JP5436926B2 - Semi-permeable membrane - Google Patents

Description

  The present invention relates to a semipermeable membrane, a display device, and a method for manufacturing a pattern substrate.

  Liquid crystal display panels are thin and have low power consumption, making use of OA equipment such as TVs and personal computers, portable information equipment such as mobile phones and electronic notebooks, or car navigation systems and digital displays equipped with liquid crystal monitors. Widely used in cameras.

  A transmissive liquid crystal display panel is often used as a liquid crystal display panel mounted on the display panel. The liquid crystal display panel does not emit light by itself. For this reason, in the transmissive liquid crystal display panel, an illuminating device including a fluorescent tube called a backlight is installed on the back surface or the side thereof. The transmissive liquid crystal display panel displays an image by controlling the amount of light transmitted from the backlight.

  In the transmissive liquid crystal display panel, when the ambient light is very bright, it is difficult to recognize the display because the display light looks darker than the surrounding light.

  Apart from transmissive liquid crystal display panels, reflective liquid crystal display panels have been devised for use in portable information devices and the like that are frequently used outdoors or carried around. In the reflective liquid crystal display panel, a reflective plate is installed in the pixel portion of the substrate. Then, instead of the light from the backlight, display is performed by reflecting external light from the surroundings on the reflecting plate surface. The reflective liquid crystal display panel is disclosed in FIGS. 1 and 2 of Patent Document 1, for example.

  A reflective liquid crystal display panel using reflected light of ambient light has a drawback that visibility is extremely lowered when ambient light is dark.

  In order to solve such problems of the reflective and transmissive liquid crystal display panels, a transflective liquid crystal display panel has been devised. In a transflective liquid crystal display panel, a reflective electrode film that reflects ambient light is partially provided in one pixel electrode together with a transmissive electrode film that transmits light from a backlight. Thereby, both the transmissive display and the reflective display can be realized by one liquid crystal display panel. The transflective liquid crystal display panel is disclosed in FIGS. 1 and 2 of Patent Document 2, for example.

JP-A-6-175126 Japanese Patent Laid-Open No. 11-101992 JP 7-333598 A JP-A-11-281993 JP 2003-50389 A JP 2002-372721 A

In general, ITO in which indium oxide (In ₂ O ₃ ) and tin oxide (SnO ₂ ) are mixed is used for a transparent conductive film generally used in a liquid crystal display panel.

  With the spread of televisions as liquid crystal display devices, it is desired to increase the size of liquid crystal display panels. With this increase in size, the consumption of materials for forming TFTs is increasing. In particular, indium (In), which is a main component of ITO as a conventionally known transparent conductive film, is a rare metal (rare metal). For this reason, if demand grows rapidly in the future, there is a concern about problems such as material shortage or depletion. In addition, there is a concern about the problem of the stable supply of materials due to the significant price increase accompanying these.

  On the other hand, Patent Document 3 discloses a configuration of a transflective liquid crystal display panel having a reflective display function and a transmissive display function by providing a transflective film that reflects and transmits incident light with a certain reflectance and transmittance. Is disclosed. Further, an example is shown in which the transflective film is formed as a laminated film of a transparent conductive film such as an aluminum (Al) metal film or an Al alloy film, or an ITO film and a metal film (paragraph 0044 of Patent Document 3). .

  However, when the transflective film is formed of an Al metal film or an Al alloy film, there is an advantage that it is not necessary to use ITO, but there is a drawback that a display defect is likely to occur. A transflective film such as an Al metal film or an Al alloy film must be a very thin film having a thickness of about 10 nm in order to reflect and transmit. For this reason, if there is a step in the base, the film breaks at that portion, so-called step breakage occurs, and display defects tend to occur.

  In addition, when the transflective film is formed as a laminated film of a transparent conductive film such as an ITO film and a metal film, the film forming process is complicated. Further, when an Al metal film or an Al alloy film is used as the metal film, as described in Patent Documents 4 and 5, ITO and Al are used during processing of an organic alkali developer used in resist patterning in pixel electrode patterning. The battery reaction takes place with the electrode. As a result, there has been a problem that oxidation corrosion of Al and reductive corrosion of ITO occur and cause pattern defects. Furthermore, the formation of an Al oxide layer by interfacial diffusion between Al and ITO during ITO film formation forms an electrical signal blocking layer at the ITO / Al interface, and the electrical resistance value as a pixel electrode is not sufficiently reduced. It was.

  In the case of manufacturing a conventional transflective liquid crystal display panel, Al serving as a reflective electrode is further formed on a liquid crystal display panel having a transmissive electrode or terminal portion made of ITO and patterned. In this case, in order to form at least two kinds of pixel electrode films, that is, an ITO film and an Al film, a film formation chamber having a material source of ITO and Al is necessary. Further, in the pattern processing, each film must be etched using separate chemicals and equipment, and productivity is reduced. As described above, considering the concern about the stable supply of In material, which is the main component of ITO, it is important to develop a process technology that can replace the ITO film.

  In such a limited situation, a technique for replacing the pixel electrode material with AlN instead of ITO is also known. For example, as shown in FIG. 4 of Patent Document 6, an AlN film having specific transmittance and reflectance can be obtained by adjusting the flow ratio of Ar gas and nitrogen gas when forming AlN. Then, a pixel electrode is formed by this AlN film. However, in general, the AlN film itself may exhibit insulating properties, and display defects due to signal delays have been a problem.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a method for producing a semi-permeable film, a display device, and a pattern substrate having improved productivity and good characteristics. To do.

  The translucent film according to the present invention is a translucent film having optical transmission characteristics and reflection characteristics as optical characteristics, and is at least 40 mol% or more and 50 mol% in either aluminum or an alloy containing aluminum as a main component. It is a nitrogen-containing film containing less nitrogen.

  The semi-transmissive film according to the present invention is a semi-transmissive film having optical transmission characteristics and reflection characteristics as optical characteristics, and includes at least nitrogen in either aluminum or an alloy containing aluminum as a main component. This is a laminated film in which a nitrogen-containing film and a metal film of aluminum or an alloy containing aluminum as a main component are alternately laminated.

  A method for producing a patterned substrate according to the present invention is a method for producing a patterned substrate having a semi-transmissive film having light transmission characteristics and reflection characteristics as optical characteristics, and is either aluminum or an alloy containing aluminum as a main component. A step of forming a nitrogen-containing film as the semi-permeable film containing at least 40 mol% or more and less than 50 mol% of nitrogen.

  The pattern substrate manufacturing method according to the present invention is a method of manufacturing a pattern substrate including a semi-transmissive film having light transmission characteristics and reflection characteristics as optical characteristics, and is aluminum or an alloy containing aluminum as a main component. A step of forming a nitrogen-containing film containing at least nitrogen and a step of forming a metal film of either aluminum or an alloy containing aluminum as a main component. The semipermeable membrane is a laminated film in which the nitrogen-containing film and the metal film are alternately laminated.

  ADVANTAGE OF THE INVENTION According to this invention, productivity can improve and the manufacturing method of a semipermeable film, a display device, and a pattern board | substrate with a favorable characteristic can be provided.

FIG. 3 is a plan view showing a configuration of a TFT array substrate according to the first exemplary embodiment. FIG. 3 is a plan view showing a configuration of a main part of the TFT array substrate according to the first embodiment. It is sectional drawing which shows the structure in the AA 'line of FIG. 2, BB' line, and CC 'line. FIG. 3 is a flowchart showing a method for manufacturing the TFT array substrate according to the first embodiment. 4 is a graph showing spectral characteristics of light transmittance and reflectance of the Al-45 mol% N alloy film according to the first embodiment. 6 is a cross-sectional view showing another configuration of the TFT array substrate according to the first exemplary embodiment; FIG. 3 is a graph plotting the light transmittance at a wavelength of 550 nm of an Al—N alloy film in which the film thickness according to the first embodiment is distributed between 10 to 100 nm with respect to the N composition ratio of the film. 4 is a graph showing the N composition ratio dependency of the specific resistance value of the Al—N alloy film measured at a film thickness of 100 nm according to the first embodiment. 3 is a graph showing the N composition ratio dependency of light transmittance and reflectance at a wavelength of 550 nm of the Al—N alloy film according to the first embodiment. FIG. 6 is a cross-sectional view showing a configuration of a TFT array substrate according to a second exemplary embodiment. FIG. 6 is a cross-sectional view illustrating a configuration of a semi-transmissive conductive film of a pixel electrode according to a second embodiment. 6 is a graph showing spectral characteristics of light transmittance and reflectance of the semi-transmissive conductive film according to the second embodiment. 12 is a cross-sectional view showing another configuration of the semi-transmissive conductive film of the pixel electrode according to the second embodiment. FIG. FIG. 6 is a plan view showing a configuration of a TFT array substrate according to a third exemplary embodiment. It is sectional drawing which shows the structure in the AA 'line of FIG. 14, BB' line, and CC 'line.

Embodiment 1
The semipermeable membrane according to the present invention can be used as a pixel electrode of a display device such as a liquid crystal display device or an organic EL display device. For example, it can be used as a pixel electrode of a transflective liquid crystal display device that is a combination of a reflective type and a transmissive type, or a slightly reflective type. First, a TFT array substrate used for a display device will be described with reference to FIG. FIG. 1 is a plan view showing the configuration of the TFT array substrate. Here, an active matrix TFT array substrate used for a transflective liquid crystal display device will be described in detail as an example.

  The TFT array substrate 100 is a TFT substrate in which thin film transistors (TFTs) 108 are arranged in an array. The TFT array substrate 100 is provided with a display area 101 and a frame area 102 provided so as to surround the display area 101. In the display region 101, a plurality of gate lines (scanning signal lines) 3, a plurality of auxiliary capacitance electrodes 5, and a plurality of source lines (display signal lines) 12 are formed.

  The plurality of gate lines 3 and the plurality of auxiliary capacitance electrodes 5 are provided in parallel. The auxiliary capacitance electrode 5 is provided between the adjacent gate lines 3. That is, the gate lines 3 and the auxiliary capacitance electrodes 5 are alternately arranged. The plurality of source lines 12 are provided in parallel. The gate wiring 3 and the source wiring 12 are formed so as to cross each other. Similarly, the auxiliary capacitance electrode 5 and the source line 12 are formed so as to cross each other. Further, the gate wiring 3 and the source wiring 12 are orthogonal to each other. Similarly, the auxiliary capacitance electrode 5 and the source line 12 are orthogonal to each other. A region surrounded by the adjacent gate line 3, auxiliary capacitance electrode 5, and adjacent source line 12 is a pixel 105. In the TFT array substrate 100, the pixels 105 are arranged in a matrix.

  Further, a scanning signal driving circuit 103 and a display signal driving circuit 104 are provided in the frame region 102 of the TFT array substrate 100. The gate line 3 extends from the display area 101 to the frame area 102. The gate wiring 3 is connected to the scanning signal driving circuit 103 at the end of the TFT array substrate 100. Similarly, the source line 12 extends from the display area 101 to the frame area 102. The source line 12 is connected to the display signal drive circuit 104 at the end of the TFT array substrate 100. An external wiring 106 is connected in the vicinity of the scanning signal driving circuit 103. In addition, an external wiring 107 is connected in the vicinity of the display signal driving circuit 104. The external wirings 106 and 107 are wiring boards such as an FPC (Flexible Printed Circuit).

  Various external signals are supplied to the scanning signal driving circuit 103 and the display signal driving circuit 104 via the external wirings 106 and 107. The scanning signal driving circuit 103 supplies a gate signal (scanning signal) to the gate wiring 3 based on a control signal from the outside. The gate lines 3 are sequentially selected by this gate signal. The display signal driving circuit 104 supplies a display signal to the source line 12 based on an external control signal and display data. As a result, a display voltage corresponding to the display data can be supplied to each pixel 105. The scanning signal driving circuit 103 and the display signal driving circuit 104 are not limited to the configuration arranged on the TFT array substrate 100. For example, the drive circuit may be connected by TCP (Tape Carrier Package).

  In the pixel 105, at least one TFT 108 and an auxiliary capacitor 109 are formed. Within the pixel 105, the TFT 108 and the auxiliary capacitor 109 are connected in series. The TFT 108 is disposed near the intersection of the source line 12 and the gate line 3. For example, the TFT 108 serves as a switching element for supplying a display voltage to the pixel electrode. The gate electrode of the TFT 108 is connected to the gate wiring 3, and the ON / OFF of the TFT 108 is controlled by a gate signal input from the gate terminal. The source electrode of the TFT 108 is connected to the source wiring 12. When a voltage is applied to the gate electrode and the TFT 108 is turned on, a current flows from the source wiring 12. Thereby, a display voltage is applied from the source line 12 to the pixel electrode connected to the drain electrode of the TFT 108. An electric field corresponding to the display voltage is generated between the pixel electrode and the counter electrode.

  On the other hand, the auxiliary capacitor 109 is electrically connected not only to the TFT 108 but also to the counter electrode via the auxiliary capacitor electrode 5. Therefore, the auxiliary capacitor 109 is connected in parallel with the capacitor between the pixel electrode and the counter electrode. The voltage applied to the pixel electrode by the auxiliary capacitor 109 can be held for a certain time. An alignment film (not shown) is formed on the surface of the TFT array substrate 100. The TFT array substrate 100 is configured as described above.

  Further, in the case of a liquid crystal display device, a counter substrate is disposed facing the TFT array substrate 100. The counter substrate is, for example, a color filter substrate, and is disposed on the viewing side. On the counter substrate, a color filter, a black matrix (BM), a counter electrode, an alignment film, and the like are formed. For example, in the case of an IPS liquid crystal display device, the counter electrode is disposed on the TFT array substrate 100 side. The TFT array substrate 100 and the counter substrate are bonded to each other through a certain gap (cell gap). Then, liquid crystal is injected and sealed in this gap. That is, the liquid crystal layer is sandwiched between the TFT array substrate 100 and the counter substrate. Furthermore, a polarizing plate, a retardation plate, and the like are provided on the outer surfaces of the TFT array substrate 100 and the counter substrate. Also, a backlight unit or the like is disposed on the non-viewing side of the liquid crystal display panel configured as described above. And it is a semiconductor device, Comprising: The liquid crystal display device which is an optical display apparatus for a display use is comprised.

  The liquid crystal is driven by the electric field between the pixel electrode and the counter electrode. That is, the alignment direction of the liquid crystal between the substrates changes. As a result, the polarization state of the light passing through the liquid crystal layer changes. That is, the polarization state of light that has been linearly polarized after passing through the polarizing plate is changed by the liquid crystal layer. Specifically, light from the backlight unit or external light incident from the outside is linearly polarized by the polarizing plate on the TFT array substrate 100 side. Then, the polarization state changes as this linearly polarized light passes through the liquid crystal layer.

  Therefore, the amount of light passing through the polarizing plate on the counter substrate side changes depending on the polarization state. That is, among the transmitted light that passes through the liquid crystal display panel from the backlight unit, the amount of light that passes through the viewing-side polarizing plate changes. Further, among the reflected light that is incident from the viewing side of the liquid crystal display panel and is reflected by the pixel electrode, the amount of light that passes through the viewing-side polarizing plate changes. The alignment direction of the liquid crystal changes depending on the applied display voltage. Therefore, the amount of light passing through the viewing-side polarizing plate can be changed by controlling the display voltage. That is, a desired image can be displayed by changing the display voltage for each pixel. In this series of operations, the auxiliary capacitor 109 contributes to the maintenance of the display voltage by forming an electric field in parallel with the electric field between the pixel electrode and the counter electrode.

  Next, the configuration of the main part of the TFT array substrate 100 will be described with reference to FIGS. FIG. 2 is a plan view showing a configuration of a main part of the TFT array substrate 100 according to the first embodiment. FIG. 3 is a cross-sectional view showing a configuration taken along line AA ′, line BB ′, and line CC ′ of FIG. Here, the AA ′ line indicates the configuration of the pixel 105, the BB ′ line indicates the configuration of the source terminal portion, and the CC ′ line indicates the configuration of the gate terminal portion. Note that FIG. 3 illustrates the configuration of the gate terminal portion, the source terminal portion, and the pixel 105 in order from the left.

  On the TFT array substrate 100, the gate wiring 3, the source wiring 12, and the auxiliary capacitance electrode 5 are formed. In FIG. 2, the gate wiring 3 is formed in the horizontal direction, and the source wiring 12 is formed in the vertical direction. Further, the auxiliary capacitance electrode 5 is formed in parallel with the gate wiring 3. A part of the auxiliary capacitance electrode 5 extends along the source line 12. A rectangular region surrounded by the gate wiring 3, the auxiliary capacitance electrode 5, and the two source wirings 12 is a pixel 105.

  As shown in FIG. 3, the gate electrode 2, the gate wiring 3, the gate terminal 4, and the auxiliary capacitance electrode 5 are formed on the insulating substrate 1. As the insulating substrate 1, a transparent insulating substrate made of glass, plastic or the like can be used. The gate electrode 2, the gate wiring 3, and the gate terminal 4 are integrally formed. A gate terminal 4 is formed at the end of the gate wiring 3. The gate terminal 4 is connected to the scanning signal driving circuit 103 shown in FIG. 1 and receives a scanning signal.

  Then, a gate insulating film 6 is formed so as to cover the gate electrode 2, the gate wiring 3, the gate terminal 4, and the auxiliary capacitance electrode 5. A semiconductor film 7 is formed on the gate insulating film 6. The gate electrode 2 and the semiconductor film 7 are disposed to face each other with the gate insulating film 6 interposed therebetween. That is, as shown in FIG. 2, the semiconductor film 7 is formed in the vicinity of the gate electrode 2.

  An ohmic contact film 8 is formed on the semiconductor film 7. Impurities are introduced into the ohmic contact film 8 and the resistance is reduced as compared with the semiconductor film 7. The ohmic contact film 8 is not formed in the central portion on the gate electrode 2. The semiconductor film 7 in a region where the ohmic contact film 8 is not formed is a channel region 11.

  The ohmic contact film 8 is formed at both ends of the semiconductor film 7. The ohmic contact film 8 on the auxiliary capacitance electrode 5 side forms a drain region, and the ohmic contact film 8 on the side opposite to the auxiliary capacitance electrode 5 forms a source region. Here, the channel region 11 indicates a region where a channel is formed when a gate voltage is applied to the gate electrode 2. Thus, when a gate voltage is applied to the gate electrode 2, a channel is formed near the interface with the gate insulating film 6 in the channel region 11. When a gate voltage is applied with a predetermined voltage applied between the source region and the drain region, a drain current corresponding to the gate voltage flows between the source region and the drain region.

  A source electrode 9 and a drain electrode 10 are formed on the ohmic contact film 8. A source electrode 9 is formed on the source region. The source region and the source electrode 9 are in direct contact. The source electrode 9 is formed integrally with the source wiring 12 and the source terminal 13. A source terminal 13 is formed at the end of the source wiring 12. The source terminal 13 is connected to the display signal drive circuit 104 shown in FIG. 1 and receives a display signal (video signal). Further, the source wiring 12 and the source terminal 13 other than the TFT 108 are formed on the gate insulating film 6.

  A drain electrode 10 is formed on the drain region. The drain region and the drain electrode 10 are in direct contact. The drain electrode 10 is formed so as to protrude from the gate electrode 2 toward the auxiliary capacitance electrode 5 side. The TFT 108 includes a gate electrode 2, a gate insulating film 6, a semiconductor film 7, an ohmic contact film 8, a source electrode 9, a drain electrode 10, and the like.

  An interlayer insulating film 14 is formed on the source electrode 9, the drain electrode 10, the source wiring 12, and the source terminal 13. The interlayer insulating film 14 is formed so as to cover the entire substrate including the channel region 11. A pixel drain contact hole 15 is formed in the interlayer insulating film 14 on the drain electrode 10. That is, the pixel drain contact hole 15 is formed so as to reach the drain electrode 10. A gate terminal contact hole 16 is formed in the gate insulating film 6 and the interlayer insulating film 14 on the gate terminal 4. That is, the gate terminal contact hole 16 is formed to reach the gate terminal 4. Further, a source terminal contact hole 17 is formed in the interlayer insulating film 14 on the source terminal 13. That is, the source terminal contact hole 17 is formed so as to reach the source terminal 13.

  A pixel electrode 18, a gate terminal pad 19, and a source terminal pad 20 are formed on the interlayer insulating film 14. The pixel electrode 18, the gate terminal pad 19, and the source terminal pad 20 are formed from a single-layer translucent conductive film. The semi-transmissive conductive film is a semi-transmissive film having light transmission characteristics and reflection characteristics as optical characteristics. That is, the semi-transmissive conductive film is a semi-transmissive film that transmits part of light incident on the semi-transmissive conductive film and reflects other light. Accordingly, the pixel electrode 18 becomes a transflective pixel electrode, and a transflective liquid crystal display panel can be configured. Specifically, the semi-transmissive conductive film is an Al-45 mol% N (= Al-45 at% N) alloy film. The Al-45 mol% N alloy film is an Al-N alloy film to which nitrogen (N) is added at a composition ratio of 45 mol%. In other words, the semipermeable conductive film is a nitrogen-containing film.

  The pixel electrode 18 is formed on substantially the entire pixel 105. The pixel electrode 18 is formed so as to overlap at least the drain electrode 10 and the auxiliary capacitance electrode 5. The pixel electrode 18 and the auxiliary capacitor electrode 5 overlap with each other via the gate insulating film 6 and the interlayer insulating film 14. As a result, the auxiliary capacitor 109 that holds the voltage applied to the pixel electrode 18 for a certain period of time is configured. The pixel electrode 18 is embedded in the pixel drain contact hole 15. Thereby, the pixel electrode 18 and the drain electrode 10 are electrically connected via the pixel drain contact hole 15.

  As shown in FIG. 2, the gate terminal pad 19 is formed in, for example, a rectangular shape that is slightly larger than the rectangular gate terminal contact hole 16. A gate terminal contact hole 16 is formed inside the gate terminal pad 19. The source terminal pad 20 and the source terminal portion contact hole 17 are similarly configured.

  As shown in FIG. 3, the gate terminal pad 19 is formed on the gate terminal 4. The gate terminal pad 19 is embedded in the gate terminal contact hole 16. Thereby, the gate terminal 4 and the gate terminal pad 19 are connected through the gate terminal contact hole 16. The source terminal pad 20 is formed on the source terminal 13. The source terminal pad 20 is embedded in the source terminal portion contact hole 17. Thereby, the source terminal 13 and the source terminal pad 20 are electrically connected via the source terminal portion contact hole 17. The TFT array substrate 100 is configured as described above.

  In the first embodiment, a single-layer Al-45 mol% N alloy film having both light semi-transmissive characteristics and electrical conductivity is used as the semi-transmissive conductive film. In general, the Al—N alloy film exhibits insulating properties, whereas the Al-45 mol% N alloy film used in Embodiment 1 has electrical conductivity. Thus, the display characteristics are improved by using the Al-45 mol% N alloy film having good characteristics as the pixel electrode 18 of the transflective liquid crystal display device or the like.

  Moreover, it is not necessary to use ITO which is a conventionally well-known transparent conductive film for the semi-permeable conductive film concerning this Embodiment 1. FIG. That is, it is not necessary to use the rare metal In, and problems such as a shortage or depletion of materials, a problem of a stable supply of materials, and the like are less likely to occur due to a substantial increase in price associated with these.

  Next, a manufacturing method of the TFT array substrate 100 will be described with reference to FIG. FIG. 4 is a flowchart showing a method for manufacturing the TFT array substrate 100.

  First, the process A shown in FIG. 4 is performed. Specifically, first, the insulating substrate 1 such as a glass substrate is cleaned using a cleaning liquid or pure water (a). Then, a first metal thin film is formed on the insulating substrate 1 (b). As the first metal thin film, for example, a metal film made of Cr, Mo, Ti, Al, Cu, an alloy obtained by adding a small amount of other substances to these, or the like is formed.

  Then, a photoresist, which is a photosensitive resin, is applied onto the first metal thin film by spin coating, and a first photolithography process is performed in which the applied photoresist is exposed and developed (c). As a result, the photoresist is patterned into a desired shape. Thereafter, using the photoresist pattern as a mask, the first metal thin film is wet-etched and patterned into a desired shape (d). Thereby, a pattern of the first metal thin film is obtained. Thereafter, removal of the photoresist pattern and cleaning with pure water are performed (e). Through the above steps, the gate electrode 2, the gate wiring 3, the gate terminal 4, and the auxiliary capacitance electrode 5 are formed simultaneously.

  As a preferred embodiment, first, an AlNi alloy film is formed to a thickness of about 200 nm as a first metal thin film by sputtering using known argon (Ar) gas or krypton (Kr) gas. As a target, an AlNi alloy target containing 2 mol% of Ni is used. Further, sputtering is performed using a DC magnetron sputtering apparatus. Next, a photoresist pattern is formed in the first photolithography process. Next, the AlNi alloy film is wet-etched using a known chemical solution composed of phosphoric acid + nitric acid + acetic acid. Thereafter, the photoresist pattern is removed, and the gate electrode 2, the gate wiring 3, the gate terminal 4, and the auxiliary capacitance electrode 5 are formed.

  Next, step B shown in FIG. 4 is performed. First, a gate insulating film 6, a semiconductor film 7, and an ohmic contact film 8 are sequentially formed so as to cover the gate electrode 2, the gate wiring 3, the gate terminal 4, and the auxiliary capacitance electrode 5 (f). Then, a photoresist pattern for patterning the semiconductor film 7 and the ohmic contact film 8 is formed on the ohmic contact film 8 by the second photolithography process (g). Using the photoresist pattern as a mask, the semiconductor film 7 and the ohmic contact film 8 are dry-etched and patterned (h). Then, the photoresist pattern is removed and pure water cleaning is performed (i). Through the above steps, a semiconductor layer including the semiconductor film 7 and the ohmic contact film 8 is formed as a semiconductor pattern.

As a preferred embodiment, a chemical vapor deposition (CVD) method is used here, and film formation is performed under a substrate heating condition of about 300 ° C. Then, a silicon nitride (SiN) film is 400 nm as the gate insulating film 6, an amorphous silicon (a-Si) film is 150 nm as the semiconductor film 7, and phosphorus (P) is added as an impurity as the ohmic contact film 8 (n-type amorphous silicon ( n ⁺ a-Si) films are sequentially formed to a thickness of 50 nm. Next, a photoresist pattern is formed in the second photolithography process. Then, the semiconductor film 7 and the ohmic contact film 8 are dry etched using a known fluorine-based gas. Thereafter, the photoresist pattern is removed, and a semiconductor layer which is a constituent element of the TFT 108 is formed. That is, an island-shaped semiconductor pattern in which the semiconductor film 7 and the ohmic contact film 8 are sequentially stacked is formed.

  Next, step C shown in FIG. 4 is performed. First, a second metal thin film is formed on the ohmic contact film 8 (j). Then, a photoresist pattern is formed on the second metal thin film by the third photolithography process (k). Thereafter, using the photoresist pattern as a mask, the second metal thin film is wet-etched and patterned (l). Thereby, the source electrode 9, the drain electrode 10, the source wiring 12, and the source terminal 13 are formed simultaneously.

  Next, using these electrodes as a mask, dry etching is performed on the ohmic contact film 8 in a region sandwiched between the source electrode 9 and the drain electrode 10 (m). Thereby, the channel region 11 of the TFT 108 is formed. Then, the photoresist pattern is removed and pure water cleaning is performed (n). The second metal thin film used in this step has low electrical specific resistance, good contact characteristics with the ohmic contact film 8, and good contact with the semi-transmissive conductive film used for the pixel electrode 18. It is preferable to use Cr, Mo or the like having advantages such as characteristics (especially low electrical contact resistance).

  As a preferred embodiment, here, a Cr film having a thickness of 200 nm is formed as the second metal thin film by a sputtering method using a known Ar gas. A Cr target is used as the target. Further, sputtering is performed using a DC magnetron sputtering apparatus. Next, a photoresist pattern is formed in the third photolithography process. Then, the Cr film is wet etched using the photoresist pattern as a mask. Thereby, the source electrode 9, the drain electrode 10, the source wiring 12, and the source terminal 13 are formed. Next, the ohmic contact film 8 between the source electrode 9 and the drain electrode 10 is dry-etched using an etching gas containing a fluorine-based gas. Thereafter, the photoresist pattern is removed, and the channel region 11 of the TFT 108 is formed.

  Next, step D shown in FIG. 4 is performed. First, an interlayer insulating film 14 is formed as a passivation film so as to cover the source electrode 9, the drain electrode 10, the channel region 11, the source wiring 12, and the source terminal 13 (o). Then, a photoresist pattern is formed on the interlayer insulating film 14 by the fourth photolithography process (p). Using the photoresist pattern as a mask, the interlayer insulating film 14 is subjected to dry etching and patterned (q). Then, the photoresist pattern is removed and pure water cleaning is performed (r). Through the above steps, at least the pixel drain contact hole 15, the gate terminal part contact hole 16, and the source terminal part contact hole 17 are simultaneously formed.

  The pixel drain contact hole 15 penetrates to the surface of the drain electrode 10. That is, the interlayer insulating film 14 on the drain electrode 10 is removed, and the drain electrode 10 is exposed. The gate terminal contact hole 16 penetrates to the surface of the gate terminal 4. That is, the gate insulating film 6 and the interlayer insulating film 14 on the gate terminal 4 are removed, and the gate terminal 4 is exposed. The source terminal contact hole 17 penetrates to the surface of the source terminal 13. That is, the interlayer insulating film 14 on the source terminal 13 is removed, and the source terminal 13 is exposed.

  As a preferred embodiment, a chemical vapor deposition (CVD) method is used here, and film formation is performed under a substrate heating condition of about 300 ° C. Then, a silicon nitride (SiN) film having a thickness of 300 nm is formed as the interlayer insulating film 14. Next, a photoresist pattern is formed in the fourth photolithography process. Then, the SiN film is dry etched using a known fluorine-based gas. Thereafter, the photoresist pattern is removed, and a pixel drain contact hole 15, a gate terminal portion contact hole 16, and a source terminal portion contact hole 17 are formed.

  Finally, step E shown in FIG. 4 is performed. First, a semi-transmissive conductive film is formed on the interlayer insulating film 14 (s). The semi-transmissive conductive film is formed by a sputtering method using a mixed gas in which a gas containing at least nitrogen is added to an inert gas of Ar or Kr. Then, a photoresist pattern is formed on the semi-transmissive conductive film by the fifth photolithography process (t). Thereafter, using the photoresist pattern as a mask, the semi-transmissive conductive film is wet-etched and patterned (u). Thereafter, the photoresist pattern is removed (v). Through the above steps, the pixel electrode 18, the gate terminal pad 19, and the source terminal pad 20 are formed.

  The pixel electrode 18 is embedded in the pixel drain contact hole 15. Thereby, the pixel electrode 18 and the drain electrode 10 are electrically connected via the pixel drain contact hole 15. The gate terminal pad 19 is embedded in the gate terminal contact hole 16. As a result, the gate terminal pad 19 and the gate terminal 4 are electrically connected through the gate terminal contact hole 16. The source terminal pad 20 is embedded in the source terminal portion contact hole 17. Thereby, the source terminal pad 20 and the source terminal 13 are electrically connected via the source terminal portion contact hole 17.

  Through the above steps, the active matrix TFT array substrate 100 suitably used for the liquid crystal display device application according to the first embodiment is completed. The completed TFT array substrate 100 is preferably subjected to heat treatment at a temperature of about 200 to 300 ° C. As a result, static charges, stresses, etc. accumulated on the entire substrate can be removed or alleviated, and the electrical resistivity of the metal thin film can be lowered. Then, the TFT characteristics can be improved and stabilized.

As a preferred embodiment, here, an Al-45 mol% N alloy film having a thickness of 25 nm is formed as a semi-permeable conductive film by a reactive sputtering method using a known Ar gas mixed with N ₂ gas. Film. Further, sputtering is performed using a DC magnetron sputtering apparatus.

  Next, a photoresist pattern is formed in the fifth photolithography process. Then, the semi-transparent conductive film is wet-etched using a known chemical solution of phosphoric acid + nitric acid + acetic acid. Thereafter, the photoresist pattern is removed, and the pixel electrode 18, the gate terminal pad 19, and the source terminal pad 20 are formed. Thereafter, the substrate is held in the atmosphere at about 300 ° C. for 30 minutes, and heat treatment is performed to complete the desired TFT array substrate 100.

  As described above, in the TFT array substrate 100 according to the first exemplary embodiment, the pixel electrode 18 and the like are formed of the Al-45 mol% N alloy film. The Al-45 mol% N alloy film has characteristics as shown in FIG. FIG. 5 is a graph showing spectral characteristics of light transmittance and reflectance of an Al-45 mol% N alloy film. In FIG. 5, the vertical axis represents transmittance or reflectance (%), and the horizontal axis represents light wavelength (nm). The film thickness is 25 nm, which is the same as the film thickness described as the preferred embodiment.

  As shown in FIG. 5, the Al-45 mol% N alloy film has a transmittance of about 20 to 30% in the light wavelength range of 300 to 800 nm. The Al-45 mol% N alloy film has a reflectance of about 30 to 40% in the light wavelength range of 300 to 800 nm. For example, an Al-45 mol% N alloy film has a transmittance of 24.5% and a reflectance of 37.5% at a light wavelength of 550 nm. Thus, the Al-45 mol% N alloy film has semi-permeability. Further, the Al-45 mol% N alloy film has conductivity with an electrical specific resistance value of 2780 μΩcm.

  As described above, in the first embodiment, the pixel electrode 18 is formed of a single layer Al-45 mol% N alloy film having both the semi-transmission characteristic of light and electrical conductivity. Therefore, a transflective liquid crystal display panel can be realized without separately forming a reflective pixel electrode made of an Al alloy film and a transparent pixel electrode made of ITO or the like as in a conventionally known configuration. Therefore, it is not necessary to use a film formation chamber having ITO and Al material sources as in the prior art. Furthermore, it is not necessary to etch each film using separate chemicals and equipment in pattern processing. For this reason, it is possible to manufacture with high production capacity and high yield by reducing processes. In addition, the semi-transparent conductive film of the first embodiment is mainly composed of Al, and can be wet-etched with a conventionally known Al etching chemical solution, so that the manufacturing cost can be reduced.

  In the TFT array substrate 100 shown in FIG. 3, the gate insulating film 6 and the interlayer insulating film 14 are left in the lower layer of the pixel electrode 18, but may be removed as shown in FIG. FIG. 6 is a cross-sectional view showing another configuration of the TFT array substrate 100. As shown in FIG. 6, the gate insulating film 6 and the interlayer insulating film 14 are removed in most of the lower layer of the pixel electrode 18. The pixel electrode 18 is directly formed on the insulating substrate 1. An interlayer insulating film 14 is formed on the drain electrode 10. Therefore, like the TFT array substrate 100 shown in FIG. 3, the pixel electrode 18 and the drain electrode 10 are electrically connected via the pixel drain contact hole 15.

  A gate insulating film 6 and an interlayer insulating film 14 are formed on the auxiliary capacitance electrode 5. Therefore, like the TFT array substrate 100 shown in FIG. 3, the pixel electrode 18 and the auxiliary capacitance electrode 5 are disposed to face each other via the gate insulating film 6 and the interlayer insulating film 14. As described above, by removing the gate insulating film 6 and the interlayer insulating film 14 below the pixel electrode 18, it is possible to increase the amount of transmitted backlight light incident on the semi-transmissive conductive film of the pixel electrode 18 from the back surface of the substrate. And a bright transmissive display image can be obtained.

  The TFT array substrate 100 shown in FIG. 6 removes the gate insulating film 6 and the interlayer insulating film 14 in the formation region of the pixel electrode 18 simultaneously with the contact holes 15, 16, 17 in the fourth photolithography process. It is formed by.

Modification 1 of translucent conductive film
In the above embodiment, an Al-45 mol% N alloy film is used as the semi-permeable conductive film, but the present invention is not limited to this. Any Al—N alloy film can be used within a range satisfying optical characteristics (transmittance, reflectance) and electrical characteristics (specific resistance value). A modification will be described below.

  In general, it is known that in a metal film using a sputtering method, light transmittance appears by reducing the film thickness. However, in the case of an Al film, a transmittance of 1 to 5% appears at an extremely thin film thickness of about 5 to 10 nm. Therefore, in the case of an Al film, in order to obtain a transmittance of at least 5% that is practical as a semi-permeable film, the film thickness must be 10 nm or less.

  The light transmissivity of such an extremely thin metal thin film is derived from gaps between island-like metal grains existing in the process of film growth and hole defects in the film. For this reason, there is a drawback in that the transmittance characteristic depends on the material of the substrate substrate on which the film is formed, the cleanliness, etc., and it is difficult to control the transmittance without variation. Furthermore, when there is a level difference or unevenness due to a wiring pattern or the like on the substrate base, there is a drawback that the film is disconnected at these portions, so-called step disconnection occurs, and a conductive defect is likely to occur. In order to eliminate these problems, the film thickness needs to be at least 10 nm or more, more preferably 20 nm or more.

  FIG. 7 is a graph in which the light transmittance at a wavelength of 550 nm of the Al—N alloy film with the film thickness distributed between 10 and 100 nm is plotted against the N composition ratio of the film. In FIG. 7, the vertical axis represents the transmittance (%) of light at a wavelength of 550 nm, and the horizontal axis represents the N composition ratio (mol%) of the Al—N film. FIG. 7 shows the relationship between transmittance and N composition ratio when the film thickness is 10 nm, 25 nm, 50 nm, and 100 nm. As shown in FIG. 7, the transmittance increases as the N composition ratio increases. That is, the reflectance decreases as the N composition ratio increases. Further, the transmittance greatly depends on the film thickness, and the transmittance decreases as the film thickness increases. An N composition ratio of at least 40 mol% is preferable because a transmittance of 5% or more can be obtained even when the film thickness is 100 nm.

  FIG. 8 is a graph showing the N composition ratio dependency of the specific resistance value of the Al—N alloy film measured at a film thickness of 100 nm. In FIG. 8, the vertical axis represents specific resistance (Ωcm), and the horizontal axis represents the N composition ratio (mol%) of the Al—N alloy film. As shown in FIG. 8, the specific resistance value increases as the N composition ratio increases. For example, when the N composition ratio is 40 mol%, the specific resistance value is about 0.00025 Ω · cm (= 250 μΩ · cm). On the other hand, in the vicinity of 50 mol% at which the N composition ratio becomes the Al—N stoichiometric composition ratio, the specific resistance value exceeds 10 Ω · cm, which deviates from a practical conductive region. For this reason, it is preferable that the N composition ratio does not exceed 50 mol%. Further, by making the N composition ratio less than 50 mol%, wet etching can be performed without generating etching residue using a conventionally known Al etching chemical.

  From the above, in order to satisfy practical optical characteristics and electrical characteristics, the N composition ratio of the Al—N alloy film is preferably 40 mol% or more and less than 50%. In the above example, a film in which Al is contained in an amount of 40 mol% or more and less than 50 mol% is used as the semipermeable conductive film, but the present invention is not limited thereto. It is sufficient that at least 40 mol% or more and less than 50 mol% of nitrogen is included in either Al or an alloy containing Al as a main component.

  Further, within the above range, the specific resistance value of the semi-transmissive conductive film is 250 μΩ · cm or more and 10 Ω · cm or less, and can be practically used as the pixel electrode 18, for example. Further, in order to suppress defects such as step breakage in the semi-transmissive conductive film, the film thickness is set to at least 10 nm or more, more preferably 20 nm or more.

  FIG. 9 is a graph showing the N composition ratio dependence of the transmittance and reflectance of light of the Al—N alloy film at a wavelength of 550 nm. In FIG. 9A, the film thickness of the Al—N alloy film is 25 nm, in FIG. 9B, the film thickness of the Al—N alloy film is 50 nm, and in FIG. 9C, the film thickness of the Al—N alloy film is 100 nm. It is a graph when fixed to. In FIG. 9, the vertical axis represents the reflectance or transmittance (%) at a light wavelength of 550 nm, and the horizontal axis represents the N composition ratio (mol%) of the Al—N alloy film.

  By distributing the N composition ratio within the range of 40 mol% or more and less than 50 mol%, it is possible to distribute the transmittance and reflectance of the film. And what is necessary is just to set a film thickness and a composition ratio arbitrarily according to the characteristic requested | required. That is, by adding Al as a main component and adding N thereto, the Al film is provided with light transmittance, and by controlling its composition ratio and process parameters, light transmittance, light reflectivity, and A translucent conductive film having electrical conductivity at the same time is obtained. Based on the knowledge obtained above, an example of a semi-transparent conductive film (single layer film) that can be suitably used in the first embodiment and examples of its optical characteristics and electrical characteristics shown in Table 1 will be described later. It is shown in 1.

Embodiment 2
In Embodiment 1 described above, an example in which a single-layer film of an Al—N alloy film is used as the semi-transmissive conductive film and the semi-transmissive pixel electrode using the conductive film is shown. Indium oxide (In ₂ O ₃ ) -based, tin oxide (SnO ₂ ) -based and zinc oxide (ZnO) -based oxide transparency used as transparent pixel electrodes in conventional transmissive or transflective liquid crystal display devices The specific resistance value of the conductive film is at most 1000 μΩcm.

  When used as a pixel electrode of a relatively small size liquid crystal display device, it is possible to use the single layer film of the Al—N alloy film having a specific resistance value of several Ωcm or less as shown in the first embodiment. However, when it is used as a pixel electrode of a relatively large size display (which is related to the pixel area depending on the number of pixels but is approximately 20 inches or more), the specific resistance value is 1000 μΩcm, which is equivalent to that of the conventional oxide transparent conductive film. The following is more preferable. When a single layer film of an Al—N alloy film corresponds to such a large size, as can be seen from Example 1 of Table 1 described later, the N composition ratio is limited to around 40 mol%. Become. The second embodiment shows a configuration example for making the specific resistance value of the Al—N semitransparent conductive film equal to or less than that of a conventional oxide transparent conductive film.

  The second embodiment is different from the first embodiment in that the translucent conductive film of the pixel electrode 18 is formed of a laminated film, and the other configuration is the same as that of the first embodiment. Therefore, the overlapping description is omitted or simplified as appropriate. First, the TFT array substrate 100 according to the second exemplary embodiment will be described with reference to FIGS. FIG. 10 is a cross-sectional view of the TFT array substrate 100 according to the second exemplary embodiment. The plan view of the TFT array substrate 100 is the same as FIG. FIG. 10 is a cross-sectional view illustrating a configuration taken along line AA ′, line BB ′, and line CC ′ of FIG. Note that FIG. 10 illustrates the configuration of the gate terminal portion, the source terminal portion, and the pixel 105 in order from the left. FIG. 11 is a cross-sectional view showing the configuration of the semi-transmissive conductive film of the pixel electrode 18.

  As shown in FIGS. 10 and 11, the pixel electrode 18 is formed of a semi-permeable film that is a laminated film in which nitrogen-containing films and metal films are alternately laminated. Specifically, the pixel electrode 18 has a three-layer structure in which a nitrogen-containing film 18a, a metal thin film 18b, and a nitrogen-containing film 18c are sequentially stacked. That is, the pixel electrode 18 is formed by a semi-transparent conductive film having a three-layer structure.

  The lower and upper nitrogen-containing films 18a and 18c have substantially the same composition and thickness. Of course, not limited to this, the nitrogen-containing films 18a and 18c may have different compositions and film thicknesses. As the nitrogen-containing films 18a and 18c, those shown in Embodiment 1 can be used as appropriate. That is, a semi-transmissive conductive film within the range shown in the first modification of the semi-transmissive conductive film in Embodiment 1 can be used.

  The intermediate metal thin film 18b is thinner than the nitrogen-containing films 18a and 18c. The metal thin film 18b is a metal film of either Al or an alloy containing Al as a main component. Moreover, the metal thin film 18b contributes to the reduction of the specific resistance value, and may or may not contain N. However, a film having a specific resistance at least smaller than that of the nitrogen-containing films 18a and 18c is used.

  According to the second embodiment, the same effects as those of the first embodiment can be obtained. In addition, in the semi-transmissive conductive film according to the second embodiment, the metal thin film 18b is formed as an intermediate layer. For this reason, the specific resistance value can be reduced as compared with the semi-transmissive conductive film of the first embodiment.

  Next, a method for manufacturing the TFT array substrate 100 will be described. First, as in the first embodiment, the process up to step D in FIG. 4 is performed. In other words, the process is performed in the same manner as in the first embodiment until the semi-transmissive conductive film to be the pixel electrode 18 is formed.

  Then, nitrogen-containing films and metal films are alternately stacked on the interlayer insulating film 14. Specifically, a nitrogen-containing film 18a, a metal thin film 18b, and a nitrogen-containing film 18c are sequentially formed on the interlayer insulating film 14 to form a three-layered film. As the nitrogen-containing films 18a and 18c, an Al—N alloy film in which N is added to Al is formed. Similarly to the semipermeable conductive film of the first embodiment, the nitrogen-containing films 18a and 18c are formed by a sputtering method using a mixed gas obtained by adding a gas containing at least nitrogen to an inert gas of Ar or Kr. The An Al metal thin film is formed as the metal thin film 18b.

  Thereafter, the nitrogen-containing film 18a, the metal thin film 18b, and the nitrogen-containing film 18c are patterned by the fifth photolithography process and etching. Thereby, the pixel electrode 18, the gate terminal pad 19, and the source terminal pad 20 are formed. Note that the second embodiment may have a structure in which the gate insulating film 6 and the interlayer insulating film 14 under the pixel electrode 18 are removed as in the first embodiment.

As a preferable embodiment, the formation of the Al-45 mol% N alloy film as the nitrogen-containing layer 18a by reactive sputtering using a mixed gas of _{N 2} gas to the known Ar gas to a thickness of 10 nm. An Al target is used as the target. Further, sputtering is performed using a DC magnetron sputtering apparatus.

Next, an Al metal thin film having a thickness of 5 nm is formed as the metal thin film 18b by sputtering using only Ar gas. Further successively, the formation of the Al-45 mol% N alloy film to a thickness of 10nm as a nitrogen-containing layer 18c by a reactive sputtering method using a gas obtained by mixing _{N 2} gas into the Ar gas again.

  Thereby, a three-layer laminated film having a total film thickness of 25 nm is formed as a semi-transmissive conductive film. Next, a photoresist pattern is formed on the semi-transmissive conductive film in the fifth photolithography process. Then, the semi-transparent conductive film is wet-etched using a known chemical solution of phosphoric acid + nitric acid + acetic acid to remove the photoresist pattern. Thereby, the pixel electrode 18, the gate terminal pad 19, and the source terminal pad 20 are formed. Thereafter, the substrate is held in the atmosphere at about 300 ° C. for about 30 minutes to perform heat treatment, and the TFT array substrate 100 according to the second embodiment is completed.

  The three-layer laminated semi-transparent conductive film applied in the second embodiment has characteristics as shown in FIG. FIG. 12 is a graph showing spectral characteristics of light transmittance and reflectance of the semi-transmissive conductive film according to the second embodiment. In FIG. 12, the vertical axis represents transmittance or reflectance (%), and the horizontal axis represents light wavelength (nm). The film thickness is 10 nm for the upper and lower Al-45 mol% N alloy films, and 5 nm for the Al metal thin film in the intermediate layer, similar to the film thickness described as the preferred embodiment.

  As shown in FIG. 12, the Al-45 mol% N / Al / Al-45 mol% N film as the semi-transmissive conductive film has a transmittance of about 10 to 20% in the light wavelength range of 300 to 800 nm. Have. The Al-45 mol% N / Al / Al-45 mol% N film has a reflectance of about 30 to 50% in the light wavelength range of 300 to 800 nm. For example, an Al-45 mol% N / Al / Al-45 mol% N film has a transmittance of 14.8% and a reflectance of 46.3% at a light wavelength of 550 nm. Thus, the Al-45 mol% N / Al / Al-45 mol% N film has semi-transparency. Furthermore, the Al-45 mol% N / Al / Al-45 mol% N film has a conductivity with an electrical specific resistance value of 101 μΩcm.

  As described above, according to the translucent conductive film according to the second embodiment, the specific resistance value can be lowered by forming the metal thin film 18b as the intermediate layer as compared with the first embodiment.

  In addition, a laminated structure in which an Al-based metal thin film is sandwiched as an intermediate layer can be formed by switching the film forming gas without changing the target. For this reason, a semipermeable conductive film can be easily formed. Furthermore, since the semi-permeable conductive film can be etched in a batch using a known chemical solution of phosphoric acid + nitric acid + acetic acid, it can be produced without increasing the number of processes compared to a single layer film.

Modification 2 of semi-permeable conductive film
In the above embodiment, an Al-45 mol% N / Al / Al-45 mol% N film is used as the semi-transmissive conductive film, but the present invention is not limited to this. Any film can be used as long as it satisfies the optical characteristics (transmittance, reflectance) and electrical characteristics (specific resistance value).

  Table 1 is a table showing optical characteristics (transmittance and reflectance) and electrical characteristics (specific resistance values) at the N composition ratio and film thickness of each Al—N alloy film. Example 1 in Table 1 shows an example of a semi-transparent conductive film (single layer film) that can be suitably used in Embodiment 1. Example 2 in Table 1 shows an example of a semi-transmissive conductive film (three-layer laminated film) that can be suitably used in the second embodiment. As a comparative example, an Al-50 mol% N alloy film (single layer film) is shown.

  Here, the semi-transmissive conductive films of Examples 1 and 2 will be compared. As Example 1, a single-layer Al-45 mol% N alloy film having a film thickness of 25 nm is used. In the second embodiment, a laminated film in which an Al-45 mol% N alloy film having a thickness of 10 nm, an Al metal thin film having a thickness of 5 nm, and an Al-45 mol% N alloy film having a thickness of 10 nm are sequentially laminated is used. . That is, the total film thickness is 25 nm in any semi-transmissive conductive film. The N composition ratio is 45 mol% in any Al—N alloy film.

  First, the transmittance and reflectance at a wavelength of 550 nm will be compared. The transmittance is 24.5% in Example 1, and 14.8% in Example 2. The reflectance is 37.4% in the first embodiment and 46.3% in the second embodiment. Thus, even if the total film thickness is the same as 25 nm, in Example 2, since the Al metal thin film having a thickness of 5 nm is sandwiched as the intermediate layer, the reflectance increases, and the transmittance decreases accordingly.

  Next, the conductivity will be compared. The electrical specific resistance value is 2780 μΩcm in Example 1 and 101 μΩcm in Example 2. That is, compared with Example 1, in Example 2, an electrical specific resistance value can be reduced significantly. In other words, the specific resistance value is greatly reduced by using a laminated structure of an Al—N alloy film and a low resistance Al alloy film as compared with a single layer Al—N alloy film. In other words, the conductivity can be significantly improved in the second embodiment compared to the first embodiment. Note that the Al-50% N alloy film shown in the comparative example has poor conductivity for any film thickness.

  Thus, if the semi-transmissive conductive film has a laminated structure in which the Al metal thin film is sandwiched between the Al—N alloy films as in Example 2, the film thickness of each layer, particularly the Al layer as the intermediate layer. By adjusting the thickness of the metal thin film, there is an advantage that the light transmission characteristic and the reflection characteristic can be arbitrarily changed and the specific resistance value can be greatly reduced.

  In addition, since the transmittance | permeability will fall when the Al metal thin film as an intermediate | middle layer becomes thick, it is preferable that the thickness of an Al metal thin film is less than 10 nm. Further, as shown in Table 1, when the N composition ratio of the Al—N alloy film is increased, the Al metal thin film has a transmittance of 5% or more even when the thickness of the Al metal thin film is 10 nm. For example, when the N composition ratio is 45 mol%, the transmittance is 6.5% even when the thickness of the Al metal thin film is 10 nm. For this reason, if the N composition ratio is increased, the pixel electrode 18 can be used even if the thickness of the Al metal thin film is 10 nm. Further, as described in Embodiment 1, the total film thickness is at least 10 nm or more, more preferably 20 nm or more.

  In the second embodiment, as a preferred example, a semi-transmissive conductive film to be the pixel electrode 18 is formed of a three-layer laminated film of Al-45 mol% N alloy film / Al metal thin film / Al-45 mol% N alloy film. did. The thickness of each layer was 10 nm / 5 nm / 10 nm, with a total thickness of 25 nm. Not limited to this, other semi-transparent conductive films shown in Example 2 of Table 1 may be used.

  Of course, it is not limited to the case shown in Table 1, and based on an arbitrary Al-based alloy film and an Al-N-based alloy film in which N is contained in these Al-based alloy films, desired optical characteristics are obtained. The present invention can be applied in any combination as long as electrical characteristics can be obtained. That is, an alloy film containing Al as a main component may be used as the metal thin film 18b, and an alloy film containing N in an alloy film containing Al as a main component may be used as the nitrogen-containing films 18a and 18c. Even in this case, the thickness of the Al-based alloy film (Al-based metal thin film) is preferably less than 10 nm. The total film thickness is at least 10 nm or more, more preferably 20 nm or more.

  Further, the present invention is not limited to the three-layer laminated film, and for example, a five-layer laminated film as shown in FIG. 13 may be used. FIG. 13 is a cross-sectional view showing another configuration of the semi-transmissive conductive film of the pixel electrode 18.

  In FIG. 13, the pixel electrode 18 is formed of a five-layer laminated film in which a nitrogen-containing film 18a, a metal thin film 18b, a nitrogen-containing film 18c, a metal thin film 18d, and a nitrogen-containing film 18e are sequentially laminated. That is, the pixel electrode 18 is formed by five layers of semi-transmissive conductive film. Note that the compositions and film thicknesses of the nitrogen-containing films 18a, 18c, and 18e are substantially the same. The metal thin films 18b and 18d have substantially the same composition and film thickness. Of course, the nitrogen-containing films 18a, 18c, and 18e may have different compositions and film thicknesses. Similarly, the metal thin films 18b and 18d may have different compositions and film thicknesses. At this time, the total thickness of the metal thin films 18b and 18d is preferably less than 10 nm. The total film thickness of the five layers constituting the semi-transmissive conductive film is at least 10 nm, more preferably 20 nm.

  In FIGS. 11 and 13, the lowermost layer and the uppermost layer are both nitrogen-containing films such as an Al—N alloy film in the laminated film structure of the semi-permeable conductive film, but the present invention is not limited to this. For example, a laminated film structure in which one or both of the lowermost layer and the uppermost layer are made of a metal thin film such as an Al-based metal thin film may be used. However, in this case, depending on the film thickness of the Al-based metal thin film, the reflection characteristics of light from the lowermost layer or the uppermost layer may be superior, and the transmittance may be significantly reduced. When obtaining a translucent conductive film having a good balance between light transmission characteristics and reflection characteristics, as shown in FIGS. 11 and 13, a metal thin film is sandwiched between upper and lower layers by a nitrogen-containing film as a semi-permeable film. Such a laminated structure is more preferable.

Embodiment 3
In the third embodiment, an organic resin film is provided as a new interlayer insulating film. Other configurations and the like are the same as those in the first embodiment. Therefore, the overlapping description is omitted or simplified as appropriate. FIG. 14 is a plan view showing the configuration of the TFT array substrate 100 according to the third embodiment. FIG. 15 is a cross-sectional view illustrating a configuration taken along line AA ′, line BB ′, and line CC ′ of FIG. Here, the AA ′ line indicates the configuration of the pixel 105, the BB ′ line indicates the configuration of the source terminal portion, and the CC ′ line indicates the configuration of the gate terminal portion. Note that FIG. 15 illustrates the structure of the gate terminal portion, the source terminal portion, and the pixel 105 in order from the left.

  As shown in FIG. 15, an organic resin film 21 is formed on the interlayer insulating film 14. Further, the organic resin film 21 is also removed in the contact holes 15, 16, and 17. The organic resin film 21 has an uneven shape 22. A plurality of uneven shapes 22 are formed on substantially the entire pixel 105 except for the portion of the TFT 108. The pixel electrode 18 is formed on the concavo-convex shape 22 of the organic resin film 21. As described above, by forming the uneven shape 22 in the pixel region, the reflected light can be scattered.

  According to the third embodiment, the same effect as in the first embodiment can be obtained. Further, in the third embodiment, irregularities are formed in the organic resin film 21 provided in the lower layer of the pixel electrode 18. By making the surface of the pixel electrode 18 a light scattering surface, it becomes difficult for an observer who displays an image by reflected light to see the observer's own face or an external image of the background due to specular reflection. Thereby, there is an advantage that a high-quality reflected image can be displayed.

  Next, a manufacturing method of the TFT array substrate 100 according to the third embodiment will be described. First, similarly to the first embodiment, the processes up to step C in FIG. 4 are performed. Then, an interlayer insulating film 14 and an organic resin film 21 are sequentially formed so as to cover the source electrode 9, the drain electrode 10, the channel region 11, the source wiring 12, and the source terminal 13. Then, the organic resin film 21 is patterned by the fourth photolithography process. Thereby, the organic resin film 21 in the portion where the pixel drain contact hole 15, the gate terminal contact hole 16, and the source terminal contact hole 17 are formed is removed. At the same time, an uneven shape 22 is formed on the surface of the organic resin film 21.

  Then, using the organic resin film 21 as a mask, the interlayer insulating film 14 and the gate insulating film 6 are etched. Thereby, the pixel drain contact hole 15, the gate terminal part contact hole 16, and the source terminal part contact hole 17 are formed.

  As a preferred embodiment, a chemical vapor deposition (CVD) method is used here, and film formation is performed under a substrate heating condition of about 300 ° C. Then, a silicon nitride (SiN) film is formed as the interlayer insulating film 14 to a thickness of 100 nm. Thereafter, a photosensitive organic resin film is formed as the organic resin film 21 to an average thickness of about 3.5 μm using a spin coating method. Note that the surface of the organic resin film 21 is substantially flat. That is, if there are irregularities or steps in the lower layer, the film thickness is partially different strictly. As the photosensitive organic resin film, an acrylic resin having high light transmittance, such as PC335 manufactured by JSR Corporation, can be suitably used.

  Thereafter, a first exposure is performed using a photomask pattern for forming the pixel drain contact hole 15, the gate terminal portion contact hole 16, and the source terminal portion contact hole 17 by a photolithography process. Next, second exposure is performed using a photomask for forming the light scattering irregularities 22 on the surface of the pixel region of the photosensitive organic resin film. Here, the second exposure is an exposure amount of about 20% to 40% of the first exposure. Thereafter, the photosensitive organic resin film is developed using an organic alkali developer. As a result, the pixel drain contact hole pattern, the gate terminal portion contact hole pattern, the source terminal portion contact hole pattern, and the light scattering uneven shape 22 are simultaneously formed in the photosensitive organic resin film.

  The reflection / scattering characteristics of light can be changed by changing the depth or the planar shape of the uneven shape 22. Therefore, the irregular shape 22 may be arbitrarily designed so as to obtain a desired scattering characteristic. In order to obtain practical scattering characteristics, the uneven height of the uneven shape 22 is preferably set in a range of approximately 0.05 μm to 1 μm. The height of the concavo-convex shape 22 can be adjusted by adjusting the exposure amount of the second exposure. Next, the gate insulating film 6 and the interlayer insulating film 14 under the contact hole pattern are removed by dry etching using a known fluorine-based gas. Thus, the pixel drain contact hole 15, the gate terminal portion contact hole 16, and the source terminal portion contact hole 17 are formed.

  Then, the pixel electrode 18, the gate terminal pad 19, and the source terminal pad 20 are formed by the same process as the process E of FIG. 3 described in the first embodiment. Thereafter, heat treatment is performed by holding the substrate in the atmosphere at about 200 ° C. for 30 minutes. Thereby, the TFT array substrate 100 according to the third exemplary embodiment is completed.

  In the third embodiment, irregularities are formed in the organic resin film 21 provided in the lower layer of the pixel electrode 18. Thereby, there is an advantage that a high-quality reflected image can be displayed. In the third embodiment, the heat treatment is performed at about 200 ° C., but this may be changed according to the heat resistance of the organic resin film 21 to be used. When the heat treatment is performed at a temperature higher than the heat resistance of the organic resin film 21, the organic resin film 21 is discolored and causes a decrease in transmittance.

  15 illustrates the pixel electrode 18 formed of a single-layer semi-transparent conductive film as in the first embodiment, the present invention is not limited to this. As in the second embodiment, the pixel electrode 18 may be formed using a semi-transmissive conductive film in which a plurality of films are stacked. Moreover, the semipermeable conductive film can be used as the composition and film thickness of the semipermeable conductive film within the ranges shown in the modified examples of these embodiments.

In the above first to third embodiments, the Al—N alloy film in which N element is added to Al is described as the semi-permeable conductive film, but the present invention is not limited to this. In addition to the N element, an Al-MN-based alloy to which another element M is added in order to improve heat resistance such as hillocks and corrosion resistance against chemicals may be used. Even in this case, it is possible to easily form an Al—M—N alloy film having optical transparency by a reactive sputtering method in an Ar + N ₂ mixed gas using an Al—M alloy target.

  Further, in the first to third embodiments, an active matrix TFT array substrate for a liquid crystal display device using a liquid crystal has been described. However, the translucent conductive film of the present invention used as a pixel electrode is suitable for this device application. There is no limit. For example, it can be suitably used for other devices as a general semipermeable membrane, a semitransmissive plate, and a half mirror. In particular, it can be more suitably used for applications requiring electrical conductivity.

1 Insulating substrate, 2 Gate electrode, 3 Gate wiring, 4 Gate terminal,
5 Auxiliary capacitance electrode, 6 Gate insulating film, 7 Semiconductor film, 8 Ohmic contact film,
9 source electrode, 10 drain electrode, 11 channel region, 12 source wiring,
13 source terminal, 14 interlayer insulating film, 15 pixel drain contact hole,
16 Gate terminal contact hole, 17 Source terminal contact hole,
18 pixel electrode, 18a nitrogen-containing film, 18b metal thin film, 18c nitrogen-containing film,
18d metal thin film, 18e nitrogen-containing film, 19 gate terminal pad,
20 source terminal pad, 21 organic resin film, 22 uneven shape,
100 TFT array substrate, 101 display area, 102 frame area,
103 scanning signal driving circuit, 104 display signal driving circuit, 105 pixels,
106 External wiring, 107 External wiring, 108 TFT, 109 Auxiliary capacitance

Claims (5)

A semi-transmissive film having optical transmission characteristics and reflection characteristics as optical characteristics,
A nitrogen-containing film containing at least 40 mol% or more and less than 50 mol% nitrogen in either aluminum or an alloy containing aluminum as a main component ;
It is a laminated film in which aluminum or an aluminum-based alloy metal film is alternately laminated,
The nitrogen-containing film is a semi-transmissive film having a transmittance of 20 to 30% at a film thickness of 25 nm in the range of 300 to 800 nm and a reflectance of about 30 to 40% . The semipermeable membrane according to claim 1, wherein the nitrogen-containing membrane has a specific resistance value of 250 μΩcm or more. The semipermeable membrane according to claim 1 or 2 , wherein a specific resistance value of the nitrogen-containing membrane is 10 Ωcm or less. The semipermeable membrane according to any one of claims 1 to 3, wherein the thickness of the metal film is less than 10 nm. The semipermeable membrane according to any one of claims 1 to 4 , wherein the total film thickness is 10 nm or more.

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