Indication device

Abstract

To provide a manufacturing method capable of reducing cost in a semiconductor device which has high opening ratio and has a capacitive element capable of increasing charge capacity; or provide a manufacturing method capable of reducing cost in the semiconductor device capable of reducing power consumption.SOLUTION: A mask formed by a process of using a multi-gradation photo mask is used to form a metal oxide film having a channel region, the metal oxide film functioning as a pixel electrode, and a source electrode and a drain electrode. An oxide insulation film is further formed on the metal oxide film having the channel region, and a nitride insulation film is formed on the oxide insulation film and the metal oxide film functioning as the pixel electrode; as a result, conductivity of the metal oxide film functioning as the pixel electrode can be improved.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an article, a method, or a manufacturing method. Alternatively, the present invention relates to a process, a machi ne, a manufacture, or a composition (composition of matter). In particula r, one embodiment of the present invention relates to a semiconductor device, a display device, a light-emitting device, a power storage device, a memory device, these or a driving method thereof, or a manufacturing method thereof. In particular, the present invention relates to, for example, a transis tor, and a method for manufacturing a semiconductor device including the same. Background Art

[0002] Many transistors used in flat panel displays typified by liquid crystal display devices and light-emitting display devices are formed of amorphous silicon or single crystal sil icon formed over a glass substrate, or a silicon semiconductor such as polycrystalline silicon. Further, the transis tors using such silicon semiconductors are also used in integrated circuits (ICs) and the like.

[0003] In recent years, instead of silicon semiconductors, a technique of using a metal oxide exhibiting semiconductor characteristics for a transistor has attracted attention. In this specification, a metal oxide exhibiting semiconductor characteristics is referred to as an oxide semiconductor.

[0004] For example, a technique in which a transistor is manufactured using zinc oxide or an In-Ga-Zn-based oxide as an oxide semiconductor and the transistor is used as a switching element or the like for a pixel of a display device is disclosed (see Patent Document 1). Prior Art Document Patent Document

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

[0006] Display devices available on the market tend to have larger screen sizes with diagonal dimensions of 40 inches or more , and development is also being conducted with screen sizes of 120 inches or more in consideration . For this reason, for glass substrates used in display devices, increasing the area to 8th generation or larger is progressing.

[0007] Along with the increase in area of glass substrates, in exposure apparatuses used in manufacturing processes of display devices, the photomask used becomes larger, and the price of the photomask has become a problem. For example, a 10th generation photomask is expensive, costing more than 100 million yen per sheet, so development of a manufacturing process that reduces the number of photomasks is demanded.

[0008] On the other hand, in a liquid crystal display device which is an example of a display device, increasing the charge capacitance of the capacitive element enables the orientation of the liquid crystal molecules of the liquid crystal element to be kept constant when an electric field is applied for a longer period of time. In a display device that displays still images, being able to extend this period makes it possible to reduce the number of times image data is rewritten, which can be expected to reduce power consumption.

[0009] Therefore, in order to increase the charge capacitance of the capacitive element, there is a method of increasing the area occupied by the capacitive element , specifically, increasing the overlapping area of the pair of electrodes. However , in the above-described display device, in order to increase the overlapping area of the pair of electrodes, the light-shielding property is Increasing the area of ​​the conductive film reduces the aperture ratio of the pixels, which degrades the display quality of the image. .

[0010] Therefore, one aspect of the present invention is a container that has a high aperture ratio and can increase its charge capacity. This invention provides a manufacturing method that can reduce costs for semiconductor devices having quantitative elements. One of the challenges is to reduce power consumption. Alternatively, one aspect of the present invention relates to a semiconductor device capable of reducing power consumption. One of the objectives is to provide a manufacturing method that can reduce costs in this context. Alternatively, one aspect of the present invention aims to provide a novel semiconductor device. One aspect of the present invention aims to provide a novel display device. The description of the problem does not preclude the existence of other problems. Furthermore, one aspect of the present invention is not necessarily... However, it is not necessary to solve all of these problems. Other issues are addressed in the specification and figures. This will become clear from the descriptions of the surfaces, claims, etc., and will be evident from the specifications, drawings, claims, etc. From the description, it is possible to extract other issues besides those mentioned above. [Means for solving the problem]

[0011] One aspect of the present invention uses a mask formed by a process using a multi-gradation photomask. a metal oxide film having a channel region, a metal oxide film that functions as a pixel electrode, and The invention is characterized by forming a drain electrode and a drain electrode. Thus, a mask of the first shape having a first thickness and a second thickness that is thicker than the first thickness is formed. This is done. Using the mask of the first shape, the metal oxide film and conductive film on the substrate are etched. The metal oxide film having a channel region and the metal oxide film functioning as a pixel electrode. Next, the mask of the first shape is processed to remove the mask of the region of the first thickness. Next, the second thickness region is left intact to form the mask of the second shape. Using this method, the conductive film formed on the metal oxide film is etched, and the source electrode and drain An electrode is formed. In addition, a capacitance line may be formed in this step. Furthermore, a channel An oxide insulating film is formed on a metal oxide film having a region, and the oxide insulating film and the pixel electrode are formed By forming a nitride insulating film on a metal oxide film that functions as a pixel electrode, It is possible to improve the conductivity of metal oxide films.

[0012] One aspect of the present invention involves forming a gate electrode and a gate insulating film on an insulating surface, and the gate insulating film A first metal oxide film and a first conductive film are formed on top of the first conductive film, and a first thickness is formed on the first conductive film. A first mask having a region and a region having a second thickness greater than the first thickness, A second mask having the same thickness as the first mask is formed, and the first mask and the second mask are formed Using this method, the first conductive film and the first metal oxide film are etched, respectively, to form the second conductive film. Next, a third conductive film, and a second and third metal oxide films are formed. After processing the first mask to form the third mask and removing the second mask Then, using a third mask, the second conductive film is etched, and a saw is applied to the second metal oxide film. A fourth conductive film and a fifth conductive film are formed that function as a drain electrode and a drain electrode, respectively. Next, remove the third conductive film. Then, apply the second metal oxide film, the fourth conductive film, and the fifth conductive film. A first insulating film is formed on the film, and a second insulating film is formed on the first insulating film and the third metal oxide film. After forming the first insulating film and a portion of the second insulating film are etched, and the first insulating film and Next, an opening is formed in the second insulating film. Then, it functions as a pixel electrode in contact with the fifth conductive film. A sixth conductive film, and a seventh conductive film in contact with the third metal oxide film, which functions as a capacitance line. This is a method for fabricating semiconductor devices that form a film.

[0013] Furthermore, the first insulating film has an opening on the third metal oxide film.

[0014] Furthermore, the second metal oxide film and the third metal oxide film have different hydrogen concentrations. The third metal oxide film has a higher hydrogen concentration than the second metal oxide film.

[0015] Furthermore, the third metal oxide film is conductive, and the third metal oxide film, the second insulating film, and A capacitive element is constructed using a conductive film that is also transparent to light.

[0016] Furthermore, the first metal oxide film, the second metal oxide film, and the third metal oxide film are light-transmitting. It has. Furthermore, the first metal oxide film, the second metal oxide film, and the third metal oxide film are It has at least one of In, Ga, and Zn. Also, a first metal oxide film, a second gold It is preferable that the third metal oxide film and the third metal oxide film are composed of the same metal element. .

[0017] Furthermore, the first insulating film is formed using an oxide insulating film. Note that the first insulating film is heated It is preferable that the oxide insulating film contains an oxide insulating film from which some of the oxygen is desorbed. Furthermore, the second insulating film is , formed using a nitride insulating film. [Effects of the Invention]

[0018] According to one aspect of the present invention, a capacitance element capable of having a high aperture ratio and increasing charge capacitance is provided. In a method for manufacturing a semiconductor device having children, costs can be reduced. Power consumption In a method for manufacturing semiconductor devices that can reduce costs, the cost can be reduced. According to one aspect of the present invention, a novel semiconductor device can be provided. Or, the present invention A novel display device can be provided by one embodiment. Note that the effects of these are described below. This does not preclude the existence of other effects. Furthermore, one aspect of the present invention does not necessarily preclude the existence of these effects. It is not necessary to have all of these effects. Furthermore, any effects other than those mentioned above will be described in the specification, drawings, claims, etc. This will become clear from the description, and from the description in the specification, drawings, claims, etc. It is possible to extract effects other than those mentioned above. [Brief explanation of the drawing]

[0019] [Figure 1] These are block diagrams and circuit diagrams illustrating one form of a semiconductor device. [Figure 2] This is a top view illustrating one form of a pixel. [Figure 3] This is a cross-sectional view illustrating one form of a method for manufacturing a device substrate. [Figure 4] This is a cross-sectional view illustrating one form of a method for manufacturing a device substrate. [Figure 5] This is a cross-sectional view illustrating one form of a method for manufacturing a device substrate. [Figure 6] This is a top view illustrating one form of a pixel. [Figure 7] This is a cross-sectional view illustrating one form of a method for manufacturing a device substrate. [Figure 8] This is a top view illustrating one form of a pixel. [Figure 9] This is a cross-sectional view illustrating one form of a method for manufacturing a device substrate. [Figure 10] This is a cross-sectional view illustrating one form of a method for manufacturing a device substrate. [Figure 11] This is a cross-sectional view illustrating one form of transistor. [Figure 12] This is a diagram illustrating electronic devices. [Figure 13] This is a cross-sectional view illustrating one form of a device substrate. [Figure 14] This is a top view illustrating one form of a pixel. [Figure 15] This is a cross-sectional view illustrating one form of transistor. [Figure 16] This is a diagram illustrating the display module. [Figure 17] This diagram illustrates the temperature dependence of resistivity. [Figure 18] These are a top view and a cross-sectional view illustrating the structure of the sample. [Figure 19] This diagram illustrates the resistance values ​​of metal oxide films. [Modes for carrying out the invention]

[0020] The embodiments of the present invention will be described in detail below with reference to the drawings. However, the present invention The present invention is not limited to the following description, and its form and scope may not depart from the spirit and scope of the present invention. Those skilled in the art will readily understand that the details can be modified in various ways. Therefore, the present invention The following embodiments and examples are not to be interpreted as being limited to their descriptions. In the embodiments and examples described below, parts that are the same or have similar functions In some cases, the same reference numeral or hatch pattern is used in common across different drawings, and the repetition of this pattern is used. I will omit the explanation of the repetition.

[0021] In each figure described herein, the size, film thickness, or region of each component is as follows: It may be exaggerated for clarity. Therefore, it is not necessarily limited to that scale. stomach.

[0022] Furthermore, the terms "first," "second," "third," etc. used in this specification are used to avoid confusion of constituent elements. This is a selection and not a numerical limit. Therefore, for example, "the first" This can be explained by substituting "the second" or "the third" as appropriate.

[0023] Furthermore, the functions of "source" and "drain" are used in situations where the direction of current changes during circuit operation. In this specification, "sauce" and "dressing" may be used interchangeably. The term "in" may be used interchangeably.

[0024] Furthermore, voltage refers to the potential difference between two points, while electric potential refers to the electrostatic field at a given point. This refers to the electrostatic energy (electrical potential energy) possessed by a unit charge within a given object. Furthermore, generally speaking, the potential difference between the potential at a certain point and a reference potential (for example, the ground potential) This is simply called electric potential or voltage, and the terms electric potential and voltage are often used as synonyms. Therefore, unless otherwise specified in this specification, potential may be read as voltage. You may substitute "voltage" with "potential."

[0025] In this specification, when an etching process is performed after a photolithography process: The mask formed during the photolithography process shall be removed.

[0026] (Embodiment 1) In this embodiment, a capacitive element is provided that has a high aperture ratio and can increase the charge capacitance. The objective is to provide a manufacturing method for semiconductor devices that can reduce costs. This is one aspect of the present invention. Alternatively, one aspect of the present invention relates to a semiconductor device capable of reducing power consumption. Therefore, one of the objectives is to provide a manufacturing method that can reduce costs.

[0027] Furthermore, in the case of metal oxides, an oxide semiconductor, which is a metal oxide having semiconductor properties, is used. In transistors, one example of a defect that leads to poor electrical characteristics of the transistor is oxygen There is a defect. For example, a transient using an oxide semiconductor film that contains oxygen vacancies in the film. The threshold voltage tends to fluctuate in the negative direction, making it prone to normally-on characteristics. This is because oxygen vacancies in the oxide semiconductor film generate electric charge, resulting in lower resistance. Yes. If a transistor has normally-on characteristics, malfunctions are more likely to occur during operation. Various problems can arise, such as increased power consumption when not in operation. Through chemical testing and stress testing, the electrical characteristics of a transistor, particularly the variation in threshold voltage, can be determined. There is a problem with it increasing.

[0028] Furthermore, impurities such as silicon and carbon, which are constituent elements of insulating films, are not limited to oxygen vacancies. This causes poor electrical properties in the transistor. Therefore, the impurity is mixed into the oxide semiconductor film. As a result, the oxide semiconductor film becomes less resistive, which affects its performance over time and in stress tests. This leads to a problem where the electrical characteristics of the transistor, particularly the fluctuation in the threshold voltage, increase. There is.

[0029] Therefore, in this embodiment, in addition to the problems that the invention aims to solve, the oxide semiconductor film is also In a semiconductor device equipped with a transistor, the channel region of the oxide semiconductor film One of the challenges is to reduce oxygen deficiencies and impurity concentrations in oxide semiconductor films.

[0030] In this embodiment, as a method to solve one of the above problems, the method for manufacturing a semiconductor device is described below. The following will be explained with reference to the drawings. In this embodiment, a process using a multi-gradation photomask is performed , forming a metal oxide film having a channel region, and a source electrode and a drain electrode. It is characterized by the following.

[0031] Figure 1(A) shows an example of a semiconductor device. The semiconductor device shown in Figure 1(A) has a pixel section 11 The scan line drive circuit 14 and the signal line drive circuit 16 are arranged in parallel or approximately parallel to each other. Furthermore, m scan lines 17 whose potential is controlled by the scan line driving circuit 14, and each of them parallel to each other. or n signal lines arranged approximately parallel to each other, and whose potential is controlled by the signal line drive circuit 16. It has 19 and, furthermore, the pixel section 11 has a plurality of pixels 13 arranged in a matrix. In addition, there are capacity lines 15 arranged parallel or nearly parallel to each other along the signal line 19. The capacitance lines 15 are arranged parallel or nearly parallel to each other along the scan lines 17. It may be included. Also, the scan line drive circuit 14 and the signal line drive circuit 16 may be grouped together as the drive circuit section. There are cases where this is true.

[0032] Each scan line 17 is 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 the row. Of the pixels 13 arranged in a row, m pixels 13 in any row are electrically connected The process continues. m and n are both integers greater than or equal to 1. Also, each capacitance line 15 is arranged in m rows and n columns. Of the installed pixels 13, n pixels 13 arranged in any row are electrically connected. Furthermore, the capacity lines 15 are arranged parallel or nearly parallel to the signal lines 19. In this case, m pixels are located in any of the columns of the m rows and n columns of the pixel 13. It is electrically connected to 13.

[0033] Figures 1(B) and 1(C) show the number of times that can be used for the pixel 13 of the display device shown in Figure 1(A). An example of a road configuration is shown.

[0034] The pixel 13 shown in Figure 1(B) consists of a liquid crystal element 21, a transistor 22, and a capacitive element 25. , has.

[0035] 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 orientation state of the liquid crystal element 21 is set according to the data being written to it. Also, multiple pixels 1 A common potential (common potential) is applied to one of the pair of electrodes of the liquid crystal element 21 that each of the 3 possesses. It is also possible to set a different potential on one of the pair of electrodes of the liquid crystal element 21 for each pixel 13 in each row. You may give it.

[0036] Furthermore, the liquid crystal element 21 controls the transmission or non-transmission of light by the optical modulation effect of the liquid crystal. It is an element that... Note that the optical modulation effect of liquid crystals is due to the electric field applied to the liquid crystal (horizontal electric field, vertical electric field). It is controlled by an electric field in the direction or an electric field in the oblique direction. Note that the liquid crystal element 21 is Nematic liquid crystal, cholesteric liquid crystal, smectic liquid crystal, thermotropic liquid crystal, Examples include iotropic liquid crystals, ferroelectric liquid crystals, and antiferroelectric liquid crystals.

[0037] The driving method for the display device having the liquid crystal element 21 is, for example, TN mode, VA mode. , 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 may also use modes such as Verse Bend Alignment. However, It is not limited to this, and various liquid crystal elements and their driving methods can be used.

[0038] Furthermore, a liquid crystal composition containing a liquid crystal exhibiting a blue phase and a chiral agent. The liquid crystal element may be constructed in this manner. The liquid crystal exhibiting the blue phase has a response speed of 1 msec or less. Because it is short and optically isotropic, orientation processing is unnecessary, and it has low dependence on the viewing angle.

[0039] In the configuration of the pixel 13 shown in Figure 1(B), the source electrode and the drain electrode of the transistor 22 One electrode is electrically connected to the signal line 19, and the other is connected to the other electrode of the liquid crystal element 21. It is electrically connected to the scan line 17. It is connected to the transistor 22, which is either on or off, and the data It has a function to control the writing of signal data. Note that transistor 22 is in its actual form. A transistor as shown in any of Embodiments 1 to 7 can be used.

[0040] In the configuration of the pixel 13 shown in Figure 1(B), one of the pair of electrodes of the capacitive element 25 is at a potential One is electrically connected to the capacitance line 15 that supplies power, and the other is connected to the other of the pair of electrodes of the liquid crystal element 21. It is electrically connected to the capacitor. The potential value of the capacitance line 15 is set appropriately according to the specifications of the pixel 13. The capacitive element 25 has the function of a holding capacitor that holds the written data. ru.

[0041] For example, in the display device having pixels 13 as shown in Figure 1(B), each row is driven by the scan line driving circuit 14. The pixels 13 are selected sequentially, and the transistor 22 is turned on to write the data signal. It gets crowded.

[0042] The pixel 13 on which data has been written is held in a state when transistor 22 is turned off. This is how it works. By doing this row by row, the image can be displayed.

[0043] Furthermore, the pixel 13 shown in Figure 1(C) is a transistor 33 that performs switching of the display element. And, a transistor 22 that controls the driving of the pixels, a transistor 35, a capacitive element 25, It has a light-emitting element 31.

[0044] An example of a light-emitting element 31 is an anode, a cathode, and an EL layer sandwiched between the anode and the cathode. Examples of elements include those having EL. An example of an EL layer is that the light emitted (fluorescence) from singlet excitons is A layer having a material capable of emission (phosphorescence) from triplet excitons, a single layer Materials capable of luminescence (fluorescence) from no-t excitons and materials capable of luminescence (phosphorescence) from triplet excitons There are layers containing material, etc.

[0045] One of the source and drain electrodes of transistor 33 is a signal to which a data signal is applied. It is electrically connected to line 19. Furthermore, the gate electrode of transistor 33 is connected to the gate signal It is electrically connected to the given scan line 17.

[0046] Transistor 33 is either on or off, which controls the data of the data signal. It has a function to control writing.

[0047] One of the source and drain electrodes of transistor 22 functions as the anode. The wiring 37 is electrically connected, and the source electrode and the other drain electrode of transistor 22 are It is electrically connected to one electrode of the light-emitting element 31. Furthermore, the gate of transistor 22 The electrodes are the source electrode and the other drain electrode of the transistor 33, and one of the capacitive elements 25. It is electrically connected to one of the electrodes.

[0048] Transistor 22, when in an ON or OFF state, causes current to flow to the light-emitting element 31. It has a function to control the current.

[0049] The source electrode and one of the drain electrodes of transistor 35 are given a data reference potential. The wiring 39 is connected, and the source electrode and the other drain electrode of the transistor 35 emit light. It is electrically connected to one electrode of element 31 and to the other electrode of capacitive element 25. Furthermore, The gate electrode of transistor 35 is electrically connected to the scan line 17 to which the gate signal is applied. It can be done.

[0050] The transistor 35 has the function of adjusting the current flowing to the light-emitting element 31. For example, If 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 and drain electrodes is connected is monitored. This allows the current flowing through the light-emitting element 31 to be corrected. The potential can be set to, for example, 0V.

[0051] One of the pair of electrodes of the capacitive element 25 is connected to the source electrode and drain electrode of the transistor 33. On the other hand, and electrically connected to the gate electrode of transistor 22, a pair of capacitive elements 25 The other electrode is the source electrode and the other drain electrode of transistor 35, and the light-emitting element 3 It is electrically connected to one of the electrodes of 1.

[0052] In the pixel 13 configuration shown in Figure 1(C), the capacitive element 25 retains the written data. It has the function of holding capacity.

[0053] One of the pair of electrodes of the light-emitting element 31 is the source electrode and drain electrode of the transistor 35. On the other hand, the other side of the capacitive element 25, and the source electrode and drain electrode of the transistor 22 It is electrically connected to the other side. Also, the other of the pair of electrodes of the light-emitting element 31 is used as a cathode. It is electrically connected to the functioning wiring 41.

[0054] As the light-emitting element 31, for example, an organic electroluminescent element (also known as an organic EL element) (u) etc. can be used. However, the light-emitting element 31 is not limited to this, Inorganic EL elements made of mechanical materials may also be used.

[0055] Furthermore, a high power supply potential VDD is supplied to one of the wirings 37 and 41, while a low power supply potential VDD is supplied to the other. A power supply potential VSS is applied. In the configuration shown in Figure 1(C), the high power supply potential is applied to wiring 37. The configuration provides VDD to the wiring 41 and a low power supply potential VSS to the wiring 41.

[0056] In the display device having pixels 13 in Figure 1(C), the scanning line driving circuit 14 drives each row of pixels 1 Select 3 sequentially, turn on transistor 22, and write the data signal.

[0057] The pixel 13 on which data has been written is held in a state when transistor 22 is turned off. Furthermore, because transistor 22 is connected to capacitive element 25, the written data This makes it possible to retain data for a long time. Also, the transistor 33 allows the source electrode to The amount of current flowing between the and the drain electrode is controlled, and the light-emitting element 31 responds to the amount of current flowing. It emits light based on its brightness. By doing this sequentially for each row, an image can be displayed.

[0058] In this specification, etc., display element, display device having a display element, light-emitting element Light-emitting devices, which are devices having sub-elements and light-emitting elements, can take various forms or various It may have such elements. Examples include display elements, display devices, light-emitting elements, or light-emitting devices. Therefore, EL (electroluminescent) elements (EL elements including organic and inorganic materials, organic EL elements (inorganic EL elements), transistors (transistors that emit light in response to current), electron Emission elements, liquid crystal elements, electronic inks, electrophoretic elements, digital micromirror devices (D MD), DMS (Digital Micro Shutter), etc., are produced by electromagnetic interaction. Some display media have properties such as transparency, brightness, reflectance, and transmittance that change. An example of a display device using electrons is an EL display. Examples of such display devices include field emission displays (FEDs) or SEs. D-type flat-panel display (SED: Surface-conduction Electric) Examples include tron-emitter displays. One example is a liquid crystal display (transmissive liquid crystal display, semi-transmissive liquid crystal display). (Reflective liquid crystal displays, direct-view liquid crystal displays, projection liquid crystal displays, etc.) Yes, there are. Examples of display devices using electronic ink or electrophoretic elements include electronic paper. There is.

[0059] Next, we will explain a specific example of a component substrate for a liquid crystal display device that uses liquid crystal elements in pixel 13. To clarify, Figure 2 shows a top view of pixel 13, as shown in Figure 1(B).

[0060] In Figure 2, the conductive film 103, which functions as a scan line, is oriented in a direction approximately perpendicular to the signal line (in the figure). It is provided extending in the left-right direction. The conductive film 114, which functions as a signal line, is located on the scan line. They are provided extending in a nearly perpendicular direction (up and down in the diagram). They function as conductive capacitance lines. The film 116 is provided extending in a direction parallel to the signal line. The conductive film 116 is a pixel They are separated for each. Therefore, the conductive film 124 is connected to the conductive film 116 of the adjacent pixel. As a result, the conductive films 116 of adjacent pixels are electrically connected. The functional conductive film 103 is electrically connected to the scan line drive circuit 14 (see Figure 1(A)). It is composed of a conductive film 114 that functions as a signal line and a conductive film 116 that functions as a capacitance line. The conductive film 124 is electrically connected to the signal line drive circuit 16 (see Figure 1(A)). ru.

[0061] Transistor 22 is located in the region where the scan line and signal line intersect. T22 is a conductive film 103 that functions as a gate electrode, a gate insulating film (not shown in Figure 2). , a metal oxide film 109a in which a channel region is formed on the gate insulating film, source It is composed of conductive films 114 and 115 that function as electrodes and drain electrodes. The film 103 also functions as a scanning line, and the region that overlaps with the metal oxide film 109a is transient. It functions as the gate electrode of sta 22. The conductive film 114 also functions as a signal line. The region superimposed on the metal oxide film 109a is the source electrode or drain electrode of the transistor 22. It functions as a pole.

[0062] In this embodiment, in the planar shape, metal is attached to the outside of the edges of the conductive films 114 and 115. It is characterized by having the edge of the oxide film 109a located there. It also functions as a conductive line. The end of the metal oxide film 109c is located outside the end of the film 116.

[0063] Since the metal oxide film 109a is formed using a metal oxide that has semiconductor properties, In the metal oxide film 109a between conductive film 114 and conductive film 115, the channel region is shaped It will be accomplished.

[0064] Furthermore, the conductive film 115 has electrical properties with the light-transmitting conductive film 123 which functions as a pixel electrode. Connected.

[0065] The metal oxide film 109c is a film formed simultaneously with the metal oxide film 109a, and This is a film in which oxygen deficiencies are formed due to rasmal damage, etc., and its conductivity is enhanced. Alternatively, gold The genus oxide film 109c is a film formed simultaneously with the metal oxide film 109a, and is free of impurities. The film has enhanced conductivity due to the inclusion of [a certain substance]. Alternatively, the metal oxide film 109c is a metal This film is formed simultaneously with the oxide film 109a and contains impurities, and also causes plasma damage. This is a film in which oxygen deficiencies are formed through processes such as aging, thereby increasing its conductivity.

[0066] The capacitive element 25 consists of a metal oxide film 109c formed on the gate insulating film and a pixel electrode. A conductive film 123 having light-transmitting properties that functions in conjunction with a nitride insulating film provided on the transistor 22. It is composed of a dielectric film formed in a film. The metal oxide film 109c is light-transmitting. Therefore, the capacitive element 25 is light-transmitting. Also, the capacitive element 25 functions as one of a pair of electrodes. The metal oxide film 109c is connected to the conductive film 116, which functions as a capacitance line.

[0067] Thus, since the capacitive element 25 is light-transmitting, the capacitive element 25 can be made larger within the pixel 13. It can be formed over a large area. Therefore, while increasing the opening ratio, it is preferably 50% or more. It is possible to set it to 55% or more, preferably 60% or more, and to increase the charge capacity. A semiconductor device can be obtained. For example, a semiconductor device with high resolution, such as a liquid crystal display device. In this configuration, the pixel area becomes smaller, and the area of ​​the capacitive element also becomes smaller. Therefore, resolution In semiconductor devices with high capacitance, the charge capacitance accumulated in capacitive elements decreases. However, Furthermore, since the capacitive element 25 shown in this embodiment is light-transmitting, the capacitive element is provided in the pixel. This allows for obtaining sufficient charge capacitance in each pixel while increasing the aperture ratio. Specifically, pixel densities of 200 ppi or more, even 300 ppi or more, and even 500 ppi or more. It can be suitably used in high-resolution semiconductor devices with a resolution of i or higher.

[0068] Furthermore, the pixel 13 shown in Figure 2 is compared to the side parallel to the conductive film 103 which functions as a scan line. Therefore, the side parallel to the conductive film 114 that functions as a signal line is shorter, and the capacitance line and The conductive film 116 that functions in this way, and the conductive film 116 formed on adjacent pixels are electrically connected. The conductive film 124 is provided extending in a direction parallel to the conductive film 114 which functions as a signal line. This allows for a reduction in the area of ​​conductive films 114 and 116 within the pixel 13. Because it is capable, the aperture ratio can be increased.

[0069] Furthermore, one aspect of the present invention allows for an increase in the aperture ratio even in high-resolution display devices. Therefore, it is possible to efficiently utilize the light from light sources such as backlights, and the power consumption of the display device is reduced. The force can be reduced.

[0070] Next, using the cross-sectional view of the dashed line AB and the cross-sectional view of the dashed line CD shown in Figure 2, the display system The method for fabricating the element substrate will be explained below.

[0071] As shown in Figure 3(A), a conductive film 102 is formed on the substrate 101. Next, the first film A mask 131 is formed on the conductive film 102 by a photolithography process using a mask. do.

[0072] There are no major restrictions on the material of the substrate 101, but it should at least be able to withstand subsequent heat treatment. It must have heat resistance. For example, glass substrates, ceramic substrates, quartz substrates, etc. A fire substrate or the like may be used as substrate 101. Alternatively, silicon or silicon carbide may be used. Single-crystal semiconductor substrates, polycrystalline semiconductor substrates, silicon germanium, etc., formed using these materials. It is also possible to apply composite semiconductor substrates, SOI substrates, etc., and semiconductor elements on these substrates A substrate with a child attached may be used as the substrate 101. When using a substrate, the 6th generation (1500mm x 1850mm) and the 7th generation (1870mm) are available. m x 2200mm), 8th generation (2200mm x 2400mm), 9th generation (2400m Using large-area substrates such as m × 2800 mm, 10th generation (2950 mm × 3400 mm), etc. This makes it possible to manufacture large-scale display devices.

[0073] Furthermore, 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 stripped layer may be placed on the release layer. After fabricating the element portion having the inverter, the element portion is peeled off from the substrate 101 in the peeling layer. The element may be transferred to another substrate. As a result, the element can be mounted on substrates with low heat resistance or flexible substrates. A department can be established.

[0074] The conductive film 102 later becomes the conductive film 103 which functions as the gate electrode. The conductive film 102 is made of a conductive material that can be used as a gate electrode. 2. Choose from aluminum, chromium, copper, tantalum, titanium, molybdenum, and tungsten. The identified metal element, or an alloy containing the aforementioned metal element, or a combination of the aforementioned metal elements It can be formed using a combination of alloys, etc. Also, either manganese or zirconium Alternatively, one or more metal elements may be selected. Furthermore, the conductive film 102 may have a single-layer structure. It can be a single layer or a laminated structure of two or more layers. For example, a single layer of an aluminum film containing silicon. Layered structure, two-layer structure with an aluminum film stacked on top of a titanium film, titanium film on top of a titanium nitride film Stacked two-layer structure, two-layer structure with a tungsten film stacked on top of a titanium nitride film, tantalum nitride A two-layer structure consisting of a film or a tungsten film laminated on a tungsten nitride film, and a copper film on a titanium film. A two-layer structure consisting of a titanium film and an aluminum film laminated on top of the titanium film, and further... There are also three-layer structures, such as one in which a titanium film is formed on top of an aluminum layer. , one of the elements selected from tungsten, molybdenum, chromium, neodymium, and scandium Alternatively, an alloy film or nitride film made up of multiple layers may be used.

[0075] Furthermore, the conductive film 102 is an indium tin oxide film, an indium acid containing tungsten oxide. Indium 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 from a light-transmitting conductive material such as an indium tin oxide film with added ions is suitable. It can also be used. Furthermore, a film formed from the above-mentioned light-transmitting conductive material and the above-mentioned metal It can also be a layered structure of films formed from elements.

[0076] Here, a tungsten film with a thickness of 100 nm is used as the conductive film 102 by sputtering. It is formed by [method]. Next, a mask is formed by a photolithography process.

[0077] Next, a portion of the conductive film 102 is etched using the mask 131 to form a gate electrode. A functional conductive film 103 is formed by dry etching or / or wet etching. The conductive film 102 can be etched using this method. After this, the mask 131 is removed. Remove (see Figure 3(B)).

[0078] Here, a mask is used to dry-etch the tungsten film formed as conductive film 102. By chipping, a conductive film 103 that functions as a gate electrode is formed.

[0079] Next, as shown in Figure 3(C), insulating film 105, insulating film 106, metal oxide film 108, The conductive film 110 is formed sequentially. Next, a photolithography process using a second photomask is performed. Depending on the circumstances, masks 133 and 134 are formed on the conductive film 110. Here, the second photo This method is characterized by the use of a multi-tone mask as the mask.

[0080] A multi-gradation photomask is a mask that allows exposure at multiple levels of light intensity, and is a representative example. In general, there are gray tone masks, halftone masks, etc. Gray tone masks are transparent A light-shielding portion and a diffraction grating are formed on a light-sensitive substrate. The diffraction grating consists of slits and dots. The spacing between light-transmitting regions such as meshes is less than or equal to the resolution limit of the light used for exposure. This configuration controls the light transmittance. The halftone mask is placed on a light-transmitting substrate. A light-shielding portion and a semi-transparent portion are formed. The semi-transparent portion controls the transmittance of the light used for exposure. .

[0081] By using a multi-tone mask, the light intensity can be divided into three stages: exposed, partially exposed, and unexposed. Exposure can be performed in a single exposure by using a multi-gradation photomask. The development process then forms a resist mask with multiple (typically two) thicknesses. This makes it possible to reduce the number of photomasks. Here, metal acids In the process of forming the oxide film and conductive films 114, 115, and 116, a multi-gradation photomask is used. This allows us to reduce the number of photomasks by one.

[0082] Insulating film 105 and insulating film 106 will later become gate insulating films. Also, insulating film 105 This is because the conductive film 103, which functions as the substrate 101 and gate electrode, does not penetrate the metal oxide film 108. To prevent the diffusion of pure substances, it is preferable to form the film using a nitride insulating film. The edge film 106 is in contact with the metal oxide film 108. To reduce surface energy levels, it is preferable to form the insulating film 106 using an oxide insulating film.

[0083] Insulating film 105 is silicon nitride, silicon oxide nitride, aluminum nitride, aluminum oxide nitride. It can be formed using materials such as aluminum, and can be constructed in layers or as a single layer.

[0084] Insulating film 106 consists of silicon oxide, silicon oxide nitride, aluminum oxide, and hafniac oxide. It can be formed using materials such as gallium oxide or Ga-Zn-based metal oxides, and laminated or It will be installed as a single layer.

[0085] Furthermore, as the insulating film 106, hafnium silicate (HfSiO x ), nitrogen is added Hafnium silicate (HfSi x O y N z ), Nitrogen-added hafnium aluminum (HfAl x O y N z ), high-k materials such as hafnium oxide and yttrium oxide By using this material during formation, gate leakage in transistors can be reduced.

[0086] The total thickness of insulating film 105 and insulating film 106 is preferably 5 nm or more and 400 nm or less. Or, 10 nm to 300 nm, more preferably 50 nm to 250 nm. That's good.

[0087] Insulating film 105 and insulating film 106 are coated using methods such as CVD, sputtering, vapor deposition, and coating. It can be used as appropriate.

[0088] By providing the insulating film 105, which is formed of a nitride insulating film, as part of the gate insulating film, Impurities from the conductive film 103, which functions as a electrode, typically include hydrogen, nitrogen, and alkali. This prevents metals, or alkaline earth metals, etc., from migrating to the metal oxide film 109a. can.

[0089] Furthermore, as a gate insulating film, an insulating film formed with an oxide insulating film on the metal oxide film 109a side is used. By providing the film 106, the defect levels at the interface between the gate insulating film and the metal oxide film 109a This makes it possible to reduce the degradation of electrical characteristics. As a result, it is possible to obtain transistors with less degradation of electrical characteristics. It is possible.

[0090] Typical examples of metal oxide films 108 include In-Ga oxide films, In-Zn oxide films, and In -M-Zn oxide film (where M is Al, Ga, Ti, Y, Zr, La, Ce, or Nd), etc. There is a metal oxide film. Furthermore, since this metal oxide film has semiconductor properties, it is an oxide semiconductor. That is also possible.

[0091] Furthermore, when the metal oxide film 108 is an In-M-Zn oxide film, the sum of In and M is When set to 100 atomic%, the atomic ratio of In to M is preferably the ratio of In to M The preferred ratio of offspring is that In is greater than 25 atomic%, and M is less than 75 atomic%. In is greater than 34 atomic%, and M is less than 66 atomic%. To be satisfied.

[0092] The energy gap of the metal oxide film 108 is 2 eV or more, preferably 2.5 eV or more. More preferably, it is 3 eV or more. Thus, metal oxides with a wide energy gap. By using this method, the off-current of the transistor formed later can be reduced. .

[0093] As the metal oxide film 108, a metal oxide film with low carrier density is used. For example, gold 属 oxide film 108 has a carrier density of 1×10 17 carriers / cm 3 or less, preferably 1×10 15 carriers / cm 3 or less, more preferably 1×10 13 carriers / cm 3 or less, even more preferably 1 ×10 11 carriers / cm 3 or less metal oxide film is used.

[0094] 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, more preferably 3 nm or more and 50 nm or less.

[0095] The metal oxide film 108 can be formed by a sputtering method, a coating method, a pulsed laser deposition method, a laser ablation method, or the like.

[0096] In the case of forming the metal oxide film 108 by a sputtering method, for generating plasma an RF power supply device, an AC power supply device, a DC power supply device, or the like can be appropriately used as the power supply device.

[0097] As the sputtering gas, a rare gas (typically argon) atmosphere, an oxygen atmosphere, a mixture of a rare gas and oxygen is appropriately used. Note that in the case of a mixed gas of a rare gas and oxygen, it is preferable to increase the gas ratio of oxygen to the rare gas.

[0098] When the metal oxide film 108 is an In-M-Zn oxide film (M is Al, Ti, Ga, Y, Zr, La, Ce, Nd, or Hf), the atomic ratio of metal elements of the sputtering target used for forming the In-M-Zn oxide film satisfies the atomic ratio of metal elements In:M:Z Let n = x1:y1:z1. 、 x1 / y1 is between 1 / 3 and 6, and furthermore, between 1 and 6. The following conditions must be met, and z1 / y1 is preferably between 1 / 3 and 6, and more preferably between 1 and 6. Furthermore, by setting z1 / y1 to between 1 and 6, the metal oxide film 108 will be described later. CAAC-OS(C Axis Aligned Crystalline Oxid The film (e) becomes easier to form. Typical examples of the ratio of offspring include In:M:Zn=1:1:1 and In:M:Zn=3:1:2. Examples include In:M:Zn=5:5:6. Note that this is the atomic ratio of the metal oxide film 108 to be formed. Each of these represents a positive or negative error in the atomic ratio of the metal elements contained in the target mentioned above. Includes a 40% fluctuation.

[0099] To obtain a high-purity metal oxide film 108, only the chamber needs to be evacuated to a high vacuum. Furthermore, it is necessary to increase the purity of the sputtering gas. The oxygen gas and aluminum used as sputtering gas... The gas has a dew point of -40°C or lower, preferably -80°C or lower, more preferably -100°C. The following uses a gas purified to a comfortable temperature of -120°C or lower to obtain metal oxides. This method can prevent moisture and other substances from being absorbed into the membrane as much as possible.

[0100] The conductive film 110 later functions as a pair of electrodes, conductive films 114, 115, and capacitance lines. This results in a functional conductive film 116. Therefore, the conductive film 110 can be used as an electrode. A conductive material is used as appropriate. The conductive film 110 is made of aluminum, titanium, chromium, nickel, From copper, yttrium, zirconium, molybdenum, silver, tantalum, or tungsten A single elemental metal, or an alloy primarily composed of such metal, is used as a single-layer or layered structure. For example, a single-layer structure of an aluminum film containing silicon, or a laminated aluminum film on a titanium film. A two-layer structure, a two-layer structure in which an aluminum film is laminated on a tungsten film, copper-magnesium Two-layer structure with a copper film laminated on an aluminum alloy film, and two-layer structure with a copper film laminated on a titanium film. Structure, a two-layer structure in which a copper film is laminated on a tungsten film, a titanium film or a titanium nitride film, and An aluminum film or copper film is laminated on top of a titanium film or titanium nitride film, and further... A three-layer structure in which a titanium film or titanium nitride film is formed on top of a molybdenum film or molybdenum nitride film. A molybdenum film, and an aluminum film or copper film superimposed on the molybdenum film or molybdenum nitride film. A three-layer structure in which a film is stacked and then a molybdenum film or molybdenum nitride film is formed on top of it, etc. There are also transparent conductive materials containing indium oxide, tin oxide, or zinc oxide. You may do so.

[0101] The conductive film 110 is formed using methods such as sputtering, CVD, or vapor deposition.

[0102] Here, as insulating film 105, a silicon nitride film with a thickness of 400 nm is prepared by the CVD method. Formed. Also, as insulating film 106, a 50 nm thick silicon oxide nitride is formed by CVD. A film is formed. In addition, as the metal oxide film 108, an In-Ga-Zn oxide target is used. Using a sputtering method with (In:Ga:Zn=1:1:1), a 35nm thick I An n-Ga-Zn oxide film is formed. In addition, a conductive film 110 is formed by sputtering. A tungsten film with a thickness of 50 nm and a copper film with a thickness of 300 nm are formed.

[0103] Next, using masks 133 and 134, a portion of the conductive film 110 is etched, and the conductive film Form 111 and 113. Use dry etching and / or wet etching methods. Then, the conductive film 110 can be etched. Next, using masks 133 and 134 Then, a portion of the metal oxide film 108 is etched to form metal oxide films 109a and 109b. To achieve this, a metal oxide film is etched using dry etching and / or wet etching methods. 108 can be etched.

[0104] Here, the conductive film 110 and the metal oxide film 108 are each removed by dry etching. Etch a portion of it.

[0105] Next, masks 133 and 134 are processed. Here, the size of mask 133 is reduced. At the same time, the mask 134 is removed. Here, in an oxygen-containing atmosphere, By plasma treatment in which masks 133 and 134 are exposed to the generated plasma, masks 133 and 1 Process 34. The oxygen-containing atmosphere includes oxygen, ozone, nitrous oxide, and nitrogen dioxide. The atmosphere contains oxidizing gases such as ions. Note that a bias is applied to the substrate 101. Masks 133 and 134 may be exposed to the plasma generated. One example of a device that performs this task is an ashing device.

[0106] As a result, as shown in Figure 3(D), mask 133 is retracted, as are masks 135 and 136. It is possible to form a mask 137 in which mask 134 is retracted. This is possible. Note that in Figure 3(D), the dashed lines represent the masks 133 shown in Figure 3(C). It corresponds to 134.

[0107] Next, using masks 135, 136, and 137, a portion of the conductive films 111 and 113 is removed. The conductive films 114, 115, and 116 are formed by etching, and the metal oxide film 10 Expose portions of 9a and 109b. Dry etching method or / or wet etching method. The conductive films 111, 112, and 113 can be etched using an etching method. Furthermore, the conductive films 111 and 113 are etched, and the metal oxide films 109a and 109b are etched. Do not etch, or etch metal oxide films 109a, 109b over conductive films 111, 113. It is preferable to use conditions with a small intensity rate.

[0108] Here, a portion of the conductive films 111 and 113 is etched using a dry etching method. .

[0109] As a result, as shown in Figure 3(E), the conductive film functions as a pair of electrodes for the transistor. 114, 115, and a conductive film 116 that functions as a capacitance line can be formed. Parts of the metal oxide films 109a and 109b are exposed.

[0110] Through the above process, a single photomask can be used to remove the metal acid containing the channel region of the transistor. The oxide film 109a and conductive films 114 and 115 that function as a pair of electrodes for the transistor, The metal oxide film 109b, which will later become one electrode of the capacitive element, and the conductive material, which will function as a capacitance line. A film 116 can be formed.

[0111] Furthermore, in order to form conductive films 114 and 115 that function as a pair of electrodes for a transistor In the etching process, the regions of the metal oxide films 109a and 109b exposed to the plasma The metal oxide film 109a and the metal acid are damaged and oxygen vacancies are formed. The conductivity of the exposed region in the oxide film 109b increases.

[0112] Next, it is preferable to perform a heat treatment. The temperature of this heat treatment is typically 150°C or higher. Below the upper substrate strain point, preferably 300°C to 500°C, preferably 320°C to 47 Keep the temperature below 0°C.

[0113] The heat treatment can be carried out using an electric furnace, an RTA device, etc. Therefore, heat treatment can be performed at a temperature above the strain point of the substrate for a short period of time. Processing time can be reduced.

[0114] The heat treatment involves nitrogen, oxygen, and ultra-dry air (with a water content of 20 ppm or less, preferably 1 ppm). Air with a podium level of 10 ppb or less (preferably 10 ppb or less), or a noble gas (argon, helium, etc.) The procedure should be carried out under the following conditions. Note that the above-mentioned nitrogen, oxygen, ultra-dry air, or noble gases may contain hydrogen and water. It is preferable that the following are not included.

[0115] Here, after heat treatment at 450°C for 1 hour in a nitrogen atmosphere, in a nitrogen and oxygen atmosphere... Heat treatment at 450°C for 1 hour.

[0116] Furthermore, in conductive films 114, 115, and 116, the metal oxide films 109a and 109b are in contact. In the area, tungsten, titanium, aluminum, copper, molybdenum, chromium, or tungsten. By using a conductive material that readily bonds with oxygen, such as a solid or alloyed metal, a metal oxide film can be formed. Oxygen in 10⁹a and 10⁹b is drawn out to conductive materials that readily combine with oxygen. Tungsten, titanium, aluminum, copper, molybdenum, chromium, or tantalum may be mixed into the oxide films 109a and 109b as a part of constituent elements of a single substance or an alloy. As a result of these processes, in the metal oxide films 109a and 109b, a low-resistance region is formed in the vicinity of a region in contact with conductive films 114, 115, and 116. Since the low-resistance region has high conductivity, the contact resistance between the metal oxide film 109a and the conductive films 114 and 115 can be reduced, which makes it possible to increase the on-current of the transistor. In addition, the contact resistance between the metal oxide film 109b and the conductive film 116 can be reduced, so that the resistance of signal lines and capacitor lines can be reduced.

[0117] Next, as shown in FIG. 4(A), an insulating film 118 is formed. Then, a third photomask is used to perform a photolithography process to form a mask 138 on the insulating film 118.

[0118] The insulating film 118 is preferably formed using an oxide insulating film in order to reduce interface states at the interface with the metal oxide film 108, Typically, the insulating film 118 is formed of silicon oxide , silicon oxynitride, aluminum oxide, hafnium oxide, gallium oxide, or Ga-Z n-based metal oxide, and may be provided as a stacked layer or a single layer.

[0119] Further, as part or all of the insulating film 118, it is preferable to use an oxide insulating film containing more oxygen than that satisfying the stoichiometric composition . In the oxide insulating film containing more oxygen than that satisfying the stoichiometric composition , part of oxygen is desorbed by heating. An oxide insulating film containing more oxygen than that satisfying the stoichiometric composition can be confirmed by TDS analysis to have oxygen The amount of oxygen removed when converted to this is 1.0 × 10⁻⁶. 18 atoms / cm 3 The above, preferably 3. 0 x 10 20 atoms / cm 3 The above describes the oxide insulating film.

[0120] Furthermore, the insulating film 118 preferably has a low defect count, and typically, ESR measurement is used to determine its defect count. Furthermore, the spin density of the signal appearing at g=2.001 originates from the dangling bond of silicon. is 1.5 × 10 18 spins / cm 3 Less than, and even 1 x 10 18 spins / cm 3 Below Bottom, 1×10 17 spins / cm 3 Preferably, the following conditions are met, and even more preferably, the following conditions are met: below the detection limit. .

[0121] The thickness of the insulating film 118 is 30 nm or more and 500 nm or less, preferably 50 nm or more and 400 nm. It should be less than or equal to nm.

[0122] The insulating film 118 is an oxide insulating film containing more oxygen than satisfactorily satisfying the stoichiometric composition. By forming it using a film, the oxygen that is released from the insulating film 118 by heat treatment is removed by metal acid It can be moved to the oxide film 109a. As a result, the contents contained in the metal oxide film 109a It can reduce oxygen deficiency.

[0123] The insulating film 118 can be formed using methods such as sputtering or CVD.

[0124] When forming the insulating film 118 using the CVD method, the raw material gas is a silicon-containing compost. It is preferable to use depositional gases and oxidizing gases. Representative examples of depositional gases containing silicon are Examples include silanes, disilanes, trisilanes, and silane fluorides. Oxidizing gases include: Examples include oxygen, ozone, nitrous oxide, and nitrogen dioxide.

[0125] The insulating film 118 is an oxide insulating film containing more oxygen than satisfies the stoichiometric composition requirement. When forming using this method, the base is placed in the vacuum-evacuated processing chamber of the plasma CVD apparatus. The plate is kept at a temperature of 180°C to 280°C, more preferably 200°C to 240°C. The raw material gas is introduced into the processing chamber, and the pressure inside the processing chamber is set to between 20 Pa and 250 Pa. 0.17 W / cm² is applied to the electrode installed in the processing chamber. 2 More than 0.5W / cm 2 The following are further preferred Or 0.25 W / cm² 2 More than 0.35W / cm 2 The following conditions apply when supplying high-frequency power: This allows for the formation of a silicon oxide film or a silicon oxide nitride film.

[0126] As for the film deposition conditions for the insulating film 118, the above pressure is used in the reaction chamber and the above power density is used in the high-frequency current By supplying power, the decomposition efficiency of the raw material gas in the plasma increases, and the amount of oxygen radicals increases. As the oxidation of the raw material gas progresses, the oxygen content in the insulating film 118 becomes greater than the stoichiometric composition. The number also increases. On the other hand, in films formed at the above temperature, the bonding force between silicon and oxygen Because the bond is weak, some of the oxygen in the film is removed by the subsequent heat treatment. As a result, stoichiometric An insulating film containing more oxygen than satisfies the theoretical composition, and in which some of the oxygen is desorbed upon heating. 118 can be formed.

[0127] Furthermore, the insulating film 118 has a multilayer structure of a first insulating film and a second insulating film, and the first insulating film and is formed using an oxide insulating film capable of permeating oxygen, and as the second insulating film, a n oxide insulating film which contains more oxygen than that satisfying the stoichiometric composition, and from which part of oxygen is desorbed by heating may be formed . With this laminated structure, in the step of forming the second insulating film , the first insulating film serves as a protective film for the metal oxide film. As a result, damage to the metal oxide film can be reduced, and the second insulating film can be formed using high-frequency power with high power density .

[0128] Alternatively, after forming an insulating film by a sputtering method, a CVD method, or the like, oxygen is added to the insulating film , whereby the insulating film 118 can be formed. Note that as a method for adding oxygen to an insulating film , there are an ion doping method, an ion implantation method, and the like. Alternatively, oxygen is added to an insulating film by exposing the insulating film to oxygen-containing plasma generated in an oxidizing gas atmosphere , whereby oxygen can be added to the insulating film .

[0129] Here, as the insulating film 118, silane at a flow rate of 200 sccm and dinitrogen monoxide at a flow rate of 4000 scc m are used as source gases, the pressure in a reaction chamber is 200 Pa, the substrate temperature is 220° C., a 1500 W high-frequency power is supplied to parallel-plate electrodes using a 27.12 MHz high-frequency power source by a plasma CVD method, whereby a silicon oxynitride film with a thickness of 400 nm is formed. Note that the plasma CVD apparatus is a parallel-plate type plasma CVD apparatus having an electrode area of 6000 cm 2 , and when the supplied power is converted into power per unit area (power density), it is 0.25 W / c m 2 . In addition, masks 133 and 135 are formed using a half-tone mask.

[0130] ​Next, a portion of the insulating film 118 is etched using the mask 138, as shown in Figure 4(B). Thus, an insulating film 119 having an opening 151 is formed. In the opening 151, A portion of the oxide film 109b is exposed. Dry etching method or / or wet etching. The insulating film 118 can be etched using the etching method. Next, the mask 138 is removed. do.

[0131] Furthermore, in the etching process for forming the insulating film 119, the metal oxide film 109b In this case, the region exposed to the plasma is damaged, and an oxygen deficiency is formed. Therefore, In the metal oxide film 109b, the conductivity of the region not covered by the insulating film 119 is increased.

[0132] Here, a portion of the insulating film 118 is etched using a dry etching method.

[0133] Next, as shown in Figure 4(C), the insulating film is placed on the metal oxide film 109b and the insulating film 119. Form 120. Next, a photolithography process using a fourth photomask is performed. A mask 139 is formed on the insulating film 120.

[0134] A nitride insulating film is provided as the insulating film 120. The nitride insulating film is silicon nitride. Examples include silicon nitride, aluminum nitride, and aluminum nitride. Nitride insulating films and A nitride insulating film containing hydrogen may then be formed.

[0135] The thickness of the insulating film 120 is 10 nm or more and 400 nm or less, more preferably 50 nm or more. It should be less than 00nm.

[0136] The insulating film 120 can be formed using sputtering, CVD, or other methods. This involves forming an insulating film using methods such as sputtering or CVD, and then adding hydrogen to the insulating film. This may also be done. Furthermore, methods for adding hydrogen to the insulating film include ion doping and ion doping. There are injection methods, etc. Alternatively, plasma generated in a hydrogen-containing gas atmosphere is exposed to an insulating film. This allows hydrogen to be added to the insulating film.

[0137] Here, as the insulating film 120, a plastic is used with silane, ammonia, and nitrogen as raw gases. A silicon nitride film with a thickness of 100 nm is formed using the Zuma CVD method.

[0138] Plasma damage occurs when forming the insulating film 120 on the insulating film 119, causing metal acids Oxygen vacancies are formed in the oxide film 109b. Therefore, in the metal oxide film 109b The conductivity of the region not covered by the insulating film 119 becomes higher. Also, as the insulating film 120, water By using a nitride insulating film containing hydrogen, hydrogen is transferred from the insulating film 120 to the metal oxide film 109b. Movement. When hydrogen moves into an oxygen vacancy, electrons, which are carriers, are generated. As a result, the metal oxide film 109b becomes highly conductive, and the conductive metal oxide film 109c The metal oxide film 109c functions as one electrode of the capacitive element 25.

[0139] Furthermore, since nitride insulating films also function as blocking films for water, hydrogen, etc., insulating film 1 As 20, by providing a nitride insulating film, hydrogen and water from the outside can be introduced into the metal oxide film 109a. This can prevent intrusion by means of such as [unclear text].

[0140] Both the metal oxide film 109a and the metal oxide film 109c are formed on the insulating film 106. However, the impurity concentrations are different. Specifically, compared to metal oxide film 109a, the metal oxide The impurity concentration in film 109c is high. For example, the hydrogen concentration in the metal oxide film 109a is 5 x 10 19 atoms / cm 3 Less than 5 × 10 18 atoms / cm 3 less than Preferably 1 × 10 18 atoms / cm 3 The following is more preferable: 5 x 10 17 ato ms / cm 3 More preferably 1 × 10 16 atoms / cm 3 The following are metals The hydrogen concentration contained in oxide film 109c is 8 × 10⁻⁶. 19 Preferably 1 × 10 20 a toms / cm 3 The above is more comfortable 5x10 20 That's all. Also, metal oxide film 1 Compared to 09a, the hydrogen concentration in the metal oxide film 109c is twice, preferably ten times higher. That's all.

[0141] Furthermore, the metal oxide film 109c has a lower resistivity than the metal oxide film 109a. The resistivity of film 109c is 1 × 10⁻⁶ of the resistivity of metal oxide film 109a. -8 1×10 times more - 1 It is preferable that it be less than a multiple, typically 1 × 10⁻⁶. -3 Ωcm or more, 1 × 10 4 Ωcm not yet More preferably, the resistivity is 1 × 10⁻⁶. -3 Ωcm or more, 1 × 10 -1 It is less than Ωcm That's good.

[0142] Next, a heat treatment may be performed. The temperature of this heat treatment is typically 150°C or higher. Below 0°C, preferably between 300°C and 400°C, preferably between 320°C and 370°C. Let's assume that.

[0143] Nitride insulating films have low diffusion coefficients for hydrogen, water, and oxygen, and block hydrogen, water, and oxygen. It has high locking properties. Also, as the insulating film 119, it contains more oxygen than satisfies the stoichiometric composition. By forming it using an oxide insulating film containing oxygen, in the heat treatment, the metal oxide The diffusion of oxygen contained in film 109a to the outside can be suppressed. The diffusion of oxygen contained in 109a to the outside can be suppressed. As a result, metal oxides The amount of oxygen deficiency in film 109a can be reduced. Furthermore, the external metal oxide film 1 The diffusion of hydrogen, water, etc. into 09a can be suppressed. Therefore, the metal oxide film 109a This reduces the amount of hydrogen, water, etc. As a result, highly reliable transistors can be manufactured. It is possible.

[0144] Here, the material is heated at 350°C for 1 hour in a nitrogen and oxygen atmosphere.

[0145] Next, using mask 139, a portion of the insulating film 119 and 120 is etched, as shown in Figure 4. As shown in D), an opening 152 is formed and the insulating film 120 is etched, Openings 153 and 154 are formed. In addition, the insulating film 120 is formed by this etching. It becomes 121. At the opening 152, a portion of the conductive film 115 is exposed. 3, In 154, a portion of the conductive film 116 is exposed. Dry etching method or / Furthermore, the insulating film 120 can be etched using a wet etching method. Next Remove mask 139.

[0146] Here, a portion of the insulating film 120 is etched using a dry etching method.

[0147] Next, as shown in Figure 5(A), a light-transmitting material is applied to the insulating film 121 and the conductive films 115 and 116. A conductive film 122 is formed. Next, photolithography using a fifth photomask is performed. The process involves forming masks 140 and 141 on the conductive film 122.

[0148] The conductive film 122 later becomes the conductive film 123 that functions as a pixel electrode. The film 122 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 , indium oxide film containing titanium oxide, titanium oxide Indium tin oxide film, indium zinc oxide film, indium with added silicon oxide A film formed from a light-transmitting conductive material such as a tin oxide film can be applied.

[0149] The conductive film 122 is formed using methods such as sputtering, vapor deposition, or coating.

[0150] Here, an ITO film with a thickness of 100 nm is produced as conductive film 122 by sputtering. To form.

[0151] Next, a portion of the conductive film 122 is etched using masks 140 and 141, and the conductive film 1 23 and 124 are formed. Conductive film 123 functions as a pixel electrode. Conductive film 124 is adjacent It has the function of electrically connecting the conductive film 116 formed on the adjacent pixels. 24 functions as a capacitance line, similar to the conductive film 116.

[0152] The conductive film 123 is in contact with the conductive film 115, which functions as a pair of electrodes, and the insulating film 12 It is formed so as to overlap with the metal oxide film 109c via 1. Dry etching method or The conductive film 122 can be etched using the wet etching method. Next, remove masks 140 and 141 (see Figure 5(B)).

[0153] Here, a portion of the conductive film 122 is etched using the wet etching method.

[0154] Through the above process, a conductive film 103 that functions as a gate electrode and a gate insulating film that functions as a gate insulating film are obtained. The insulating film 105, 106, metal oxide film 109a, and metal oxide film 109a are in contact with each other. A transistor 22 having conductive films 114 and 115 that function as a drain electrode and a drain electrode. It is possible to fabricate a pixel. In addition, it comes into contact with the conductive film 115 contained in the transistor 22. A conductive film 123 that functions as an electrode can be formed. Also, it can be formed on the insulating film 106. A capacitive element 25 having a metal oxide film 109c, an insulating film 121, and a conductive film 123. It can be fabricated. That is, a transistor 22 and a conductive film 123 that functions as a pixel electrode. A device substrate having a capacitor element 25 can be fabricated using five photomasks. In this embodiment, a metal oxide film and a conductive film that functions as a source electrode and a drain electrode. Since it is formed using a single photomask, the photomask required to fabricate the element substrate It can reduce the amount of work.

[0155] Furthermore, the semiconductor device shown in this embodiment includes a metal oxide region including the channel region of the transistor. Simultaneously with the formation of the material film, a metal oxide film is formed that will serve as one of the electrodes of the capacitive element. A metal oxide film containing the channel region of the zista, and a metal oxide film that serves as one of the electrodes of the capacitive element. These are composed of the same metallic element. In addition, the conductive film that functions as a pixel electrode is used in addition to the capacitive element. It is used as an electrode. For these reasons, a new conductive film is formed to create a capacitive element. This eliminates the need for a specific process, thus reducing the manufacturing process for the display device. Furthermore, the capacitive element consists of a pair of electric elements. Since both the electrode metal oxide film 109c and the conductive film 123 are translucent, the capacitive element 25 is translucent. As a result, the area occupied by the capacitive element is increased while the aperture ratio of the pixel is increased. It can be improved. Furthermore, it is possible to create display devices with reduced power consumption.

[0156] Note that in Figure 4(B), an opening 151 is provided, but in one embodiment of the present invention, this It is not limited to this. As shown in Figure 13(A), in some cases, or depending on the situation, It is also possible to omit the opening 151.

[0157] In Figure 4(B), the conductive film 124 is connected to the conductive film 116 of the adjacent pixel. However, the embodiments of the present invention are not limited thereto. As shown in Figures 13(B) and 13(C) In some cases, or depending on the circumstances, the conductive film 116 may be extended and connected. It is also possible.

[0158] <Example 1: Regarding the undercoat insulating film> In the transistor shown in this embodiment, the substrate 101 and the gate electrode may be used as needed. An underlayer insulating film can be provided between the conductive films 103 that function as such. These include silicon oxide, silicon oxide nitride, silicon nitride, silicon oxide nitride, and gallium oxide. Using hafnium oxide, yttrium oxide, aluminum oxide, aluminum nitride oxide, etc. It can be formed by using silicon nitride, gallium oxide, and acid as the underlying insulating film. By forming using hafnium oxide, yttrium oxide, aluminum oxide, etc., the substrate 1 Diffusion of impurities, typically alkali metals, water, and hydrogen, from 01 to the metal oxide film 109a. It can be suppressed.

[0159] The underlying insulating film can be formed by sputtering, CVD, or other methods.

[0160] <Modification Example 2: Regarding the gate insulating film> The insulating film 105 formed with a nitride insulating film is made of a first nitride insulating film with few defects, and water A laminated structure of a second nitride insulating film with high primary blocking properties can be achieved. Gate insulation By providing a nitride insulating film with few defects as the film, the dielectric breakdown voltage of the gate insulating film is improved. It can also be used as a gate insulating film, specifically a nitride insulating film with high hydrogen blocking properties. By providing this, hydrogen from the conductive film 103 and insulating film 105, which function as gate electrodes, This prevents migration to the metal oxide film 109a.

[0161] Alternatively, the insulating film 105 formed with a nitride insulating film has high impurity blocking properties. A first nitride insulating film, a second nitride insulating film with few defects, and high hydrogen blocking properties. The second nitride insulating film is stacked sequentially from the conductive film 103 side, which functions as the gate electrode. A layered structure can be formed. As a gate insulating film, a first layer with high impurity blocking properties is used. By providing a nitride insulating film, impurities from the conductive film 103, which functions as a gate electrode, Typically, hydrogen, nitrogen, alkali metals, or alkaline earth metals form the metal oxide film 10 This prevents the device from moving to 9a.

[0162] <Modification 3: Regarding metal oxide films> <About metal oxide films> When hydrogen is added to an oxide semiconductor in which oxygen vacancies have formed, hydrogen enters the oxygen vacancy site. A donor level is formed near the conduction band. As a result, the oxide semiconductor becomes highly conductive. It becomes conductive. An oxide semiconductor that has been made conductive can be called an oxide conductor. Generally Oxide semiconductors have a large energy gap, which allows them to transmit visible light. On the other hand, oxide conductors are oxide semiconductors that have donor levels near the conduction band. Therefore Therefore, the influence of absorption by the donor level is small, and the transparency to visible light is similar to that of oxide semiconductors. It is photosensitive.

[0163] Here, a film formed from an oxide semiconductor, such as the metal oxide film 109a ( Below, we have an oxide semiconductor film (OS). ) and a metal oxide film 10⁹c, In a film formed of an oxide conductor (hereinafter referred to as an oxide conductor film (OC)), the resistance The temperature dependence of the rate will be explained using Figure 17. In Figure 17, the horizontal axis is the measured temperature. The graph shows resistivity on the vertical axis. The measurement results for oxide semiconductor films (OS) are indicated by circles, and acid The measurement results for the occlusive oxide (OC) film are indicated by square marks.

[0164] Furthermore, for samples containing oxide semiconductor films (OS), the atomic ratio is In:Ga on a glass substrate. Thickness A 35nm In-Ga-Zn oxide film is formed, with an atomic ratio of In:Ga:Zn = 1:4 A 20nm thick In- A Ga-Zn oxide film is formed, then heat-treated in a nitrogen atmosphere at 450°C, followed by a nitrogen atmosphere at 450°C. The silicon oxide nitride film is then heated in an oxygen mixed gas atmosphere and further processed by plasma CVD. It was formed and manufactured.

[0165] Furthermore, samples containing oxide conductive films (OCs) are prepared on a glass substrate with an atomic ratio of In:Ga A sputtering method using a sputtering target with Zn=1:1:1 is used to create a thickness of 1 After forming a 00nm In-Ga-Zn oxide film and heat-treating it in a nitrogen atmosphere at 450°C The material is then heated in a mixed gas atmosphere of nitrogen and oxygen at 450°C and subjected to silica nitride by plasma CVD. It was fabricated by forming a film.

[0166] As can be seen from Figure 13, the temperature dependence of resistivity in an oxide conductive film (OC) is acid The temperature dependence of resistivity is smaller than that of oxide semiconductor films (OS). Typically, above 80K. The rate of change in resistivity of oxide conductive films (OC) below 290K is less than ±20%. Alternatively, the rate of change in resistivity between 150K and 250K is less than ±10%. In other words, oxide conductors are degenerate semiconductors in which the conduction band edge and the Fermi level coincide or are approximately the same. It is presumed that this is the case. For this reason, oxide conductive films are used in resistive elements, wiring, and capacitive elements. It can be used for electrodes, pixel electrodes, common electrodes, etc.

[0167] <Regarding oxide semiconductor films and metal oxide films> Next, regarding one embodiment applicable to metal oxide films and oxide semiconductor films having semiconductor properties: This will be explained. Here, as a representative example, an oxide semiconductor film will be used for the explanation, but oxides will be used as appropriate. The structure of semiconductor films can be applied to metal oxide films.

[0168] The oxide semiconductor film is preferably composed of a CAAC-OS film. The S film exhibits c-axis orientation, and clear grain boundaries (also known as grain boundaries) can be observed. This is not possible. As a result, in a channel etch type transistor, a pair of electrodes The amount of over-etching of the oxide semiconductor film during formation is small. As a result, the oxide semiconductor By constructing the body membrane with a CAAC-OS film, a channel-etch type transistor is fabricated. This is possible. Note that in channel etch transistors, the distance between a pair of electrodes, i.e., the channel The channel length is set to a channel length of 0.5 μm or more and 6.5 μm or less, preferably greater than 1 μm and 6 It is possible to reduce the size to less than a micrometer.

[0169] Furthermore, oxide semiconductor films are oxide semiconductors with a single-crystal structure (hereinafter referred to as single-crystal oxide semiconductors). (U.), polycrystalline oxide semiconductors (hereinafter referred to as polycrystalline oxide semiconductors), and microcrystals It may be composed of one or more oxide semiconductors of a specific structure (hereinafter referred to as microcrystalline oxide semiconductors). Below are CAAC-OS, single-crystal oxide semiconductors, polycrystalline oxide semiconductors, and microcrystalline oxide semiconductors. Let's explain conductors.

[0170] <caac-os> CAAC-OS film is an oxide semiconductor film having multiple crystalline regions. The crystalline portion contained in the AC-OS film has c-axis orientation. In the planar TEM image, CAA The area of ​​the crystalline portion contained in the C-OS film is 2500 nm 2 More preferably 5 μm 2 Below More preferably 1000 μm 2 That concludes the report. Furthermore, in the cross-sectional TEM image, the crystal Having 50% or more, preferably 80% or more, and more preferably 95% or more of the part, It becomes a thin film with physical properties similar to those of a crystal.

[0171] CAAC-OS film is examined using a transmission electron microscope (TEM). Observation with a tron ​​microscope reveals clear boundaries between distinct crystalline regions. Therefore, grain boundaries (also called crystal grain boundaries) cannot be identified. Therefore, CAAC-OS films are less susceptible to a decrease in electron mobility caused by grain boundaries. .

[0172] The CAAC-OS film was observed by TEM from a direction roughly parallel to the sample surface (cross-sectional TEM view). (Inference) It can be confirmed that in the crystalline part, metal atoms are arranged in layers. Each of these layers has a concave surface on the surface (also called the surface to be formed) or upper surface that forms the CAAC-OS film. It has a convex shape and is arranged parallel to the surface or top surface of the CAAC-OS film. In this specification, "parallel" means that two straight lines are aligned at an angle of -10° or more and 10° or less. This refers to the state in which something is placed. Therefore, it also includes cases where the angle is between -5° and 5°. Also, "vertical" "A straight line is a state in which two straight lines are positioned at an angle of 80° to 100°. Therefore, This also includes cases where the angle is between 85° and 95°.

[0173] On the other hand, the CAAC-OS film was observed by TEM from a direction roughly perpendicular to the sample surface (plane T). EM observation reveals that in the crystalline region, metal atoms are arranged in a triangular or hexagonal shape. This can be confirmed. However, no regularity is observed in the arrangement of metal atoms between different crystalline regions. do not have.

[0174] Furthermore, when electron diffraction is performed on the CAAC-OS film, oriented spots (bright spots) are observed. This is observed.

[0175] Cross-sectional TEM observation and planar TEM observation revealed that the crystalline portion of the CAAC-OS film exhibits orientation. It can be seen that this is the case.

[0176] X-ray diffraction (XRD) of CAAC-OS film Structural analysis using the instrument reveals that the CAAC-OS film can be analyzed by an out-of-plane method. In the analysis, a peak may appear near a diffraction angle (2θ) of 31°. This peak is I Since it is attributed to the (00x) plane (where x is an integer) of the nGaZn oxide crystal, CAAC- The crystals of the OS film have c-axis orientation, with the c-axis pointing in a direction approximately perpendicular to the surface to be formed or the upper surface. It can be confirmed that they are there.

[0177] On the other hand, in the CAAC-OS film, X-rays are incident from a direction approximately perpendicular to the c-axis in an in-p In analysis using the lane method, a peak may appear when 2θ is around 56°. This is attributed to the (110) plane of the InGaZn oxide crystal. For a crystalline oxide semiconductor film, fix 2θ to around 56° and set the normal vector of the sample surface to axis (φ When the analysis (φ scan) is performed while rotating the sample as the axis, the (110) plane is equivalent to the (110) plane. Six peaks attributable to the crystal plane are observed. In contrast, in the case of the CAAC-OS film, 2 Even when θ is fixed near 56° and φ is scanned, no clear peak appears.

[0178] From the above, it can be concluded that in CAAC-OS films, the orientation of the a-axis and b-axis between different crystalline regions is Although irregular, it has c-axis orientation, and the c-axis is parallel to the normal vector of the formed surface or the upper surface. It can be seen that it is oriented in a specific direction. Therefore, the layered structure confirmed by the aforementioned cross-sectional TEM observation is Each layer of arranged metal atoms is a plane parallel to the ab-plane of the crystal.

[0179] Furthermore, the crystalline portion is formed when the CAAC-OS film is deposited, or during crystallization treatments such as heat treatment. It is formed when the process is carried out. As mentioned above, the c-axis of the crystalline portion is the surface on which the CAAC-OS film is formed. Alternatively, it is oriented in a direction parallel to the normal vector of the upper surface. Therefore, for example, CAAC-OS film When the shape is altered by etching or other means, the c-axis of the crystalline portion is covered by the CAAC-OS film. The normal vector may not be parallel to the forming surface or the top surface.

[0180] Furthermore, the degree of crystallinity in the CAAC-OS film does not need to be uniform. For example, CAAC-OS When the crystalline portion of the film is formed by crystal growth from near the upper surface of the CAAC-OS film, The region near the surface may have a higher degree of crystallinity than the region near the surface being formed. Also, CA When impurities are added to an AC-OS film, the degree of crystallinity in the region where the impurities are added changes, and Regions with varying degrees of crystallinity may also be formed.

[0181] Furthermore, in the out-of-plane analysis of the CAAC-OS film, 2θ was 31° In addition to the nearby peak, a peak may also appear when 2θ is near 36°. The adjacent peak indicates that a portion of the CAAC-OS film contains crystalline regions that do not exhibit c-axis orientation. This indicates that the CAAC-OS film shows a peak around 2θ = 31° and 2θ = 36°. It is preferable that no peaks appear in the vicinity.

[0182] CAAC-OS films are oxide semiconductor films with low impurity concentrations. The impurities include hydrogen and carbon. These are elements other than the main components of oxide semiconductor films, such as silicon and transition metal elements. In particular, silicon Elements such as condensate, which have a stronger bonding force with oxygen than the metal elements that make up oxide semiconductor films, are acidic. By removing oxygen from the oxide semiconductor film, the atomic arrangement of the oxide semiconductor film is disrupted, reducing its crystallinity. This is a contributing factor. Also, heavy metals such as iron and nickel, argon, and carbon dioxide have a high atomic ratio. Because of its large diameter (or molecular radius), when it is contained within an oxide semiconductor film, the oxide semiconductor film This disrupts the atomic arrangement and reduces crystallinity. Pure substances can act as carrier traps or carrier sources.

[0183] Furthermore, CAAC-OS films are oxide semiconductor films with a low defect level density. For example, oxidation Oxygen vacancies in semiconductor films can act as carrier traps or capture hydrogen. This can sometimes become a source of carrier transmission.

[0184] A low impurity concentration and low defect level density (few oxygen vacancies) are referred to as high-purity intrinsic or This is essentially called high-purity intrinsic. Oxide semiconductors that are high-purity intrinsic or substantially high-purity intrinsic. Because the membrane has fewer carrier sources, the carrier density can be lowered. Therefore, A transistor using this oxide semiconductor film exhibits electrical characteristics such as a negative threshold voltage ( - Also called Marieion.) It rarely becomes high purity genuine or substantially high purity. Intrinsic oxide semiconductor films have few carrier traps. Therefore, the oxide semiconductor... Transistors using film have small variations in electrical characteristics and are highly reliable. Furthermore, the charge trapped in the carrier trap of the oxide semiconductor film requires time to be released. It can last for a long time and behave as if it were a fixed charge. Therefore, when the impurity concentration is high... Furthermore, transistors using oxide semiconductor films with a high defect level density exhibit unstable electrical properties. There are cases where this occurs.

[0185] Furthermore, transistors using CAAC-OS films exhibit electrical properties when irradiated with visible light or ultraviolet light. Sexual variation is small.

[0186] <Single-crystal oxide semiconductor> Single-crystal oxide semiconductor films have low impurity concentrations and low defect level densities (few oxygen vacancies). It is an oxide semiconductor film. Therefore, the carrier density can be lowered. Transistors using crystalline oxide semiconductor films rarely exhibit normally-on electrical properties. No. Also, single-crystal oxide semiconductor films have a low impurity concentration and a low defect level density, so Carrier traps may be reduced. Therefore, using a single-crystal oxide semiconductor film ZISTA transistors exhibit less variation in electrical characteristics, resulting in highly reliable transistors.

[0187] Furthermore, oxide semiconductor films have higher density when they have fewer defects. Also, oxide semiconductor films Higher crystallinity results in higher density. Also, oxide semiconductor films have a low concentration of impurities such as hydrogen. The density increases. Single-crystal oxide semiconductor films have a higher density than CAAC-OS films. Furthermore, CAAC-OS films have a higher density than microcrystalline oxide semiconductor films. Conductive films have a higher density than microcrystalline oxide semiconductor films. Also, microcrystalline oxide semiconductor films are non It has a higher density than crystalline oxide semiconductor films.

[0188] <Polycrystalline oxide semiconductors> In polycrystalline oxide semiconductor films, the crystal grains can be identified by observation using high-resolution TEM. This can be done. The crystal grains contained in the polycrystalline oxide semiconductor film can be observed, for example, by high-resolution TEM. In the observed image, the ranges are 2nm to 300nm, 3nm to 100nm, or 5nm to 50nm. The particle size is often less than m. In addition, polycrystalline oxide semiconductor films are obtained by high-resolution TEM. In some cases, grain boundaries can be identified in the observed image.

[0189] A polycrystalline oxide semiconductor film has multiple crystal grains, and between these multiple crystal grains, the crystals The positions may differ. Also, when using an XRD device on a polycrystalline oxide semiconductor film... Structural analysis reveals, for example, a polycrystalline oxide semiconductor film having InGaZnO4 crystals. Analysis using the t-of-plane method showed a peak near 31° for 2θ and a peak near 36° for 2θ. A peak, or any other peak, may appear.

[0190] Polycrystalline oxide semiconductor films have high crystallinity, and therefore may have high electron mobility. Therefore, transistors using polycrystalline oxide semiconductor films have high field-effect mobility. However, polycrystalline oxide semiconductor films may have impurities segregated at the grain boundaries. In polycrystalline oxide semiconductor films, the grain boundaries become defect levels. Because these can become carrier traps or carrier sources, polycrystalline oxide semiconductor films are used. The transistors used showed variations in electrical characteristics compared to transistors using CAAC-OS film. This can result in large, unreliable transistors.

[0191] <Microcrystalline oxide semiconductor> Microcrystalline oxide semiconductor films can be clearly observed using TEM. In some cases, this may not be possible. The crystalline portion contained in the microcrystalline oxide semiconductor film is between 1 nm and 100 nm. They are often smaller than 1 nm, or between 1 nm and 10 nm in size. In particular, between 1 nm and 10 nm Nanocrystals (nc: nanocrystals) are microcrystals of a size of 1 nm or less, or between 1 nm and 3 nm. An oxide semiconductor film having tal is made nc-OS (nanocrystalline O It is called an xide Semiconductor film. Also, an nc-OS film is, for example, T In some cases, grain boundaries may not be clearly visible in images obtained using EM (Electromagnetic Wave) imaging.

[0192] nc-OS films are used in minute regions (for example, regions between 1 nm and 10 nm, especially regions between 1 nm and 10 nm). The atomic arrangement has periodicity in the region of 3 nm or less. In addition, the nc-OS film is different There is no regularity in the crystal orientation between the crystalline regions. Therefore, no orientation is observed throughout the film. Therefore, depending on the analytical method, nc-OS films may be indistinguishable from amorphous oxide semiconductor films. There are cases where this occurs. For example, XRD using X-rays with a diameter larger than that of the crystalline region on an nc-OS film. When structural analysis is performed using the apparatus, the out-of-plane method analyzes the crystal planes. The peaks shown are not detected. Also, for the nc-OS film, a diameter larger than that of the crystalline region (for example) When electron diffraction (also called limited-field electron diffraction) is performed using an electron beam of 50 nm or more, A diffraction pattern resembling a halo pattern is observed. On the other hand, for nc-OS films, crystal A probe diameter (for example, between 1 nm and 30 nm) that is close to the size of the part or smaller than the crystal part. When electron diffraction using a sub-beam (also called nanobeam electron diffraction) is performed, a spot can be observed. It is done. Also, when nanobeam electron diffraction is performed on nc-OS, it forms a circular pattern (phosphorus). In some cases, a region of high brightness (in a slant) may be observed. Also, when the nanobeam is applied to nc-OS... When sub-ray diffraction is performed, multiple spots may be observed within a ring-shaped region.

[0193] nc-OS films are oxide semiconductor films with higher orderliness than amorphous oxide semiconductor films. Therefore, nc-OS films have a lower defect level density than amorphous oxide semiconductor films. However, Furthermore, the nc-OS film does not show any regularity in crystal orientation between different crystalline regions. Therefore, nc- OS films have a higher defect level density compared to CAAC-OS films.

[0194] Note that the configurations and methods shown in this embodiment may differ from those shown in other embodiments. It can be used in appropriate combinations.

[0195] (Embodiment 2) In this embodiment, a method for manufacturing an element substrate of a display device that differs from that of Embodiment 1 is shown in Figure This will be explained using a surface. This embodiment, like Embodiment 1, has a gold channel region. A single photomask contains an oxide film and conductive films that function as source and drain electrodes. It is formed using. On the other hand, in this embodiment, the configuration of the conductive film that functions as a capacitance line is implemented It differs from Form 1.

[0196] This section describes a specific example of a component substrate for a liquid crystal display device that uses liquid crystal elements in pixel 13. Here, Figure 6 shows a top view of pixel 13, as shown in Figure 1(B).

[0197] In Figure 6, pixel 13 has a portion of the metal oxide film 109c that functions as a capacitance line. The metal oxide films 109c provided on adjacent pixels are connected by a conductive film 173.

[0198] In the pixel 13 shown in Figure 6, an opening is provided in the insulating film 119 (see Figure 7(A)). In 171 and 172, the metal oxide film 109c and the conductive film 12 function as pixel electrodes. The conductive film 173 formed simultaneously with 3 connects. The metal oxide film 109c is connected to the opening 151 (See Figure 4(B).) Because it comes into contact with the insulating film formed using a nitride insulating film, It has electrical properties. As a result, the metal oxide film 109c functions as a capacitance line, and It functions as one of the electrodes of a quantitative element.

[0199] The capacitive element 25 consists of a conductive metal oxide film 109c and an insulating film 121 (see Figure 7(B)). It consists of a conductive film 123 that functions as a light source and a pixel electrode. That is, a metal oxide. The film 109c connects to the conductive film 173, thereby connecting to one electrode of the capacitive element in each pixel. Here, a conductive metal oxide film 109c) can be brought to the same potential.

[0200] The pixel 13 shown in this embodiment is formed simultaneously with the conductive films 114 and 115 as capacitance lines. It does not use a conductive film. Because conductive films 114 and 115 have light-shielding properties, the aperture ratio of the pixels is It can be improved.

[0201] Next, using the cross-sectional view of the dashed line AB and the cross-sectional view of the dashed line CD shown in Figure 6, the display system The method for fabricating the element substrate will be explained below.

[0202] Using the same process as in Embodiment 1, the first to third photomasks are used. As a result of this process, a conductive gate electrode, as shown in Figure 7(A), is placed on the substrate 101, which functions as a gate electrode. Film 103, insulating film 105, 106, metal oxide film 109a, 109c, conductive film 114, 1 15. Insulating film 119 and insulating film 120 are formed. In this embodiment, No film 116 is formed. Also, a metal oxide film 109a is formed using a second photomask. Since 109c and conductive films 114 and 115 can be formed, the manufacturing process of the element substrate This can reduce the number of photomasks required.

[0203] Next, a photolithography process using a fourth photomask is performed on the insulating film 120. After forming the mask, the insulating films 119 and 120 are etched using the mask to create a conductive film. An opening 152 is formed to expose the film 115, and the insulating film 120 is etched. Openings 171 and 172 are formed to expose a conductive metal oxide film (see Figure 7(B)). (Illuminate.) Furthermore, the insulating film 121 can be formed by this etching process.

[0204] Next, the exposed portions of the conductive metal oxide film 109c and the conductive film 115, and the insulating film. A translucent conductive film is formed on 121. Next, a photomask is used to form a film. A mask is formed on a light-transmitting conductive film using a trisography process, and the mask is used By etching a light-transmitting conductive film, a conductive film 123 that functions as a pixel electrode is produced. And a conductive film 173 that functions as a capacitance line is formed. The conductive film 173 is shaped to form adjacent pixels. The resulting conductive metal oxide film 109c has the function of electrically connecting. Next, remove the mask (see Figure 7(C)).

[0205] Through the above process, the transistor 22 and the capacitive element 25 can be manufactured. Through the above process, it is possible to fabricate an element substrate having pixels with a higher aperture ratio. .

[0206] Note that the configurations and methods shown in this embodiment may differ from those shown in other embodiments. It can be used in appropriate combinations.

[0207] (Embodiment 3) This embodiment is an example of a transverse field system called FFS (Fringe Field Switch). This will be explained using the pixel structure of a liquid crystal display device in tching mode.

[0208] The FFS mode liquid crystal display device shown in this embodiment has a striped common electrode, and the electrode By applying the electric field generated at the pixel electrode and common electrode to the liquid crystal in between, the orientation of the liquid crystal is changed. Control. A liquid crystal display in FFS mode has a high aperture ratio and can obtain a wide viewing angle. Cut.

[0209] Here, Figure 8 shows a top view of pixel 13, as shown in Figure 1(B).

[0210] The pixels 13 shown in Figure 8 each have one metal oxide film 183. 83 has conductive films 181 and 182 that function as source and drain electrodes. The conductive film 181 also functions as a signal line. The conductive film 181 is separated for each pixel. It is also provided with conductive films 181 that electrically connect adjacent pixels. 87 is provided on the conductive film 181 via an insulating film (not shown). The conductive film 187 is At apertures 184 and 185, it connects to the conductive film 181. Also, across multiple pixels, A conductive film 186 that functions as a striped common electrode is provided. Conductive film 187 and conductive film 1 86 is formed simultaneously.

[0211] In the display device shown in this embodiment, the conductive film 186 that functions as a common electrode is a base The conductive films 181, 187, and , which are not formed over the entire surface of the plate but are striped, function as signal lines. The area overlapping with the conductive film 103, which functions as a scanning line, is reduced. As a result, the conductive film 10 Occurs between 3 and conductive film 186, and between conductive films 181, 187 and conductive film 186. This can reduce the parasitic capacity.

[0212] Next, using the cross-sectional view of the dashed line AB and the cross-sectional view of the dashed line EF shown in Figure 8, the display system The method for fabricating the element substrate will be explained below.

[0213] Following the same steps as in Embodiment 1, and using the first photomask, Figure 9(A As shown in ( ), a conductive film 103 that functions as a gate electrode is formed on the substrate 101. Next Then, on the substrate 101 and the conductive film 103, in the same manner as in Embodiment 1, insulating films 105, 106, A metal oxide film 108 and a conductive film 110 are formed.

[0214] Next, using the second photomask shown in Embodiment 1, the process shown in Figure 9(B) is carried out. Thus, a metal oxide film 183 and conductive films 181 and 182 are formed. The conductive film 181 is implemented Similar to the conductive film 114 shown in Embodiment 1, one of the source and drain electrodes of the transistor It functions as both a line and a signal line. The conductive film 182 is shown in Embodiment 1. Similar to the conductive film 115, it functions as the other of the source electrode and drain electrode of the transistor. Here, using a second photomask, the metal oxide film 183 and the conductive film 181, Because 82 can be formed, the number of photomasks in the manufacturing process of the element substrate can be reduced. can.

[0215] Next, the process using the third photomask shown in Embodiment 1 is performed to create the opening 151. After forming the insulating film 119, the insulating film 120 is applied to the metal oxide film 183 and the insulating film 119. It forms (see Figure 9(C)).

[0216] In the metal oxide film 183, the region 191 in contact with the insulating film 120 is the metal oxide film 10 Similar to 9c, conductivity increases. As a result, it functions as a pixel electrode. On the other hand, insulating film 11 9 is formed using an oxide insulating film. Therefore, in the metal oxide film 183, The region in contact with 119 has a low interface state density with the insulating film 119. Furthermore, the insulating film 119 Formed using an oxide insulating film containing more oxygen than satisfactorily satisfying the stoichiometric composition. As a result, the oxygen contained in the insulating film 119 moves to the metal oxide film 183, so in region 192 This makes it possible to reduce the oxygen deficiency content. As a result, the metal oxide film 183 Furthermore, the region 192 in contact with the insulating film 119 functions as a channel region. In the physical film 183, the region in contact with the conductive films 181 and 182 becomes a low-resistance region.

[0217] Furthermore, when forming the insulating film 119 having an opening 151, the edges of the opening 151 and scanning The distance to the conductive film that functions as a line, and the end of the opening 151 and the conductive film that functions as a signal line. Let's assume the distance from film 181 is greater than 1.5 μm, and further greater than 2 μm, respectively. This is preferable. In the metal oxide film 183, the region in contact with the insulating film 120 is oxygen-deficient. Alternatively, the presence of impurities increases conductivity, but even in the region adjacent to that region, conductivity increases. The electrical properties increase. This is because impurities diffuse laterally, causing the metal oxide film 183 to develop an odor. This is because impurities are also present in the region that is not in contact with the insulating film 121, resulting in lower resistance. Therefore, the distance between the edge of the opening 151 and the conductive film that functions as a scanning line is set to 1.5 By making it larger than μm, and even larger than 2 μm, the channel of transistor 22 This prevents the region from becoming too low in resistance and allows for the creation of a transistor with normally-off characteristics. It can be manufactured. Also, the end of the opening 151 and the conductive film 181 which functions as a signal line By making the distance greater than 1.5 μm, and even greater than 2 μm, the signal line can be used as A functional conductive film 181 and a region 19 in the metal oxide film 183 that functions as a pixel electrode. The voltages of 1 and 1 do not affect each other, preventing display malfunctions.

[0218] Next, a photolithography process using a fourth photomask is performed on the insulating film 121. After forming the mask, the insulating films 119 and 120 are etched using the mask to create a conductive film. Openings 184 and 185 are formed to expose the film 181, and the insulating film 121 is formed. (See Figure 10(A).)

[0219] Next, a light-transmitting conductive film is formed on the exposed portion of the conductive film 181 and on the insulating film 121. Next, a photolithography process using a fifth photomask is performed to obtain a translucent material. A mask is formed on a conductive film, and the transparent conductive film is etched using the mask. Then, a conductive film 186 that functions as a common electrode is formed, and also functions as a signal line. A conductive film 187 is formed. The conductive film 187 transmits the conductive film 181 provided on adjacent pixels. Connect electrically. After this, remove the mask (see Figure 10(B)).

[0220] Through the above process, the transistor 22 and the capacitive element 25 can be manufactured. Through the above process, it is possible to fabricate an element substrate having pixels with a higher aperture ratio. Furthermore, it is possible to manufacture liquid crystal display devices in FFS mode.

[0221] Note that the configurations and methods shown in this embodiment may differ from those shown in other embodiments. It can be used in appropriate combinations.

[0222] (Embodiment 4) In this embodiment, compared to Embodiments 1 to 3, the amount of defects in the metal oxide film Refer to the drawings for a semiconductor device having a transistor that can further reduce [the amount of power required]. Let me explain. The transistor described in this embodiment is compared to those in Embodiments 1 and 2. In contrast, instead of a single metal oxide film, a multilayer film having multiple metal oxide films is provided. The point is different.

[0223] Figure 11 shows the transistors of the semiconductor device, as shown by the dashed lines AB and CD in Figure 2. This is a cross-sectional view between the dashed lines AB and CD.

[0224] The transistor 22b shown in Figure 11(A) has multilayer films 250a and 250 on the insulating film 106. b is present. The multilayer film 250a has a first metal oxide film 251a in contact with the insulating film 106, and The second metal oxide film 252a is in contact with the first metal oxide film 251a and the insulating film 119. It has.

[0225] As shown in Figure 11(A), the multilayer film 250b provided on the insulating film 106 is used as a capacitive electrode. The multilayer film 250b is in contact with the insulating film 107b, and It has a first metal oxide film 251b and a second metal oxide film 252b in contact with the insulating film 119. do.

[0226] The second metal oxide films 252a and 252b are formed by overlapping the first metal oxide films 251a and 251b. It is a metal oxide film composed of one or more constituent elements. Therefore, the first metal oxide At the interface between the material films 251a and 251b and the second metal oxide films 252a and 252b, Surface scattering is less likely to occur. Therefore, carrier movement is not hindered at the interface, The field-effect mobility of the transistor increases.

[0227] The first metal oxide films 251a, 251b and the second metal oxide films 252a, 252b are Typical examples include In-Ga oxide, In-Zn oxide, and In-M-Zn oxide (where M is Al). These are Ga, Ti, Y, Zr, La, Ce, or Nd.

[0228] Furthermore, the second metal oxide films 252a and 252b are the same as the first metal oxide films 251a and 25 The energy at the lower end of the conduction band is closer to the vacuum level than that of 1b, and is typically found in the second type of metal oxide. The energy at the lower end of the conduction band of films 252a and 252b, and the energy of the first metal oxide films 251a and 2 The energy difference from the lower end of the conduction band 51b is 0.05 eV or more, 0.07 eV or more, 0 0.1eV or higher, or 0.15eV or higher and 2eV or lower, 1eV or lower, 0.5eV or lower or less than 0.4 eV. That is, the electron parent of the second metal oxide films 252a and 252b. The difference between the summing force and the electron affinity of the first metal oxide films 251a and 251b is 0.05 eV or less. Above, 0.07 eV or higher, 0.1 eV or higher, or 0.15 eV or higher and 2 eV or lower, 1 It is less than or equal to eV, less than or equal to 0.5 eV, or less than or equal to 0.4 eV.

[0229] The first metal oxide films 251a, 251b and the second metal oxide films 252a, 252b are The inclusion of In is preferable because it increases carrier mobility (electron mobility).

[0230] As the second metal oxide films 252a and 252b, Al, Ga, Ti, Y, Zr, La, Having Ce or Nd in a higher atomic ratio than In may have the following effects: (1) Increase the energy gap of the second metal oxide films 252a and 252b. (2) Reduce the electron affinity of the second metal oxide films 252a and 252b. (3) External (4) Compared with the first metal oxide films 251a and 251b , the insulating properties become higher. (5) Ga, Y, Zr, La, Ce, or Nd are bonded with oxygen. Because it is a strong metallic element, oxygen deficiency is less likely to occur.

[0231] When the first metal oxide films 251a and 251b are In-M-Zn oxides, In and When the sum of In and M is taken as 100 atomic%, the atomic ratio of In to M is preferably I The atomic ratio of n to M is preferably such that In is greater than 25 atomic%, and M is 75 atomic%. Less than mic%, more preferably In is greater than 34atomic%, and M is 66atomic%. It should be less than mic%.

[0232] When the second metal oxide films 252a and 252b are In-M-Zn oxides, In and When the sum of In and M is taken as 100 atomic%, the atomic ratio of In to M is preferably I n is less than 50 atomic%, M is greater than 50 atomic%, more preferably, Assume that In is less than 25 atomic percent and M is greater than 75 atomic percent.

[0233] Furthermore, the first metal oxide films 251a, 251b and the second metal oxide films 252a, 25 2b is In-M-Zn oxide M (where M is Al, Ga, Ti, Y, Zr, La, Ce, In the case of Nd, compared to the first metal oxide films 251a and 251b, the second metal oxide M(Al, Ga, Ti, Y, Zr, La, Ce, and) contained in the material films 252a and 252b, The atomic ratio of Nd is large, and typically it is present in the first metal oxide films 251a and 251b. Compared to the above atoms that are found, 1.5 times or more, preferably 2 times or more, and more preferably 3 times This represents a high atomic ratio.

[0234] Furthermore, the first metal oxide films 251a, 251b and the second metal oxide films 252a, 25 2b is In-M-Zn oxide (where M is Al, Ga, Ti, Y, Zr, La, Ce, and In the case of Nd, the second metal oxide films 252a and 252b are In:M:Zn=x1:y1 :z1[atomic ratio], first metal oxide films 251a, 251b are In:M:Zn=x2: If y2:z2 [atomic ratio], then y1 / x1 is greater than y2 / x2, preferably, y1 / x1 is 1.5 times or more than y2 / x2. More preferably, y1 / x1 is y is at least twice larger than 2 / x2, more preferably y1 / x1 is at least three times larger than y2 / x2 .

[0235] When the first metal oxide films 251a and 251b are In-M-Zn oxides (where M is Al, Ga, Ti, Y, Zr, La, Ce, or Nd), in a target used for forming the first metal oxide films 251a and 25 1b, when the atomic ratio of metal elements is In:M:Zn =x1:y1:z1 、 x1 / y1 is not less than 1 / 3 and not more than 6, further not less than 1 and not more than 6 , and z1 / y1 is preferably not less than 1 / 3 and not more than 6, further preferably not less than 1 and not more than 6 . By setting z1 / y1 to be not less than 1 and not more than 6, CAAC-OS films are easily formed as the first metal oxide films 251a and 25 1b. Representative examples of the atomic ratio of metal elements in the target include In:M:Zn=1:1:1, In:M:Zn=1:1:1.2, In :M:Zn=3:1:2, and the like.

[0236] When the second metal oxide films 252a and 252b are In-M-Zn oxides (where M is Ga, Y, Z r, La, Ce, or Nd), in a target used for forming the second metal oxide films 252a and 252b , when the atomic ratio of metal elements is In:M:Zn=x2:y2 :z2 、 x2 / y2<x1 / y1, and z2 / y2 is preferably not less than 1 / 3 and not more than 6, further preferably not less than 1 and not more than 6. By setting z2 / y2 to be not less than 1 and not more than 6 , CAAC-OS films are easily formed as the second metal oxide films 252a and 252b . Representative examples of the atomic ratio of metal elements in the target include In:M:Zn=1:3:2 , In:M:Zn=1:3:4, In:M:Zn=1:3:6, In:M:Zn=1:3 There are 8, etc.

[0237] Furthermore, the first metal oxide films 251a, 251b and the second metal oxide films 252a, 25 The atomic ratios of 2b are each subject to a tolerance of plus or minus 40% of the above atomic ratios. include.

[0238] The second metal oxide films 252a and 252b form the insulating film 119, It also functions as a damage mitigation film for the metal oxide film 251a.

[0239] The thickness of the first metal oxide films 251a and 251b is preferably between 3 nm and 200 nm. The wavelength is 3 nm to 100 nm, more preferably 3 nm to 50 nm. The thickness of the metal oxide films 252a and 252b is 3 nm or more and 100 nm or less, preferably 3 The wavelength should be between 50 nm and above.

[0240] The first metal oxide films 251a, 251b and the second metal oxide films 252a, 252b are For example, a non-single crystal structure is also acceptable. A non-single crystal structure is, for example, CAAC-OS(C) as described later. Axis Aligned-Crystalline Oxide Semiconductor This includes uctor, polycrystalline structure, microcrystalline structure (described later), or amorphous structure.

[0241] Furthermore, the first metal oxide films 251a, 251b and the second metal oxide films 252a, 25 In 2b, there are regions with amorphous structures, regions with microcrystalline structures, regions with polycrystalline structures, and CAAC-O A mixed film may be constructed having two or more types of regions: S regions and single-crystal structure regions. For example, the amorphous region, the microcrystalline region, the polycrystalline region, and the CAAC-OS region. In some cases, the monolayer structure may have two or more regions of any single crystal structure. The composite film consists of regions with amorphous structures, regions with microcrystalline structures, regions with polycrystalline structures, and CAAC- It may have a stacked structure consisting of two or more regions, either OS regions or single-crystal structures. .

[0242] Here, a second metal oxide film is placed between the first metal oxide film 251a and the insulating film 119. A 252a is provided. Therefore, between the second metal oxide film 252a and the insulating film 119 In this case, even if carrier traps are formed due to impurities and defects, the carrier trap There is a gap between the region where the layer is formed and the first metal oxide film 251a. As a result, Electrons flowing through the first metal oxide film 251a are less likely to be captured by carrier traps, This makes it possible to increase the on-current of the Zistor 22b and also improve the field-effect mobility. This is possible. Also, when an electron is trapped in a carrier trap, the electron becomes a negative fixed charge and This happens. As a result, the threshold voltage of the transistor fluctuates. However, There is a gap between the first metal oxide film 251a and the region where the carrier trap is formed. Therefore, it is possible to suppress electron capture in carrier traps, and threshold voltage Pressure fluctuations can be reduced.

[0243] Furthermore, the second metal oxide film 252a can shield against 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 251a. Yes. Furthermore, the second metal oxide film 252a is less likely to form oxygen vacancies. For these reasons, It is possible to reduce the impurity concentration and oxygen deficiency in the first metal oxide film 251a. be.

[0244] Furthermore, the first metal oxide films 251a, 251b and the second metal oxide films 252a, 25 2b is not simply stacking the films but creating continuous junctions (in particular the energy at the lower end of the conduction band). The membrane is fabricated so that a structure is formed in which the - changes continuously between each membrane. At the interface, trap centers and recombination centers exist for the first metal oxide films 251a and 251b. Impurities that form defect levels like the mind, or barriers that obstruct carrier flow. The stacked structure is such that there is no such thing. For example, the stacked first metal oxide films 251a, 2 If impurities are present between 51b and the second metal oxide films 252a and 252b, energy The continuity of the energy band is lost, and carriers are trapped or recombined at the interface. It will disappear.

[0245] To form continuous bonding, a multi-chamber type film deposition system equipped with a load lock chamber is required. By using a sputtering device, each film is continuously layered without being exposed to the atmosphere. This is necessary. Each chamber in the sputtering apparatus is inefficient for the metal oxide film. To remove as much pure water as possible, an adsorption-type vacuum pump such as a cryopump is used. Using high vacuum evacuation (5 × 10 -7 Pa~1×10 -4 It is preferable to do so up to approximately Pa. Alternatively, a turbomolecular pump and a cold trap can be combined to run the exhaust system from the chamber. - It is preferable to prevent gases, especially those containing carbon or hydrogen, from flowing back into the container. .

[0246] Furthermore, as shown in Figure 11(B), even if the transistor 22c has a multilayer film 255a That's fine. Alternatively, the multilayer film 255b may be provided as a capacitive electrode.

[0247] The multilayer film 255a consists of a third metal oxide film 253a, a first metal oxide film 251a, and A second metal oxide film 252a is sequentially stacked. Also, a third metal oxide film 253a The first metal oxide film is in contact with the insulating film 106, and the second metal oxide film 252a is in contact with the insulating film 119. The oxide film 251a functions as a channel region.

[0248] The multilayer film 255b consists of a third metal oxide film 253b, a first metal oxide film 251b, and A second metal oxide film 252b is sequentially stacked. Also, a third metal oxide film 253b The first metal oxide film 106 is in contact with the insulating film 106, and the second metal oxide film 252b is in contact with the insulating film 119.

[0249] The third metal oxide films 253a and 153b are formed from the second metal oxide films 252a and 252b. Similar materials and forming methods can be used as appropriate.

[0250] The third metal oxide films 253a and 153b are formed from the first metal oxide films 251a and 251b. A smaller film thickness is preferable. The thickness of the third metal oxide films 253a and 153b should be 1 nm or more. By setting the wavelength to 5nm or less, preferably 1nm to 3nm, the threshold voltage of the transistor is reduced. It is possible to reduce the amount of pressure fluctuation.

[0251] The transistor shown in this embodiment has an insulating film 106 and a first metal oxide film 251a A third metal oxide film 253a is provided in between. Also, the first metal oxide film 251 A second metal oxide film 252a is provided between a and the insulating film 119. Therefore, between the insulating film 106 and the first metal oxide film 251a, and the first metal oxide film 25 Between 1a and the insulating film 119, carrier traps are formed due to impurities and defects. However, between the region where the carrier trap is formed and the first metal oxide film 251a There is a gap. As a result, electrons flowing through the first metal oxide film 251a are carrier-trapped. It is less likely to be captured, and it is possible to increase the on-current of transistor 22c. This can increase field-effect mobility. Also, when electrons are trapped in a carrier trap... As a result, the electron becomes a negative fixed charge. This affects the transistor's threshold voltage. This fluctuates. However, the first metal oxide film 251a and the carrier trap form Because there is a gap between the region where the process takes place, electron trapping in carrier traps is reduced. This makes it possible to reduce fluctuations in the threshold voltage of transistor 22c. .

[0252] Note that the configurations and methods shown in this embodiment may differ from those shown in other embodiments. It can be used in appropriate combinations.

[0253] (Embodiment 5) In this embodiment, the on-current is large, the field effect mobility is high, and the variation in electrical characteristics is Regarding a method for fabricating a small number of transistors and capacitive elements by reducing the number of photomasks, This will be explained using Figures 14 and 15. In this embodiment, the trap shown in Embodiment 2 will be used. This explanation will use a generator and its manufacturing method, but this embodiment may be adapted to other embodiments as appropriate. It can be used. Furthermore, the description of configurations that overlap with Embodiment 2 will be omitted.

[0254] Figure 14 is a top view of pixel 13, and Figure 15(A) shows the dashed lines AB and CD in Figure 14. Figure 15(B) is a cross-sectional view between the points E and F shown by the dashed line in Figure 14.

[0255] Transistor 22d is located in the region where the scan line and signal line intersect. STA 22d consists of a conductive film 103 that functions as a gate electrode, and a gate insulating film (shown in Figure 15). ), a metal oxide film 109a in which a channel region is formed on the gate insulating film, Conductive films 114, 115 and metal oxide film 109 function as source and drain electrodes. a. An insulating film covering the conductive films 114 and 115 (not shown in Figure 15), and a gate electrode It is composed of a functional conductive film 243. The transistor 22d is located at the aperture 241. It is characterized in that conductive films 103 and 243, which function as gate electrodes, are connected. do.

[0256] Next, the cross-sectional structure of transistor 22d will be explained using Figure 15. Figure 15(A Figure 15(B) is a cross-sectional view of transistor 22d in the channel length direction, and Figure 15(B) is a transistor This is a cross-sectional view of channel 22d.

[0257] The transistor 22d shown in Figures 15(A) and 15(B) is a channel etch type transistor. A conductive film 103 which functions as a gate electrode provided on the substrate 101, and An insulating film 105 in contact with the plate 101 and the conductive film 103, and an insulating film 106 in contact with the insulating film 105. And, through insulating films 105 and 106, the metal oxide film 109a overlaps with the conductive film 103, and gold It has conductive films 114 and 115 in contact with the oxide film 109a. In addition, insulating film 105, The insulating film 119 is in contact with the edge film 106, the metal oxide film 109a, and the conductive films 114 and 115. , an insulating film 121 in contact with insulating film 119, and a gate electrode that functions in contact with insulating film 121 It has a conductive film 243. The insulating film 105 and insulating film 106 function as gate insulating films. Furthermore, insulating film 119 and insulating film 121 function as gate insulating films.

[0258] As shown in Figure 15(B), conductive film 103 and conductive film 243 are insulating film 105, insulating film 106, Insulating film 119, and Insulating film 121, in the opening 241, Furthermore, in the channel width direction of the transistor, the edges of the conductive film 243 are metal oxide films. It is located outside the end of 109a. Also, metal acid is transmitted through insulating film 119 and insulating film 121. The side surface of the oxide film 109a faces the conductive film 243. Also, the conductive film 243 has an opening 241 In this configuration, it faces the side surface of the metal oxide film 109a.

[0259] The conductive film 243 was formed using the same materials and manufacturing method as conductive films 123 and 124. This can be achieved. In addition, the opening 241 is formed at the same time as the opening 152. This allows you to use 5 photomasks without increasing the number of photomasks. Transistor 22d can be fabricated using this method.

[0260] In Figure 15(B), the metal oxide film 109 is located in the channel width direction of the transistor. The side of a faces the conductive film 243 which functions as a gate electrode. Therefore, conductive film 103 Furthermore, the electric field of the conductive film 243 affects not only the plane of the metal oxide film 109a but also its sides. As a result, the region in which carriers flow in the metal oxide film 109a is between the insulating film 106 and gold Only at the interface with the metal oxide film 109a, and at the interface between the metal oxide film 109a and the insulating film 119. It does not include the interior of the metal oxide film 109a, and therefore covers a wide area, so the key in the transistor The amount of carriage movement increases. As a result, the on-current of the transistor increases, and the electric field also increases. The effective mobility increases, typically with a field effect mobility of 10 cm. 2 / V·s or more, and furthermore 20cm 2 The value will be greater than or equal to / V·s. Furthermore, the inductance (L) of the transistor should be between 0.5 μm and 6.5 μm. Preferably, the field effect mobility is increased by setting it to greater than 1 μm and less than 6 μm. He is the author.

[0261] Furthermore, at the edges of the metal oxide film 109a processed by etching, etc., Damage causes defects to form, and the area becomes contaminated with impurities. Therefore, One of the conductive film 103 or conductive film 243 that functions as the gate electrode in the transistor. If only the metal oxide film 109a is formed, even if the electric field is intrinsic or substantially intrinsic, The edges of the metal oxide film 109a are activated by the application of stresses such as n This tends to become a n-type region (low resistance region). Also, this n-type region is a conductive film 114, 115 If it is set up linearly between them, the n-type region becomes the carrier path, parasitic channel A loop is formed. As a result, the increase in drain current at the threshold voltage is stepwise. Furthermore, the transistor becomes one whose threshold voltage is negatively shifted. However, Figure As shown in 15(B), it has conductive films 103 and 243 that are at the same potential, and a channel In the width direction, the conductive film 243 faces the side surface of the metal oxide film 109a, thus conducting The electric field of film 243 also affects the side surface of metal oxide film 109a. As a result, metal oxide film 1 The development of parasitic channels in the lateral surface of 09a, or in the end including the lateral surface and its vicinity, is suppressed. As a result, the rise in drain current at the threshold voltage is steep, indicating superior electrical characteristics. It becomes a transistor.

[0262] Furthermore, the presence of conductive films 103 and 243 provides shielding against external electric fields. Because it has a shielding function, it is provided between the substrate 101 and the conductive film 243, and on the conductive film 243. The fixed charge does not affect the metal oxide film 109a. As a result, stress tests (e.g., ge Applying a negative potential to the electrode -GBT (Gate Bias-Temperature) The deterioration of the stress test is suppressed, and the on-voltage at different drain voltages is also suppressed. This can suppress fluctuations in the rise voltage of the current.

[0263] Note that the BT stress test is a type of accelerated test that shows the effects of long-term use. The characteristic changes (i.e., changes over time) of the ZISTA can be evaluated in a short time. In particular, BT S The change in the transistor's threshold voltage before and after the Tress test is used to examine reliability. This is an important indicator. The smaller the fluctuation in threshold voltage before and after the BT stress test, the better. Therefore, it can be said that it is a highly reliable transistor.

[0264] Furthermore, in Figure 15(B), one side of the metal oxide film 109a in the channel width direction. An opening is provided on the side of the conductive film 103 and conductive film 243 are electrically connected at the opening. Although connected, an opening is also provided on the other side, and the conductive film 103 and the conductive film are connected in this opening. The conductive film 243 may be electrically connected. This prevents an increase in the resistance of the conductive film 243. This is possible, and the electric field of the conductive film 243 is transmitted from both sides of the metal oxide film 109a to the metal oxide film 109a. It is possible to influence the physical film 109a, thereby increasing the on-current of the transistor. Furthermore, it is possible to increase the field effect mobility.

[0265] Note that the configurations and methods shown in this embodiment may differ from those shown in other embodiments. It can be used in appropriate combinations.

[0266] (Embodiment 6) Using the transistors and capacitive elements shown in Embodiments 1 to 5, the drive circuit is It can be manufactured.

[0267] Furthermore, the transistor 22d shown in Embodiment 4 has a large on-current and high mobility. Therefore, circuits composed of transistors that need to carry large currents, such as buffers, are not suitable. By using transistor 22d, the channel length and channel width can be reduced. This is possible, and it is possible to reduce the area of ​​the transistor. As a result, the area of ​​the drive circuit The size is reduced. In semiconductor devices having a drive circuit in the peripheral part, typically in display devices, the drive By reducing the area of ​​the dynamic circuit, the area of ​​the pixel portion in the display device can be increased. In other words, it is possible to narrow the bezel of the display device.

[0268] Note that the configurations and methods shown in this embodiment may differ from those shown in other embodiments. It can be used in appropriate combinations.

[0269] (Embodiment 7) In this embodiment, a display module to which a semiconductor device according to one aspect of the present invention is applied is described below. We will explain using Figure 16.

[0270] The display module 8000 shown in Figure 16 consists of an upper cover 8001 and a lower cover 8002. In between, the touch panel 8004 connected to the FPC8003 and the FPC8005 are connected. Display panel 8006, backlight unit 8007, frame 8009, printed circuit board It has a board 8010 and a battery 8011. It also has a backlight unit 8007 and a battery. Features such as the Terry 8011 and Touch Panel 8004 may not be available.

[0271] A semiconductor device according to one aspect of the present invention can be used, for example, as a display panel 8006.

[0272] The upper cover 8001 and the lower cover 8002 are the touch panel 8004 and the display panel. The shape and dimensions can be appropriately modified to match the size of the 8006.

[0273] The touch panel 8004 is a display panel using either a resistive or capacitive touch panel. It can be used superimposed on 8006. Also, the opposing substrate (sealing substrate) of the display panel 8006 It is also possible to incorporate touch panel functionality into the board. Alternatively, a display panel It is also possible to incorporate an optical sensor within each of the 8006 pixels to create an optical touch panel. Alternatively, an electrode for a touch sensor can be provided within each pixel of the display panel 8006, and a capacitive touch sensor can be used. It can also be used as a touch panel.

[0274] The backlight unit 8007 has a light source 8008. A configuration using a light-diffusing plate may be provided at the end of the unit 8007.

[0275] Frame 8009 provides protection for the display panel 8006, as well as the movement of the printed circuit board 8010. It has the function of an electromagnetic shield to block electromagnetic waves generated by the operation. The 8009 may also function as a heat sink.

[0276] The printed circuit board 8010 contains power supply circuits and signals for outputting video and clock signals. It has a power processing circuit. The power supply that provides power to the power supply circuit is an external commercial power supply. Alternatively, a separate power source, battery 8011, may also be used. Item 1 can be omitted when using commercial power.

[0277] Furthermore, the display module 8000 includes components such as polarizing plates, phase difference plates, and prism sheets. You may add more.

[0278] The configuration shown in this embodiment may be used in appropriate combination with the configurations shown in other embodiments. It is possible.

[0279] (Embodiment 8) In this embodiment, as an example of a semiconductor device, the semiconductor device described in the above embodiment is used. This section describes the electronic devices that can be installed.

[0280] As an electronic device, for example, a television system (also known as a television or television receiver) (e.g., 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 personal digital assistants, audio playback devices, and large game machines such as pachinko machines. A specific example of electronic equipment is shown in Figure 12.

[0281] Figure 12(A) shows an example of a television system. The television system 7100 is The display unit 7103 is incorporated into the housing 7101. The display unit 7103 displays images. It is possible to display the device described in the above embodiment and use the display unit 7103. This is possible. In addition, here we have a configuration in which the housing 7101 is supported by the stand 7105. It is showing.

[0282] The television unit 7100 is operated using the control switches on the housing 7101, or a separate unit. This can be done using the remote controller 7110. The control keys 7109 allow you to operate the channel and volume, and the display unit 71 The video displayed on 03 can be controlled. Additionally, the remote controller 7110 can be used to control the video. The configuration includes a display unit 7107 that displays information output from the remote controller. You may do so.

[0283] The television system 7100 will consist of a receiver, modem, and other components. This allows for the reception of regular television broadcasts, and furthermore, wired or wireless connections are available via the modem. By connecting to a communication network, one-way (sender to receiver) or two-way communication is possible. It is also possible to perform two-way information communication (between a sender and receiver, or between receivers, etc.). .

[0284] Figure 12(B) shows a computer, consisting of a main unit 7201, a casing 7202, a display unit 7203, Includes keyboard 7204, external connection port 7205, pointing device 7206, etc. The computer uses the display device described in the above embodiment as the display unit 7203. It is possible.

[0285] Figure 12(C) shows a portable gaming machine, consisting of two cabinets, cabinet 7301 and cabinet 7302. It is connected by a connecting part 7303 so that it can be opened and closed. The housing 7301 has a display The unit 7304 is incorporated, and the display unit 7305 is incorporated into the housing 7302. Also, The portable gaming machine shown in Figure 12(C) also includes a speaker unit 7306 and 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, rotational speed, distance, light, liquid, magnetism, temperature) , chemical substances, sound, time, hardness, electric field, electric current, voltage, power, radiation, flow rate, humidity, gradient, (Including functions for measuring vibration, odor, or infrared radiation), microphones (7312), etc. It is equipped with. Of course, the configuration of portable gaming machines is not limited to those described above, and at least displays Both or one of section 7304 and display section 7305 are equipped with the display device described in the above embodiment. It is sufficient to use a fixed structure, and other auxiliary equipment can be provided as appropriate. Figure 1 The portable gaming machine shown in 2(C) reads the program or data recorded on the recording medium. Features include the ability to display information on the screen and to share information wirelessly with other portable gaming machines. It has the function of [the device]. However, the functions of the portable gaming machine shown in Figure 12(C) are not limited to this. It can have various functions.

[0286] Figure 12(D) shows an example of a mobile phone. The mobile phone 7400 has a housing 740 In addition to the display unit 7402 incorporated into 1, there are also operation buttons 7403, an external connection port 7404, It is equipped with speaker 7405, microphone 7406, etc. Note that mobile phone 7400 is above This is manufactured by using the display device described in the above embodiment as the display unit 7402.

[0287] The mobile phone 7400 shown in Figure 12(D) allows the user to touch the display unit 7402 with their finger or the like. You can input information. You can also perform operations such as making phone calls or composing emails. This can be done by touching the display unit 7402 with a finger or the like.

[0288] The display unit 7402 has three main modes. The first is primarily for displaying images. The first is the display mode, the second is the input mode which is mainly for inputting information such as characters. The third is the display mode. This is a display + input mode, which is a combination of two modes: display mode and input mode.

[0289] For example, when making a phone call or composing an email, the display unit 7402 is used for text input. The primary text input mode is set to [this mode], and you should perform the input operation for the characters displayed on the screen. In addition, it is possible to display a keyboard or number buttons on most of the screen of the display unit 7402. preferable.

[0290] Furthermore, the 7400 mobile phone contains sensors that detect tilt, such as a gyroscope and an accelerometer. By providing a detection device having the following, the orientation (vertical or horizontal) of the mobile phone 7400 can be determined, The display on the display unit 7402 can be configured to switch screen displays automatically.

[0291] Furthermore, the screen mode can be switched by touching the display unit 7402 or the housing 7401. This is performed by operating the operation button 7403. Also, the type of image displayed on the display unit 7402 It is also possible to switch between them depending on the type. For example, if the image signal displayed on the display unit is moving Switch to display mode if the data is an image, and to input mode if the data is text.

[0292] Furthermore, in input mode, the signal detected by the optical sensor of the display unit 7402 is detected, and the display If there is no input via touch operation on the display unit 7402 for a certain period of time, the screen mode will be changed to input mode. You may also control the system to switch from the "Do" display mode to the "Display Mode".

[0293] The display unit 7402 can also function as an image sensor. For example, the display unit 7 By touching device 402 with the palm or fingers, the user can be authenticated by capturing images of their palm print, fingerprints, etc. Furthermore, the display unit may have a backlight that emits near-infrared light or a sensing element that emits near-infrared light. By using a light source, it is also possible to image finger veins, palmar veins, and other veins.

[0294] Figure 12(E) shows an example of a foldable computer. Computer 7450 connects chassis 7451L and chassis 7451R via hinge 7454. It is equipped with the following: control button 7453, left speaker 7455L and right speaker 7 In addition to the 455R, there is an external connection port 745 on the side of the computer 7450, which is not shown in the illustration. It is equipped with 6. Furthermore, the display unit 7452L is provided in the housing 7451L, and the housing 7451R is When the hinge 7454 is folded so that the provided display units 7452R face each other, the display The part can be protected by the enclosure.

[0295] Display units 7452L and 7452R not only display images, but also provide information when touched with a finger or other object. You can input data. For example, you can select an installed program by touching its icon with your finger. You can launch the program. Alternatively, change the distance between the fingers touching two points on the displayed image. You can zoom in or out of the image. Or, you can move your finger that is touching a part of the displayed image. Images can be moved. Additionally, a keyboard image can be displayed, allowing you to touch the displayed characters and symbols with your finger. You can also select and enter information.

[0296] Furthermore, the computer 7450 is equipped with a gyroscope, accelerometer, and GPS (Global Power). (Operation System) Equipped with a receiver, fingerprint sensor, and video camera. It can also be done. For example, a detection device having a sensor that detects tilt, such as a gyroscope or accelerometer. By providing a space, the orientation of the computer 7450 (vertical or horizontal) is determined, and the screen to be displayed is determined accordingly. It can be configured to automatically switch orientations.

[0297] Furthermore, the computer 7450 can connect to a network. In addition to displaying information on the internet, it can also remotely access other electronic devices connected to the network. It can be used as a terminal for operation.

[0298] Note that the configurations and methods shown in this embodiment may differ from those shown in other embodiments. It can be used in appropriate combinations. [Examples]

[0299] In this example, the lateral diffusion length of the conductive region in the metal oxide film was investigated. Ta.

[0300] First, I will explain the structure of the sample.

[0301] Figure 18(A) shows a top view of the sample, and Figure 1 shows a cross-sectional view corresponding to A and B in Figure 18(A). This is shown in 8(B).

[0302] The sample consists of a substrate 301, an insulating film 303 on the substrate 301, and a metal oxide on the insulating film 303. The film 305, a pair of conductive films 307 and 308 in contact with a part of the metal oxide film 305, and a metal acid An insulating film 309 that is in contact with a portion of the oxide film 305 and a pair of conductive films 307 and 308, Insulating film 303, metal oxide film 305, pair of conductive films 307, 308, and insulating film 309 It has a contact insulating film 311. The insulating film 309 has openings 310a and 310b. Furthermore, the insulating film 311 has a metal oxide film 305 at the openings 310a and 310b. To come into contact with.

[0303] In this case, a glass substrate was used as substrate 301.

[0304] Furthermore, the insulating film 303 consists of a first silicon nitride film with a thickness of 50 nm and a film with a thickness of 300 nm A second silicon nitride film, a third silicon nitride film with a thickness of 50 nm, and an acid with a thickness of 50 nm. A laminated film was used, in which silicon nitride films were stacked in sequence.

[0305] Furthermore, as the metal oxide film 305, an In-Ga-Zn oxide film with a thickness of 35 nm was used. Note that the In-Ga-Zn oxide film is In-Ga-Zn with an In:Ga:Zn ratio of 1:1:1. It was formed by sputtering using an N-oxide target.

[0306] Furthermore, the pair of conductive films 307 and 308 consist of a first titanium film with a thickness of 50 nm and a 4 A laminated film consisting of a 00nm aluminum film and a second 100nm thick titanium film stacked in sequence. I used it.

[0307] Furthermore, a silicon oxidizride film with a thickness of 450 nm was used as the insulating film 309.

[0308] Furthermore, a silicon nitride film with a thickness of 100 nm was used as the insulating film 311.

[0309] The metal oxide film 305 is in the openings 310a and 310b of the insulating film 309, It is in contact with 11. Therefore, the metal oxide film 305 has a region 305a that is in contact with the insulating film 309. It has regions 305b and 305c that are in contact with the insulating film 311. The insulating film 311 is nitrogen Because it is formed of a silicon film, regions 305b and 305c are different from region 305a. And it has high conductivity.

[0310] Hydrogen contained in the insulating film 311 diffuses laterally in the metal oxide film 305. The region where it has diffused has high conductivity. Therefore, the width of the insulating film 309, i.e., the opening 310a If the spacing d of 310b becomes narrower, the conductivity will also increase in region 305a. Even when in contact with the insulating film 309, it ceases to function as the channel region of the transistor.

[0311] Therefore, the width of the insulating film 309, i.e., the distance d between the openings 310a and 310b, was set to various values. The sample was prepared. Next, the potential difference between the pair of conductive films 307 and 308 was set to 0.99V. A voltage was applied, and the overall resistance of the metal oxide film 305 was measured.

[0312] Table 1 and Figure 19 show the spacing d between the openings 310a and 310b and the resistance of the metal oxide film 305. The values ​​are shown. Two samples were prepared as comparative examples. Comparative Example 1 involves opening the insulating film 309. Samples that do not have openings 310a and 310b, i.e., all of the metal oxide film 305 is silicon oxide nitride This is a sample that comes into contact with the insulating film 309 formed by the film. Comparative Example 2 is a sample that does not have the insulating film 309. In a sample where none exists, that is, the insulating film 311 is formed entirely of a silicon nitride film, and It is the sample that comes into contact with the sample.

[0313] [Table 1]

[0314] From Table 1 and Figure 19, if the spacing d between openings 310a and 310b exceeds 3 μm, metal oxidation occurs. As the resistance of the material film 305 increases, the highly conductive region of the metal oxide film 305 The lateral diffusion length of regions 305b and 305c is estimated to be approximately 1.5 to 2 μm on each side. It can be done.

[0315] Therefore, the channel region of the transistor and the electrodes of the capacitive element are formed into a single metal oxide film. In this case, the distance between the channel region of the transistor and the electrodes of the capacitive element is set to 1.5 μm. By making it larger, even larger than 2 μm, and even larger than 3 μm, excellent switch A transistor with chapping characteristics and the electrodes of a highly conductive capacitive element are connected in one metal oxide It can be formed as a physical film.

Claims

1. Having a first pixel and a second pixel adjacent in a first direction, and first to third conductive layers, Each of the first pixel and the second pixel is, A semiconductor layer having a channel formation region for transistors, A fourth conductive layer electrically connected to the semiconductor layer, A pixel electrode electrically connected to the semiconductor layer via the aforementioned fourth conductive layer, The film comprises a metal oxide film having a region that overlaps with the pixel electrode, The metal oxide film in the first pixel is electrically connected to the metal oxide film in the second pixel via the first to third conductive layers. Each of the first conductive layer and the third conductive layer has the same material as the fourth conductive layer. The second conductive layer has the same material as the pixel electrode, In a plan view, the second conductive layer has a region that extends in the first direction and has a region that overlaps with the metal oxide film of the first pixel and a region that overlaps with the metal oxide film of the second pixel. In a plan view, the length of the first conductive layer in the second direction is smaller than the length of the second conductive layer in the second direction. The second direction is a direction that intersects the first direction, The semiconductor layer has a region in which carriers flow in the second direction, A display device in which a capacitive element is formed in the region where the pixel electrode and the metal oxide film overlap in each of the first and second pixels.

2. Having a first pixel and a second pixel adjacent in a first direction, and first to third conductive layers, Each of the first pixel and the second pixel is, A semiconductor layer having a channel formation region for transistors, A fourth conductive layer electrically connected to the semiconductor layer, A pixel electrode electrically connected to the semiconductor layer via the aforementioned fourth conductive layer, The film comprises a metal oxide film having a region that overlaps with the pixel electrode, The metal oxide film in the first pixel is electrically connected to the metal oxide film in the second pixel via the first to third conductive layers. Each of the first conductive layer and the third conductive layer has the same material as the fourth conductive layer. The second conductive layer has the same material as the pixel electrode, In a plan view, the second conductive layer has a region that extends in the first direction and has a region that overlaps with the metal oxide film of the first pixel and a region that overlaps with the metal oxide film of the second pixel. In a plan view, the length of the first conductive layer in the second direction is smaller than the length of the second conductive layer in the second direction. The second direction is a direction that intersects the first direction, The semiconductor layer has a region in which carriers flow in the second direction, Each of the first conductive layer and the second conductive layer does not have a region that overlaps with the pixel electrode of the first pixel, and does not have a region that overlaps with the pixel electrode of the second pixel. A display device in which a capacitive element is formed in the region where the pixel electrode and the metal oxide film overlap in each of the first and second pixels.

Images