JP2009295725A - Method for manufacturing of substrate for electrooptical device, substrate for electrooptical device, electrooptical device, and electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suit to microfabrication of a semiconductor layer for structuring a TFT, and to reduce generation of optical leak current in the TFT. <P>SOLUTION: The method for manufacturing of a substrate for an electrooptical device includes a process for forming a semiconductor film (1ap) on a substrate (10), a process for forming an oxidation preventing film (700) for preventing oxidation of the semiconductor film on the semiconductor film, a process for forming a semiconductor layer (1a) by patterning the oxidation preventing film and semiconductor film collectively by a photolithography method and an etching method, a process for oxidizing at least a part of a side surface of the semiconductor layer by carrying out oxidation treatment in a state that the oxidation preventing film is formed on the semiconductor layer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing an electro-optical device substrate used in an electro-optical device such as a liquid crystal device, an electro-optical device substrate, an electro-optical device, and an electronic device such as a liquid crystal projector.

  A liquid crystal device which is an example of this type of electro-optical device is frequently used not only as a direct-view display but also as a light modulation means (light valve) of, for example, a projection display device. In particular, in the case of a projection display device, since a relatively strong light is incident from a light source, a light leakage current is generated in a thin film transistor (TFT) in the device, which may cause deterioration in image quality or malfunction. There is.

  For example, in Patent Document 1, a TFT having an LDD (Lightly Doped Drain) structure is formed between a source / drain region connected to a pixel electrode and a channel region among LDD regions formed on both sides of the channel region. By making the width of the pixel electrode side LDD region smaller than the width of the data line side LDD region formed between the source / drain region connected to the data line and the channel region, the light is incident on the pixel electrode side LDD region. A technique for reducing the amount of light is disclosed.

Japanese Patent Laid-Open No. 2004-340981

  However, in the manufacturing process, when the semiconductor layer constituting the TFT is to be miniaturized only by the photolithography method and the etching method, the semiconductor layer is smaller than the limit width corresponding to the capability (or performance) of the exposure apparatus. There is a technical problem that it is difficult to miniaturize to have a width. For this reason, for example, the width of the pixel electrode side LDD region cannot be made smaller than the limit width according to the capability of the exposure apparatus, so that the light leakage current in the TFT cannot be sufficiently reduced, and the image quality is improved. There is a technical problem that it is difficult to improve.

  The present invention has been made in view of, for example, the above-described problems. For example, the present invention is suitable for miniaturization of a semiconductor layer constituting a TFT, and is an electro-optical device substrate that can reduce generation of light leakage current in the TFT. It is an object to provide a manufacturing method, an electro-optical device substrate, an electro-optical device including the electro-optical device substrate, and an electronic apparatus including the electro-optical device.

  In order to solve the above problems, an electro-optical device manufacturing method according to the present invention includes a pixel electrode and a transistor including a semiconductor layer electrically connected to the pixel electrode on the substrate. An electro-optical device substrate manufacturing method for manufacturing a device substrate, comprising: forming a semiconductor film on the substrate; and forming an antioxidant film on the semiconductor film to prevent oxidation of the semiconductor film Forming the semiconductor layer by patterning the antioxidant film and the semiconductor film in a lump by a photolithography method and an etching method, and forming the antioxidant film on the semiconductor layer. In this state, the pixel electrode is shaped so as to be electrically connected to the semiconductor layer by oxidizing the at least part of the side surface of the semiconductor layer by performing an oxidation treatment. And a step of.

  According to the method for manufacturing a substrate for an electro-optical device according to the present invention, a semiconductor film such as a polysilicon film is first formed on a substrate such as a glass substrate. At this time, the semiconductor film is typically formed on the entire surface of the substrate.

  Next, an antioxidant film for preventing oxidation of the semiconductor film is formed on the semiconductor film. The antioxidant film is formed of, for example, a nitride film such as a silicon nitride film (SiN film) or a titanium nitride film (TiN film).

  Next, the antioxidant film and the semiconductor film are collectively patterned by a photolithography method and an etching method, thereby forming a semiconductor layer. At this time, the semiconductor layer is typically formed in a predetermined plane pattern including a portion having a minimum limit width in patterning by a photolithography method and an etching method. Here, the minimum limit width means a minimum width that can be patterned by a photolithography method and an etching method, and depends on, for example, the capability of an exposure apparatus or the like.

  Next, in a state where the antioxidant film is formed on the semiconductor layer, for example, an oxidation treatment such as a thermal oxidation treatment using a heating furnace is performed to oxidize at least a part of the side surface of the semiconductor layer. Here, in particular, since the antioxidant film is formed on the semiconductor layer (in other words, the upper surface of the semiconductor layer), the upper surface side of the semiconductor layer is not oxidized by the oxidation treatment. In other words, the oxidation treatment is performed in a state in which the upper surface of the semiconductor layer is covered with an antioxidant film and at least a part of the side surface of the semiconductor layer is exposed to an oxygen atmosphere (that is, a state in which at least a part of the side surface of the semiconductor layer is exposed). As a result, at least a part of the side surface of the semiconductor layer is oxidized while preventing oxidation of the upper surface of the semiconductor layer.

  Thus, by oxidizing at least a part of the side surface of the semiconductor layer, the width of at least a part of the semiconductor layer can be reduced. That is, by oxidizing at least a part of a side surface of a semiconductor layer made of, for example, polysilicon, the side surface part of at least a part of the semiconductor layer can be changed to an oxide such as silicon oxide. Some widths can be reduced. Note that it is possible to adjust the width of at least a part of the semiconductor layer by changing the processing conditions (for example, the processing time) for performing the oxidation treatment in a state where the antioxidant film is formed on the semiconductor layer. is there. In other words, according to the method for manufacturing a substrate for an electro-optical device according to the present invention, the semiconductor layer can be formed to have a width smaller than a minimum limit width in patterning by a photolithography method and an etching method, for example. That is, it is possible to make the semiconductor layer finer than the capability of, for example, an exposure apparatus.

  Therefore, the light incident on the semiconductor layer can be reduced during the operation of the electro-optical device including the electro-optical device substrate manufactured by the electro-optical device substrate manufacturing method according to the present invention. Accordingly, generation of light leakage current in a transistor including a semiconductor layer can be reduced.

  Here, if the oxidation treatment is performed on the semiconductor layer in a state where the antioxidant film is not formed on the semiconductor layer, the upper surface and side surfaces of the semiconductor layer are oxidized. For this reason, when the side surface of the semiconductor layer is oxidized, the width of the semiconductor layer is reduced and the layer thickness (or film thickness) of the semiconductor layer is also reduced. Therefore, the on-state current of the transistor including the semiconductor layer may be reduced.

  However, in the present invention, in particular, since the oxidation treatment is performed in a state where an antioxidant film made of, for example, a nitride film is formed on the semiconductor layer, at least one of the semiconductor layers can be prevented while reliably preventing oxidation of the upper surface of the semiconductor layer. The side of the part can be oxidized. Therefore, the thickness of the semiconductor layer can be prevented from being reduced, and at least a part of the width of the semiconductor layer can be reduced. Therefore, generation of light leakage current can be reduced while suppressing a decrease in on-state current of the transistor including the semiconductor layer.

  As described above, according to the method for manufacturing a substrate for an electro-optical device according to the present invention, the semiconductor layer constituting the transistor can be miniaturized beyond the capability of, for example, an exposure apparatus. Therefore, it is possible to reduce the occurrence of light leakage current in the transistor during the operation of the electro-optical device including the electro-optical device substrate manufactured by the method for manufacturing the electro-optical device substrate according to the present invention.

  According to the aspect of the method for manufacturing the substrate for an electro-optical device according to the invention, in the step of forming the antioxidant film, the antioxidant film is formed from a nitride film.

  According to this aspect, since the antioxidant film is formed of a nitride film such as a silicon nitride film or a titanium nitride film, oxidation of the upper surface of the semiconductor layer due to oxidation treatment can be suitably prevented.

  According to another aspect of the method for manufacturing a substrate for an electro-optical device according to the present invention, the method further includes a step of removing the antioxidant film formed on the semiconductor layer after the step of oxidizing the side surface.

  According to this aspect, after at least a part of the side surface of the semiconductor layer is oxidized, the antioxidant film is removed by, for example, a wet etching process using sulfuric acid, hot phosphoric acid, or the like. Therefore, the antioxidant film can be prevented from adversely affecting the characteristics of the transistor.

  In the aspect further including the step of removing the antioxidant film, the step of forming a gate oxide film in which the upper surface of the semiconductor layer is oxidized by performing an oxidation treatment after the step of removing the antioxidant film. May further be included.

  In this case, the gate electrode of the transistor and the channel region of the semiconductor layer can be suitably insulated by a gate oxide film made of, for example, a silicon oxide film formed by oxidizing the upper surface of the semiconductor layer made of, for example, polysilicon. it can.

  In order to solve the above problems, an electro-optical device substrate of the present invention has a pixel electrode, (i) a semiconductor layer electrically connected to the pixel electrode, and (ii) an upper surface of the semiconductor layer. And (iii) a transistor including a gate electrode provided on the semiconductor layer via the gate oxide film, and at least a part of a side surface of the semiconductor layer is oxidized. And a side-surface oxidized portion having a thickness from the side surface larger than the thickness of the gate oxide film.

  According to the substrate for an electro-optical device of the present invention, the semiconductor layer constituting the transistor can be miniaturized beyond the capability of, for example, an exposure apparatus, as in the above-described method for manufacturing a substrate for an electro-optical device according to the present invention. Is possible. Therefore, it is possible to reduce the occurrence of light leakage current in the transistor during the operation of the electro-optical device including the electro-optical device substrate according to the present invention.

  Here, in particular, the thickness of the side surface oxidized portion from the side surface of the semiconductor layer is larger than the thickness of the gate oxide film formed by oxidizing the upper surface of the semiconductor layer. That is, in the present invention, it is avoided that the depth at which the upper surface of the semiconductor layer is oxidized becomes the same as the depth at which the side surface of the semiconductor layer is oxidized, and the thickness of the semiconductor layer becomes too small. Can be prevented. Thus, a reduction in on-state current of the transistor can be suppressed.

  In order to solve the above problems, an electro-optical device of the present invention includes the above-described substrate for an electro-optical device of the present invention.

  According to the electro-optical device of the present invention, since the above-described electro-optical device substrate of the present invention is provided, generation of light leakage current in the transistor can be reduced. As a result, a high quality image can be displayed.

In order to solve the above problems, an electronic apparatus according to the present invention includes the above-described electro-optical device according to the present invention.
According to the electronic apparatus of the present invention, since it includes the electro-optical device of the present invention described above, a projection display device, a mobile phone, an electronic notebook, a word processor, and a viewfinder capable of performing high-quality display. Various electronic devices such as a video tape recorder, a workstation, a videophone, a POS terminal, and a touch panel can be realized. In addition, as an electronic apparatus according to the present invention, for example, an electrophoretic device such as electronic paper can be realized.

  The operation and other advantages of the present invention will become apparent from the best mode for carrying out the invention described below.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, a TFT active matrix driving type liquid crystal device with a built-in driving circuit, which is an example of the electro-optical device of the present invention, is taken as an example.
<First Embodiment>
The liquid crystal device according to this embodiment will be described with reference to FIGS.

  First, the overall configuration of the liquid crystal device according to the present embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a plan view showing the overall configuration of the liquid crystal device according to this embodiment, and FIG. 2 is a cross-sectional view taken along the line H-H ′ of FIG. 1.

  1 and 2, in the liquid crystal device according to the present embodiment, a TFT array substrate 10 and a counter substrate 20 are arranged to face each other. The TFT array substrate 10 is, for example, a transparent substrate such as a quartz substrate or a glass substrate, a silicon substrate, or the like. The counter substrate 20 is a transparent substrate such as a quartz substrate or a glass substrate. A liquid crystal layer 50 is sealed between the TFT array substrate 10 and the counter substrate 20. The TFT array substrate 10 and the counter substrate 20 are bonded to each other by a sealing material 52 provided in a sealing region located around the image display region 10a provided with a plurality of pixel electrodes.

  The sealing material 52 is made of, for example, an ultraviolet curable resin, a thermosetting resin, or the like for bonding the two substrates, and is applied on the TFT array substrate 10 in the manufacturing process and then cured by ultraviolet irradiation, heating, or the like. It is. In the sealing material 52, a gap material such as glass fiber or glass bead is dispersed for setting the distance between the TFT array substrate 10 and the counter substrate 20 (that is, the inter-substrate gap) to a predetermined value.

  A light-shielding frame light-shielding film 53 that defines the frame area of the image display area 10a is provided on the counter substrate 20 side in parallel with the inside of the seal area where the sealing material 52 is disposed. However, part or all of the frame light shielding film 53 may be provided as a built-in light shielding film on the TFT array substrate 10 side.

  A data line driving circuit 101 and an external circuit connection terminal 102 are provided along one side of the TFT array substrate 10 in a region located outside the sealing region in which the sealing material 52 is disposed in the peripheral region. The sampling circuit 7 is provided so as to be covered with the frame light shielding film 53 on the inner side of the seal region along the one side. The scanning line driving circuit 104 is provided along two sides adjacent to the one side so as to be covered with the frame light shielding film 53.

  On the TFT array substrate 10, vertical conduction terminals 106 for connecting the two substrates with the vertical conduction material 107 are arranged in regions facing the four corner portions of the counter substrate 20. Thus, electrical conduction can be established between the TFT array substrate 10 and the counter substrate 20.

  In FIG. 2, on the TFT array substrate 10, a laminated structure is formed in which wirings such as TFTs for pixel switching, scanning lines, and data lines are formed. In the image display area 10a, pixel electrodes 9a made of a transparent material such as ITO (Indium Tin Oxide) are provided in a matrix on the upper layer of wiring such as pixel switching TFTs, scanning lines, and data lines. An alignment film is formed on the pixel electrode 9a. On the other hand, a light shielding film 23 is formed on the surface of the counter substrate 20 facing the TFT array substrate 10. The light shielding film 23 is formed of, for example, a light shielding metal film or the like, and is patterned in, for example, a lattice shape or a stripe shape in the image display region 10a on the counter substrate 20. On the light shielding film 23, a counter electrode 21 made of a transparent material such as ITO is formed over the entire surface of the counter substrate 20 (for example, in a solid shape) so as to face the plurality of pixel electrodes 9a. An alignment film is formed on the counter electrode 21.

  A liquid crystal layer 50 is formed between the TFT array substrate 10 and the counter substrate 20 that are configured as described above and are arranged so that the pixel electrode 9a and the counter electrode 21 face each other. The liquid crystal layer 50 is made of, for example, a liquid crystal in which one or several types of nematic liquid crystals are mixed, and takes a predetermined alignment state between the pair of alignment films.

  2, in the liquid crystal device according to the present embodiment, the portion on the lower layer side of the alignment film provided on the TFT array substrate 10 side is an example of the “substrate for the electro-optical device” according to the present invention. Constitutes a circuit board.

  1 and FIG. 2, on the TFT array substrate 10, in addition to the drive circuits such as the data line drive circuit 101 and the scanning line drive circuit 104, a plurality of data lines are precharged at a predetermined voltage level. There may be formed a precharge circuit for supplying a signal prior to an image signal, an inspection circuit for inspecting quality, defects, etc. of the electro-optical device during manufacturing or at the time of shipment, an inspection pattern, and the like.

  Next, the electrical configuration of the image display area of the liquid crystal device according to the present embodiment will be described with reference to FIG. FIG. 3 is an equivalent circuit diagram of various elements, wirings, and the like in a plurality of pixels formed in a matrix forming the image display area of the liquid crystal device according to this embodiment.

  In FIG. 3, a pixel electrode 9 a and a pixel switching TFT 30 as an example of the “transistor” according to the present invention are formed in each of a plurality of pixels formed in a matrix form constituting the image display region 10 a. . The TFT 30 is electrically connected to the pixel electrode 9a, and performs switching control of the pixel electrode 9a during the operation of the liquid crystal device according to the present embodiment. The data line 6a to which the image signal is supplied is electrically connected to the source of the TFT 30. The image signals S1, S2,..., Sn to be written to the data lines 6a may be supplied line-sequentially in this order, or may be supplied for each of a plurality of adjacent data lines 6a. Good.

  The scanning line 11a is electrically connected to the gate of the TFT 30, and the liquid crystal device according to this embodiment applies the scanning signals G1, G2,..., Gm to the scanning line 11a in a pulsed manner at a predetermined timing. It is configured to apply in a line sequential order. The pixel electrode 9a is electrically connected to the drain of the TFT 30, and the image signal S1, S2,..., Sn supplied from the data line 6a is obtained by closing the TFT 30 as a switching element for a certain period. It is written at a predetermined timing. Image signals S1, S2,..., Sn written to the liquid crystal via the pixel electrode 9a are constant between the counter electrode 21 (see FIG. 2) formed on the counter substrate 20 (see FIG. 2). Hold for a period.

  The liquid crystal constituting the liquid crystal layer 50 (see FIG. 2) modulates light and enables gradation display by changing the orientation and order of the molecular assembly depending on the applied voltage level. In the normally white mode, the transmittance for incident light is reduced according to the voltage applied in units of each pixel, and in the normally black mode, the light is incident according to the voltage applied in units of each pixel. The transmittance for light is increased, and light having a contrast corresponding to an image signal is emitted from the liquid crystal device as a whole.

  In order to prevent the image signal held here from leaking, a storage capacitor 70 is added electrically in parallel with the liquid crystal capacitor formed between the pixel electrode 9a and the counter electrode 21 (see FIG. 2). ing. One electrode of the storage capacitor 70 is electrically connected to the drain of the TFT 30 in parallel with the pixel electrode 9a, and the other electrode is electrically connected to the fixed potential capacitor line 300 so as to have a constant potential. It is connected to the.

  Next, a specific configuration of the pixel switching TFT according to this embodiment will be described with reference to FIGS. FIG. 4 is a plan view showing the configuration of the pixel switching TFT, and FIG. 5 is a cross-sectional view taken along the line A-A ′ of FIG. 4. In FIG. 5, the scales of the layers and members are different from each other in order to make the layers and members recognizable on the drawing.

  4 and 5, the pixel switching TFT 30 is formed on the entire surface of the TFT array substrate 10 for each pixel on the base insulating film 12 formed of, for example, a silicon oxide film. The underlying insulating film 12 is formed on the entire surface of the TFT array substrate 10, thereby preventing a change in characteristics of the pixel switching TFT 30 due to roughness during polishing of the surface of the TFT array substrate 10 or dirt remaining after cleaning. Have. A scanning line 11a made of, for example, tungsten (W), titanium (Ti), titanium nitride (TiN), or the like is formed on the TFT array substrate 10 below the base insulating film 12. The scanning line 11a is made of a light-shielding material, so that return light such as light reflected from the back surface of the TFT array substrate 10 or light emitted from another liquid crystal device by a multi-plate projector or the like and penetrating the composite optical system is used. Of these, it also functions as a lower light-shielding film that shields light traveling to the TFT 30.

  The TFT 30 includes a semiconductor layer 1a, a gate oxide film 2, and a gate electrode 3a.

  The semiconductor layer 1a includes polysilicon and includes a channel region 1a ′, a data line side LDD region 1b and a pixel electrode side LDD region 1c, a data line side source / drain region 1d, and a pixel electrode side source / drain region 1e. . That is, the TFT 30 has an LDD structure.

  As shown in FIG. 4, the data line side source / drain region 1d and the pixel electrode side source / drain region 1e are formed substantially in mirror symmetry along the Y direction with respect to the channel region 1a '. The data line side LDD region 1b is formed between the channel region 1a 'and the data line side source / drain region 1d. The pixel electrode side LDD region 1c is formed between the channel region 1a 'and the pixel electrode side source / drain region 1e. The data line side LDD region 1b, the pixel electrode side LDD region 1c, the data line side source / drain region 1d, and the pixel electrode side source / drain region 1e are formed by implanting impurities into the semiconductor layer 1a by, for example, ion implantation. This is an impurity region. The data line side LDD region 1b and the pixel electrode side LDD region 1c are formed as low concentration impurity regions with less impurities than the data line side source / drain region 1d and the pixel electrode side source / drain region 1e, respectively. According to such an impurity region, when the TFT 30 is not operating, the off-current flowing between the data line side source / drain region 1d and the pixel electrode side source / drain region 1e is reduced, and the on-current flowing when the TFT 30 is operating is reduced. Can be suppressed.

  4 and 5, the data line side source / drain region 1 d is electrically connected to the data line 6 a formed on the interlayer insulating film 41 through a contact hole formed in the interlayer insulating film 41. Yes. Although not shown here, the pixel electrode side source / drain region 1e is electrically connected to the pixel electrode 9a formed on the uppermost layer side through a contact hole or a relay layer opened on the interlayer insulating film 41. It is connected to the.

  The TFT 30 may have an offset structure in which no impurity is implanted into the data line side LDD region 1b and the pixel electrode side LDD region 1c. Alternatively, the TFT 30 may be implanted with a high concentration of impurities using the gate electrode as a mask. A self-aligned type in which the region and the pixel electrode side source / drain region are formed may be used.

  The gate electrode 3a is made of, for example, conductive polysilicon having light shielding properties, and is disposed to face the channel region 1a 'in the semiconductor layer 1a with the gate oxide film 2 interposed therebetween. The gate electrode 3a has a main body portion facing the channel region 1a ′, and an extending portion extending from the main body portion to the side of the semiconductor layer 1a. The extending portion opens to the base insulating film 12. It is electrically connected to the scanning line 11a through the perforated contact hole.

  The gate oxide film 2 is made of a silicon oxide film formed by oxidizing the upper surface of the semiconductor layer 1a.

  4 and 5, in the present embodiment, a side surface oxidation portion 60 is formed on the side surface of the semiconductor layer 1a.

  As will be described later in detail, the side surface oxidation portion 60 is formed by oxidizing the side surface of the semiconductor layer 1a in the manufacturing process, and is made of silicon oxide. By forming the side oxidation portion 60, the width W1 of the semiconductor layer 1a is made finer than the capability of, for example, an exposure apparatus. Therefore, during operation of the liquid crystal device according to the present embodiment, light incident on the semiconductor layer 1a (particularly, light incident on the pixel electrode side LDD region 1c, which is a region where light leakage current is likely to occur in the semiconductor layer 1a). Can be reduced. Therefore, generation of light leakage current in the TFT 30 can be reduced.

  Further, particularly in the present embodiment, the thickness d1 of the side surface oxidation portion 60 from the side surface of the semiconductor layer 1a is larger than the film thickness d2 of the gate oxide film 2 formed by oxidizing the upper surface of the semiconductor layer 1a. That is, in the present embodiment, the depth at which the upper surface of the semiconductor layer 1a is oxidized is prevented from being the same as the depth at which the side surface of the semiconductor layer 1a is oxidized. Therefore, it is possible to prevent the layer thickness T1 of the semiconductor layer 1a from becoming too small. Therefore, a decrease in on-current of the TFT 30 can be suppressed.

  Next, a manufacturing method for manufacturing a liquid crystal device substrate included in the above-described liquid crystal device will be described with reference to FIGS. 6 and 7 are process cross-sectional views sequentially showing the manufacturing process of the liquid crystal device substrate according to this embodiment. 6 and 7 are shown corresponding to the cross-sectional view shown in FIG. In the following, for the convenience of explanation, a process for forming a pixel switching TFT that achieves the effect of the present embodiment will be mainly described, and a process for forming other components will be described. The description of is omitted as appropriate.

  First, in the step shown in FIG. 6A, an image display region 10a (see FIG. 1) on the TFT array substrate 10 is made of a high melting point metal such as W, Ti, TiN, Cr, Ta, or Mo. The scanning lines 11a having a predetermined pattern are formed by laminating at least one simple metal, alloy, metal silicide, polysilicide, or a laminate thereof. At this time, the scanning line 11a is formed in a substantially striped pattern as a predetermined pattern so as to have a portion overlapping with the TFT 30 to be formed later.

  Subsequently, a base insulating film 12 is formed on the entire surface of the TFT array substrate 10. The base insulating film 12 may be formed by, for example, TEOS (tetraethyl orthosilicate) gas, TEB (tetraethyl boatrate) gas, TMOP (tetramethylmethylrate) by atmospheric pressure or low pressure CVD (Chemical Vapor Deposition) method. It is formed from a silicate glass film such as NSG, PSG, or BSG, a nitride film, a silicon oxide film, or the like using an oxy-phosphorate gas or the like. Note that after the base insulating film 12 is formed, the surface thereof may be flattened by performing a flattening process such as a CMP (Chemical Mechanical Polishing) process.

  Subsequently, a semiconductor film 1ap which is a precursor film of the semiconductor layer 1a is formed on the entire surface of the TFT array substrate 10. The semiconductor film 1ap is formed by solid-phase growth of a polysilicon film by forming an amorphous silicon film by, for example, low pressure CVD and performing heat treatment. The semiconductor film 1ap may be formed directly from a polysilicon film by, for example, a low pressure CVD method.

  Subsequently, a nitride film 700 as an example of the “antioxidation film” according to the present invention is formed on the semiconductor film 1ap so as to cover the entire upper surface of the semiconductor film 1ap. The nitride film 700 is formed using a nitrogen compound such as SiN or TiN, for example, by using a low pressure CVD method or a plasma CVD method.

  6B, a resist film 510 having a predetermined pattern corresponding to the planar pattern of the semiconductor layer 1a (see FIG. 4) is formed on the nitride film 700. At this time, the resist film 510 is formed so as to have a portion having a minimum limit width W2 corresponding to the capability of an exposure apparatus or the like, for example. For example, on the regions corresponding to the channel region 1a ′, the data line side LDD region 1b, the pixel electrode side LDD region 1c (see FIG. 4), the resist film 510 is formed with the minimum limit width W2.

  Subsequently, the nitride film 700 and the semiconductor film 1ap are etched using the resist film 510 as a mask, and the nitride film 700 and the semiconductor film 1ap are patterned at once. As a result, the semiconductor film 1ap is patterned to form the semiconductor layer 1a, and the patterned nitride film 700 remains on the semiconductor layer 1a. At this time, the semiconductor layer 1a includes a portion having the minimum limit width W2.

  Next, in the step shown in FIG. 7A, the side surface oxidized portion 60 made of silicon oxide is formed by oxidizing the side surface of the semiconductor layer 1a by performing an oxidation process such as a thermal oxidation process using a heating furnace, for example. To do. Here, particularly in the present embodiment, since the nitride film 700 is formed on the semiconductor layer 1a (in other words, the upper surface of the semiconductor layer 1a), the upper surface side of the semiconductor layer 1a is not oxidized by the oxidation treatment. . In other words, the upper surface of the semiconductor layer 1a is covered with the nitride film 700, and oxidation is performed in a state where the side surface of the semiconductor layer 1a is exposed to an oxygen atmosphere, thereby preventing oxidation of the upper surface of the semiconductor layer 1a. The side surface oxidized portion 60 is formed by oxidizing the side surface of the semiconductor layer 1a. Thereby, the semiconductor layer 1a can be formed to have a width W1 smaller than the minimum limit width W2. That is, the width of the semiconductor layer 1a can be reduced by changing the side surface portion of the semiconductor layer 1a to the side surface oxidized portion 60 by the oxidation treatment. In other words, the width of the semiconductor layer 1a is patterned by the etching process by forming the side surface oxidation part 60 by diffusing silicon oxide from the side surface side toward the inside in the semiconductor layer 1a made of polysilicon by the oxidation process. It can be smaller than the time point. That is, it is possible to make the semiconductor layer 1a finer than the capability of, for example, an exposure apparatus.

  Next, in the step shown in FIG. 7B, the nitride film 700 is removed by wet etching using, for example, sulfuric acid, hot phosphoric acid or the like. In this wet etching process, the nitride film 700 containing a nitrogen compound is removed, and the semiconductor layer 1a and the side-surface oxidized portion 60 described above are not affected and are not removed. Therefore, only the nitride film 700 can be preferably removed.

  Next, in the step shown in FIG. 7C, a predetermined region in the semiconductor layer 1a is doped with impurity ions at a predetermined concentration, whereby the channel region 1a ′, the data line side LDD region 1b, and the pixel electrode side. An LDD region 1c, a data line side source / drain region 1d, and a pixel electrode side source / drain region 1e are formed.

  Subsequently, a gate oxide film 2 made of silicon oxide is formed so as to cover the upper surface of the semiconductor layer 1a by performing an oxidation process such as a thermal oxidation process using a heating furnace, for example. At this time, the gate oxide film 2 is formed so that the film thickness d2 is smaller than the thickness d1 of the side surface oxidized portion 60 from the side surface of the semiconductor layer 1a. Therefore, it is possible to prevent the layer thickness T1 of the semiconductor layer 1a from becoming too small by forming the gate oxide film 2 by oxidizing the upper surface of the semiconductor layer 1a. Thereby, a decrease in the on-current of the TFT 30 can also be suppressed.

  Subsequently, the gate electrode 3a is formed in a predetermined plane pattern having a portion overlapping with the channel region 1a '. The gate electrode 3a is formed by depositing a polysilicon film by, for example, a low pressure CVD method and then thermally diffusing phosphorus (P) to make the polysilicon film conductive. Thus, the TFT 30 is constructed by forming the gate electrode 3a so as to face the channel region 1a 'with the gate oxide film 2 interposed therebetween. The gate electrode 3a is formed to have a main body corresponding to the channel region 1a ′ and an extending part extending from the main body part to the side of the semiconductor layer 1a. It is electrically connected to the scanning line 11a through the opened contact hole.

As described above, according to the manufacturing method according to the present embodiment, the semiconductor layer 1a constituting the pixel switching TFT 30 can be miniaturized beyond the capability of, for example, an exposure apparatus. Therefore, the light incident on the semiconductor layer 1a can be reduced during the operation of the liquid crystal device including the liquid crystal device substrate manufactured by the manufacturing method according to the present embodiment. Therefore, generation of light leakage current in the pixel switching TFT 30 can be reduced.
<Electronic equipment>
Next, the case where the liquid crystal device which is the above-described electro-optical device is applied to various electronic devices will be described. FIG. 8 is a plan view showing a configuration example of the projector. Hereinafter, a projector using the liquid crystal device as a light valve will be described.

  As shown in FIG. 8, a projector 1100 includes a lamp unit 1102 made of a white light source such as a halogen lamp. The projection light emitted from the lamp unit 1102 is separated into three primary colors of RGB by four mirrors 1106 and two dichroic mirrors 1108 arranged in the light guide 1104, and serves as a light valve corresponding to each primary color. The light enters the liquid crystal panels 1110R, 1110B, and 1110G.

  The configurations of the liquid crystal panels 1110R, 1110B, and 1110G are the same as those of the liquid crystal device described above, and are driven by R, G, and B primary color signals supplied from the image signal processing circuit. The light modulated by these liquid crystal panels enters the dichroic prism 1112 from three directions. In the dichroic prism 1112, R and B light is refracted at 90 degrees, while G light travels straight. Therefore, as a result of the synthesis of the images of the respective colors, a color image is projected onto the screen or the like via the projection lens 1114.

  Here, paying attention to the display images by the liquid crystal panels 1110R, 1110B, and 1110G, the display image by the liquid crystal panel 1110G needs to be horizontally reversed with respect to the display images by the liquid crystal panels 1110R and 1110B.

  In addition, since light corresponding to each primary color of R, G, and B is incident on the liquid crystal panels 1110R, 1110B, and 1110G by the dichroic mirror 1108, it is not necessary to provide a color filter.

  In addition to the electronic device described with reference to FIG. 8, a mobile personal computer, a mobile phone, a liquid crystal television, a viewfinder type, a monitor direct-view type video tape recorder, a car navigation device, a pager, an electronic device Examples include a notebook, a calculator, a word processor, a workstation, a videophone, a POS terminal, and a device equipped with a touch panel. Needless to say, the present invention can be applied to these various electronic devices.

  In addition to the liquid crystal devices described in the above embodiments, the present invention includes a reflective liquid crystal device (LCOS), a plasma display (PDP), a field emission display (FED, SED), an organic EL display, and a digital micromirror device. (DMD), electrophoresis apparatus and the like are also applicable.

  The present invention is not limited to the above-described embodiments, and can be appropriately changed without departing from the spirit or idea of the invention that can be read from the claims and the entire specification, and an electro-optical device with such a change. A substrate manufacturing method, an electro-optical device substrate, an electro-optical device, and an electronic apparatus are also included in the technical scope of the present invention.

It is a top view which shows the whole structure of the liquid crystal device which concerns on 1st Embodiment. It is the H-H 'sectional view taken on the line of FIG. FIG. 2 is an equivalent circuit diagram of various elements, wirings, and the like in a plurality of pixels formed in a matrix that forms an image display region of the liquid crystal device according to the first embodiment. It is a top view which shows the structure of TFT for pixel switching which concerns on 1st Embodiment. FIG. 5 is a cross-sectional view taken along line A-A ′ of FIG. 4. It is process sectional drawing (the 1) which shows the manufacturing process of the board | substrate for liquid crystal devices which concerns on 1st Embodiment later on. It is process sectional drawing (the 2) which shows the manufacturing process of the board | substrate for liquid crystal devices which concerns on 1st Embodiment later on. It is a top view which shows the structure of the projector which is an example of the electronic device to which the electro-optical apparatus is applied.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1ap ... Semiconductor film, 2 ... Gate oxide film, 3a ... Gate electrode, 6a ... Data line, 9a ... Pixel electrode, 10 ... TFT array substrate, 10a ... Image display area, 11a ... Scanning line, 12 ... Base insulating film, 20 ... counter substrate, 21 ... counter electrode, 30 ... TFT, 50 ... liquid crystal layer, 60 ... side oxidation part, 510 ... resist film, 700 ... nitride film

Claims (7)

An electro-optical device substrate manufacturing method for manufacturing an electro-optical device substrate including a pixel electrode and a transistor including a semiconductor layer electrically connected to the pixel electrode on the substrate,
Forming a semiconductor film on the substrate;
Forming an antioxidant film for preventing oxidation of the semiconductor film on the semiconductor film;
Forming the semiconductor layer by patterning the antioxidant film and the semiconductor film at once by a photolithography method and an etching method;
A step of oxidizing at least a part of the side surface of the semiconductor layer by performing an oxidation treatment in a state where the antioxidant film is formed on the semiconductor layer;
Forming the pixel electrode so as to be electrically connected to the semiconductor layer. A method for manufacturing a substrate for an electro-optical device.   2. The method of manufacturing a substrate for an electro-optical device according to claim 1, wherein in the step of forming the antioxidant film, the antioxidant film is formed from a nitride film.   The method for manufacturing a substrate for an electro-optical device according to claim 1, further comprising a step of removing the antioxidant film formed on the semiconductor layer after the step of oxidizing the side surface. .   4. The electricity according to claim 3, further comprising a step of forming a gate oxide film in which an upper surface of the semiconductor layer is oxidized by performing an oxidation process after the step of removing the antioxidant film. 5. A method for manufacturing a substrate for an optical device. On the board
A pixel electrode;
(I) a semiconductor layer electrically connected to the pixel electrode; (ii) a gate oxide film formed by oxidizing the upper surface of the semiconductor layer; and (iii) a gate oxide film on the semiconductor layer via the gate oxide film. A transistor including a provided gate electrode;
A substrate for an electro-optical device, comprising: a side surface oxidation portion in which at least a part of a side surface of the semiconductor layer is oxidized, and a thickness from the side surface is larger than a thickness of the gate oxide film.   An electro-optical device comprising the electro-optical device substrate according to claim 5.   An electronic apparatus comprising the electro-optical device according to claim 6.

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