Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Making named article
Reexamination Certificate
1998-05-07
2001-06-05
Angebranndt, Martin (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Making named article
C430S320000, C430S945000, C430S394000, 30
Reexamination Certificate
active
06242162
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for manufacturing a master disk used for manufacturing an optical disk which is an optical recording/reproducing medium, and to the master disk.
2. Description of Related Art
In general, a high density optical disk such as a digital versatile disk (DVD)—random access memory (RAM) includes grooves
1
and lands
2
where information are recorded along spiral tracks, as shown in FIG.
1
. Also, pits
3
are formed on the grooves
1
and the lands
2
, respectively, to thereby record desired information thereon. Since both the grooves
1
and the lands
2
are used for recording information thereon, more information can be recorded as compared to a conventional disk in which either the groove
1
or the land
2
has been used for recording.
The optical disk is manufactured through processes as shown in
FIGS. 2A through 2D
. As shown in
FIG. 2A
, a photoresist
20
is coated on a substrate
10
, and then the photoresist
20
is simultaneously exposed to a laser
30
for a groove and a laser
30
′ for a pit according to patterns of the groove
1
, the land
2
and the pit
3
while rotating the substrate
10
. Reference numerals
31
and
31
′ indicate modulators for turning on/off the lasers
30
and
30
′, respectively.
Subsequently, as shown in
FIG. 2B
, an etching reagent is sprayed on the exposed substrate
10
, to thereby manufacture a master disk
15
where grooves, lands and pits are formed.
A son disk
25
is formed by stamping the master disk
15
as shown in
FIG. 2C
, and then an optical disk is copied by an injection molding method in which resin
35
is injected into a mold
40
having the son disk
25
mounted thereon, as shown in FIG.
2
D.
However, in the above method, the lands, the grooves and the pits are formed on one photoresist layer by simultaneously exposing and etching the same, so that boundaries among the land, the groove and the pit are not sharp.
Accordingly, start and end points of information signals are not accurately detected during reproduction, which may cause jitter errors in which an output signal is not appropriately generated on time.
SUMMARY OF THE INVENTION
To solve the above problems, it is an object of the present invention to provide a method for manufacturing a master disk used for forming an optical disk, by which a great deal of information is recorded at a high density and a jitter error ratio thereof is reduced.
Additional objects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Accordingly, to achieve the above and other objects of the present invention, a master disk manufacturing method of the present invention includes the steps of forming a SiO
2
film on a substrate; coating a first photoresist layer on the SiO
2
film; exposing the first photoresist layer according to a pattern of a groove formation recess and a land formation protrusion corresponding to a groove and a land, respectively; etching the first photoresist layer and the SiO
2
film, to thereby form the groove formation recess and the land formation protrusion on the SiO
2
film; coating a second photoresist layer on the SiO
2
film, to thereby form the groove and the land; exposing the second photoresist layer according to patterns of a pit where predetermined information is recorded; and etching the second photoresist layer, to form the pits in the groove and the land.
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Abstract of JP 08-241541, Sep. 22, 1996.*
Merck Index tenth Ed. pp. 1220, citation for silicon dioxide, 1983.
Ahn Young-man
Park Chang-min
Ro Myong-do
Angebranndt Martin
Samsung Electronics Co,. Ltd.
Staas & Halsey , LLP
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