Data processing: generic control systems or specific application – Specific application – apparatus or process – Product assembly or manufacturing
Reexamination Certificate
2002-05-10
2004-10-05
Rodriguez, Paul (Department: 2125)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Product assembly or manufacturing
C700S110000, C438S014000, C702S081000
Reexamination Certificate
active
06801824
ABSTRACT:
TECHNICAL FIELD
The present invention relates to substrate-selecting equipment for a photomask used for the production of a semiconductor integrated circuit and in particular to substrate-selecting equipment for selecting a substrate used for an objective product from among a group of substrates with photosensitive material layer used for the production of photomasks.
BACKGROUND ART
In recent years, the desire for high-integration and high-function has increased for various LSI typified by ASIC as a result of the tendency of electric equipment becoming more efficient, lighter, thinner, shorter and smaller. In a photomask used for the production of a semiconductor integrated circuit, forming patterns of a photomask with high efficiency and high quality has come to be desired.
Heretofore, the production of a photomask is carried out generally through the steps shown in FIG.
8
.
First, as shown in FIG.
8
(
a
), a substrate (it is called “blanks”) provided with a shielding film or shifter layer
820
made of a metallic thin film such as chromium formed on a transparent substrate
810
by sputtering and others is provided.
Then, as shown in FIG.
8
(
b
), a photosensitive material layer
830
such as a photosensitive resin film, photosensitive resist or merely resist is laminated on a shielding film or shifter layer
820
, and then dried by heating to remove any solvent remaining in the photosensitive material layer and to improve the adhesion between the metallic thin film
820
and the transparent substrate
810
.
Then, as shown in FIG.
8
(
c
), ionizing radiation
840
, such as an EB (Electron Beam), a laser beam, or an X-ray, is applied so as to selectively expose the ionizing radiation
840
into a desired pattern. Generally, the ionizing radiation
840
is selectively exposed by the fixed equipment according to pattern data for the formation of the pattern. Therefore, it is also called “pattern writing” or merely “writing”.
Then, as shown in FIG.
8
(
d
), the photosensitive material layer
830
is developed to form a resist pattern
835
. Thereafter, as shown in FIG.
8
(
e
), areas of the shielding layer
820
made of the metallic thin film exposed within the openings
836
of the resist pattern
835
are etched so that shielding layer pattern
825
is formed.
Finally, the resist pattern
835
is removed so that a photomask formed from the shielding layer pattern
825
can be obtained, as shown in FIG.
8
(
f
). Thereafter, inspection and correction of pattern are carried out according to demand so that a desired photomask is obtained.
The quality of photomask produced in the above-mentioned process is greatly affected by the quality of the substrate with a photosensitive material layer employed for pattern writing. Since there are many types of substrates having a photosensitive material layer thereon, the control of substrates having a photosensitive material layer thereon is difficult. Heretofore, the distinction between good products and poor products is carried out according to the regular standard in the inspection in the process of production so that only good products are employed.
However, the specifications of quality for objective products are various, and substrates with photosensitive material layers distinguished as good products are varied in the phase of quality and the sensitivity of photosensitive material layers. Therefore, substrates corresponding to the specifications of objective products are not always selected. Accordingly, there are cases where the influence of the used substrate on the inspection and correction thereof was considerable.
Further, as circuits of semiconductor products such as LSI chips increase in density, the desire for the formation of patterns having higher accuracy and quality has also increased.
It is an object of the present invention to provide a substrate-selecting equipment wherein substrates used for the production of objective products can be successfully selected from among a group of substrates with photosensitive material layers used for the production of photomasks employed for writing of patterns in the process of photomask, particularly from the phase of quality of products.
DISCLOSURE OF THE INVENTION
The present invention is a substrate-selecting equipment for selecting substrates used for objective products from among a group of substrates with photosensitive material layers used for the production of photomask, wherein the substrate-selecting equipment comprises one or more of the defect-registering part(s) for registering the results of the inspection of defects of substrates with photosensitive material layers in database, the photosensitive material layer lot check result-registering part for registering the results of check of lots of photosensitive material layers in database and the substrate-selecting part for selecting substrates used for the production of objective products from among a group of substrates with photosensitive material layers, on the basis of the results of inspection of defects and the results of check of lots of photosensitive materials registered in database.
Further, in the above-mentioned substrate-selecting equipment, the defect-registering part is comprised of the pinhole defect-registering part for registering the results of inspection of pinhole defects of blanks in which photosensitive material layers are not laminated on substrates in database and the foreign substance defect-registering part for registering the results of inspection of foreign substance in database.
Furthermore, the above-mentioned substrate-selecting equipment further comprises the selection standard-registering part for registering the quality standard of substrates which is the standard of selection of substrates in database, wherein the substrate selection part selects substrates used for the production of objective products, on the basis of the information on the results of check of lots of photosensitive material layers and the quality standard of substrates which is the standard of the selection of substrates, according to demand.
Further, the above-mentioned substrate-selecting equipment further comprises the in pattern area existing defect extracting part for extracting defects existing in a pattern area on a photomask. For the substrate produced, defects existing in a pattern area on a photomask are extracted on the basis of the information from the results of inspection of defects of each substrate and on the basis of the information from the results of check of lots of photosensitive material layers registered in database.
Further, the above-mentioned substrate-selecting equipment further comprises the defect probability-calculating part for calculating the probability that no defect happens or the probability that happen in the surrounding part of a pattern of photomask produced or for calculating the probability that no defect happens or the probability that defects happen inside a pattern of photomask produced, corresponding with the patterns of photomask produced every substrate, on the basis of the information on the results of inspection of defects of each substrate and the information on the results of check of lots of photosensitive material layers registered in a database for candidate substrate nominated for candidate of substrate used for photomask to be produced, and wherein the substrate-selecting part selects substrates used for the production of objective products, on the basis of the probability that no defect happens or the probability that defects happen in the surrounding part of pattern every substrate obtained in the defect probability-calculating part, or from the probability that no defect happens or the probability that defects happen over the whole of pattern, according to demand.
Further, in the above-mentioned substrate-selecting equipment, in the defect probability-calculating part, defect areas having the size larger than the size of defects decided considering errors, corresponding to the position of defect on photomask to be produced, are obtained for all the defe
Ishida Kouji
Nara Hideyuki
Seino Hajime
Yamazaki Kiyoshi
Dainippon Printing Co., Ltd.
Rader & Fishman & Grauer, PLLC
Rodriguez Paul
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