Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Making named article
Reexamination Certificate
2002-05-08
2004-08-10
McPherson, John A (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Making named article
C430S396000
Reexamination Certificate
active
06773870
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a diffusive direct reflector manufacturing process, especially to a process of manufacturing diffusive direct reflector by Gray tone exposure, which uses a controllable transmittance Gray tone mask to produce the desired slant changes on a photoresist layer through a one-step exposure process and form the desired diffusive direct reflector.
2. Description of Related Art
FIG. 1
is a schematic diagram of the profile of a perfect diffusive direct reflector. As shown in
FIG. 1
, ideally, a perfect diffusive direct reflector has a slope with an angle &thgr;1 on the photoresist layer such that the incident lights r
1
, r
2
can be reflected by the slope in a direction vertical to the lower substrate
10
. As such, the reflected lights r
1
′, r
2
′ reaching the human eye is the brightest. Further, the bumps on the slope can increase viewing angle due to the adaptive astigmatistic effect on r
1
′ and r
2
′. With such a structure, a diffusive direct reflector can meet the display requirements of separating reflective image and surface glare and increasing viewing angle. For meeting the requirements, a two-step exposure process is used as shown in FIG.
2
. In
FIG. 2
, the first-step exposure process produces the slope with the angle &thgr;1 while the second-step exposure process smoothes the slope produced by the first-step exposure process to control the astigmatistic angle. As shown in
FIG. 2
, for producing a slant structure in the first-step exposure process, a chromium film photomask as shown in
FIG. 3
is used to operate multiple exposures on the photoresist layer. Such a photomask as shown in
FIG. 3
must have multiple strip patterns with equal widths and have equal pitches between the strips. In practice, each exposure must shift the photomask a finite distance and produce the slant structure
21
according to increasing or decreasing exposure energy. The increasing or decreasing exposure energy can produce different exposure depth on the photoresist. The finite distance can not only retain previous major exposure depth but also produce an appropriate overlapping area
22
with different exposure depths due to two successive exposures. As such, the slant is formed. At this step, the resulting slant is a ladder profile that cannot control the required astigmatistic angle. In order to control the required astigmatistic angle, using the second-step exposure process forms a smooth profile
23
on each ladder
21
of the slant surface. In the second-step exposure process, any photomask pattern such as circle, triangle, and so on, able to produce 10-30 degrees astigmatistic angle can be used to form a desired slant. However, the complicated exposure procedures take time and cost and may further influence the resulting reflector's quality. For example, when the required slant is formed closer to a perfect reflector as shown in
FIG. 1
, the exposure frequency increases in the first-step exposure process and the smoothing profile processing control becomes harder in the second-step exposure process. On the other hand, the lower exposure frequency causes reduced precision and further reduces light efficiency so that the resulting reflector has poor quality.
SUMMARY OF THE INVENTION
Accordingly, an object of the invention is to provide a method of manufacturing a diffusive direct reflector using Gray tone exposure, which uses a controllable transmittance photomask to produce the desired slant by a one-step exposure process, thereby simplifying processing, increasing field and saving cost.
Another object of the invention is to provide a method of manufacturing a diffusive direct reflector using Gray tone exposure, which uses a controllable transmittance photomask to form the desired slant and bump by a one-step exposure process so as to control the reflective angle and astigmatistic range of an incident light, thereby increasing the exposure processing productivity.
The method of manufacturing a diffusive direct reflector using Gray tone exposure, comprising the steps: performing the exposure and development processes on a photoresist layer over a substrate using a controllable transmittance photomask pattern. As such, a gradually changing transmittance is obtained by one-step exposure using the photomask pattern and the desired slant is formed. Further, bumps with astigmatistic mechanism can be arranged into the photomask pattern to produce the desired structure with slants and bumps on the photoresist layer at one-step exposure.
Further scope of the applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
REFERENCES:
patent: 6084656 (2000-07-01), Choi et al.
patent: 6163405 (2000-12-01), Chang et al.
patent: 2002/0163608 (2002-11-01), Ting et al.
patent: 2003/0096198 (2003-05-01), Wong et al.
patent: 2002-090511 (2002-03-01), None
Lai Chih-Ming
Liao Chi-Chang
Wong Yichun
Birch & Stewart Kolasch & Birch, LLP
Industrial Technology Research Institute
McPherson John A
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