JP5374875B2 - Electro-optic substrate, electro-optic device, electro-optic substrate design method, and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that stray light from an oblique direction enters a channel portion of a thin film transistor to possibly generate a photo leakage current and this phenomenon becomes remarkable when, particularly, a high-luminance optical system is used to cause a decrease in picture quality. <P>SOLUTION: The penetration depth of the stray light penetrating an optical waveguide is expressed by expression of t&lt;(0.61&times;&lambda;)/(n&times;sin&theta;<SB>c2</SB>), where t (nm) is the layer thickness of a first insulating layer 5, n is the refraction index, and &theta; is the penetration angle of the stray light. If &lambda; is 400 (nm) which is the shortest wavelength of visible light, the condition that should be satisfied by a distance L<SB>c2</SB>(nm) between a shielding layer end and a channel region end becomes nt<SP>2</SP>&lt;244L<SB>c2</SB>. The layer thickness of the first insulating layer 5 and the distance between the shielding layer end and channel region end are controlled so that the expression may be satisfied, thereby suppressing a decrease in picture quality due to penetration of the oblique stray light. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to an electro-optical substrate, an electro-optical device, an electro-optical substrate design method, and an electronic apparatus.

  A liquid crystal panel as an electro-optical device used in an electronic apparatus such as a projector receives light from one surface of the liquid crystal panel, for example, and spatially modulates the light. The spatially modulated light is emitted from the other surface of the liquid crystal panel to form an image or character pattern. Here, a structure in which a light shielding layer is provided between the thin film transistor and the light source of the light is used in order to suppress the occurrence of light leakage current that occurs when this light enters the channel region of the thin film transistor that drives the liquid crystal panel. ing.

  Further, for example, light incident from one surface of the liquid crystal panel may generate stray light due to reflection from the other surface of the liquid crystal panel, and the stray light may enter the semiconductor layer of the thin film transistor. In order to prevent such stray light from entering the thin film transistor, a structure in which another light shielding layer is provided between the thin film transistor and the second surface of the electro-optical substrate is used. This separate light shielding layer prevents stray light from entering the semiconductor layer of the thin film transistor directly.

  In recent years, SOI technology has been studied in response to the demand for shortening the writing time per pixel accompanying the increase in the number of pixels of a display device and increasing the contrast. By using SOI technology, a single crystal thin film transistor with high mobility can be used instead of a polycrystalline thin film transistor, and high-speed switching is possible. A manufacturing method for obtaining a light-shielding layer on the side close to the substrate using the SOI technology is described in Patent Document 1, for example. In this manufacturing method, a light-shielding layer is formed on the surface of a light-transmitting substrate, covered with a silicon oxide layer and flattened by polishing, and a single crystal silicon substrate is bonded to the flat surface to leave a single crystal silicon thin layer. Thus, a substrate having SOI is formed except for a single crystal silicon substrate.

JP-A-10-293320

  Inside a display device using a liquid crystal panel, there is irregularly reflected light from many optical components and components, and other than light that is incident perpendicular to the electro-optic substrate on which the thin film transistor is formed, it is oblique as stray light. The intensity of the light that enters the light is increasing. Particularly in recent years, the brightness of the light source has been increased in order to obtain a brighter image, and the intensity of stray light entering the thin film transistor tends to increase. In order to prevent deterioration in display image quality due to generation of light leakage current due to stray light, an electro-optical substrate having sufficient light shielding performance against this stray light entering obliquely is necessary.

  In addition, when a single crystal silicon layer having excellent crystallinity is used as a semiconductor included in the thin film transistor (for example, an SOI structure), carriers such as electrons and holes generated by excitation due to stray light penetration hardly recombine. Therefore, in order to suppress the occurrence of light leakage current that passes between the source and drain of the semiconductor element due to the intrusion of stray light, a higher light shielding property is required compared to the case of using a polycrystalline silicon layer. According to the investigation of the present inventor, the amount of light leakage current increases about 10 times in the case of a single crystal silicon layer compared to the case of using a polycrystalline silicon layer with many crystal defects, and the display image quality is deteriorated. There is a problem of inviting.

  In order to solve the above-described problems, the present invention provides an electro-optic substrate, an electro-optic device, an electro-optic substrate design method, and an electronic apparatus having a thin film transistor in which generation of light leakage current is suppressed. Objective.

  In the present application, “upper” is defined as a direction away from an object constituting the substrate through the first surface of the substrate. An “opening” is defined as a portion that contributes to display in a region overlapping with a pixel electrode.

In order to solve the above problems, an electro-optical substrate according to the present invention includes a substrate, a thin film transistor disposed on a first surface of the substrate, and a first light-shielding layer disposed between the substrate and the thin film transistor. And a first insulating layer disposed between the thin film transistor and the first light-shielding layer, having a refractive index of n and a layer thickness of t (nm), and the thin film transistor includes the first thin film transistor When a portion where the gate electrode and the semiconductor layer overlap in a plan view as viewed from the normal direction of the surface is a channel, one of a plurality of end portions of the channel in a cross section along the length direction of the channel The positional relationship between a certain first channel end and a first light shielding end that is an end closer to the first channel end among the plurality of ends of the first light shielding layer is Between one channel end and the first shading end Using _L c1 (nm) which is away, satisfies the relational ^expression, nt 2 <244L _c1, and, in a cross section along the width direction of the channel is one of a plurality of ends of the channel, the The positional relationship between the two-channel end portion and the second light-shielding end portion that is the end portion closer to the second channel end portion among the plurality of end portions of the first light-shielding layer is the second channel end portion. And the second light-shielding end portion are arranged so as to satisfy the relational expression, nt ² <244L _c2 , using L _c2 (nm) which is the distance between the second light-shielding end portion and the second light-shielding end portion .
The electro-optic substrate according to the present invention includes a substrate, a thin film transistor disposed on a first surface of the substrate, a first light-shielding layer disposed between the substrate and the thin film transistor, the thin film transistor, and the thin film transistor. A first insulating layer disposed between the first light-shielding layer and having a refractive index of n and a layer thickness of t (nm), wherein the thin film transistor is in a normal direction of the first surface A cross section along the length direction of the channel when a portion where the gate electrode and the semiconductor layer overlap in a plan view as viewed from above is a channel and a portion between the channel and the source / drain of the semiconductor layer is an LDD The first channel end portion, which is one of the plurality of end portions of the channel, and the end portion on the side closer to the first channel end portion among the plurality of end portions of the first light shielding layer. Positional relationship with one light-shielding end , Using _L c1 (nm) is the distance between the first light blocking end portion and the first channel end, ^{relationship,} nt 2 <meet 244L _c1, and a plurality of end portions of the LDD of the first 1LDD end is an end portion on the side closer to the first light blocking end, the positional relationship, the distance between the first light-shielding end the first 1LDD end L _l1 ( nm), and is arranged so as to satisfy the relational expression, nt ² <244L ₁₁ .
The electro-optic substrate according to the present invention includes a substrate, a thin film transistor disposed on a first surface of the substrate, a first light-shielding layer disposed between the substrate and the thin film transistor, the thin film transistor, and the thin film transistor. A first insulating layer disposed between the first light-shielding layer and having a refractive index of n and a layer thickness of t (nm), wherein the thin film transistor is in a normal direction of the first surface When a portion where the gate electrode and the semiconductor layer overlap in a plan view as viewed from above is a channel and a portion between the channel and the source / drain of the semiconductor layer is an LDD, in a cross section along the width direction of the channel A second channel end that is one of a plurality of ends of the channel, and a second end that is closer to the second channel end of the plurality of ends of the first light shielding layer. The positional relationship with the shading edge is Using _L c2 (nm) is the distance between the second light blocking end portion and the second channel end, satisfies the relational ^expression, nt 2 <244L _c2, and, and parallel to the width direction of the channel In the cross section including the LDD, the second LDD end portion, which is one of the plurality of end portions of the LDD, and the end portion closer to the second LDD end portion among the plurality of end portions of the first light shielding layer in a third light blocking end, the positional relationship, using _L l2 (nm) is the distance between the third light-blocking ends the first 2LDD end ^{relationship,} nt 2 <244L _l2 It is arrange | positioned so that it may satisfy | fill.
In addition, the electro-optic substrate according to the reference invention of the present invention includes a transparent substrate, a first light shielding layer disposed on at least a part of a region surrounding the opening portion in a plan view on the first surface side of the transparent substrate, A first layer having a refractive index n and a layer thickness t (nm) that covers at least a part of the first light-shielding layer in a plan view and is disposed at a position facing the transparent substrate with the first light-shielding layer interposed therebetween. An insulating layer; and a portion of the thin film transistor that is disposed at a position facing the transparent substrate with the first insulating layer interposed therebetween, the channel region being located inside the first light shielding layer in plan view, and the first A semiconductor layer in which a distance L _c (nm) between a light-shielding layer end and the channel region end satisfies nt ² <244L _c (relational expression 1), a gate insulating layer covering the channel region, Placed in a region facing the channel region with the gate insulating layer in between And a second insulating layer disposed at a position covering at least the gate electrode, and a second insulating layer provided at a position facing the semiconductor layer with the second insulating layer interposed therebetween so as to cover at least the channel region. And 2 light-shielding layers.

According to this configuration, the penetration depth of the stray light is set such that the wavelength of the stray light is λ (nm), the thickness of the first insulating layer (corresponding to the light guide layer) is t (nm), and the refractive index of the first insulating layer is n, where the stray light penetration angle is θ, it is expressed by the following equation according to the Rayleigh diffraction limit relationship.
t <(0.61 × λ) / (n × sin θ) (Relational Expression 5).
In this case, since the smaller λ is a severe condition with respect to t, λ is set to 400 nm which is the shortest wavelength of visible light. When sin θ (opposite side / slope side) is expressed using a distance L _c (nm) between the first light shielding layer end and the channel region end, L _{c corresponds} to the length of the hypotenuse and the thickness of the light guide layer corresponds to t. Therefore, sin θ = t / L _c . Substituting this correspondence into relational expression 5 leads to nt ² <244L _c (relational expression 1).

  By taking the positional relationship of the channel region so as to satisfy the relational expression 1, the end of the channel region can be disposed at a position exceeding the stray light penetration limit. Therefore, it is possible to suppress the occurrence of light leakage current derived from stray light to the channel region. By suppressing the occurrence of light leakage current derived from stray light, it is possible to suppress the occurrence of noise derived from stray light, and to provide an electro-optic substrate with high image quality.

In the electro-optical substrate according to the present invention, the thin film transistor includes an LDD region, a distance L _c between the first light shielding layer end and the channel region end satisfies the relational expression 1, and the first light shielding. It includes a semiconductor layer in which a distance L _l (nm) between the layer end and the LDD region end satisfies nt ² <244L _l (relational expression 2).

According to this configuration, the channel region and the LDD region are disposed at a position exceeding the penetration depth of stray light. By giving the positional relationship of the channel region so as to satisfy nt ² <244L _c (Relational Formula 1) and nt ² <244L _l (Relational Formula 2), the channel region and the LDD region are positioned beyond the stray light penetration limit. Can be arranged. Therefore, it is possible to suppress the occurrence of light leakage current resulting from the entry of stray light into the channel region and the occurrence of light leakage current resulting from the entry of stray light into the LDD region. Since generation of light leakage current derived from stray light is suppressed even in the LDD region, generation of noise derived from stray light can be suppressed, and an electro-optic substrate with higher image quality can be provided.

The electro-optic substrate according to the present invention includes a substrate, a thin film transistor disposed on a first surface of the substrate, a first light-shielding layer disposed between the substrate and the thin film transistor, the thin film transistor, and the thin film transistor. A first insulating layer disposed between the first light-shielding layer and having a refractive index of n and a layer thickness of t (nm), wherein the thin film transistor is in a normal direction of the first surface When a portion where the gate electrode and the semiconductor layer overlap in a plan view as viewed from above is a channel and a portion between the channel and the source / drain of the semiconductor layer is an LDD, in a cross section along the width direction of the channel A second channel end that is one of a plurality of ends of the channel, and a second end that is closer to the second channel end of the plurality of ends of the first light shielding layer. The positional relationship with the shading edge is A perpendicular drawn from the second channel end to the first light-shielding layer, the second light blocking end, X _c and _(nm) is the shortest distance between the shortest wavelength of light incident on the substrate Satisfying the relational expression, t (n ² t ² −0.3721λ ² ) ^0.5 <0.61λX _c ² , and parallel to the width direction of the channel, and In a cross section including the LDD, a second LDD end portion, which is one of a plurality of end portions of the LDD, and an end portion closer to the second LDD end portion among the plurality of end portions of the first light shielding layer. X _l (nm) is the shortest distance between the perpendicular line extending from the second LDD end portion to the first light shielding layer and the third light shielding end portion. using relational ^{expression, t (n 2 t 2 -0.3721λ} 2) 0.5 <0.61λX l 2 Characterized in that it is arranged to satisfy.
In the electro-optic substrate according to the present invention, the first light shielding layer has a thickness of 100 to 1000 nm, and the first insulating layer has a thickness t of less than 285 nm.
In addition, the electro-optic substrate according to the reference invention of the present invention includes a transparent substrate, a first light shielding layer disposed on at least a part of a region surrounding the opening portion in a plan view on the first surface side of the transparent substrate, A first insulation having a refractive index n and a layer thickness t (nm) that covers at least a part of the first light-shielding layer in a plan view and is disposed at a position facing the transparent substrate with the first light-shielding layer interposed therebetween. A channel region including a part of a thin film transistor located inside the first light shielding layer in a plan view, and disposed in a position facing the transparent substrate with the first insulating layer interposed therebetween, and the first light shielding When the distance between the layer end and the perpendicular from the channel region end to the first light shielding layer is X _c (nm) and the shortest wavelength of light incident on the transparent substrate is λ (nm), ^{t (n 2 t 2 -0.3721λ 2} ) 0.5 <0.61λX c 2 ··· ( A semiconductor layer satisfying Equation 3), a gate insulating layer covering the channel region, a gate electrode sandwiching the gate insulating layer and disposed in a region facing the channel region, and at least a position covering the gate electrode And a second light-shielding layer provided at a position facing the semiconductor layer with the second insulating layer interposed therebetween so as to cover at least the channel region.

  In this configuration, the penetration depth of the stray light is λ (nm) as the wavelength of stray light, t (nm) as the layer thickness of the first insulating layer (corresponding to the light guide layer), n as the refractive index of the first insulating layer, When the stray light penetration angle is θ, it is expressed by the following equation.

t <(0.61 × λ) / (n × sin θ) (Relational Expression 5). In this case, λ is the shortest wavelength incident on the substrate. When the distance between the end of the first light-shielding layer and the perpendicular to the first light-shielding layer from the end of the channel region to the first light-shielding layer is represented by X _c (nm), (X _c ² + t ² ) ^0.5 is the hypotenuse. The opposite side corresponds to the layer thickness of the light guide layer t (nm). Therefore, sin θ = t / (X _c ² + t ² ) ^0.5 . Substituting this correspondence into relational expression 5, the following relational expression is obtained.
t (n ² t ² −0.3721λ ² ) ^0.5 <0.61λX _c ² (Relational Expression 3).

  By arranging the channel region so as to satisfy the relational expression 3, the end of the channel region can be arranged at a position beyond the stray light penetration limit. Therefore, it is possible to suppress the occurrence of light leakage current derived from stray light to the channel region. By suppressing noise derived from stray light, an electro-optic substrate with high image quality can be provided.

In the electro-optic substrate according to the present invention, the thin film transistor includes an LDD region, a distance L _c between the first light shielding layer end and the channel region end satisfies the relational expression 3, and the first light shielding. When the distance between the layer edge and the perpendicular from the LDD region edge to the first light shielding layer is X _l (nm) and the shortest wavelength of light incident on the transparent substrate is λ (nm), It includes a semiconductor layer satisfying t (n ² t ² −0.3721λ ² ) ^0.5 <0.61λX _l ² (Relational Expression 4).

In this configuration, the penetration depth of the stray light is λ (nm) as the wavelength of stray light, t (nm) as the layer thickness of the first insulating layer (corresponding to the light guide layer), n as the refractive index of the first insulating layer, When the stray light penetration angle is θ, it is expressed by the following equation.
t <(0.61 × λ) / (n × sin θ) (Relational Expression 5).
In this case, λ is the shortest wavelength incident on the substrate. Then, when sin θ (opposite side / slope side) is expressed as X _l (nm) between the first light shielding layer end and the perpendicular line from the LDD region end to the first light shielding layer, (X _l ² + t ² ) ^0.5 is the hypotenuse. Since the thickness of the light guide layer corresponds to t (nm) on the opposite side, sin θ = t / (X ₁ ² + t ² ) ^0.5 . By using this correspondence relationship, the following expression is obtained.
t (n ² t ² −0.3721λ ² ) ^0.5 <0.61λX ₁ ² (Relational Expression 4).
By arranging the positions of the channel region and the LDD region so as to satisfy the relational expression 3 and the relational expression 4, the channel region end and the LDD region end can be arranged at positions exceeding the stray light penetration limit. Therefore, it is possible to suppress the occurrence of light leakage current resulting from the stray light entering the channel region and the LDD region. By suppressing noise derived from stray light, an electro-optic substrate with high image quality can be provided.

The electro-optic substrate design method according to the present invention is a design method of an electro-optic substrate having a substrate, a thin film transistor, a first light-shielding layer, and a first insulating layer, wherein the thin film transistor is a first of the substrate. The first light shielding layer is disposed between the substrate and the thin film transistor, the first insulating layer is disposed between the thin film transistor and the first light shielding layer, and has a refractive index of n. And the layer thickness is t (nm), and the thin film transistor has a channel where a portion where the gate electrode and the semiconductor layer overlap in a plan view as viewed from the normal direction of the first surface is a channel. In the cross section along the length direction of the channel, the first channel end portion among the first channel end portion and the plurality of end portions of the first light shielding layer, which is one of the plurality of end portions of the channel. Near end There are a first light-shielding end, the positional relationship, using _L c1 (nm) is the distance between the first channel end the first light blocking end ^{relationship,} nt 2 <244L _c1 And in a cross section along the width direction of the channel, among the second channel end portion and the plurality of end portions of the first light shielding layer, which is one of the plurality of end portions of the channel, L _c2 (nm), which is the distance between the second channel end and the second light-shielding end, relative to the second light-shielding end that is the end closer to the second channel end And is arranged so as to satisfy the relational expression, nt ² <244L _c2 .
The electro-optic substrate design method according to the present invention is a design method of an electro-optic substrate having a substrate, a thin film transistor, a first light-shielding layer, and a first insulating layer, wherein the thin film transistor is a first of the substrate. The first light shielding layer is disposed between the substrate and the thin film transistor, the first insulating layer is disposed between the thin film transistor and the first light shielding layer, and has a refractive index of n. And the layer thickness is t (nm), and the thin film transistor uses the portion where the gate electrode and the semiconductor layer overlap in a plan view as viewed from the normal direction of the first surface as a channel, and the semiconductor layer A portion between the channel and the source / drain of the first channel end portion, which is one of a plurality of end portions of the channel in a cross section along the length direction of the channel, Among the plurality of end portions of the first light shielding layer, the positional relationship with the first light shielding end portion which is the end portion on the side close to the first channel end portion is the first channel end portion and the first light shielding portion. Using L _c1 (nm) which is the distance between the ends , the relational expression, nt ² <244L _c1 is satisfied, and among the plurality of ends of the LDD, the side closer to the first light shielding end of a first 1LDD end is an end, the positional relationship, using a _L l1 (nm) is the distance between the first light-shielding end the first 1LDD end relationship, ^nt 2 < It is arranged to satisfy 244L ₁₁ .
Further, the electro-optic substrate design method according to the reference invention of the present application includes a transparent substrate and a first light shielding element disposed on at least a part of a region surrounding the opening in a plan view on the first surface side of the transparent substrate. A refractive index n and a layer thickness t (nm) that are disposed at a position that covers at least a part of the first light-shielding layer in plan view and that faces the transparent substrate with the first light-shielding layer interposed therebetween. Design of an electro-optical substrate including a first insulating layer and a thin film transistor disposed at a position facing the transparent substrate with the first insulating layer interposed therebetween and having a channel region positioned inside the first light shielding layer in plan view The method is characterized in that the distance Lc (nm) between the end portion of the first light-shielding layer and the end portion of the channel region is designed to satisfy nt2 <244Lc (Relational Expression 1).

By using this design method, the channel region can be designed to be disposed at a position exceeding the penetration depth of stray light. Furthermore, the light leakage current can be effectively reduced by designing _Lc or the like, which is a function of the distance between the first light shielding layer and the channel region, so as to satisfy the above relational expression.

The electro-optic substrate design method according to the present invention includes a transparent substrate, and a first light-shielding layer disposed on at least a part of a region surrounding the opening in a plan view on the first surface side of the transparent substrate. , Having a refractive index n and a layer thickness t (nm), which covers at least a part of the first light shielding layer in a plan view, and is disposed at a position facing the transparent substrate with the first light shielding layer interposed therebetween. An electro-optical substrate including one insulating layer and a portion of a thin film transistor that is disposed at a position facing the transparent substrate with the first insulating layer interposed therebetween, and in which a channel region is positioned inside the first light shielding layer in plan view A design method, wherein a distance between an end portion of the first light shielding layer and a perpendicular line extending from the end portion of the channel region to the first light shielding layer is X _c (nm), and the shortest light incident on the transparent substrate When the wavelength is λ (nm), t (n ² t ² −0.3721λ ² ) ^0.5 <0.61λX _c ² (Relational expression 3).

By using this design method, it is possible to design the channel region to be disposed at a position exceeding the penetration depth of stray light according to the shortest wavelength of incident light. Furthermore, the optical leakage current can be effectively reduced by designing so as to satisfy the above relational expression which is a function of the distance _Xc between the end of the first light-shielding layer and the end of the channel region to the perpendicular drawn to the first light-shielding layer. Can do.

The electro-optic substrate design method according to the present invention includes a transparent substrate, and a first light-shielding layer disposed on at least a part of a region surrounding the opening in a plan view on the first surface side of the transparent substrate. , Having a refractive index n and a layer thickness t (nm), which covers at least a part of the first light shielding layer in a plan view, and is disposed at a position facing the transparent substrate with the first light shielding layer interposed therebetween. A method of designing an electro-optic substrate including one insulating layer and a thin film transistor that is disposed at a position facing the transparent substrate with the first insulating layer interposed therebetween, and an LDD region is located inside the first light shielding layer in a plan view. Therefore, the distance L _l (nm) between the end portion of the first light shielding layer and the end portion of the LDD region is designed to satisfy nt ² <244L _l (relational expression 2).

By using this design method, the LDD region can be designed to be disposed at a position exceeding the penetration depth of stray light. Furthermore the L _l or the like as a function of the distance between the first light-shielding layer and the LDD region can be effectively reduce light leakage current can be designed to meet the above relationship.

The electro-optic substrate design method according to the present invention includes a transparent substrate, and a first light-shielding layer disposed on at least a part of a region surrounding the opening in a plan view on the first surface side of the transparent substrate. , Having a refractive index n and a layer thickness t (nm), which covers at least a part of the first light shielding layer in a plan view, and is disposed at a position facing the transparent substrate with the first light shielding layer interposed therebetween. An electro-optic substrate including one insulating layer and a portion of the thin film transistor that is disposed at a position facing the transparent substrate with the first insulating layer interposed therebetween, and the LDD region is located inside the first light shielding layer in a plan view. A design method, wherein a distance between an end of the first light-shielding layer and a perpendicular drawn from the end of the LDD region to the first light-shielding layer is X _l (nm), and the shortest light incident on the transparent substrate When the wavelength is λ (nm), t (n ² t ² −0.3721λ ² ) ^{0. 5} <0.61λX _l ² (Designed to satisfy the relational expression 4).

By using this design method, the LDD region can be designed to be disposed at a position exceeding the penetration depth of stray light according to the shortest wavelength of incident light. Effectively reducing the light leakage current can be designed to meet the more the relation is a function of the distance X _l of the perpendicular dropped to the first light-shielding layer from the first light-shielding layer end and the ends of the channel region Can do.

  In addition, an electro-optical device according to the present invention includes the above-described electro-optical substrate.

  According to this configuration, it is possible to provide an electro-optical device that can display with high luminance because it includes the electro-optical substrate in which generation of light leakage current due to stray light is suppressed.

  According to another aspect of the invention, an electronic apparatus includes the electro-optical device described above.

  According to this configuration, since the electro-optical device capable of displaying with high luminance is included, it is possible to provide an electronic apparatus having a display unit with excellent visibility.

(First embodiment)
The first embodiment will be described below with reference to the drawings. FIG. 1 is a plan view of an electro-optical substrate 220 including a thin film transistor 205. The thin film transistor 205 is driven through the signal wiring 12 and the gate wiring 6. The drain electrode 8 is connected to a pixel electrode 19 using, for example, ITO, and controls the potential of the pixel electrode 19.

  FIG. 2 is a cross-sectional view taken along the line AA of FIG. A quartz substrate 1 as a transparent substrate is provided with a first light shielding layer 4 using tungsten silicide. As the layer thickness of the first light shielding layer 4, for example, a layer thickness of about 100 to 1000 nm can be used. Here, as the material of the first light shielding layer 4, a metal that can withstand the maximum temperature for forming the electro-optic substrate 220, such as molybdenum, tungsten, or tantalum, polycrystalline silicon, molybdenum silicide, or the like can be used instead of tungsten silicide.

  A first insulating layer 5 using silicon oxide is disposed so as to cover the first light shielding layer 4. The thickness of the first insulating layer 5 is t (nm), the refractive index is n, and when silicon oxide is used for the first insulating layer 5, n is typically 1.5. The thin film transistor 205 is disposed so as to cover a part of the first insulating layer 5 and include the channel region 200 located inside the first light shielding layer 4 in a plan view.

  The thin film transistor 205 includes a channel region 200 using the silicon layer 2, and an LDD region 201 and a source / drain region 202 disposed on both sides of the channel region 200. The gate electrode 3 is disposed with the gate insulating layer 14 interposed therebetween. Here, polysilicon is used as the material of the gate electrode 3. Here, instead of polysilicon, a material having conductivity that can withstand the maximum temperature in the process after forming the gate electrode 3 for forming the thin film transistor 205 can be used as the material of the gate electrode 3. Specifically, a substance such as tungsten silicide, molybdenum, tungsten, tantalum, or molybdenum silicide can be used. As the gate insulating layer 14, for example, silicon oxide can be used.

  A first interlayer insulating layer 15 as a second insulator layer using silicon oxide is disposed at a position covering the channel region 200, the LDD region 201, the source / drain region 202, and the gate electrode 3 of the thin film transistor 205. A drain electrode 8 and a source electrode 9 are formed so as to penetrate the first interlayer insulating layer 15 and the gate insulating layer 14 and connect to the source / drain region 202. Further, the second interlayer insulating layer 10 is located so as to cover the first interlayer insulating layer 15.

In the region where the drain electrode 8 of the second interlayer insulating layer 10 is located, the drain electrode 8 and the pixel electrode 19 are arranged so as to overlap each other so that the drain electrode 8 and the pixel electrode 19 are electrically connected. Here, the silicon layer 2 can be a polysilicon layer obtained by modifying amorphous silicon. Alternatively, a single crystal silicon layer using a bonding method or the like may be used.

  Further, instead of the first light shielding layer 4 using black polyimide resin, a configuration in which at least the channel region 200 of the thin film transistor 205 is shielded by using the drain wiring 11 may be used. In this case, compared with the case where a black polyimide resin is used, the light shielding region can be formed more precisely, so that a higher aperture ratio can be obtained.

Next, an optical waveguide mechanism when stray light enters the channel region 200 of the thin film transistor 205 at the entrance angle θ _c2 will be described with reference to FIG. 3 is a cross-sectional view taken along line BB in FIG. In FIG. 3, portions that are not related to the propagation of stray light are omitted. As shown in FIG. 3, when stray light enters the thin film transistor 205 at the entrance angle θ _c2 , an optical waveguide is formed by the first light shielding layer 4, the first insulating layer 5, and the channel region 200 (silicon layer 2). It becomes a state. The penetration depth of stray light that can enter the optical waveguide is expressed by the following equation, where the thickness of the first insulating layer 5 is t (nm), the refractive index is n, and the stray light penetration angle is θ _c2. .
t <(0.61 × λ) / (n × sin θc ₂ ) (Relational expression 5a).
In the relational expression 5a, sin θ _c2 is the opposite side / slope side. This relationship can be described as (layer thickness t (nm)) / (distance L _c2 (nm), where λ is 400 nm which is the shortest wavelength of visible light, layer thickness is t (nm)), and distance is L _c2 If (nm), the condition to be satisfied by L _c2 is the same as the relational expression 1, and can be expressed by nt ² <244L _c2 .

As a typical value, when the first insulating layer 5 is silicon oxide having a refractive index of 1.5 and the distance L _c2 (nm) to the channel region 200 is suppressed to, for example, less than 500 nm, The allowable layer thickness of the insulating layer 5 can be calculated. In this case, stray light can be prevented from entering the channel region 200 by setting the first insulating layer 5 to a layer thickness of less than 285 nm. Then, the invasion of stray light from the length direction of the thin film transistor 205 can be suppressed by satisfying the same relationship with respect to the distance L _c1 (nm) illustrated in FIG. Note that, as shown in FIG. 2, the structure in the case where the thin film transistor 205 includes the LDD region 201 has been described here. However, in the case of adopting this configuration, the LDD region 201 is not an essential component and can be omitted. .

In order to further suppress the dark current, in addition to the condition for suppressing the distance between the end of the channel region 200 and the end of the first light shielding layer 4 to L _c1 (nm) and L _c2 (nm), FIG. Similarly, a method for suppressing the intrusion of stray light can be used for the end portion of the LDD region 201 shown. Similar to the mechanism described above, as shown in FIG. 2, the distance L ₁₁ (nm) between the end of the LDD region 201 and the end of the first light shielding layer 4 satisfies nt ² <244L ₁₁ and C in FIG. Similarly, L _l2 (nm) shown in FIG. 7 , which is a cross-sectional view of −C, can suppress the entry of stray light into the LDD region 201 by arranging the LDD region 201 to satisfy nt ² <244L _l2 , Further, the dark current can be reduced.

(Third embodiment)
In the present embodiment, with respect to the refractive index n and the layer thickness t (nm) of the first insulating layer 5, the perpendicular line dropped from the end of the first light shielding layer 4 and the end of the channel region 200 to the first light shielding layer 4. The design of the distance _Xc (nm) and the shortest wavelength λ (nm) of light incident on the transparent substrate (electro-optic substrate) will be described.

FIG. 8 is a diagram illustrating a state in which stray light enters the channel region 200 of the thin film transistor 205 at the penetration angle θ _c as in FIG. 3. In order to prevent stray light from reaching the channel region 200, Rayleigh's From the diffraction limit equation, the following equation should be satisfied.
t <(0.61 × λ) / (n × sin θ _c ) (Relational expression 5b).
In the relational expression 5b, sin θ _c is the opposite side / slope side, and this relation can be described as (layer thickness t (nm)) / (distance (X _c ² + t ² ) ^0.5 (nm). By rearranging, the following formula can be obtained, where relational expression 1 is a formula when the wavelength λ is 400 nm.
nt ² <244L _c (Relational formula 1)
t (n ² t ² −0.3721λ ² ) ^0.5 <0.61λX _c ² (Relational Expression 3).

Thus, the layer thickness t of the first insulating layer 5 and the first light-shielding layer 4 so as to satisfy the above relational expression with respect to the shortest wavelength λ of the incident light and the refractive index n of the first insulating layer 5. By controlling the distance _Xc between the end and the perpendicular line extending from the end of the channel region 200 to the first light shielding layer 4, stray light can be prevented from entering the channel region 200, and noise derived from stray light can be suppressed. Thus, an electro-optic substrate with high image quality can be provided.

In designing the thin film transistor of this embodiment, it is preferable to select t, L _c , and X _c so as to satisfy the relations of the relational expressions 1 and 3. For example, when the area per pixel advances with the increase in definition of the electro-optic substrate and L _c or X _c decreases, the layer thickness t of the first insulating layer 5 is expressed by the relational expression 1 or the relational expression 3 The light-shielding property can be maintained by reducing the size so as to satisfy the above relationship.

(Fourth embodiment)
In the present embodiment, the perpendicular dropped from the end of the first light shielding layer 4 and the end of the LDD region 201 to the first light shielding layer 4 with respect to the refractive index n and the layer thickness t (nm) of the first insulating layer 5. The setting of X ₁ (nm) and the shortest wavelength λ (nm) of light incident on the transparent substrate (electro-optic substrate) will be described.

FIG. 9 is a diagram showing a state where stray light enters the LDD region 201 of the thin film transistor at the penetration angle θ _l as in FIG. 7. In order to prevent stray light from reaching the LDD region 201, Rayleigh diffraction is performed. From the limit formula, the following formula should be satisfied.
t <(0.61 × λ) / (n × sin θ _l ) (Relational Expression 5c).
In the relational expression 5c, sin θ _l is the opposite side / slope side, and this relation can be described as (layer thickness t (nm)) / (distance (X _l ² + t ² ) ^0.5 (nm). In summary, the following expression is obtained, where relational expression 2 is an expression when the wavelength λ is 400 nm.
nt ² <244L _l (Relational formula 2)
t (n ² t ² −0.3721λ ² ) ^0.5 <0.61λX ₁ ² (Relational Expression 4).
Thus, the layer thickness t of the first insulating layer 5 and the first light-shielding layer 4 so as to satisfy the above relational expression with respect to the shortest wavelength λ of the incident light and the refractive index n of the first insulating layer 5. by controlling the distance X _l between the end portion and the LDD region 201 perpendicular drawn from an end portion on the first light-shielding layer 4, the noise prevents it from entering the LDD region 201 of the stray light from the stray light is suppressed Thus, an electro-optic substrate with high image quality can be provided.

In designing the thin film transistor of this embodiment, it is preferable to select t, L _l , and X _l so as to satisfy the relations of the relational expressions 2 and 4. For example, when the area per pixel is reduced with the increase in definition of the electro-optic substrate, and L _l or X _l becomes smaller, the thickness t of the first insulating layer 5 is expressed by the relational expression 2 or the relational expression 4 The light-shielding property can be maintained by reducing the size so as to satisfy the above relationship. It can be said that the relational expression 2 and the relational expression 4 indicate the upper limit of the layer thickness t of the insulating layer.

(Fifth embodiment)
Hereinafter, as a fifth embodiment, a liquid crystal panel will be described as an electro-optical device including the above-described electro-optical substrate. As shown in FIG. 4 , a liquid crystal panel 30 having a display pixel region 27 on a quartz substrate 1 as a transparent substrate and having pixel electrodes 19 arranged in a matrix is used. Around the display pixel region 27, a drive circuit for processing a display signal is formed.
The gate line driving circuit 21 sequentially scans the gate signal wiring (not shown), and the data line driving circuit 22 supplies an image signal corresponding to the image data to the source signal wiring (not shown). Further, there are provided circuits such as an input circuit 23 for capturing image data inputted from the outside via the pad area 26, and a timing control circuit 24 for controlling these circuits.

Figure 5 is an A-A sectional view of a liquid crystal panel described in FIG. In the liquid crystal panel 30, a substrate 31 on which display pixels and a drive circuit are formed, and a transparent substrate 32 having a counter electrode 33 containing, for example, ITO as a transparent conductive layer are arranged at a constant interval. Then, a TN (Twisted_Nematic) type liquid crystal 34 or an SH (Super_Homeotropic) type liquid crystal in which liquid crystal molecules are aligned substantially vertically in a state where no voltage is applied is filled in a gap whose periphery is sealed with a sealing material 35. The above-described configuration is used for the liquid crystal panel 30 as an electro-optical device. In addition, the position where the sealing material 35 is provided is set so that the pad region 26 comes outside the sealing material 35 so that a signal can be input from the outside. Since the liquid crystal panel 30 prevents stray light from an oblique direction from entering at least the channel region 200 of the thin film transistor 205 as described above, the liquid crystal panel 30 is suitable for application when a high-intensity light source is used (high stray light intensity). A liquid crystal panel 30 as an optical device can be provided.

(Sixth embodiment)
Hereinafter, as a sixth embodiment, an electronic apparatus using a liquid crystal panel as the above-described electro-optical device will be described. FIG. 6 is a schematic diagram of a rear projector equipped with a liquid crystal panel as the electro-optical device described above as an electronic apparatus. The rear projector 230 uses the liquid crystal panel 30 as a light valve. Image information is given to the light supplied from the light source 231 by the liquid crystal panel 30. Then, the light beam is controlled by the optical system 232. Then, an image is displayed on the screen 235 by the reflecting mirror 233 and the reflecting mirror 234. The intensity of light entering the liquid crystal panel 30 used in the rear projector 230 is extremely high, and high image quality is required. Since the light intensity is extremely high, the intensity of the stray light is high. The liquid crystal panel 30 having the above-described configuration can suppress the influence of this stray light. Therefore, the rear projector 230 as an electronic device including the liquid crystal panel 30 can suppress the influence derived from stray light, and can realize high image quality of the output image. Other application fields besides the rear projector 230 include front projectors, mobile phones, video cameras, fax machines with display functions, digital camera finders, portable TVs, DSP devices, PDAs, electronic notebooks, electronic bulletin boards, advertising The present invention can also be applied to electronic devices such as a notification display and an IC card.

(Modification)
In the above-described embodiment, an example using a top gate type thin film transistor has been described. However, a bottom gate type thin film transistor may be used.

The top view of the electro-optical board | substrate containing a thin-film transistor. AA sectional drawing in alignment with the length direction of a channel. BB sectional drawing along the width direction of a channel. The top view of a liquid crystal panel as an electro-optical device. AA sectional view of a liquid crystal panel as an electro-optical device. Schematic diagram of a rear projector equipped with a liquid crystal panel. CC sectional drawing of the LDD area | region in alignment with the channel width direction of FIG. BB sectional drawing in the width direction of the channel of FIG. CC sectional drawing of the LDD area | region in alignment with the channel width direction of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Quartz substrate, 2 ... Silicon layer, 3 ... Gate electrode, 4 ... 1st light shielding layer, 5 ... 1st insulating layer, 6 ... Gate wiring, 8 ... Drain electrode, 9 ... Source electrode, 10 ... 2nd interlayer insulation Layer 11, drain wiring, 12 signal wiring, 14 gate insulating layer, 15 first interlayer insulating layer, 19 pixel electrode, 20 second light shielding layer, 21 gate line driving circuit, 22 data line driving Circuit, 23 ... Input circuit, 24 ... Timing control circuit, 26 ... Pad region, 27 ... Display pixel region, 30 ... Liquid crystal panel, 31 ... Substrate, 32 ... Transparent substrate, 33 ... Counter electrode, 34 ... TN type liquid crystal, 35 ... Sealing material, 200 ... Channel region, 201 ... LDD region, 202 ... Source / drain region, 205 ... Thin film transistor, 206 ... Buffer layer, 210 ... Dense layer, 220 ... Electro-optic substrate, 230 ... Rear projection , 231 ... light source, 232 ... optical system, 233 ... reflecting mirror, 234 ... reflecting mirror, 235 ... screen.

Claims (9)

A substrate,
A thin film transistor arranged on a first surface of the substrate,
A first light-shielding layer disposed between the substrate and the thin film transistor ;
Wherein disposed between the thin film transistor and the first light-shielding layer, a refractive index Ri n der has a layer thickness and a t (nm) Ru der first insulating layer, a
The thin film transistor,
When the first normal direction from the contact Keru gate electrode and the semiconductor layer in plan view seen overlap portion of the surface as a channel,
In a cross section along the length of the channel,
A first channel end that is one of a plurality of ends of the channel;
Among the plurality of end portions of the first light shielding layer, the positional relationship with the first light shielding end portion that is the end portion on the side close to the first channel end portion is :
Using L _c1 (nm) which is the distance between the first channel end and the first light shielding end,
Relational expression,
nt ² <244L _c1
It meets, and,
In a cross section along the width direction of the channel,
A second channel end that is one of a plurality of ends of the channel;
Of the plurality of end portions of the first light shielding layer, the positional relationship with the second light shielding end portion which is an end portion on the side close to the second channel end portion is
Using L _c2 (nm), which is the distance between the second channel end and the second light-shielding end ,
Relational expression,
nt ² <244L _c2
Electro-optical substrate characterized in that arranged on the meet Suyo. A substrate,
  A thin film transistor disposed on a first surface of the substrate;
  A first light-shielding layer disposed between the substrate and the thin film transistor;
  A first insulating layer disposed between the thin film transistor and the first light shielding layer, having a refractive index of n and a layer thickness of t (nm),
  The thin film transistor
  When a portion where the gate electrode and the semiconductor layer overlap in a plan view as viewed from the normal direction of the first surface is a channel, and a portion between the channel and the source / drain of the semiconductor layer is an LDD,
  In a cross section along the length of the channel,
  A first channel end that is one of a plurality of ends of the channel;
  Among the plurality of end portions of the first light shielding layer, the positional relationship with the first light shielding end portion that is the end portion on the side close to the first channel end portion is:
  L which is a distance between the first channel end and the first light shielding end _c1 (Nm)
  Relational expression,
  nt ²   <244L _c1
  And satisfy
  Among the plurality of end portions of the LDD, the positional relationship with the first LDD end portion which is the end portion on the side close to the first light shielding end portion is:
  L which is the distance between the first light-shielding end and the first LDD end _l1 (Nm)
  Relational expression,
  nt ²   <244L _l1
  An electro-optic substrate, which is arranged so as to satisfy the above. A substrate,
  A thin film transistor disposed on a first surface of the substrate;
  A first light-shielding layer disposed between the substrate and the thin film transistor;
  A first insulating layer disposed between the thin film transistor and the first light shielding layer, having a refractive index of n and a layer thickness of t (nm),
  The thin film transistor
  When a portion where the gate electrode and the semiconductor layer overlap in a plan view as viewed from the normal direction of the first surface is a channel, and a portion between the channel and the source / drain of the semiconductor layer is an LDD,
  In a cross section along the width direction of the channel,
  A second channel end that is one of a plurality of ends of the channel;
  Of the plurality of end portions of the first light shielding layer, the positional relationship with the second light shielding end portion which is an end portion on the side close to the second channel end portion is
  L which is the distance between the second channel end and the second light shielding end _c2 (Nm)
  Relational expression,
  nt ²   <244L _c2
  And satisfy
  In a cross section parallel to the width direction of the channel and including the LDD,
  A second LDD end, which is one of a plurality of ends of the LDD;
  Among the plurality of end portions of the first light shielding layer, the positional relationship with the third light shielding end portion which is the end portion on the side close to the second LDD end portion is
  L which is the distance between the third light-shielding end and the second LDD end _l2 (Nm)
  Relational expression,
  nt ²   <244L _l2
  An electro-optic substrate, which is arranged so as to satisfy the above. A substrate,
  A thin film transistor disposed on a first surface of the substrate;
  A first light-shielding layer disposed between the substrate and the thin film transistor;
  A first insulating layer disposed between the thin film transistor and the first light shielding layer, having a refractive index of n and a layer thickness of t (nm),
  The thin film transistor
  When a portion where the gate electrode and the semiconductor layer overlap in a plan view as viewed from the normal direction of the first surface is a channel, and a portion between the channel and the source / drain of the semiconductor layer is an LDD,
  In a cross section along the width direction of the channel,
  A second channel end that is one of a plurality of ends of the channel;
  Of the plurality of end portions of the first light shielding layer, the positional relationship with the second light shielding end portion which is an end portion on the side close to the second channel end portion is
X which is the shortest distance between the perpendicular line extending from the second channel end to the first light shielding layer and the second light shielding end _c (Nm)
Using λ (nm) which is the shortest wavelength of light incident on the substrate,
Relational expression,
t (n ² t ² -0.3721λ ² ) ^0.5   <0.61λX _c ²
  And satisfy
  In a cross section parallel to the width direction of the channel and including the LDD,
  A second LDD end, which is one of a plurality of ends of the LDD;
  Among the plurality of end portions of the first light shielding layer, the positional relationship with the third light shielding end portion which is the end portion on the side close to the second LDD end portion is
X, which is the shortest distance between a perpendicular line extending from the second LDD end portion to the first light shielding layer and the third light shielding end portion _l (Nm)
Relational expression,
t (n ² t ² -0.3721λ ² ) ^0.5   <0.61λX _l ²
  An electro-optic substrate, which is arranged so as to satisfy the above. The electro-optic substrate according to any one of claims 1 to 4,
  The first light shielding layer has a layer thickness of 100 to 1000 nm,
  The electro-optical substrate, wherein the first insulating layer has a layer thickness t of less than 285 nm.   A method for designing an electro-optic substrate having a substrate, a thin film transistor, a first light shielding layer, and a first insulating layer,
  The thin film transistor is disposed on a first surface of the substrate;
  The first light shielding layer is disposed between the substrate and the thin film transistor,
  The first insulating layer is disposed between the thin film transistor and the first light shielding layer, has a refractive index of n, and a layer thickness of t (nm),
  The thin film transistor
  When a portion where the gate electrode and the semiconductor layer overlap in a plan view viewed from the normal direction of the first surface is a channel,
  In a cross section along the length of the channel,
  A first channel end that is one of a plurality of ends of the channel;
  Among the plurality of end portions of the first light shielding layer, the positional relationship with the first light shielding end portion that is the end portion on the side close to the first channel end portion is:
  L which is a distance between the first channel end and the first light shielding end _c1 (Nm)
  Relational expression,
  nt ²   <244L _c1
  And satisfy
  In a cross section along the width direction of the channel,
  A second channel end that is one of a plurality of ends of the channel;
  Of the plurality of end portions of the first light shielding layer, the positional relationship with the second light shielding end portion which is an end portion on the side close to the second channel end portion is
  L which is the distance between the second channel end and the second light shielding end _c2 (Nm)
  Relational expression,
  nt ²   <244L _c2
  An electro-optic substrate design method, wherein the electro-optic substrate is arranged so as to satisfy the above.   A method for designing an electro-optic substrate having a substrate, a thin film transistor, a first light shielding layer, and a first insulating layer,
  The thin film transistor is disposed on a first surface of the substrate;
  The first light shielding layer is disposed between the substrate and the thin film transistor,
  The first insulating layer is disposed between the thin film transistor and the first light shielding layer, has a refractive index of n, and a layer thickness of t (nm),
  The thin film transistor
  When a portion where the gate electrode and the semiconductor layer overlap in a plan view as viewed from the normal direction of the first surface is a channel, and a portion between the channel and the source / drain of the semiconductor layer is an LDD,
  In a cross section along the length of the channel,
  A first channel end that is one of a plurality of ends of the channel;
  Among the plurality of end portions of the first light shielding layer, the positional relationship with the first light shielding end portion that is the end portion on the side close to the first channel end portion is:
  L which is a distance between the first channel end and the first light shielding end _c1 (Nm)
  Relational expression,
  nt ²   <244L _c1
  And satisfy
  Among the plurality of end portions of the LDD, the positional relationship with the first LDD end portion which is the end portion on the side close to the first light shielding end portion is:
  L which is the distance between the first light-shielding end and the first LDD end _l1 (Nm)
  Relational expression,
  nt ²   <244L _l1
  An electro-optic substrate design method, wherein the electro-optic substrate is arranged so as to satisfy the above. Electro-optical device which comprises an electro-optic substrate according to any one of claims 1 to 5. An electronic apparatus comprising the electro-optical device according to claim 8 .

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