Radiation imagery chemistry: process – composition – or product th – Radiation modifying product or process of making – Radiation mask
Reexamination Certificate
1998-08-26
2002-01-22
Huff, Mark F. (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Radiation modifying product or process of making
Radiation mask
C428S014000
Reexamination Certificate
active
06340541
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device, and in particular to an improved mask for recycling and a fabrication method capable of recycling the mask.
2. Description of the Conventional Art
In semiconductor device fabrication, a light exposing process for forming a pattern on a semiconductor substrate is called a photolithography process.
The photolithography process will be described hereinbelow. First, a photoresist film, which reacts to a light, is applied on a semiconductor substrate, and a mask having a pattern provided with a light transmitting unit and a non-transparent unit is formed on the semiconductor substrate. The mask is irradiated by an irradiator. Therefore, the photoresist film on the semiconductor substrate reacts to the light passing through the light transmitting unit. When the semiconductor substrate is put into a developing solution, the portion of the photoresist film that reacts to the light is removed, or the other portion of the photoresist fiber that does not react to the light is removed, a pattern being formed on the semiconductor substrate in either case.
A conventional mask applied to the photolithography process is illustrated in
FIGS. 1 and 2
.
FIG. 2
is a vertical cross-sectional view taken along the line II-II′ in FIG.
1
.
A thin film
1
is provided with a plurality of non-transparent patterns
3
of a predetermined shape, positioned at a central portion of an optically transparent substrate
2
having a predetermined thickness.
A pellicle frame
6
having a predetermined height surrounds the patterns
3
of the thin film
1
, a hole being formed in a central part of the pellicle frame
6
. The pellicle frame
6
is attached to each marginal portion of upper and lower surfaces
1
a,
1
b
of the substrate of the thin film
1
. A pellicle
7
, that is a pattern protection film, is attached to top and bottom surfaces of each pellicle frame
6
which is attached to the upper and lower surfaces
1
a,
1
b,
respectively, of the thin film
1
. Since each pellicle
7
is attached to the pellicle frame
6
by an adhesive, the pellicle
7
and the thin film
1
are fixed together and inseparable from each other. Here, the pellicle
7
protects the patterns
3
formed on the substrate
2
.
A fabrication method of the conventional mask will now be described.
First, the thin film
1
is fabricated. That is, a thin layer of a material that is not optically transparent, such as chromium (Cr), is applied to a surface of the optically transparent substrate
2
, which substrate is flat has a predetermined thickness, thus forming a chrome film. Next, a resist film that reacts to light or electron beams is applied on the chrome film, and the resist film is exposed to a desired pattern of light projected by a light exposing apparatus or an electron beam irradiator. The irradiated resist film is thus developed to form a resist pattern. The chrome film is etched using the resist pattern as the protection film, thereby forming the non-transparent patterns
3
. As described above, the non-transparent patterns
3
of the chrome film are formed on one side
1
a
of the thin film
1
, and the other side
1
b
thereof remains optical-transparent glass material.
In the photolithography process, a part of the substrate of the thin film having each non-transparent pattern
3
formed thereon does not transmit light, but other parts of the substrate of the thin film that do not have the non-transparent patterns
3
formed thereon transmit light. However, when the part of the transparent substrate
2
not having the non-transparent patterns
3
formed thereon is externally damaged or has a foreign substance thereon, a pattern which is different from the desired pattern is formed on the substrate
2
and thus by the thin film as a whole. For that reason, it is necessary to provide a protection film, that is the pellicle
7
, for protecting the both sides
1
a,
1
b
of the thin film
1
.
Accordingly, the pellicle frame
6
is attached to each marginal portion of the upper and lower surfaces
1
a,
1
b
of the thin film
1
, and each pellicle
7
is attached to the pellicle frame
6
in order to cover the patterns
3
. The thusly fabricated mask provided with the thin film
1
, the pellicle frames
6
, and the pellicles
7
can be used almost permanently.
However, when a product using the conventional mask is not manufactured, the thin film
1
of the mask becomes needless. Accordingly, although the pellicle frame
6
and the pellicle
7
for protecting the thin film
1
may be useful for protecting other objects/films, they are rendered useless since they are attached by an adhesive to the obsolete mask. Thus, because the pellicle frame
6
and the pellicle
7
are inseparable from the thin film
1
, the whole mask must be disposed.
Also, although the price of the mask varies based on the manufacturing difficulty of the thin film
1
, it is generally expensive for conventional devices as described above. Accordingly, disposing of the whole mask is very costly. In addition, disposing of the whole mask is environmentally wasteful.
SUMMARY OF THE INVENTION
The present invention is directed to a mask and fabrication method that substantially obviates one or more of the problems experienced due to the above and other limitations and disadvantages of the conventional art
It is an object of the present invention to provide a recyclable mask and a fabrication method thereof, where the mask may be recycled by replacing only a thin film of a predetermined pattern formed in the mask, without discarding the whole mask.
Other and further objects, features and advantages of the present invention will be set forth in the description that follows, and in part will become apparent from the detailed description, or may be learned by practice of the invention.
To achieve these and other objects and advantages and in accordance with the purpose of the present invention, as embodied and broadly described, there is provided a mask for recycling which includes: a thin film having predetermined-shaped patterns; a pair of solid mask frames placed on each marginal portion of upper and lower surfaces of the thin film, and respectively having an opening in the center thereof; a plurality of mask frame holders for fixing the mask frames and the thin film as a single body; a pellicle frame which is attached to each portion of top and bottom surfaces of each mask frame; and a pellicle attached to top and bottom surfaces of each pellicle frame.
Additionally, to achieve the above and other objects and advantages, there is provided a fabrication method for a mask for recycling, including: fabricating a thin film; placing a mask frame on each portion of upper and lower surfaces of the thin film; fixing the mask frames; attaching each pellicle frame to top and bottom surfaces of the mask frames, respectively; and attaching each pellicle to top and bottom surfaces of the pellicle frames.
The fabricating step may include applying a non-transparent layer on an optical-transparent substrate, forming a resist pattern on the non-transparent layer, and etching the non-transparent layer with the resist pattern as a mask, thus forming non-transparent layer patterns.
Also, the fabricating step may include forming a resist pattern on a non-transparent substrate for intercepting light, and selectively etching and opening the non-transparent substrate with the resist pattern as a mask, thereby forming transparent patterns. In addition, the fabricating step may further include filling up substance for transmitting light in an open portion of the non-transparent substrate.
There may also be provided a mask recycling method which includes: separating mask frame holders from mask frames; removing a thin film placed between the mask frames; inserting a new thin film between the mask frames; and fixing the mask frames and the thin film with the mask frame holders.
It is to be understood that both the foregoing general description and the following detai
Huff Mark F.
Hyundai Electronics Industries Co,. Ltd.
Mohamedulla Saleha R.
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