JP4057044B2 - Manufacturing method of electronic equipment - Google Patents

Description

  The present invention relates to an active matrix panel having a pixel portion having a plurality of pixel electrodes, an electronic device such as a mobile phone or a personal computer provided with the pixel portion, and a manufacturing method thereof.

  In information systems, flat displays such as liquid crystal panels that convert electric signals (image signals) into optical signals for display are drawing attention. In order to perform full color display or moving image display, a matrix driving method is adopted as a display method of these flat displays.

  FIG. 9 shows a cross-sectional view of a pixel portion of a conventional reflective active matrix liquid crystal display. FIG. 9 corresponds to a cross-sectional view of a so-called TFT substrate. A thin film transistor (TFT) 2 is formed for each pixel on a substrate 1 having an insulating surface. The TFT 2 has an active layer 3, a gate insulating film 4, a gate electrode 5, a source electrode 6 connected to the source / drain region of the active layer 3, and a drain electrode 7.

  The gate electrode 5, the source electrode 6, and the drain electrode 7 are insulated and separated by the first interlayer insulating film 8. A second interlayer insulating film 11 is provided so as to cover the source electrode 6 and the drain electrode 7. A black matrix 12 is formed on the second interlayer insulating film 11, and a third interlayer insulating film 13 is formed so as to cover the black matrix 12. The pixel electrode (reflection electrode) 14 is connected to the drain electrode 7 of the TFT 2 through a contact hole formed in the second and third interlayer insulating films 11 and 13.

  Through steps such as alignment film formation and rubbing treatment, the substrate on which the counter electrode is formed and the element substrate shown in FIG. 9 are bonded together. A liquid crystal material is sealed between the substrates, and the cell set of the reflective liquid crystal display device is completed.

  In FIG. 9, the black matrix 12 is illustrated as being divided, but is integrally formed on the interlayer insulating film 11 in a lattice shape so as to close the gap 20 between the adjacent pixel electrodes 14. The black matrix 12 blocks light incident from the gap 20 between the pixel electrodes.

  In recent years, in the market of display devices such as HDTV (high-definition television), SXGA display, and photographic negative reading device, there has been a demand for a larger number of pixels and a higher density. However, as the pixel pitch is miniaturized, the ratio of the gap between the adjacent pixel electrodes becomes relatively wide, so the problem due to the gap between the pixel electrodes cannot be ignored.

  The first problem due to the gap between the pixel electrodes is that, in the reflective panel of the conventional example of FIG. 9, the black matrix 12 is usually formed of a metal material. Therefore, when the incident light 30 enters from the gap 20 between the pixel electrodes, this light may be irregularly reflected by the black matrix 12 and further by the pixel electrode 14. When such irregularly reflected light 31 (illustrated by arrows) is applied to the TFT 2, the TFT 2 is deteriorated or crosstalk occurs. Further, if the light is mixed into the light reflected by the pixel electrode 14 as in the case of irregularly reflected light 32 (illustrated by an arrow), there arises a problem that the contrast is lowered, particularly the black level is lowered.

  Second, in the case of a liquid crystal display device, the alignment of liquid crystal molecules is disturbed at the stepped portion of the gap 20 of the pixel electrode. In the transmissive panel, since the cell gap is relatively thick as 7 to 10 μm, the ratio of the step (the thickness of the pixel electrode) in the cell gap is small, and the disturbance of the orientation does not have a great influence on the display.

  However, the cell gap of the reflective liquid crystal panel is about 2 to 4 μm, and the cell gap of the ferroelectric / antiferroelectric liquid crystal panel is 2 μm or less to solve the spiral of liquid crystal molecules, which is very narrow compared to the transmissive type. . Therefore, in these liquid crystal panels, since the ratio of the step difference in the cell gap is increased, the influence of the disturbance of the liquid crystal molecules is increased, which causes a decrease in contrast.

  An object of the present invention is to solve the above-described problems, and provide an electronic device including a pixel portion that has a long life and high reliability and can display a high image quality, and a manufacturing method thereof.

According to a method for manufacturing an electronic device of the present invention for solving the above-described problem, a first interlayer insulating film that covers a plurality of transistors is formed, a wiring is formed over the first interlayer insulating film, and the first A second interlayer insulating film is formed on the interlayer insulating film to cover the wiring, a conductive film is formed on the second interlayer insulating film, a resist is formed on the conductive film, and the resist is masked. By etching the conductive film, a plurality of pixel electrodes are formed so that a gap between adjacent pixel electrodes and the wiring overlap, and the second interlayer insulating film is etched using the resist as a mask. Thus, a groove is formed at a position overlapping the gap and the wiring, an insulating light absorber is formed in the groove and on the resist mask surface, and the light absorber and the resist are etched. By removing the resist, only the resist remains, and the light absorber is processed into a shape protruding from the surface of the pixel electrode. It is characterized by doing.

In the present invention, the light absorber is characterized by comprising an oxidation coating film in which a pigment or a carbon-based material is dispersed.

In the present invention, the light absorber is made of an organic resin in which a pigment or a carbon-based material is dispersed.

In the present invention, the light absorber is made of acrylic, polyimide, polyamide, polyamideimide, or epoxy in which a pigment or a carbon-based material is dispersed.

  In the present invention, the light absorbing material is buried in the groove formed in the gap between the pixel electrodes, so that it is possible to completely prevent light from entering through the gap between the pixel electrodes. In particular, when the pixel electrode is formed of a metal film, light can be completely blocked by the pixel electrode and the light absorber, so that the active element can be prevented from being deteriorated in light and crosstalk can be prevented.

  In addition, the groove portion in which the light absorber of the present invention is embedded is formed in a self-aligned manner, and further, the manufacturing method is simplified because the patterning process of the light absorber is unnecessary, and the aperture ratio of the pixel region is not impaired. can do.

  This embodiment will be described with reference to FIG. FIG. 1A is a front view of a pixel portion of this embodiment, and FIG. 1B is a cross-sectional view taken along line A-A ′ in FIG.

  As shown in FIG. 1B, a TFT is formed on the substrate 100 as an active element for each pixel. The TFT includes an active layer having a source region 107, a drain region 108, and a channel formation region 109, a gate insulating film 102 covering the active layer, a gate electrode 105, a source electrode 111, and a drain electrode 113.

  An interlayer insulating film 114 is formed so as to cover these TFTs. The drain electrode 113 of the TFT and the pixel electrode 115 are connected via the interlayer insulating film 114. A groove portion is formed in the interlayer insulating film 114 at a portion overlapping the gap between adjacent pixel electrodes 115. The light absorber 122 is embedded in the gap between the groove and the pixel electrode 115, and the light absorber 122 is integrally provided in a lattice shape as shown in FIG.

  In order to form the light absorber 122, as shown in FIG. 5A, the interlayer insulating film 114 is removed by etching so that the gaps between the adjacent pixel electrodes 115 and the gaps overlap each other, thereby forming the groove 120. By causing the pixel electrode 115 to function as an etching mask, the groove 120 is formed in a self-aligned manner, and the end surface (divided cross section) of the pixel electrode 115 and the side surface of the groove 120 of the interlayer insulating film 114 are formed in substantially the same plane. Is done.

  Next, as shown in FIG. 5B, an insulating light absorber 121 is formed so as to be embedded in the gap between the groove 120 of the interlayer insulating film 114 and the pixel electrode and to cover the surface of the plurality of pixel electrodes 115. . Next, the light absorbing material 121 covering the surface of the pixel electrode 115 is removed by dry etching or CMP, and the surfaces of the plurality of pixel electrodes 115 are exposed as shown in FIG. The portion remaining in the groove portion of the interlayer insulating film 114 and the gap between the pixel electrodes 115 functions as the light absorber 122 in FIG.

  In the present embodiment, the groove in which the light absorber 122 is formed is formed in a self-aligned manner, and the patterning process of the light absorber 122 is unnecessary, so that the manufacturing process is simple. The light absorber 122 can be formed without reducing the area (aperture ratio) of the pixel electrode 115.

  In the present embodiment, the light absorber 122 is present at least in the groove formed in the interlayer insulating film 114. The light absorbing material 122 in the groove portion of the interlayer insulating film 114 absorbs the light incident from the gap of the pixel portion 115 and does not reflect or transmit it. Accordingly, when the pixel electrode 115 is formed of a metal material, light can be completely shielded by the pixel electrode 115 and the light absorber 122, so that light degradation of the TFT can be prevented and crosstalk can also be prevented.

  By embedding the light absorber 122 in the groove portion of the interlayer insulating film 114 and the gap between the pixel electrodes 115, the step portion of the pixel electrode 115 is lowered. For example, when the pixel portion of the present invention is applied to a liquid crystal panel, disorder of the alignment of liquid crystal molecules at the step portion of the pixel electrode 115 can be suppressed. More preferably, the surface of the pixel electrode 115 and the surface of the light absorber 122 are substantially coplanar. Thereby, the alignment state of the liquid crystal molecules is made uniform between the substrates, and disclination can be prevented.

  Further, the light absorber 122 can be protruded from the pixel electrode. This makes it difficult for the liquid crystal molecules arranged on the light absorber 112 to respond to the electric field generated by the pixel electrode 115 and the counter electrode, so that the response of the liquid crystal molecules on the pixel electrode 115 contributing to display is not disturbed. Image quality display is possible.

The light absorber 122 is formed of a colored insulating material that absorbs light. A coating film that can be formed by a spin coat method is suitable for the light absorber because it fills the fine groove portion of the gap between the pixel electrodes 115. As such a coating film, an organic resin selected from acrylic, polyimide, polyamide, polyimide amide, and epoxy, or a silicon oxide-based coating film such as PSG or SiO ₂ can be used. In order to color these insulating materials, a pigment or a carbon-based material is dispersed in the insulating material.

  Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS.

  In this embodiment, an example in which the present invention is applied to a reflective liquid crystal display device will be described. FIG. 1 is a configuration diagram of a pixel portion of this embodiment, FIG. 1A is a front view of the pixel portion, and FIG. 1B is a cross section taken along line AA ′ in FIG. FIG.

  In the pixel portion shown in FIG. 1, a TFT is formed as an active element for each pixel on a substrate 100 having an insulating surface. An interlayer insulating film 114 is formed so as to cover the TFT. The drain electrode 113 of the TFT and the pixel electrode 115 made of a metal material are connected via the interlayer insulating film 114. A groove portion is formed in the interlayer insulating film 114 so that a gap overlaps a gap between adjacent pixel electrodes 115. A light absorber 122 is embedded in the gap between the groove and the pixel electrode 115.

  As shown in FIG. 1A, light absorbers 122 are integrally provided in the gaps between the pixel electrodes 115 in a lattice shape to prevent light from entering through the gaps between the pixel electrodes 115. Hereinafter, a manufacturing process of the pixel portion illustrated in FIG. 1 will be described with reference to FIGS.

  A substrate 100 having an insulating surface is prepared. As the substrate 100, a glass substrate or a quartz substrate is used. In the case of using a glass substrate, a base insulating film made of silicon oxide for preventing diffusion of impurities such as Na ions is preferably formed on the surface.

  A TFT active layer 101 is formed on the substrate 100 for each pixel. In order to form the active layer 101, amorphous silicon having a thickness of 40 to 100 nm, here 50 nm, is formed into a polycrystal, and the polycrystallized silicon is separated into islands to form the active layer 101. Form. Then, boron is doped into the active layer 101 for threshold control. Next, a silicon oxide film functioning as the gate insulating film 102 is formed over the entire substrate. The thickness of the silicon oxide film is 120 nm.

  A conductive film constituting a gate electrode / wiring is formed on the gate insulating film 102. In this embodiment, an aluminum film to which a small amount of Sc is added is formed to a thickness of 400 nm. The gate electrode 104 and the gate wiring 105 are formed by patterning the aluminum film. The gate electrode 104 is formed integrally with the gate wiring 105 and extends from the wiring 105.

  Anodizing is performed using the gate electrodes / wirings 104 and 105 as anodes, and an anodized film 106 is formed on the surface. The anodic oxide film 106 has a function of electrically and physically protecting the gate electrodes / wirings 104 and 105. Note that the anodic oxide film 106 is omitted in FIG.

  Next, phosphorus ions are doped into the active layer 101 by ion doping. Since the gate electrode 104 serves as a mask, the source region 107, the drain region 108, and the channel formation region 109 are formed in a self-aligned manner. After the doping, the doped phosphorus is activated by laser irradiation or heat treatment, and at the same time, the active layer damaged by the doping is annealed.

  2A is a top view of the pixel portion, and FIG. 2B is a cross-sectional view taken along line A-A ′ in FIG. The subsequent steps will be described with reference to FIG. FIG. 3A is a top view of the pixel portion, and FIG. 3B is a cross-sectional view taken along line A-A ′ in FIG.

  As shown in FIG. 3B, a first interlayer insulating film 110 is formed. Here, a silicon nitride film having a thickness of 20 nm is formed by a plasma CVD method, and a silicon nitride oxide film having a thickness of 800 nm is continuously formed. Then, contact holes reaching the source / drain regions 107 and 108 are opened in the interlayer insulating film 110.

  Next, a laminated film of titanium film / aluminum film / titanium film is formed. The thickness of each titanium film is 100 nm, and the thickness of the aluminum film is 300 nm. The stacked film is patterned to form a source electrode 111, a source wiring 112, and a drain electrode 113, respectively. The source electrode 111 is formed integrally with the source wiring 112 and extends from the wiring 112. Through the above steps, the TFT of the pixel portion is completed.

  The subsequent steps will be described with reference to FIG. 4A is a top view of the pixel portion, and FIG. 4B is a cross-sectional view taken along line A-A ′ in FIG.

  As shown in FIG. 4B, a second interlayer insulating film 114 having a thickness of 1 to 2 μm is formed to cover the TFT. Here, an acrylic film having a thickness of 1.5 μm is formed as the interlayer insulating film 114.

The material of the interlayer insulating film 114 is preferably an organic resin film. Since the organic resin film can be formed by applying a solution by a spin coating method, it is possible to form a film with a flat surface by offsetting the unevenness of the lower part. Specifically, acrylic, polyimide, polyamide, polyimide amide, epoxy, or the like is used as the organic resin film. In addition to the organic resin, a silicon oxide-based coating film such as PSG or SiO ₂ can be used as the coating film.

  A contact hole reaching the drain electrode 113 is opened in the interlayer insulating film 114. Next, a metal film that forms the pixel electrode 115 is formed. An aluminum film is formed to a thickness of 200 to 400 nm, here a thickness of 300 nm by a sputtering method. Next, a resist mask 116 for patterning is formed on the aluminum film. The aluminum film is patterned using the mask 116 to form the pixel electrode 115. Note that the resist mask 116 is omitted in FIG.

  Each pixel electrode 115 is connected to the drain electrode 113 of the TFT for each pixel, and is arranged in a matrix with intervals Px and Py in the X direction and Y direction, respectively. The intervals Px and Py may be set only according to a design rule that maximizes the aperture ratio, and the intervals Px and Py can be set to about 1 to 3 μm. Here, the intervals Px and Py are 2 μm.

Next, as shown in FIG. 5, the groove 120 is formed in the second interlayer insulating film 114 in a self-aligning manner using the pixel electrode 115 as an etching mask. In order to form the groove 120, a dry etching method such as plasma etching or RIE (reactive ion etching) is used. In this embodiment, a plasma etching method is used, and a mixed gas of O ₂ and CF ₄ is used as an etching gas. The concentration of CF ₄ is 1 to 10% with respect to the total gas. The etching rate can be controlled by conditions such as CF ₄ concentration and pressure. In order to prevent the surface of the pixel electrode 115 from being altered by the etching gas, etching is performed with the resist mask 116 remaining to protect the pixel electrode 115.

Here, an etching gas having a CF ₄ concentration of 5% is used, and the second interlayer insulating film 114 in the gap between the pixel electrodes 115 is removed by a depth of about 1 μm by plasma etching to form the groove 120. In the cross-sectional view of FIG. 5A, the groove portions 120 are illustrated as being separated from each other. However, in actuality, the groove portions 120 are integrally formed in a lattice shape so as to overlap the gap between the pixel electrodes 115. Is done.

  Next, as shown in FIG. 5B, after the resist mask 116 is removed, an insulating layer 121 that fills the gap 120 and the gap between the adjacent pixel electrodes 115 and covers the surface of the pixel electrodes 115 is formed. In this embodiment, an acrylic resin in which a black pigment is dispersed is applied by a spin coating method and cured to form an insulating layer 121 made of black acrylic.

The depth of the groove 120 is 1 μm and the width is 2 μm. In order to fill such a fine lattice pattern with the insulator layer 121 in the entire pixel portion, the insulator layer 121 uses a coating film that can be formed from a solution. As such a coating film, an organic resin such as acrylic, polyimide, polyamide, polyimide amide, or epoxy is used. The acrylic used in this example has a feature that it has a relative dielectric constant lower than that of the liquid crystal material and is the cheapest among the listed resin materials. Further, as a film that can be formed from a solution, a silicon oxide-based coating film such as PSG or SiO ₂ can be used.

  Further, the black pigment is dispersed in order to give the insulator layer 121 the same light shielding function as that of the conventional black matrix, but a carbon-based material can also be dispersed. The pigment is not limited to black, and may be any color as long as the insulating layer 121 can absorb light.

Next, the insulating layer 121 covering the surface of the pixel electrode 115 is removed by a dry etching process such as O ₂ ashing, so that only the gaps between adjacent pixel electrodes 115 and the groove 120 are insulated as shown in FIG. The physical layer 121 is left. The remaining insulator layer 121 becomes the light absorber 122. In FIG. 1B, the light absorbers are illustrated as being separated from each other, but actually, as shown in FIG. 1A, the light absorber 122 fills the gap between the pixel electrodes 115 and forms a lattice shape. It is formed integrally.

In this embodiment, O ₂ ashing is used as a means for forming the light absorber 122. Considering that the ashing etching rate is typically about 0.3 to 1 μm / min, in FIG. 5B, the thickness t1 of the insulating layer 121 covering the pixel electrode 115 is 0.3 to 1 in FIG. It should be about 5 μm. The thickness of t ₁ can be controlled by the rotation speed of the spinner when forming the insulator layer 121, the viscosity of the raw material solution of the insulator layer 121, and the like.

Further, in order not to impair the reflectance of the pixel electrode 121, it is necessary to completely remove the insulating layer 121 covering the surface of the pixel electrode 115 in the O ₂ ashing. Before the insulating layer 121 covering the surface of the pixel electrode 115 is completely removed, at least the insulating layer 121 embedded in the groove 120 (the portion that becomes the light absorber 122 later) is not removed. the thickness t ₀ of the thickness t ₀ is obtained by adding the thickness of the groove 120 depth of the electrode 115, i.e., the light absorbing material 122 is thicker than the thickness t ₁ of the ashed the insulating layer 121. As a result, an etching margin can be ensured, and the gap between the pixel electrodes 115 and the insulating layer 121 embedded in the groove 120 can be prevented from being removed.

In FIG. 5B, t ₀ is 1.3 μm, which is the sum of the depth of the groove 120 of 1 μm and the pixel electrode thickness of 300 nm. Here, the thickness t ₁ of the insulator layer 121 to be removed is The thickness was 0.5 μm.

Note here, the groove 120 may be formed to have been formed in a concave shape on the insulating layer 114, through the insulator layer 114 to earn a depth t _0. In this case, since the groove 120 is formed along a lattice (see FIG. 4) formed by the gate wiring 105 and the source wiring 112, the surface of the source wiring 112 is exposed to the etching gas when it penetrates the insulator layer 114. In this case, the surface of the source wiring 112 needs to be made of a material that is not altered by the etching gas.

  Further, since the pixel electrode intervals Px and Py are about 1 to 3 μm, plasma hardly enters the gaps between the pixel electrodes 115 in the ashing process, and the insulating layer 121 at this portion is hardly removed. Therefore, the insulating layer 121 formed on the surface of the pixel electrode 115 can be removed by ashing, and the insulating layer 121 embedded in the gap and the groove 120 of the pixel electrode 115 can be left. This remaining insulator layer 121 corresponds to the light absorber 122 of FIG.

  In FIG. 1, the surface of the light absorber 122 and the pixel electrode 115 are shown to coincide with each other. However, as described above, it is necessary to completely remove the insulating layer 121 covering the surface of the pixel electrode 115 in O 2 ashing. is there. Therefore, in FIG. 6A, as indicated by 150, the insulating layer 121 in the gap between the pixel electrodes 115 may be partially removed. However, even when the surface of the light absorber 122 is lower than the surface of the pixel electrode 115 as shown in FIG. 5A, light passing through the gap between the pixel electrodes 115 can be blocked by the light absorber 122.

  That is, in order to block light passing through the gap between the pixel electrodes 115, at least the side surface and the bottom surface of the groove 120 may be covered with the light absorber 122. Therefore, in order to completely remove the insulating layer 121 covering the surface of the pixel electrode 115, the insulating layer 121 in the gap between the pixel electrodes 115 may be almost removed as indicated by 160 in FIG. 6B.

  After the light absorber 122 is formed and the pixel portion shown in FIG. 1 is completed, a reflective liquid crystal display device is completed by a known cell assembly process. The liquid crystal material is appropriately selected in accordance with the display mode such as paraelectric liquid crystal, ferroelectric liquid crystal, or anti-ferroelectric liquid crystal.

  In this embodiment, since the light absorber 122 is made of acrylic in which a black pigment is dispersed, light is not irregularly reflected on the surface. Accordingly, only light reflected by the pixel electrode 115 contributes to display, and display with high contrast can be performed.

  Further, since light does not pass through the light absorber 122 and the material of the pixel electrode 115 is metal, the pixel electrode 115 and the light absorber 112 can completely prevent the TFT from being irradiated with light. , Light deterioration can be prevented.

  Further, the step of the pixel electrode 115 can be reduced by embedding the light absorber 122 in the gap between the pixel electrodes 115. As a result, the disorder of the alignment of the liquid crystal molecules at the step portion of the pixel electrode 115 can be suppressed. This effect can be obtained not only by the reflective display device but also by the transmissive display device. In the case of a transmissive display device, it is necessary to form a black matrix that shields the active layer of the TFT in addition to the light absorber 122.

  In this embodiment, the groove in which the light absorber 122 is embedded is formed in a self-aligned manner, and the light absorber 122 does not require a patterning process, so that the process can be simplified. Further, it can be formed without impairing the aperture ratio.

  In the first embodiment, when the light absorber 122 is formed, a dry etching method is used as a means for removing the extra insulator layer 121 that covers the surface of the pixel electrode 115. In this embodiment, CMP (Chemical Mechanical Polishing) is used as means for removing the extra insulator layer 121.

  First, the structure shown in FIG. 5B is manufactured according to the same steps as in the first embodiment. Then, the excess insulating layer 121 covering the surface of the pixel electrode 115 is polished and removed by CMP. The CPM condition is that CMP is terminated when the surface of the pixel electrode 155 is exposed by setting the type of slurry and the number of rotations of the polishing cloth so that the insulating layer 121 is polished but the pixel electrode 155 is not polished as much as possible. Is possible.

  For this reason, the hardness difference between the surface of the pixel electrode 155 and the hardness of the insulating layer 121 is made as large as possible. For example, when the pixel electrode 155 is formed of an aluminum material as in the first embodiment, the surface may be oxidized by anodizing or the like to form alumina.

  FIG. 7 is an explanatory diagram of a manufacturing process of the light absorber of this example. In this example, another method for manufacturing a light absorber is described. FIG. 8 shows only a part of the TFT. In FIG. 7, the same reference numerals as those in FIGS. 1 to 5 denote the same members.

  First, the structure shown in FIG. 5A is manufactured according to the same steps as in the first embodiment. Then, as illustrated in FIG. 7A, the insulating layer 201 is formed in a state where the resist mask 116 for patterning the pixel electrode 115 is left. This insulator layer 201 will later constitute a light absorber and is made of a colored insulator material.

Also in this embodiment, as in the first embodiment, the insulating layer 201 is coated with an acrylic resin in which a black pigment is dispersed by a spin coating method, cured, and formed with black acrylic. This is because the gap between the groove 120 and the pixel electrode 115 is filled with the insulating layer 201. In addition to the acrylic resin, organic resins such as polyimide, polyamide, polyimide amide, and epoxy that can be prepared by a spin coating method, and silicon oxide-based coating films such as PSG and SiO ₂ can be used. Note that although the black pigment is dispersed in the insulator layer 201, a carbon-based material may be dispersed.

Next, the insulator layer 201 covering the surface of the pixel electrode 115 is removed by dry etching such as O ₂ ashing. Etching is continued, and the insulating layer 201 filled in the gap together with the resist mask 116 is also removed. Then, the etching is finished with the resist mask 116 remaining as thick as h. The thickness h can be controlled by the etching time.

  In the state of FIG. 7B, the insulating layer 201 filled in the gaps between the groove 120, the pixel electrode 115, and the gap between the resist masks 116 remains. This becomes the light absorber 202. Then, as shown in FIG. 7C, only the resist mask 116 is stripped with a dedicated stripping solution. As a result, the light absorber 202 is formed protruding from the surface of the pixel electrode 115.

  By causing the light absorber 202 to protrude from the surface of the pixel electrode 115, the liquid crystal molecules existing on the light absorber 202 (on the gap between the pixel electrodes 115) are difficult to respond to the action of the electric field created by the neighboring pixel electrodes 115. You can Since the liquid crystal molecules existing between the pixel electrodes 115 do not contribute to display, the response failure of the liquid crystal molecules existing on the pixel electrodes 115 can be prevented by preventing such liquid crystal molecules from responding, and high-quality display is possible. Become.

  7 is particularly effective when the etching rate of the insulator layer 201 and the resist mass resist mask 116 is substantially the same or when the etching rate of the insulator layer 201 is high, and the resist mask 116 is formed by the thickness h. By leaving, the light absorber 202 can protrude from the pixel electrode 115.

  On the other hand, both materials can be selected so that the etching rate of the resist mask 116 is higher than that of the insulating layer 201. In this case, etching is performed until the resist mask 116 is completely removed. When the etching is completed, the insulating layer 201 can protrude beyond the surface of the pixel electrode 115 due to the difference in etching rate. Further, whether or not the resist mask 116 is completely removed can be monitored by an etching apparatus, but the thickness h for leaving the resist mask 116 is controlled by time and cannot be monitored, so it is completely removed. This is more excellent in controllability and reproducibility than leaving the resist mask 116 to finish etching.

  In this embodiment, the light absorber 202 protrudes from the surface of the pixel electrode 115. However, the resist mask 116 is completely removed by extending the etching time, so that the surface of the light absorber 202 is the surface of the pixel electrode 115. Can be made almost the same. Further, as indicated by 150 and 160 in FIG. 6, etching may be performed to a state where the surface is depressed from the surface of the pixel electrode 115, and the light absorber 202 may be left at least in the groove 120 of the interlayer insulating film 114.

  Alternatively, after the structure shown in FIG. 7A is manufactured, the light absorber 202 can be formed by the CMP process described in Embodiment 2. In this case, the resist mask 116 may be polished and removed together with the insulating layer 201 to expose the surface of the pixel electrode 115.

  In the first to third embodiments, the active element in the pixel portion is a top gate type TFT, but is not limited to this structure, and may be a TFT having another structure such as a bottom gate type TFT. In addition to a TFT, a diode, an MIM element, or the like can be formed.

  In Examples 1 to 3, although insulating glass or quartz is used for the substrate 100, a single crystal silicon substrate can be used when a reflective pixel portion is formed. In this case, a MOS transistor may be formed on a single crystal silicon substrate as an active matrix element. By using a single crystal silicon substrate, light from the substrate surface can be blocked by the pixel electrode 115 and the light absorber 122, and light from the back surface of the substrate can also be blocked.

  FIG. 8 is a schematic external view of the electronic apparatus of this embodiment. In this embodiment, an application product of the electronic device of the present invention will be described. Examples of the electronic apparatus to which the present invention is applied include a video camera, a still camera, a projector, a head mounted display, a car navigation system, a personal computer, a personal digital assistant (mobile computer, mobile phone), and the like.

  FIG. 8A illustrates a mobile computer, which includes a main body 2001, a camera unit 2002, an image receiving unit 2003, operation switches 2004, and a reflective liquid crystal display device 2005.

  FIG. 8B illustrates a head-mounted display which includes a main body 2101, a pair of reflective liquid crystal display devices 2102, and a band portion 2103 for fixing the main body to the head. The pair of liquid crystal display devices display a left-eye image and a right-eye image, respectively. The user views this image through the optical system. Then, it can be seen as if a large screen is displayed in front of you.

  FIG. 8C illustrates a mobile phone, which includes a main body 2201, an audio output unit 2202, an audio input unit 2203, a reflective liquid crystal display device 2204, operation switches 2205, and an antenna 2206.

  FIG. 8D illustrates a video camera, which includes a main body 2301, a reflective liquid crystal display device 2302, an audio input unit 2303, operation switches 2304, a battery 2305, and an image receiving unit 2306.

  FIG. 8E shows a rear projector, and light emitted from a light source 2402 disposed inside a main body 2401 is reflected and modulated by a pixel portion of a reflective liquid crystal display device 2403. The reflected light passes through the polarizing beam splitter 2504 and the reflectors 2505 and 2506 and is projected on the screen 2507 and displayed as an image.

  In the electronic devices shown in FIGS. 8A to 8E, the reflective liquid crystal display devices 2005, 2102, 2202, 2302, and 2403 are provided with the pixel portion of the present invention, and for controlling the pixel portion. The peripheral drive circuit is also formed on the same substrate as the pixel portion. The liquid crystal material is appropriately selected according to the display mode, such as a ferroelectric liquid crystal or an anti-ferroelectric liquid crystal.

  With the structure of the pixel portion of the present invention, light degradation of the active element is prevented, so that the lifetime can be extended and the reliability can be improved. In particular, the present invention is very effective for an electronic apparatus that emits strong light such as the rear projector in FIG.

  In addition, since there is no reflected light other than the pixel electrodes, high-contrast and high-quality display can be realized. This effect is very effective for an electronic apparatus that projects an enlarged image several tens to several hundreds of times like the rear projector of FIG.

  In addition, since the step of the pixel electrode is flattened or relaxed by the light absorber, there is no disturbance in the alignment of the liquid crystal molecules at the step, and the contrast caused by this disturbance in alignment, particularly the black display, is reduced. Can be eliminated.

  The effect of preventing disorder of the alignment of liquid crystal molecules is particularly effective for a reflective liquid crystal display device having a cell gap of about 2 to 4 μm, and a ferroelectric liquid crystal / antiferroelectric liquid crystal display device having a cell gap of 2 μm or less. . Further, since the projector shown in FIG. 8E has a large number of pixels and a small area, preventing the disturbance of orientation is very effective for improving the image quality. Another structure of the projector is shown in FIG.

  FIG. 8F illustrates a front projector. In a main body 2501, light from a light source 2502 is modulated by a transmissive liquid crystal display device 2503 and transmitted. This transmitted light is projected onto the screen 2505 by the optical system 2504, and an image is displayed. The pixel portion of the present invention is used for the transmissive display device 2503, and high-definition display can be realized.

  In the first to fourth embodiments, the liquid crystal display device has been described. However, the pixel portion of the present invention can be applied to other active matrix display devices such as an EL display device, and light deterioration of the active elements in the pixel portion is caused by a light absorber. Can be prevented.

2 is a front view and a cross-sectional view of a pixel portion according to Embodiment 1. FIGS. 4A and 4B are a front view and a cross-sectional view for explaining a manufacturing process of a pixel portion of Embodiment 1. FIGS. FIGS. 4A and 4B are a front view and a cross-sectional view for explaining a manufacturing process of a pixel portion of Embodiment 1. FIGS. FIGS. 4A and 4B are a front view and a cross-sectional view for explaining a manufacturing process of a pixel portion of Embodiment 1. FIGS. 9 is a cross-sectional view illustrating a manufacturing process of a pixel portion in Example 1. FIG. The enlarged view of the groove part for demonstrating the preparation process of the light absorber of Example 1. FIG. Sectional drawing for demonstrating the manufacturing process of the pixel part of Example 3. FIG. Explanatory drawing of the application product of the electronic device of Example 4. FIG. The front view and sectional drawing of the pixel part of a prior art example.

Explanation of symbols

100 Substrate 101 Active layer 102 Gate insulating film 104 Gate electrode 105 Gate wiring 107 Source region 108 Drain region 109 Channel formation region 110 First interlayer insulating film 111 Source electrode 112 Source wiring 113 Drain electrode 114 Second interlayer insulating film 115 Pixel Electrode 116 Resist mask 120 Groove 121 Insulator layer 122 Light absorber 201 Insulator layer 202 Light absorber

Claims (8)

Forming a first interlayer insulating film covering the plurality of transistors;
Forming a wiring on the first interlayer insulating film;
Forming a second interlayer insulating film covering the wiring on the first interlayer insulating film, forming a conductive film on the second interlayer insulating film;
Forming a resist on the conductive film;
By etching the conductive film using the resist as a mask, a plurality of pixel electrodes are formed so that the gaps between adjacent pixel electrodes and the wirings overlap each other.
Etching the second interlayer insulating film using the resist as a mask to form a groove at a position overlapping the gap and the wiring,
An insulating light absorber is formed in the groove and on the resist mask surface,
Etching the light absorber and the resist to leave a part of the light absorber and the resist inside the groove,
A method of manufacturing an electronic device, wherein the light absorber is processed into a shape protruding from the surface of the pixel electrode by removing only the resist. In claim 1 ,
The method for manufacturing an electronic device, wherein the light absorbing material includes an oxidation coating film in which a pigment or a carbon-based material is dispersed. In claim 1 ,
The method for manufacturing an electronic device, wherein the light absorber is made of an organic resin in which a pigment or a carbon-based material is dispersed. In claim 3 ,
The method for manufacturing an electronic device, wherein the light absorber is made of acrylic in which a pigment or a carbon-based material is dispersed. In claim 3 ,
The method for manufacturing an electronic device, wherein the light absorber is made of polyimide in which a pigment or a carbon-based material is dispersed. In claim 3 ,
The method for manufacturing an electronic device, wherein the light absorber is made of a polyamide in which a pigment or a carbon-based material is dispersed. In claim 3 ,
The method for manufacturing an electronic device, wherein the light absorber is made of polyimide amide in which a pigment or a carbon-based material is dispersed. In claim 3 ,
The method for manufacturing an electronic device, wherein the light absorber is made of epoxy in which a pigment or a carbon-based material is dispersed.

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