JP2005010690A - Flat panel display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device wherein light detecting sensitivity of an optical sensor can be enhanced. <P>SOLUTION: The flat panel display device is so constituted that thickness of a glass substrate 12 of an array substrate 11 is specified to be 70 to 100 μm. Thereby, multiple reflection light of light made incident from the surface side of the glass substrate 12 can be satisfactorily attenuated. The optical sensor 21 is formed on the surface of the glass substrate 12. Thereby, incidence of light made incident from the surface side of the glass substrate 12 into the optical sensor 21 can be prevented, generation of excessive photocurrent of the optical sensor 21 caused by light made incident from the surface side of the glass substrate 12 can be prevented and light detecting sensitivity of the optical sensor 21 can be enhanced. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a flat display device including a switching element and a photoelectric conversion element.
[0002]
[Prior art]
2. Description of the Related Art In recent years, flat display devices such as liquid crystal displays have the great advantage of being thin and light and have low power consumption, and are widely used as displays for personal computers and mobile phones. Furthermore, the application of these flat display devices has been expanded by adding input functions such as touch panel and pen input to these flat display devices. However, in order to add these functions to the flat display device, it is necessary to add parts accompanying the addition of these functions, so that the total cost of the device including these flat display devices increases.
[0003]
On the other hand, a liquid crystal display device as a flat display device of this type incorporates a driving circuit, which has conventionally been an external component, into a surface that is one main surface of a glass substrate as a light-transmitting substrate on which switching elements are integrated. A technique for reducing the total cost of the liquid crystal display device has been developed. If the input function can be taken into the surface of the glass substrate by this technique, the total cost of the liquid crystal display device having the input function can be reduced and the added value can be improved.
[0004]
However, in order to realize a device having such an input function with an optical sensor as a photoelectric conversion element, it is necessary to efficiently receive light from a detection object with an optical sensor that generates a photocurrent by receiving incident light. I must.
[0005]
Therefore, this type of liquid crystal display device includes an array substrate having a glass substrate on which optical sensors are arranged and integrated on one main surface. The array substrate is arranged with the other main surface side of the glass substrate of the array substrate facing the detection object side detected by the optical sensor of the array substrate. In addition, a counter substrate is disposed opposite to one main surface of the array substrate, and liquid crystal is interposed between the counter substrate and the array substrate and sealed. Furthermore, a configuration is known in which a backlight is disposed to face the counter substrate (see, for example, Patent Document 1).
[0006]
[Patent Document 1]
Japanese Patent Laid-Open No. 10-333605 (page 3-5, FIG. 2)
[0007]
[Problems to be solved by the invention]
However, the optical sensor of the liquid crystal display device receives not only the light reflected by the detected object but also the stray light that is incident from the backlight by multiple reflections of the light incident on the glass substrate of the array substrate. The stray light causes a photocurrent to be generated by the optical sensor regardless of the light reflected from the detection object, and thus has a problem that it prevents the intensity of the light reflected by the detection object from being detected.
[0008]
This invention is made | formed in view of such a point, and it aims at providing the flat display apparatus which can improve the photodetection sensitivity of a photoelectric conversion element.
[0009]
[Means for Solving the Problems]
The present invention provides a light-transmitting substrate, a switching element and a photoelectric conversion element provided on one main surface of the light-transmitting substrate, and controlled by the switching element provided on one main surface of the light-transmitting substrate. A pixel electrode, and the translucent substrate has a thickness that prevents the light incident from one main surface side of the translucent substrate from being incident on the photoelectric conversion element due to multiple reflection. It is.
[0010]
The translucent substrate has a thickness that prevents light incident from one main surface side of the translucent substrate from being incident on the photoelectric conversion element due to multiple reflection. As a result, it is possible to prevent generation of an extra photocurrent of the photoelectric conversion element due to light incident from the one main surface side of the translucent substrate, and thus the light detection sensitivity of the photoelectric conversion element is improved.
[0011]
Further, the present invention provides a light-transmitting substrate, a switching element and a photoelectric conversion element provided on one main surface of the light-transmitting substrate, and controlled by the switching element provided on one main surface of the light-transmitting substrate. And a film body that is attached to the translucent substrate and prevents incident on the photoelectric conversion element due to multiple reflection of light incident from one main surface side of the translucent substrate. is there.
[0012]
And the film body attached to the translucent board | substrate can prevent the incident to the photoelectric conversion element by the multiple reflection of the light which injects from the one main surface side of the translucent board | substrate. For this reason, since generation of an excess photocurrent of the photoelectric conversion element due to light incident from one main surface side of the translucent substrate can be prevented, the light detection sensitivity of the photoelectric conversion element is improved.
[0013]
Furthermore, the present invention provides a translucent substrate, a switching element and a photoelectric conversion element provided on one main surface of the translucent substrate, and controlled by the switching element provided on one main surface of the translucent substrate. The translucent substrate has a refractive index that prevents light incident from one main surface side of the translucent substrate from being incident on the photoelectric conversion element due to multiple reflection. Is.
[0014]
The light-transmitting substrate has a refractive index that prevents light incident from one main surface side of the light-transmitting substrate from entering the photoelectric conversion element due to multiple reflection. As a result, it is possible to prevent generation of an extra photocurrent of the photoelectric conversion element due to light incident from the one main surface side of the translucent substrate, and thus the light detection sensitivity of the photoelectric conversion element is improved.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the configuration of the first embodiment of the flat display device of the present invention will be described with reference to FIGS.
[0016]
1 to 3, reference numeral 1 denotes a liquid crystal display device as a flat display device, and the liquid crystal display device 1 includes a substantially rectangular flat liquid crystal cell 2 as a pixel portion as shown in FIG. The liquid crystal cell 2 is an active matrix type with an input function. A pixel unit 3 as a display unit is provided on the surface that is one main surface of the liquid crystal cell 2. The pixel unit 3 has a light input function for capturing an image and the like, and displays the captured image. Further, the pixel portion 3 has a rectangular shape smaller than the liquid crystal cell. Further, the pixel portion 3 is along one side edge in the X direction as the width direction of the surface of the liquid crystal cell 2 and one end edge in the Y direction as the longitudinal direction of the liquid crystal cell 2.
[0017]
On the other side of the surface of the liquid crystal cell 2 along the X direction, an elongated flat plate X direction driver circuit 4 as a drive circuit is attached along the Y direction. The X direction driver circuit 4 drives each pixel of the pixel portion 3 of the liquid crystal cell 2 along the X direction. Further, an elongated flat plate-like Y direction driver circuit 5 as a drive circuit is attached to the other end along the Y direction on the surface of the liquid crystal cell 2. The Y direction driver circuit 5 drives each pixel of the pixel unit 3 of the liquid crystal cell 2 along the Y direction.
[0018]
On the other hand, the liquid crystal cell 2 includes an array substrate 11 having a substantially rectangular flat plate shape as shown in FIGS. The array substrate 11 includes a glass substrate 12 as a translucent substrate. The glass substrate 12 is a substantially transparent rectangular flat plate-shaped insulating substrate having a thickness of 70 μm or more and 100 μm or less. That is, the glass substrate 12 has such a thickness that light incident from the front surface side of the glass substrate 12 is sufficiently attenuated after multiple reflection in the glass substrate 12 and does not enter the optical sensor 21.
[0019]
Furthermore, a plurality of scanning lines 13 are arranged on the surface which is one main surface of the glass substrate 12 along the X direction which is the width direction of the glass substrate 12. Each of the scanning lines 13 is spaced at equal intervals in the Y direction, which is the longitudinal direction of the glass substrate 12. Further, on the surface of the glass substrate 12, a plurality of signal lines 14 are arranged along the Y direction of the glass substrate 12. Each of these signal lines 14 is spaced apart at equal intervals in the X direction of the glass substrate 12. Each of these signal lines 14 is arranged so as to intersect at right angles to each scanning line 13.
[0020]
A pixel electrode 15 is provided as a display electrode in a region on the glass substrate 12 surrounded by the scanning lines 13 and the signal lines 14. Further, a pixel TFT (Thin Film Transistor) 16 which is a thin film transistor as a switching element for pixel switching is provided at an intersection portion where these scanning lines 13 and signal lines 14 intersect. These pixel TFTs 16 are formed on the glass substrate 12 corresponding to the intersections of the scanning lines 13 and the signal lines 14. Further, the pixel TFTs 16 control the pixel electrodes 15 in a region surrounded by the scanning lines 13 and the signal lines 14 corresponding to the pixel TFTs 16. Specifically, these pixel TFTs 16 are controlled to be turned on / off by a scanning signal supplied from the scanning line 13, and the video data supplied to the signal line 14 is written to the pixel electrode 15 when turned on.
[0021]
Further, a plurality of auxiliary capacitance lines 17 are arranged on the surface of the glass substrate 12 along the X direction of the glass substrate 12. These auxiliary capacitance lines 17 are arranged in parallel to the scanning lines 13. The auxiliary capacitance line 17 is a metal for forming an auxiliary capacitance 18 formed between the auxiliary capacitance line 17 and the pixel TFT 16 adjacent to the auxiliary capacitance line 17. The auxiliary capacitor 18 is electrically connected to the pixel electrode 15. That is, the auxiliary capacitor 18 is formed between the auxiliary capacitor line 17 and the semiconductor layer 32 of the pixel TFT 16 by being supplied with a predetermined voltage from the auxiliary capacitor line 17.
[0022]
Further, in a region on the glass substrate 12 surrounded by the scanning lines 13 and the signal lines 14, an optical sensor 21 as a photoelectric conversion element and an electric signal conversion circuit 22 are provided. Here, the optical sensor 21 is for an optical input function that generates a photocurrent when receiving light. The electric signal conversion circuit 22 outputs the photocurrent generated by the optical sensor 21 to the signal line as an electric signal.
[0023]
The optical sensor 21 and the electrical signal conversion circuit 22 are electrically connected to the signal lines 14 surrounding the region where the optical sensor 21 and the electrical signal conversion circuit 22 are formed. Furthermore, the optical sensor 21 and the electric signal conversion circuit 22 each include a plurality of control lines 23 and power supply lines 24 arranged along the X direction of the glass substrate 12. Each of the control line 23 and the power supply line 24 is arranged in parallel to the scanning line 13.
[0024]
On the other hand, as shown in FIG. 1, an undercoat layer 31, which is a silicon oxide film, is laminated and formed on the glass substrate 12 of the array substrate 11. Further, the pixel TFT 16, the auxiliary capacitor 18, the P-type drive circuit TFT 26, the N-type drive circuit TFT 33, and the optical sensor 21 are formed on the undercoat layer 31. Each of the pixel TFT 16, the auxiliary capacitor 18, the P-type drive circuit TFT 26, the N-type drive circuit TFT 27, and the optical sensor 21 is provided in a state of being arranged in the same layer on the undercoat layer 31.
[0025]
Here, the pixel TFT 16 includes a semiconductor layer 32 formed by being stacked on the undercoat layer 31. On both sides of the semiconductor layer 32, LDD (Lightly Doped Drain) portions 33 and 34 are formed, respectively. These LDD portions 33 and 34 are connected to the semiconductor layer 32 and stacked on the undercoat layer 31. A source region 35 and a drain region 36 are formed on both sides of the LDD portions 33 and 34, respectively. The source region 35 and the drain region 36 are connected to the LDD portions 33 and 34 and stacked on the undercoat layer 31.
[0026]
Further, on the undercoat layer 31 including the semiconductor layer 32, the LDD portions 33 and 34, the source region 35, and the drain region 36, a gate insulating film 37 that is a silicon oxide film is laminated and formed. . On the gate insulating film 37, a gate electrode 38 is laminated. The gate electrode 38 is provided below the semiconductor layer 32 and has a width dimension equal to the width dimension of the semiconductor layer 32. An interlayer insulating film 39, which is a silicon oxide film, is laminated on the gate insulating film 37 including the gate electrode 38.
[0027]
Contact holes 41 and 42 communicating with the source region 35 and the drain region 36 are formed in the interlayer insulating film 39 and the gate insulating film 37. In these contact holes 41 and 42, a source electrode 43 and a drain electrode 44 are laminated. Here, the drain electrode 44 is electrically connected to the drain region 36 through the contact hole 42. The drain electrode 44 is electrically connected to the auxiliary capacitance line 17. Further, the source electrode 43 is electrically connected to the source region 35 through the contact hole 41. The source electrode 43 is electrically connected to the signal line 14.
[0028]
Further, on the interlayer insulating film 39 including the source electrode 43 and the drain electrode 44, a protective insulating film 45 that is a silicon nitride film is laminated and formed. The protective insulating film 45 covers the interlayer insulating film 39 including the source electrode 43 and the drain electrode 44. Further, a transparent organic insulating film 46 is laminated on the protective insulating film 45, and the protective organic film 45 is covered with the transparent organic insulating film 46. Further, an alignment film 47 is laminated on the transparent organic insulating film 46, and the transparent organic insulating film 46 is covered with the alignment film 47.
[0029]
Next, the auxiliary capacitor 18 includes a semiconductor layer 51 formed on the undercoat layer 31. A gate insulating film 37 is laminated on the semiconductor layer 51. A pair of auxiliary capacitance lines 17 is formed on the gate insulating film 37. These auxiliary capacitance lines 17 are located below the semiconductor layer 51 and form a capacitance with the semiconductor layer 51. The auxiliary capacitance lines 17 are arranged in a state of being spaced apart from each other in parallel.
[0030]
Further, an interlayer insulating film 39 is laminated on the gate insulating film 37 including these auxiliary capacitance lines 17. A contact hole 52 communicating with the semiconductor layer 51 of the auxiliary capacitor 18 is formed in the interlayer insulating film 39 and the gate insulating film 37. The contact hole 52 is provided between the pair of auxiliary capacitance lines 17. A drain electrode 44 is stacked in the contact hole 52. The drain electrode 44 is electrically connected to the semiconductor layer 51 through the contact hole 52.
[0031]
A contact hole 53 communicating with the drain electrode 44 is formed in the protective insulating film 45 and the transparent organic insulating film 46 formed on the interlayer insulating film 39 including the drain electrode 44. A pixel electrode 15 made of ITO (Indium Tin Oxide) is provided on the transparent organic insulating film 46 including the contact hole 53. The pixel electrode 15 is electrically connected to the drain electrode 44 through the contact hole 53. An alignment film 47 is laminated on the transparent organic insulating film 46 including the pixel electrode 15.
[0032]
Next, the P-type drive circuit TFT 26 includes a semiconductor layer 61 provided by being laminated on the undercoat layer 31. A drain region 62 and a source region 63 are provided on both sides of the semiconductor layer 61. The drain region 62 and the source region 63 are stacked on the undercoat layer 31 and are electrically connected to the semiconductor layer 61.
[0033]
A gate electrode 64 is stacked on the gate insulating film 37 stacked on the undercoat layer 31 including each of the semiconductor layer 61, the drain region 62, and the source region 63. The gate electrode 64 is located below the semiconductor layer 61 and has a width dimension equal to the width dimension of the semiconductor layer 61.
[0034]
Further, contact holes 65 and 66 communicating with the drain region 62 and the source region 63 are formed in the interlayer insulating film 38 and the gate insulating film 37 stacked on the gate insulating film 37 including the gate electrode 64. ing. In these contact holes 65 and 66, a drain electrode 67 and a source electrode 68 are laminated. Here, the drain electrode 67 is electrically connected to the drain region 62 through the contact hole 65. Further, the source electrode 68 is electrically connected to the source region 63 through the contact hole 66.
[0035]
Next, the N-type drive circuit TFT 27 includes a semiconductor layer 71 formed by being laminated on the undercoat layer 31. On both sides of the semiconductor layer 71, LDD portions 72 and 73 that are electrically connected to the semiconductor layer 71 and stacked on the undercoat layer 31 are formed. On both sides of the LDD portions 72 and 73, a drain region 74 and a source region 75, which are electrically connected to the LDD portions 72 and 73 and stacked on the undercoat layer 31, are formed.
[0036]
Further, a gate electrode 76 is stacked on the gate insulating film 37 stacked on the undercoat layer 31 including the semiconductor layer 71, the LDD portions 72 and 73, the drain region 74, and the source region 75. . The gate electrode 76 is located above the semiconductor layer 71 and has a width dimension equal to the width dimension of the semiconductor layer 71.
[0037]
Contact holes 77 and 78 communicating with the drain region 74 and the source region 75 are formed in the interlayer insulating film 39 and the gate insulating film 37 stacked on the gate insulating film 37 including the gate electrode 76. Yes. In these contact holes 77 and 78, a drain electrode 79 and a source electrode 80 are laminated. Here, the drain electrode 79 is electrically connected to the drain region 74 through the contact hole 77. Further, the source electrode 80 is electrically connected to the source region 75 through the contact hole 78. A protective insulating film 45 is laminated on the interlayer insulating film 39 including the drain electrode 79 and the source electrode 80.
[0038]
Next, the optical sensor 21 is a P-type P which is a low concentration impurity implantation region as a semiconductor layer laminated on the undercoat layer 31.⁻Region 81 and N-type N⁻An area 82 is provided. These P⁻Region 81 and N⁻The region 82 is a photoelectric conversion unit that is electrically connected to each other and generates a photocurrent by receiving light. These P⁻Region 81 and N⁻On both sides of region 82, these P⁻Region 81 and N⁻P-type P connected to the region 82 and stacked on the undercoat layer 31⁺Region 83 and N-type N⁺Region 84 is provided. Where this N⁺Region 84 is N⁻It is electrically connected to region 82. P⁺Region 83 is P⁻It is electrically connected to the region 81.
[0039]
And these P⁻Region 81, N⁻Region 82, P⁺Region 83 and N⁺A gate insulating film 37 is stacked on the undercoat layer 31 including each of the regions 84. In addition, P on the gate insulating film 37⁻On the region 81, a gate electrode 85 is stacked as an electrode portion that functions as an electrode. This gate electrode 85 is formed of P⁻The width dimension is equal to the width dimension of the region 81.
[0040]
Further, the interlayer insulating film 39 and the gate insulating film 37 stacked on the gate insulating film 37 including the gate electrode 85 include P⁺Region 83 and N⁺Contact holes 86 and 87 communicating with each of the regions 84 are formed. These contact holes 86 and 87 are formed by laminating a P-type region electrode 88 as an electrode portion functioning as an electrode and an N-type region electrode 89 as an electrode portion functioning as an electrode. Here, the P-type region electrode 88 is connected to P through the contact hole 86.⁺The region 83 is electrically connected. The P-type region electrode 88 protrudes toward the N-type region electrode 89 so as to cover the lower side of the gate electrode 85.
[0041]
Here, the N-type region electrode 89 is connected to N through the contact hole 87.⁺It is electrically connected to region 84. Further, the N-type region electrode 89 is formed of N⁻Projecting toward the P-type region electrode 88 side so as to cover the lower portion of the region 82. Further, the N-type region electrode 89 is formed of N⁻Region 82 and P⁻It protrudes toward the P-type region electrode 88 so as to cover part of the region 81. Therefore, the N-type region electrode 89 has N⁻It arrange | positions so that the light which injects from the surface side below the area | region 82 may be shielded.
[0042]
As a result, N of the optical sensor 21⁻Region 82 and P⁻The region 81 has these N⁻Region 82 and P⁻The surface side of the region 81 is covered with the gate electrode 85, the P-type region electrode 88 and the N-type region electrode 89 of the photosensor 21.
[0043]
On the other hand, an opposing substrate 91 having a rectangular flat plate shape is disposed facing the array substrate 11. The counter substrate 91 includes a glass substrate 92 as a translucent substrate. The glass substrate 92 is a substantially transparent rectangular flat plate-like insulating substrate having a thickness of about 70 μm. That is, the counter substrate 91 is disposed in a state where the surface side, which is one main surface of the glass substrate 92 of the counter substrate 91, is opposed in parallel to the surface side of the glass substrate 12 of the array substrate 11.
[0044]
Further, on the surface of the glass substrate 92 of the counter substrate 91, each of the color filters 93 as the three colored layers of red, green, and blue in which pigments are dispersed is laminated in a stripe shape. . On the surface of these color filters 93, a counter electrode 94 made of ITO (Indium Tin Oxide) is laminated and formed. On the counter electrode 94, an alignment film 95 covering the counter electrode 94 is laminated. Between the alignment film 95 of the counter substrate 91 and the alignment film 47 of the array substrate 11, the alignment film 95 of the counter substrate 91 and the alignment film 47 of the array substrate 11 are opposed in parallel to form a cell. Later, a liquid crystal 96 is injected and inserted to be sealed.
[0045]
Also, a rectangular flat plate-like backlight 98 is disposed on the back side of the counter substrate. The backlight 98 is installed in parallel to the back surface of the counter substrate 91, and to the detection object S as a subject located on the back surface side of the array substrate 11 through the counter substrate 91 and the array substrate 11. And light.
[0046]
Next, a method for manufacturing the liquid crystal display device according to the first embodiment will be described.
[0047]
First, on the surface of a glass substrate 12 having a thickness of about 700 μm, an undercoat layer 31 of a silicon oxide film and an amorphous semiconductor film (not shown) as an amorphous semiconductor film serving as an active layer are formed by plasma CVD (Chemical Vapor Deposition). A silicon film is formed to a thickness of about 50 nm.
[0048]
At this time, B by ion doping method₂H₆/ H₂Is the source gas, the acceleration voltage is 10 KeV, and the dose is 4 × 10¹¹atoms / cm²As a result, boron (B) is implanted at a low concentration into the amorphous silicon film.
[0049]
Next, the amorphous silicon film is polycrystallized by excimer laser annealing (ELA) to form a polysilicon film (not shown) as a polycrystalline semiconductor film.
[0050]
Thereafter, the polysilicon film is etched into an island shape by a photolithography process, and semiconductor layers 32 and 51 constituting the pixel TFT 16, the P-type drive circuit TFT 26, the N-type drive circuit TFT 27, the photosensor 21, and the auxiliary capacitor 18. , 61, 71, P⁻Region 81 and N⁻Each of the regions 82 is formed.
[0051]
Furthermore, these semiconductor layers 32, 51, 61, 71, P⁻Region 81 and N⁻A silicon oxide gate insulating film 37 is formed to a thickness of about 80 nm on the entire surface of the undercoat layer 31 including each of the regions 82 by plasma CVD.
[0052]
Next, after forming a resist film on the gate insulating film 37, the resist film is patterned into a predetermined shape.
[0053]
Thereafter, using this resist film as a mask, the semiconductor layer 51 of the auxiliary capacitor 18, the source region 35 and the drain region 36 of the pixel TFT 16, the drain region 74 and the source region 75 of the N-type drive circuit TFT 27, and the N of the optical sensor 21.⁺Each of the regions 84 is subjected to PH by ion doping.₃/ H₂Is the source gas, the acceleration voltage is 50 KeV, and the dose is 2 × 10^{1 5}atoms / cm²As a result, phosphorus (P) is implanted at a high concentration.
[0054]
Thereafter, after the resist film on the gate insulating film 37 is removed, an electrode film (not shown) as a molybdenum-tungsten (MoW) alloy film is deposited on the entire surface of the gate insulating film 37 by sputtering to a thickness of about 300 nm. To do.
[0055]
Further, the electrode films of the P-type drive circuit TFT 26 and the optical sensor 21 are patterned into a predetermined shape by a photolithography process.
[0056]
Thereafter, using this electrode film as a mask, B is formed by ion doping.₂H₆/ H₂Is the source gas, the acceleration voltage is 44 KeV, and the dose is 1 × 10^{1 5}atoms / cm²As a result, boron (B) is implanted at a high concentration so that the source region 63 and the drain region 62 of the P-type drive circuit TFT 26 and the P of the optical sensor 21⁺Each of the regions 83 is formed.
[0057]
Further, the electrode films of the pixel TFT 16, the N-type drive circuit TFT 27, the photosensor 21, and the auxiliary capacitor 18 are patterned into predetermined shapes, and the gate electrode 38 of the pixel TFT 16, the gate electrode 76 of the N-type drive circuit TFT 27, and the light Each of the gate electrode 85 and the auxiliary capacitance line 17 of the sensor 21 is formed.
[0058]
Thereafter, using the gate electrodes 38, 76, and 85 of the pixel TFT 16, the N-type drive circuit TFT 27, and the optical sensor 21 as a mask, PH is performed by ion doping.₃/ H₂Is the source gas, the acceleration voltage is 50 KeV, and the dose is 4 × 10^{1 3}atoms / cm²As a result, phosphorus (P) is injected at a low concentration, and the LDD portions 33, 34, 72, 73 of the pixel TFT 16 and the N-type drive circuit TFT 27 and the N of the optical sensor 21⁻Each of the regions 82 is formed.
[0059]
At this time, the gate electrode 85 of the photosensor 21 causes the P of the photosensor 21 to⁻The region 81 has a structure that blocks light from below.
[0060]
Further, the LDD portions 33, 34, 72, 73 of the pixel TFT 16 and the N-type drive circuit TFT 27 and the N of the optical sensor 21⁻Each of the regions 82 is annealed at a temperature of 600 ° C. for about 1 hour, and these LDD portions 33, 34, 72, 73 and N⁻The impurity implanted in the region 82 is activated.
[0061]
Next, an interlayer insulating film of a silicon oxide film is formed on the entire surface of the gate insulating film 37 including the pixel TFT 16, the auxiliary capacitor 18, the P-type driving circuit TFT 26, the N-type driving circuit TFT 27 and the optical sensor 21 by a plasma CVD method. 39 is deposited to about 660 nm.
[0062]
Thereafter, contact holes 41 and 42 communicating with the source region 35 and the drain region 36 of the pixel TFT 16 and the drain region 62 and the source region 63 of the P-type drive circuit TFT 26 are connected to the interlayer insulating film 39 and the gate insulating film 37, respectively. Contact holes 65 and 66 communicating with the drain region 74, contact holes 77 and 78 communicating with the drain region 74 and the source region 75 of the N-type drive circuit TFT 27, and P of the optical sensor 21.⁺Region 83 and N⁺Contact holes 86 and 87 communicating with the region 84 are formed by photoetching.
[0063]
Further, a molybdenum (Mo) film is deposited on the surface of the interlayer insulating film 39 by a sputtering method to a thickness of about 15 nm, an aluminum-neodymium (AlNd) film is then deposited to a thickness of about 600 nm, and a molybdenum (Mo) film is further deposited to a thickness of about 50 nm. A wiring film (not shown) as a metal alloy film is formed by deposition.
[0064]
Thereafter, the wiring film is patterned into a predetermined shape by a photoetching method to form the signal line 14 and the signal line 14 is electrically connected to the drain region 36 of the pixel TFT 16.
[0065]
At the same time, the source region 35 of the pixel TFT 16 is electrically connected to the auxiliary capacitance line 17 and various wirings such as the P-type region electrode 88 and the N-type region electrode 89 in the optical sensor 21 and the electric signal conversion circuit 22 are electrically connected. Further, various wirings such as drain regions 62 and 74 and source regions 63 and 75 in the P-type drive circuit TFT 26 and the N-type drive circuit TFT 27 are electrically connected.
[0066]
At this time, N of the optical sensor 21⁺An N-type region electrode 89 electrically connected to the region 84 is connected to the N of the optical sensor 21.⁻Light incident from the surface side below the region 82 is shielded.
[0067]
Further, the pixel TFT 16, the P-type drive circuit TFT 26 and the N-type drive circuit TFT 27 include drain electrodes 44, 67, 79 and source electrodes 43, 68, 80, and a P-type region electrode 88 and an N-type region electrode 89 of the photosensor 21. A protective insulating film 45 made of a silicon nitride film is formed on the entire surface of the interlayer insulating film 39 by a plasma CVD method, and then a contact hole 53 communicating with the drain electrode 44 of the pixel TFT 16 is formed by a photoetching method. A film 45 is formed.
[0068]
Next, a transparent organic insulating film 46 is applied on the entire surface of the protective insulating film 45 to form a film having a thickness of about 2 μm, and a contact hole 53 communicating with the drain electrode 44 of the pixel TFT 16 is formed in the transparent organic insulating film 46 again. Form.
[0069]
Thereafter, an ITO (Indium Tin Oxide) film having a thickness of about 100 nm is formed on the surface of the transparent organic insulating film 46 including the contact hole 53 by a sputtering method, and then patterned into a predetermined shape by a photoetching method to form a pixel electrode. 15 is formed.
[0070]
Further, a low temperature cure type polyimide is printed and applied on the entire surface of the transparent organic insulating film 46 including the pixel electrode 15, and then an alignment film 47 is formed by rubbing to form the array substrate 11.
[0071]
On the other hand, the counter substrate 91 is formed with stripes of the three color filters 93 of red, green, and blue in which pigments are dispersed on the entire surface of the glass substrate 92 of the counter substrate 91.
[0072]
Thereafter, a counter electrode 94 is formed on the entire surface of the color filter 93 by depositing about 100 nm of ITO (Indium Tin Oxide) by sputtering.
[0073]
Further, polyimide is printed on the entire surface of the counter electrode 94 and then rubbed to form an alignment film 95 to form the counter substrate 91.
[0074]
Next, a cell is formed by making the alignment film 47 side of the array substrate 11 face the alignment film 95 side of the counter substrate 91. Thereafter, a liquid crystal 96 is injected between the alignment film 47 of the array substrate 11 and the alignment film 95 of the counter substrate 91 and sealed.
[0075]
Thereafter, the back surface of the glass substrate 12 of the array substrate 11 is polished so that the thickness of the glass substrate 12 is 70 μm or more and 100 μm.
[0076]
Then, a deflection plate (not shown) is attached to the back side of each of the array substrate 11 and the counter substrate 91 to obtain the liquid crystal display device 1 with an input function.
[0077]
As described above, according to the first embodiment, when the dependence of the thickness of the glass substrate 12 on the light detection sensitivity of the optical sensor 21 of the array substrate 11 is evaluated, as shown in FIG. The light detection sensitivity of the sensor 21 was improved as the glass substrate 12 of the array substrate 11 became thinner. In particular, the index of the light detection sensitivity of the optical sensor 21 is used as the ratio of the photocurrent when the detection object S is white paper to the photocurrent when the detection object S is black paper, and the contrast of the reflectance of the paper used. When the ratio was 15, when the thickness of the glass substrate 12 was 100 μm, the light detection sensitivity of the optical sensor 21 was 15 which was the contrast ratio, and became saturated.
[0078]
On the other hand, the mechanical strength limit when the thickness of the glass substrate 12 is thinned by polishing such as mechanical polishing or chemical polishing is 70 μm. Therefore, in order to maximize the light detection sensitivity of the optical sensor 21, the thickness of the glass substrate 12 may be set to 70 μm or more and 100 μm.
[0079]
That is, by setting the thickness of the glass substrate 12 to 70 μm or more and 100 μm or less, light from the backlight 98 disposed on the back surface side of the counter substrate, which is the front surface side of the glass substrate 12, is reflected on the glass substrate 12. When the light is incident from the surface side, multiple reflections are repeated inside the glass substrate 12 and sufficiently attenuated. As a result, it is possible to reliably prevent stray light from entering the optical sensor 21 due to multiple reflection of light incident from the surface side by the glass substrate 12 with a simple configuration.
[0080]
Therefore, since the light incident on the optical sensor 21 can be limited only to the light incident from the back side of the glass substrate 12, only the light reflected by the detection object S facing the back side of the glass substrate 12 can be used as the optical sensor 21. Is detected. As a result, generation of an extra photocurrent of the photosensor 21 due to light incident from the back side of the glass substrate 12 can be prevented, so that the photodetection sensitivity of the photosensor 21 can be improved. The detection sensitivity can be improved. Therefore, the liquid crystal display device 1 with a highly sensitive input function can be manufactured.
[0081]
In addition, P of this optical sensor 21⁻Region 81 and N⁻Each surface side of the region 82 was covered with the gate electrode 85, the P-type region electrode 88 and the N-type region electrode 89 of the photosensor 21. As a result, P of the optical sensor 21 for the light emitted from the backlight 98 is displayed.⁻Region 81 and N⁻Incidence to the region 82 can be reliably prevented by the gate electrode 85, the P-type region electrode 88 and the N-type region electrode 89 of the photosensor 21. For this reason, since generation | occurrence | production of the excess photocurrent of this photosensor 21 can be prevented, the photodetection sensitivity by this photosensor 21 can be improved more.
[0082]
According to the first embodiment, the P of the optical sensor 21⁻Region 81 and N⁻Each surface side of the region 82 is covered with the gate electrode 85, the P-type region electrode 88 and the N-type region electrode 89 of the photosensor 21. P of the optical sensor 21 by at least one of⁻Region 81 and N⁻It is only necessary that each surface side of the region 82 is covered.
[0083]
Further, the thickness of the glass substrate 12 of the array substrate 11 is controlled to prevent multiple reflection of light incident from the surface side of the glass substrate 12, but the material of the glass substrate 12 is changed. The refractive index of light by the glass substrate 12 is controlled, or an antireflection film 99 as a sheet-like film body is attached to the back surface of the glass substrate 12 as in the second embodiment shown in FIG. And even if it is the structure which prevents the multiple reflection of the light which injects from the surface side of this glass substrate 12, there can exist an effect similar to the said 1st Embodiment.
[0084]
Furthermore, although the liquid crystal display device 1 in which the liquid crystal 96 is interposed between the array substrate 11 and the counter substrate 91 has been described, a flat display device other than the liquid crystal display device 1 can be used correspondingly.
[0085]
【The invention's effect】
According to the present invention, the translucent substrate has a thickness that prevents the light entering from one main surface side of the translucent substrate from being incident on the photoelectric conversion element due to multiple reflection of light. As a result, it is possible to prevent generation of an extra photocurrent of the photoelectric conversion element due to light incident from the one main surface side of the translucent substrate, and thus it is possible to improve the light detection sensitivity of the photoelectric conversion element.
[0086]
In addition, the film body attached to the light-transmitting substrate can prevent light incident from one main surface side of the light-transmitting substrate from entering the photoelectric conversion element due to multiple reflection. For this reason, since generation | occurrence | production of the excess photocurrent of the photoelectric conversion element by the light which injects from the one main surface side of this translucent board | substrate can be prevented, the photodetection sensitivity by this photoelectric conversion element can be improved.
[0087]
Further, the light-transmitting substrate has a refractive index that prevents the light incident from one main surface side of the light-transmitting substrate from entering the photoelectric conversion element due to multiple reflection. As a result, it is possible to prevent generation of an extra photocurrent of the photoelectric conversion element due to light incident from the one main surface side of the translucent substrate, and thus it is possible to improve the light detection sensitivity of the photoelectric conversion element.
[Brief description of the drawings]
FIG. 1 is an explanatory cross-sectional view showing a first embodiment of a flat display device of the present invention.
FIG. 2 is an explanatory plan view showing the flat display device.
FIG. 3 is an explanatory plan view showing a part of the flat display device.
FIG. 4 is a secondary graph showing the relationship between the thickness of the translucent substrate of the flat display device and the light detection sensitivity of the photoelectric conversion element.
FIG. 5 is an explanatory sectional view showing a flat display device according to a second embodiment of the present invention.
[Explanation of symbols]
1. Liquid crystal display device as a flat display device
12 Glass substrate as translucent substrate
15 Pixel electrode
16 Pixel TFT as switching element
21 Optical sensor as a photoelectric conversion element
81 P as a semiconductor layer⁻region
82 N as semiconductor layer⁻region
85 Gate electrode as electrode part
88 P-type region electrode as electrode part
89 N-type region electrode as electrode part

Claims (5)

A translucent substrate, a switching element and a photoelectric conversion element provided on one main surface of the translucent substrate, and a pixel electrode provided on one main surface of the translucent substrate and controlled by the switching element Equipped,
The flat display device, wherein the translucent substrate has a thickness that prevents the light entering from one main surface side of the translucent substrate from being incident on the photoelectric conversion element due to multiple reflection of light. . The flat display device according to claim 1, wherein a thickness of the translucent substrate is 70 μm or more and 100 μm or less. A translucent substrate, a switching element and a photoelectric conversion element provided on one main surface of the translucent substrate, a pixel electrode provided on one main surface of the translucent substrate and controlled by the switching element;
A flat display device comprising: a film body attached to the translucent substrate and preventing incidence to the photoelectric conversion element due to multiple reflection of light incident from one main surface side of the translucent substrate. . A translucent substrate, a switching element and a photoelectric conversion element provided on one main surface of the translucent substrate, and a pixel electrode provided on one main surface of the translucent substrate and controlled by the switching element Equipped,
2. The flat display device according to claim 1, wherein the translucent substrate has a refractive index that prevents the light incident from one main surface side of the translucent substrate from entering the photoelectric conversion element due to multiple reflection. The photoelectric conversion element includes a semiconductor layer that generates a photocurrent by receiving light, and an electrode portion that serves as an electrode of the semiconductor layer.
The flat display device according to claim 1, wherein one main surface side of the semiconductor layer is covered with the electrode portion.

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