthermore, when an electron is captured in a carrier trap, the electron is transferred to a negative fixed charge. As a result, the threshold voltage of the transistor fluctuates. However, there is a gap between the first metal oxide film 151a and the region where carrier traps are formed. Therefore, it is possible to suppress the capture of electrons in the carrier traps, and the threshold This can reduce fluctuations in the value voltage.

[0249] In addition, the second metal oxide film 152a can block impurities from the outside. Therefore, it is possible to reduce the amount of impurities that move from the outside to the first metal oxide film 151a. Furthermore, oxygen vacancies are less likely to form in the second metal oxide film 152a. It is possible to reduce the impurity concentration and oxygen vacancy amount in the first metal oxide film 151a. be.

[0250] The first metal oxide films 151a and 151b and the second metal oxide films 152a and 15 2b is a continuous junction (in particular, the energy at the bottom of the conduction band) rather than simply stacking each film. The structure is such that the thickness of each film changes continuously. There are no impurities at the interface that can form defect levels such as trap centers or recombination centers. The laminated structure is as follows. When impurities are present between the metal oxide films 152a and 152b, the energy band The continuity of the interface is lost, and carriers are trapped or recombined at the interface and disappear. cormorant.

[0251] To form continuous junctions, a multi-chamber deposition system equipped with a load lock chamber is required. Each film is laminated in succession using a sputtering device without being exposed to the atmosphere. Each chamber in the sputtering equipment is indispensable for the metal oxide film. An adsorption type vacuum pump such as a cryopump is used to remove as much water as possible. High vacuum pumping (5×10 -7 Pa~1×10 -4 It is preferable to Alternatively, a turbomolecular pump and cold trap can be combined to evacuate the chamber from the exhaust system. It is preferable to prevent gases, especially gases containing carbon or hydrogen, from flowing back into the .

[0252] As shown in FIG. 9B, the transistor 22c has a multilayer film 155a. The element 25c may have a multilayer film 155b.

[0253] The multilayer film 155a includes a third metal oxide film 153a, a first metal oxide film 151a, and A second metal oxide film 152a is laminated on the first metal oxide film 152a. A third metal oxide film 153a is laminated on the second metal oxide film 152a. The first metal oxide film 152a is in contact with the insulating film 111c, and the second metal oxide film 152b is in contact with the insulating film 111c. The metal oxide film 151a functions as a channel region.

[0254] The multilayer film 155b includes a third metal oxide film 153b, a first metal oxide film 151b, and The second metal oxide film 152b is laminated in this order. The third metal oxide film 153b is laminated in this order. The second metal oxide film 152b is in contact with the insulating film 107b, and the second metal oxide film 152b is in contact with the insulating film 113.

[0255] The third metal oxide films 153a and 153b are formed in a layer similar to the second metal oxide films 152a and 152b. Similar materials and forming methods can be used as appropriate.

[0256] The third metal oxide films 153a and 153b are thicker than the first metal oxide films 151a and 151b. The thickness of the third metal oxide films 153a and 153b is preferably 1 nm or more. By making the thickness 5 nm or less, preferably 1 nm or more and 3 nm or less, the threshold voltage of the transistor can be reduced. It is possible to reduce the amount of pressure fluctuation.

[0257] The transistor described in this embodiment has an insulating film 107a and a first metal oxide film 151a. The third metal oxide film 153a is provided between the first metal oxide film 15 A second metal oxide film 152a is provided between the insulating film 111a and the insulating film 111c. Therefore, the insulating film 107a and the first metal oxide film 151a are separated from each other. Carrier traps are formed between the film 151a and the insulating film 111c due to impurities and defects. Even if the carrier traps are formed, the area where the carrier traps are formed and the first metal oxide film 151a As a result, the electrons flowing through the first metal oxide film 151a become carriers. It is difficult to be captured by a trap, and the on-current of the transistor 22c can be increased. In addition, the field effect mobility can be increased. When this happens, the electrons become negative fixed charges. However, the first metal oxide film 151a and the carrier traps The gap between the formed region suppresses the capture of electrons in the carrier trap. This makes it possible to reduce the fluctuation in the threshold voltage of the transistor 22c. do.

[0258] Note that the structures and methods described in this embodiment may be different from the structures and methods described in other embodiments. They can be used in appropriate combination.

[0259] (Fourth embodiment) In this embodiment, the on-state current is large, the field effect mobility is high, and the variation in electrical characteristics is small. A method for manufacturing a small number of transistors and capacitors by reducing the number of photomasks is described. 10 and 11. In this embodiment, the transistor shown in the second embodiment is used. Although the present embodiment will be described using a transistor and a manufacturing method thereof, the present embodiment will be applied to other embodiments as appropriate. Furthermore, the description of the configuration that overlaps with the second embodiment will be omitted.

[0260] 10 is a top view of the pixel 13, and FIG. 11(A) shows the pixel 13 along the dashed lines AB and CD in FIG. 11(A) is a cross-sectional view taken along the dashed line EF in FIG. 10, and FIG. 11(B) is a cross-sectional view taken along the dashed line EF in FIG.

[0261] The transistor 22d is provided in the area where the scanning line and the signal line intersect. The gate electrode 22d is made up of a conductive film 203 which functions as a gate electrode, a gate insulating film (not shown in FIG. 11), ), a metal oxide film 209a in which a channel region is formed on the gate insulating film, Conductive films 213a and 213b functioning as source and drain electrodes, and a metal oxide film 2 11. The insulating film (not shown in FIG. 11) covers the conductive films 213a and 213b ... The transistor 22d is formed by the conductive film 243 which functions as an electrode. In the above, the conductive film 203 and the conductive film 243 functioning as gate electrodes are connected to each other. It is characterized by:

[0262] Next, the cross-sectional structure of the transistor 22d will be described with reference to FIG. ) is a cross-sectional view of the transistor 22d in the channel length direction and a cross-sectional view of the capacitor 25a, FIG. 11B is a cross-sectional view of the transistor 22d in the channel direction.

[0263] The transistor 22d shown in FIGS. 11A and 11B is a channel protection type transistor. A conductive film 203 serving as a gate electrode is provided on a substrate 201. An insulating film 205 formed on the plate 201 and the conductive film 203, and a The insulating film 207a and the metal oxide film overlapping the conductive film 203 via the insulating films 205 and 207a. and an insulating film 209a formed on the metal oxide film 209a, which functions as a channel protection film. One end of the insulating film 211c is located on the insulating film 211c and is connected to the metal oxide film 209a. The insulating film 205, the metal oxide film 209a, and the conductive film 213a are connected to each other. an insulating film 211c, an insulating film 217 formed on the conductive films 213a and 213b; The insulating film 205 has a conductive film 243 that functions as a gate electrode formed on the insulating film 217. The insulating film 211c and the insulating film 207a function as gate insulating films. 17 functions as a gate insulating film.

[0264] As shown in FIG. 11B, the conductive film 203 and the conductive film 243 are formed on the insulating film 205 and the insulating film 243. The connection is made at an opening 241 in the film 217. In the width direction, the end of the conductive film 243 is located outside the end of the metal oxide film 209a. The side surface of the metal oxide film 209a faces the conductive film 243 with the insulating film 217 interposed therebetween. The conductive film 243 faces the side surface of the metal oxide film 209a in the opening 241. .

[0265] The conductive film 243 can be formed using a material and a manufacturing method similar to those of the conductive film 221. Furthermore, the opening 241 can be formed at the same time as the opening 219 is formed. As a result, transistors can be manufactured using five photomasks without increasing the number of photomasks. A heater 22d can be produced.

[0266] In FIG. 11B, the conductive film 203 and the conductive film 243 are directly connected to each other. On the other hand, as shown in FIG. 11C, the conductive film 203 and the conductive film 243 are The electrodes may be electrically connected via a

[0267] That is, in the opening 251 provided in the insulating film 205, the conductive film 203 and the conductive film 253 is connected to the insulating film 217. 53 and the conductive film 243 are connected. As a result, the conductive film 203 and the conductive film 253 have the same potential. This is a structure in which a voltage of

[0268] The conductive film 253 is formed using a material and a manufacturing method similar to those of the conductive films 213a and 213b. In comparison with the opening 241 shown in FIG. 11(B), the opening 251 and the opening As a result, the conductive films 243 and 255 in the respective openings are It is possible to increase the coverage of 53. As a result, the yield can be increased.

[0269] In FIG. 11B, the metal oxide film 209 The side surface of a faces the conductive film 243 which functions as a gate electrode. In the channel width direction of the transistor, the side surface of the metal oxide film 209a is It faces the conductive film 253, which has the same potential as the conductive films 203 and 243 that function as electrodes. Therefore, the electric field of the conductive film 203 and the conductive film 243 is not only on the plane of the metal oxide film 209a but also As a result, the region where carriers flow in the metal oxide film 209a is , the interface between the insulating film 207a and the metal oxide film 209a, and the interface between the metal oxide film 209a and the insulating film Since the area is wide and includes not only the interface with 211c but also the inside of the metal oxide film 209a, The amount of carrier movement in the transistor increases. As a result, the on-current of the transistor As the value of ion density increases, the field-effect mobility increases, typically reaching 10 cm 2 / V·s or more, even 20cm 2 / V·s or more. By making the diameter of the electrode between 0.5 μm and 6.5 μm, preferably between 1 μm and 6 μm, the electrode The increase in field effect mobility is significant.

[0270] In addition, at the end of the metal oxide film 209a processed by etching or the like, The damage caused by this leads to the formation of defects, and the wafer is contaminated by the adhesion of impurities. One of the conductive films 203 and 243 that function as a gate electrode in a transistor When only the metal oxide film 209a is formed, even if the metal oxide film 209a is intrinsic or substantially intrinsic, the electric field By applying such stress, the edge of the metal oxide film 209a is activated, and n In addition, the n-type region is likely to be a low-resistance region. If the n-type region is placed linearly between the n-type and n-type regions, the n-type region will become a carrier path, resulting in parasitic charges. As a result, the drain current rises gradually with the threshold voltage. , and the threshold voltage of the transistor is shifted negatively. As shown in FIGS. 11B and 11C, the conductive film 203 and the conductive film 24 are at the same potential. 3, and the conductive film 243 faces the side surface of the metal oxide film 209a in the channel width direction. By directing the electric field of the conductive film 243, the electric field of the conductive film 243 also affects the side surface of the metal oxide film 209a. As a result, the parasitic charge on the side surface of the metal oxide film 209a or the edge including the side surface and its vicinity As a result, the rise in drain current at the threshold voltage is not steep. This results in a transistor with excellent electrical properties.

[0271] In addition, the conductive films 203 and 243 each shield an electric field from the outside. In order to have a shielding function, a conductive film 243 is provided between the substrate 201 and the conductive film 243 and on the conductive film 243. As a result, the fixed charges generated by the metal oxide film 209a do not affect the metal oxide film 209a. Apply a negative potential to the gate electrode - Gate Bias-Temperature Transistor (GBT) The degradation of the drain voltage during the stress test is suppressed, and the on-state current at different drain voltages is also improved. Fluctuations in the rising voltage of the current can be suppressed.

[0272] The BT stress test is a type of accelerated test that detects the transitions that occur during long-term use. It is possible to evaluate the characteristic changes (i.e., aging) of a transistor in a short time. The amount of change in the threshold voltage of a transistor before and after stress testing is used to examine reliability. This is an important indicator. The smaller the amount of change in threshold voltage before and after the BT stress test, the better. Therefore, it can be said that this is a highly reliable transistor.

[0273] In addition, in FIG. 11(B) and FIG. 11(C), the metal oxide An opening is provided on one side surface of the film 109a, and the conductive film 203 and the conductive film 243 is electrically connected, but an opening is also provided on the other side, and a conductor is The conductive film 203 and the conductive film 243 may be electrically connected. The increase in the value can be prevented, and the conductive film 243 can be formed on both sides of the metal oxide film 209a. The electric field of the metal oxide film 209a can be influenced by the electric field of the metal oxide film 209a, and the on-current of the transistor can be increased. This can increase the field effect mobility as well as the carrier density.

[0274] Note that the structures and methods described in this embodiment may be different from the structures and methods described in other embodiments. They can be used in appropriate combination.

[0275] (Embodiment 5) A driver circuit can be formed using the transistors and capacitors described in any of Embodiments 1 to 4. It can be made.

[0276] The transistor 22d described in Embodiment 4 has a large on-state current and high mobility. Therefore, circuits that are made up of transistors that need to pass a large current, such as buffers, By using the transistor 22d, the channel length and the channel width can be reduced. This allows the area of ​​the transistor to be reduced. In a semiconductor device having a driving circuit in the peripheral portion, typically a display device, By reducing the area of ​​the operating circuit, the area of ​​the pixel portion in the display device can be increased. That is, it is possible to narrow the frame of the display device.

[0277] Note that the structures and methods described in this embodiment may be different from the structures and methods described in other embodiments. They can be used in appropriate combination.

[0278] (Sixth embodiment) In this embodiment, the semiconductor device described in the above embodiment is used as an example of a semiconductor device. The electronic devices that can be installed will be described.

[0279] Examples of electronic devices include television sets (also known as televisions or television receivers). (hereinafter referred to as "computer monitors"), digital cameras, digital video cameras, digital photo frames, mobile phones (also called mobile phones or mobile phone devices), portable game consoles, Examples include portable information terminals, audio playback devices, and large game machines such as pachinko machines. A specific example of such an electronic device is shown in FIG.

[0280] FIG. 12(A) shows an example of a television device. The television device 7100 is A display unit 7103 is incorporated in the housing 7101. The display unit 7103 displays an image. The display device described in the above embodiment modes can be used for the display portion 7103. In this example, the housing 7101 is supported by a stand 7105. It shows.

[0281] The television device 7100 can be operated using an operation switch provided on the housing 7101 or a separate remote control. This can be done by the remote controller 7110. The operation keys 7109 can be used to operate the channel and volume. The image displayed on the remote controller 7110 can be controlled. A display unit 7107 for displaying information output from the remote controller is provided. You may do so.

[0282] The television device 7100 includes a receiver, a modem, and the like. It is possible to receive general television broadcasts, and also to receive wired or wireless signals via a modem. By connecting to a communication network, it can be one-way (sender to receiver) or two-way It is also possible to communicate information in both directions (between a sender and a receiver, or between receivers). .

[0283] FIG. 12B shows a computer, which includes a main body 7201, a housing 7202, a display unit 7203, It includes a keyboard 7204, an external connection port 7205, a pointing device 7206, etc. Note that the computer uses the display device described in the above embodiment mode as the display portion 7203. It is possible.

[0284] FIG. 12C shows a portable gaming machine, which is composed of two housings, a housing 7301 and a housing 7302. The housing 7301 is connected to the connector 7303 so as to be openable and closable. A display portion 7305 is incorporated in the housing 7302. The portable gaming machine shown in FIG. 12(C) also includes a speaker unit 7306, a recording medium insertion unit 73 07, LED lamp 7308, input means (operation key 7309, connection terminal 7310, sensor 7311 (force, displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature , chemicals, voice, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, (including functions for measuring vibration, odor, or infrared rays), microphone 7312) Of course, the configuration of the portable gaming machine is not limited to the above. The display device described in the above embodiment mode may be used for both or either of the display portion 7304 and the display portion 7305. The equipment used may be the same as shown in Figure 1, and other auxiliary equipment may be provided as appropriate. The portable gaming machine shown in 2(C) reads the program or data recorded on the recording medium. It also has the function of displaying information on the display screen and communicating wirelessly with other portable gaming machines. The functions of the portable gaming machine shown in FIG. 12(C) are not limited to these. , can have a variety of functions.

[0285] FIG. 12D shows an example of a mobile phone. The mobile phone 7400 includes a housing 740 1, in addition to a display unit 7402, operation buttons 7403, an external connection port 7404, The mobile phone 7400 is equipped with a speaker 7405, a microphone 7406, and the like. The display device described in the above embodiment mode is used for the display portion 7402 .

[0286] In a mobile phone 7400 shown in FIG. 12D, when the display portion 7402 is touched with a finger or the like, You can input information, make calls, write emails, etc. This can be done by touching the display portion 7402 with a finger or the like.

[0287] The screen of the display unit 7402 has three main modes. The first is a mode that mainly displays images. The first mode is a display mode, and the second mode is an input mode that mainly inputs information such as characters. This is a display + input mode that combines the display mode and the input mode.

[0288] For example, when making a call or creating an email, the display portion 7402 is used for inputting characters. In this case, you can input characters displayed on the screen. In this case, a keyboard or number buttons can be displayed on most of the screen of the display unit 7402. preferable.

[0289] In addition, the mobile phone 7400 includes a sensor for detecting tilt, such as a gyro or an acceleration sensor. By providing a detection device having the above, the orientation of the mobile phone 7400 (portrait or landscape) can be determined, The screen display on the display portion 7402 can be automatically switched.

[0290] The screen mode can be switched by touching the display portion 7402 or the housing 7401. This is done by operating the operation button 7403. Also, the type of image displayed on the display unit 7402 can be changed. For example, the image signal to be displayed on the display unit may be switched depending on the type. If it is image data, the mode is switched to display mode, and if it is text data, the mode is switched to input mode.

[0291] In the input mode, a signal detected by the optical sensor of the display unit 7402 is detected and displayed. If there is no input by touch operation on the display unit 7402 for a certain period of time, the screen mode is changed to the input mode. Alternatively, the display mode may be switched from the normal mode to the display mode.

[0292] The display portion 7402 can also function as an image sensor. By touching 402 with the palm or fingers and capturing an image of the palm print, fingerprint, etc., personal authentication can be performed. In addition, a backlight that emits near-infrared light in the display unit or a sensing device that emits near-infrared light By using a light source, it is also possible to capture images of finger veins, palm veins, etc.

[0293] FIG. 12(E) shows an example of a folding computer. The computer 7450 is made up of a housing 7451L and a housing 7451R connected by a hinge 7454. In addition, the operation button 7453, the left speaker 7455L and the right speaker 7455L are provided. In addition to the 455R, the computer 7450 also has an external connection port 745 (not shown) on the side of the computer 7450. 6. The display unit 7452L is provided on the housing 7451L, and the display unit 7452R is provided on the housing 7451R. When the hinge 7454 is folded so that the display portions 7452R face each other, the display The part can be protected by a housing.

[0294] The display unit 7452L and the display unit 7452R not only display images but also display information when touched with a finger or the like. For example, you can touch and select an icon representing an installed program. You can also start a program by changing the distance between your fingers touching two points on the image. You can zoom in or out on the image by touching a point on the image or by moving your finger. You can also display an image of a keyboard and use your fingers to move the displayed letters and symbols. You can also select and enter information.

[0295] In addition, the computer 7450 is equipped with a gyro, an acceleration sensor, and a GPS (Global Positioning System). It is equipped with a GPS receiver, a fingerprint sensor, and a video camera. For example, a detection device having a sensor for detecting tilt such as a gyro or an acceleration sensor may be used. By setting up a position, the orientation of the computer 7450 (portrait or landscape) can be determined and the screen to be displayed can be adjusted. You can set it to automatically switch orientation.

[0296] The computer 7450 can also be connected to a network. In addition to being able to display information on the Internet, it can also remotely control other electronic devices connected to the network. It can be used as a terminal to operate from.

[0297] Note that the structures and methods described in this embodiment may be different from the structures and methods described in other embodiments. They can be used in appropriate combination.

Claims

1. a first metal oxide film having a channel formation region of a transistor; a scan line of the transistor; a source wiring electrically connected to the first metal oxide film; a pixel electrode electrically connected to the first metal oxide film; a second metal oxide film having a region overlapping the pixel electrode via an insulating film; a wiring electrically connected to the second metal oxide film; the wiring has a region that is arranged across a plurality of pixels that are arranged in a direction in which the source wiring extends, In a plan view, the pixel electrode does not overlap with the wiring, the wiring has a first region and a second region having a line width narrower than that of the first region, the source line has a third region and a fourth region having a line width narrower than that of the third region, The liquid crystal display device, wherein the scanning line overlaps the second region and the fourth region.

2. In claim 1, A liquid crystal display device comprising an oxide insulating film having a region in contact with an upper surface of the first metal oxide film.

Images