Indication device

Abstract

To provide a liquid crystal display device in which power consumption is reduced, and provide a liquid crystal display device in which change in transmittance is reduced.SOLUTION: The liquid crystal display device includes a first substrate, a second substrate, and a liquid crystal layer held between the first substrate and the second substrate. The first substrate includes: a transistor including an oxide semiconductor film in a channel formation region; a pixel electrode electrically connected to the transistor; an insulating layer in contact with the pixel electrode; and a first common electrode in contact with the insulating layer. The second substrate faces the first substrate and includes a second common electrode. A negative liquid crystal material is used for the liquid crystal layer. A specific resistivity of the liquid crystal material is greater than or equal to 1.0×1013 Ω cm or more and 1.0×1016 Ω cm or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates, for example, to semiconductor devices, display devices, light-emitting devices, methods for driving them, or the This invention relates to methods for manufacturing these. In particular, the present invention relates to, for example, active matrix type liquid crystal displays. Regarding the device. [Background technology]

[0002] In recent years, with the rapid spread of mobile information terminals such as smartphones, the performance of the terminals themselves has increased. Technology is also progressing rapidly. Screens are getting larger and higher resolution, and the improvement in screen resolution and In addition, the power consumption of display devices is becoming increasingly important. Examples of display devices include liquid crystal displays (LCDs). A typical example is a liquid crystal display device that uses a component.

[0003] As a display method for liquid crystal displays, for example, liquid crystal molecules having negative dielectric anisotropy are used as a substrate. Vertical orientation (VA) mode, which is oriented perpendicular to the surface, and modes with positive or negative dielectric anisotropy. An in-plane switch that applies a transverse electric field to the liquid crystal layer by orienting liquid crystal molecules horizontally with respect to the substrate surface. Examples include IPS (Intensity-Based Switching) mode and FFX (Flash-Flash Switching) mode.

[0004] For example, as a liquid crystal display device using the FFS drive method described above, having a first common electrode layer A liquid crystal sandwiched between substrate 1, substrate 1 and substrate 2, and high-speed input data transfer In order to provide high-speed response to speed and a wide viewing angle for the viewer, the first substrate is The first common electrode layer and both the pixel electrode and the second common electrode layer on the second substrate A display device having high-speed response and a wide viewing angle is disclosed, which includes means for generating an electric field in between. (See Patent Document 1)

[0005] Further, as a liquid crystal display device of the FFS driving method, there has been disclosed a liquid crystal display device capable of high-speed response by driving liquid crystals using two pairs of electrodes (see Patent Document 2). PRIOR ART DOCUMENTS PATENT DOCUMENTS

[0006] Patent Document 1 Japanese National Publication of International Patent Application No. 2006-523850 Patent Document 2 International Publication No. 2013 / 001979 Pamphlet SUMMARY OF THE INVENTION PROBLEM TO BE SOLVED BY THE INVENTION

[0007] In the liquid crystal driving device disclosed in Patent Document 1, liquid crystal molecules are controlled using three electrodes to achieve wide viewing angle and high-speed response. However, even if high-speed response can be achieved, the three electrodes need to be driven separately, which results in an increase in power consumption of the display device.

[0008] Further, in the liquid crystal driving device disclosed in Patent Document 2, it is necessary to drive the liquid crystal with two pairs of electrodes, in other words four electrodes, so at least four power supply lines are required, which brings about a problem that the number of power supply lines increases. Further, along with the increase in the number of power supply lines, the driving method or control method for the voltage applied to the liquid crystal becomes complicated, and there is also a problem that power consumption increases along with the increase in the number of power supply lines.

[0009] Against the technical background described above, one object of an aspect of the present invention is to provide a liquid crystal display device that can achieve reduction in power consumption. Alternatively, an aspect of the present invention is to One of the challenges is to provide a liquid crystal display device that can reduce fluctuations in transmittance. Alternatively, one aspect of the present invention relates to a liquid crystal display that can reduce fluctuations in display brightness. One of the objectives of this invention is to provide a display device. Alternatively, one aspect of this invention relates to display flickering. One of the objectives is to provide a liquid crystal display device that can achieve a reduction in [unclear]. One aspect of the present invention provides a liquid crystal display device that can achieve eye-friendly display. One of the challenges is to reduce the impact on eye fatigue. Alternatively, one aspect of the present invention aims to reduce the impact on eye fatigue. One of the objectives is to provide a liquid crystal display device that can display the following:

[0010] Furthermore, the description of these problems does not preclude the existence of other problems. One approach does not require that all of these issues be resolved. The title will become clear from the description in the specification, drawings, claims, etc. It is possible to extract other issues from the descriptions in the drawings, claims, etc. [Means for solving the problem]

[0011] In a liquid crystal display device according to one aspect of the present invention, after the writing of the image signal to the pixel portion is stopped, In addition, to maintain the display of the image in the pixel area, an insulated gate electrode with an extremely low off-current is required. A field-effect transistor (hereinafter simply referred to as a transistor) is provided in the pixel. The inverter is used as an element to control the voltage supply to the liquid crystal elements of the pixels. This ensures a longer period during which voltage is supplied to the liquid crystal elements. Therefore, Like a still image, the pixel portion contains the same image information over several consecutive frame periods. When an image signal is repeatedly written, the writing of the image signal to the pixel area is temporarily stopped. By stopping, the drive frequency is lowered, in other words, the image signal within a certain period of time. The image display can be maintained even with a reduced number of write cycles.

[0012] Furthermore, in a liquid crystal display device according to one aspect of the present invention, the liquid crystal elements are pixel electrodes, and the first common electrode It has a liquid crystal layer to which an electric field is applied by three electrodes: the pole and the second common electrode. The liquid crystal layer uses a negative-type liquid crystal material, and the resistivity of the liquid crystal material is 1.0 × 10⁻⁶. 13 Ω·c m or more 1.0×10 16 It is less than Ω·cm. By using this configuration, a certain Even if the number of image signal writes within the period is reduced, the transmittance fluctuation is small, and the liquid crystal surface For the viewer of the display device, it can be a liquid crystal display device with suppressed image flicker. . [Effects of the Invention]

[0013] According to one aspect of the present invention, a liquid crystal display device is provided that can achieve a reduction in power consumption. Furthermore, according to one aspect of the present invention, it is possible to reduce fluctuations in transmittance. We can provide a liquid crystal display device that can do this. [Brief explanation of the drawing]

[0014] [Figure 1] A circuit diagram and a cross-sectional view illustrating the pixel configuration of a liquid crystal display device according to one embodiment of the present invention. [Figure 2] A diagram illustrating the transmittance due to polarity when using positive-type and negative-type liquid crystal materials. [Figure 3] A block diagram illustrating an example of the panel configuration of a liquid crystal display device according to one embodiment of the present invention. [Figure 4]A block diagram illustrating the configuration of a liquid crystal display device according to one embodiment of the present invention. [Figure 5] A top view illustrating a pixel of a liquid crystal display device according to one embodiment of the present invention. [Figure 6] A cross-sectional view illustrating a pixel of a liquid crystal display device according to one embodiment of the present invention. [Figure 7] A cross-sectional view illustrating a method for manufacturing pixels in a liquid crystal display device according to one embodiment of the present invention. [Figure 8] A cross-sectional view illustrating a method for manufacturing pixels in a liquid crystal display device according to one embodiment of the present invention. [Figure 9] A cross-sectional view of a transistor and a diagram illustrating the energy bands of an oxide semiconductor, which can be used in a liquid crystal display device according to one embodiment of the present invention. [Figure 10] A top view illustrating a pixel of a liquid crystal display device according to one embodiment of the present invention. [Figure 11] A cross-sectional view illustrating a pixel of a liquid crystal display device according to one embodiment of the present invention. [Figure 12] A cross-sectional view illustrating a method for manufacturing pixels in a liquid crystal display device according to one embodiment of the present invention. [Figure 13] A cross-sectional view illustrating a method for manufacturing pixels in a liquid crystal display device according to one embodiment of the present invention. [Figure 14] A diagram illustrating an electronic device that can use a liquid crystal display device according to one embodiment of the present invention. [Figure 15] A cross-sectional view illustrating the sample structure of the example. [Figure 16] A diagram illustrating the transmittance of the sample in the example. [Figure 17] A diagram illustrating the transmittance of the sample in the example. [Figure 18] A diagram illustrating the transmittance of the sample in the example. [Figure 19] A diagram illustrating the transmittance of the sample in the example. [Figure 20] A diagram illustrating the transmittance of the sample in the example. [Figure 21] A diagram illustrating the transmittance of the sample in the example. [Figure 22] A cross-sectional view illustrating the configuration of the liquid crystal display used in the calculations of the example. [Figure 23]A diagram illustrating the calculation results of the transmittance in the example. [Modes for carrying out the invention]

[0015] 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. It will be easily understood by those skilled in the art that various details can be changed. The Specification shall not be interpreted as being limited to the descriptions of the embodiments shown below.

[0016] In this specification, a liquid crystal display device refers to a panel in which liquid crystal elements are formed in each pixel, A module in which an IC, including a drive circuit or controller, is mounted on the panel. This includes the above. Furthermore, a liquid crystal display device according to one aspect of the present invention is said liquid crystal display device The term "element substrate" refers to a substrate that represents a form of liquid crystal element before it is completed, during the process of manufacturing the element. Include in the category.

[0017] Furthermore, a liquid crystal display device according to one aspect of the present invention includes a finger or stylus that points to the liquid crystal display device. A position input device that can detect a position and generate a signal containing that position information. Chipanel may be included as a component.

[0018] (Embodiment 1) In this embodiment, an example of the pixel configuration of a liquid crystal display device according to one aspect of the present invention is shown in Figure We will use 1 to explain.

[0019] <Example of pixel configuration> Figure 1(A) shows an example of the pixel configuration of a liquid crystal display device according to one aspect of the present invention. The pixel 100 shown in the image is connected to the liquid crystal element 111 and controls the supply of image signals to the liquid crystal element 111. It has a transistor 112 and a capacitive element 113.

[0020] The liquid crystal element 111 includes a pixel electrode, a first common electrode, a second common electrode, and a pixel electrode, A liquid crystal layer containing a liquid crystal material to which a voltage is applied between one common electrode and a second common electrode, It has.

[0021] Furthermore, in Figure 1(A), the liquid crystal element 111 has a voltage between the pixel electrode and the first common electrode. The region to which the voltage is applied is defined as the liquid crystal element 111a, and the voltage is applied between the pixel electrode and the second common electrode. The region to be treated is the liquid crystal element 111b, and a voltage is applied between the first common electrode and the second common electrode. The regions to which the current is applied are shown as liquid crystal elements 111c, and each is illustrated accordingly.

[0022] Furthermore, in Figure 1(A), the liquid crystal element 111 is FFS (Fringe Field Switch). This example illustrates the case where the mode is tching, and the pixel electrode and the first common electrode are insulating films. It has an overlapping region with the pixel electrode and the first common electrode. Voltage V LC It functions as a capacity for holding. In Figure 1(A), the region The capacitance of this element is shown as capacitive element 113 in the diagram.

[0023] Transistor 112 controls the potential of the image signal input to wiring SL, which is used to control the image of liquid crystal element 111. It controls whether or not to apply power to the elemental electrode. The first common electrode of the liquid crystal element 111 is supplied with a predetermined reference power. Place V COM1 It is given.

[0024] The following describes the specific connections between the liquid crystal element 111, the transistor 112, and the capacitive element 113. Let me explain the relationship.

[0025] In this specification, "connection" refers to an electrical connection, including current, voltage, or potential. However, this corresponds to a state where it can be supplied or transmitted. Therefore, a connected state is directly This does not necessarily mean that a connection is established, but rather that current, voltage, or potential is available, or To enable transmission, circuit elements such as wiring, resistors, diodes, and transistors are used. This category also includes situations where the devices are indirectly connected.

[0026] Furthermore, even if components that appear independent on the circuit diagram are connected to each other, in reality In some cases, for example, when a part of the wiring functions as an electrode, one conductive film can function as multiple components. It may also have the functions of a single conductive device. In this specification, connection means such a single conductive device. This category also includes cases where a membrane possesses the functions of multiple components.

[0027] Furthermore, the source and drain of a transistor are the channel type and each terminal of the transistor. The name changes depending on the level of the potential supplied to the child. Generally, n-channel type In a transistor, the terminal to which a low potential is applied is called the source, and the terminal to which a high potential is applied is called the source. The terminal is called the drain. Also, in a p-channel transistor, a low potential is applied. The terminal to which a high potential is applied is called the drain, and the terminal to which a high potential is applied is called the source. For convenience, assuming that the source and drain are fixed, the transistor connections are... Sometimes the relationship is explained, but in reality, the source and drain are named according to the potential relationship described above. The roles are reversed.

[0028] Furthermore, the source of a transistor is a part of the semiconductor film that functions as the active layer. This refers to a region, or a source electrode connected to the semiconductor film mentioned above. Similarly, the transistor A drain is a drain region which is part of the semiconductor film, or a drain which is connected to the semiconductor film. The term "gate" refers to the drain electrode. Similarly, "gate" refers to the gate electrode.

[0029] In the pixel 100 shown in Figure 1(A), the gate of transistor 112 is electrically connected to the wiring GL. They are connected. One of the source and drain of transistor 112 is connected to wiring SL. The source and drain of transistor 112 are in contact with the pixel electrode of liquid crystal element 111. It continues. The capacitive element 113 has a pair of electrodes, and one of the electrodes is made of liquid crystal. It is electrically connected to the pixel electrode of sub-element 111, and the other electrode has a predetermined potential V COM1 but It is given. Also, in the pixel 100 shown in Figure 1(A), the second common electrode of the liquid crystal element 111 It is connected to wiring CL, and wiring CL has V COM2 It is given

[0030] In Figure 1(A), at pixel 100, a switch controls the input of the image signal to pixel 100. As an example, the case where one transistor 112 is used is shown. However, pixel 10 In case 0, multiple transistors may be used to function as a single switch.

[0031] Furthermore, in one aspect of the present invention, the off-current of transistor 112 is made extremely small. The above configuration ensures that the period during which the voltage applied to the liquid crystal element 111 is maintained is extended. Therefore, like a still image, the image can be displayed over several consecutive frames. When an image signal containing the same image information is written to element 100, the drive frequency is lowered. In other words, reduce the number of times the image signal is written to pixel 100 within a certain period. Even if this is done, the display of gradation can be maintained. For example, a highly purified oxide semiconductor By using transistor 112 included in the channel formation region, the interval for writing the image signal can be adjusted. It can be 10 seconds or more, preferably 30 seconds or more, and even more preferably 1 minute or more. Therefore, the longer the interval at which the image signal is written, the more power consumption can be reduced. It is possible.

[0032] Transistor 112 has a larger band gap than silicon or germanium. By using semiconductors such as oxide semiconductors with low intrinsic carrier density, transistor 112 This increases the voltage resistance and significantly reduces the off-current. Therefore, it is possible to use ordinary silicon and Compared to using transistors made of semiconductors such as germanium, the transistor This prevents degradation of the TA 112 and maintains the voltage held in the liquid crystal element 111.

[0033] Furthermore, even if the amount of charge leaking through transistor 112 is small, several factors can contribute to this. Furthermore, the electric field applied to the liquid crystal layer may change after the image signal writing is complete.

[0034] For example, one factor that changes the electric field applied to the liquid crystal layer is ionic impurities in the alignment layer. Adsorption is one example. Liquid crystal materials contain ionic impurities, and these impurities are oriented When adsorbed onto a film, an electric field called residual DC may be generated. This is caused by the adsorption of impurities. When residual DC is generated, the electric field applied to the liquid crystal layer changes, thus affecting the transmittance of the liquid crystal element 111. This also changes. And the longer the DC voltage is applied to the liquid crystal element, the greater the residual DC. becomes stronger, so in a driving method with a long image signal writing interval as in one aspect of the present invention, the change in transmittance is larger than that in a normal driving method with a frame frequency of approximately 60 Hz and is likely to occur.

[0035] Another factor that causes a change in the electric field applied to the liquid crystal layer is leakage current flowing through the liquid crystal element 111. When a voltage is applied to the liquid crystal element 111, between the pixel electrode and the first common electrode through the liquid crystal layer, or between the pixel electrode and the second common electrode through the liquid crystal layer, a slight leakage current flows. Therefore, as time passes, the voltage applied to the liquid crystal element 111 has a decreased absolute value. Accordingly, as in one aspect of the present invention, the writing interval of image signals is long in the case of such a driving method, for example, compared with a normal driving method having a frame frequency of approximately 60 Hz, the change in transmittance is likely to become large.

[0036] However, in the liquid crystal display device according to one aspect of the present invention, the liquid crystal layer used for the liquid crystal element 111 uses a negative-type liquid crystal material, and the specific resistivity of the liquid crystal material is 1.0×10 13 Ω·cm or more and 1. 0×10 16 Ω·cm or less. More preferably, the specific resistivity of the liquid crystal material is 1.0 ×10 14 Ω·cm or more and 1.0×10 16 Ω·cm or less. Note that the value of the specific resistivity of the liquid crystal material in this specification and the like is a value measured at 20°C.

[0037] By using a negative-type liquid crystal material for the liquid crystal layer used in the liquid crystal element 111, the liquid crystal element 1 11 can suppress variation in transmittance. In addition, by setting the specific resistivity of the liquid crystal material within the above range , the leakage current flowing through the liquid crystal element 111 can be reduced.

[0038] The liquid crystal element 111 has a polarity applied to the liquid crystal layer (positive (+) polarity or negative (-) polarity). This results in a difference in transmittance. For example, as the material of the liquid crystal layer of the liquid crystal element 111, When using di-type and negative-type liquid crystal materials, a difference in transmittance occurs due to polarity. Here, the transmittance due to polarity when using positive-type liquid crystal material and negative-type liquid crystal material. This will be explained using Figure 2. Note that positive-type liquid crystal materials are liquid crystals with positive dielectric anisotropy. A crystalline material is a liquid crystal material, and a negative-type liquid crystal material is a liquid crystal material that possesses negative dielectric anisotropy.

[0039] Figure 2(A) shows the case using a positive-type liquid crystal material (Merck KGaA: MLC-7030). Figure 2(B) shows the voltage-transmittance characteristics of a negative-type liquid crystal material (Merck KGaA: MLC). The voltage-transmittance characteristics when using -3006) are shown separately. Also, Figure 2(A The physical properties of the positive-type liquid crystal material shown are that the dielectric anisotropy Δε is 3.8, and The resistivity ρ is 4.9 × 10⁻⁶ 14 It is Ω·cm. Also, the negative type liquid crystal material shown in Figure 2(B) The material properties are that the dielectric anisotropy Δε is -3.0 and the resistivity ρ is 1.8 × 10⁻⁶. 13 It is Ω·cm. Note that in the voltage-transmittance characteristics shown in Figures 2(A) and (B), the horizontal axis The vertical axis represents voltage (V), and the vertical axis represents transmittance (%). Also, Figure 2(A), (B In the voltage-transmittance characteristics shown, the solid line represents the transmittance when a positive (+) polarity is applied. The dashed lines represent the transmittance when a negative (-) polarity is applied.

[0040] From Figures 2(A) and (B), when using a negative-type liquid crystal material, the liquid crystal layer is applied It can be seen that the difference in transmittance due to polarity is small. This is due to the flexoelectric effect. This is thought to be the cause. The flexoelectric effect is mainly due to molecular shape and orientation distortion. This is a phenomenon in which polarization occurs due to light.

[0041] For example, spontaneous polarization can be achieved by applying orientation distortions such as splay or bend to a nematic liquid crystal. It occurs. Originally, liquid crystal molecules themselves do not distinguish between the polarity of the applied voltage, but spontaneously Polarization tends to exhibit opposite behavior depending on the polarity of the electric field. Therefore, the transmittance variation due to polarity is It is thought that this will occur. The flexoelectric effect will cause flexoelectric The polarization P is expressed by the following formula (1).

[0042]

number

[0043] Here, e is the flexo coefficient mainly due to the molecular shape, and n is the liquid crystal director. The poles are expressed as the product of the flexor coefficient and the orientation strain.

[0044] Therefore, in order to suppress polarization and reduce flicker, the flexor coefficient or orientation may be necessary. Minimizing distortion is preferable.

[0045] As shown in Figures 2(A) and (B), by using a negative-type liquid crystal material, the above-mentioned flexo This can reduce orientation distortion caused by electric effects.

[0046] Furthermore, a liquid crystal display device according to one aspect of the present invention includes a pixel electrode, a first common electrode, and a second common The driving of the liquid crystal element 111 is controlled using electrodes. As shown in the figure, The following explanation will be given using 1(B).

[0047] Figure 1(B) is a cross-sectional view showing an example of a liquid crystal element 111 of a liquid crystal display device according to one embodiment of the present invention. It corresponds to.

[0048] The liquid crystal element 111 has a first common electrode 122 on the substrate 120 and on the first common electrode 122 The insulating layer 124, the pixel electrode 126 on the insulating layer 124, and the insulating layer 124 and the pixel electrode 12 6 The liquid crystal layer 134 on top, the second common electrode 132 on the liquid crystal layer 134, and the second common electrode 13 It has a substrate 130 on 2. Also, as shown in Figure 1(B), the pixel electrode 126 is insulated The insulating layer 124 is in contact with the first common electrode 122. The conductive electrode 122, insulating layer 124, and pixel electrode 126 are formed on the substrate 120, and the second The common electrode 132 is formed below the substrate 130. That is, the liquid crystal layer 134 is on the substrate 1 It is sandwiched between 20 and the substrate 130. In addition, the pixel electrode 126 has an opening on the insulating layer 124. Because a (slit) is formed, multiple pixel electrodes 126 are shown in Figure 1(B). It is being done.

[0049] Furthermore, in the cross-sectional view shown in Figure 1(B), the liquid crystal element 111a is connected to the first common electrode 122 It is formed by the pixel electrode 126 and the liquid crystal layer 134. First common electrode 122 By applying a voltage between the pixel electrode 126, the orientation state of the liquid crystal layer 134 is controlled. It is possible. In addition, the liquid crystal element 111b has a second common electrode 132 and a pixel electrode 126. , formed by a liquid crystal layer 134 and between the second common electrode 132 and the pixel electrode 126 By applying a voltage, the orientation state of the liquid crystal layer 134 can be controlled. Furthermore, The liquid crystal element 111c applies a voltage between the first common electrode 122 and the second common electrode 132. This allows the alignment state of the liquid crystal layer 134 to be controlled. Also, as shown in Figure 1(A) The capacitive element 113 comprises a first common electrode 122, an insulating layer 124, and a pixel electrode 126. It is formed from the insulating layer 124, which functions as a dielectric layer for the capacitive element 113. .

[0050] Furthermore, in the cross-sectional view shown in Figure 1(B), the voltage applied to the liquid crystal layer 134 is shown by the arrow. It is expressed mathematically.

[0051] For example, 5.5V is applied to the pixel electrode 126, 0V to the first common electrode 122, and the second common By applying 0.8V to each of the electrodes 132, the liquid crystal element 11 shown in Figure 1(B) It is possible to drive 1. In this case, the first common electrode 122 and the second common electrode 132 Since the potential difference between them is 0.8V, the effect of the electric field of the liquid crystal element 111c shown in Figure 1(B) is It is small. On the other hand, there is a potential difference of 5.5V between the first common electrode 122 and the pixel electrode 126. Therefore, there is a potential difference of 4.7V between the pixel electrode 126 and the second common electrode 132. The orientation direction of the liquid crystals in the liquid crystal layer 134 is mainly determined by the potential between the first common electrode 122 and the pixel electrode 126. The difference is controlled, and furthermore, the potential applied to the second common electrode 132 controls the first common The contact electrode 122 and the pixel electrode 126 can assist in the alignment control of the liquid crystal element 111. Therefore, the first common electrode 122 and the second common electrode 132 each have independent power supplies. It is preferable that the connections be made via a wire and that each be controlled by an independent potential.

[0052] Thus, from the potential difference between the first common electrode 122 and the pixel electrode 126, the first common electrode By reducing the potential difference between 122 and the second common electrode 132, the transmittance of the liquid crystal layer 134 is reduced. Changes can be kept to a minimum.

[0053] Furthermore, the liquid crystal layer 134 of the liquid crystal element 111 uses a negative-type liquid crystal material and has resistance The rate is 1.0 × 10 13 Ω cm or more 1.0×10 16 It is preferable to keep it below Ω·cm.

[0054] Thus, the liquid crystal layer 134 is connected to the first common electrode 122, the pixel electrode 126, and the second common It is controlled by the three electrodes of electrode 132, and by using a negative-type liquid crystal, This minimizes changes in the transmittance of the liquid crystal layer 134, preventing flicker from being visible. This is possible. This is an excellent effect that can only be achieved in one aspect of the present invention.

[0055] Furthermore, in a liquid crystal display device according to one aspect of the present invention, the voltage V of the liquid crystal element 111 LC1 Hold Since this function can be handled by the capacitive element 113, the area of ​​the capacitive element 113 can be kept small. This makes it possible to keep the area of ​​the capacitive element 113 small while reducing the visibility of flicker. This can suppress the process. Therefore, it is possible to increase the resolution of pixels, and furthermore Furthermore, the interval at which image signals are written to pixels can be lengthened, thus reducing eye strain. This makes it possible to create an eye-friendly liquid crystal display.

[0056] <Example of panel configuration> Next, we will describe an example of a panel configuration, which corresponds to one form of liquid crystal display device.

[0057] The panel 230 shown in Figure 3 has a pixel section 231 with multiple pixels 100 and a row of pixels 100. For each selection, there are wirings GL1 to GLy (where y is a natural number) and wirings GL, Wiring SL1 to SLx (where x is self) for supplying an image signal to the selected pixel 100 Wiring SL, indicated by the number GL, is provided. The signal input to wiring GL is the drive circuit It is controlled by 232. The input of the image signal to wiring SL is controlled by the drive circuit 233. It is controlled. Multiple pixels 100 are connected to at least one of the wiring GL and at least one of the wiring SL They are each connected to another.

[0058] Furthermore, the type and number of wiring provided in the pixel section 231 are determined by the configuration, number and of the pixels 100. It can be determined by the arrangement. Specifically, in the case of the pixel section 231 shown in Figure 3, x rows × y Pixels 100 in a row are arranged in a matrix, with wiring SL1 to SLx, wiring GL This example illustrates the case where wiring 1 or GLy is located within the pixel section 231.

[0059] In one aspect of the present invention, the drive circuit 232 and the drive circuit 233 are made to operate intermittently. This significantly reduces the number of times the image signal is written to the pixel section 231 while maintaining the image display. This is possible. For example, a channel formation region containing a highly purified oxide semiconductor. When using the radiator 112, the frame duration should be 10 seconds or longer, preferably 30 seconds or longer. Furthermore, it can be made to 1 minute or more. Therefore, the drive circuit 232 and the drive circuit The drive frequency can be significantly reduced, thereby reducing the power consumption of the liquid crystal display. It is possible.

[0060] In one aspect of the present invention, an image signal is transmitted from the drive circuit 233 to wiring SL1 to SLx. You may also use sequential point drive, where the numbers are input in order, or you may use wiring SL1 to from the drive circuit 233. Alternatively, a sequential drive system that inputs image signals to all wiring SLx simultaneously may be used. A liquid crystal display device according to one embodiment of the liquid crystal display device sequentially inputs an image signal to each of the multiple wirings SL, and a drive method It is permissible to use the law.

[0061] Furthermore, the wiring GL can be selected using either a progressive or interlaced method. You may also use this.

[0062] Furthermore, the response time for liquid crystals, from the time a voltage is applied until its transmittance converges, is generally... It takes about 10-20 milliseconds. Therefore, the slow response time of the LCD is not visible as blurring in the video. Therefore, in one aspect of the present invention, the voltage applied to the liquid crystal element 111 is temporarily increased. It is also possible to use overdrive driving to rapidly change the orientation of the liquid crystal. - By using a drive-type system, the response speed of the LCD is increased, preventing blurring in videos and improving the image quality of the video. The quality can be improved.

[0063] Furthermore, even after transistor 112 becomes non-conductive, the transmission of liquid crystal element 111 If the rate does not converge and continues to change, the relative permittivity of the liquid crystal changes, thus maintaining the liquid crystal element 111. The voltage is prone to change. In particular, as in one aspect of the present invention, the liquid crystal element 111 is connected When the capacitance value of the capacitive element 113 is small, the voltage change held by the liquid crystal element 111 described above is This is particularly likely to occur. However, by using the overdrive function described above, the response time can be shortened. This allows the liquid crystal element after transistor 112 becomes non-conductive. The change in transmittance of 111 can be reduced. Therefore, in parallel with the liquid crystal element 111 Even if the capacitance value of the connected capacitive element 113 is small, the transistor 112 remains in a non-conductive state. After this occurs, it is possible to prevent the voltage held by the liquid crystal element 111 from changing.

[0064] Furthermore, the liquid crystal material used in the liquid crystal element 111 is a negative-type liquid crystal material with a resistivity of 1.0 × 1 0 13 Ω cm or more 1.0×10 16 Since it is less than Ω·cm, transistor 112 is non This prevents the voltage held by the liquid crystal element 111 from changing after it becomes conductive. .

[0065] <Example configuration of a liquid crystal display device> Next, an example of the configuration of a liquid crystal display device according to one aspect of the present invention will be described.

[0066] Figure 4 shows, as an example, a block diagram illustrating the configuration of a liquid crystal display device according to one aspect of the present invention. The liquid crystal display device 240 shown in Figure 4 has a panel 230 having multiple pixels 100 in the pixel section 231. It also includes a controller 241 and a power supply circuit 247. Furthermore, it has a liquid crystal display as shown in Figure 4. The unit 240 consists of an input device 242, a CPU 243, an image processing circuit 244, and an image memory 2 It has 45. Also, the liquid crystal display device 240 shown in Figure 4 has a panel 230 and a drive circuit 2 It has 32 and a drive circuit 233.

[0067] The controller 241 controls the operation of drive circuits 232 and 233, etc. It has the function of supplying various drive signals to the panel 230. The drive signals include the drive circuit 23 A start pulse signal for the drive circuit 233 that controls the operation of 3, and a clock signal for the drive circuit 233. A start pulse signal for the drive circuit 232 that controls the operation of the drive circuit 232, and a drive signal. This includes the clock signal for circuit 232, etc.

[0068] The input device 242 provides information and instructions to the CPU 243 of the liquid crystal display device 240. It has the function of, for example, switching the panel 230 from the operating state to the stopped state via the input device 242. A command to perform an action, or a command to transition the pixel unit 231 from a stopped state to an operating state. Instructions can be given to the CPU 243. Input devices 242 include a keyboard and a mouse. It can use touch panels, etc.

[0069] The CPU 243 decodes the instruction input from the input device 242 and displays it on the liquid crystal display device 24 It has the function of executing the instruction by comprehensively controlling the operation of various circuits that 0 possesses. .

[0070] For example, an input device 242 may issue a command to switch the pixel unit 231 from an operating state to a stopped state. When this is received, the CPU 243 sends the power supply voltage V from the power supply circuit 247 to the pixel unit 231. To stop the supply of p and also stop the supply of the drive signal to panel 230, A command is sent to controller 241.

[0071] Alternatively, an input device 242 may issue a command to transition the pixel unit 231 from a stopped state to an operating state. When this is received, the CPU 243 sends the power supply voltage V from the power supply circuit 247 to the pixel unit 231. The supply of p is restarted, and the supply of the drive signal to panel 230 is also restarted. The controller 241 is then given a command.

[0072] The image memory 245 contains data 246 which has image information input to the liquid crystal display device 240. It has the function of storing the image. Note that in Figure 4, only one image memory 245 is used in the liquid crystal display. The example shows the case where it is installed in 240, but multiple image memories 245 are installed in the liquid crystal display device 240. It may be included. For example, three data points corresponding to each hue, such as red, blue, and green. When a full-color image is displayed in the pixel section 231 by 246, the data 24 for each hue Alternatively, an image memory 245 corresponding to 6 may be provided for each.

[0073] Image memory 245 includes, for example, DRAM (Dynamic Random Access). s Memory), SRAM (Static Random Access Memo) Memory circuits such as ry can be used. Alternatively, VRAM (V You may also use ideo RAM.

[0074] The image processing circuit 244 processes the image data 246 according to the instructions from the controller 241. The process involves writing to memory 245 and reading data 246 from image memory 245. It has the function of generating an image signal from data 246.

[0075] In addition to supplying the power supply voltage Vp to the panel 230, the power supply circuit 247 also has the function of supplying the potential V COM 1 and potential V COM It has the function of supplying 2 to pixel 100.

[0076] <Top view of a pixel> Next, Figure 5 shows an example of a top view of pixel 100 shown in Figure 1(A). Note that in Figure 5, To clarify the top view of pixel 100, some components such as the gate insulating film have been omitted. This is illustrated. Also, the crossing between the dashed lines A1-A2 and A3-A4 shown in Figure 5. A cross-sectional view, corresponding to the cross-section, is shown in Figure 6.

[0077] The pixels 100 shown in Figures 5 and 6 are on a substrate 302 having an insulating surface, and a transistor 1 A conductive film 304 is provided, which has the function of a gate and a wiring GL. It is present. Also, on the substrate 302, there is a function as an electrode for the capacitive element 113 and a first common electrode. A first common electrode 318 is provided, which has the function of a first common electrode. Electrode 318 has a potential V COM1 It will be supplied.

[0078] Furthermore, an insulating film 306 is provided on the substrate 302 so as to cover the conductive film 304. Then, with the insulating film 306 in between, the transistor 112 is positioned where it overlaps with the conductive film 304. An oxide semiconductor film 308 that functions as a channel-forming region is provided. Conductive films 310 and 312 are provided on film 308. A conductive film 313 formed in the same process is provided on the insulating film 306. It functions as wiring SL and as the source or drain of transistor 112. The conductive film 312 functions as the source or drain of the transistor 112. It has the following properties. Furthermore, the conductive film 313 functions as a capacitance line.

[0079] Furthermore, on the insulating film 306, the oxide semiconductor film 308, and the conductive films 310, 312, and 313 An insulating film 314 is provided. And on the insulating film 314, a planarization film is provided. An insulating film 316 having conductivity is provided. In addition, insulating films 314 and 316 have a conductive film 3 An opening 360 reaching 12 is provided. In addition, conductive film 3 is provided on insulating films 314 and 316. An opening 362 reaching 13 is provided.

[0080] A first common electrode 318 is provided on the insulating film 316. It is connected to the conductive film 313 through the opening 362. Also, the insulating film 316 and An insulating film 320 is provided on the common electrode 318 of 1, and on the insulating film 320, A pixel electrode 322 is provided at a position that overlaps with the common electrode 318 of 1. It has an opening 364 in a position that overlaps with the opening 360, and through the openings 360 and 364 The conductive film 312 and the pixel electrode 322 are connected. Note that the pixel electrode 322 is as shown in Figure 5. As shown in the top view, it has an opening (slit). Also, insulating film 320 and pixel electricity An alignment film 324 is provided on the pole 322.

[0081] Furthermore, a substrate 330 is provided so as to face the substrate 302. Below the substrate 330 It includes a light-shielding film 332 that has the function of blocking visible light, and a material that transmits visible light in a specific wavelength range. A color film 334, an insulating film 336 in contact with the light-shielding film 332 and the colored film 334, and the insulating film 336 A second common electrode 338 that is in contact with the second common electrode 338 and an alignment film 340 that is in contact with the second common electrode 338 are provided. The insulating film 336 has a surface shape that is the same as the light-shielding film 332 and the colored film 334. It has the function of suppressing the impairing of the flatness of the conductive electrode 338 or the alignment film 340. The edge film 336 may be omitted.

[0082] Then, between substrate 302 and substrate 330, it is sandwiched between alignment films 324 and 340. In addition, a liquid crystal layer 350 containing liquid crystal material is provided. The liquid crystal element 111 is at least Common electrode 318, insulating film 320, pixel electrode 322, second common electrode 338, and liquid crystal It has a layer 350. The liquid crystal layer 350 uses a negative-type liquid crystal material, and the intrinsic resistance of the liquid crystal material The resistance rate is 1.0 × 10⁻⁶ 13 Ω cm or more 1.0×1016 It is less than or equal to Ω·cm.

[0083] <Manufacturing Method> Next, an example of a pixel fabrication method shown in Figure 6 will be explained using Figures 7 and 8. .

[0084] As shown in Figure 7(A), after forming a conductive film on the substrate 302, the conductive film is etched. A conductive film 304 is formed by processing the shape using a tool or the like. Next, an insulating film is applied to the conductive film 304. A border film 306 is formed. Next, an oxide semiconductor film is formed on the insulating film 306, and then the oxide The semiconductor film is shaped by etching or other means, and separated into island-like structures at positions overlapping with the conductive film 304. A modified oxide semiconductor film 308 is formed.

[0085] The substrate 302 is preferably a substrate with sufficient heat resistance to withstand subsequent manufacturing processes. For example, glass substrates, ceramic substrates, quartz substrates, sapphire substrates, etc., are used. .

[0086] The conductive film 304 can be aluminum, titanium, chromium, cobalt, nickel, copper, etc. Ruthenium, zirconium, molybdenum, ruthenium, silver, tantalum, and tungsten It is preferable to use a film made of one or more conductive materials containing one or more types, laminated in one or more layers. The conductive film 304 may be a conductive film in which a copper film is laminated on a tungsten nitride film, or a single layer of tungsten A stainless steel film can be used.

[0087] The insulating film 306 can be aluminum oxide, magnesium oxide, silicon oxide, or nitrile oxide. Silicon oxide, silicon nitride, silicon nitride, gallium oxide, germanium oxide, oxide Yttrium, zirconium oxide, lanthanum oxide, neodymium oxide, hafnium oxide, and acid An insulating film containing one or more types of tantalum oxide can be used as a single layer or in a laminated configuration.

[0088] For example, if the insulating film 306 has a two-layer structure, the first layer is a silicon nitride film, and the second layer is A multilayer film made of silicon oxide film can be used. The second layer of silicon oxide film is silicon oxide nitride. It can be made into a film. Also, the first layer of silicon nitride film can be made into a silicon nitride oxide film. It is possible.

[0089] It is preferable to use a silicon oxide film with a low defect density. Specifically, , using electron spin resonance (ESR) The spin density of the spins originating from the signal with a value of 2.001 is 3 × 10⁻¹⁰ 17 spins / cm 3 The following is preferably 5 × 10 16 spins / cm 3 The following silicon oxide film is used. For the silicon oxide film, it is preferable to use a silicon oxide film that has an excess of oxygen. The film used is a silicon nitride film, which emits less hydrogen and ammonia. The amount released is TDS (Thermal Desorption Spectroscopy). y: This can be measured by thermal desorption gas spectroscopy.

[0090] The materials that can be used for the oxide semiconductor film 308 are described in detail in Embodiment 2. It is included. Furthermore, the oxide semiconductor film used as oxide semiconductor film 308 contains a large amount of hydrogen. Then, when the oxide semiconductor and hydrogen combine, some of the hydrogen becomes a donor, and carrier This generates electrons, causing the transistor's threshold voltage to turn negative. It shifts to this. Therefore, after the formation of the oxide semiconductor film, dehydration treatment (dehydrogenation) is performed. (Chemical treatment) is performed to remove hydrogen or water from the oxide semiconductor film, resulting in a film that contains as few impurities as possible. It is preferable to do so.

[0091] Furthermore, by dehydrating (dehydrogenating) the oxide semiconductor film, Oxygen levels may decrease. Therefore, dehydration treatment (dehydrogenation treatment) of oxide semiconductor films is necessary. To compensate for the increased oxygen deficiency caused by the process, oxygen is added to the oxide semiconductor film. It is preferable.

[0092] Thus, oxide semiconductor films undergo dehydration treatment (dehydrogenation treatment) to remove hydrogen or water. The oxygen deficiency is removed and compensated for by oxygenation treatment, resulting in type i (true) and This can be an oxide semiconductor film that is very close to type i and is essentially type i (intrinsic).

[0093] Next, as shown in Figure 7(B), a conductive film is applied to the insulating film 306 and the oxide semiconductor film 308. After formation, the shape of the conductive film is processed by etching or other means to form an oxide semiconductor. A conductive film 310, 312 is formed in contact with film 308. A conductive film 313 is formed on the insulating film 306 using the same process as the previous step.

[0094] Examples of conductive films 310, 312, and 313 include aluminum, titanium, chromium, and nickel. Copper, copper, yttrium, zirconium, molybdenum, silver, tantalum, or tungsten A single metal consisting of tene, or an alloy with tene as the main component, in a single-layer or laminated structure. It can be used. For example, a two-layer structure in which a titanium film is laminated on an aluminum film, tang A two-layer structure with a titanium film laminated on top of a stainless steel film, and a copper-magnesium-aluminum alloy film. A two-layer structure consisting of a copper film, a titanium film or titanium nitride film, and the titanium film or titanium nitride film An aluminum film or copper film is laminated on top of the aluminum film, and then a titanium film or nitride film is placed on top of that. A three-layer structure forming a titanium film, a molybdenum film or molybdenum nitride film, and the molybdenum An aluminum film or copper film is laminated on top of the film or molybdenum nitride film, and further on There are three-layer structures that form a molybdenum film or molybdenum nitride film. Transparent conductive materials containing um, tin oxide, or zinc oxide may be used. Furthermore, the conductive film may be, for example... Alternatively, it can be formed using the sputtering method.

[0095] Next, as shown in Figure 7(C), insulating film 306, oxide semiconductor film 308, and conductive film 3 An insulating film 314 is formed on 10, 312, and 313.

[0096] As the insulating film 314, for example, it is placed in the vacuum-evacuated processing chamber of a plasma CVD apparatus. The substrate is heated to a temperature of 180°C to 400°C, more preferably 200°C to 370°C. Maintain the pressure within the processing chamber by introducing the raw material gas into the processing chamber and adjusting the pressure between 30 Pa and 250 Pa. Furthermore, the pressure is preferably 40 Pa or more and 200 Pa or less, and the electrode provided in the processing chamber is high Depending on the conditions under which frequency power is supplied, a silicon oxide film or a silicon oxide nitride film is formed.

[0097] As the raw material gas for the insulating film 314, a silicon-containing depositing gas and an oxidizing gas are used. This is preferable. Typical examples of silicon-containing sedimentary gases include silane, disilane, and tri Examples include silanes and silane fluorides. Oxidizing gases include oxygen, ozone, nitrous oxide, and dinitrate. Examples include nitric oxide.

[0098] In this embodiment, the insulating film 314 is a laminated structure of a first insulating film and a second insulating film. For example, as the first insulating film, silane at a flow rate of 20 sccm and silane at a flow rate of 3000 sccm Using nitrous oxide as the raw material gas, the pressure in the processing chamber was set to 40 Pa, and the substrate temperature was set to 220°C. A 7.12MHz high-frequency power supply was used to supply 100W of high-frequency power to parallel plate electrodes. A silicon oxide-nitride film with a thickness of 50 nm is formed using the plasma CVD method. The CVD apparatus has an electrode area of ​​6000 cm². 2 It is a parallel-plate type plasma CVD apparatus, Converting the supplied power to power per unit area (power density) gives 1.6 × 10⁻⁶ -2 W / c m 2 Under these conditions, an oxygen-permeable silicon oxidnitride film can be formed. ru.

[0099] The second insulating film is applied to a substrate placed in the vacuum-evacuated processing chamber of a plasma CVD apparatus. Maintain the temperature between 80°C and 260°C, more preferably between 180°C and 230°C, in the processing chamber. The raw material gas is introduced and the pressure inside the processing chamber is set to between 100 Pa and 250 Pa, and furthermore, The pressure should be between 100 Pa and 200 Pa, and 0.17 W / cm 2 More than 0.5W / cm 2 More preferably, 0.25 W / cm² 2 More than 0.35W / cm 2 Under the following conditions for supplying high-frequency power, silicon oxide film or silicon oxide nitride film It forms a film.

[0100] As a film deposition condition for the second insulating film, the high-frequency current at the above power density is used in the pressure processing chamber. 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 second insulating film becomes greater than the stoichiometric composition. The amount also increases. However, if the substrate temperature is the above temperature, the bonding force between silicon and oxygen Because it is weak, some of the oxygen is removed by heating. As a result, the oxygen that satisfies the stoichiometric composition... It can form an oxide insulating film that contains more oxygen, and some of the oxygen is removed by heating. Cut.

[0101] In this embodiment, the second insulating film is silane at a flow rate of 160 sccm and 400 sccm Using 0 sccm of nitrous oxide as the raw material gas, the pressure in the processing chamber was set to 200 Pa, and the substrate temperature was set to 22 At 0°C, a 27.12MHz high-frequency power supply is used to apply 1500W of high-frequency power to a parallel plate power supply. A 400 nm thick silicon oxide nitride film is formed by plasma CVD supplied to the electrode. The plasma CVD apparatus has an electrode area of ​​6000 cm². 2 This is a parallel plate type plasma C This is a VD device, and when the supplied power is converted to power per unit area (power density), it is 2.5 ×10 -1 W / cm 2 That is the case.

[0102] Next, after forming at least an insulating film 314, a heat treatment is performed, and the insulating film 314 contains The oxygen is transferred to the oxide semiconductor film 308, and the oxygen vacancies in the oxide semiconductor film 308 are filled. It is preferable to do so.

[0103] Next, as shown in Figure 7(D), a desired region of the insulating film 314 is processed and the conductive film 312 is formed. An opening 360 that reaches the conductive film 313 is formed, along with an opening 362 that reaches the conductive film 313.

[0104] For example, the method for forming the openings 360 and 362 is a dry etching method or a wet etching method. The wet etching method is used. Additionally, a combination of the dry etching method and the wet etching method is employed. Openings 360 and 362 may be formed.

[0105] Next, as shown in Figure 8(A), an insulating film 316 having an opening is formed. 6 has openings at positions corresponding to openings 360 and 362. The insulating film 316 is first This is a film that forms the base for the common electrode 318, and the first common electrode is formed by transistors, conductive films, etc. It has the function of preventing the formation of irregularities on 318. In other words, it has the function of a planarizing film. The insulating film 316 can be made of an acrylic resin, a polyimide resin, or the like.

[0106] Next, as shown in Figure 8(B), a first common electrode 318 is formed on the insulating film 316. Subsequently, an insulating film 320 is formed to cover the insulating film 316 and the first common electrode 318. The first common electrode 318 is connected to the conductive film 313 through the opening 362.

[0107] The first common electrode 318 is, for example, an indium oxide containing tungsten oxide. Indium zinc oxide containing tungsten oxide, indium oxide containing titanium oxide, acid Titanium oxide-containing indium tin oxide, indium tin oxide, indium zinc oxide, oxide A conductive film containing silicon-added indium tin oxide, etc., can be used. The common electrode 318 can be formed using the sputtering method.

[0108] The insulating film 320 includes silicon oxide film, silicon oxide nitride film, silicon nitride film, and nitride A silicon oxide film or the like can be used. In particular, the insulating film 320 is the dielectric of the capacitive element. Because it has the function of both a protective film for transistors and a protective film for transistors, as an insulating film, nitrogen A silicon oxide film or silicon nitride film is preferred.

[0109] For example, the insulating film 320 is a silicon nitride film with a thickness of 50 nm or more and 400 nm or less. Alternatively, a silicon nitride film or the like can be used. In this embodiment, insulating film 32 As a baseline of 0, a silicon nitride film with a thickness of 100 nm is used.

[0110] Furthermore, the silicon nitride film is preferably deposited at a high temperature to enhance its blocking properties. For example, the substrate temperature should be 100°C or higher and below the substrate's strain point, more preferably 300°C or higher. It is preferable to form the film by heating at a temperature of 0°C or lower. However, when forming the film at high temperatures, acid Oxygen may be released from the ionized semiconductor film 308, causing an increase in carrier concentration. Therefore, the temperature should be set so that this phenomenon does not occur.

[0111] Next, as shown in Figure 8(C), an opening 364 is formed in the insulating film 320. 4 is formed in the region located at the opening 360 formed in the insulating film 316. The portion 364 is formed so that the conductive film 312 is exposed. The method for forming the opening 364 is as follows: The openings 360 and 362 can be formed by using the method described herein.

[0112] Next, as shown in Figure 8(D), a pixel electrode 322 is formed on the insulating film 320. The pixel electrode 322 is connected to the conductive film 312 via apertures 360 and 364.

[0113] The pixel electrode 322 is formed by forming a transparent conductive film on the insulating film 320 and processing the shape of the transparent conductive film by etching or the like.

[0114] As the pixel electrode 322, usable materials include indium oxide containing tungsten oxide, indium zinc oxide containing tungsten oxide, indium oxide containing titanium oxide, indium tin oxide containing titanium oxide, indium tin oxide, indium zinc oxide, and indium tin oxide doped with silicon oxide, and a conductive film formed of any of the above materials can be used.

[0115] Next, an alignment film 324 is formed on the insulating film 320 and the pixel electrode 322 (not shown). The alignment film 324 can be formed by a rubbing method, a photo-alignment method, or the like.

[0116] Through the above steps, the structure formed on the substrate 302 can be obtained.

[0117] Next, a method for manufacturing a structure formed below the substrate 330 provided opposite to the substrate 302 will be described below.

[0118] First, the substrate 330 is prepared. For the substrate 330, the materials listed for the substrate 302 can be used. Next, a light shielding film 332 and a colored film 334 in contact with the substrate 330 are formed. The light shielding film 332 and the colored film 334 are each formed at desired positions using various materials by a printing method, an inkjet method, an etching method using photolithography technology, or the like.

[0119] Next, an insulating film 336 in contact with the light shielding film 332 and the colored film 334 is formed. For the insulating film 336, for example, an organic insulating film such as an acrylic resin can be used. By forming this, for example, impurities contained in the colored film 334 are transferred to the liquid crystal layer 350 side. This can suppress its spread.

[0120] Next, a second common electrode 338 is formed in contact with the insulating film 336. Examples of conductive films that can be used include indium oxide containing tungsten oxide, and oxide Indium zinc oxide containing tungsten, indium oxide containing titanium oxide, titanium oxide Indium tin oxide containing tan, indium tin oxide (hereinafter referred to as ITO), indium Translucent conductive materials such as zinc oxide and indium tin oxide with added silicon oxide. A conductive material can be used. Also, a conductive layer that can be used for the second common electrode 338. For example, it can be formed using the sputtering method.

[0121] Next, an alignment film 340 is formed in contact with the second common electrode 338. The method can be used to form the orientation film 324.

[0122] The above process allows for the formation of the structure located beneath the substrate 330.

[0123] Subsequently, a liquid crystal layer 350 is formed between substrate 302 and substrate 330. Formation methods include the dispenser method (dropping method) and bonding substrate 302 and substrate 330. An injection method can be used in which liquid crystal is injected using capillary action.

[0124] By following the above steps, the pixels shown in Figure 6 can be produced.

[0125] The configurations and methods described in this embodiment are similar to those described in other embodiments. They can be used in combination as appropriate.

[0126] (Embodiment 2) In this embodiment, an oxide that can be used in a liquid crystal display device according to one aspect of the present invention. This section will explain semiconductor films.

[0127] Impurities such as water or hydrogen, which act as electron donors, are reduced, and oxygen is depleted. By reducing losses, the oxide semiconductor (purified OS) achieves high purity. It is a type i (intrinsic semiconductor) or very close to type i. Therefore, it is a highly purified oxide semiconductor film. Transistors with a channel formation region have significantly low off-current and high reliability.

[0128] Specifically, a transistor having a channel formation region in a highly purified oxide semiconductor film The low off-current can be proven through various experiments. For example, if the channel width is 1× 10 6 Even with a device that is μm in size and has a channel length of 10 μm, the electrical current between the source electrode and the drain electrode In the voltage (drain voltage) range of 1V to 10V, the off-current is due to the semiconductor parameter A Below the measurement limit of the analyzer, i.e., 1 × 10⁻⁶ -13 The characteristic of being A or less can be obtained. In this case, the off-current normalized by the transistor's channel width is 100 Hz / μm or less. It can be seen that... Also, by connecting the capacitive element and the transistor, the current flows into the capacitive element... This circuit uses a transistor to control the charge flowing out of a capacitive element, and measures the off-current. The measurement was performed. In this measurement, the highly purified oxide semiconductor film was used as the channel of the transistor. Used in the region where the charge is formed, the change in the amount of charge per unit time of the capacitive element is used to determine the transistor's operation. The off current was measured. As a result, when the voltage between the source electrode and the drain electrode of the transistor is 3 V , it was found that an even smaller off-current of several tens of yA / μm can be obtained. Accord ingly, a transistor using a highly purified oxide semiconductor film for a channel formation region has an off current that is significantly smaller than that of a transistor using crystalline silicon.

[0129] Note that unless otherwise specified, off-current in this specification refers to, in an n-channel transistor , a current that flows between a source and a drain when the drain is at a higher potential than the source and the gate, and the gate potential is 0 or lower with the source potential used as a reference. Alternatively, off-current in this specification refers to, in a p-channel transistor , a current that flows between a source and a drain when the drain is at a lower potential than the source and the gate, and the gate potential is 0 or higher with the source potential used as a reference. is 0 or higher with the source potential used as a reference, a current flowing between the source and the drain is meant.

[0130] Note that an oxide semiconductor preferably contains at least indium (In) or zinc (Zn) . In addition, as a stabilizer for reducing variation in electrical characteristics of the transistor, it is preferable to further contain gallium (Ga) in addition to the above. In addition, it is preferable to contain tin (Sn) as a stabilizer . In addition, it is preferable to contain hafnium (Hf) as a stabilizer. In addition, it is preferable to contain aluminum ( Al) as a stabilizer. In addition, it is preferable to contain zirconium (Zr) as a stabilizer . it is preferable to contain the above.

[0131] Among oxide semiconductors, In-Ga-Zn oxides and In-Sn-Zn oxides are, Unlike silicon carbide, gallium nitride, or gallium oxide, sputtering and wet processes The method makes it possible to manufacture transistors with excellent electrical characteristics, and it is highly productive for mass production. These are some of the advantages. Also, unlike silicon carbide, gallium nitride, or gallium oxide... Furthermore, the above In-Ga-Zn oxide is used on a glass substrate to form a transistor with excellent electrical properties. It is possible to manufacture the board. Furthermore, it can accommodate larger substrates.

[0132] Other stabilizers include lanthanides such as lanthanum (La) and cerium. (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europieu Eu, Gadolinium (Gd), Terbium (Tb), Dysprosium (Dy), Ho Lumium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), It may contain one or more types of lutetium (Lu).

[0133] For example, oxide semiconductors include indium oxide, gallium oxide, tin oxide, zinc oxide, In-Zn oxides, Sn-Zn oxides, Al-Zn oxides, Zn-Mg oxides, Sn-Mg oxides, In-Mg oxides, In-Ga oxides, In-Ga-Zn oxides In-Al-Zn oxides (also written as IGZO), In-Sn-Zn oxides Sn-Ga-Zn oxides, Al-Ga-Zn oxides, Sn-Al-Zn oxides, In-Hf-Zn oxides, In-La-Zn oxides, In-Pr-Zn oxides, I n-Nd-Zn oxides, In-Sm-Zn oxides, In-Eu-Zn oxides, In -Gd-Zn oxides, In-Tb-Zn oxides, In-Dy-Zn oxides, In- Ho-Zn oxides, In-Er-Zn oxides, In-Tm-Zn oxides, In-Y b-Zn oxides, In-Lu-Zn ​​oxides, In-Sn-Ga-Zn oxides, In -Hf-Ga-Zn oxides, In-Al-Ga-Zn oxides, In-Sn-Al-Z n-based oxides, In-Sn-Hf-Zn-based oxides, and In-Hf-Al-Zn-based oxides are used. It is possible.

[0134] For example, an In-Ga-Zn oxide is an oxide containing In, Ga, and Zn. This is the meaning, and the ratio of In, Ga, and Zn is irrelevant. Also, the metal elements other than In, Ga, and Zn are not relevant. It may contain elements. In-Ga-Zn oxides have sufficiently high resistance in the absence of an electric field and are off It is possible to reduce the current to a sufficiently small level, and it also has high mobility.

[0135] For example, In:Ga:Zn=1:1:1, In:Ga:Zn=1:1:1.2 (5:5 :6), atomic ratios such as In:Ga:Zn=2:2:1, In:Ga:Zn=3:1:2 In-Ga-Zn oxides or oxides with a similar composition can be used. In:Sn:Zn=1:1:1, In:Sn:Zn=2:1:3 or In:Sn: In-Sn-Zn oxides with an atomic ratio of Zn=2:1:5 or oxides with a similar composition are used. It would be good to have one.

[0136] For example, high mobility can be obtained relatively easily with In-Sn-Zn oxides. However, However, even with In-Ga-Zn oxides, mobility can be increased by reducing the bulk defect density. It can be raised.

[0137] Oxide semiconductor films are broadly classified into non-single-crystal oxide semiconductor films and single-crystal oxide semiconductor films. Non-single-crystal oxide semiconductor films are CAAC-OS (C Axis Aligned Crystal Stalline Oxide Semiconductor film, polycrystalline oxide semiconductor This refers to films, microcrystalline oxide semiconductor films, amorphous oxide semiconductor films, etc.

[0138] This section describes the CAAC-OS membrane.

[0139] CAAC-OS film is one of the oxide semiconductor films having multiple crystalline regions, and most The crystalline portion is small enough to fit within a cube with sides less than 100 nm. Therefore, CAAC- The crystalline portion contained in the OS film is a cube with sides of less than 10 nm, less than 5 nm, or less than 3 nm. This also includes cases where the item fits inside.

[0140] CAAC-OS film is examined using a transmission electron microscope (TEM). When observed with a tron ​​microscope, a clear boundary between crystalline regions is observed, i.e. The grain boundaries (also called crystal grain boundaries) cannot be identified. Therefore, C AAC-OS films are less susceptible to the decrease in electron mobility caused by grain boundaries.

[0141] 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. The shape reflects a convexity and is arranged parallel to the surface or top surface of the CAAC-OS film to be formed.

[0142] 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.

[0143] In this specification, "parallel" means that two lines are at an angle of -10° or more and 10° or less. This refers to a state in which the positions are arranged. Therefore, it also includes cases where the angle is between -5° and 5°. Also, "Perpendicular" refers to a state where two straight lines are positioned at an angle between 80° and 100°. Therefore, this also includes cases where the angle is between 85° and 95°.

[0144] 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.

[0145] X-ray diffraction (XRD) of CAAC-OS film When structural analysis is performed using the instrument, for example, CAAC-OS has crystals of InGaZnO4. Out-of-plane analysis of the film showed a peak at a diffraction angle (2θ) of around 31°. This peak may appear. This peak is attributed to the (009) plane of the InGaZnO4 crystal. Therefore, the crystals of the CAAC-OS film have c-axis orientation, and the c-axis is on the surface to be formed or on the upper surface. It can be confirmed that it is oriented in a roughly vertical direction.

[0146] 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 InGaZnO4 crystal. For a semiconductor film, fix 2θ to around 56° and use the normal vector of the sample surface as the axis (φ axis). When the analysis (φ scan) is performed while rotating the sample, a crystal plane equivalent to the (110) plane is found. Six peaks attributable to this are observed. In contrast, in the case of the CAAC-OS film, 2θ Even when fixed at approximately 56° and scanned using the φ scan function, no clear peak appears.

[0147] From the above, 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.

[0148] 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 crystal is aligned with the surface on which the CAAC-OS film is formed. Or it is oriented in a direction parallel to the normal vector of the upper surface. Therefore, for example, the CAAC-OS film When the shape is altered by etching or other means, the c-axis of the crystal becomes the target area for CAAC-OS film formation. The normal vector may not be parallel to the normal vector of the face or top surface.

[0149] 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.

[0150] Furthermore, the out-of-plane CAAC-OS film having InGaZnO4 crystals Analysis using this method revealed that in addition to the peak near 2θ = 31°, there is also a peak near 2θ = 36°. In some cases, this occurs. Peaks near 2θ of 36° are found on the (311) plane of the ZnGa2O4 crystal. Since it is attributed to this, a portion of the CAAC-OS film containing InGaZnO4 crystals contains Z This indicates the presence of nGa2O4 crystals. The CAAC-OS film has a 2θ of nearly 31°. It is preferable that the peak is shown to the side and that the peak does not appear near 36° for 2θ.

[0151] 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.

[0152] 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.

[0153] 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.

[0154] Furthermore, transistors using CAAC-OS films exhibit electrical properties when irradiated with visible light or ultraviolet light. Sexual variation is small.

[0155] CAAC-OS films are made using, for example, a polycrystalline metal oxide target, and sputtering The film is formed by a collidermation method. When ions collide with the target, the ions contained in the target The crystalline region is cleaved from the ab plane and has a plate-like or pellet-like shape with a plane parallel to the ab plane. The material may detach as sputtering particles. In this case, the flat plate or pellet-shaped material may detach. The sputtered particles reach the substrate while maintaining their crystalline state, resulting in CAAC-OS A film can be formed.

[0156] Furthermore, it is preferable to apply the following conditions for forming the CAAC-OS film.

[0157] By reducing the inclusion of impurities during film formation, it is possible to suppress the disruption of the crystalline state due to impurities. For example, the concentration of impurities present in the processing room (hydrogen, water, carbon dioxide, and nitrogen, etc.) It should be reduced. Also, the concentration of impurities in the film-forming gas should be reduced. Specifically, the dew point A film-forming gas with a temperature of -80°C or lower, preferably -100°C or lower, is used.

[0158] Furthermore, by increasing the substrate heating temperature during film deposition, the sputtering particles can be removed after reaching the substrate. Grazing occurs. Specifically, the substrate heating temperature is preferably between 100°C and 740°C. The film is deposited at a temperature of 200°C to 500°C. By increasing the substrate heating temperature during film deposition, When flat or pellet-shaped sputtering particles reach the substrate, migrain occurs on the substrate. A stun occurs, and the flat surface of the sputtered particles adheres to the substrate.

[0159] Furthermore, by increasing the oxygen content in the deposition gas and optimizing the power, plasma damage during film deposition can be reduced. It is preferable to reduce the amount of oxygen. The oxygen content in the film-forming gas is 30% by volume or more, preferably 100%. This is expressed as a percentage by volume.

[0160] Furthermore, the oxide semiconductor layer may have a stacked structure.

[0161] Here, the oxide semiconductor film 308 used in the transistor 112 shown in Figure 6 is an oxide semiconductor film An example of a stacked structure of body film 307 and oxide semiconductor film 309 will be explained using Figure 9. To do so.

[0162] Furthermore, Figure 9(A) shows the oxide semiconductor film used in transistor 112, which is an oxide semiconductor film. This is a cross-sectional structure with a stacked structure of 307 and oxide semiconductor film 309. Therefore, other The configuration is the same as that of transistor 112 shown in Figure 6, and the previous explanation can be considered. ru.

[0163] The oxide semiconductor film 307 and the oxide semiconductor film 309 have at least one identical constituent element. It is preferable to use a metal oxide. Alternatively, an oxide semiconductor film 307 and an oxide semiconductor film The constituent elements of 309 may be the same, but the compositions of the two may be different.

[0164] The oxide semiconductor film 307 is In-M-Zn oxide (where M is Al, Ga, Ge, Y, Zr, S). For n, La, Ce, or Hf, the spars used to deposit In-M-Zn oxide films are used. The atomic ratio of the metal elements in the tarring target is preferably such that In ≥ M and Zn ≥ M. It is so. The atomic ratio of metal elements in such a sputtering target is In:M:Z n=1:1:1, In:M:Zn=5:5:6(1:1:1.2), In:M:Zn=3 A ratio of 1:2 is preferred. Note that the atomic ratios of the oxide semiconductor film 307 to be formed are as follows: The difference is the positive or negative atomic ratio of the metal elements contained in the sputtering target mentioned above. Includes a 20% fluctuation.

[0165] Furthermore, when the oxide semiconductor film 307 is an In-M-Zn oxide, Zn and O are excluded. The atomic ratio of In to M is preferably 25 atomic% or more for In and 75 atomic% for M. Less than 0 omic%, more preferably In is 34 atomic% or more, and M is 66 atomic%. It should be less than c%.

[0166] The oxide semiconductor film 307 has an energy gap of 2 eV or more, preferably 2.5 eV or less. More preferably, it is 3 eV or more. Thus, oxide semiconductors with a wide energy gap By using a conductor, the off-current of transistor 112 can be reduced.

[0167] The thickness of the oxide semiconductor film 307 is 3 nm or more and 200 nm or less, preferably 3 nm or more. The wavelength should be 00 nm or less, and more preferably 3 nm to 50 nm.

[0168] Oxide semiconductor films 309 are typically In-Ga oxide, In-Zn oxide, In- M-Zn oxide (where M is Al, Ga, Ge, Y, Zr, Sn, La, Ce, or Hf) Furthermore, the energy at the lower end of the conduction band is closer to the vacuum level than that of the oxide semiconductor film 307, and representatively... Specifically, the energy at the lower end of the conduction band of the oxide semiconductor film 309 and the energy of the oxide semiconductor film 307 The energy difference from the lower end of the conduction band is 0.05 eV or more, 0.07 eV or more, and 0.1 eV. Above, or 0.15 eV or more and 2 eV or less, 1 eV or less, 0.5 eV or less, It is 0.4 eV or less. That is, the electron affinity of the oxide semiconductor film 309 and the oxide semiconductor film 3 The difference from the electron affinity of O7 is 0.05 eV or more, 0.07 eV or more, 0.1 eV or more, or 0.15eV or more, and 2eV or less, 1eV or less, 0.5eV or less, or 0.4eV It is less than or equal to V.

[0169] The oxide semiconductor film 309 has the aforementioned element M in a higher atomic ratio than In, which means that the following It may have an effect. (1) It increases the energy gap of the oxide semiconductor film 309. (2) Reduce the electron affinity of the oxide semiconductor film 309. (3) Remove impurities from the outside. It shields. (4) Compared to the oxide semiconductor film 307, it has higher insulating properties. Also, element M is Because it is a metallic element with a strong bonding force with oxygen, by having M in a higher atomic ratio than In, Oxygen deficiency becomes less likely.

[0170] When the oxide semiconductor film 309 is an In-M-Zn oxide, I is present excluding Zn and O. The atomic ratio of n to M is preferably less than 50 atoms for In and 50 atoms for M. ic% or more, more preferably In is less than 25 atomic%, and M is 75 atomic% It must be % or greater.

[0171] Furthermore, oxide semiconductor film 307 and oxide semiconductor film 309 are In-M-Zn oxide (M In the case of Al, Ga, Ge, Y, Zr, Sn, La, Ce or Hf, oxide semiconductor film Compared to 307, the atomic ratio of M contained in oxide semiconductor film 309 is larger, and typically Compared to the atoms contained in the oxide semiconductor film 307, the amount is 1.5 times or more, preferably 2 times. More preferably, the atomic ratio is three times higher or more.

[0172] Furthermore, the oxide semiconductor film 309 is oxidized in In:M:Zn=x1:y1:z1 [atomic ratio]. If the semiconductor film 307 is represented as In:M:Zn=x2:y2:z2 [atomic ratio], then y1 / x 1 is greater than y2 / x2, preferably y1 / x1 is 1.5 times or more than y2 / x2. It is more preferably that y1 / x1 is at least twice as large as y2 / x2. In this case, y1 / x1 is more than 3 times larger than y2 / x2. And, if y2 is greater than or equal to x2, the transistor 102 using the oxide semiconductor film becomes stable. It is preferable because it can impart certain electrical properties. However, if y2 becomes 3 times or more than x2, the acid Because the field-effect mobility of transistor 102 using the ionized semiconductor film decreases, y2 It is preferable that x is less than 3 times x2.

[0173] When the oxide semiconductor film 309 is In-M-Zn oxide, the In-M-Zn oxide film is deposited. The atomic ratio of the metal elements in the sputtering target used for this purpose is M > In, and furthermore Z It is preferable that n≧M be satisfied. The atoms of the metal element in such a sputtering target In terms of numerical ratios, In:Ga:Zn = 1:3:2, In:Ga:Zn = 1:3:3, In:G a:Zn=1:3:4, In:Ga:Zn=1:3:5, In:Ga:Zn=1:3:6 , In:Ga:Zn=1:3:7, In:Ga:Zn=1:3:8, In:Ga:Zn= 1:3:9, In:Ga:Zn=1:3:10, In:Ga:Zn=1:6:4, In: Ga:Zn=1:6:5, In:Ga:Zn=1:6:6, In:Ga:Zn=1:6: 7, In:Ga:Zn=1:6:8, In:Ga:Zn=1:6:9, In:Ga:Zn A ratio of 1:6:10 is preferred. Furthermore, the acid film deposited using the above sputtering target... The atomic ratios of the metal elements contained in the oxide semiconductor film 307 and the oxide semiconductor film 309 are as follows: Therefore, the positive value of the atomic ratio of the metal elements contained in the sputtering target is an error. Includes a 20% fluctuation in index.

[0174] Furthermore, this is not limited to the semiconductor characteristics and electrical characteristics (field effect) of the transistor as needed. A suitable composition should be used depending on the fruit mobility, threshold voltage, etc. To obtain the semiconductor characteristics of the transistor, the carrier density and impurities of the oxide semiconductor film 307 are important. The concentration of the material, defect density, atomic ratio of metal elements to oxygen, interatomic distance, density, etc., should be appropriate. It is preferable.

[0175] The oxide semiconductor film 309 is used when forming the insulating film 314 which will be formed later. It also functions as a damage mitigation film for 307. The thickness of the oxide semiconductor film 309 is 3 nm or less. The wavelength should be 100 nm or less, preferably between 3 nm and 50 nm.

[0176] In the oxide semiconductor film 307 contained in transistor 112, one of the group 14 elements is When certain silicon or carbon is present, oxygen vacancies increase in the oxide semiconductor film 307, n It becomes molded. Therefore, the concentration of silicon and carbon in the oxide semiconductor film 307, This refers to the concentration of silicon and carbon near the interface between the oxide semiconductor film 309 and the oxide semiconductor film 307. (Concentration obtained by secondary ion mass spectrometry) is 2 × 10 18 atoms / cm 3 below Preferably 2 × 10 17 atoms / cm 3 The following applies:

[0177] Furthermore, in the oxide semiconductor film 307, alkali obtained by secondary ion mass spectrometry is also present. The concentration of metal or alkaline earth metal is 1 × 10⁻⁶ 18 atoms / cm 3 The following are preferable is 2 x 10 16 atoms / cm 3 The following applies: Alkali metals and alkaline earth metals are: When combined with oxide semiconductors, it can generate carriers, increasing the transistor's off-current. This can sometimes happen. For this reason, alkali metal or alkali in oxide semiconductor film 307 It is preferable to reduce the concentration of earth metals.

[0178] Furthermore, if nitrogen is present in the oxide semiconductor film 307, electrons, which act as carriers, are generated, Carrier density increases, making it easier to create an n-type semiconductor. As a result, oxide semiconductors containing nitrogen are used. Transistors made with this oxide semiconductor film tend to exhibit normally-on characteristics. Therefore, Furthermore, it is preferable that nitrogen is reduced as much as possible, for example, by secondary ion mass spectrometry. The nitrogen concentration obtained by this method is 5 × 10 18 atoms / cm 3 The following is preferable .

[0179] Note that in the transistor 112 shown in Figure 9(A), the conductive film 304 functions as the gate. Located on the side, between the oxide semiconductor film 307 and the insulating film 314, which serve as the main carrier migration path. An oxide semiconductor film 309 is provided therein. This provides insulation between the oxide semiconductor film 309 and the other part. Even if trap levels are formed between the films 314 due to impurities and defects, the trap levels There is a gap between the P level and the oxide semiconductor film 307. As a result, the oxide semiconductor film 30 Electrons flowing through 7 are less likely to be trapped at the trap level, increasing the on-current of transistor 112. It is possible to do this, and it is also possible to increase the field effect mobility. When an electron is captured in an energy level, that electron becomes a negative fixed charge. As a result, The threshold voltage of the transistor 112 fluctuates. However, the oxide semiconductor film 30 Because there is a gap between level 7 and the trap level, electron trapping at the trap level is reduced. This makes it possible to reduce fluctuations in the threshold voltage.

[0180] Furthermore, the oxide semiconductor film 307 and the oxide semiconductor film 309 are not simply stacked layers. No continuous junction (here in particular, a structure in which the energy at the lower end of the conduction band changes continuously between each film) The film is fabricated so that trap centers and recombination centers are formed at the interface of each film. A layered structure is formed so that no impurities that would form such defect levels are present. Impurities are present between the stacked oxide semiconductor films 307 and 309. Then, the continuity of the energy band is lost, and carriers are trapped or reconnected at the interface. They combine and disappear.

[0181] 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 for the oxide semiconductor film To remove impurities such as water as much as possible, an adsorption-type vacuum pump such as a cryopump is used. Using a pump to perform 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. .

[0182] Here, regarding the band structure of the stacked structure contained in transistor 112, see Figure 9(B). I will use it to explain.

[0183] Figure 9(B) schematically shows a portion of the band structure contained in transistor 112. Here, we will discuss the case where silicon oxide layers are provided as insulating film 306 and insulating film 314. Let me explain. Note that EcI1 shown in Figure 9(B) is the silicon oxide layer used as the insulating film 306. This shows the energy at the lower end of the conduction band, and EcS1 is the energy at the lower end of the conduction band of the oxide semiconductor film 307. EcS2 indicates the energy of the lower end of the conduction band of the oxide semiconductor film 309, and Ec I2 represents the energy at the lower end of the conduction band of the silicon oxide layer used as the insulating film 314.

[0184] As shown in Figure 9(B), in oxide semiconductor film 307 and oxide semiconductor film 309, The energy at the lower end of the conduction band changes smoothly because there is no barrier. In other words, it changes continuously. It can also be said that this is because oxide semiconductor film 307 and oxide semiconductor film 309 are common. The elements are present, and oxygen is transferred between the oxide semiconductor film 307 and the oxide semiconductor film 309. This can be attributed to the formation of a mixed layer through movement.

[0185] From Figure 9(B), in the oxide semiconductor film 308, the oxide semiconductor film 307 is a well. ) and in a transistor using oxide semiconductor film 308, the channel formation region is acid It can be seen that it is formed on the oxide semiconductor film 307. Note that the oxide semiconductor film 308 is the conduction band. Because the energy at the lower end is continuously changing, the oxide semiconductor film 307 and the oxide semiconductor film It could also be said that it is continuously connected to 309.

[0186] Furthermore, as shown in Figure 9(B), near the interface between the oxide semiconductor film 309 and the insulating film 314 This includes impurities and defects in silicon or carbon, which are constituent elements of the insulating film 314. Although a lapp level may be formed, the provision of the oxide semiconductor film 309 prevents oxidation. The semiconductor film 307 and the trap level can be kept apart. However, EcS1 and Ec When the energy difference with S2 is small, electrons in the oxide semiconductor film 307 exceed the energy difference. Sometimes, it reaches the trap level. When electrons are trapped at the trap level, the insulating film... A negative fixed charge is generated at the interface, and the transistor's threshold voltage shifts in the positive direction. Therefore, the energy difference between EcS1 and EcS2 is preferably 0.1 eV or more. Setting it to 0.15eV or higher reduces the fluctuation in the transistor's threshold voltage, making it more stable. This is preferable because it results in the desired electrical characteristics.

[0187] The oxide semiconductor described above is used in a transistor of a liquid crystal display device according to one aspect of the present invention. By being present, the image display in the pixel area continues even after the writing of the image signal to the pixel area has stopped. This can be maintained. In addition, the transistor can supply voltage to the liquid crystal elements of the pixels. By using it as an element to control the power supply, the period during which the voltage supply to the liquid crystal element is maintained. This allows for a longer period of time to be secured.

[0188] The configurations and methods described in this embodiment are similar to those described in other embodiments. They can be used in combination as appropriate.

[0189] (Embodiment 3) In this embodiment, an example of the pixel configuration of a liquid crystal display device according to one aspect of the present invention is described. Regarding an example that differs from the top view and cross-sectional view of pixel 100 shown in Figures 5 and 6 of the first form of implementation, The explanation will be given using Figures 10 and 11.

[0190] Figure 10 shows an example of a top view of pixel 100 shown in Figure 1(A). Note that in Figure 10, the pixels To clarify the top view of the 100, some components such as the gate insulating film have been omitted from the illustration. Furthermore, the cuts between the dashed lines A1-A2 and A3-A4 shown in Figure 10 are also shown. Figure 11 shows a cross-sectional view corresponding to a surface.

[0191] The pixels 100 shown in Figures 10 and 11 are on a substrate 302 having an insulating surface, and a transistor A conductive film 304 is provided which has the function of a gate for TA 112 and the function of a wiring GL. Furthermore, the substrate 302 has the function of being an electrode for the capacitive element 113 and the first common An electrode 354, which functions as an electrode, is provided.

[0192] Furthermore, an insulating film 306 is provided on the substrate 302 so as to cover the conductive film 304. Then, with the insulating film 306 in between, the transistor 112 is positioned where it overlaps with the conductive film 304. An oxide semiconductor film 308 that functions as a channel-forming region is provided. Conductive films 310 and 312 are provided on film 308. A conductive film 313 formed in the same process is provided on the electrode 354 and the insulating film 306. . The conductive film 310 functions as a wiring SL and as the source or drain of transistor 112. It has the function of being the source or drain of transistor 112. The conductive film 312 is the source or drain of transistor 112. It has the function of a capacitance line. The conductive film 313 has the function of a capacitance line.

[0193] Furthermore, electrode 354 is formed in the same process as oxide semiconductor film 308. 4 is a conductive oxide semiconductor with higher conductivity than oxide semiconductor film 308. Electrode 3 54 is provided in contact with the insulating film 321, and hydrogen contained in the insulating film 321 is deposited into electrode 3 By diffusing into 54, the conductivity increases. Also, contact with the conductive film 313 of electrode 354. Since the region is not in contact with the insulating film 314, the oxygen vacancies in the oxide semiconductor are not filled. Therefore, conductivity increases. Consequently, electrode 354 is processed in the same way as oxide semiconductor film 308. Even oxide semiconductor films formed using this method can function as electrodes.

[0194] Furthermore, an insulating film 314 covers the oxide semiconductor film 308 and the conductive films 310 and 312. It is provided. In addition, the insulating film 314 is located at one end of the electrode 354 and the conductive film 313. It is provided so as to cover one end. In addition, the insulating film 314 is a part of the electrode 354 and It has an opening 364 in which a portion of the conductive film 313 is exposed.

[0195] Furthermore, an insulating film 321 is provided on the insulating film 314, the electrode 354, and the conductive film 313. Furthermore, the insulating films 314 and 321 are provided with openings 366 that reach the conductive film 312. Furthermore, a pixel electrode 322 is provided on the insulating film 321, and the pixel electrode 32 2 is connected to the conductive film 312 via the opening 366. Also, the pixel electrode 322 is the first It is positioned to overlap with electrode 354, which functions as a common electrode, as shown in the top view of Figure 10. It has an opening (slit). Also, on the insulating film 321 and the pixel electrode 322 An alignment film 324 is provided.

[0196] Furthermore, a substrate 330 is provided so as to face the substrate 302. Below the substrate 330 It includes a light-shielding film 332 that has the function of blocking visible light, and a material that transmits visible light in a specific wavelength range. A color film 334, an insulating film 336 in contact with the light-shielding film 332 and the colored film 334, and the insulating film 336 A second common electrode 338 that is in contact with the second common electrode 338 and an alignment film 340 that is in contact with the second common electrode 338 are provided. It is being done.

[0197] Then, between substrate 302 and substrate 330, it is sandwiched between alignment films 324 and 340. Furthermore, a liquid crystal layer 350 containing liquid crystal material is provided. Electrode 354, insulating film 321, pixel electrode 322, and second common electrode 3, all functioning as electrodes. The liquid crystal element 111 is composed of 38. The liquid crystal layer 350 is a negative type liquid crystal. Using the material, the resistivity of the liquid crystal material is 1.0 × 10 13 Ω cm or more 1.0×10 16 Ω It is less than 1 cm.

[0198] In the configuration of the pixel 100 shown in this embodiment, an insulating film that functions as a planarization film is used. In addition, the electrode 354, which functions as the first common electrode, is made in the same process as the oxide semiconductor film 308. A point is formed in a certain manner, and a conductive film 313 that functions as a capacitance line is provided in contact with the electrode 354. This aspect differs significantly from the configuration shown in Figures 5 and 6 of the previous embodiment 1.

[0199] In this way, by not using a planarization film, impurities contained in the planarization film (for example, water) can be removed. This can suppress the penetration of substances such as into the oxide semiconductor film 308. Therefore, oxidation Because the reliability of the transistor 112 using the monocrystalline semiconductor film 308 is improved, the display quality is high. It can be used as a liquid crystal display device.

[0200] Next, an example of a pixel fabrication method shown in Figure 11 will be explained using Figures 12 and 13. To do so.

[0201] As shown in Figure 12(A), after forming a conductive film on the substrate 302, the conductive film is etched. A conductive film 304 is formed by processing the shape using a tool or the like. Next, an insulating film is applied to the conductive film 304. A border film 306 is formed. Next, an oxide semiconductor film is formed on the insulating film 306, and then the oxide The semiconductor film is shaped by etching or other means, and separated into island-like structures at positions overlapping with the conductive film 304. The oxide semiconductor film 308 is separated from the oxide semiconductor film 308, and the oxide semiconductor film 352 is separated from the oxide semiconductor film 308. It forms.

[0202] The substrate 302, conductive film 304, insulating film 306, and oxide semiconductor film 308 are as follows: The substrate 302, conductive film 304, insulating film 306, and oxide semiconductor described in Embodiment 1, respectively. The film 308 can be formed by using materials and methods that can be used for film 308. Furthermore, the oxide semiconductor film 352 is made of the same materials and manufactured using the same method as the oxide semiconductor film 308. It can be formed more effectively.

[0203] Next, as shown in Figure 12(B), on the insulating film 306 and the oxide semiconductor films 308 and 352 After forming a conductive film, the shape of the conductive film is processed by etching or the like, Conductive films 310 and 312 in contact with the oxide semiconductor film 308, and conductive films in contact with the oxide semiconductor film 352 An electrical film 313 is formed.

[0204] The conductive films 310, 312, and 313 are as follows: conductive films 310, 312 as described in Embodiment 1. , can be formed by using materials and manufacturing methods that can be used in 313. .

[0205] Next, as shown in Figure 12(C), insulating film 306, oxide semiconductor films 308, 352, and An insulating film 314 is formed on the conductive films 310, 312, and 313.

[0206] The insulating film 314 is a material that can be used as the insulating film 314 described in Embodiment 1. It can be formed by using the and manufacturing methods.

[0207] Next, as shown in Figure 12(D), the insulating film 314 is shaped by etching or the like. The opening 364 is formed so that a portion of the oxide semiconductor film 352 and a portion of the conductive film 313 are exposed. This is achieved. Furthermore, it is sufficient that at least the oxide semiconductor film 352 is exposed at the opening 364. The surface of the conductive film 313 does not need to be exposed.

[0208] Methods for forming the opening 364 include, for example, dry etching or wet etching. The etching method is used. In addition, the dry etching method and the wet etching method are combined to create openings. Part 364 may be formed.

[0209] Next, as shown in Figure 13(A), insulating film 314 and opening 364 are insulated A film 321 is formed.

[0210] The insulating film 321 is protected from external impurities, such as water, alkali metals, alkaline earth metals, etc. However, it is a film formed of a material that prevents diffusion into the oxide semiconductor, and furthermore, it contains hydrogen. Therefore, when hydrogen from the insulating film 321 diffuses into the oxide semiconductor film 352, the oxide semiconductor film 35 In 2, hydrogen combines with oxygen, or hydrogen combines with an oxygen vacancy and the electron carrier It is generated. As a result, the oxide semiconductor film 352 has higher conductivity than the oxide semiconductor film 308. It becomes higher and functions as the first common electrode, electrode 354.

[0211] For example, the insulating film 321 is a silicon nitride film with a thickness of 50 nm or more and 400 nm or less. Alternatively, a silicon nitride film or the like can be used. In this embodiment, insulating film 32 As example 1, a silicon nitride film with a thickness of 100 nm is used.

[0212] Furthermore, the silicon nitride film is preferably deposited at a high temperature to enhance its blocking properties. For example, the substrate temperature should be 100°C or higher and below the substrate's strain point, more preferably 300°C or higher. It is preferable to form the film by heating at a temperature of 0°C or lower. However, when forming the film at high temperatures, acid Oxygen may be released from the ionized semiconductor film 308, causing an increase in carrier concentration. Therefore, the temperature should be set so that this phenomenon does not occur.

[0213] Furthermore, although not shown in Figures 11 and 13, after forming the insulating film 321, An insulating film may be formed further. As the insulating film, for example, P using organic silane gas may be used. A silicon oxide film formed by the E-CVD method can be used. It can be provided in the range of 300 nm to 600 nm. As for organic silane gas, silicic acid Ethyl (TEOS: chemical formula Si(OC2H5)4), tetramethylsilane (TMS: chemical formula) Formula Si(CH3)4), tetramethylcyclotetrasiloxane (TMCTS), octamethasone Tylcyclotetrasiloxane (OMCTS), hexamethyldisilazane (HMDS), Riethoxysilane (SiH(OC2H5)3), Trisdimethylaminosilane (SiH( Silicon-containing compounds such as N(CH3)2)3) can be used. Also, the above oxidation For example, the silicon film is prepared using organic silane gas and oxygen, with the substrate temperature set to between 200°C and 550°C. Preferably, the temperature is between 220°C and 500°C, and more preferably between 300°C and 450°C. It can be formed by the PE-CVD method.

[0214] By forming the aforementioned insulating film on the insulating film 321, the transistor and the like can be formed. It becomes possible to flatten the resulting irregularities. Furthermore, the insulating film described above is formed from an inorganic material. Therefore, compared to planarized resin films using organic materials, it has an effect on oxide semiconductor films. It contains few impurities.

[0215] Next, after forming at least an insulating film 314, a heat treatment is performed, and the insulating film 314 contains The oxygen is transferred to the oxide semiconductor film 308, filling the oxygen vacancies in the oxide semiconductor film 308. It is preferable.

[0216] Next, as shown in Figure 13(B), the desired regions of the insulating films 314 and 321 are removed. Then, an opening 366 that reaches the conductive film 312 is formed.

[0217] Methods for forming the opening 366 include, for example, dry etching or wet etching. The etching method is used. In addition, the dry etching method and the wet etching method are combined to create openings. Part 366 may be formed.

[0218] Next, as shown in Figure 13(C), a pixel electrode 322 is formed on the insulating film 321. The pixel electrode 322 is connected to the conductive film 312 via the aperture 366.

[0219] The pixel electrode 322 has a transparent conductive film formed on the insulating film 321, and the transparent film is removed by etching or the like. It is formed by processing the shape of a light-conductive film.

[0220] The pixel electrode 322 can be the same as the pixel electrode 322 described in Embodiment 1. It can be formed by utilizing the materials and manufacturing methods described herein.

[0221] Next, an alignment film 324 is formed on the insulating film 321 and the pixel electrode 322 (not shown). The alignment film 324 can be formed using methods such as rubbing or photo-alignment.

[0222] The structure to be formed on the substrate 302 can be created through the above process.

[0223] The substrate 330, which is provided opposite the substrate 302, and the liquid crystal element 111, etc., are in Embodiment 1 It can be formed by referring to the description.

[0224] The configurations and methods described in this embodiment are similar to those described in other embodiments. They can be used in combination as appropriate.

[0225] (Embodiment 4) In this embodiment, one electronic device using a liquid crystal display device according to one aspect of the present invention An example will be explained using Figure 14.

[0226] A liquid crystal display device according to one aspect of the present invention includes a display device, a personal computer, and a recording medium. Image playback device equipped with (typically DVD: Digital Versatile Di (Used in a device that plays back recording media such as SC and has a display capable of displaying the images.) It is possible. In addition, electronic devices that can use a liquid crystal display device according to one aspect of the present invention The devices include mobile phones, game consoles (including portable ones), personal digital assistants (PDAs), e-books, and video cameras. , cameras such as digital still cameras, goggle-type displays (head-mounted displays) Playback), navigation system, sound playback device (car audio, digital audio) (Optical players, etc.), photocopiers, fax machines, printers, multifunction printers, ATMs Examples include ATMs and vending machines. Figure 1 shows specific examples of these electronic devices. This is shown in 4.

[0227] Figure 14(A) shows a portable game console, consisting of a casing 5001, a casing 5002, and a display unit 5003. Display unit 5004, microphone 5005, speaker 5006, operation key 5007, It has a tyrus 5008, etc. Display unit 5003 or display unit 5004, one embodiment of the present invention A liquid crystal display device related to the above can be used. Note that the portable game console shown in Figure 14(A) It has two display units 5003 and 5004, but a portable game console has The number of display units is not limited to this.

[0228] Figure 14(B) shows a display device, consisting of a housing 5201, a display unit 5202, a support base 5203, etc. It has. A liquid crystal display device according to one aspect of the present invention can be used in the display unit 5202. Furthermore, display devices include all types, such as those for personal computers, TV broadcast reception, and advertising displays. This includes display devices for showing information.

[0229] Figure 14(C) shows a notebook personal computer, consisting of a casing 5401 and a display unit 540 2. It has a keyboard 5403, a pointing device 5404, etc. Display unit 5402 A liquid crystal display device according to one aspect of the present invention can be used.

[0230] Figure 14(D) shows a portable information terminal, consisting of a first housing 5601, a second housing 5602, and a first display. It has a section 5603, a second display section 5604, a connection section 5605, an operation key 5606, etc. The display unit 5603 is located in the first housing 5601, and the second display unit 5604 is located in the second housing 5 It is located at 602. And the first housing 5601 and the second housing 5602 are connected at the connection part 5 They are connected by 605, and the angle between the first housing 5601 and the second housing 5602 is, It can be changed by part 5605. The video in the first display unit 5603 is connected to the connection unit Switch according to the angle between the first housing 5601 and the second housing 5602 in 5605. The configuration is also good. In one aspect of the present invention, the first display unit 5603 or the second display unit 5604 is provided. Such liquid crystal display devices can be used. A liquid crystal display device is used in which at least one of 04 has the function of a position input device added to it. It is also acceptable to do so. Furthermore, the function as a position input device involves a touch panel on the liquid crystal display. It can be added by providing it. Alternatively, the function as a position input device is a photosensor. It is also possible to add a photoelectric conversion element, also known as a photo-converting element, to the pixel portion of a liquid crystal display device. can.

[0231] Figure 14(E) shows a video camera, consisting of a first housing 5801, a second housing 5802, and a display unit 5 It has 803, operation key 5804, lens 5805, connection part 5806, etc. Operation key 58 04 and lens 5805 are provided in the first housing 5801, and the display unit 5803 is in the second housing It is located in body 5802. And the first housing 5801 and the second housing 5802 are connected. They are connected by part 5806, and the angle between the first housing 5801 and the second housing 5802 is, The connection unit 5806 allows for changes. This includes switching the video on the display unit 5803. This is done according to the angle between the first housing 5801 and the second housing 5802 at the connection part 5806. This configuration is also acceptable. The display unit 5803 may use a liquid crystal display device according to one aspect of the present invention. It is possible.

[0232] Figure 14(F) is a mobile phone, and the housing 5901 includes a display unit 5902, a microphone 5907, Speaker 5904, camera 5903, external connection unit 5906, and control buttons 5905 It is provided. A liquid crystal display device according to one aspect of the present invention is used in the circuit of a mobile phone. It is possible to do so. Furthermore, a liquid crystal display device according to one aspect of the present invention is formed on a flexible substrate. In that case, the liquid crystal display device is suitable for the display unit 5902 having a curved surface as shown in Figure 14(F). It is possible to use it.

[0233] The configurations and methods described in this embodiment are similar to those described in other embodiments. They can be used in combination as appropriate. [Examples]

[0234] In this embodiment, the transmittance of a liquid crystal display device, which is one aspect of the present invention, is measured. The liquid crystal display device used in this embodiment will be described below using Figure 15.

[0235] The liquid crystal display device 720 shown in Figure 15(A) is an example of a liquid crystal display device according to one aspect of the present invention. ru.

[0236] The liquid crystal display device 720 shown in Figure 15(A) consists of a substrate 602 and a transistor on the substrate 602 A conductive film 604 that functions as a gate, and an insulating film 60 on the substrate 602 and conductive film 604 6, insulating film 606, and oxide formed at a position overlapping with conductive film 604 on insulating film 606 A monocrystalline semiconductor film 608, conductive films 610 and 612 connected to the oxide semiconductor film 608, and an insulating film. 606, oxide semiconductor film 608, and insulating film 614 formed on conductive films 610, 612 And, the insulating film 616 on the insulating film 614, the first common electrode 618 on the insulating film 616, and insulation The insulating film 620 on the film 614 and the first common electrode 618, and the pixel electrode 62 on the insulating film 620 2, an insulating film 620 and an alignment film 624 on the pixel electrode 622, and a liquid crystal layer 6 on the alignment film 624 50, an alignment film 640 on the liquid crystal layer 650, and a second common electrode 638 on the alignment film 640, The insulating film 636 on the second common electrode 638, and the light-shielding film 632 and the colored film 6 on the insulating film 636 It comprises 34 and a substrate 630 on a light-shielding film 632 and a colored film 634.

[0237] Furthermore, the conductive film 604, the insulating film 606, the oxide semiconductor film 608, and the conductive films 610, 6 12 constitutes transistor 712. Also, transistor 712 has The conductive film 612 is connected to the pixel electrode 6 through openings provided in the insulating film 616 and insulating film 620. It is connected to 22.

[0238] Next, we will explain the comparative liquid crystal display device 730 shown in Figure 15(B).

[0239] The liquid crystal display device 730 shown in Figure 15(B) consists of a substrate 602 and a transistor on the substrate 602 A conductive film 604 that functions as a gate, and an insulating film 60 on the substrate 602 and conductive film 604 6, insulating film 606, and oxide formed at a position overlapping with conductive film 604 on insulating film 606 A monocrystalline semiconductor film 608, conductive films 610 and 612 connected to the oxide semiconductor film 608, and an insulating film. 606, oxide semiconductor film 608, and insulating film 614 formed on conductive films 610, 612 And, the insulating film 616 on the insulating film 614, the first common electrode 618 on the insulating film 616, and insulation The insulating film 620 on the film 614 and the first common electrode 618, and the pixel electrode 62 on the insulating film 620 2, an insulating film 620 and an alignment film 624 on the pixel electrode 622, and a liquid crystal layer 6 on the alignment film 624 50, an alignment film 640 on the liquid crystal layer 650, an insulating film 636 on the alignment film 640, and an insulating film 6 36 consists of a light-shielding film 632 and a colored film 634, and a substrate 63 on the light-shielding film 632 and the colored film 634. It has 0 and an electrode 642 on the substrate 630.

[0240] Furthermore, the conductive film 604, the insulating film 606, the oxide semiconductor film 608, and the conductive films 610, 6 12 constitutes transistor 712. Also, transistor 712 has The conductive film 612 is connected to the pixel electrode 6 through openings provided in the insulating film 616 and insulating film 620. It is connected to 22.

[0241] Furthermore, Figure 15(A) shows a liquid crystal display device 720 according to one embodiment of the present invention, and Figure 15(B) shows The difference from the comparative liquid crystal display device 730 is the second common electrode 638 and electrode 642 More specifically, the liquid crystal display device 720 has a second common electrode located below the substrate 630. 638 is provided, and the liquid crystal display device 730 has an electrode 642 above the substrate 630. It's being kicked.

[0242] In the configuration shown in Figure 15(A), the alignment film 640 is directed by the second common electrode 638. Voltage can be applied to the liquid crystal layer 650 via this. On the other hand, in the configuration shown in Figure 15(B) In this case, since electrode 642 is located above substrate 630, by electrode 642 It is difficult to apply voltage to the liquid crystal layer 650.

[0243] The following describes the manufacturing method of the liquid crystal display devices 720 and 730 shown in Figures 15(A) and (B). The illumination is performed. Note that the liquid crystal display device 720 and the liquid crystal display device 730 have a second common electrode 63 The components other than 8 and electrode 642 are the same. First, let's discuss the method for fabricating the common components. The following explains further.

[0244] A glass substrate was used as the substrate 602. Subsequently, a conductive film 604 was formed on the substrate 602. It was achieved. For the conductive film 604, a tungsten film was formed by sputtering in a 200 nm shape. The process was completed. Subsequently, an insulating film 606 was formed on the substrate 602 and the conductive film 604. Insulating film 60 6. A silicon nitride film with a thickness of 400 nm and a silicon oxide nitride film with a thickness of 50 nm. It was formed by layering.

[0245] Furthermore, the silicon nitride film consists of a first silicon nitride film, a second silicon nitride film, and a third silicon nitride film. A three-layer laminated structure of silicon nitride film was adopted.

[0246] The first silicon nitride film is a silane at a flow rate of 200 sccm, and a silane at a flow rate of 2000 sccm. A plasma CVD apparatus uses nitrogen and ammonia gas at a flow rate of 100 sccm as raw material gases. It is supplied to the processing chamber, the pressure inside the processing chamber is controlled to 100 Pa, and a 27.12 MHz high-frequency electric current is used. Using a power source, 2000W of power was supplied, and the material was formed to a thickness of 50nm. Second For silicon nitride films, silane at a flow rate of 200 sccm, nitrogen at a flow rate of 2000 sccm, And ammonia gas at a flow rate of 2000 sccm is used as the raw material gas for processing in a plasma CVD apparatus. A 27.12 MHz high-frequency power supply is used to supply power to the chamber, control the pressure inside the processing chamber to 100 Pa, and supply power to the chamber. Then, 2000W of power was supplied and it was formed to a thickness of 300nm. Third nitriding As for the silicon membrane, a flow rate of 200 sccm of silane and a flow rate of 5000 sccm of nitrogen were used. It is supplied as a raw material gas to the processing chamber of the plasma CVD apparatus, and the pressure inside the processing chamber is controlled to 100 Pa. It is controlled and supplied with 2000W of power using a 27.12MHz high-frequency power supply, and the thickness is 50 It was formed to have a size of nm. The first silicon nitride film, the second silicon nitride film, and The substrate temperature during the formation of the third silicon nitride film was set to 350°C.

[0247] As for the silicon oxidizride film, a silane flow rate of 20 sccm and a flow rate of 3000 sccm Dinitrogen oxide is supplied as a raw material gas to the processing chamber of the plasma CVD apparatus, and the pressure inside the processing chamber is set to 4 The pressure is controlled to 0 Pa, and 100 W of power is supplied using a 27.12 MHz high-frequency power supply, and the acid A silicon oxide nitride film was formed. The substrate temperature during the formation of the silicon oxide nitride film was 350°C. did.

[0248] Next, an oxide semiconductor film 608 is formed at a position overlapping the conductive film 604 via the insulating film 606. Here, a 35 nm thick oxide semiconductor film was applied to an insulating film 614 using the sputtering method. It was formed.

[0249] Oxide semiconductor films are sputtered using an In:Ga:Zn=1:1:1 (atom) target. The target (numerical ratio) is oxygen at a flow rate of 30 sccm and argon at a flow rate of 270 sccm. It is supplied as a sputtering gas into the processing chamber of the sputtering apparatus, and the pressure inside the processing chamber is set to 0 The film was formed by controlling the pressure to 0.6 Pa and supplying 5 kW of DC power. The substrate temperature during the process was set to 170°C.

[0250] Next, conductive films 610 and 612 were formed in contact with the oxide semiconductor film 608.

[0251] As conductive films 610 and 612, a 400 nm thick layer is applied on a 50 nm thick tungsten film. A luminium film was formed, and a 100 nm thick titanium film was formed on the aluminum film.

[0252] Next, the substrate is moved to a depressurized processing chamber, heated to 350°C, and then placed in the processing chamber. A high-frequency power of 150W is supplied to the upper electrode using a 27.12MHz high-frequency power supply, The oxide semiconductor film 608 was exposed to oxygen plasma generated in a nitrogen oxide atmosphere.

[0253] Next, an insulating film 614 was formed on the oxide semiconductor film 608 and the conductive films 610 and 612. Here, the insulating film 614 is a first oxide insulating film, a second oxide insulating film, and a nitride A three-layer laminated structure of insulating films was formed.

[0254] First, after the oxygen plasma treatment described above, the first oxide insulating film is continuously treated without exposure to the atmosphere. A second oxide insulating film was formed. As the first oxide insulating film, a 50 nm thick oxide nitride film was formed. A silicon film is formed, and a silicon oxide-nitride film with a thickness of 400 nm is used as a second oxide insulating film. It was formed.

[0255] The first oxide insulating film is made of silane at a flow rate of 20 sccm and oxide monoxide at a flow rate of 3000 sccm. Using dinitrogen as the raw material gas, with a processing chamber pressure of 200 Pa, a substrate temperature of 350°C, and 100 W of power. It was formed by a plasma CVD method in which high-frequency power was supplied to parallel plate electrodes.

[0256] The second oxide insulating film is made by applying silane at a flow rate of 160 sccm and monoacid at a flow rate of 4000 sccm. Using dinitrogen dioxide as the raw material gas, with a processing chamber pressure of 200 Pa and a substrate temperature of 220°C, 150 The material was formed by plasma CVD using a method in which 0W of high-frequency power was supplied to parallel plate electrodes. Therefore, it contains more oxygen than satisfactorily satisfying the oxygen composition, and some of the oxygen is released upon heating. It is possible to form a desorbable silicon oxidizride film.

[0257] Next, a heat treatment is performed, and water, nitrogen, and water are removed from the first oxide insulating film and the second oxide insulating film. In addition to removing elements, a portion of the oxygen contained in the second oxide insulating film is removed from the oxide semiconductor film 6 It was supplied to 08. Here, it underwent heat treatment at 350°C for 1 hour in a nitrogen and oxygen atmosphere. Ta.

[0258] Next, a nitride insulating film with a thickness of 100 nm was formed on the second oxide insulating film. The membrane is subjected to silane at a flow rate of 50 sccm, nitrogen at a flow rate of 5000 sccm, and 100 sccc. Using ammonia gas at m as the raw material gas, the pressure in the processing chamber was set to 100 Pa, and the substrate temperature was set to 350°C. The material was formed by a plasma CVD method in which 1000W of high-frequency power was supplied to parallel plate electrodes. .

[0259] Next, an opening was formed in the insulating film 614 that reached the conductive film 612. This opening was then dryer It was formed by the cutting method.

[0260] Next, an insulating film 616 having an opening was formed on the insulating film 614. An acrylic resin, which is an organic resin material, was used. The film thickness of the acrylic resin was 2 μm. Ta.

[0261] Next, a first common electrode 618 was formed on the insulating film 616. Therefore, by sputtering, an indium oxide-tin oxide compound (IT) with a thickness of 100 nm is produced. A conductive film of O-SiO2 was formed. The composition of the target used for the conductive film was In The ratio 2O3:SnO2:SiO2 was set to 85:10:5 [weight%].

[0262] Next, an insulating film 620 was formed on the insulating film 616 and the first common electrode 618. For component 20, a nitride insulating film with a thickness of 300 nm was formed. The nitride insulating film was formed at a flow rate of 50 s. Silane at ccm, nitrogen at a flow rate of 5000 sccm, and ammonia gas at a flow rate of 100 sccm. Using s as the raw material gas, the pressure in the processing chamber was set to 200 Pa, the substrate temperature to 220°C, and a 1000W power supply was used. It was formed by plasma CVD, a method in which high-frequency power was supplied to parallel plate electrodes.

[0263] Next, a pixel electrode 622 was formed on the insulating film 620. The pixel electrode 622 was made of spade An 80 nm thick indium oxide-tin oxide compound (ITO-SiO2) was obtained using the Tarling method. A conductive film was formed. The composition of the target used for the conductive film was as follows: The procedure was the same as in step 8. After this, a heat treatment was performed in a nitrogen atmosphere at 250°C for 1 hour.

[0264] Next, an alignment film 624 was formed on the insulating film 620 and the pixel electrode 622. A polyimide film with a thickness of 60 nm was used. The polyimide film used as the orientation film 624 was The resistivity of the imide film is 4.0 × 10⁻⁶. 15 It was Ω·cm.

[0265] The structure to be formed on the substrate 602 was fabricated through the above process.

[0266] Next, regarding the method for manufacturing the structure formed on the substrate 630 which is provided opposite the substrate 602, I will now explain. The structure formed on the substrate 630 is the liquid crystal shown in Figure 15(A). Display device 720 and liquid crystal display device 730 shown in Figure 15(B) are different. Therefore, In the explanation below, the manufacturing methods for liquid crystal display device 720 and liquid crystal display device 730 are described separately. To clarify, the liquid crystal display device 720 is referred to as sample 1, and the liquid crystal display device 730 as sample 2. Then, we will explain each of them.

[0267] <Method for fabricating the structure formed on the substrate 630 shown in Figure 15(A)> A glass substrate was used as the substrate 630. Next, a shielding device was placed in contact with the substrate 630 to cover a desired area. A light-shielding film 632 was formed. The light-shielding film 632 was formed by spin coating with a thickness of 600 nm. An organic resin film containing black pigment was used.

[0268] Next, a colored film 634 was formed in contact with the substrate 630. As for the colored film 634, spinco A 1.4 μm thick organic resin film containing pigment was used by the 3D method.

[0269] Next, an insulating film 636 was formed in contact with the light-shielding film 632 and the colored film 634. An acrylic resin with a thickness of 1.5 μm was used.

[0270] Next, a second common electrode 638 was formed in contact with the insulating film 636. This involves sputtering a 100 nm thick indium oxide-tin oxide compound (ITO) A conductive film of -SiO2 was formed. The composition of the target used for the conductive film was the first The same procedure was followed for the common electrode 618.

[0271] Next, an alignment film 640 was formed by contacting the second common electrode 638. The same material as the alignment film 624 was used for this.

[0272] Next, the prepared substrate 630 and the previously described substrate 602 are bonded together using the dropper encapsulation method. A liquid crystal material that functions as a liquid crystal layer 650 was injected using this method.

[0273] For the liquid crystal layer 650, the cell gap (distance between alignment film 624 and alignment film 640) is 3. The material was adjusted to 5 μm and used as a negative-type liquid crystal material (Merck KGaA: MLC-3006). I used it.

[0274] Through the above steps, sample 1, which is a liquid crystal display device according to one embodiment of the present invention as shown in Figure 15(A), is prepared. did.

[0275] <Method for fabricating the structure formed on the substrate 630 shown in Figure 15(B)> A glass substrate was used as the substrate 630. Next, a shielding device was placed in contact with the substrate 630 to cover a desired area. A light-shielding film 632 was formed. The light-shielding film 632 was formed by spin coating with a thickness of 600 nm. An organic resin film containing black pigment was used.

[0276] Next, a colored film 634 was formed in contact with the substrate 630. As for the colored film 634, spinco A 1.4 μm thick organic resin film containing pigment was used by the 3D method.

[0277] Next, an insulating film 636 was formed in contact with the light-shielding film 632 and the colored film 634. An acrylic resin with a thickness of 1.5 μm was used.

[0278] Next, the electrode 642 is formed in contact with the substrate 630 on the side where the insulating film 636 is not formed. Electrode 642 was made by sputtering a 100 nm thick indium oxide-acid oxide. A conductive film of a tin compound (ITO-SiO2) was formed. The target used in the conductive film was... The composition of the electrode was the same as that of the first common electrode 618.

[0279] Next, an orientation film 640 was formed in contact with the insulating film 636. The orientation film 640 is an orientation film. The same material as that used for film 624 was employed.

[0280] Next, the prepared substrate 630 and the previously described substrate 602 are bonded together using the dropper encapsulation method. A liquid crystal material that functions as a liquid crystal layer 650 was injected using this method.

[0281] For the liquid crystal layer 650, the cell gap (distance between alignment film 624 and alignment film 640) is 3. The material was adjusted to 5 μm and used as a negative-type liquid crystal material (Merck KGaA: MLC-3006). I used it.

[0282] Following the above steps, sample 2, a comparative liquid crystal display device shown in Figure 15(B), was fabricated.

[0283] Next, the transmittance of the prepared samples 1 and 2 was measured. In this configuration, 0V is applied to the first common electrode 618, 5.5V to the pixel electrode 622, and the second common electrode 0.8V was applied to each of the electrodes 638. Also, the pixel electrode 622 and the second common electrode 63 8. The voltage applied to the second common electrode 638 is performed intermittently, and each time the voltage is applied... The data is rewritten. Also, when measuring the transmittance of sample 2, the first common electrode Apply 0V to electrode 618, 5.5V to pixel electrode 622, and 0.8V to electrode 642. The voltage applied to the pixel electrode 622, the second common electrode 638, and the electrode 642 was This is performed intermittently, and the data is rewritten each time a voltage is applied. Note that sample 1 and The control of rewriting the data for sample 2 is controlled by transistor 712 formed in the liquid crystal display device. Therefore, it will be carried out.

[0284] Figures 16 to 20 show the time-transmittance characteristics of sample 1 and sample 2. In Figures 20 and 20, the horizontal axis represents time (s), and the vertical axis represents transmittance (%). In Figures 16 to 20, the case where the maximum gradation is achieved (transmittance 100%) This is the result of the time-transmittance characteristics (when the conditions are met). Also, Figure 21 shows the time-transmittance characteristics of sample 1. The transient characteristics results are shown. In Figure 21, the horizontal axis represents time (s) and the vertical axis represents transmittance (%). ) are shown respectively. Also, in Figure 21, the case where the intermediate gradation is achieved (transparency) This is the result of the time-transmittance characteristics (when the ratio is set to 50%). Note that the intermediate gradations and In that case, the time-transmittance characteristics may differ from those obtained when the maximum gradation is used.

[0285] See also Figures 16(A), 17(A), 18(A), 19(A), and 20(A). The time-transmittance characteristics shown are the results for sample 1, which is one embodiment of the present invention, as shown in Figure 16(B). Figures 17(B), 18(B), 19(B), and 20(B) show the results of comparative sample 2. It is the result.

[0286] Furthermore, in the time-transmittance characteristics shown in Figures 16(A) and (B), once per second, The data is being rewritten, and in the time-transmittance characteristics shown in Figures 17(A) and (B), The data is rewritten once every 5 seconds, as shown in Figures 18(A) and (B) - In terms of transmittance characteristics, data is rewritten once every 15 seconds, as shown in Figure 19(A In the time-transmittance characteristics shown in (B), the data is rewritten once every 30 seconds. In the time-transmittance characteristics shown in Figures 20(A) and (B), 1 in 60 sec The data is being rewritten multiple times. Note that in graphs with the same data rewriting interval... The data rewriting occurs at different times. Therefore, Figures 16 to 2 In the time-transmittance characteristic shown as 0, the rewriting timing is not the same time.

[0287] Furthermore, in the time-transmittance characteristics shown in Figure 21(A), data is recorded once per second. The filter is being replaced, and in the time-transmittance characteristics shown in Figure 21(B), it is replaced once every 5 seconds. The data is being rewritten, and in the time-transmittance characteristics shown in Figure 21(C), 6 The data is rewritten once every 0 seconds.

[0288] From the results in Figures 16 to 20, sample 1, which is one embodiment of the present invention, shows transmission over time. It can be seen that the rate fluctuates little. On the other hand, for comparison sample 2, the transmittance over time is There is a lot of fluctuation. In particular, when the data rewriting interval is long, for example, as shown in Figure 20(B) 6 When data is rewritten once every 0 seconds, a change in transmittance of 3% or more is observed. In one aspect of the present invention, sample 1 is formed by applying a voltage to the second common electrode 638, resulting in liquid crystal formation. This suggests that the variation in transmittance of layer 650 can be suppressed. On the other hand, for comparison, sample 2 In this case, a second common electrode 638 is not provided, and the electrode 642 located above the substrate 630 has a second common electrode. The same potential as the common electrode 638 is applied. Therefore, from electrode 642 to the liquid crystal layer 65 Since no potential is applied to 0, the fluctuations in the liquid crystal layer 650 cannot be suppressed.

[0289] Furthermore, as shown in Figure 21, sample 1, which is one embodiment of the present invention, has data taken once every 5 seconds. There is a change in transmittance of approximately 2% when the data is rewritten. Depending on the displayed image, this may cause flickering. Because it may be recognized as such, it is better to rewrite the data in less than 5 seconds. This suggests that... [Examples]

[0290] In this embodiment, the transmittance of a liquid crystal display device, which is one aspect of the present invention, is calculated. The configuration of the liquid crystal display used in the calculations of this embodiment will be explained below using Figure 22. conduct.

[0291] The liquid crystal display device used in the calculation shown in Figure 22(A) consists of a substrate 802 and electrodes on the substrate 802. 804a, 804b, 854a, 854b, and electrodes 804a, 804b are covered, and the electrodes An insulating film 814 covers the edges of 854a and 854b, and the insulating film 814 and electrodes 854a and 85 The insulating film 821 on 4b, the insulating film 856 on insulating film 821, and the insulating films 821 and 856 interposed The pixel electrode 822a is positioned to overlap with electrode 854a, and insulating films 821, 85 Pixel electrode 822b is provided in a position that overlaps with electrode 854b via 6, and insulating film 856 and the liquid crystal layer 850 on the pixel electrodes 822a and 822b, and the electrode 838 on the liquid crystal layer 850, The configuration includes a substrate 830 on an electrode 838.

[0292] The configuration of the liquid crystal display used in the calculations shown in Figure 22(A) is shown in Figures 10 and 11. In one aspect of the present invention, the pixels of a liquid crystal display device are simplified and used to simplify calculations. This is the configuration. Specifically, substrate 802 corresponds to substrate 302 shown in Figure 11, and electrode 804a 804b corresponds to the conductive film 304 shown in Figure 11, and electrodes 854a and 854b are shown in Figure 11. The electrode 354 corresponds to the insulating film 814 shown in Figure 11, and the insulating film 82 1 corresponds to the insulating film 321 shown in Figure 11, and the pixel electrodes 822a and 822b are shown in Figure 11. The base electrode 322 corresponds to the liquid crystal layer 850 shown in Figure 11, and electrode 838 This corresponds to the second common electrode 338 shown in Figure 11, and the substrate 830 is the substrate 330 shown in Figure 11. It corresponds to this. Note that the insulating film 856 shown in Figure 22(A) is not shown in Figure 11. stomach.

[0293] Furthermore, the liquid crystal display used in the calculation shown in Figure 22(B) is the same as the one used in the calculation shown in Figure 22(A). The configuration of the liquid crystal display device is such that electrodes 838 are not provided on the liquid crystal layer 850, and The external configuration is the same as that shown in Figure 22(A).

[0294] Note that in the configuration of the liquid crystal display used in the calculations shown in Figures 22(A) and (B), pixel 2 This shows the cross-sectional structure of two electrodes, specifically electrode 804a and electrode 854a, on the left side of the diagram. The side containing the pixel electrode 822a is represented as one pixel, and the right side in the figure, more specifically the electrode The side containing 804b, electrode 854b, and pixel electrode 822b is represented as the other pixel. In Figures 22(A) and (B), the pixel electrodes 822a and 822b are separated. These three electrodes are represented as a single electrode.

[0295] Furthermore, the configuration of the liquid crystal display device used in the calculation shown in Figure 22(A) is designated as Sample 3, and Figure 22(B) Sample 4 is the configuration of the liquid crystal display used in the calculation shown in ( ). Sample 3 is one embodiment of the present invention. The configuration of the liquid crystal display device is as shown, and sample 4 is a configuration of a liquid crystal display device of one embodiment for comparison.

[0296] Furthermore, electrodes 804a and 804b shown in Figures 22(A) and (B) have a thickness of 200 nm and a width of 200 nm. The thickness was set to 2 μm, and electrodes 854a and 854b were set to a thickness of 200 nm and a width of 20 μm. Insulating film 814 is set to have a thickness of 500 nm, and insulating film 821 is set to have a thickness of 100 nm. The insulating film 856 is set to a thickness of 400 nm, and the pixel electrodes 822a and 822b are set to a thickness of 100 nm. The dimensions are set to nm, width = 2 μm, and the liquid crystal layer 850 has a thickness of 4 μm and is made of negative-type liquid crystal material (Merck Co., Ltd.). The electrode was set to (Manufactured by: MLC-3006). Also, the electrode 838 shown in Figure 22(A) has a thickness It was set to =100nm.

[0297] Furthermore, with respect to the liquid crystal display device configuration used in the calculation shown in Figure 22(A), the electrode 804a 0V, 6V at electrode 804b, 0V at electrodes 854a and 854b, 0V at pixel electrode 822a, When 6V is applied to the pixel electrode 822b and 0V is applied to the electrode 838, the liquid crystal layer 8 The transmittance calculation was performed for a value of 50.

[0298] Furthermore, with respect to the liquid crystal display device configuration used in the calculation shown in Figure 22(B), the electrode 804a 0V, 6V at electrode 804b, 0V at electrodes 854a and 854b, 0V at pixel electrode 822a, Calculation of the transmittance of the liquid crystal layer 850 when 6V is applied to each pixel electrode 822b. The above procedure was performed. Note that the settings for each electrode as described above are shown in both Figure 22(A) and (B). The applied voltage when the pixels on the left side of the diagram are assumed to be displayed in black, and the pixels on the right side of the diagram are assumed to be displayed in white. It's oppressive.

[0299] Figure 23 shows the calculation results for transmittance. Note that LCD was used as the calculation software for the transmittance calculation. A Master (manufactured by Shintech) was used.

[0300] In Figure 23, the horizontal axis represents position (μm), and the vertical axis represents transmittance (%). Furthermore, in Figure 23, the solid line represents sample 3, and the dashed line represents sample 4. In Figure 23, electrodes 804a, 804b, 854a, 8 shown in Figures 22(A) and (B) are shown. To indicate the position of 54b, the gray solid lines represent electrodes 804a, 804b, 854a, and 854b. This schematically represents its shape.

[0301] As shown in the calculation results in Figure 23, sample 3, which is configured according to one aspect of the present invention, is located at position 20-30 μ It can be seen that the transmittance is low near m. On the other hand, sample 4, one embodiment for comparison, shows that at positions 20-30 It can be seen that the transmittance is high around μ. This is because sample 3 has a higher liquid crystal layer 850 compared to sample 4. Since the electrode 838 is located on one side, the voltage applied to the electrode 838 (in this embodiment, 0V) This suggests that it suppresses the increase in transmittance around the 20-30μ position. Furthermore, at a position of approximately 40-50 μm, the transmittance of sample 3 is higher than that of sample 4. This can be confirmed. Note that in Figure 23, the pixels on the left, represented by positions 0 to 25 μm, each electrode Since the voltage is set to 0V, a black display, i.e., low transmittance, is desirable. In the rightmost pixel, represented by a depth of 26μm to 55μm, electrodes 804b and 854b each have 6 Since V is applied, a white display, i.e., high transmittance, is desirable. Therefore, this Sample 3, which is a configuration of one aspect of the present invention, has a liquid crystal layer 850 that is different from that of Sample 4, which is a comparative example. Because the configuration has an electrode 838 on one side, calculations have confirmed that it has excellent transmittance characteristics. Done.

[0302] As described above, the liquid crystal display device according to one embodiment of the present invention displays white pixels in adjacent pixels. This suggests that the liquid crystal display device can exhibit excellent contrast between the displayed and black areas. .

[0303] The configuration shown in this embodiment is compatible with the configurations shown in other embodiments or other examples. They can be used in any combination. [Explanation of Symbols]

[0304] 100 pixels 102 transistors 111 Liquid crystal elements 111a Liquid crystal element 111b Liquid crystal element 111c liquid crystal element 112 transistors 113 Capacitive elements 120 circuit boards 122 Common electrode 124 Insulating layer 126 pixel electrodes 130 circuit boards 132 Common electrode 134 liquid crystal layer 230 panels 231 pixel section 232 Drive Circuit 233 Drive Circuit 240 LCD display device 241 Controller 242 Input device 243 CPU 244 Image Processing Circuit 245 Image Memory 246 data 247 Power supply circuit 302 circuit board 304 Conductive film 306 Insulating Film 307 Oxide semiconductor film 308 Oxide semiconductor film 309 Oxide semiconductor film 310 Conductive film 312 Conductive film 313 Conductive film 314 Insulating Film 316 Insulating film 318 Common electrode 320 insulating film 321 Insulating film 322 pixel electrodes 324 alignment film 330 circuit boards 332 Light-shielding film 334 Colored film 336 Insulating Film 338 Common electrode 340 orientation film 350 liquid crystal layers 352 Oxide semiconductor film 354 Electrode 360 Opening 362 Opening 364 openings 366 Opening 602 circuit board 604 Conductive film 606 Insulating film 608 Oxide Semiconductor Film 610 Conductive film 612 Conductive film 614 Insulating film 616 Insulating film 618 Common electrode 620 Insulating film 622 pixel electrodes 624 Alignment film 630 circuit boards 632 Light-shielding film 634 Colored film 636 Insulating film 638 Common electrode 640 orientation film 642 Electrode 650 liquid crystal layers 712 transistors 720 LCD display device 730 LCD display device 802 circuit board 804a electrode 804b electrode 814 Insulating film 821 Insulating film 822a Pixel electrode 822b Pixel electrode 830 circuit board 838 Electrode 850 liquid crystal layers 854a electrode 854b electrode 856 Insulating film 5001 enclosure 5002 enclosure 5003 Display section 5004 Display section 5005 Microphone 5006 Speaker 5007 Operation Keys 5008 Stylus 5201 enclosure 5202 Display section 5203 Support stand 5401 enclosure 5402 Display section 5403 Keyboard 5404 Pointing device 5601 enclosure 5602 enclosure 5603 Display section 5604 Display section 5605 Connection part 5606 Operation Keys 5801 enclosure 5802 enclosure 5803 Display section 5804 Operation Keys 5805 Lens 5806 Connection part 5901 enclosure 5902 Display section 5903 Camera 5904 Speaker 5905 button 5906 External connection section 5907 Mike

Claims

1. A display device having pixels provided with transistors and capacitive elements, The first conductive film has a region that functions as the gate electrode of the transistor, The first insulating film is located on the first conductive film and has a region that functions as a gate insulating film of the transistor, The first oxide semiconductor film is located on the first insulating film and has a channel formation region for the transistor, The device has a second conductive film located on the first oxide semiconductor film and having a region that functions as either the source electrode or the drain electrode of the transistor, A third conductive film is located on the first oxide semiconductor film and has a region that functions as the source electrode or the other of the drain electrode of the transistor. The silicon oxide film has a region in contact with the upper surface of the first oxide semiconductor film and a region overlapping with the channel-forming region, It has a second insulating film having a region in contact with the upper surface of the silicon oxide film, The present invention has a fourth conductive film located on the second insulating film, electrically connected to the second conductive film, and functioning as a pixel electrode, The device has a second oxide semiconductor film located on the first insulating film and functioning as one electrode of the capacitive element, The second insulating film has a first region that is in contact with the upper surface of the second oxide semiconductor film. The second oxide semiconductor film does not overlap with the silicon oxide film in the first region. The fourth conductive film has a region that overlaps with the second oxide semiconductor film via the second insulating film, and functions as the other electrode of the capacitive element. A fifth conductive film is provided, having a region in contact with the upper surface of the second oxide semiconductor film. The silicon oxide film has a region in contact with the first insulating film, The silicon oxide film is a display device having a region that does not overlap with the first oxide semiconductor film and is in contact with the second conductive film or the third conductive film.

2. A display device having pixels provided with transistors and capacitive elements, The first conductive film has a region that functions as the gate electrode of the transistor, The first insulating film has a region that is in contact with the upper surface of the first conductive film and a region that functions as a gate insulating film of the transistor, The first oxide semiconductor film has a region in contact with the upper surface of the first insulating film and has a channel formation region for the transistor, The present invention provides a second conductive film having a region in contact with the upper surface of the first oxide semiconductor film and a region that functions as either the source electrode or the drain electrode of the transistor. A third conductive film has a region that is in contact with the upper surface of the first oxide semiconductor film and has a region that functions as the other of the source electrode or drain electrode of the transistor. The silicon oxide film has a region in contact with the upper surface of the first oxide semiconductor film and a region overlapping with the channel-forming region, It has a second insulating film having a region in contact with the upper surface of the silicon oxide film, A fourth conductive film having a region in contact with the upper surface of the second insulating film, a region in contact with the upper surface of the second conductive film, and functioning as a pixel electrode, The present invention has a second oxide semiconductor film having a region in contact with the upper surface of the first insulating film and functioning as one electrode of the capacitive element, The second insulating film has a first region that is in contact with the upper surface of the second oxide semiconductor film. The second oxide semiconductor film does not overlap with the silicon oxide film in the first region. The fourth conductive film has a region that overlaps with the second oxide semiconductor film via the second insulating film, and functions as the other electrode of the capacitive element. A fifth conductive film is provided, having a region in contact with the upper surface of the second oxide semiconductor film. The silicon oxide film has a region in contact with the first insulating film, The silicon oxide film is a display device having a region that does not overlap with the first oxide semiconductor film and is in contact with the second conductive film or the third conductive film.

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