JP2003167103A - Method of manufacturing inclined diffuse reflection body and structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suggest a new manufacturing process for an inclined diffuse reflection body and to propose a structure. <P>SOLUTION: Optical masks including a plurality of half tone exposure units 72 are used. A half tone photolithography process is performed for a positive light resist formed on a substrate. Only one exposure process and an appropriate drying step are enough for forming a plurality of inclined faces 84 and forming coarse astigmatism on the inclined faces 84. The sizes of a half tone exposure units 72 are selected at random. Each of the half tone exposure units 72 includes a plurality of parallel transmissive strips or shadow strips 74. The pitch of the transmissive strips or shadow strips 74 in a single half tone exposure unit 72 is arbitrary. The width of the shadow strips 74 gradually varies from one side of the half tone exposure units 72 to the other side. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to diffuse reflectors applied in reflective LCDs, and more particularly to processes and structures for graded diffuse reflectors.

[0002]

2. Description of the Related Art A reflective LCD usually consists of an upper polarizer, a liquid crystal cell, a lower polarizer and a diffuse reflector. The liquid crystal cell consists of two parallel glass laminates and a liquid crystal material filled in the space between the two glass laminates. The matching layer and the transparent electrode film are formed on the inner surfaces of the two glass laminated plates. Generally, the user views the image from the LCD at a right angle, but the light is LC
D is transmitted in a non-perpendicular direction. For example, light is transmitted from somewhere above the LCD in the 12 o'clock direction relative to the LCD. The light passes through the upper polarizer, the liquid crystal cell and the lower polarizer, then is reflected by the diffuse reflector, passes through the lower polarizer, the liquid crystal cell, the upper polarizer, and finally becomes the signal beam. It becomes visible to the human eye. How to design a good diffuse reflector with high light efficiency is an important issue in reflective LCD structures. Methods of increasing the intensity of visible light and simplifying the manufacturing process are important issues for manufacturing diffuse reflectors. The inclined diffuse reflector reflects the non-mirror image of the incident light and the signal light, thereby separating the signal light and the glare generated by the glass laminated plate (or the polarizer) and increasing the utilization efficiency of the incident light. It includes an angle that allows you to. Therefore, the quality of the reflective LCD is improved.

The conventional method of manufacturing a tilted diffuse reflector requires two different photomasks for two different photoexposure processes. Usually, the optical register on the substrate is exposed to form an inclined surface and then exposed again to form bumps to obtain astigmatism on the inclined surface. The traditional method requires two exposures, which makes the manufacturing process very complicated and the production cost very high. Therefore, there is a need to provide new manufacturing processes and structures for graded diffuse reflectors.

[0004]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to simplify the manufacturing process and reduce costs, and to propose a new manufacturing process and structure for a graded diffuse reflector.

To this end, halftone photolithography is performed on the positive photoresist on the substrate using a special photoresist. Slanted structures and bumps can be formed on a photomask in just one photolithography process. This special photomask contains multiple halftone exposure units. The size of the halftone exposure unit can be arbitrarily set. Each of the halftone exposure units
It includes a plurality of parallel transmission strips or shadow strips. The transparent strips or shadow strips have any suitable but arbitrary shape. In the same halftone exposure unit,
The pitch between the transparent strips or the shadow strips can be arbitrarily set. The width of the transparent strip or shadow strip is
It increases unilaterally from one side of the halftone exposure unit to the other (ie decreases in the opposite direction). As soon as the photomask is run and the out-of-focus exposure is performed on the photoresist, the distance between the photoresist and the focal point is adjusted, which allows light to enter the halftone unit and zigzag on the photoresist. A distribution of light intensity (light intensity changes from strong to weak or from weak to strong) occurs. After this out-of-focus exposure process is performed, the appropriate development and drying processes are also performed to form bumps of random size to obtain astigmatism on the tilted surface.

The method of manufacturing a slanting diffuse reflector has the following steps, eg, PC403, PC409 or PC.
Providing a substrate on which a positive photoresist such as 452 is formed, and providing an optical mask including a plurality of halftone exposure units each including a plurality of parallel transmission strips or shadow strips, Arbitrarily selecting the pitch between Tokai strips or shadow strips on the same halftone exposure unit and gradually reducing the width of the shadow strips from one side to the other; The method includes forming a sloped surface including a plurality of bumps using a mask, and finally drying the photoresist. The size of the halftone exposure unit and the pitch between the transparent strips or shadow strips,
LCD that corresponds to a photomask with a gradually changing width of a transmission strip or a shadow strip in a halftone exposure unit
It is preferably distributed arbitrarily within the range of pixels. This way, the beveled surface on the photoresist provides better astigmatism capability after combining subsequent processes.

The above process of drying the photoresist includes the step of solidifying the ramped surface of the photoresist after it has been developed. Since the photoresist flows by heating before it completely solidifies, the bumps on the sloped surface are less noticeable and reduce the astigmatic function of the photoresist. A better method of drying the photoresist is the next step, i.e.
Dry at 150 ° C. for 5-30 minutes, then about 20
Hard baking at 0 ° C. for more than 1 hour. In this case, the fluid behavior of the photoresist, which makes the bumps less noticeable, is reduced.

Further, the structure of the inclined diffuse reflector according to the present invention is formed on the substrate, the photoresist formed on the substrate, the plurality of inclined surfaces formed on the photoresist, and each inclined surface. Made of multiple bumps, made of. The bump for providing the astigmatism may be ripple. The length of the beveled edge is in the range of about 10-40 microns. A better situation is to set the random size of the inclined surface within the range of one pixel to improve the astigmatism function. If the inclined surface is different, the pitch of the ripple on it may be randomly determined.

Further areas of applicability of the present invention will be apparent upon reading the detailed description below. It should be understood, however, that this detailed description and specific examples, while indicating preferred embodiments of the present invention, are provided for purposes of illustration, which is a detailed description thereof. It will be apparent to those skilled in the art from the description that various changes and modifications can be made within the spirit and scope of the present invention.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Please refer to FIG. 1 for the method of manufacturing the slanting diffuse reflector disclosed in the present invention. Substrate 20 is provided, which may be a metal substrate, a glass substrate, a plastic substrate or any other suitable substrate. A positive photoresist 25 is formed on the substrate 20. This positive photoresist is a positive photoresist PC manufactured by JSR Japan.
It may be 403.

Next, a special photomask 30 is provided. As shown in FIG. 2, the photomask 70 includes a plurality of halftone exposure units 72, which perform an out-of-focus halftone exposure 40 on the substrate. Each halftone exposure unit 72 includes a plurality of parallel shadow strips 7.
Includes 4. The pitch between the shadow strips 74 is
It may be fixed in the same halftone exposure unit 72. The width of shadow strip 74 gradually decreases from one side of halftone exposure unit 72 to the other side. The manner in which the width of the shadow strip changes can be adjusted. Halftone exposure unit 72
, The pitch of the shadow strips, and the width of the shadow strips, which varies gradually with different halftone exposure units 72, are arbitrarily distributed within the LCD pixel range 75 corresponding to the photomask 70. It is preferable. This way
The randomly distributed slopes on the photoresist provide better astigmatism capability after subsequent defocus exposure step 40 and development step 50 combination.
Those skilled in the art should understand that the present invention is not limited to randomly distributing inclined surfaces of various sizes within the range of one pixel. The photomask can also be designed such that inclined surfaces of different sizes are randomly distributed in all areas. The halftone exposure units 72 each have an adjacent light transmission region 73. The width of the light transmission region 73 is, for example, 1 to 3 μm. This allows the inclined surface corresponding to the halftone exposure unit 72 to have a horizontally rounded surface. Thus, the light diffusion rate is increased.

An out-of-focus halftone exposure 40 is shown in FIG.
Shown in. A photomask is placed on the photo resist 82 formed on the substrate 80. The light 90 is applied and the exposure step is performed. By adjusting the out-of-focus distance of the photo resist 82, a halftone (gradual change from strong to weak or from weak to strong) zigzag light intensity distribution 92 is obtained when the light 90 passes through the halftone exposure unit 72. Formed on. After the out-of-focus exposure, a suitable development step 50 is performed to form the ramp 80 as shown in Figure 3B. A plurality of ripple-shaped astigmatism bumps 86 are formed on the inclined surface 84. In the developing step 50 described above, a developer (for example, 2.38% T manufactured by JSR
PD523AD developer containing MAH) as a photo resist 8
2 is coated and the development is completed.

After the developing step 50, a drying step 60 is performed on the photoresist 82 to solidify the photoresist 82. Since the photoresist 82 flows by heating before being completely solidified, the bumps 86 on the inclined surface 84 are formed.
Are less noticeable, thus reducing the astigmatism of the photoresist. As a better method, a photo resist 82
Is soft baked for a period of time at a lower temperature to partially solidify the photoresist 82, and then hard bake at a higher temperature to completely solidify the photoresist 82. For example, soft bake at 100-150 ° C. for 5-30 minutes, then hard bake at about 220 ° C. for one and a half hours. In this case, it is possible to maintain the original shape of the bumps, thus preventing fluid movement of the photoresist that makes the bumps inconspicuous.

Upon completion of the drying step 60, the graded diffuse reflector is then subjected to atomic force microscopy (AF) as shown in FIG.
M). The plurality of inclined surfaces 84 are the photoresist 82.
Formed on. The height of the inclined surface 84 is 0.5 to 3
A range of μm is desirable. A better situation is to arrange the inclined surface 84 randomly within the range of one LCD pixel. This increases the light diffusion rate,
Further, the diffraction of light that occurs when the inclined surfaces 84 are uniformly arranged is prevented. If a metal layer having high reflection characteristics is formed on the photoresist 82, the light reflectance can be increased. This metal layer is, for example, silver, aluminum, or another metal having high reflection characteristics.

FIG. 5 shows an enlarged structure of one inclined surface 84. The angle of the inclined surface 84 on the substrate 80 is, for example, 4 to 4.
It is 5 degrees. The length of the edge of the inclined surface 84 is about 10-4.
It is 0 micron. In order to obtain a better light reflectance, the pitch d ₂ between the ripple-shaped bumps 86 on the various inclined surfaces 84 may be arbitrarily determined.

According to the manufacturing method and structure of the present invention, when a special photomask is used, only one exposure process is required to simultaneously obtain an inclined surface and astigmatism on the inclined surface. Therefore, the manufacturing process is simplified and the cost is reduced.

As mentioned above, the present invention can be variously modified. It is obvious to those skilled in the art that such modifications are not considered to depart from the spirit and scope of the present invention, and all such modifications are intended to be included in the scope of the claims. Let's do it.

[Brief description of drawings]

FIG. 1 is a flow chart for manufacturing a tilted diffuse reflector of the present invention.

FIG. 2 is a diagram of a photomask structure including a plurality of halftone exposure units according to the present invention.

FIG. 3A: Defocused halftone exposure diagram according to the present invention. (B): View of the sloped surface formed on the photoresist after the out-of-focus exposure and development steps according to the present invention.

FIG. 4 is a diagram of a structure of a slanting diffuse reflector according to the present invention.

FIG. 5 is an enlarged view of one tilted surface on a tilted diffuse reflector.

[Explanation of symbols]

20 substrates 25 positive photoresist 30 light mask 40 Halftone exposure (exposure step) 50 development steps 72 Halftone exposure unit 73 Light transmission area 74 Shadow Strips 75 range 80 substrate (slope) 82 Photoresist 84 inclined surface 86 bumps 90 light 92 Light intensity distribution

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H042 BA03 BA12 BA14 BA20 DA02                       DA04 DA09 DA14                 2H091 FA16Z FB08 FC10 FD04                       FD06 LA12

Claims (18)

[Claims] 1. A step of providing a substrate, a step of forming a positive or negative photoresist on the substrate, and a step of providing an optical mask, wherein the optical mask comprises:
A plurality of halftone exposure units, each of the halftone exposure units including a plurality of parallel transmission strips or shadow strips; and using the photomask to perform an out-of-focus exposure and development step. Thereby forming a plurality of inclined surfaces having bumps on the photoresist, drying the photoresist, and forming a metal layer having a high reflectance on the photoresist. A method for manufacturing a tilted diffuse reflector, comprising at least. 2. The method of claim 1, wherein the edge of the slanted surface is about 10-40 microns. 3. The tilted diffuse reflector according to claim 1, wherein the pitch between the shadow strips in each of the halftone exposure units is the same or arbitrary, and the width of the shadow strips is gradually changed. Production method. 4. The method of claim 3, wherein the shadow strip size is randomly selected within a range. 5. The pitch between the transmission strips or shadow strips of the halftone exposure unit and the method of changing the width are randomly selected within a certain range,
The method for manufacturing a tilted diffuse reflector according to claim 4. 6. The method for manufacturing a tilted diffuse reflector according to claim 5, wherein the certain range is a pixel range. 7. The PC4 manufactured by JCR is used as the photoresist.
03, PC409 or PC452 positive photoresist, The inclined diffuse reflector manufacturing method of Claim 1. 8. The method of claim 7, wherein the photoresist drying step comprises a soft bake at 100 to 150 ° C. for 5 to 30 minutes and a hard bake at about 220 ° C. for one and a half hours. Method for manufacturing a tilted diffuse reflector of. 9. The method of claim 1, wherein the high reflectance metal layer is selected from the group consisting of silver, aluminum and other high reflectance metals. 10. The tilted diffuse reflector according to claim 1, wherein each of the halftone exposure units has horizontally adjacent light transmission regions, and the widths of the light transmission regions are 1 to 3 microns. Production method. 11. A substrate, a photoresist formed on the substrate, wherein the photoresist has a plurality of inclined surfaces, and a plurality of bumps formed on each of the inclined surfaces. And a metal layer covering the photoresist, and a structure of the inclined diffuse reflector. 12. The length of the edge of the inclined surface is about 10.
12. The graded diffuse reflector structure of claim 11, which is -40 microns. 13. The structure of a tilted diffuse reflector according to claim 11, wherein the size of the tilted surface is randomly selected within a range. 14. The structure of the tilted diffuse reflector according to claim 13, wherein the bump has a ripple-shaped structure. 15. The pitch between ripples on the inclined surface is randomly selected within the certain range.
4. The structure of the inclined diffuse reflector according to item 4. 16. The method according to claim 1, wherein the certain range is pixels.
5. The structure of the inclined diffuse reflector according to item 5. 17. The high reflectance metal layer is selected from the group consisting of silver, aluminum and other high reflectance metals.
The structure of the inclined diffuse reflector according to claim 11. 18. The height of the inclined surface is 0.5 to 3 μm.
The structure of the inclined diffuse reflector according to claim 11, which is in the range of.