JP2007102069A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device which has high transmissivity and a high product yield. <P>SOLUTION: The liquid crystal display device has: an array substrate 1 which has a substrate, a plurality of switching elements formed on the substrate, an interlayer insulating film 19 formed on those switching elements, and a plurality of pixel electrodes 27 formed on the interlayer insulating film; a counter substrate 2 arranged opposite the array substrate across a gap; and a liquid crystal layer 3 sandwiched between the array substrate and counter substrate. The interlayer insulating film 19 is formed to such a film thickness that the transmissivity of the array substrate 1 exceeds 97% by laminating a first interlayer insulating film 20 formed of SiN<SB>X</SB>to a 50 to 1,000 nm film thickness and a second interlayer insulating film 21 formed of SiO<SB>X</SB>to a 50 to 1,000 nm film thickness. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device, and more particularly to a transmissive liquid crystal display device.

  In recent years, liquid crystal display devices have features such as light weight, thinness, and low power consumption, and thus have been applied to various fields such as PC (personal computer) monitors and televisions. In general, a liquid crystal display device includes an array substrate on which TFTs (thin film transistors) are formed, a counter substrate disposed opposite to the array substrate with a gap, a liquid crystal layer sandwiched between the two substrates, an array substrate or And a color filter provided on the counter substrate. In addition, the liquid crystal display device includes, for example, a battery and a backlight unit.

The transmittance of the liquid crystal display device is substantially determined by the various insulating films, color filters, and pixel electrodes that form the array substrate, and the counter electrode that forms the counter substrate. For example, in the case of a top-gate TFT, the gate insulating film and the interlayer insulating film on the gate electrode are formed by laminating a silicon nitride film and a silicon oxide film (see, for example, Patent Document 1). The interlayer insulating film is formed using PEP (Photo Engraving Process). However, since the interlayer insulating film has a two-layer structure, the number of PEPs can be reduced compared to the case of a three-layer structure, and the manufacturing time can be shortened. Can be measured.
JP 2003-338509 A

However, when the interlayer insulating film is simply formed with a two-layer structure as described above, the transmittance of the liquid crystal display device is lowered. In addition, the interlayer insulating film plays an important role from the viewpoint of product reliability.
The present invention has been made in view of the above points, and an object thereof is to provide a liquid crystal display device having high transmittance and high product yield.

In order to solve the above-described problem, a liquid crystal display device according to an aspect of the present invention includes:
An array substrate having a substrate, a plurality of switching elements formed on the substrate, an interlayer insulating film formed on the switching elements, and a plurality of pixel electrodes formed on the interlayer insulating film; ,
A counter substrate disposed opposite to the array substrate with a gap;
A liquid crystal layer sandwiched between the array substrate and the counter substrate,
The interlayer insulating film includes a first interlayer insulating film formed from SiN _{X to} a thickness of 50 nm to 1000 nm, and a second interlayer insulating film formed from SiO _X material to a thickness of 50 nm to 1000 nm. The array substrate is formed so that the transmittance of the array substrate exceeds 97%.

  According to the present invention, it is possible to provide a liquid crystal display device having a high transmittance and a high product yield.

Hereinafter, a liquid crystal display device according to an embodiment of the present invention will be described in detail with reference to the drawings.
As shown in FIGS. 1, 2, and 3, the liquid crystal display device includes an array substrate 1, a counter substrate 2, a liquid crystal layer 3, a color filter 4, a first polarizing plate 5 as an optical unit, and a second polarizing plate. A polarizing plate 6 and a backlight unit 7 are provided.

The array substrate 1 includes a glass substrate 10 as a transparent insulating substrate. An undercoat insulating film 11 is formed on the glass substrate 10. The undercoat insulating film 11 is formed by laminating a first undercoat insulating film 12 and a second undercoat insulating film 13. The first undercoat insulating film 12 and the second undercoat insulating film 13 are sequentially formed on the glass substrate 10. In this embodiment, the first undercoat insulating film 12 is formed with a SiN _X material to a thickness of 20 nm, and the second undercoat insulating film 13 is formed with a SiO _X material to a thickness of 100 nm.

  On the undercoat insulating film 11, a plurality of stripe-shaped signal lines 22 and a plurality of stripe-shaped scanning lines 23 are formed in a lattice pattern so as to intersect each other. A plurality of stripe-shaped auxiliary capacitance lines 24 are formed on the undercoat insulating film 11 and extend in parallel with the scanning lines 23. Each auxiliary capacitance line 24 forms an auxiliary capacitance element 30. Pixel portions 8 are formed in regions surrounded by two adjacent signal lines 22 and two adjacent auxiliary capacitance lines 24, respectively. The pixel unit 8 is provided between the array substrate 1 and the counter substrate 2.

A TFT () 14 as a switching element is provided in the vicinity of each intersection of the signal line 22 and the scanning line 23. The TFT 14 includes, as a channel layer, for example, a channel layer 15 made of amorphous silicon (a-Si) or polysilicon (p-Si), a gate insulating film 17, and a gate electrode 18 extending from a part of the scanning line 23. Have. In this embodiment, the channel layer 15 is made of p-Si material to a thickness of 49 nm, and the gate insulating film 17 is made of SiO _x material to a thickness of 105 nm. Further, the gate electrode 18 and the scanning line 23 are formed with a thickness of 250 nm, for example, from a material of MoW.

  More specifically, a channel layer 15 and an auxiliary capacitance electrode 16 are formed on the undercoat insulating film 11, and a gate insulating film 17 is formed on the undercoat insulating film including the channel layer and the auxiliary capacitance electrode. ing. On the gate insulating film 17, the scanning line 23, the gate electrode 18, and the auxiliary capacitance line 24 are disposed. The auxiliary capacitance electrode 16 and the auxiliary capacitance line 24 are arranged to face each other with the gate insulating film 17 interposed therebetween. An interlayer insulating film 19 is formed on the gate insulating film 17 including the scanning line 23, the gate electrode 18, and the auxiliary capacitance line 24.

The interlayer insulating film 19 is formed by laminating a first interlayer insulating film 20 and a second interlayer insulating film 21 that function as a passivation film. The first interlayer insulating film 20 and the second interlayer insulating film 21 are sequentially formed on the gate insulating film 17. In this embodiment, the first interlayer insulating film 20 is formed with a film thickness of 275 nm using a SiN _X material, and the second interlayer insulating film 21 is formed with a film thickness of 170 nm using a SiO _X material.

  On the interlayer insulating film 19, a signal line 22 and a contact wiring 25 are formed of a conductive material such as MAM. Here, MAM is an abbreviation of Mo (molybdenum) /Al.Nd (aluminum-neodymium alloy) / Mo (molybdenum) and is a metal film having a three-layer structure. The signal line 22 is connected to the source region RS of the channel layer 15 through a contact hole formed in the gate insulating film 17 and the interlayer insulating film 19. The contact wiring 25 is connected to the drain region RD of the channel layer 15 through a contact hole formed in the gate insulating film 17 and the interlayer insulating film 19. The contact wiring 25 is connected to the auxiliary capacitance electrode 16 through another contact hole formed in the gate insulating film 17 and the interlayer insulating film 19. Here, the auxiliary capacitance line 24 is formed except for the connection portion between the auxiliary capacitance electrode 16 and the contact wiring 25.

  On the TFT 14, the signal line 22, the contact wiring 25, and the interlayer insulating film 19, a red colored layer 4R, a green colored layer 4G, and a blue colored layer 4B are adjacent to each other and arranged alternately. The peripheral portions of the colored layers 4R, 4G, and 4B overlap the signal line 22. The colored layers 4R, 4G, and 4B form the color filter 4. On the interlayer insulating film 19, a frame portion (not shown) is formed along the peripheral edge portion of the color filter 4. The frame portion contributes to shielding light leaking from the peripheral edge of the color filter 4.

  On the colored layers 4R, 4G, and 4B, a plurality of pixel electrodes 27 are provided in a matrix by a transparent conductive material such as ITO (indium tin oxide). Here, the pixel portion 8 is formed by the TFT 14, the auxiliary capacitance element 30, the pixel electrode 27, and the like.

  The pixel electrode 27 is connected to the contact wiring 25 through a contact hole formed in the colored layer. The peripheral edge of the pixel electrode 27 overlaps the signal line 22 and the auxiliary capacitance line 24. For this reason, the signal line 22 and the auxiliary capacitance line 24 have a light shielding function as a black matrix.

  A plurality of columnar spacers 28 are formed on the pixel electrode 27. The columnar spacers 28 are not limited to the array substrate 1 and may be formed on the counter substrate 2. An alignment film 29 is formed on the color filter 4 and the pixel electrode 27.

  The counter substrate 2 includes a glass substrate 40 as a transparent insulating substrate. On the glass substrate 40, a common electrode 41 is formed of a transparent conductive material such as ITO. An alignment film 42 is formed on the common electrode 41.

  The array substrate 1 and the counter substrate 2 are bonded to each other by, for example, a thermosetting sealing material 51 disposed at the peripheral edge of both substrates, and are arranged to face each other while holding a predetermined gap by a plurality of columnar spacers 28. Yes. A liquid crystal layer 3 is formed in a region surrounded by the array substrate 1, the counter substrate 2, and the sealing material 51. A liquid crystal injection port 52 is provided in a part of the sealing material 51, and the liquid crystal injection port is sealed with a sealing material 53.

  A first polarizing plate 5 is disposed on the outer surface of the array substrate 1. A second polarizing plate 6 is disposed on the outer surface of the counter substrate 2. The liquid crystal display device is also provided with a backlight unit 7 and a bezel (not shown). The backlight unit 7 includes a light guide plate 7a, and a light source and a reflection plate (not shown) disposed to face one side edge of the light guide plate. The light guide plate 7 a is disposed opposite to the first polarizing plate 5.

Next, a detailed configuration of the above-described liquid crystal display device will be described together with a manufacturing method.
First, the glass substrate 10 is prepared. On the prepared glass substrate 10, by CVD (Chemical Vapor Deposition) method, a first undercoat insulating film 12 made of SiN _{X having a} thickness of 20 nm, a second undercoat insulating film 13 made of SiO _{X having a} thickness of 100 nm, and A 49 nm-thickness semiconductor film made of a-Si is sequentially formed. The formed semiconductor film is polycrystallized by excimer laser annealing (ELA) and further patterned by PEP (Photo Engraving Process). As a result, the channel layer 15 and the auxiliary capacitance electrode 16 made of p-Si are formed.

Subsequently, undercoat insulating film 11, on the channel layer 15 and the storage capacitor electrode 16, TEOS (Tetra Ethyl Ortho Silicate ) consisting SiO _X by the plasma CVD method using a raw material the thickness 135nm of the gate insulating film 17 is deposited Is done. Note that the gate insulating film may be formed to a thickness of about 80 nm to 195 nm.

  After the gate insulating film 17 is formed, a conductive film made of MoW is formed on the gate insulating film, and further patterned by PEP to form a gate electrode 18 made of MoW having a thickness of 250 nm, the scanning line 23, and the auxiliary capacitance line. 24 is formed. At this time, the gate insulating film 17 is also slightly cut, and the thickness of the gate insulating film (residual film) becomes 105 nm. Next, an impurity is implanted into the channel layer 15 by ion doping using the gate electrode 18 as a mask to form the source region RS and the drain region RD in the channel layer.

Subsequently, a 275 nm-thick first interlayer insulating film 20 made of SiN _{X is} formed on the gate insulating film 17, the gate electrode 18, the scanning line 23, and the auxiliary capacitance line 24 by a CVD method. Then, on the first interlayer insulating film 20, forming the second interlayer insulating film 21 of thickness 170nm made of SiO _X by a CVD method. Thereby, an interlayer insulating film 19 is formed.

  Next, a plurality of portions of the gate insulating film 17 and the interlayer insulating film 19 are etched by a normal manufacturing process, such as repeating film formation and PEP, and are respectively formed on the source region RS and drain region RD of the channel layer 15 and the auxiliary capacitance electrode 16. A contact hole is formed. After the contact hole is formed, the signal line 22 and the contact wiring 25 made of MAM are formed.

  Subsequently, the colored layers 4R, 4G, and the like are formed on the interlayer insulating film 19, the signal line 22, and the contact wiring 25 by a normal manufacturing process such as application of a colored resist (red resist, green resist, blue resist) and repeated photoetching. 4B are formed adjacent to each other in order, and a contact hole is formed in each colored layer. Thereby, the color filter 4 is formed.

  After that, for example, ITO is deposited on the color filter 4 including the contact holes formed in the colored layers 4R, 4G, and 4B by a sputtering method. Next, the deposited ITO film is patterned by PEP using a predetermined mask. Thereby, a plurality of pixel electrodes 27 are formed on the colored layers 4R, 4G, and 4B. Subsequently, after forming a plurality of columnar spacers 28 on the pixel electrode 27, an alignment film 29 is formed on the entire surface of the glass substrate 10. Thereby, the array substrate 1 is completed.

  On the other hand, in the counter substrate 2, first, a glass substrate 40 is prepared. An ITO film is formed on the prepared glass substrate 40 to form a common electrode 41. Subsequently, an alignment film 42 is formed on the entire surface of the glass substrate 40 including the common electrode 41. Thereby, the counter substrate 2 is completed.

  Next, a sealing material 51 is formed along the periphery of the alignment film 42 of the counter substrate 2. Subsequently, the array substrate 1 and the counter substrate 2 are arranged opposite to each other while holding a predetermined gap by a plurality of columnar spacers 28, and the peripheral portions of the array substrate and the counter substrate are bonded to each other by a seal material 51. Thereafter, liquid crystal is injected from a liquid crystal injection port 52 formed in a part of the sealing material 51. Next, the liquid crystal injection port 52 is sealed with a sealing material 53. As a result, the liquid crystal is sealed between the array substrate 1 and the counter substrate 2 to form the liquid crystal layer 3.

  Next, the first polarizing plate 5 is disposed on the outer surface of the array substrate 1, the second polarizing plate 6 is disposed on the outer surface of the counter substrate 2, and a backlight unit 7 and a bezel (not shown) are attached to assemble the module. Thereby, a liquid crystal display device is completed.

  Here, the inventor of the present application investigated the transmittance of the array substrate 1. At that time, as shown in FIG. 4, unlike the above-described embodiment, the array substrate 1 was formed without providing the colored layers 4R, 4G, and 4B, the pixel electrode 27, and the alignment film 29. Further, the array substrate 1 was formed with the interlayer insulating film 19 composed of two layers of the first interlayer insulating film 20 and the second interlayer insulating film 21 without providing the passivation film as in the above-described embodiment. The film thicknesses of the first interlayer insulating film 20 and the second interlayer insulating film 21 were changed in the range of 50 nm to 1000 nm, respectively.

  As shown in FIGS. 5, 6, and 7, the transmittance of the array substrate 1 when the film thicknesses of the first interlayer insulating film 20 and the second interlayer insulating film 21 are changed is known. If the transmittance is 97% or more, it can be determined that the transmittance is high. Examples of the range of the first interlayer insulating film 20 and the second interlayer insulating film 21 whose transmittance is approximately 97% or more include the following (1) to (8).

(1) First interlayer insulating film: 125 nm to 175 nm
Second interlayer insulating film: 50 nm to 1000 nm
(2) First interlayer insulating film: 250 nm to 300 nm
Second interlayer insulating film: 50 nm to 1000 nm
(3) First interlayer insulating film: 400 nm to 450 nm
Second interlayer insulating film: 500 nm to 1000 nm
(4) First interlayer insulating film: 550 nm to 600 nm
Second interlayer insulating film: 500 nm to 1000 nm
(5) First interlayer insulating film: 50 nm to 1000 nm
Second interlayer insulating film: 150 nm to 200 nm
(6) First interlayer insulating film: 50 nm to 1000 nm
Second interlayer insulating film: 350 nm to 400 nm
(7) First interlayer insulating film: 100 nm to 1000 nm
Second interlayer insulating film: 500 nm to 600 nm
(8) First interlayer insulating film: 100 nm to 1000 nm
Second interlayer insulating film: 700 nm to 750 nm
In particular, 10 points P1 to P10 shown in FIG. 5 are particularly excellent in transmittance. The liquid crystal display device of the above-described embodiment has excellent transmittance because the film thickness of the first interlayer insulating film 20 is 275 nm and the film thickness of the second interlayer insulating film 21 is 170 nm (P7). It has a configuration.

  Next, the reason why the transmittance of the liquid crystal display device of the above-described embodiment is high will be further described. As shown in FIG. 8, the liquid crystal display device includes a high refractive index layer (first undercoat insulating film 12, first interlayer) in a low refractive index layer (second undercoat insulating film 13, gate insulating film 17, etc.). Since the insulating film 20) is sandwiched, interface reflection occurs.

  Here, the first undercoat insulating film 12 is taken as an example of the high refractive index layer, and the interface reflection is described by assuming that the refractive index of the first undercoat insulating film is n and the film thickness thereof is d as shown in FIG. . Then, the optical path difference between the transmitted light L1 transmitted through the first undercoat insulating film and emitted from the first undercoat insulating film and the transmitted light L2 emitted from the first undercoat insulating film due to interface reflection is 2nd. When the wavelengths of the transmitted light L1 and the transmitted light L2 are λ, the phase difference between the transmitted light L1 and the transmitted light L2 is (2π / λ) × 2nd. When the film thickness d decreases, the phase difference between the transmitted light L1 and the transmitted light L2 approaches 0, so that the transmitted light L1 and the transmitted light L2 interfere with each other and strengthen each other.

  In this embodiment, the film thickness of the first undercoat insulating film 12 is 20 nm, the film thickness of the first interlayer insulating film 20 is 275 nm, and the film thickness of the high refractive index layer is small. As described above, although the liquid crystal display device is formed by sandwiching the high refractive index layer in the low refractive index layer, the film thickness of the high refractive index layer is small, so that the transmittance can be increased.

Here, the inventor of the present application further investigated the transmittance of the liquid crystal display device described above. At this time, as shown in FIG. 10, unlike the above-described embodiment, the film thickness of the second undercoat insulating film 13 was set to 500 nm, and the interlayer insulating film 19 was formed to a film thickness of 350 nm from a SiO _x material. On the interlayer insulating film 19, a passivation film having a thickness of 450 nm was formed using a SiN _X material. The thickness (film thickness) of the pixel electrode 27 was 50 nm. The film thickness of the conventional first undercoat insulating film 11 is 50 nm, but during the investigation, the film thickness of the first undercoat insulating film was changed in the range of 0 nm to 50 nm.

  As shown in FIG. 11, the transmittance of the liquid crystal display device when the film thickness of the first undercoat insulating film 11 is changed can be seen, and it can be seen that the thinner the film thickness, the higher the transmittance. Further, it was found that the transmittance of the liquid crystal display device formed with the first undercoat insulating film 11 having a film thickness of 20 nm was 3.2% higher on average than when formed with a film thickness of 50 nm.

According to the liquid crystal display device configured as described above, the interlayer insulating film 19 is formed of the first interlayer insulating film 20 formed of a SiN _X material to a thickness of 275 nm and the SiO _X material of a thickness of 170 nm. Two layers with the formed second interlayer insulating film 21 are laminated. Thereby, since the transmittance of the array substrate 1 exceeds 97%, an array substrate having a high transmittance can be obtained. Further, since the first undercoat insulating film 12 which is a high refractive index layer is formed as thin as 20 nm with a SiN _X material, the transmittance can be increased. The first undercoat insulating film 12 can increase the transmittance if the film thickness is less than 50 nm, but can increase the transmittance if the film thickness is 30 or less. As described above, a liquid crystal display device with high transmittance can be obtained.

  The first undercoat insulating film 12 has a thickness of 20 nm as described above, and can prevent diffusion of impurities from the glass substrate 10 to the TFT 14 (gate electrode 18 and gate insulating film 17). It is possible to prevent adverse effects. In addition, if the film thickness is 10 nm or more, the 1st undercoat insulating film 12 can suppress the bad influence from the glass substrate 10 given to TFT. Thereby, a liquid crystal display device having a high product yield and excellent product reliability can be obtained.

  From the above, if the thickness of the first undercoat insulating film 12 is 10 nm to 30 nm, a liquid crystal display device with high transmittance and high product yield can be obtained. More preferably, the film thickness of the first undercoat insulating film 12 may be 20 nm to 30 nm, thereby preventing adverse effects from the glass substrate 10 on the TFT.

  Since the thickness of the interlayer insulating film 19 is 445 nm and the thickness of the gate electrode 18 is 250 nm, the thickness of the interlayer insulating film is more than twice the thickness of the gate electrode. Thereby, since the interlayer insulating film 19, particularly the first interlayer insulating film 20, can prevent the diffusion of impurities from the glass substrate 40 to the TFT 14, adverse effects on the TFT can be prevented. The first interlayer insulating film 20 and the second interlayer insulating film 21 can prevent adverse effects from the glass substrate 40 on the TFT if the film thickness is 50 nm or more, respectively. Thereby, a liquid crystal display device having a high product yield and excellent product reliability can be obtained.

  The first interlayer insulating film 20 and the second interlayer insulating film 21 can be formed in a short processing time as long as the film thickness is 1000 nm or less. That is, since the first interlayer insulating film 20 and the second interlayer insulating film 21 are formed using a CVD apparatus, if these film thicknesses exceed 1000 nm, the processing time becomes long, and the processing capacity of the entire production line is reduced. I will let you.

  From the above, if the first interlayer insulating film 20 and the second interlayer insulating film 21 have a film thickness of 50 nm to 1000 nm, a liquid crystal display device with a high product yield can be obtained in a short processing time.

  Since the thickness of the gate electrode 18 is 250 nm as described above, the gate electrode can be formed in a tapered shape on the gate insulating film 17 as shown in FIG. Here, if the thickness of the gate electrode 18 is 100 nm to 500 nm, the gate electrode can be formed in a tapered shape. Thereby, the interlayer insulating film 19 can be satisfactorily formed on the gate electrode 18. When the thickness of the gate electrode 18 is less than 100 nm, the gate electrode is formed in an inversely tapered shape (a state in which the volume is gradually increasing) on the gate insulating film 17. In this case, it is difficult to form the interlayer insulating film 19 satisfactorily, and the product yield is reduced.

  Next, a liquid crystal display device according to another embodiment of the present invention will be described in detail. In this embodiment, other configurations are the same as those of the above-described embodiment, and the same portions are denoted by the same reference numerals and detailed description thereof is omitted.

  As shown in FIG. 12, the liquid crystal display device includes an array substrate 1, a counter substrate 2, a liquid crystal layer 3, a color filter 4, a first polarizing plate 5 and a second polarizing plate 6, and a backlight unit 7. have.

  In this embodiment, the color filter 4 is formed on the counter substrate 2 side. Therefore, the array substrate 1 is formed by forming an insulating planarizing film 26 on the TFT 14, the signal line 22, the contact wiring 25, and the interlayer insulating film 19. Note that a pixel electrode 27 is formed on the planarization film 26.

  In the counter substrate 2, a grid-like black matrix layer 43 is formed on a glass substrate 40. The black matrix layer 43 is formed so as to partition the pixel portion 8. On the glass substrate 40 and the black matrix layer 43, the colored layers 4R, 4G, and 4B are alternately arranged to form the color filter 4. The colored layers 4R, 4G, and 4B are each formed in a stripe shape, and these peripheral portions are disposed so as to overlap the black matrix layer 43.

  A common electrode 41 is formed on the colored layers 4R, 4G, and 4B. An alignment film 42 is formed on the glass substrate 40 on which the common electrode 41 is formed. The liquid crystal display device is completed by assembling a module in the same manner as in the above-described embodiment using the array substrate 1 and the counter substrate 2 described above.

  Next, the reason why the transmittance of the liquid crystal display device of the above-described embodiment is high will be further described. As shown in FIG. 13, the liquid crystal display device has a high refractive index layer in a low refractive index layer (second undercoat insulating film 13, gate insulating film 17 and the like) as in the liquid crystal display device of the above-described embodiment. Since (the first undercoat insulating film 12 and the first interlayer insulating film 20) are sandwiched, interface reflection occurs.

  However, in this embodiment, the film thickness of the first undercoat insulating film 12 is 20 nm, the film thickness of the first interlayer insulating film 20 is 275 nm, and the film thickness of the high refractive index layer is small. As described above, although the liquid crystal display device is formed by sandwiching the high refractive index layer in the low refractive index layer, the film thickness of the high refractive index layer is small, so that the transmittance can be increased.

  Even when the liquid crystal display device is configured as described above, the same effects as those of the above-described embodiment can be obtained, and a liquid crystal display device with high transmittance and high product yield can be obtained.

  The present invention is not limited to the above-described embodiment, and can be variously modified within the scope of the present invention. For example, the interlayer insulating film 19 is formed by laminating the first interlayer insulating film 20 and the second interlayer insulating film 21 in this order on the glass substrate 10, but not limited thereto, the second interlayer insulating film 19 is formed on the glass substrate 10. The insulating film 21 and the first interlayer insulating film 20 may be stacked in this order.

  Here, the inventor of the present application investigated the transmittance of the array substrate 1 when the second interlayer insulating film 21 and the first interlayer insulating film 20 are stacked in this order on the glass substrate 10. At that time, the array substrate 1 was formed without providing the colored layers 4R, 4G, and 4B, the pixel electrode 27, and the alignment film 29. The film thicknesses of the first interlayer insulating film 20 and the second interlayer insulating film 21 were changed in the range of 50 nm to 1000 nm, respectively.

  As shown in FIGS. 14 and 15, the transmittance of the array substrate 1 when the film thicknesses of the first interlayer insulating film 20 and the second interlayer insulating film 21 are changed is known. Examples of the range of the first interlayer insulating film 20 and the second interlayer insulating film 21 whose transmittance is approximately 97% or more include the following (1) to (9).

(1) Second interlayer insulating film: 150 nm to 200 nm
First interlayer insulating film: 50 nm to 1000 nm
(2) Second interlayer insulating film: 350 nm to 400 nm
First interlayer insulating film: 100 nm to 1000 nm
(3) Second interlayer insulating film: 550 nm to 600 nm
First interlayer insulating film: 100 nm to 1000 nm
(4) Second interlayer insulating film: 750 nm to 800 nm
First interlayer insulating film: 100 nm to 1000 nm
(5) Second interlayer insulating film: 900 nm to 950 nm
First interlayer insulating film: 100 nm to 1000 nm
(6) Second interlayer insulating film: 50 nm to 1000 nm
First interlayer insulating film: 150 nm
(7) Second interlayer insulating film: 50 nm to 1000 nm
First interlayer insulating film: 250 nm to 300 nm
(8) Second interlayer insulating film: 50 nm to 1000 nm
First interlayer insulating film: 450 nm
(9) Second interlayer insulating film: 150 nm to 1000 nm
First interlayer insulating film: 600 nm

1 is a perspective view of a liquid crystal display device according to an embodiment of the present invention. Sectional drawing of the liquid crystal display device shown in FIG. The top view which expanded and showed a part of array board | substrate shown in FIG. The figure which showed the structure of the array substrate at the time of investigating the transmittance | permeability of the said array substrate with a table | surface. The figure which showed the change of the transmittance | permeability with respect to the film thickness of the 1st interlayer insulation film of the array board | substrate comprised as shown in FIG. 4, and the 2nd interlayer insulation film. The figure which showed the change of the transmittance | permeability with respect to the film thickness of the 1st interlayer insulation film of the said array board | substrate shown in FIG. The figure which showed the change of the transmittance | permeability with respect to the film thickness of the 1st interlayer insulation film of the said array substrate following the FIG. 6, and the film thickness of the 2nd interlayer insulation film in the table | surface. The schematic block diagram of the liquid crystal display device explaining the optical path of the light radiate | emitted from the backlight unit shown in FIG. FIG. 9 is a partially enlarged configuration diagram showing a part of a liquid crystal display device for explaining transmitted light in the first undercoat insulating film shown in FIG. 8. The figure which showed the structure of the array substrate at the time of investigating the transmittance | permeability of the said liquid crystal display device with a table | surface. The figure which showed the change of the transmittance | permeability with respect to the film thickness of the 1st undercoat insulating film of the liquid crystal display device comprised as shown in FIG. 10 with the graph. Sectional drawing of the liquid crystal display device which concerns on other embodiment of this invention. The schematic block diagram of the liquid crystal display device explaining the optical path of the light radiate | emitted from the backlight unit shown in FIG. The figure which showed the change of the transmittance | permeability with respect to the film thickness of the 1st interlayer insulation film of the array board | substrate of the modification of the said embodiment, and the 2nd interlayer insulation film with a table | surface. The figure which showed the change of the transmittance | permeability with respect to the film thickness of the 1st interlayer insulation film of the said array substrate, and the film thickness of a 2nd interlayer insulation film following the FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Array substrate, 2 ... Counter substrate, 3 ... Liquid crystal layer, 4 ... Color filter, 7 ... Backlight unit, 8 ... Pixel part, 10 ... Glass substrate, 11 ... Undercoat insulating film, 12 ... 1st undercoat insulation Film, 13 ... second undercoat insulating film, 14 ... TFT, 15 ... channel layer, 17 ... gate insulating film, 19 ... interlayer insulating film, 20 ... first interlayer insulating film, 21 ... second interlayer insulating film, 22 ... Signal lines, 23... Scanning lines, 27... Pixel electrodes, 40.

Claims (6)

An array substrate having a substrate, a plurality of switching elements formed on the substrate, an interlayer insulating film formed on the switching elements, and a plurality of pixel electrodes formed on the interlayer insulating film; ,
A counter substrate disposed opposite to the array substrate with a gap;
A liquid crystal layer sandwiched between the array substrate and the counter substrate,
The interlayer insulating film includes a first interlayer insulating film formed from SiN _{X to} a thickness of 50 nm to 1000 nm, and a second interlayer insulating film formed from SiO _X material to a thickness of 50 nm to 1000 nm. A liquid crystal display device which is laminated and formed to have a film thickness in which the transmittance of the array substrate exceeds 97%. The switching element is a thin film transistor having a channel layer formed on the substrate, a gate insulating film formed on the channel layer, and a gate electrode formed on the gate insulating film,
The liquid crystal display device according to claim 1, wherein the interlayer insulating film is formed on the gate electrode, and the film thickness of the interlayer insulating film is twice or more the thickness of the gate electrode.   The liquid crystal display device according to claim 2, wherein the gate electrode has a thickness of 100 nm to 500 nm. The liquid crystal display device according to claim 1, wherein the array substrate includes an undercoat insulating film formed on the surface of the substrate with a film thickness of 10 nm to 30 nm using a SiN _X material.   The liquid crystal display device according to claim 1, wherein the interlayer insulating film is laminated on the substrate in the order of the first interlayer insulating film and the second interlayer insulating film.   2. The liquid crystal display device according to claim 1, wherein the interlayer insulating film is laminated on the substrate in the order of the second interlayer insulating film and the first interlayer insulating film.

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