JP2008288496A - Liquid crystal display unit and manufacturing method thereof, video display unit and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display unit that suppresses a leakage current and can reduce a size. <P>SOLUTION: On a quartz substrate 20, a thin-film transistor element having a channel region 6, a source region 7, a data line-side LDD region 8, a drain region 9 and a pixel electrode-side LDD region 10 is formed via a Wsi layer 21 and an SiO<SB>2</SB>layer 22, wherein a part of the data line-side LDD region and the pixel electrode-side LDD region is formed on the side surface of a convex part 11 formed of the SiO<SB>2</SB>layer. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device and a manufacturing method thereof, and an image display device and a manufacturing method thereof. Specifically, the present invention relates to a liquid crystal display device in which an LDD (Lightly Doped Drain) region is formed and a manufacturing method thereof, and a video display device using the liquid crystal display device in which an LDD region is formed and a manufacturing method thereof.

  Conventionally, a plurality of pixel driving elements are arranged corresponding to liquid crystal pixels, a plurality of data lines are connected to the pixel driving elements arranged in the vertical scanning direction, and the pixel driving elements are arranged in the horizontal scanning direction. A plurality of scan lines connected to each other, and sequentially supplying a vertical synchronizing signal to the scan lines and supplying a video signal to the data lines, thereby driving a pixel driving element to control a liquid crystal pixel. A circuit is known.

Hereinafter, a conventional liquid crystal driving circuit will be described with reference to the drawings.
FIG. 9 is a diagram for explaining a configuration of a liquid crystal driving circuit of a conventional active matrix liquid crystal display device. The liquid crystal driving circuit shown here includes a plurality of scan lines X ₁ arranged in parallel in the X-axis direction. , X ₂ , X ₃ ... And a plurality of data lines Y ₁ , Y ₂ , Y ₃ ... Arranged in parallel in the Y-axis direction, and at the intersection of each scan line and data line Is composed of a liquid crystal sandwiched between a pixel electrode corresponding to each active element and a counter electrode facing the active element T ₁₁ , T ₁₂ , T ₂₁ , T ₂₂ ... Such as a thin film transistor (TFT). Liquid crystal cells L ₁₁ , L ₁₂ , L ₂₁ , L ₂₂ ... Are formed. Each TFT is arranged in a matrix corresponding to the liquid crystal pixel, the gate electrode of each TFT is connected to the scan line, the source electrode is connected to the data line, and the drain electrode is the corresponding liquid crystal. It is connected to the pixel electrode of the cell.

Each data line is connected to a common video line 201 via a corresponding horizontal switch S ₁ , S ₂ , S ₃ ..., And a video signal is supplied from the video line. Further, the gate electrode of the switching transistor constituting each horizontal switch is connected to the horizontal scanning circuit 202. This horizontal scanning circuit boosts a signal input from the outside and sends a signal to the horizontal scanning circuit and the vertical scanning circuit. A horizontal switch drive pulse signal is sequentially applied to the gate electrode of the switching transistor in synchronization with the horizontal clock signal input from the level conversion circuit 203 to be output. Each scan line is connected to the vertical scanning circuit 204.

  In the circuit configured as described above, when the vertical scanning circuit is driven, the scan lines are excited line-sequentially, and a TFT is selected for each row. At this time, when the horizontal scanning circuit is driven and the switching transistors are operated in a line sequential manner, the video signal supplied to the video line is sequentially sampled on each data line. The sampled video signals are sequentially written into the corresponding liquid crystal cells via the TFTs selected for each row, and the sampling data of the video signals are written into the individual liquid crystal cells in a dot sequence.

  In recent years, higher brightness of liquid crystal display devices has been demanded, and in order to cope with higher brightness, the amount of light incident on the liquid crystal display device has increased. However, TFTs that switch pixels are silicon that is a semiconductor. When this TFT is exposed to light, optical carriers are generated, and a leak current flows even when the TFT is off. If this leakage current flows during the pixel potential holding period, the pixel potential deviates from an appropriate value and is visually recognized as pixel deterioration.

  In the liquid crystal driving circuit, when a DC voltage is applied to the liquid crystal, the specific resistance value of the liquid crystal is deteriorated. Even if pixels achieve the same transmittance, as shown in FIG. 10, there are two types: a high level (hereinafter referred to as “H level”) side and a low level (hereinafter referred to as “L level”) side. As shown in FIG. 11, the VGS (gate-source voltage) -IDS (drain-source current) characteristics of a TFT, which is a MOS transistor, are as follows. Differences in leakage current occur. That is, when the signal written on the H level side is held, VGS indicated by symbol A in FIG. 11 is applied, whereas when the signal written on the L level side is held, the symbol in FIG. Since VGS indicated by B is applied, the leakage current becomes larger when the signal written on the H level side is held than when the signal written on the L level side is held.

  Due to such characteristics, when attention is paid to an arbitrary row, as shown in FIG. 12, a large leak occurs in a period indicated by a symbol C in FIG. 12 that holds a signal written on the H level side with respect to Vcom. While the pixel potential greatly changes due to the current, the change in the pixel potential is small due to a small leak current in the period indicated by the symbol D in FIG. A change in potential occurs, and flicker that is flickering on the screen may be visually recognized by a change in pixel potential for each frame.

  In order to solve the problem due to the leakage current as described above, as shown in FIG. 13, the source connected to the channel region 206 and the data line in which the inversion layer is generated when a voltage higher than the threshold voltage is applied to the gate electrode 205. A data line side LDD region 208 of the high resistance layer is provided between the region 207 and a pixel electrode side LDD region 210 of the high resistance layer is provided between the channel region and the drain region 209 connected to the pixel electrode of the liquid crystal cell. Measures such as establishment are taken.

  Note that in a TFT in a conventional liquid crystal display device, a source region, an LDD region, a channel region, and a drain region are formed on the same plane (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 2001-209067

  Recently, however, liquid crystal display devices have been required to have higher brightness, and the amount of light incident on the liquid crystal display device has increased accordingly, and the same area as the source region, channel region, and drain region formation region has been developed. The method of forming the LDD region on the top cannot sufficiently solve the problem of leakage current.

  Further, in recent years, liquid crystal display devices have been miniaturized, and accordingly, thin film transistor elements have been required to be miniaturized. Note that when only miniaturization of the thin film transistor element is taken into consideration, as shown in FIG. 14, the length of the channel region (the distance indicated by the symbol a in FIG. 14) is reduced, or the length of the LDD region is increased. However, when the length of the channel region or the length of the LDD region is simply reduced, the source region and the drain region are close to each other. As a result, the leakage current increases.

  The present invention was devised in view of the above points, and is a liquid crystal display device capable of suppressing leakage current and miniaturizing, a manufacturing method thereof, and a video display device using such a liquid crystal display device and a manufacturing method thereof. It is intended to provide a method.

  In order to achieve the above object, a liquid crystal display device according to the present invention includes a pixel electrode arranged in a matrix, a first source or drain region connected to the pixel electrode, and a first electrode connected to a video signal. Two source or drain regions, the same conductivity type as the first source or drain region formed between the first source or drain region and the channel region, and more than the first source or drain region. The first high-resistance region having high resistance and the second source or drain region formed between the second source or drain region and the channel region and having the same conductivity type as the second source or drain A TFT substrate on which a thin film transistor element having a second high-resistance region having a higher resistance than the drain region is formed; and the TFT A liquid crystal display device comprising: a counter substrate disposed facing a plate with a predetermined gap; and a liquid crystal held in a gap between the TFT substrate and the counter substrate. At least a part of at least one of the two high resistance regions is formed on a side surface of a concave portion or a convex portion provided in the TFT substrate.

  Here, at least a part of at least one of the first high-resistance region and the second high-resistance region is formed on the side surface of the concave portion or the convex portion provided in the TFT substrate. Thus, miniaturization of the thin film transistor element can be realized without shortening the length of the first high resistance region or the second high resistance region. In addition, the first high-resistance region and the second high-resistance region that directly receive incident light are reduced, and a structure that is resistant to leakage current is realized.

  Since “at least a part of at least one region of the first high-resistance region or the second high-resistance region” is used, only one of the first high-resistance region or the second high-resistance region is included. It may be formed on the side surface of the concave portion or the convex portion, or both the first high resistance region or the second high resistance region may be formed on the side surface of the concave portion or the convex portion. Furthermore, only a part of the first high resistance region or the second high resistance region may be formed on the side surface of the concave portion or the convex portion, or the first high resistance region or the second high resistance region. The entire region may be formed on the side surface of the concave portion or the convex portion.

  In order to achieve the above object, a method of manufacturing a liquid crystal display device according to the present invention includes a pixel electrode arranged in a matrix, a first source or drain region connected to the pixel electrode, a video signal, A second source or drain region connected to the first source or drain region, the first source or drain region formed between the first source or drain region and the channel region, and having the same conductivity type as the first source Alternatively, the first high resistance region having a higher resistance than the drain region and the second source or drain region formed between the second source or drain region and the channel region and the same conductivity type, and the above TFT in which a thin film transistor element having a second high-resistance region having a higher resistance than the second source or drain region is formed In a method for manufacturing a liquid crystal display device, comprising: a plate; a counter substrate disposed facing the TFT substrate with a predetermined gap; and a liquid crystal held in the gap between the TFT substrate and the counter substrate. Forming a recess or a projection on the surface, and forming at least a part of at least one of the first high resistance region or the second high resistance region on a side surface of the recess or the projection, Is provided.

  Here, a concave portion or a convex portion is formed on the TFT substrate, and then at least a part of at least one region of the first high resistance region or the second high resistance region is formed on the side surface of the convex portion or the concave portion. Accordingly, miniaturization of the thin film transistor element is realized without shortening the length of the channel region, the first high resistance region, or the second high resistance region. In addition, the first high-resistance region and the second high-resistance region that directly receive incident light are reduced, and a structure that is resistant to leakage current is realized.

  In order to achieve the above object, a video display device according to the present invention is connected to pixel electrodes arranged in a matrix, a first source or drain region connected to the pixel electrodes, and a video signal. The second source or drain region, and the first source or drain region having the same conductivity type as the first source or drain region formed between the first source or drain region and the channel region. A first high resistance region having a higher resistance than the second source or drain region formed between the second source or drain region and the channel region, and the second conductivity or the second source or drain region. A TFT substrate on which a thin film transistor element having a second high resistance region having a higher resistance than the source or drain region is formed; A liquid crystal display device having a counter substrate disposed facing the FT substrate via a predetermined gap, and a liquid crystal held in the gap between the TFT substrate and the counter substrate, is modulated by the liquid crystal display device In the video display device that performs video display using light, at least a part of at least one of the first high-resistance region or the second high-resistance region is a recess provided in the TFT substrate or It is formed on the side surface of the convex portion.

  Here, at least a part of at least one of the first high-resistance region and the second high-resistance region is formed on the side surface of the concave portion or the convex portion provided in the TFT substrate. Thus, miniaturization of the thin film transistor element can be realized without shortening the length of the first high resistance region or the second high resistance region. In addition, the first high-resistance region and the second high-resistance region that directly receive incident light are reduced, and a structure that is resistant to leakage current is realized.

  In order to achieve the above object, a manufacturing method of a video display device according to the present invention includes a pixel electrode arranged in a matrix, a first source or drain region connected to the pixel electrode, a video signal, A second source or drain region connected to the first source or drain region, the first source or drain region formed between the first source or drain region and the channel region, and having the same conductivity type as the first source Alternatively, the first high resistance region having a higher resistance than the drain region and the second source or drain region formed between the second source or drain region and the channel region and the same conductivity type, and the above TFT in which a thin film transistor element having a second high-resistance region having a higher resistance than the second source or drain region is formed A liquid crystal display device comprising: a plate; a counter substrate disposed facing the TFT substrate via a predetermined gap; and a liquid crystal held in the gap between the TFT substrate and the counter substrate. And a step of forming a recess or a protrusion on the TFT substrate, and at least one of the first high-resistance region and the second high-resistance region. Forming at least a part of one of the regions on a side surface of the concave portion or the convex portion.

  Here, a concave portion or a convex portion is formed on the TFT substrate, and then at least a part of at least one region of the first high resistance region or the second high resistance region is formed on the side surface of the convex portion or the concave portion. Accordingly, miniaturization of the thin film transistor element is realized without shortening the length of the channel region, the first high resistance region, or the second high resistance region. In addition, the first high-resistance region and the second high-resistance region that directly receive incident light are reduced, and a structure that is resistant to leakage current is realized.

  In the liquid crystal display device to which the present invention is applied, the leakage current is suppressed and the size can be reduced. In addition, in the method for manufacturing a liquid crystal display device to which the present invention is applied, it is possible to obtain a liquid crystal display device that can suppress the leakage current and can be miniaturized.

  Similarly, the video display device to which the present invention is applied can suppress the leakage current and can be miniaturized. Further, in the method for manufacturing a video display device to which the present invention is applied, it is possible to obtain a video display device that can suppress the leakage current and can be miniaturized.

Hereinafter, embodiments of the present invention will be described with reference to the drawings to facilitate understanding of the present invention.
FIG. 1 is a diagram for explaining a configuration of a liquid crystal driving circuit of an active matrix type liquid crystal display device which is an example of a liquid crystal display device to which the present invention is applied. The liquid crystal driving circuit shown here is a conventional liquid crystal driving circuit. Similarly, a plurality of scan lines X ₁ , X ₂ , X ₃ ... Arranged in parallel to the X-axis direction and a plurality of data lines Y ₁ , Y ₂ , Y arranged in parallel to the Y-axis direction ₃ comprises a., the intersection of each scan line and the data line, for example, active device _T 11 such as a thin film transistor _{(TFT), T 12, T} 21, T 22 ··· are formed, and each Liquid crystal cells L ₁₁ , L ₁₂ , L ₂₁ , L ₂₂ ... Composed of liquid crystal sandwiched between a pixel electrode corresponding to an active element and a counter electrode facing each other are formed. Each TFT is arranged in a matrix corresponding to the liquid crystal pixel, the gate electrode of each TFT is connected to the scan line, the source electrode is connected to the data line, and the drain electrode is the corresponding liquid crystal. It is connected to the pixel electrode of the cell.

Each data line is connected to a common video line 1 through corresponding horizontal switches S ₁ , S ₂ , S ₃ ..., And a video signal is supplied from the video line. Further, the gate electrode of the switching transistor constituting each horizontal switch is connected to the horizontal scanning circuit 2, and this horizontal scanning circuit boosts the signal inputted from the outside and sends the signal to the horizontal scanning circuit and the vertical scanning circuit. A horizontal switch drive pulse signal is sequentially applied to the gate electrode of the switching transistor in synchronization with the horizontal clock signal input from the level conversion circuit 3 to be output. Each scan line is connected to the vertical scanning circuit 4.

  Further, a data line side LDD region 8 of a high resistance layer is provided between a channel region 6 where an inversion layer is generated when a voltage higher than the threshold voltage is applied to the gate electrode 5 and a source region 7 connected to the data line. The pixel electrode side LDD region 10 of the high resistance layer is provided between the channel region and the drain region 9 connected to the pixel electrode of the liquid crystal cell.

Further, in the liquid crystal display device to which the present invention is applied, the convex portion 11 made of the SiO ₂ layer is formed on the quartz substrate 20 on which the liquid crystal driving circuit is formed, and a part of the data line side LDD region and the side surface of the convex portion are formed. A part of the pixel electrode side LDD region is formed.

  Here, in this embodiment, a case where a convex portion is formed on a quartz substrate and a part of the data line side LDD region and a part of the pixel electrode side LDD region are formed on the side surface of the convex portion is taken as an example. Although described, the data line side LDD region and the pixel electrode side LDD region are the same in order to reduce the size of the thin film transistor element without reducing the length of the channel region, the data line side LDD region, or the pixel electrode side LDD region. It is sufficient if it is not formed on a plane. As shown in FIG. 2A, a recess is formed in the quartz substrate, and a part of the data line side LDD region and one of the pixel electrode side LDD region are formed on the side surface of the recess. A part may be formed.

  In this embodiment, the case where a part of the data line side LDD region and a part of the pixel electrode side LDD region are formed on the side surface of the convex part is described as an example. It is not necessary to form both the data line side LDD region and the pixel electrode side LDD region on the side surface, and only one of the data line side LDD region or the pixel electrode side LDD region may be formed on the side surface of the convex portion. Specifically, only a part of the data line side LDD region may be formed on the side surface of the convex portion (see FIG. 2B), or only a part of the pixel electrode side LDD region is formed on the side surface of the convex portion. May be formed (see FIG. 2C).

  It is to be noted that both the data line side LDD region and the pixel electrode side LDD region are formed on the side surface of the convex portion rather than only one of the data line side LDD region and the pixel electrode side LDD region. Therefore, it is preferable that both the data line side LDD region and the pixel electrode side LDD region are formed on the side surface of the convex portion.

  Further, in this embodiment, the case where a part of the data line side LDD region and a part of the pixel electrode side LDD region are formed on the side surface of the convex part is described as an example. It is not necessary to form only a part of the LDD region (data line side LDD region, pixel electrode side LDD region) on the side surface, and the LDD region (data line side LDD region, pixel electrode side LDD region) on the side surface of the convex portion. All may be formed (see FIG. 2D).

  Note that the entire LDD region (data line side LDD region, pixel electrode side LDD region) is formed rather than only a part of the LDD region (data line side LDD region, pixel electrode side LDD region) formed on the side surface of the convex portion. Is advantageous in terms of miniaturization of the thin film transistor element and reduction of a region directly exposed to incident light. Therefore, the entire LDD region (data line side LDD region, pixel electrode side LDD region) is formed. It is preferable to be formed on the side surface of the convex portion. However, when the entire LDD region (data line side LDD region, pixel electrode side LDD region) is formed on the side surface of the convex portion, only a part of the LDD region (data line side LDD region, pixel electrode side LDD region) is formed. Compared with the case where the protrusions are formed on the side surfaces of the protrusions, the height of the protrusions inevitably increases. Therefore, the LDD region (data line side LDD region, pixel electrode side) It is necessary to determine whether the entire LDD region is formed on the side surface of the convex portion or only a part of the LDD region (data line side LDD region, pixel electrode side LDD region) is formed on the side surface of the convex portion.

Further, in this embodiment, the case where the convex portion made of the SiO ₂ layer is formed on the quartz substrate has been described as an example. However, the convex portion is not necessarily formed by the SiO ₂ layer. As shown by 2 (e), a convex portion made of a polysilicon layer may be formed on a quartz substrate, and the convex portion made of the polysilicon layer may be covered with an SiO ₂ layer.

  Hereinafter, a method for manufacturing a liquid crystal driving circuit having the thin film transistor element shown in FIGS. 1 and 2E will be described. That is, an example of a method for manufacturing a liquid crystal display device to which the present invention is applied and another example will be described.

[1] Method for Manufacturing Liquid Crystal Drive Circuit Having Thin Film Transistor Element Shown in FIG. 1 In an example of a method for manufacturing a liquid crystal display device to which the present invention is applied, first, as shown in FIG. A WSi layer 21 having a thickness of 50 to 400 nm functioning as a film is formed, and subsequently, an SiO ₂ layer 22 having a thickness of about 800 nm functioning as an interlayer insulating film is formed on the WSi layer by a CVD method.

Next, the convex portion 11 having a height of about 400 nm is formed by processing the SiO ₂ layer using a general-purpose lithography technique and etching technique (see FIG. 3B). In this embodiment, the case where a convex portion having a height of about 400 nm is formed is described as an example, but the height of the convex portion is formed within the film thickness range of the formed SiO ₂ layer. Is possible.

  Subsequently, a channel polysilicon layer 23 to be a channel region of the thin film transistor element is formed by LPCVD (Low Pressure CVD) method or epitaxial growth method, and further, for the channel by solid phase growth method (Si implantation process and high temperature annealing process). The grain size of the polysilicon layer is adjusted according to the transistor characteristics (see FIG. 3C). In this embodiment, a polysilicon layer is formed as a channel region of the thin film transistor element. However, an amorphous silicon layer or a GaAs (gallium arsenide) Ge (germanium) layer may be used instead of the polysilicon layer.

  Next, a gate oxide film 24 of the thin film transistor element is formed (see FIG. 3D). Subsequently, impurities are implanted into the channel region of the thin film transistor element by an ion implantation method to set the threshold value (Vth) of the thin film transistor element. Adjust (refer to FIG. 3E).

Further, a PDAS (phosphorus-doped amorphous silicon) layer 25 having a thickness of 50 to 700 nm which functions as a gate electrode of the thin film transistor element is formed (see FIG. 4F). In this embodiment, a PDAS layer having a thickness of about 430 nm is formed by a CVD method. At this time, phosphorus is 3.0 × 10 ¹⁴ / cm ² so that the resistance value of the PDAS layer is about 4 KΩ / SQ. I included it.

  Next, an LDD region (data line side LDD region, pixel electrode side LDD region) is formed by implanting impurities into a predetermined region of the channel polysilicon layer (see FIG. 4G). Here, when ion-implanting impurities, a part of the impurity is implanted into the side surface of the convex portion, thereby forming a part of the data line side LDD region and a part of the pixel electrode side LDD region on the side surface of the convex portion. . In order to accurately form the LDD region (data line side LDD region, pixel electrode side LDD region) on the side surface of the convex portion, the LDD region (data Line side LDD region, pixel electrode side LDD region).

  Subsequently, a source region and a drain region of the thin film transistor are formed by implanting impurities into a predetermined region of the channel polysilicon layer (see FIG. 4H).

Further, a SiO ₂ layer 26 having a thickness of 200 to 1000 nm is formed by a CVD method, and contact holes 27 for making contact between the source region and the drain region of the thin film transistor element and the conductive film using general-purpose lithography technology and dry etching technology. Form. Subsequently, a conductive film 34 composed of three layers of WSi, AL, and WSi that carries the signal line potential is formed, and a predetermined wiring pattern is formed (see FIG. 4I). The conductive film may be any material such as Cr, Cu, Au, or Pt as long as it is a conductive metal film.

Subsequently, an SiO ₂ layer 28 functioning as an interlayer insulating film, a Ti layer 29 functioning as a surface light-shielding film, and an SiO ₂ layer 30 functioning as an interlayer insulating film are sequentially formed, and ITO (Indium-Tin Oxide) or the like is formed. By forming the transparent electrode 31 made of a transparent conductive material, a TFT substrate on which a liquid crystal driving circuit having the thin film transistor element shown in FIG. 1 is formed can be obtained (see FIG. 4J).

  Thereafter, the TFT substrate and the glass substrate are disposed facing each other with a predetermined gap therebetween, and liquid crystal is injected and sealed in the gap between the TFT substrate and the glass substrate, whereby a liquid crystal display device can be obtained.

[2] Manufacturing method of liquid crystal driving circuit having thin film transistor element shown in FIG. 2 (e) In another example of the manufacturing method of the liquid crystal display device to which the present invention is applied, first, as shown in FIG. A WSi layer 21 having a thickness of 50 to 400 nm functioning as a backside light shielding film is formed on the substrate 20, and then a SiO ₂ layer 22 having a thickness of about 400 nm functioning as an interlayer insulating film is formed on the upper layer of the WSi layer by a CVD method. To do.

Next, a polysilicon layer 32 having a thickness of about 400 nm is formed on the SiO ₂ layer by the LPCVD method or the epitaxial growth method, and then the polysilicon layer is processed by using a general-purpose lithography technique and etching technique. Protrusions 11 having a height of about 400 nm are formed (see FIG. 5B).

Subsequently, in order to prevent a short circuit between the polysilicon layer 31 and a channel polysilicon layer described later, a SiO ₂ layer 33 is formed on the polysilicon layer by a CVD method (see FIG. 5C). .

  Next, a channel polysilicon layer 23 serving as a channel region of the thin film transistor element is formed by LPCVD or epitaxial growth, and the grain size of the channel polysilicon layer is adjusted according to transistor characteristics by solid phase growth. (See FIG. 5D.) In this embodiment, a polysilicon layer is formed as a channel region of the thin film transistor element. However, an amorphous silicon layer or a GaAs (gallium arsenide) Ge (germanium) layer may be used instead of the polysilicon layer. Is the same as the manufacturing method of the liquid crystal driving circuit having the thin film transistor element shown in FIG.

  Next, a gate oxide film 24 of the thin film transistor element is formed, and then an impurity is implanted into the channel region of the thin film transistor element by ion implantation to adjust the threshold value (Vth) of the thin film transistor element (see FIG. 5E). .)

Further, a PDAS layer 25 having a thickness of 50 to 700 nm which functions as a gate electrode of the thin film transistor element is formed (see FIG. 6F). In this embodiment, a PDAS layer having a thickness of about 430 nm is formed by a CVD method. At this time, phosphorus is 3.0 × 10 ¹⁴ / cm ² so that the resistance value of the PDAS layer is about 4 KΩ / SQ. I included it.

  Next, an LDD region (data line side LDD region, pixel electrode side LDD region) is formed by ion-implanting impurities into a predetermined region of the channel polysilicon layer (see FIG. 6G). Here, when ion-implanting impurities, a part of the impurity is implanted into the side surface of the convex portion, thereby forming a part of the data line side LDD region and a part of the pixel electrode side LDD region on the side surface of the convex portion. . In order to accurately form the LDD region (data line side LDD region, pixel electrode side LDD region) on the side surface of the convex portion, the LDD region (data Line side LDD region, pixel electrode side LDD region).

  Subsequently, a source region and a drain region of the thin film transistor are formed by implanting impurities into a predetermined region of the channel polysilicon layer (see FIG. 6H).

Further, a SiO ₂ layer 26 having a thickness of 200 to 1000 nm is formed by a CVD method, and contact holes 27 for making contact between the source region and the drain region of the thin film transistor element and the conductive film using general-purpose lithography technology and dry etching technology. Form. Subsequently, a conductive film 34 composed of three layers of WSi, AL, and WSi that carries the signal line potential is formed, and a predetermined wiring pattern is formed (see FIG. 6I). The conductive film may be any material such as Cr, Cu, Au, or Pt as long as it is a conductive metal film.

Subsequently, an SiO ₂ layer 28 functioning as an interlayer insulating film, a Ti layer 29 functioning as a surface light-shielding film, and an SiO ₂ layer 30 functioning as an interlayer insulating film are sequentially formed, and ITO (Indium-Tin Oxide) or the like is formed. By forming the transparent electrode 31 made of a transparent conductive material, a TFT substrate on which a liquid crystal driving circuit having the thin film transistor element shown in FIG. 2E is formed can be obtained (see FIG. 6J).

  Thereafter, the TFT substrate and the glass substrate are disposed facing each other with a predetermined gap therebetween, and liquid crystal is injected and sealed in the gap between the TFT substrate and the glass substrate, whereby a liquid crystal display device can be obtained.

  In the liquid crystal display device to which the present invention is applied, since the data line side LDD region and the pixel electrode side LDD region are not formed on the same plane, specifically, the data line side LDD region is formed on the side surface of the convex portion. And a part of the pixel electrode side LDD region are formed, so that the thin film transistor element can be miniaturized without shortening the length of the channel region, the data line side LDD region, and the pixel electrode side LDD region. Can do.

Furthermore, since a part of the data line side LDD region and a part of the pixel electrode side LDD region are formed on the side surface of the convex portion, it is possible to reduce the region where the incident light directly hits the LDD region. A structure that is resistant to leakage current can be realized.
That is, when the data line side LDD region and the pixel electrode side LDD region are formed on the same plane (in the case of a thin film transistor element in a conventional liquid crystal display device), as shown in FIG. The incident light may directly hit all the regions of the side LDD region and the pixel electrode side LDD region (the region indicated by symbol c in FIG. 7), while the data line side LDD region 7 and part of the pixel electrode side LDD region (in the case of the thin film transistor element in the liquid crystal display device to which the present invention is applied), as shown in FIG. 7B, the data line side LDD Only the region that is not formed on the side surface of the convex portion in the region and the pixel electrode side LDD region (the region indicated by the symbol d in FIG. 7) is a region that may be directly exposed to incident light. As was, it is possible to reduce the area directly incident light strikes the LDD region, it is possible to realize a strong structure to leakage current.

  FIG. 8 is a schematic diagram for explaining a transmissive liquid crystal projector which is an example of an image display device to which the present invention is applied. The transmissive liquid crystal projector 100 shown here is a so-called three-plate system that uses red, green, and blue. This is a projection-type image display device that uses a liquid crystal display device to which the present invention is applied to three light valves corresponding to three primary colors and displays a color image enlarged and projected on a screen (not shown).

  Specifically, the transmissive liquid crystal projector includes a lamp 101 that is a light source that emits illumination light, an R dichroic mirror 103R that reflects only red light (R) among illumination light from the lamp, and illumination light from the lamp. Among them, a G dichroic mirror 103G that reflects only green light (G), and an R light valve 104R that is a light modulation means that modulates and transmits red light (R), green light (G), and blue light (B). , G light valve 104G and B light valve 104B, dichroic prism 105 which is a combining optical means for combining modulated red light (R), green light (G), and blue light (B), and combined illumination light And a projection lens 106 which is a projection means for projecting the image onto the screen.

  Here, the lamp emits white light including red light (R), green light (G), and blue light (B), and includes, for example, a halogen lamp, a metal halogen lamp, a xenon lamp, or the like.

  Further, in the optical path between the lamp and the R dichroic mirror, a filter 109 that cuts infrared rays and ultraviolet rays, a fly-eye lens 107 that equalizes the illuminance distribution of the illumination light emitted from the lamp, and the P of the illumination light , A polarization conversion element 108 for converting the S polarization component into one polarization component (for example, S polarization component) is disposed.

  Further, a total reflection mirror 110 that reflects red light (R) toward the R light valve is arranged between the R dichroic mirror and the R light valve, and between the G dichroic mirror and the B light valve, A total reflection mirror 110 that reflects blue light (B) toward the B light valve is disposed, and a relay lens 111 is disposed.

  The projection lens has a function of enlarging and projecting light from the dichroic prism toward the screen.

  In the transmissive liquid crystal projector configured as described above, white light emitted from the lamp is separated into red light (R), green light (G), and blue light (B) by the R dichroic mirror and the G dichroic mirror. . The separated red light (R), green light (G), and blue light (B) are incident on each light valve via the condenser lens 112. Red light (R), green light (G), and blue light (B) incident on each light valve are subjected to polarization modulation in accordance with a driving voltage applied to each pixel of each light valve, and then are dichroic prism. The synthesized light is enlarged and projected on the screen by the projection lens.

  As described above, in this transmissive liquid crystal projector, a color image is displayed by enlarging and projecting an image corresponding to the light modulated by the light valve on the screen.

  By the way, as described above, the liquid crystal display device that constitutes each light valve can suppress the leakage current and can be reduced in size. Therefore, the transmission current projector shown here can also suppress the leakage current. And can be miniaturized.

  In the present embodiment, a projection type video display device that projects onto a screen like a transmission type projector has been described as an example. However, the present invention is a direct view type video display device that directly looks at a liquid crystal display device. Also widely applicable.

It is a figure for demonstrating the structure of the liquid crystal drive circuit of the active matrix type liquid crystal display device which is an example of the liquid crystal display device to which this invention is applied. It is a figure for demonstrating the modification of the liquid crystal drive circuit shown in FIG. It is FIG. (1) for demonstrating an example of the manufacturing method of the liquid crystal display device to which this invention is applied. It is FIG. (2) for demonstrating an example of the manufacturing method of the liquid crystal display device to which this invention is applied. It is FIG. (1) for demonstrating another example of the manufacturing method of the liquid crystal display device to which this invention is applied. It is FIG. (2) for demonstrating another example of the manufacturing method of the liquid crystal display device to which this invention is applied. It is a figure for demonstrating the reduction | decrease of the area | region where incident light hits an LDD area | region directly. It is a schematic diagram for demonstrating the transmissive liquid crystal projector which is an example of the video display apparatus to which this invention is applied. It is a figure for demonstrating the structure of the liquid crystal drive circuit of the conventional active matrix type liquid crystal display device. It is a schematic diagram for demonstrating the alternating current drive of a video signal. It is a schematic diagram for demonstrating the VGS-IDS characteristic of TFT. It is a schematic diagram for demonstrating the amount of voltage changes. It is a schematic diagram for demonstrating TFT in the conventional liquid crystal display device. It is a schematic diagram for demonstrating an example of refinement | miniaturization of TFT.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Video line 2 Horizontal scanning circuit 3 Level conversion circuit 4 Vertical scanning circuit 5 Gate electrode 6 Channel area 7 Source area 8 Data line side LDD area 9 Drain area 10 Pixel electrode side LDD area 11 Quartz substrate 12 Convex part 20 Quartz substrate 21 WSi Layer 22 SiO ₂ layer 23 channel polysilicon layer 24 gate oxide film 25 PDAS layer 26 SiO ₂ layer 27 contact hole 28 SiO ₂ layer 29 Ti layer 30 SiO ₂ layer 31 transparent electrode 32 polysilicon layer 33 SiO ₂ layer 34 conductive film DESCRIPTION OF SYMBOLS 100 Transmission type liquid crystal projector 101 Lamp 103R R dichroic mirror 103G G dichroic mirror 104R R light valve 104G G light valve 104B B light valve 105 Dichroic prism 106 Projection lens 1 7 a fly-eye lens 108 a polarization conversion element 109 filter 110 total reflection mirror 111 a relay lens 112 a condenser lens

Claims (8)

Pixel electrodes arranged in a matrix, a first source or drain region connected to the pixel electrode, a second source or drain region connected to a video signal, the first source or drain region and a channel region The first high resistance region and the second source or drain having the same conductivity type as that of the first source or drain region formed between the first source region and the drain region and higher resistance than the first source or drain region. Thin film transistor element having a second high resistance region which is of the same conductivity type as the second source or drain region formed between the region and the channel region and has a higher resistance than the second source or drain region A TFT substrate formed with
A counter substrate disposed facing the TFT substrate with a predetermined gap therebetween;
In a liquid crystal display device comprising a liquid crystal held in a gap between the TFT substrate and the counter substrate,
At least a part of at least one region of the first high resistance region or the second high resistance region is formed on a side surface of a concave portion or a convex portion provided in the TFT substrate. Liquid crystal display device. 2. The at least part of the first high resistance region and the second high resistance region is formed on a side surface of a concave portion or a convex portion provided in the TFT substrate. Liquid crystal display device. 2. The liquid crystal display device according to claim 1, wherein the first high resistance region and the second high resistance region are formed on a side surface of a concave portion or a convex portion provided in the TFT substrate. Pixel electrodes arranged in a matrix, a first source or drain region connected to the pixel electrode, a second source or drain region connected to a video signal, the first source or drain region and a channel region The first high resistance region and the second source or drain having the same conductivity type as that of the first source or drain region formed between the first source region and the drain region and higher resistance than the first source or drain region. Thin film transistor element having a second high resistance region which is of the same conductivity type as the second source or drain region formed between the region and the channel region and has a higher resistance than the second source or drain region A TFT substrate formed with
A counter substrate disposed facing the TFT substrate with a predetermined gap therebetween;
In a manufacturing method of a liquid crystal display device comprising a liquid crystal held in a gap between the TFT substrate and the counter substrate,
Forming a recess or a protrusion on the TFT substrate;
And a step of forming at least a part of at least one of the first high-resistance region and the second high-resistance region on a side surface of the concave portion or the convex portion. Production method. Pixel electrodes arranged in a matrix, a first source or drain region connected to the pixel electrode, a second source or drain region connected to a video signal, the first source or drain region and a channel region The first high resistance region and the second source or drain having the same conductivity type as that of the first source or drain region formed between the first source region and the drain region and higher resistance than the first source or drain region. Thin film transistor element having a second high resistance region which is of the same conductivity type as the second source or drain region formed between the region and the channel region and has a higher resistance than the second source or drain region A TFT substrate on which is formed,
A counter substrate disposed facing the TFT substrate with a predetermined gap therebetween;
A liquid crystal display device having a liquid crystal held in a gap between the TFT substrate and the counter substrate;
In a video display device that performs video display using light modulated by the liquid crystal display device,
At least a part of at least one region of the first high resistance region or the second high resistance region is formed on a side surface of a concave portion or a convex portion provided in the TFT substrate. Video display device. The at least part of the first high resistance region and the second high resistance region is formed on a side surface of a concave portion or a convex portion provided in the TFT substrate. Video display device. The video display device according to claim 5, wherein the first high resistance region and the second high resistance region are formed on a side surface of a concave portion or a convex portion provided in the TFT substrate. Pixel electrodes arranged in a matrix, a first source or drain region connected to the pixel electrode, a second source or drain region connected to a video signal, the first source or drain region and a channel region The first high resistance region and the second source or drain having the same conductivity type as that of the first source or drain region formed between the first source region and the drain region and higher resistance than the first source or drain region. Thin film transistor element having a second high resistance region which is of the same conductivity type as the second source or drain region formed between the region and the channel region and has a higher resistance than the second source or drain region A TFT substrate on which is formed,
A counter substrate disposed facing the TFT substrate with a predetermined gap therebetween;
A liquid crystal display device having a liquid crystal held in a gap between the TFT substrate and the counter substrate;
In a method of manufacturing a video display device that performs video display using light modulated by the liquid crystal display device,
Forming a recess or a protrusion on the TFT substrate;
A step of forming at least a part of at least one of the first high-resistance region or the second high-resistance region on a side surface of the concave portion or the convex portion. Production method.

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