JP2008164668A - Liquid crystal display element and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that a short circuit is highly likely to occur between two metal light shielding films, and lower the yield, in a conventional liquid crystal display element wherein two metal light shielding films aligned in a vertical direction have a large overlapping area and film thickness of a light shielding insulating film disposed between the two metal light shielding films is small. <P>SOLUTION: A metal wire 40 is formed on a second interlayer film 27 with a predetermined gap to a first metal light shielding film 28 so as to electrically connect a reflection electrode 13 and the source 10c of a pixel transistor 10. Furthermore, by forming a second metal light shielding film 41 in a gap between the first metal light shielding film 28 and the metal wire 40, the first metal light shielding film 28 and the second metal light shielding film 41 are arraged adjacent to each other in the horizontal direction, while retaining a function to prevent leakage of light passing through the gap of the reflection electrode 13 into a direction toward the pixel transistor, the overlapping area between the first metal light shielding film 28 and the second metal light shielding film 41 is reduced as compared with the conventional liquid crystal display element in which two metal light shielding films are overlapped with each other in the vertical direction. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a liquid crystal display element and a method for manufacturing the same, and in particular, a liquid crystal is sealed between a reflective electrode constituting a pixel on a first substrate and a counter electrode common to all pixels on a second substrate. The present invention relates to a reflection-type liquid crystal display element in which incident light is incident on and reflected from a reflection electrode through a counter electrode and a liquid crystal, and the reflection light is modulated for each reflection electrode corresponding to a video signal, and a method for manufacturing the same.

  Recently, there is an increasing demand for a projection display device for displaying a video on a large screen, such as a display for displaying a high-definition video such as a high-definition video. The projection type display device is roughly classified into a transmission type and a reflection type, and both types use a spatial light modulation unit using an LCD (Liquid Crystal Display) panel, and the LCD panel. The projection light is obtained by causing the readout light to enter the light source and modulating the incident light in correspondence with the video signal in units of pixels.

  Here, the LCD panel is an active matrix formed on an active matrix substrate in which a plurality of pixel transistors such as thin film transistors formed on a semiconductor substrate and a plurality of pixel electrodes whose potentials are controlled by the pixel transistors are arranged. The circuit includes a common electrode formed on a transparent substrate (such as a glass substrate) and a liquid crystal layer sealed between the active matrix substrate and the common electrode, and a potential difference between the common electrode and each pixel electrode Is a liquid crystal display element that modulates readout light by changing the pixel image for each pixel electrode corresponding to the video signal and controlling the orientation of the liquid crystal.

  Next, the configuration of the projection display device will be described by taking a reflective liquid crystal display element (LCD panel) as an example. FIG. 5 is a block diagram showing an example of an active matrix circuit of a reflective LCD panel. The active matrix circuit shown in FIG. 5 includes a pixel portion 1 in which nine pixels are arranged in a matrix of 3 rows and 3 columns, a horizontal shift register circuit 2, and a vertical shift register circuit 3, and further includes a pixel portion. Each pixel group in one column is connected to the horizontal shift register circuit 2 via a vertical signal wiring 4 and a video switch, and a horizontal gate wiring 8 for each pixel group in each row of the pixel unit 1. Is connected to the vertical shift register circuit 3 via

  Each pixel in the pixel unit 1 includes at least a pixel transistor 10, a storage capacitor 11, a counter electrode 12, and a reflective electrode 13, as will be described later. The counter electrode 12 is a common electrode common to all pixels, and the reflective electrode 13 is a pixel electrode provided for each pixel. The pixel transistor 10 includes a gate electrode 10a, a drain 10b, and a source 10c, and is an FET represented by an equivalent circuit symbol 14 shown in FIG. The holding capacitor 11 can be represented as a capacitor 15 in the equivalent circuit.

  The video switch includes a P-channel field effect transistor (FET) 5 and an N-channel FET 6 whose drains and sources are connected to each other, and an inverter 7 for inputting signals of different logic values to the gates of the FETs 5 and 6. It consists of. The drains of the FETs 5 and 6 are connected to the video line 9. The three video switches are sequentially turned on in a predetermined cycle by a signal from the horizontal shift register circuit 2. Further, the vertical shift register 3 outputs a signal for sequentially turning on the pixel transistors in the pixels of each row from the top to the bottom, for example, in a predetermined horizontal scanning cycle.

  Accordingly, each pixel in the pixel unit 1 is sequentially selected in units of pixels by each signal from the horizontal shift register circuit 2 and the vertical shift register circuit 3, and the video line 9 and the video signal are stored in the storage capacitor of the selected pixel. The video signal input through the switch is supplied and written in the form of electric charges.

  FIG. 6 is a schematic cross-sectional view of an example of one pixel of the pixel unit 1. In the figure, the same components as those in FIG. In FIG. 6, a drain 10 b and a source 10 c, which are diffusion layers having a conductivity type opposite to that of the well 22, are formed in the well 22 formed in the silicon substrate 21, and the gate electrode 10 a is formed on the silicon substrate 21 via an oxide film. Are formed to constitute the pixel transistor 10 described above using a MOS FET. In addition, a diffusion layer 23 is formed in a region different from the well 22 of the silicon substrate 21, and a polysilicon layer 24 is formed on the diffusion layer 23 via an oxide film. It is configured.

  On the gate electrode 10a and the polysilicon layer 24, a first interlayer film 25, a first metal 26, a second interlayer film 27, a first metal light shielding film (second metal) 28, a light shielding insulating film (third interlayer) Film) 29 and reflective electrode (third metal) 13 are laminated, and liquid crystal 30 is sealed between reflective electrode 13 and counter electrode 12. The pixel transistors 10 made of MOS type FETs formed on the surface of the silicon substrate 21 are arranged in a matrix corresponding to the pixel arrangement, and the first transistors are arranged through the openings of the first interlayer film 25 covering the upper surface. A source 10 c is connected to a first metal 26 made of aluminum and arranged in a matrix on the interlayer film 25.

  Here, as shown in FIG. 5, the plurality of pixel transistors 10 arranged in a matrix are sequentially driven, and the video signal to be displayed is held as a charge in the holding capacitor 11 connected to the pixel transistor 10. 6, the potential difference between the counter electrode 12 and the reflection electrode 13 shown in FIG. 6 is changed for each reflection electrode 13 in correspondence with the video signal, and between the reflection electrode 13 and the counter electrode 12 connected to the pixel transistor 10. The optical characteristics (orientation) of the liquid crystal 30 are controlled for each reflective electrode 13, transmitted through the counter electrode 12 and the liquid crystal 30, reflected by entering the reflective electrode 13, and transmitted through the liquid crystal 30 and the counter electrode 12 to the outside. The emitted readout light is modulated in units of reflective electrodes. For this reason, the reflection type liquid crystal display element has a structure in which light can be used nearly 100% unlike the conventional transmission type projector element, and both high definition and high luminance can be achieved.

  However, in the case of a reflective liquid crystal display element using the silicon substrate 21, when light is mixed into the diffusion electrode (source 10c) of the pixel transistor 10, photocarriers are generated, a leak current is generated, and fluctuations in the pixel electrode potential are caused. May cause. This fluctuation of the pixel electrode potential causes flicker and burn-in, so that it is necessary to minimize light leakage.

  Therefore, conventionally, a first metal light-shielding film 28 made of aluminum wiring is disposed below the gap of the reflective electrode 13 as shown in FIG. By taking a long length (optical path length) and absorbing light, the pixel transistor 10 is structured so as not to mix light.

  FIG. 7 is a schematic cross-sectional view showing an incident path of light in one pixel of the pixel unit 1 shown in FIG. In the figure, the same components as those in FIG. 6 are denoted by the same reference numerals, and the description thereof is omitted. As shown in FIG. 7, incident light transmitted through the counter electrode 12 and the liquid crystal 30 is reflected by the reflective electrode 13, but a part of the incident light is adjacent to the two reflective electrodes 13 as indicated by dotted arrows. Part of the light that passes through the gap and enters the light shielding film 28 and is reflected and reflected from the metal light shielding film 28 is repeatedly reflected by the lower surface of the reflective electrode 13 and the metal light shielding film 28, and the light gradually attenuates. However, a part of the reflected light passes through the gap between the metal light shielding films 28 and passes through the second interlayer film 27 and the first interlayer film 25, and the gate 10a, drain 10b, and source of the pixel transistor 10 are transmitted. 10c.

  The drain 10b and the source 10c, which are diffusion electrodes, form a PN junction with the well 22, in other words, it can be said that a photodiode is formed. For this reason, it is necessary to reduce the light reaching the drain 10b and the source 10c constituting the photodiode.

  Further, in order to reduce fluctuations in the pixel electrode potential due to light leakage, the storage capacitor 11 is necessary. If the light leakage is large, the storage capacitor 11 must be increased accordingly, which hinders pixel miniaturization. It has become. In view of this, a liquid crystal display element that uses two metal light shielding films to prevent light leakage current has been conventionally proposed (see, for example, Patent Documents 1 and 2).

  FIG. 8 is a schematic cross-sectional view of one pixel of the conventional liquid crystal display element described in Patent Document 2. In the figure, the same components as those in FIG. In FIG. 8, the source 10c of the pixel transistor 10 that is a MOSFET is connected to the polysilicon layer 24 of the storage capacitor 11 that holds the voltage, and the first metal is formed on the second interlayer insulating film 27 that covers them. The light shielding film 28 is provided so that light does not enter from the gap between two adjacent reflective electrodes 13.

  A light shielding insulating film 32 is formed on the first metal light shielding film 28. The light-shielding insulating film 32 usually uses an oxide film, and the film thickness is set to be less than 400 nm (for example, 200 nm) which is a thickness less than the wavelength of the color light incident on the substrate. Further, a second metal light-shielding film 33, a light-shielding insulating film (third interlayer film) 29, and the reflective electrode 13 are sequentially stacked on the light-shielding insulating film 32. The second metal light-shielding film (2.5 metal) 33 is made of, for example, titanium nitride (TiN). The element (the pixel transistor 10 and the storage capacitor 11) and the first metal light-shielding film 28 are electrically connected via a via hole 34, and the first metal light-shielding film 28 and the reflective electrode 13 are electrically connected via a via hole 35. Connected. These wirings for connecting the element and the reflective electrode and the reflective electrode 13 are formed of aluminum (Al), and an antireflection film is formed of titanium nitride on the metal light shielding films 28 and 33.

  The reflective liquid crystal display element reflects light having a wavelength of 400 nm to 700 nm in the visible light region to perform color display. Therefore, since it is not necessary to use light having a wavelength of less than 400 nm, it is not necessary to make light incident on the liquid crystal panel.

  Here, if the film thickness of the light shielding insulating film 32 is set to less than 400 nm, the light wave incident on the light shielding insulating film 32 is absorbed or reflected by the metal in the vertical direction. In addition, the light shielding effect can be maximized. Naturally, the first metal light-shielding film (second metal) 28 and the second metal light-shielding film (2.5 metal) 33 need to be insulated, so that the film thickness is less than 400 nm in consideration of the yield. The film thickness of the light shielding insulating film 32 is set.

  Further, since the light shielding insulating film 32 is formed by a CVD (chemical vapor deposition) method, as is well known, the in-plane variation of the wafer is suppressed. Therefore, the thickness of the light shielding insulating film 32 between the first metal light shielding film 28 and the second metal light shielding film 33 can be set relatively uniformly. Therefore, it can be created with less variation in the light shielding effect. For this reason, most of the light incident on the pixel transistor 10 from the reflective electrode 13 can be cut, and leakage current due to the light can be prevented.

JP 2002-040482 A JP 2004-206108 A

  However, in the conventional liquid crystal display element having the structure shown in FIG. 8, the vertical overlap area between the first metal light shielding film 28 and the second metal light shielding film 33 is large, and the first metal light shielding film 28 and the first metal light shielding film 28 Since the thickness of the light-shielding insulating film 32 between the two metal light-shielding films 33 is thin, if this overlap area is large, 36 in FIG. 8 between the first metal light-shielding film 28 and the second metal light-shielding film 33. There is a problem that the probability of short-circuiting increases at the position indicated by and the yield tends to decrease.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a liquid crystal display element capable of suppressing a decrease in yield due to a short between two metal light-shielding films and a method for manufacturing the same.

  Another object of the present invention is to reduce light leakage, thereby reducing flicker and burn-in, and having a small storage capacity for supporting the leakage current, and capable of miniaturizing a pixel, and a liquid crystal display element thereof An object is to provide a manufacturing method.

  In order to achieve the above object, a liquid crystal display element according to a first aspect of the present invention is a pixel including a reflective electrode that reflects incident light, a switching element connected to the reflective electrode, and a storage capacitor connected to the switching element. Are regularly arranged on the first substrate, a first light-shielding film is formed between the reflective electrode and the switching element via an insulating film, and a plurality of elements on the first substrate are arranged. The counter electrode is formed on a transparent second substrate so as to be opposed to the reflective electrode in common, and liquid crystal is sealed between the first and second substrates, and the plurality of switching elements are sequentially driven. Then, by holding the video signal as an electric charge in the storage capacitor connected to the switching element, the orientation of the liquid crystal between the reflective electrode connected to the switching element and the counter electrode is controlled in units of the reflective electrode, Counter electrode and In a reflective liquid crystal display element that modulates light that is transmitted through a crystal, incident on a reflective electrode, reflected, and transmitted through a liquid crystal and a counter electrode and then emitted to the outside, the light passes through a gap between adjacent reflective electrodes. A metal wiring for electrically connecting the switching element and the reflective electrode is formed on the insulating film adjacent to the first light-shielding film that shields light entering the direction of the switching element with a predetermined gap. In addition, a second light-shielding film is provided in a gap between the first light-shielding film on the insulating film and the metal wiring with a light-shielding insulating film having a predetermined thickness interposed therebetween.

  In the present invention, since the second light-shielding film is disposed on the insulating film with the insulating film having a predetermined thickness interposed between the first light-shielding film and the metal wiring, the second light-shielding film is the first light-shielding film. Compared to the conventional structure in which two light shielding films are arranged so as to overlap in the vertical direction while maintaining the function of shielding the light entering the direction of the switching element through the gap between the light shielding film and the metal wiring Thus, a structure in which an overlap area between two adjacent light shielding films on the insulating film can be reduced can be achieved.

  According to a second aspect of the present invention, in order to achieve the above object, the thickness of the light shielding insulating film between the first light shielding film and the metal wiring, and between the second light shielding film and the metal wiring. Each of the light-shielding insulating films has a thickness of less than 400 nm. Since the reflective liquid crystal display device reflects the light having a wavelength of 400 nm to 700 nm in the visible light region to perform color display, it is not necessary to use light in the ultraviolet region having a shortest wavelength of less than 400 nm in the visible light region. If the film thickness of the light-shielding insulating film is set to less than 400 nm, the light wave incident on the light-shielding insulating film is absorbed or reflected by the metal in the left-right direction, so that the light-shielding effect is maximized. it can.

According to a third aspect of the present invention, there is provided a method of manufacturing a liquid crystal display device, wherein the reflective electrode for reflecting incident light, the switching device connected to the reflective electrode, and the holding device connected to the switching device are provided. A plurality of pixels made up of capacitors are regularly arranged on the first substrate, a first light-shielding film is formed between the reflective electrode and the switching element via an insulating film, and the first The counter electrode is formed on the transparent second substrate so as to be commonly opposed to the plurality of reflective electrodes on the substrate, and liquid crystal is sealed between the first and second substrates. By sequentially driving the switching elements and holding the video signal as electric charges in the storage capacitor connected to the switching elements, the orientation of the liquid crystal between the reflective electrode connected to the switching element and the counter electrode is reflected by the reflective electrode. Control by unit Is transmitted through the counter electrode and a liquid crystal is reflected and incident on the reflective electrode, in the method of manufacturing a reflective liquid crystal display device for modulating light emitted to the outside through the liquid crystal and the counter electrode in the reflective electrode units,
A first light-shielding film that shields light entering the direction of the switching element through the gap between adjacent reflective electrodes; and the switching element and the reflective electrode adjacent to the first light-shielding film with a predetermined gap. A first step of forming a metal wiring for electrically connecting the two on the insulating film, and a second step of covering the first light-shielding film on the insulating film and the metal wiring with the first light-shielding insulating film. A first light-shielding insulating film coated in the second step and the second light-shielding film, and then removing the upper portion of the second light-shielding film to form a first light-shielding film on the insulating film, And a third step of leaving a second light-shielding film with a first light-shielding insulating film having a predetermined thickness interposed between the metal wiring and the metal wiring.

  In order to achieve the above object, the fourth invention further includes a fourth step of covering the upper surface of the element of the third step with the second light-shielding insulating film in addition to the step of the third invention, A fifth step of forming a connection hole facing the upper surface of the metal wiring by patterning and etching each of the first and second light shielding insulating films, a sixth step of filling the connection hole with a metal material, and a sixth step And a seventh step of forming a reflective electrode electrically connected to the metal wiring through the metal material of the connection hole on the upper surface of the obtained element.

  In the present invention, since the second light-shielding film is disposed on the insulating film with the insulating film having a predetermined thickness interposed between the first light-shielding film and the metal wiring, the second light-shielding film is the first light-shielding film. Compared to the conventional structure in which two light shielding films are arranged so as to overlap in the vertical direction while maintaining the function of shielding the light entering the direction of the switching element through the gap between the light shielding film and the metal wiring In addition, a liquid crystal display element having a structure in which an overlap area between two adjacent light shielding films on the insulating film can be reduced can be manufactured.

  According to the present invention, the second light-shielding film is disposed on the insulating film by disposing the second light-shielding film with the insulating film having a predetermined thickness in the gap between the first light-shielding film and the metal wiring. Compared to the conventional structure in which two light shielding films are arranged so as to overlap in the vertical direction while maintaining the function of shielding the light entering the direction of the switching element through the gap between the one light shielding film and the metal wiring Thus, since the overlap area between the two light shielding films adjacent in the horizontal direction on the insulating film can be reduced, the influence of dust and the like is reduced, and the first light shielding film and the second made of metal are reduced. Yield reduction due to short-circuiting of the light shielding film can be suppressed, and the cost can be reduced. In addition, since it is more resistant to light leakage than the conventional structure, flicker and image sticking can be reduced, and high reliability can be achieved.

  In addition, according to the present invention, light leakage can be reduced and satisfactory characteristics can be satisfied even with a small pixel area, so that the pixel can be miniaturized. In addition, since many pixels can be packed, high definition can be realized, and the display device can be greatly improved in performance.

  Further, according to the present invention, when a reflective liquid crystal display element having the same number of pixels as in the prior art is produced, the screen size can be reduced, so that the chip size is reduced. For example, the reflective type cut out from one wafer size Since the number of liquid crystal display element chips increases, the cost can be significantly reduced.

  Furthermore, according to the present invention, when a reflective liquid crystal display element having the same number of pixels as in the prior art is produced, the screen size of the reflective liquid crystal display element can be reduced, and as a result, the optical system and the lamp can be reduced. This makes it possible to reduce the size, cost and weight of the projector system at the same time, thus enabling a significant increase in performance.

  Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view per pixel of an embodiment of a liquid crystal display device according to the present invention. In the figure, the same components as those in FIG. In FIG. 1, pixel transistors 10 having a MOS type FET structure, which are switching elements formed in a well 22 on the surface of a silicon substrate 21, are arranged in a two-dimensional matrix corresponding to the pixel arrangement and cover the pixel transistors 10. A first metal 26 made of aluminum (Al) arranged in a two-dimensional matrix corresponding to the pixel arrangement is formed on the first interlayer film 25. Further, a diffusion layer 23 is formed in a region different from the well 22 on the surface of the silicon substrate 21, and a polysilicon layer 24 is formed on the diffusion layer 23 via an oxide film. A storage capacitor 11 is configured. Each element is separated by a field oxide film 43.

  The first metal 26 is electrically connected to the source 10 c of the pixel transistor 10 and the polysilicon layer 24 of the storage capacitor 11 through the opening (connection hole) of the first interlayer film 25. The first metal 26 is electrically connected to the drain 10 b of the pixel transistor 10 through another opening (connection hole) of the first interlayer film 25. However, the drain 10b, the source 10c, and the polysilicon layer 24 are not electrically connected. Although not shown in FIGS. 7 and 8, an antireflection film 44 made of TiN or the like with a predetermined thickness is formed on the surface of the first metal 26. Further, the first interlayer film 25 and the antireflection film 44 are covered with the second interlayer film 27. The above structure is the same as that of a conventional liquid crystal display element.

  In the present embodiment, the first metal light-shielding film 28 and the metal wiring 40 are formed on the second interlayer film 27 with a predetermined gap therebetween, and the first metal light-shielding film 28 and the metal wiring 40 are formed. A second metal light-shielding film 41 is formed in the gap with a light-shielding insulating film (third interlayer film) 29 interposed therebetween. The first metal light-shielding film 28, the second metal light-shielding film 41, and the metal wiring 40 are covered with a light-shielding insulating film 29, and the reflective electrode 13 is formed thereon. The reflective electrode 13 is electrically connected to the metal wiring 40 via a connection portion 42 that is a via hole (connection hole) formed in the light shielding insulating film 29, and the metal wiring 40 is further connected to the pixel transistor 10 via the first metal 26. Are electrically connected to the source 10c. That is, the metal wiring 40 is provided between the second metal light-shielding films 41 in order to electrically connect the reflective electrode 13 and the source 10 c of the pixel transistor 10.

  Although not shown in FIGS. 7 and 8, antireflection films 45 and 46 made of Ti, TiN or the like with a predetermined film thickness are formed on the upper and lower surfaces of the first metal light-shielding film (second metal) 28. Has been. Antireflection films 47, 48, and 49 made of Ti, TiN, or the like with a predetermined thickness are also formed on the upper and lower surfaces of the metal wiring 40 and the lower surface of the reflective electrode (third metal) 13.

  In the present embodiment, the light shielding insulating film 29 usually uses an oxide film, the film thickness of the light shielding insulating film 29 between the first metal light shielding film 28 and the second metal light shielding film 41, the metal wiring 40 and the second metal. The film thickness of the light-shielding insulating film 29 between the light-shielding films 41 is set to less than 400 nm, which is less than the wavelength of the color light incident on the substrate (for example, 100 nm). That is, the reflective liquid crystal display device performs color display by reflecting light having a wavelength of 400 nm to 700 nm in the visible light region. Accordingly, since it is not necessary to use ultraviolet light having a shortest wavelength less than 400 nm in the visible light region, it is not necessary to make light having a wavelength less than 400 nm incident on the liquid crystal panel. Here, if the thickness of the light shielding insulating film 29 is set to less than 400 nm, the light wave incident on the light shielding insulating film 29 is absorbed or reflected by the metal in the left-right direction. The light shielding effect can be maximized. Naturally, since the first metal light-shielding film (second metal) 28 and the second metal light-shielding film 41 need to be insulated, the film thickness is set in a range of less than 400 nm in oxide thickness in consideration of the yield.

  Further, the light shielding insulating film 29 is a film in which in-plane variation of the wafer is suppressed as is well known in order to form the film by applying the CVD method. Accordingly, the thickness of the light shielding insulating film 29 between the first metal light shielding film 28 and the second metal light shielding film 41 and the thickness of the light shielding insulating film 29 between the metal wiring 40 and the second metal light shielding film 41 are relatively uniform. Can be set. Therefore, it can be manufactured with little variation in light shielding effect. For this reason, most of the light incident on the pixel transistor 10 from the reflective electrode 13 can be cut, and leakage current due to the light can be prevented.

  In the present embodiment, the second metal light shielding film 41 is formed using tungsten. Usually, tungsten is used as a connection hole for connecting metal to metal. Usually, the connection hole is formed by a narrow hole, and tungsten is suitable for being embedded in the connection hole, and is generally used as a known technique. Therefore, it is suitable for forming in a narrow portion such as a gap between the first metal light shielding film 28 and the metal wiring 40. Further, since tungsten is a metal, it does not transmit light and has an excellent light shielding effect.

  Further, according to the structure of the present embodiment, compared with the overlap area between two metal light shielding films in the vertical direction in the conventional liquid crystal display element described in Japanese Patent Application Laid-Open No. 2004-206108, FIG. Since the overlap area in the horizontal direction between the first metal light-shielding film 28 and the metal wiring 40 can be reduced, the influence of dust and the like is reduced, and the probability of short-circuiting between the first metal light-shielding film 28 and the metal wiring 40 is reduced. It is possible to improve the yield.

  Here, considering the light incident path, the light incident from the upper part of the gap between the two adjacent reflective electrodes 13 is antireflective on the antireflection film 49 on the lower surface of the reflective electrode 13 and on the upper surface of the first metal light shielding film 28. Multiple reflection between the film 45 and the first metal light-shielding film 28 and the metal wiring 40 is repeated to reach the diffusion electrodes (drain 10b, source 10c) of the pixel transistor 10 and cause light leakage. That is, if only the gap between the first metal light shielding film 28 and the metal wiring 40 is shielded, light does not reach the diffusion electrode of the pixel transistor 10.

  Therefore, unlike the conventional liquid crystal display elements described in JP-A-2002-40482 and JP-A-2004-206108, the first metal light-shielding film 28 can be obtained without overlapping the two metal light-shielding films in the vertical direction. Light leakage can be prevented by shielding only the gap between the metal wiring 40 and the metal wiring 40. Therefore, in the present embodiment, the second metal light-shielding film 41 is formed in the gap between the first metal light-shielding film 28 and the metal wiring 40, thereby maintaining the function of preventing the above-described light leakage and in the vertical direction. Compared to the conventional liquid crystal display element in which two metal light shielding films overlap each other, the two first metal light shielding films 28 and the second metal light shielding film 41 are adjacent to each other in the horizontal direction. Can be reduced.

  Thereby, according to the present embodiment, the area affected by dust or the like is reduced, the probability of short-circuiting by the two metal light shielding films 28 and 41 can be reduced, and the yield can be improved. Furthermore, according to the present embodiment, since light leakage can be reduced, there is a feature that flicker and burn-in can be reduced, and high performance and high reliability can be achieved.

  In addition, according to the present embodiment, light leakage can be reduced and satisfactory characteristics can be satisfied even with a small pixel area, so that the pixel can be miniaturized. Since more pixels can be packed than in the past, higher definition can be realized, and the performance of the display element can be greatly improved.

  Further, according to the present invention, when a reflective liquid crystal display element having the same number of pixels as in the prior art is manufactured, the screen size can be reduced, so that the chip size is reduced. For example, the reflective type cut out from one wafer size Since the number of liquid crystal display element chips increases, the cost can be significantly reduced and the screen size can be reduced. This makes it possible to reduce the size of the optical system, lamp, etc. Because cost reduction and weight reduction are possible at the same time, significant performance improvement is possible.

  The second metal light shielding film 41 may be formed of aluminum. In this case, when the aluminum of the second metal light shielding film 41 is sputtered at a high temperature (about 400 ° C.), the aluminum flows and is buried in the gap between the first metal light shielding film 28 and the metal wiring 40 via the light shielding insulating film 29. It becomes easy. In addition, since aluminum generally has a low light transmittance as compared with tungsten, aluminum has a feature that it has better light shielding performance than tungsten. As a result, light leakage can be reduced as compared with the conventional structure. Therefore, flicker and burn-in can be reduced, and high performance and high reliability can be achieved.

  Next, the manufacturing method of the liquid crystal display element of this invention is demonstrated. FIG. 2 is a cross-sectional view of an essential element in each manufacturing process of an embodiment of a method for manufacturing a liquid crystal display element according to the present invention. In the figure, the same components as those in FIG. As shown in FIG. 2A, the first metal light shielding film 28 and the metal wiring 40 are formed on the silicon substrate 21 of FIG. 1 by a known method. Both the first metal light-shielding film 28 and the metal wiring 40 are made of aluminum (Al), and are formed on the second interlayer film 27 with a predetermined gap therebetween. Antireflection films 45 and 46 made of TiN are formed on the upper and lower surfaces of the first metal light shielding film 28, and antireflection films 47 and 48 made of TiN are formed on the upper and lower surfaces of the metal wiring. Is formed. These antireflection films 45 to 48 are formed together by a sputtering apparatus or the like when the first metal light shielding film 28 and the metal wiring 40 are formed. The antireflection films 45 to 48 may be made of Ti.

  Next, as shown in FIG. 2B, a CVD method is applied to the upper surface of the element of FIG. 2A to coat the oxide film 51 having a thickness of 100 nm, and then the CVD method is applied to the upper surface of the oxide film 51. Is applied to form a tungsten layer 52. Subsequently, portions of the tungsten layer 52 other than the tungsten layer portion formed in the gap between the first metal light shielding film 28 and the metal wiring 40 are removed by CMP (Chemical Mechanical Polishing). As a result, as shown in FIG. 2C, the tungsten layer 52 remains in a state of being embedded in the gap between the first metal light shielding film 28 and the metal wiring 40, and this forms the second metal light shielding film 41.

  Subsequently, a CVD method is applied to the upper surface of the element shown in FIG. 2C to form an oxide film 53 with a film thickness of 600 nm as shown in FIG. Subsequently, as shown in FIG. 2E, a connection hole 54 having a predetermined diameter for connecting the reflective electrode 13 is formed by patterning and etching so as to face the upper portion of the metal wiring 40 and the oxide films 51 and 53. The antireflection film 47 is removed and formed.

  Subsequently, after a tungsten layer is formed on the upper surface of the element of FIG. 2E by the CVD method or the like, only the tungsten layer in the connection hole 54 is formed by etch back or CMP as shown in FIG. The tungsten layer is removed leaving. The tungsten layer in the connection hole 54 becomes the connection portion 42. Then, TiN and aluminum are sequentially formed on the upper surface of the element shown in FIG. 5F by sputtering, and then, as shown in FIG. 2G by patterning and etching, an antireflection film 49 is formed on the reflective electrode 13 and its lower surface. Form. In this way, the main part of the present embodiment is manufactured.

  Note that an aluminum layer may be formed instead of the tungsten layer 52 as described above. When aluminum is sputtered at a high temperature (about 400 ° C.), the aluminum flows and is easily embedded in the gap between the first metal light shielding film 28 and the metal wiring 40 via the oxide film 51. In the step of FIG. 2C, a tungsten layer formed in the gap between the first metal light shielding film 28 and the metal wiring 40 among the tungsten layers formed on the top of the element by using etch back instead of CMP. Other than the above may be removed. At this time, etching back is performed by using anisotropic etching such as reactive ion etching (RIE), and the tungsten layer is etched from the upper surface. The anisotropic etching is set so that the etching is finished when most of the tungsten layer is eliminated by the end point, so that the tungsten layer is formed only in the gap between the first metal light shielding film 28 and the metal wiring 40. .

  Further, aluminum may be used for the second metal light shielding film 41, and etch back may be used. Since the etching is usually used for forming the aluminum pattern, the etching back of the aluminum can be easily performed.

  Next, the configuration of the reflective liquid crystal display element of this embodiment will be described. FIG. 3 shows a perspective view of an example in which a transparent substrate is superimposed on a drive circuit board. In the figure, a drive circuit board 61 corresponds to the silicon substrate 21 of FIG. 1, and a plurality of pixels having the structure shown in FIG. 1 are arranged on the drive circuit board 61 in a two-dimensional matrix. The pixel region 62 and the shift register circuit 63 including the horizontal shift register circuit 2 and the vertical shift register circuit 3 shown in FIG. 5 are created. A seal region 64 is provided on the drive circuit board 61 outside the shift register circuit 63, and a seal material and spacer balls are applied. The gap between the drive circuit substrate 61 and the transparent substrate 67 inside the seal region 64 is filled with a liquid crystal composition. The pixel region 62 has a spacerless structure in which a liquid crystal gap is created in the seal region 64 without using a spacer.

  On the other hand, the counter electrode 12 shown in FIG. 1 is formed on the transparent substrate 67, and a conductive paste is deposited on the counter contact 65 formed on the drive circuit substrate 61, and the transparent electrode 67 is transparent. When the substrate 67 and the drive circuit substrate 61 are bonded and fixed with a sealing material, they are connected. The counter contact 65 is wired to the external connection terminal 66, and a predetermined voltage can be applied from the external connection terminal 66. The drive circuit substrate 61 and the transparent substrate 67 are bonded and fixed with a sealing material to form a liquid crystal display element.

  Next, as shown in FIG. 4, a flexible printed wiring board 68 for supplying a signal from the outside to the liquid crystal display element of FIG. 3 is connected to the external connection terminal 66 to complete the liquid crystal display element. External signals (video signal and control signal) are input from an external input terminal 69 provided on the flexible printed wiring board 68.

  This reflective liquid crystal display element is formed on an active matrix circuit in which a plurality of pixel transistors and reflective electrodes whose potentials are controlled by the pixel transistors are arranged on a drive circuit substrate 61, and a film is formed on a transparent substrate (glass substrate or the like) 67. And a counter electrode (common electrode) and a liquid crystal sealed between the active matrix circuit and the counter electrode.

It is a longitudinal cross-sectional view per pixel of one Embodiment of the liquid crystal display element of this invention. It is principal part element sectional drawing in each manufacturing process of one Embodiment of the manufacturing method of the liquid crystal display element of this invention. It is a perspective view of an example which laminated the transparent substrate on the drive circuit board. It is a figure of the liquid crystal display element with which the flexible printed wiring board was connected to the external connection terminal. It is a block block diagram of an example of the active matrix circuit of a reflection type LCD panel. It is a cross-sectional schematic diagram of an example of 1 pixel of the pixel part in FIG. It is a cross-sectional schematic diagram which shows the incident path | route of the light in 1 pixel of the pixel part shown in FIG. It is a cross-sectional schematic diagram of an example of 1 pixel of the conventional liquid crystal display element of Unexamined-Japanese-Patent No. 2004-206108.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pixel part 2 Horizontal shift register circuit 3 Vertical shift register circuit 10 Pixel transistor 10a Gate 10b Drain 10c Source 11 Holding capacity 12 Counter electrode 13 Reflective electrode 23 Diffusion layer 24 Polysilicon layer 25 First interlayer film 26 First metal 27 Second Interlayer film 28 First metal light shielding film (second metal)
29 Light-shielding insulating film (third interlayer film)
30 Liquid crystal 40 Metal wiring 41 Second metal light shielding film 42 Connection portion 52 Tungsten layer 54 Connection hole

Claims (5)

A plurality of pixels each including a reflective electrode that reflects incident light, a switching element connected to the reflective electrode, and a storage capacitor connected to the switching element are regularly arranged on the first substrate. A first light-shielding film is formed between the reflective electrode and the switching element via an insulating film, and a counter electrode is commonly opposed to the plurality of reflective electrodes on the first substrate. Is formed on a transparent second substrate, and liquid crystal is sealed between the first and second substrates, and the plurality of switching elements are sequentially driven and connected to the switching elements. By holding the video signal as a charge in the storage capacitor, the orientation of the liquid crystal between the reflective electrode connected to the switching element and the counter electrode is controlled in units of the reflective electrode, and the counter electrode and the liquid crystal are transmitted. In the reflection type liquid crystal display device wherein incident on the reflective electrode reflects, to modulate the light emitted to the outside through the liquid crystal and the counter electrode in the reflective electrode units Te,
The switching element and the reflective electrode are electrically connected to each other with a predetermined gap adjacent to the first light shielding film that shields light entering the direction of the switching element through the gap between the adjacent reflective electrodes. A metal wiring for connection is formed on the insulating film, and a light-shielding insulating film having a predetermined thickness is sandwiched between the first light-shielding film and the metal wiring on the insulating film. A liquid crystal display element comprising a second light shielding film.   The thickness of the light shielding insulating film between the first light shielding film and the metal wiring and the thickness of the light shielding insulating film between the second light shielding film and the metal wiring are each less than 400 nm. The liquid crystal display element according to claim 1, wherein the liquid crystal display element is provided.   The liquid crystal display element according to claim 1, wherein the second light shielding film is formed of tungsten or aluminum. A plurality of pixels each including a reflective electrode that reflects incident light, a switching element connected to the reflective electrode, and a storage capacitor connected to the switching element are regularly arranged on the first substrate. A first light-shielding film is formed between the reflective electrode and the switching element via an insulating film, and a counter electrode is commonly opposed to the plurality of reflective electrodes on the first substrate. Is formed on a transparent second substrate, and liquid crystal is sealed between the first and second substrates, and the plurality of switching elements are sequentially driven and connected to the switching elements. By holding the video signal as a charge in the storage capacitor, the orientation of the liquid crystal between the reflective electrode connected to the switching element and the counter electrode is controlled in units of the reflective electrode, and the counter electrode and the liquid crystal are transmitted. The method of manufacturing a reflection type liquid crystal display device wherein incident on the reflective electrode reflects, to modulate the light emitted to the outside through the liquid crystal and the counter electrode in the reflective electrode units Te,
The first light-shielding film that shields light entering the direction of the switching element through the gap between the adjacent reflective electrodes, and the switching adjacent to the first light-shielding film with a predetermined gap. A first step of forming, on the insulating film, a metal wiring for electrically connecting an element and the reflective electrode;
A second step of covering the first light shielding film on the insulating film and the metal wiring with the first light shielding insulating film;
The first light-shielding insulating film coated in the second step is covered with a second light-shielding film, and then the second light-shielding film is removed to remove the first light-shielding film on the insulating film. And a third step of leaving the second light-shielding film in the gap between the film and the metal wiring with the first light-shielding insulating film having a predetermined thickness interposed therebetween. Method. A fourth step of covering the upper surface of the element of the third step with a second light-shielding insulating film;
A fifth step of forming a connection hole facing the upper surface of the metal wiring by patterning and etching the first and second light shielding insulating films, respectively;
A sixth step of filling the connection hole with a metal material;
And a seventh step of forming the reflective electrode electrically connected to the metal wiring via the metal material of the connection hole on the upper surface of the element obtained by the sixth step. The manufacturing method of the liquid crystal display element of Claim 4.

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