U.S. patent application number 10/659440 was filed with the patent office on 2004-03-11 for mold and method of producing the same.
Invention is credited to Kosuga, Hiroyuki, Yokoo, Yoshiatsu.
Application Number | 20040047938 10/659440 |
Document ID | / |
Family ID | 27311330 |
Filed Date | 2004-03-11 |
United States Patent
Application |
20040047938 |
Kind Code |
A1 |
Kosuga, Hiroyuki ; et
al. |
March 11, 2004 |
Mold and method of producing the same
Abstract
(1) Alignment mark transfer portion(s) is/are formed on the
transfer molding surface of a mold that is used for press-molding a
optical element fixing member and having alignment marks; (2)
alignment mark(s) is/are formed on the mold material by
dry-etching, and the mold material is worked using the alignment
mark(s) as a reference to form the transfer molding surface
constituted by a plurality of transfer patterns, in order to obtain
a mold for press-molding; and (3) the transfer patterns are formed
by dry-etching, or a transfer molding bare surface for transfer
patterns is formed by dry-etching and a mold release film is formed
thereon to reflect the shape of the transfer molding base surface,
in order to obtain a mold for press-molding.
Inventors: |
Kosuga, Hiroyuki; (Tokyo,
JP) ; Yokoo, Yoshiatsu; (Hidaka-shi, JP) |
Correspondence
Address: |
NIXON & VANDERHYE, PC
1100 N GLEBE ROAD
8TH FLOOR
ARLINGTON
VA
22201-4714
US
|
Family ID: |
27311330 |
Appl. No.: |
10/659440 |
Filed: |
September 11, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10659440 |
Sep 11, 2003 |
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09667512 |
Sep 22, 2000 |
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09667512 |
Sep 22, 2000 |
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09064148 |
Apr 22, 1998 |
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6156243 |
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Current U.S.
Class: |
425/406 |
Current CPC
Class: |
C03B 2215/404 20130101;
C03B 2215/412 20130101; Y02P 40/57 20151101; B29C 33/42 20130101;
C03B 2215/413 20130101; G02B 6/3696 20130101; G02B 6/4224 20130101;
C03B 11/08 20130101; C03B 11/082 20130101; G02B 6/3652 20130101;
B29C 33/3842 20130101; G02B 6/3692 20130101; G02B 6/3636 20130101;
C03B 2215/414 20130101 |
Class at
Publication: |
425/406 |
International
Class: |
B29D 011/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 25, 1997 |
JP |
H9-108831 |
Apr 25, 1997 |
JP |
H9-108833 |
Jun 6, 1997 |
JP |
H9-149214 |
Claims
1. A mold having a transfer molding surface of a predetermined
shape and is used for press-molding a shaping material into a
optical element fixing member, wherein alignment mark-transfer
portion(s) is/are formed on the transfer molding surface in order
to obtain a press-molded article having alignment mark(s).
2. A mold according to claim 1, wherein the mold comprises a base
member and a mold release film formed on the surface of the base
member, the base member comprising (1) a hard material containing
WC or (2) a cermet containing TiN, TiC or Al.sub.2O.sub.3, and the
surface of the mold release film serves as a transfer molding
surface.
3. A mold according to claim 1, wherein the mold comprises SiC or
amorphous carbon.
4. A method of producing a mold having a transfer molding surface
of a predetermined shape and is used for press-molding a shaping
material into a optical element fixing member, wherein shaping
portion(s) for forming alignment mark transfer portion(s) is/are
formed by dry-etching on the mold material so that the alignment
mark transfer portion(s) is/are formed on the transfer molding
surface of the mold for obtaining a optical element fixing member
and having the alignment mark(s), a mold release film is formed so
that the shaping portion(s) is/are covered and that the surface of
the mold release film serves as the transfer molding surface,
thereby to obtain a mold having the alignment mark transfer
portion(s) which comprise the shaping portion(s) and the mold
release film covering the surface(s) of the shaping portion(s), the
surface of the mold release film serving as the transfer molding
surface.
5. A method of producing a mold having a transfer molding surface
of a predetermined shape and is used for press-molding a shaping
material into a optical element fixing member, wherein alignment
mark transfer portion(s) is/are formed by dry-etching on the mold
material so as to be positioned on the transfer molding surface of
the mold in order to obtain a optical element fixing member and
having the alignment mark(s).
6. A optical element fixing member, wherein alignment mark(s) for
determining a positional relationship relative to other member(s)
is/are integrally molded, and the alignment mark(s) have a surface
roughness which is different from a surface roughness on the
periphery of the alignment mark(s).
7. A optical element fixing member according to claim 6, wherein
the member comprises a glass.
8. A method of producing a mold having a transfer molding surface
constituted by a plurality of transfer patterns and is used for
press-molding a shaping material into an article of a predetermined
shape, wherein alignment mark(s) is/are formed on a mold material
by dry-etching, and the mold material is worked using the alignment
mark(s) as reference(s) in order to form the transfer molding
surface constituted by the plurality of transfer patterns.
9. A method according to claim 8, wherein a rare gas, a simple gas
of the CF type or a simple gas of the Cl type is/are used as the
etching gas(es) at the time of forming the alignment mark(s) by
dry-etching.
10. A method of producing a mold having a transfer molding surface
constituted by a plurality of transfer patterns and is used for
press-molding a shaping material into an article of a predetermined
shape, wherein alignment mark(s) is/are formed on a mold material
by dry-etching, the mold material is worked by using the alignment
mark(s) as reference(s) in order to form a transfer molding bare
surface constituted by bare transfer patterns that serve as bases
for the transfer patterns, and a mold release film is formed so as
to cover at least the transfer molding bare surface, the surface of
the mold release film serving as a transfer surface.
11. A method according to claim 10, wherein a single kind of gas or
plural kinds of gases selected from the group consisting of a rare
gas, a simple gas of the CF type and a simple gas of the Cl type
is/are used as the etching gas(es) at the time of forming the
alignment mark(s) by dry-etching.
12. A mold comprising a base member having a transfer molding bare
surface of a predetermined shape formed by dry-etching, and a mold
release film formed on the transfer molding bare surface so as to
reflect the shape of the transfer molding bare surface, the surface
of the mold release film serving as a transfer molding surface.
13. A mold according to claim 12, wherein the base member comprises
(1) a hard material containing WC, or (2) a cermet containing TiN,
TiC or Al.sub.2O.sub.3.
14. A mold according to claim 12, wherein transfer pattern(s)
corresponding to rugged pattern(s) of a diffraction element, is/are
formed on the transfer molding surface.
15. A mold having a transfer molding surface formed on the mold
material by dry-etching.
16. A mold according to claim 15, wherein the mold comprises
amorphous carbon.
17 A mold according to claim 15, wherein transfer pattern(s)
corresponding to rugged pattern(s) of a diffraction element, is/are
formed on the transfer molding surface.
18. A method of producing a mold by obtaining a base member by
forming, on the mold material by dry-etching, a transfer molding
bare surface that serves as a base for the transfer molding
surface, and forming a mold release film on the transfer molding
bare surface so as to reflect the shape of the transfer molding
bare surface, the surface of the mold release film serving as a
transfer molding surface.
19. A method according to claim 18, wherein, in obtaining a base
member by forming a transfer molding bare surface on a mold
material by dry-etching by using, as the mold material, either (1)
a hard material containing WC or (2) a cermet containing TiN, TiC
or Al.sub.2O.sub.3, use is made, as etching gas(es), of a single
kind of gas or plural kinds of gas(es) selected from the group
consisting of a rare gas, a simple gas of the carbon fluoride type
and a simple gas of the chlorine type.
20. A method according to claim 18, wherein there is formed a
transfer molding base surface having rugged pattern(s)
corresponding to rugged pattern(s) of the diffraction element.
21. A method of producing a mold by forming a transfer molding
surface on a mold material by dry-etching.
22. A method according to claim 21, wherein, in forming a transfer
molding surface on a mold material by dry-etching by using
amorphous carbon as the mold material, use is made of a rare gas, a
simple gas of the carbon fluoride type or a simple gas of the
chlorine type as etching gas(es).
23. A method according to claim 21, wherein there is formed a
transfer molding surface having transfer pattern(s) corresponding
to rugged pattern(s) of a diffraction element.
24. A method of producing a diffraction element of a glass relying
upon the press-molding by using a set of molds including the mold
of claim 12 or claim 15 as an upper mold or as a lower mold.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a mold for obtaining a
desired molded article by press-molding, to a method of producing
the mold, and to a molded article obtained by using the mold.
DESCRIPTION OF THE PRIOR ART
[0002] Press-molding is a technology which makes it possible to
produce molded articles having a predetermined shape maintaining a
high productivity once a mold used for the press-molding is
fabricated. At present, therefore, the molded articles of a variety
of shapes have been produced by press-molding. Moreover, the
press-molding makes it possible to mass-produce the molded articles
maintaining high accuracy. Nowadays, therefore, products that
require high degree of accuracy, such as optical element fixing
member and diffraction elements, have been produced by
press-molding.
[0003] Here, the "optical element fixing members" referred to as in
this specification stand for members that are used for fixing or
mounting a predetermined number of elements required for the
transmission and reception of light or for the relay of light, as
represented by optical elements such as micro-lens, polarizer
plate, diffraction grating, wave plate, filter, optical amplifier,
optical waveguide and optical fiber, as well as light-emitting
elements such as semiconductor laser and light-emitting diode, and
light-receiving elements such as photodiode, etc. (hereinafter,
these elements are referred to as "optical elements"). In the
optical element fixing member are, usually, formed ruggedness of a
predetermined shape for fixing or mounting the optical elements.
Depending upon the applications, however, the members are produced
in the shape of a flat plate without ruggedness. Furthermore, the
"diffraction elements"-referred to as above stand for optical
elements used for dispersing, deflecting or converging light by
utilizing the diffraction of light, such as diffraction grating and
zone plate.
[0004] For the transmission or reception of light or for the relay
of light, it is necessary to optically connect desired optical
elements together (hereinafter referred to as "optical
interconnection") on an optical element fixing member or between
the two optical element fixing members. To accomplish the optical
interconnection, the optical elements must be aligned highly
accurately.
[0005] In optically connecting the quartz-based single-mode optical
fibers together, for example, the alignment must be accomplished as
highly accurately as that the amount of deviation between the
optical axes is within about .+-.1 .mu.m from the standpoint of
decreasing the connection loss (down to, for example, 0.1 dB or
less) that is caused by a deviation of the optical axes in the
optically connected portion.
[0006] So far, an active alignment by using a precision stage has
been employed for the optical interconnection of the optical
elements on the optical element fixing member and for the optical
interconnection of the optical elements between the optical element
fixing members to which the optical elements are fixed or on which
the optical elements are mounted. In optically connecting the
optical fibers together relying upon the active alignment, light
that is going out from one optical fiber is permitted to fall on
the other optical fiber, and the precision stage is driven over a
wide range so that the amount of incident light becomes a maximum,
thereby to accomplish the positioning between the two.
[0007] However, the optical interconnection based on the active
alignment requires an extended period of time since the precision
stage must be driven over a wide range as described above.
Moreover, the automated operation causes the structure of the
device to become complex, which makes it difficult to realize a
device for accomplishing the active alignment maintaining a desired
accuracy.
[0008] The optical interconnection of the optical elements requires
a high degree of aligning accuracy as described above. In fixing or
mounting the optical element(s) on the optical element fixing
member, therefore, it is desired that the optical element(s) is/are
fixed or mounted highly accurately. In order to highly accurately
secure or mount the optical element(s) on the optical element
fixing member, furthermore, it becomes necessary to highly
accurately mold the optical element fixing member.
[0009] Under the above-mentioned circumstances, the optical element
fixing member have nowadays been produced by press-molding. In
order to obtain products of a predetermined shape by press-molding,
first, a mold of the predetermined shape must be fabricated.
Fabricating the mold relying upon the conventional method, however,
involves difficulties as described below.
[0010] That is, many optical element fixing members have a
ruggedness of a predetermined shape. To obtain such an optical
element fixing member by press-molding, it becomes necessary to use
a mold having a highly accurately formed transfer molding surface
constituted by a plurality of transfer patterns. To obtain the mold
having a highly accurately formed transfer molding surface
constituted by the plurality of transfer patterns, it has
heretofore been attempted to form, in advance, a surface on a mold
material that will become a side surface of the mold and to machine
the mold material using a machine such as grinder by utilizing the
above side surface as a reference surface, thereby to form the
transfer molding surface constituted by the plurality of transfer
patterns. At the time of forming the surface that becomes the side
surface of the mold, however, it is difficult to prevent the
occurrence of pitching on this surface. Occurrence of pitching
makes it difficult to correctly specify the position of the
surface. It is further desired to eliminate the breakage from the
standpoint of improving the durability of the mold and improving
the productivity. For this purpose, it is often done to form on the
mold material the side surface of the mold followed by chamfering
and, then, to form the transfer molding surface. After the
chamfering, however, it becomes difficult to correctly specify the
position of the above-mentioned surface (which becomes the side
surface of the mold).
[0011] On account of these reasons, the conventional method in
which a surface to be become the side surface of the mold is,
first, formed on the mold material, and the transfer molding
surface is formed by machining by using this surface as a reference
surface, involves too many difficulties in obtaining a mold having
highly precise transfer molding surfaces constituted by the
plurality of transfer patterns.
[0012] On the other hand, the diffraction elements have heretofore
been produced by highly accurately forming a fine pattern of a
desired shape on the material relying on a mechanical ruling
method, a two-beam interference method or an etching method, or
relying on a replica method by using the thus obtained diffraction
element as a master. In recent years, it has been attempted to
mass-produce diffraction elements made of a glass relying on the
press-molding from the standpoint of accomplishing high durability,
small change in the characteristics despite a change in the ambient
temperature, and low cost.
[0013] As the molds for obtaining the glass diffraction elements by
press-molding, there have been known the one in which a transfer
pattern is formed by grinding the desired surface of the mold
material into a predetermined shape, as well as the following molds
(a) and (b).
[0014] (a) A mold in which a transfer pattern is formed by
polishing a desired surface of a base member to a mirror surface,
forming a desired thin film on the mirror surface, and patterning
the surface (surface layer) of the thin film into a predetermined
shape (see Japanese Patent Laid-Open (Kokai) Nos. Sho
64-52620(1989) and Hei 3-242333(1991) and Japanese Patent
Publication (Kokoku) No. Hei 8-23602(1996)).
[0015] (b) A mold in which a desired thin film is formed on a
desired surface of a base member directly or via an intermediate
layer, the thin film is patterned into a predetermined shape, and a
transfer pattern is formed by the patterned thin film and by the
surface of the base member that is exposed due to the patterning or
by the surface of the intermediate layer (see Japanese Patent
Laid-Open (Kokai) No. Hei 4-260621(1992)).
[0016] When the transfer pattern is formed by patterning the thin
film on the base member into a predetermined shape as in the molds
(a) and (b), the transfer pattern can be formed in a mold
maintaining a higher degree of freedom of the its configuration
than when the transfer pattern is formed by grinding a desired
surface of the mold material and, besides, a highly precise
transfer pattern can be easily obtained. However, these molds have
a defect in that the transfer pattern itself has a shorter life
than that of the mold in which the transfer pattern is formed on
the mold material.
SUMMARY OF THE INVENTION
[0017] The present invention was accomplished in order to overcome
the above-mentioned difficulties inherent in the prior art, and it
is a first object of the present invention to provide a mold
capable of producing, by press-molding, an optical element fixing
member, which makes it possible, within short periods of time, to
optically connect together the optical elements that are to be
fixed or mounted, or to optically connect together the optical
elements between the optical element fixing members to which the
optical elements are fixed or on which the optical elements are
mounted, to provide a method of producing the mold and to provide
an optical element fixing member.
[0018] A second object of the present invention is to provide a
method of easily producing a mold for press-molding having a highly
precise transfer molding surface constituted by a plurality of
transfer patterns.
[0019] A third object of the present invention is to provide a mold
which capable of easily obtaining the one for press-molding having
transfer patterns of a predetermined shape maintaining a high
accuracy and featuring an extended life of the transfer patterns,
and a method of producing the mold.
[0020] A fourth object of the present invention is to provide a
method of producing a diffraction element of a glass at a low
cost.
[0021] In order to accomplish the above-mentioned first object, the
present invention deals with a mold having a transfer molding
surface of a predetermined shape and is used for press-molding a
shaping material to be molded into an optical element fixing
member, wherein alignment mark-transfer portion(s) is/are formed on
the transfer molding surface in order to obtain a molded article
having alignment mark(s) (this mold is hereinafter referred to as
"mold A").
[0022] In order to accomplish the above-mentioned first object,
furthermore, the present invention deals with a method of producing
a mold having a transfer molding surface of a predetermined shape
and is used for press-molding a shaping material to be molded into
an optical element fixing member, wherein shaping portion(s) for
forming alignment mark transfer portion(s) is/are formed by
dry-etching on the material of the mold so that said alignment mark
transfer portion(s) is/are formed on the transfer molding surface
of said mold for obtaining an optical element fixing member and
having said alignment mark(s), a mold release film is formed so
that said shaping portion(s) is/are covered and that the surface of
said mold release film serves as said transfer molding surface,
thereby to obtain a mold having said alignment mark transfer
portion(s) which comprise said shaping portion(s) and said mold
release film covering the surface(s) of said shaping portion(s),
the surface of said mold release film serving as said transfer
molding surface (this method is hereinafter referred to as "method
aI").
[0023] In order to accomplish the above-mentioned first object, the
present invention deals with another method of producing a mold
having a transfer molding surface of a predetermined shape and is
used for press-molding a shaping material to be molded into an
optical element fixing member, wherein alignment mark transfer
portion(s) is/are formed by dry-etching on the mold material so as
to be positioned on the transfer molding surface of said mold in
order to obtain an optical element fixing member and having said
alignment mark(s) (this method is hereinafter referred to as
"method aII").
[0024] In order to accomplish the above-mentioned first object, the
present invention deals with an optical element fixing member,
wherein alignment mark(s) for determining a positional relationship
relative to other members is/are integrally molded, and said
alignment mark(s) have a surface roughness which is different from
a surface roughness on the periphery of the alignment mark(s).
[0025] In order to accomplish the above-mentioned second object,
the present invention deals with a method of producing a mold
having a transfer molding surface constituted by a plurality of
transfer patterns and is used for press-molding a shaping material
to be molded into an article of a predetermined shape, wherein
alignment mark(s) is/are formed on the mold material by
dry-etching, and said mold material is worked using said alignment
mark(s) as a reference in order to form said transfer molding
surface constituted by said plurality of transfer patterns (this
method is hereinafter referred to as "method bI").
[0026] In order to accomplish the above-mentioned second object,
furthermore, the present invention deals with another method of
producing a mold having a transfer molding surface constituted by a
plurality of transfer patterns and is used for press-molding a
shaping material to be molded into an article of a predetermined
shape, wherein alignment mark(s) is/are formed on the mold material
by dry-etching, said mold material is worked using said alignment
mark(s) as a reference in order to form a transfer molding bare
surface constituted by bare transfer patterns which serve as bases
for said transfer patterns, and a mold release film is formed so as
to cover at least said transfer molding bare surface, the surface
of said mold release film serving as the transfer molding surface
(this method is hereinafter referred to as "method bII").
[0027] In order to accomplish the above-mentioned third object, the
present invention deals with a mold comprising a base member having
a transfer molding bare surface of a predetermined shape formed by
dry-etching, and a mold release film formed on said transfer
molding bare surface so as to reflex the shape of said transfer
molding bare surface, the surface of said mold release film serving
as a transfer molding surface (this mold is hereinafter referred to
as "mold CI").
[0028] In order to accomplish the above-mentioned third object,
furthermore, the present invention deals with a mold having a
transfer molding surface formed on the mold material by dry-etching
(this mold is hereinafter referred to as "mold CII").
[0029] In order to accomplish the above-mentioned third object, the
present invention provides a method of producing a mold by
obtaining a base member by forming, on the mold material by
dry-etching, a transfer molding bare surface that serves as a base
for the transfer molding surface, and forming a mold release film
on said transfer molding bare surface so as to reflect the shape of
said transfer molding bare surface, the surface of said mold
release film serving as a transfer molding surface (this method is
hereinafter referred to as "method cI").
[0030] In order to accomplish the above-mentioned third object,
furthermore, the present invention is concerned with another method
of producing a mold by forming a transfer molding surface on the
mold material by dry-etching (this method is hereinafter referred
to as "method cII").
[0031] Moreover, in order to accomplish the above-mentioned fourth
object, the present invention deals a method of producing a
diffraction element, wherein a glass diffraction element is
obtained relying upon the press-molding by using a set of molds
including the mold CI or CII as an upper mold or as a lower
mold.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] FIG. 1 is a sectional view schematically illustrating the
steps for forming shaping portions for alignment mark transfer
portions on a mold material of a first mold according to Example 1,
wherein FIG. 1(a) is a sectional view schematically illustrating
the mold material after having formed a resist film that is a
material of resist pattern for dry-etching, FIG. 1(b) is a
sectional view schematically illustrating the mold material after
the resist pattern is formed, and FIG. 1(c) is a sectional view
schematically illustrating the mold material after shaping portions
are formed for forming the alignment mark transfer portions;
[0033] FIG. 2(a) is a plan view schematically illustrating the base
member of the first mold produced in Example 1 as viewed from the
side where the shaping portions are formed for forming the
alignment mark transfer portions, and FIG. 2(b) is a sectional view
schematically illustrating the base member;
[0034] FIG. 3(a) is a plan view schematically illustrating the
first mold produced in Example 1 as viewed from the side where the
alignment mark transfer portions are formed, and FIG. 3(b) is a
sectional view schematically illustrating the first mold;
[0035] FIG. 4 is a plan view schematically illustrating an optical
element fixing member produced in Example 4 as viewed from the side
where the alignment marks are formed.
[0036] FIG. 5 is a plan view schematically illustrating the optical
element fixing member produced in Example 4 as viewed from the side
where the alignment marks are formed;
[0037] FIG. 6 is a perspective view schematically illustrating the
optical element fixing members produced in Example 6;
[0038] FIG. 7(a) is a plan view schematically illustrating a mold
produced in Example 8 as viewed from the side where the alignment
marks are formed, and FIG. 7(b) is a sectional view schematically
illustrating the mold;
[0039] FIG. 8 is a sectional view schematically illustrating the
steps for producing a first mold according to Example 12, wherein
FIG. 8(a) is a sectional view schematically illustrating the mold
material after having formed a resist film that is a material of
resist pattern for dry-etching, FIG. 8(b) is a sectional view
schematically illustrating the mold material after the resist
pattern is formed, FIG. 8(c) is a sectional view schematically
illustrating the mold material (base member) on which a transfer
molding bare surface is formed, and FIG. 8(d) is a sectional view
schematically illustrating a first mold that is produced;
[0040] FIG. 9 is a plan view schematically illustrating a
diffraction grating produced in Example 12; and
[0041] FIG. 10 is a plan view schematically illustrating a zone
plate produced in Example 13.
DETAILED DESCRIPTION OF THE INVENTION
[0042] Described below in detail are aspects for carrying out the
present invention.
[0043] First, the mold A of the invention will be described. As
described earlier, the mold A has a transfer molding surface of a
predetermined shape and is used for press-molding a shaping
material into an optical element fixing member of a predetermined
shape.
[0044] The optical element fixing member can be made of a glass, a
resin or the like material. Therefore, the material of the mold A
can be suitably changed depending upon the member that is to be
obtained for fixing optical element(s) or, in other words,
depending upon the temperature for press-molding, pressure for
press-molding, etc.
[0045] It is desired that the optical element fixing member is made
of a glass from the standpoint of obtaining, by press-molding, the
optical element fixing member, which permits the dimensional
accuracy and form accuracy to change little relative to a change in
the ambient temperature and which exhibits a small difference in
the thermal expansion from the optical element(s) that is/are to be
fixed or mounted. It is particularly desired to use a glass which
contains SiO.sub.2, B.sub.2O.sub.3 and no as glass components.
Concrete examples of the glass include the following (1) to
(4).
[0046] (1) A glass containing, as glass components, 1 to 30% by
weight of SiO.sub.2, 15 to 40% by weight of B.sub.2O.sub.3, 40 to
60% by weight of ZnO (but 40% by weight is not included), 0 to 15%
by weight of MgO, 0 to 10% by weight of CaO, 0 to 10% by weight of
SrO, 0 to 10% by weight of BaO, 0 to 20% by weight of Pbo, and 0 to
10% by weight of Al.sub.2O.sub.3 (but 0% by weight is not
included), the sum of ZnO, MgO, CaO, SrO, BaO and PbO being 40 to
60% by weight (but 40% by weight is not included), and the sum of
the glass components not being smaller than 75% by weight (this
glass is hereinafter referred to as "first glass").
[0047] (2) A glass comprising the above first glass and 0 to 10% by
weight of GeO.sub.2 (but the sum of SiO.sub.2 and GeO.sub.2 is from
3 to 30% by weight), 0 to 20% by weight of La.sub.2O.sub.3, 0 to
10% by weight of Y.sub.2O.sub.3, 0 to 10% by weight of
Gd.sub.2O.sub.3 (but the sum of La.sub.2O.sub.3, Y.sub.2O.sub.3 and
Gd.sub.2O.sub.3 is from 0 to 20% by weight.), 0 to 10% by weight of
Nb.sub.2O.sub.5, 0 to 10% by weight of Ta.sub.2O.sub.5 (but the sum
of Nb.sub.2O.sub.5 and Ta.sub.2O.sub.5 is from 0 to 10% by weight),
0 to 5% by weight of ZrO.sub.2, and 0 to 3% by weight of TiO.sub.2
(this glass is hereinafter referred to as "second glass").
[0048] (3) A glass comprising the first glass or the second glass
to which are added one or more of As.sub.2O.sub.3, Sb.sub.2O.sub.3,
SnO and SnO.sub.2 as additive agent(s) in an attempt to improve
degassing and decoloring (this glass is hereinafter referred to as
"third glass").
[0049] (4) A glass comprising any one of the first glass to the
third glass to which are further added F, Bi.sub.2O.sub.3,
Yb.sub.2O.sub.3, WO.sub.3, Na.sub.2O, K.sub.2O etc. in amounts
which do not adversely affect the properties of the glass.
[0050] As the material of the mold A for obtaining, by
press-molding, the optical element fixing member made of glass,
there can be preferably used an hard material containing tungsten
carbide (WC), a cermet containing titanium nitride (TiN), titanium
carbide (TiC) or aluminum oxide (Al.sub.2O.sub.3), or those
comprising silicon carbide (Sic) or amorphous carbon. It is desired
that the cermet described above contains TiN, TiC or Al.sub.2O, in
an amount of roughly not smaller than 90% by weight.
[0051] When it is attempted to obtain the mold A for producing the
optical element fixing member made of glass by using the mold
material comprising the above-mentioned hard material or cermet, it
is desired that the predetermined surfaces of the mold material
(hereinafter the mold material is referred to as "base member")
after it is worked into a desired shape are coated with a mold
release film, so that the surfaces of the mold release film serves
as transfer molding surfaces, from the standpoint of preventing the
melt-adhesion between the mold and the shaping material (glass) to
be molded during the press-molding.
[0052] There can be used mold release films of various compositions
depending upon the material of the base member and the composition
of the shaping material. In order to prevent the melt-adhesion
between the glass shaping material and the mold, however, the mold
release film will be the one containing at least one component
selected from the group consisting of Pt, Au, Ir, Pd and Rh, or the
one comprising i-carbon. When it is attempted to obtain the mold A
for producing the optical element fixing member made of glass by
using the mold material comprising SiC or amorphous carbon, the
mold release film may be formed or may not be formed.
[0053] The mold A of the present invention has alignment mark
transfer portion(s) formed on the transfer molding surface thereof
in order to obtain a molded article having alignment mark(s). The
shape of the transfer molding surface excluding the alignment mark
transfer portion(s) can be suitably selected depending upon the use
of the optical element fixing member, that is to be obtained by
using the mold A. It is obtained, for example, as a flat surface,
as two or more flat surfaces the boundary thereof forming a step, a
combination of flat surface(s) (above described one flat surface or
above described two or more flat surfaces) and recessed portion(s)
of a predetermined shape, a combination of flat surface(s) (above
described one flat surface or above described two or more flat
surfaces) and protruded portion(s) of a predetermined shape, or a
combination of flat surface(s) (above described one flat surface or
above described two or more flat surfaces), protruded portion(s) of
a predetermined shape and recessed portion(s) of a predetermined
shape.
[0054] On the other hand, the shape of the alignment mark transfer
portion(s) as viewed on a plane is suitably selected depending upon
the shape of the alignment mark(s) that are to be formed on the
optical element fixing member. The number of the alignment mark
transfer portion(s) formed on a transfer molding surface and the
place(s) where the portion(s) is/are to be formed, are suitably
selected depending upon the use of the optical element fixing
member, that is to be obtained by using the mold, upon the shape
and number of the optical element(s) that is/are to be fixed or
mounted on the optical element fixing member, and upon the use of
the alignment mark(s) on the optical element fixing member.
[0055] The alignment mark transfer portion may be formed in a
protruded manner or in a recessed manner. When it is attempted to
obtain the optical element fixing member for highly densely fixing
or mounting the optical elements, however, it is desired that the
alignment mark(s) formed on the optical element fixing member
is/are also utilized as part of the region for fixing or mounting
the optical elements. It is therefore desired that the alignment
mark(s) is/are formed in a recessed manner so that the optical
element(s) can be stably and easily fixed or mounted covering part
or whole of the alignment mark(s). A desired member may also be
placed on the optical element fixing member so that the optical
element(s) can be fixed or mounted thereon more firmly. Even in
this case, the member can be stably and easily placed provided the
alignment mark(s) is/are formed in a recessed manner in the optical
element fixing member.
[0056] Therefore, when it is attempted to obtain a optical element
fixing member for highly densely fixing or mounting the optical
element(s) or to obtain a optical element fixing member on which
the member(s) can be placed in addition to the optical element(s),
it is desired that the alignment mark transfer portion(s) is/are
formed in a protruded manner on the mold A of the present
invention.
[0057] Usually, a plurality of optical elements are fixed or
mounted on the optical element fixing member. In order to optically
connect these optical elements on the optical element fixing member
by mechanically positioning these optical elements, it is necessary
to position these optical elements in at least the two-dimensional
directions. Moreover, even when the optical elements are optically
connected together being fixed or mounted on the optical element
fixing member by mechanically positioning the members on which the
optical elements are fixed or mounted, it becomes necessary to
position them in at least the two-dimensional directions.
[0058] It is therefore desired that the alignment mark transfer
portion(s) have two or more straight portions like an L-shape, a
crossed shape, a triangular frame shape or a rectangular frame
shape as viewed on a plane, the straight portions subtending a
predetermined angle relative to each other. The alignment mark
formed by the alignment mark transfer portion having the
above-mentioned shape, possess two or more straight portions which
are subtending a predetermined angle relative to each other. It is
therefore allowed to easily position the optical element(s) or the
optical element fixing members in the two-dimensional
directions.
[0059] When the mold A has a mold release film, the alignment mark
transfer portion(s) is/are formed by shaping portion(s) to be
coated with the mold release film and serve as the alignment mark
transfer portion(s) (the shaping portion(s) is/are formed on the
base member and are hereinafter simply referred to as "shaping
portion") and by the mold release film covering the shaping
portion(s). Or, the alignment mark transfer portion(s) is/are
formed by the mold release film. When the mold does not have the
mold release film, the alignment mark transfer portion(s) is/are
formed on the mold material.
[0060] The shaping portion(s) can be formed on the mold material
and the alignment mark transfer portion(s) can be formed on the
mold material relying upon, for example, machine work or etching.
In the case of the machine work, however, the tip of a cutting tool
does not enter into a portion where straight protruded portions
intersect each other, making it difficult to accurately form the
alignment mark transfer portion(s) or the shaping portion(s) having
intersecting portion(s). Moreover, when it is attempted to obtain
the mold A having a step in the transfer molding surface (excluding
the step between the alignment mark transfer portion and the
surrounding thereof), it is not allowed to introduce the tip of the
cutting tool for machine work near to the step in the region on the
lower side divided by the step. Therefore, limitation is imposed on
the region where the alignment mark transfer portion(s) or the
shaping portion(s) can be formed by machine work. Furthermore, it
is difficult to form, by wet etching, the highly precise alignment
mark transfer portion(s) or the shaping portion(s) on the mold
material composed of the above-mentioned hard material, cermet, SiC
or amorphous carbon.
[0061] It is therefore desired to form, by dry etching, the molding
portion(s) or the alignment mark transfer portion(s) on the mold
material and, particularly, the molding portion(s) or the alignment
mark transfer portion(s) having two or more straight portions which
are subtending a predetermined angle relative to each other. The
dry etching makes it possible to highly accurately form the shaping
portion(s) or the alignment mark transfer portion(s) of a desired
shape at any desired place.
[0062] From the standpoint of obtaining an optical element fixing
member of which the alignment mark can be easily identified by eyes
or by an image-recognizing device, it is desired that the alignment
mark has a surface roughness which is different from the surface
roughness of the periphery of the alignment mark. In the mold A,
too, therefore, it is desired that the alignment mark transfer
portion(s) have a surface roughness which is different from the
surface roughness of the transfer molding surface in the periphery
of the alignment mark transfer portion(s). By using the mold A in
which a maximum surface roughness of the alignment mark transfer
portion(s) is different by roughly more than 200 angstroms from a
maximum surface roughness on the transfer molding surface in the
periphery of the alignment mark transfer portion(s), it is allowed
to obtain, by press-molding, the optical element fixing member of
which the alignment mark(s) can be easily identified by eyes or by
an image-recognizing device even when, for example, a transparent
glass is used as a shaping material.
[0063] The mold A of the present invention described above has the
alignment mark transfer portion(s) as described above. Therefore,
the molds A of the present invention may be combined together, or
the mold A of the present invention may be combined with a
conventional mold to constitute a set of molds necessary for
press-molding (inclusive of those constituted by an upper mold and
a lower mold, or constituted by an upper mold, a lower mold and a
sleeve mold. Include a set of molds in which the lower mold or the
upper mold is a flat plate), and the shaping material is
press-molded by using the set of molds thereby to obtain an optical
element fixing member and having alignment mark(s). Here, the molds
constituting the set of molds may be made of the same material or
different materials. Moreover, the molds constituting the set of
molds may or may not have a mold release film.
[0064] The optical element fixing member will assume a variety of
shapes depending upon the applications, such as flat plate, plate
having one or more steps, etc. Therefore, the shape of the molds
(shape of the transfer molding surface of each mold) constituting
the set of molds is so selected as to obtain a optical element
fixing member of a desired shape.
[0065] The optical element fixing member obtained by press-molding
by using the mold A of the present invention has predetermined
alignment mark(s) formed thereon. When a plurality of optical
elements are to be fixed or mounted on the optical element fixing
member, therefore, the optical elements are positioned by utilizing
the alignment mark(s). Thus, the optical elements are optically
connected together relying upon the positioning only, or the
optical elements are nearly optically connected together relying
upon the positioning. Therefore, the optical interconnection can be
accomplished within a short period of time even when a highly
precise optical interconnection is carried out in a subsequent step
relying upon the active alignment. Similarly, even when the optical
elements are to be optically connected together between the optical
element fixing members on which the optical elements have been
fixed or mounted, these optical element fixing members are
positioned by utilizing the alignment marks formed on the optical
element fixing members, in order to accomplish the optical
interconnection within a short period of time.
[0066] By using the above-mentioned optical element fixing member,
therefore, the optical element(s) that is/are to be fixed or
mounted can be optically connected together or the optical elements
can be optically connected together between the optical element
fixing members on which the optical elements have been fixed or
mounted within a period of time shorter than that of when the
optical interconnection between the optical elements is
accomplished relying upon the active alignment only. Moreover, the
optical interconnection can be automatically and easily
accomplished.
[0067] The mold A of the present invention for obtaining the
optical element fixing member having the above-mentioned
advantages, can be produced by the method aI or the method aII of
the present invention that will be described below.
[0068] As described earlier, the method aI of the present invention
is to produce a mold (the above-mentioned mold A of the present
invention) having a transfer molding surface of a predetermined
shape and is used for press-molding a shaping material into an
optical element fixing member, wherein shaping portion(s) for
forming alignment mark transfer portion(s) is/are formed by
dry-etching on the mold material so that the alignment mark
transfer portion(s) is/are formed on the transfer molding surface
of the mold for obtaining an optical element fixing member and the
alignment mark(s), a mold release film is formed so that the
shaping portion(s) is/are covered and that the surface of the mold
release film serves as the transfer molding surface, thereby to
obtain a mold having the alignment mark transfer portion(s) which
comprise the shaping portion(s) and the mold release film covering
the surfaces of the shaping portion(s), the surface of the mold
release film serving as the transfer molding surface.
[0069] This method aI is to obtain the mold A in which a
predetermined surface of the mold material (base member) worked
into a desired shape is coated with the mold release film, and the
surface of the mold release film serves as the transfer molding
surface (alignment mark transfer portion(s) is/are formed on the
transfer molding surface). When the mold A for press-molding a
glass molded article (optical element fixing member) is to be
produced by the method aI, therefore, it is desired to use an hard
material or cermet (described already concerning the mold A of the
invention) as a material of the mold A. It is also allowable to use
a mold material such as SiC or amorphous carbon, as a matter of
course.
[0070] In order to form the shaping portion(s) for forming the
alignment mark transfer portion(s) on the mold material by
dry-etching, at least portion where the shaping portion(s) is/are
to be formed are formed flat on the surface of the mold material, a
resist pattern of a desired shape is formed on the flat surface,
and the dry-etching is effected by using the resist pattern as a
mask.
[0071] The shape as viewed on a plane and the number of the
alignment mark transfer portions and the portions where they are to
be formed, are suitably selected depending upon the use of the
optical element fixing member that is obtained by using the mold A
as described already in the description of the mold A of the
invention. Therefore, such requirements are suitably selected
depending upon the use of the optical element fixing member that is
obtained by using the mold A.
[0072] Similarly, furthermore, the shape of the portion
(hereinafter referred to as "peripheral portion") on the transfer
molding surface other than the alignment mark transfer portion(s),
is suitably selected depending upon the use of the optical element
fixing member obtained by using the mold A. Therefore, the shape of
the surface of the mold material of the peripheral portion on where
the mold release film will be formed, is suitably selected
depending upon the use of the optical element fixing member that is
obtained by using the mold A.
[0073] In obtaining the mold A according to the method aI,
therefore, the portion which will become the peripheral portion on
the surface of the mold material is worked into a desired shape in
advance to obtain a base member of the desired shape in addition to
forming the shaping portion(s) for forming the alignment mark
transfer portion(s) by dry-etching prior to forming the mold
release film. The shaping portion(s) may be formed by dry-etching
simultaneously with, or separately from, the portion that will
become the peripheral portion on the surface of the mold material.
On the surface of the mold material, the portion which will become
the peripheral portion can be formed by dry-etching or by machine
work depending upon the shape thereof, or can be formed by
dry-etching and machine work in combination.
[0074] It is desired that the alignment mark transfer portion(s)
is/are formed as accurately as possible. For this purpose, it is
desired to form the shaping portion(s) for forming the alignment
mark transfer portion(s) as accurately as possible. From the
standpoint of forming the shaping portion(s) as accurately as
possible, the dry-etching conditions are suitably selected
depending upon the mold material. When the mold material is the
above-mentioned hard material or cermet, it is desired to use, as a
dry-etching gas, one or more kinds of gases selected from the group
consisting of a rare gas (Ar gas or the like gas), a simple gas of
the carbon fluoride type (CF.sub.4 gas or the like gas) and a
simple gas of the chlorine type (Cl.sub.2 gas or the like gas).
When the mold material comprises SiC or amorphous carbon,
furthermore, it is desired to use the above-mentioned rare gas,
simple gas of the carbon fluoride type or simple gas of the
chlorine type as the dry-etching gas.
[0075] As the mold release film formed on the base member so as to
cover the shaping portion(s) formed by dry-etching and so as to
serve as the transfer molding surface, there can be used those of a
variety of compositions depending upon the base member and the
shaping material as described earlier concerning the mold A of the
invention. The mold release film can be formed by, for example,
sputtering method, ion-plating method or CVD method.
[0076] From the standpoint of obtaining an optical element fixing
member which enables the alignment mark(s) to be easily identified
by eyes or an image-recognizing device, it is desired that the
alignment mark transfer portion(s) have a surface roughness
different from the surface roughness on the transfer molding
surface in the periphery of the alignment mark transfer portion(s)
as described above. In the mold A produced by the method aI, the
surface of the mold release film serves as the transfer molding
surface. The surface roughness of the mold release film changes
depending upon the conditions for forming the mold release film,
surface roughness on the surface of the mold material on where the
mold release film will be formed, thickness of the mold release
film, etc.
[0077] Therefore, when it is attempted to obtain, by the method aI,
the mold in which the alignment mark transfer portion(s) have a
surface roughness different from a surface roughness on the
transfer molding surface (peripheral portion) on the periphery of
the alignment mark transfer portion(s), it is recommended to
suitably select the conditions for forming the mold release film,
surface roughness on the surface of the mold material on where the
mold release film will be molded, and thickness of the mold release
film. In practice, however, it is desired that the mold release
film has a thickness which is not less than about 0.03 .mu.m at the
smallest.
[0078] According to the above-mentioned method aI of the present
invention, the shaping portion(s) for forming the alignment mark
transfer portion(s) is/are formed by dry-etching. Therefore, even
when the mold is made of the hard material, cermet, silicon carbide
(SiC) or amorphous carbon, it is allowed to form at desired
place(s) the shaping portion(s) (for forming alignment mark
transfer portion(s)) maintaining a accuracy higher than that
accomplished by the machine work or wet-etching. It is thus made
possible to obtain a mold A capable of forming an optical element
fixing member and having highly accurately formed alignment
mark(s).
[0079] The method aII of the invention will now be described.
[0080] The method aII of the present invention is for producing a
mold having a transfer molding surface of a predetermined shape and
is used for press-molding a shaping material into an optical
element fixing member, wherein alignment mark transfer portion(s)
is/are formed by dry etching on the mold material so as to be
positioned on the transfer molding surface of the mold in order to
obtain an optical element fixing member and having the alignment
mark(s).
[0081] The method aII is to obtain a desired mold by forming the
alignment mark transfer portion(s) on the mold material. When it is
attempted to produce the mold A for press-molding a glass molded
article (optical element fixing member) by the method aII, it is
desired to use SiC or amorphous carbon as a material for producing
the mold A. It is also allowable to use the above-mentioned hard
material or cermet as a material of the mold.
[0082] The alignment mark transfer portion(s) can be formed on the
mold material by dry-etching in the same manner as that of forming
"shaping portion(s) for forming the alignment mark transfer
portion(s)" by the above-mentioned method aI.
[0083] The alignment mark transfer portion(s) may be so formed as
will be positioned on the transfer molding surface of the mold A.
As described already concerning the mold A of the invention, the
shape as viewed on a plane and the number of the alignment mark
transfer portion(s), place(s) where the portion(s) is/are to be
formed, and the shape of the transfer molding surface other than
the alignment mark transfer portion(s), are suitably selected
depending upon the use of the optical element fixing member that is
obtained by using the mold A.
[0084] Accordingly, the alignment mark transfer portion(s) and the
transfer molding surface other than the alignment mark transfer
portion(s) may be formed by dry-etching either simultaneously or
separately. The transfer molding surface other than the alignment
mark transfer portion(s) can be formed depending upon its shape by
either dry-etching or machine work, or by dry-etching and machine
work in combination.
[0085] It is desired that the alignment mark transfer portion(s)
is/are formed as accurately as possible. For this purpose, the
etching conditions are suitably selected depending upon the
material of the mold.
[0086] From the standpoint of obtaining an optical element fixing
member which enables the alignment mark to be easily identified by
eyes or by an image-recognizing device, it is desired that the
alignment mark transfer portion have a surface roughness different
from a surface roughness on the transfer molding surface in the
periphery of the alignment mark transfer portions as described
above. In order to obtain such a mold A, therefore, it is desired
to adjust, in advance, the surface roughness of the place(s) where
at least the alignment mark transfer portion(s) is/are to be formed
on the surface of the mold material while taking into consideration
the dry-etching conditions at the time of forming the alignment
mark transfer portion(s), material of the mold, and method of
forming the transfer molding surface other than the alignment mark
transfer portion(s).
[0087] According to the above-mentioned method aII of the present
invention, the alignment mark(s) is/are formed by dry-etching.
Therefore, even when the mold is made of the hard material, cermet,
silicon carbide (SiC) or amorphous carbon, it is allowed to form
alignment mark(s) on desired place(s) maintaining accuracy higher
than that accomplished by the machine work or wet-etching as
described already concerning the mold A of the present invention.
It is thus made possible to obtain the mold A capable of producing
an optical element fixing member and having alignment mark(s)
maintaining a high accuracy.
[0088] Next, described below is the optical element fixing member
of the present invention.
[0089] As described earlier, the optical element fixing member of
the present invention is a molded article oh which are integrally
molded alignment mark(s) for determining a positional relationship
relative to other members, and has a feature in that the alignment
mark(s) have a surface roughness different from a surface roughness
on the periphery of the alignment mark(s).
[0090] The shape of the alignment mark(s) as viewed on a plane can
be suitably selected depending upon the use, and the number of the
alignment mark and place where the alignment mark is to be formed
can be suitably selected depending upon the use of the optical
element fixing member, and the shape and the number of the optical
element(s) that is/are to be fixed or mounted on the optical
element fixing member or on the use of the alignment mark(s) molded
on the optical element fixing member. The alignment mark(s) may be
formed in a protruded manner or in a recessed manner. As described
already concerning the mold A of the present invention, however, it
is desired that the alignment mark(s) is/are formed in a recessed
manner from the standpoint of obtaining the optical element fixing
member for fixing or mounting the optical element(s) highly densely
or of obtaining the optical element fixing member, which permits
member(s) other than the optical element(s) to be placed
thereon.
[0091] From the standpoint of optically connecting the optical
elements that are to be fixed or mounted, or of optically
connecting the optical elements between the optical element fixing
members on which the optical elements have been fixed or mounted,
it is desired that the alignment mark has two or more straight
portions such as of an L-shape, a crossed shape, a triangular frame
shape or a rectangular frame shape as viewed on a plane, the
straight portions subtending a predetermined angle.
[0092] Though there is no particular limitation on the surface
roughness of the alignment mark, it is desired that a maximum
surface roughness of the alignment mark is different by roughly
more than 200 angstroms from a maximum surface roughness of the
periphery of the alignment mark, so that the alignment mark can be
easily identified by eyes or by an image-recognizing device.
[0093] The optical element fixing member of the present invention
having the above-mentioned alignment mark(s) is made of an
inorganic material or an organic material that can be press-molded,
such as glass, resin or the like. As described already concerning
the mold A of the present invention, it is desired that the optical
element fixing member is made of a glass so that it exhibits a
small change in the dimensional accuracy and form accuracy relative
to a change in the ambient temperature and that it exhibits a small
difference in the thermal expansion from the optical element(s)
that are to be fixed or mounted. When the optical element fixing
member of the present invention is made of a transparent material,
furthermore, the alignment mark(s) formed on the optical element
fixing member can be identified from various directions, offering
advantages (A) and (B) as described below compared with when it is
made of an opaque material or a translucent material.
[0094] (A) The opaque optical element(s) can be fixed or mounted so
as to cover the alignment mark(s) while identifying the alignment
mark(s) from the side surface or back surface (the surface of the
side opposite to the surface on where the optical element(s) is/are
to be fixed or mounted, the same holds hereinafter) of the optical
element fixing member. Or, in other words, the alignment mark(s)
can be utilized as part of the region for fixing or mounting the
opaque optical element(s), making it possible to highly densely and
easily secure or mount the optical elements.
[0095] (B) The alignment mark(s) can be identified from the side
surface or back surface of the optical element fixing member even
when another member is fixed or mounted thereon in order to further
firmly secure the optical element(s). Therefore, despite the
optical element(s) and the above-mentioned another member are made
of opaque materials, the alignment marks formed in the optical
element fixing members can be utilized at the time of optically
connecting the desired optical elements between the optical element
fixing member and another optical element fixing member (on which
the optical element(s) have been fixed or mounted).
[0096] The above-mentioned optical element fixing member of the
present invention has alignment mark(s) as described above. When a
plurality of optical elements are to be fixed or mounted on the
optical element fixing member, therefore, the optical elements are
positioned by utilizing the above-mentioned alignment mark(s),
making it possible to optically connect the optical elements
relying upon the positioning only or to nearly optically connect
the optical elements relying upon the positioning. Therefore, the
optical interconnection can be accomplished within a short period
of time even when a more precise optical interconnection is
effected in a subsequent step relying on the active alignment.
Similarly, even when the optical elements are to be optically
connected between the optical element fixing members on which the
optical elements have been fixed or mounted, the optical element
fixing members are positioned by utilizing the alignment marks
formed in the optical element fixing members, in order to shorten
the time needed for the optical interconnection.
[0097] That is, by using an optical element fixing member of the
present invention, the optical elements to be fixed or mounted can
be optically connected, or the optical elements can be optically
connected between the optical element fixing members on which the
optical elements have been fixed or mounted, requiring a period of
time shorter than that of when the optical interconnection is
accomplished relying upon the active alignment only. Moreover, the
optical interconnection can be automatically and easily
accomplished. Furthermore, the optical element fixing member of the
present invention can be obtained in large quantity and cheaply
through press-molding that will be described later.
[0098] The shape of the optical element fixing member of the
present invention as a whole can be suitably selected depending
upon its use, such as flat plate or a plate having one or more
steps (excluding a step between the alignment mark(s) and the
periphery thereof).
[0099] The optical element fixing member of the present invention
having the above-mentioned advantages can be obtained by
press-molding by using a mold exemplified as one of the preferred
molds A of the present invention, i.e., by using a set of molds
(including the one constituted by an upper mold and a lower mold,
the one constituted by an upper mold, a lower mold and a sleeve
mold, and the one in which a lower mold or an upper mold is a flat
plate) which is a combination of the mold A in which the surface
roughness of the alignment mark transfer portion(s) is different
from the surface roughness on the transfer molding surface in the
periphery of the alignment mark transfer portion(s) and other
mold(s) (mold A of the invention or a conventional mold).
[0100] In effecting the press-molding, it is desired to use a
shaping material (shaping preform) to be molded having a shape, as
viewed on a plane, which is close to the shape of the optical
element fixing member as viewed on a plane. As the material to be
molded, there is used any desired inorganic material or organic
material that can be press-molded, such as glass, resin or the
like. It is desired to use a glass as the material to be molded
from the standpoint of obtaining an optical element fixing member,
that exhibits a small difference in the thermal expansion from the
optical element(s) that is/are to be fixed or mounted. As the glass
that makes it possible to obtain a press-molded article and to
obtain an optical element fixing member having the above-mentioned
properties, there can be exemplified those described earlier
concerning the mold A of the invention.
[0101] Described below next is the method bI of the present
invention.
[0102] As described above, the method bI of the present invention
is for easily producing a mold for press-molding having a highly
accurately formed transfer molding surface constituted by a
plurality of transfer patterns. According to this method bI, first,
alignment mark(s) are formed on the mold material by
dry-etching.
[0103] The material of the mold can be suitably selected depending
upon the material of the article that is to be press-molded or, in
other words, depending upon the press-molding temperature and the
press-molding pressure. As the material of the article that is to
be press-molded (shaping material), there have been known a glass,
a resin and the like. It is, however, desired to use a glass as a
shaping material for molding the optical element fixing member from
the standpoint of obtaining, by press-molding, the optical element
fixing member exhibiting a small change in the dimensional accuracy
and in the form accuracy relative to a change in the ambient
temperature and a small difference in the thermal expansion from
the optical element(s) that is/are to be fixed or mounted.
[0104] As the mold material for obtaining, by press-molding, a
optical element fixing member made of glass, there can be
preferably used the hard material, cermet, silicon carbide (SiC) or
amorphous carbon that were exemplified above as the materials of
the mold A of the present invention.
[0105] Here, the method bI is for obtaining a desired mold while
forming a transfer molding surface on the mold material. When it is
attempted to produce a mold for obtaining a molded article of glass
relying upon the method bI, therefore, it is desired to use SiC or
amorphous carbon as the mold material.
[0106] The alignment mark(s) can be formed on the mold material by
dry-etching in the same manner as the formation of the "shaping
portion(s) for forming the alignment mark transfer portion(s)" by
the above-mentioned method aI or in the same manner as the
formation of the "alignment mark transfer portion(s)" by the
above-mentioned method aII. In this case, it is desired that the
alignment mark(s) is/are formed as accurately as possible. For this
purpose, the dry-etching conditions are suitably selected depending
upon the material of the mold.
[0107] From the standpoint of easily identifying the alignment
mark(s) by eyes or an image-recognizing device, furthermore, it is
desired that the surface roughness of the alignment mark(s) is set
to be different from the surface roughness on the periphery of the
alignment mark(s) in the same manner as done in the above-mentioned
methods aI and aII.
[0108] The shape of the alignment mark(s) can be suitably selected
as viewed on a plane, and the alignment mark(s) may be formed in a
protruded manner or in a recessed manner. Moreover, the number of
the alignment mark(s) and the place(s) where the alignment mark(s)
is/are to be formed are suitably selected depending upon the shape
of the transfer patterns to be formed on the transfer molding
surface in the mold or the upon the use of the mold.
[0109] For example, when it is desired to obtain a mold in which a
plurality of transfer patterns of a recessed shape or a protruded
shape are highly accurately arranged in the two-dimensional
directions, it is desired that the alignment mark(s) have two or
more straight portions like that of an L-shape, a crossed shape, a
triangular frame shape or a rectangular frame shape as viewed on a
plane, and that these straight portions are formed subtending a
predetermined angle. By using the alignment mark(s) having the
above-mentioned shape, it becomes easy to form a transfer molding
surface on which a plurality of transfer patterns of a recessed
shape or a protruded shape are highly accurately arranged in the
two-dimensional directions.
[0110] Upon so forming the alignment mark(s) as to be located on
the transfer molding surface, then, the alignment mark(s) work as
"shaping portion(s) for forming the alignment mark transfer
portion(s)" referred to in the mold A of the present invention. It
is therefore allowed to obtain a molded article having alignment
mark(s) of a shape corresponding to the above-mentioned alignment
mark(s), e.g., to obtain the above-mentioned optical element fixing
member of the present invention.
[0111] In the method bI of the present invention, the alignment
mark(s) is/are formed by dry-etching and, then, the mold material
is worked with the alignment mark(s) as a reference thereby to form
the transfer molding surface constituted by a plurality of transfer
patterns.
[0112] Each shape of the transfer patterns is suitably selected
depending upon the shape of the molded article that is to be
obtained by using the mold produced according to the method bI, and
may have a plane shape, a predetermined recessed shape or a
predetermined protruded shape. Similarly, the combination of
transfer patterns for constituting the transfer molding surface can
be suitably selected depending upon the shape of the molded article
that is to be obtained by using the mold produced by the method bI.
Examples include a combination of two or more flat surfaces in
which the boundary portion is forming a step, a combination of flat
surface(s) (one flat surface or above described two or more flat
surfaces) and predetermined recessed shape(s), a combination of
flat surface(s) (one flat surface or above described two or more
flat surfaces) and predetermined protruded shape(s), and a
combination of flat surface(s) (one flat surface or above described
two or more flat surfaces), predetermined protruded shape(s) and
predetermined recessed shape(s).
[0113] When the an alignment mark is so formed as will be located
on the transfer molding surface, "the transfer molding surface
constituted by a plurality of transfer patterns" referred to by the
method bI of the present invention stands for the one having a
total of three or more transfer patterns inclusive of the alignment
mark.
[0114] The alignment mark(s) that is/are to be located on the
transfer molding surface, is/are formed by dry-etching as described
above. Here, however, no particular limitation is imposed on the
method of forming other transfer patterns; i.e., etching method
(dry-etching method or wet-etching method), grinding method, a
combination of etching method and grinding method or the like
method can be suitably selected depending upon the shape of the
other transfer patterns. Even when the alignment mark(s) is/are not
positioned on the transfer molding surface, no particular
limitation is imposed on the method of forming the transfer
patterns; i.e., etching method (dry-etching method or wet-etching
method), grinding method, a combination of etching method and
grinding method or the like method can be suitably selected
depending upon the shape of the transfer patterns.
[0115] When the above-mentioned alignment mark(s) is/are to be
located on the transfer molding surface, other transfer patterns
may all be formed at the time of forming the alignment mark(s), or
some of the other transfer patterns may be formed at the time of
forming the alignment mark(s) and the remainder of the transfer
pattern(s) may be formed after the alignment mark(s) have been
formed, or other transfer patterns may all be formed after the
alignment mark(s) have been formed, depending upon the shape of the
transfer patterns other than the alignment marks
[0116] According to the above-mentioned method bI of the present
invention, the alignment mark(s) is/are formed on the mold material
by dry-etching. Therefore, even when the mold material is made of
the hard material, cermet, silicon carbide (SiC) or amorphous
carbon, there are obtained alignment mark(s) maintaining a accuracy
higher than that accomplished by the grinding work or the
wet-etching. By using the alignment mark(s) as a reference, a
predetermined molding surface is formed on the mold material, i.e.,
the transfer molding surface constituted by a plurality of transfer
patterns is formed, making it easy to produce the mold having a
highly accurately formed transfer molding surface constituted by a
plurality of transfer patterns.
[0117] The mold produced by the method bI having the
above-mentioned advantages is used in combination with other
mold(s) produced by the method bI or in combination with mold(s)
produced according to a conventional method, so that there is
obtained a set of molds (including the one constituted by an upper
mold and a lower mold, the one constituted by an upper mold, a
lower mold and a sleeve mold, an the one in which a lower mold or
an upper mold is a flat plate) necessary for the press-molding.
[0118] Described below is the method bII of the present
invention.
[0119] The method bII of the present invention is for easily
producing a mold for press-molding, having a highly accurately
formed transfer molding surface constituted by a plurality of
transfer patterns like that of the method bI. According to this
method blI as described above, alignment mark(s) is/are formed by
dry-etching on the mold material, and the mold material is worked
with the alignment mark(s) as a reference, thereby to form a
transfer molding bare surface constituted by bare transfer patterns
that serve as bases for the transfer patterns. Then, the mold
release film is formed so as to cover at least the transfer molding
bare surface, thereby to obtain a mold in which the surface of the
mold release film serves as a transfer molding surface.
[0120] According to this method bII as described above, the
predetermined surface of the mold material after it is worked into
a desired shape is coated with the mold release film to obtain the
mold in which the surface of the mold release film serves as the
transfer molding surface. When the mold for press-molding a glass
molded article is to be obtained by the method bII, therefore, it
is desired that the mold is made of the hard material or cermet as
described concerning the mold A of the present invention. Even in
this case, it is allowed to use the mold material of silicon
carbide (SiC) or amorphous carbon.
[0121] The alignment mark(s) according to the method bII is/are
formed quite in the same manner as the formation of the alignment
mark(s) according to the above-mentioned method bI, and the
transfer molding bare surface according to the method bII is formed
quite in the same manner as the formation of the transfer molding
surface according to the above-mentioned method bI. Therefore,
their description is not repeated here.
[0122] The mold release film formed by the method bII is to prevent
the melt-adhesion between the mold and the shaping material during
the press-molding. Therefore, the material of the mold release film
is suitably selected depending upon the material of the mold that
is to be produced by the method bII and the material of the molded
article (shaping material that is to be molded) press-molded by
using the mold. For example, when the material such as the hard
material or cermet is used to obtain the mold for producing
press-molded glass articles, there is used, as the mold release
film, a film containing at least one component selected from the
group consisting of Pt, Au, Ir, Pd and Rh, or a film of
i-carbon.
[0123] The thickness of the mold release film can be suitably
selected depending upon the use of the mold that is produced, the
transfer patterns constituting the transfer molding bare surface
and the material of the mold release film, in order to prevent the
melt-adhesion between the mold and the shaping material, and so
that the bare transfer patterns constituting the transfer molding
bare surface will not be erased by the mold release film formed on
the transfer molding bare surface. The mold release film is formed
by, for example, sputtering method, ion-plating method, CVD method
or the like method by taking into consideration the material, use
of the mold that is obtained, productivity, etc.
[0124] In the above-mentioned method bII of the present invention,
too, alignment mark(s) is/are formed by dry-etching on the mold
material in the same manner as in the method bI of the present
invention. Therefore, even when the mold material is made of a
material such as hard material, cermet, silicon carbide (SiC) or
amorphous carbon, there is/are formed the alignment mark(s)
maintaining accuracy higher than that accomplished by the grinding
work or the wet-etching. Based upon the alignment mark(s), a
predetermined transfer molding bare surface is formed on the mold
material, i.e., a transfer molding bare surface constituted by a
plurality of bare transfer patterns is formed and, then, the mold
release film is formed so as to at least cover the transfer molding
bare surface, thereby to obtain a mold in which the surface of the
mold release film serves as the transfer molding surface. It is
thus made possible to easily produce the mold having a highly
accurately formed transfer molding surface constituted by a
plurality of transfer patterns.
[0125] The mold produced by the method bII having the
above-mentioned advantage is used in the same manner as the mold
produced by the above-mentioned method bI.
[0126] Next, described below is the mold CI of the present
invention.
[0127] As described earlier, the mold CI of the present invention
is for press-molding and has transfer pattern(s) of a predetermined
shape and of a high accuracy, exhibiting a long life. The mold CI
comprises a base member having a transfer molding bare surface of a
predetermined shape formed by dry-etching, and a mold release film
formed on the transfer molding bare surface so as to reflect the
shape of the transfer molding bare surface.
[0128] The base member is obtained by forming the transfer molding
bare surface on the mold material of a desired shape. As the
material of the base member, there can be used the hard material,
cermet, silicon carbide or amorphous carbon exemplified with
reference to the mold A of the present invention from the
standpoint of obtaining the mold that features the transfer
patterns of a long life. Among them, it is desired to use the hard
material or cermet.
[0129] The transfer molding bare surface formed on the base member
constitutes transfer pattern(s) together with the mold release film
that will be described later. Therefore, the shape of the transfer
molding bare surface is suitably selected depending upon the shape
of the article that is to be press-molded by using the mold CI.
When the article to be press-molded is a diffraction element, the
shape is suitably selected depending upon the shape of the surface
of the diffraction element, shape of the grooves in the diffraction
element, number or density of the grooves, area of the gradations,
and the like.
[0130] As described above, the transfer molding bare surface is
formed by dry-etching. Whether the transfer molding bare surface is
formed by dry-etching or grinding work, can be judged depending
upon whether there is a trace of grinding or polishing on the
transfer molding bare surface. Presence of the trace of grinding or
polishing indicates that it was formed by grinding work. Whether
the transfer molding bare surface is formed by dry-etching or
wet-etching can be determined depending upon the angle subtended by
the side surface at the base portion of the pattern formed by
etching and by the surface of the mold material (excluding the
surface of the pattern). When the angle is sharply rising at about
90.degree., then, it is formed by dry-etching.
[0131] Relying upon the dry-etching, it is allowed to highly
accurately form the transfer molding bare surface of a desired
shape regardless of whether the mold material is made of the hard
material, cermet, SiC or amorphous carbon.
[0132] In the mold CI, the mold release film is formed on the
transfer molding bare surface so as to reflect the shape of the
transfer molding bare surface, and the surface of the mold release
film serves as the transfer molding surface. That is, in the mold
CI, the transfer patterns are constituted by the transfer molding
bare surface formed on the base member and the mold release film
formed on the transfer molding bare surface.
[0133] The mold release film is to prevent the melt-adhesion
between the mold CI and the shaping material to be molded (shaping
preform) during the press-molding. The mold release film of various
compositions can be used depending upon the material of the base
member and the composition of the shaping material that is to be
molded. As the mold release film for preventing the melt-adhesion
between the mold CI and the glass shaping material, there can be
used a film containing at least one component selected from the
group consisting of Pt, Au, Ir, Pd and Rh, or a film of
i-carbon.
[0134] The thickness of the mold release film is suitably selected
depending upon the use of the mold that is obtained, shape of the
transfer molding bare surface, material of the mold release film
and shape of the desired transfer patterns, in order to prevent the
melt-adhesion between the mold and the shaping material that is to
be molded, and so that the shape of the transfer molding bare
surface is reflected on the mold release film. In practice,
however, it is desired that the thickness of the mold release film
is not less than roughly 0.03 .mu.m at the smallest.
[0135] The mold CI of the present invention equipped with the
above-mentioned base member and the mold release film, is combined
with predetermined mold(s) thereby to constitute a set of molds
(including the one constituted by an upper mold and a lower mold,
the one constituted by an upper mold, a lower mold and a sleeve
mold, and the one of which a lower mold or an upper mold is a flat
plate) which is necessary for obtaining a desired molded article by
press-molding.
[0136] In this case, the materials of the molds constituting the
set of molds may be the same or different. Or, the molds
constituting the set of molds may or may not have the mold release
film, except the mold CI. Moreover, the shapes of the molds
constituting the set of molds (shapes of transfer molding surfaces
of the molds) are suitably selected depending upon the shape of the
molded article that is to be obtained by press-molding. The
diffraction element may have a surface shape, e.g., a flat shape, a
concaved shape or a spherical shape depending upon its use.
Therefore, the shapes of the molds constituting the set of molds
(shapes of transfer molding surfaces of the molds) are suitably
selected so that the diffraction element having a desired surface
shape can be obtained.
[0137] In the mold CI of the present invention, the transfer
molding bare surface has been formed on the base member, and the
transfer patterns are constituted by the transfer molding bare
surface and the mold release film formed on the transfer molding
bare surface. Therefore, it is allowed to easily obtain a mold of
which the transfer patterns feature an extended life compared with
the conventional mold in which the transfer patterns are formed by
patterning the thin film formed on the base member into a
predetermined shape.
[0138] In the above-mentioned conventional mold, when a transfer
pattern (thin film after patterned) is peeled off, the mold cannot
be regenerated unless a predetermined thin film is formed after the
transfer pattern that has peeled off (thin film after patterned) is
removed, and the thin film is further patterned by the lithographic
method or the like method. In the mold CI of the present invention,
on the other hand, even when the mold release film constituting the
mold CI has peeled off, the mold CI can be regenerated if the mold
release film is simply formed after the mold release film that has
peeled off is removed. In this case, no patterning based on the
lithographic method is required and, hence, the mold is easily
regenerated.
[0139] In the mold CI of the present invention, furthermore, the
transfer molding bare surface is formed by dry-etching. This offers
an increased degree of freedom of the transfer molding bare surface
configuration for forming a mold and, hence, an increased degree of
freedom of the transfer patterns configuration, making it possible
to more easily form the transfer patterns maintaining high accuracy
compared with the case where the transfer molding bare surface is
formed by grinding the mold material.
[0140] The mold CI of the present invention having the
above-mentioned advantages can be produced by, for example, the
method cI of the present invention that will be described
later.
[0141] Next, described below is the mold CII of the present
invention.
[0142] Like the above-mentioned mold CI of the present invention,
the mold CII of the present invention is for press-molding and has
transfer patterns of a predetermined shape maintaining a high
accuracy, exhibiting a long life. The feature resides that the
transfer molding surface is formed on the mold material by
dry-etching.
[0143] Unlike the above-mentioned mold CI, however, the mold CII
has no mold release film. As the material of the mold CII,
therefore, it is desired to use the one which does not melt-adhere
to the shaping material (glass) during the press-molding and makes
it possible to obtain a mold of which the transfer patterns (shape
of the transfer molding surface) exhibit a long life. A concrete
example of the material for obtaining such a mold will be amorphous
carbon.
[0144] Since no mold release film is formed, the shape of the
transfer molding surface of the mold CII is different from the
shape of the transfer molding bare surface of the above-mentioned
mold CI. Except this point, however, the mold CII is substantially
the same as the mold CI produced by using a mold material
(amorphous carbon) that does not require mold release film.
Therefore, its description is not repeated here.
[0145] Like the above-mentioned mold CI, the mold CII of the
present invention is used in combination with predetermined mold(s)
to constitute a set of molds (including the one constituted by an
upper mold and a lower mold, the one constituted by an upper mold,
a lower mold and a sleeve mold, and the one of which a lower mold
or an upper mold is a flat plate) that is necessary for the
press-molding.
[0146] In the mold CII of the present invention, the transfer
molding surface has been formed on the mold material. Therefore, it
is allowed to easily obtain a mold of which the transfer patterns
exhibit a long life compared with the conventional molds in which
the thin film formed on the base member is patterned into a
predetermined shape to form transfer patterns.
[0147] According to the mold CII of the present invention in which
the transfer molding surface is formed by dry-etching, furthermore,
there is obtained an increased degree of freedom of the transfer
molding surface configuration for obtaining a mold and, hence, for
forming transfer patterns of a high accuracy more easily than when
the transfer molding surface is formed by grinding the mold
material.
[0148] The mold CII of the present invention having the
above-mentioned advantage can be produced by, for example, the
method cII of the present invention that will be described
later.
[0149] Next, described below is the method cI of the present
invention.
[0150] The above-mentioned method cI of the present invention
obtains a mold by obtaining a base member by forming, on the mold
material by dry-etching, the transfer molding bare surface that
serves as a base for the transfer molding surface, and by forming
the mold release film on the transfer molding bare surface so as to
reflect the shape of the transfer molding bare surface, the surface
of the mold release film serving as the transfer molding
surface.
[0151] This method cI is to obtain the above-mentioned mold CI. As
the mold material, therefore, it is desired to use the hard
material or cermet (described above with reference to the mold CI),
or SiC. It is allowable to use the amorphous carbon as a mold
material, as a matter of course.
[0152] The transfer molding bare surface is formed on the mold
material by dry-etching in the same manner as the formation of the
"shaping portion(s) for forming the alignment mark transfer
portion(s)" by the above-mentioned method aI or in the same manner
as the formation of the "alignment mark transfer portion(s)" by the
above-mentioned method aII. As described with reference to the mold
CI, the shape of the transfer molding bare surface is suitably
selected depending upon the shape of the molded article
press-molded by using the mold CI. In this case, it is desired that
the transfer molding bare surface is formed as accurately as
possible. For this purpose, the dry-etching conditions are suitably
selected depending upon the material of the mold.
[0153] As the mold release film formed on the transfer molding bare
surface formed by dry-etching so as to reflect the shape of the
transfer molding bare surface, there can be used those of a variety
of compositions depending upon the material of the base member and
the material of the mold. The thickness of the mold release film is
suitably selected depending upon the use of the mold that is
obtained, shape of the transfer molding bare surface, material of
the mold release film and shape of the desired transfer patterns,
so that there can be obtained desired transfer patterns reflecting
the shape of the transfer molding bare surface, as described with
reference to the mold CI. In practice, however, it is desired that
the thickness of the mold release film is not less than about 0.03
.mu.m at the smallest. The mold release film can be formed by, for
example, sputtering method, ion-plating method, CVD method or the
like method.
[0154] As described above, the mold release film is formed in order
to obtain a desired mold CI.
[0155] According to the above-mentioned method cI of the present
invention, the transfer molding bare surface is formed by
dry-etching. This offers an increased degree of freedom of the
transfer molding bare surface configuration and, hence, an
increased degree of freedom of the transfer patterns configuration,
making it possible to more easily form the transfer patterns
maintaining high accuracy compared with the case where the transfer
molding bare surface is formed by grinding the mold material.
[0156] Moreover, the base member is obtained by forming a transfer
molding bare surface on the mold material, and the transfer
patterns are constituted by the transfer molding bare surface and
the mold release film formed on the transfer molding bare surface.
Therefore, it is allowed to easily obtain a mold having transfer
patterns which feature a long life compared with the conventional
mold in which the transfer patterns are formed by patterning a thin
film formed on the base member into a predetermined shape.
[0157] Next, described below is the method cII of the present
invention.
[0158] The method cII of the present invention is to obtain the
mold by forming a transfer molding surface on the material of the
mold by dry-etching as described above.
[0159] This method cII is to obtain the mold (above-mentioned mold
CII of the present invention) by forming a transfer molding surface
(transfer patterns) on the mold material, and it is desired to use
the amorphous carbon as the mold material. It is allowable to use
the above-mentioned hard material, cermet or SiC as the mold
material as a matter of course.
[0160] The mold CII to be obtained by the method cII has no mold
release film and, hence, has the transfer molding surface of a
shape which is different from the shape of the transfer molding
bare surface in the mold CI. Except this point, however, the
transfer molding surface is formed by the method cII substantially
in the same manner as the formation of the transfer molding bare
surface at the time of producing the mold CI by the above-mentioned
method cI by using the mold material (amorphous carbon) that
requires no mold release film. Therefore, its description is not
repeated here.
[0161] According to the above-mentioned method cII of the present
invention, the transfer molding surface is formed by dry-etching.
This offers an increased degree of freedom of the transfer molding
surface configuration and, hence, an increased degree of freedom of
the transfer patterns configuration, making it possible to more
easily form the transfer patterns maintaining high accuracy
compared with the case where the transfer molding surface is formed
by grinding the mold material.
[0162] Moreover, the transfer molding surface (transfer patterns)
is formed on the mold material. Therefore, it is allowed to easily
obtain a mold having transfer patterns which feature a long life
compared with the conventional mold in which the transfer patterns
are formed by patterning a thin film formed on the base member into
a predetermined shape.
[0163] Next, described below is the method of producing a
diffraction element according to the present invention.
[0164] According to the method of the present invention as
described earlier, a glass diffraction element is produced relying
on the press-molding by using a set of molds including the mold CI
or the mold CII of the invention as an upper mold or a lower
mold.
[0165] Here, transfer patterns corresponding to rugged patterns
necessary for creating the function of the diffraction element are
formed in the mold CI or in the mold CII.
[0166] The set of molds (inclusive of the one constituted by an
upper mold and a lower mold, the one constituted by an upper mold,
a lower mold and a sleeve mold, and the one in which a lower mold
or an upper mold is a flat plate) used by this method includes an
upper mold or a lower mold which may be either the mold CI or the
mold CII of the present invention. The shape of the molds (shape of
the transfer molding surface in these molds) constituting the set
of molds is suitably selected depending upon the shape of the
diffraction element that is to be obtained. Moreover, the materials
of the molds constituting the set of molds may be the same or
different. Except the mold CI and the mold CII, furthermore, the
molds constituting the set of molds may or may not have the mold
release film.
[0167] The glass diffraction element can be produced in the same
manner as the conventional method in addition to using the
above-mentioned set of molds needed for the press-molding. That is,
a glass shaping material (preform) to be molded having a desired
composition is placed in a cavity formed by the set of molds, is
heated up to a temperature at which it can be deformed, is
compressed from a predetermined direction so that the surface
shapes of the molds (shapes of the transfer molding surfaces of the
molds) can be transferred onto the shaping material to be molded,
is cooled and, then, a molded article is taken out from the cavity
in the set of molds.
[0168] The method of producing the diffraction element of the
present invention uses the above-mentioned mold CI or the mold CII
of the present invention. These molds CI and CII have transfer
patterns that feature a longer life than that of the conventional
mold in which the transfer patterns are formed by patterning a thin
film formed on the base member into a predetermined shape.
Moreover, the molds CI and CII offer an increased degree of freedom
of the transfer molding bare surface configuration or the transfer
molding surface configuration, and make it possible to easily
obtain transfer patterns having high accuracy compared with the
conventional mold in which the transfer molding surface is formed
by grinding the mold material.
[0169] According to the method of producing the diffraction element
of the present invention, therefore, a glass diffraction element
having a desired shape can be produced at a low cost.
[0170] The present invention will now be described in further
detail by way of working examples to which only, however, the
invention is in no way limited.
EXAMPLE 1
[0171] (1) Preparation of a First Mold by the Method aI.
[0172] First, a hard material containing WC is used as a mold
material. The mold material has the shape of a flat plate measuring
20.0 mm long, 10.0 mm wide, 2.0 mm thick and having a maximum
surface roughness of 100 angstroms. Next, a positive-type
photo-resist (AZ1350 produced by Hoechst Co.) is applied by a
spin-coating method onto one surface of the mold material to form a
resist film 2 maintaining a thickness of 2.0 .mu.m on one surface
of the mold material 1 as shown in FIG. 1(a).
[0173] Next, a photomask of a predetermined shape is intimately
adhered onto the resist film 2. The photomask is made of an
ultraviolet ray-transmitting substrate of a rectangular shape
measuring 20.times.10 mm as viewed on a plane, having cross-shaped
light-shielding portions (10 .mu.m long, 10 .mu.m wide) of a Cr
film having a line width of 3.0 .mu.m at four corners of the
substrate. The photomask is adhered onto the resist film 2 so that
the light-shielding portions can be positioned on the side of the
resist film 2. Then, the resist film 2 is exposed to ultraviolet
ray (exposure of 25 mW/cm.sup.2) from the side of the photomask,
and is developed by being immersed in a predetermined developing
solution (AZ developer solution produced by Hoechst Co.) for 90
seconds.
[0174] Through the developing, the exposed portions of the resist
film 2 are dissolved and removed, and resist patterns 3 of a
crossed shape constituted by the portions that are not exposed to
light (portions that are not exposed to ultraviolet ray being
interrupted by the light-shielding portions formed on the
photomask) are formed at four corners on one surface of the mold
material 1 as shown in FIG. 1(b).
[0175] The resist patterns 3 have a crossed shape measuring 10
.mu.m long, 10 .mu.m wide, having a line width of 3.0 .mu.m as
viewed on a plane, and having a thickness of 2.0 .mu.m.
[0176] The resist patterns 3 are post-baked at 120.degree. C. for
60 minutes. Then, by using these resist patterns 3 as masks, one
surface of the mold material 1 is dry-etched for one minute. The
dry-etching is effected by using a reactive etching apparatus of
the type of Inductively Coupled Plasma, and a Cl.sub.2 gas is used
as an etching gas. The etching conditions consist of a coil bias of
600 W, a substrate bias of 300 W, an etching gas (Cl.sub.2 gas)
flow rate of 20.0 sccm, and a pressure of 5.0 mTorr.
[0177] Under the above-mentioned dry-etching conditions, the resist
patterns 3 are etched at a rate of 0.14 .mu.m/min, and the
thickness thereof decreases down to 1.86 .mu.m (hereinafter, the
resist patterns 3 after dry-etching are referred to as "resist
patterns 4", see FIG. 1(c)). Moreover, the surface of the mold
material 1 of the side on where the resist patterns 3 are formed is
etched at a rate of 0.03 .mu.m/min except the portions that are
protected by the resist patterns 3 (resist pattern 4). As a result
as shown in FIG. 1(c), there are formed protruded portions 6 of a
crossed shape which are 10 .mu.m long, 0.10 .mu.m wide, and 0.03
.mu.m high, having a line width of 3.0 .mu.m as viewed on a plane,
at four corners on one surface of the mold material 1 (hereinafter
referred to as "base member 5") after dry-etching. The protruded
portions 6 are utilized as shaping portions for forming alignment
mark transfer portions that will be described later and are
hereinafter referred to as "shaping portions 6 for forming the
alignment mark transfer portions".
[0178] Then, the resist patterns 4 are peeled off by using a
predetermined peeling solution to obtain a base member 5 for
forming a desired first mold. Referring to FIGS. 2(a) and 2(b), the
shaping portions 6 for forming the alignment mark transfer portions
are formed at four corners on one surface of the base member 5, and
the upper surfaces 6a of the shaping portions 6 (upper surfaces in
FIG. 2, the same holds in the following Examples 2 to 7) have a
maximum surface roughness of 100 angstroms. The surface 5a of the
base member 5 of the side where the shaping portions 6 are formed
(excluding the portions where the shaping portions 6 are formed) is
substantially flat and has a maximum surface roughness of 1000
angstroms.
[0179] Next, a mold release film comprising Au, Pt, Pd and Rh is
formed maintaining a thickness of 1500 angstroms (on the surface 5a
of the base member 5 and on the upper surfaces 6a of the shaping
portions 6) on the whole outer surface of the base member 5 of the
side where the shaping portions 6 are formed for forming the
alignment mark transfer portions by using an RF sputtering
apparatus. The sputtering is effected while adjusting the
atmosphere gas (Ar gas) flow rate to be 20.0 sccm, the atmosphere
pressure to be 1.0 Pa, and the RF bias to be 300 W.
[0180] Through the steps up to forming the mold release film, a
desired first mold is obtained. This mold is one of the molds A of
the present invention.
[0181] Referring to FIGS. 3(a) and 3(b), the first mold 10
comprises the base member 5, and the mold release film 7 formed on
the whole outer surface of the base member 5 on the side where the
shaping portions 6 are formed for forming the alignment mark
transfer portions. In the first mold 10, the surface of the mold
release film 7 is serving as a transfer molding surface 10a. On the
transfer molding surface 10a, there are formed four alignment mark
transfer portions 8 constituted by the shaping portions 6 for
forming the alignment mark transfer portions and the portions of
the mold release film covering the outer surfaces of the shaping
portions 6.
[0182] The upper surfaces 8a of the alignment mark transfer
portions (upper surfaces in FIG. 3(b), the same holds in the
following Examples 2 to 7) have a maximum surface roughness of 100
angstroms. On the transfer molding surface 10a, the portion
(peripheral portion) excluding the portions where the alignment
mark transfer portions 8 are formed, is substantially flat and has
a maximum surface roughness of 1000 angstroms.
[0183] (2) Preparation of a Second Mold.
[0184] A flat plate of a hard material containing WC and measuring
20 mm long, 10 mm wide, 2.0 mm thick and having a maximum surface
roughness of 100 angstroms, is used as a base member for a second
mold. Then, a mold release film comprising Au, Pt, Pd and Rh is
formed maintaining a thickness of 1500 angstroms by sputtering on
one surface of the base member under the conditions same as those
of when the above-mentioned first mold is obtained. Upon forming
the mold release film, a desired second mold is obtained.
[0185] In the above-mentioned second mold, the surface of the mold
release film formed on one surface of the base member serves as a
transfer molding surface.
[0186] Upon combining the above-mentioned first mold and the second
mold, there is obtained a set of molds of the side-free type
consisting of these two molds.
[0187] (3) Preparation of a Third Mold.
[0188] A base member is obtained by cutting and polishing a block
of a hard material containing WC into a cylinder of a predetermined
size, and a mold release film comprising Au, Pt, Pd and Rh is
formed maintaining a thickness of 1500 angstroms by sputtering on
the inner surface of the base member under the conditions same as
those of when the above-mentioned first mold is obtained, thereby
to obtain a desired third mold. The third mold has an inner size
which permits the above-mentioned first mold and the second mold to
be inserted therein maintaining a predetermined clearance. In this
mold, the surface of the mold release film formed on the inner
surface of the base member serves as a transfer molding
surface.
[0189] Upon combining the above-mentioned first mold, second mold
and third mold, there is obtained a set of molds constituted by
three molds, i.e., an upper mold (the first mold or the second
mold), a lower mold (the second mold or the first mold), and a
sleeve mold (the third mold).
[0190] (4) Press-Molding.
[0191] First, a set of molds is constituted by using the first mold
prepared in (1) above and the second mold prepared in (2) above,
and the first mold is secured to an upper holder of a press molding
machine in a manner that the transfer molding surface thereof
becomes the lower surface, and the second mold is secured to a
lower holder of the press molding machine in a manner that the
transfer molding surface thereof becomes the upper surface. A
preform of a soda lime glass measuring 20.0.times.10.0.times.2.0 mm
is placed on the lower mold (the second mold), and the
press-molding is effected in vacuum under the conditions of an
upper mold (the first mold) temperature of 660.degree. C., a lower
mold (the second mold) temperature of 630.degree. C., a pressing
force of 170 kg/cm.sup.2, and a pressing time of 120 seconds, in
order to obtain a rectangular plate-like optical element fixing
member measuring 20.5.times.10.3 mm as viewed on a plane.
[0192] Referring to FIG. 4, alignment marks 16 are formed in a
recessed manner having a crossed shape, as viewed on a plane, of 10
.mu.m long, 10 .mu.m wide and a depth of 0.03 .mu.m with a line
width of 3.0 .mu.m at four corners on one surface of the optical
element fixing member 15, the bottom surfaces 16a of the alignment
marks 16 having a maximum surface roughness of 80 angstroms. The
surface 15a of the optical element fixing member 15 of the side
where the alignment marks 16 are formed (excluding the alignment
marks 16) is substantially flat and has a maximum surface roughness
of 800 angstroms.
[0193] The alignment marks 16 can be easily identified by eyes
since the bottom surfaces 16a of the alignment marks 16 have the
maximum surface roughness different from the maximum surface
roughness on the periphery of the alignment marks 16.
[0194] The press-molding is effected in the same manner as
described above with the exception of constituting a set of molds
by using the first mold prepared in (1) above, second mold prepared
in (2) above, and third mold prepared in (3) above, fixing the
first mold onto the upper holder of the press molding machine in a
manner that the transfer molding surface thereof becomes the lower
surface, fixing the second mold onto the lower holder of the press
molding machine in a manner that the transfer molding surface
thereof becomes the upper surface, and using the third mold as a
sleeve mold. There is obtained a optical element fixing member same
as the optical element fixing member 15 shown in FIG. 4.
EXAMPLE 2
[0195] (1) Preparation of a First Mold by the Method aI.
[0196] First, a hard material containing WC is used as a mold
material. The mold material has the shape of a flat plate measuring
30.0 mm long, 20.0 mm wide, 1.0 mm thick and having a maximum
surface roughness of 100 angstroms. Next, resist patterns of a
crossed shape measuring 10 .mu.m long, 10 .mu.m wide, 2.0 .mu.thick
and having a line width of 3.0 .mu.m as viewed on a plane are
formed at four corners on one surface of the mold material quite in
the same manner as in Example 1(1).
[0197] The resist patterns are post-baked at 120.degree. C. for 60
minutes. Then, by using these resist patterns as masks, one surface
of the mold material is dry-etched for 10 minute. The dry-etching
is effected by using a reactive etching apparatus of the type of
Inductively Coupled Plasma, and an Ar gas and a CF, gas are used as
etching gases. The etching conditions consist of a coil bias of 600
W, a substrate bias of 600 W, an Ar gas flow rate of 20.0 sccm, a
CF.sub.4 gas flow rate of 10.0 sccm and a pressure of 5.0
mTorr.
[0198] Under the above-mentioned dry-etching conditions, the resist
patterns are etched at a rate of 0.08 .mu.m/min, and the thickness
of thereof decreases down to 1.2 .mu.m. Moreover, the surface of
the mold material of the side on where the resist patterns are
formed is etched at a rate of 0.03 .mu.m/min except the portions
that are protected by the resist patterns. As a result, there are
formed shaping portions for forming the alignment mark transfer
portions of the same shape as those formed in Example 1(1) at four
corners on one surface of the mold material (hereinafter referred
to as "base member") after dry-etching.
[0199] Then, the resist patterns are peeled off by using a
predetermined peeling solution to obtain a base member for forming
a first mold. The mold release film of the same composition and of
the same thickness as the one formed in Example 1(1) is formed on
the whole outer surface of the base member of the side where the
shaping portions are formed for forming the alignment mark transfer
portions according to the same method as that employed in Example
1(1).
[0200] Through the steps up to forming the mold release film, a
desired first mold is obtained. This mold is one of the molds A of
the present invention.
[0201] The first mold comprises the base member and the mold
release film, and in which the surface of the mold release film
serves as the transfer molding surface. On the transfer molding
surface are formed four alignment mark transfer portions
constituted by the shaping portions for forming the alignment mark
transfer portions and the portions of the mold release film
covering the outer surfaces of the shaping portions.
[0202] The upper surfaces of the alignment mark transfer portions
have a maximum surface roughness of 100 angstroms. On the transfer
molding surface, the portion (peripheral portion) excluding the
portions where the alignment mark transfer portions are formed, is
substantially flat and has a maximum surface roughness of 300
angstroms.
[0203] (2) Preparation of a Second Mold.
[0204] A second mold which, when combined with the above-mentioned
first mold, constitutes a set of molds of the side-free type, is
obtained quite in the same manner as in Example 1(2) but using a
base member of the shape of a flat plate of a hard material
containing WC measuring 30 mm long, 20 mm wide, 1.0 mm thick and
having a maximum surface roughness of 100 angstroms.
[0205] (3) Preparation of a Third Mold.
[0206] A third mold is obtained in the same manner as in Example
1(3) to constitute, when it is combined with the above-mentioned
first mold and the second mold, a set of molds comprising three
molds of an upper mold (the first mold or the second mold), a lower
mold (the second mold or the first mold) and a sleeve mold (the
third mold).
[0207] (4) Press-Molding.
[0208] The press-molding is effected in quite the same manner as in
Example 1(4) but using a set of molds constituted by using the
first mold and the second mold, and using, as a shaping material,
an alkali-free glass plate measuring 20.0.times.10.0.times.3.0 mm,
in order to obtain a optical element fixing member of a rectangular
shape measuring 20.0.times.10.0 mm as viewed on a plane.
[0209] At four corners on one surface of the optical element fixing
member, there are formed alignment marks in a recessed manner
having a crossed shape measuring 10 .mu.m long, 10 .mu.m wide, 0.3
.mu.m deep and having a line width of 3.0 .mu.m as viewed on a
plane. A maximum surface roughness is 80 angstroms on the bottom
surfaces of the alignment marks. The surface (excluding alignment
marks) of the optical element fixing member of the side where the
alignment marks are formed, is substantially flat and has a maximum
surface roughness of 800 angstroms.
[0210] The alignment marks can be easily identified by eyes since
the maximum surface roughness on the bottom surfaces of the
alignment marks is different from the maximum surface roughness on
the periphery of the alignment marks.
[0211] The press-molding is effected in the same manner as
described above with the exception of constituting a set of molds
by using the first mold, second mold and third mold, using the
first mold as the upper mold, the second mold as the lower mold and
the third mold as the sleeve mold, thereby to obtain a optical
element fixing member and having alignment marks similar to the one
described above.
EXAMPLE 3
[0212] (1) Preparation of a First Mold by the Method aII.
[0213] First, amorphous carbon is used as the mold material. The
mold material has the shape of a flat plate measuring 20.0 mm long,
10.0 mm wide, 3.0 mm thick and having a maximum surface roughness
of 200 angstroms. Next, a negative-type electron beam resist
(ZEP7000 produced by Nippon Zeon Co.) is applied by a spin-coating
method onto one surface of the mold material to form a resin layer
maintaining a thickness of 1.5 .mu.m on one surface of the mold
material.
[0214] Next, by using an electron beam (exposure of 55
.mu.C/cm.sup.2), equilateral triangles of a side of 50 .mu.m long
(each side having a line width of 5.0 .mu.m) are drawn at four
corners on the resin layer as viewed on a plane. The resin layer
after drawn with the electron beam is developed by being immersed
in a predetermined developing solution (ZEP500 produced by Nippon
Zeon Co.) for 90 seconds.
[0215] The portion of the resin layer that is not drawn with the
electron beam is dissolved and removed through the developing, and
resist patterns of portions drawn with the electron beam are formed
at four corners of the mold material. Each resist pattern has a
shape of equilateral triangle having a side of 50 .mu.m long and a
line width of 5.0 .mu.m as viewed on a plane, and having a
thickness of 1.5 .mu.m.
[0216] The resist patterns are post-baked at 200.degree. C. for 30
minutes. By using these resist patterns as masks, one surface of
the mold material is dry-etched for 10 minutes. The dry-etching is
conducted by using a reactive etching apparatus of the type of
Inductively Coupled Plasma, under the etching conditions same as
those of Example 1(1) but using an Ar gas as the etching gas.
[0217] Under the above-mentioned dry-etching conditions, the resist
patterns are etched at a rate of 0.11 .mu.m/min, and the thickness
thereof decreases down to 0.4 .mu.m. Moreover, the surface of the
mold material of the side on where the resist patterns are formed
is etched at a rate of 0.09 .mu.m/min, except the portions that are
protected by the resist patterns. As a result, there are formed
alignment mark transfer portions in a protruded manner of a height
of 0.9 .mu.m having an equilateral triangular frame shape of a side
of 50 .mu.m having a line width of 5.0 .mu.m as viewed on a plane
at four corners on one surface of the mold material after
dry-etching.
[0218] Thereafter, the resin layer is peeled off by using a
predetermined peeling solution to obtain a desired first mold. This
mold is one of the molds A of the present invention.
[0219] The first mold is made of amorphous carbon of the shape of a
rectangular flat plate measuring 20.0.times.10.0 mm as viewed on a
plane, and the whole outer surface of the side where the alignment
mark transfer portions are formed serves as a transfer molding
surface.
[0220] A maximum surface roughness is 200 angstroms on the upper
surfaces of the alignment mark transfer portions. On the transfer
molding surface, the portion (peripheral portion) excluding the
portions where the alignment mark transfer portions are formed is
substantially flat and has a maximum surface roughness of 500
angstroms.
[0221] (2) Preparation of a Second Mold.
[0222] A second mold which, when combined with the above-mentioned
first mold, constitutes a set of molds of the side-free type, is
obtained by cutting and polishing a block of amorphous carbon into
a flat plate measuring 20 mm long, 10 mm wide, 3.0 mm thick and
having a surface roughness of 200 angstroms. In this second mold,
one main surface serves as a transfer molding surface.
[0223] (3) Preparation of a Third Mold.
[0224] A block of amorphous carbon is cut and polished into a
cylinder of a predetermined size to obtain a third mold which, when
it is combined with the above-mentioned first mold and the second
mold, constitutes a set of molds comprising three molds of an upper
mold (the first mold or the second mold), a lower mold (the second
mold or the first mold) and a sleeve mold (the third mold).
[0225] (4) Press-Molding.
[0226] The press-molding is effected in quite the same manner as in
Example 1(4) but using a set of molds constituted by the first mold
and the second mold, and using, as a preform, a soda lime glass
measuring 15.0.times.10.0.times.3.0 mm, in order to obtain a
optical element fixing member of the shape of a rectangular plate
measuring 15.0.times.10.0 mm as viewed on a plane.
[0227] At four corners on one surface of the optical element fixing
member, there are formed alignment marks in a recessed manner 0.9
.mu.m deep in an equilateral triangular frame shape having a side
of 50 .mu.m and a line width of 5.0 .mu.m as viewed on a plane. A
maximum surface roughness is 180 angstroms on the bottom surfaces
of the alignment marks. The surface (excluding alignment marks) of
the optical element fixing member of the side where the alignment
marks are formed, is substantially flat and has a maximum surface
roughness of 450 angstroms.
[0228] The alignment marks can be easily identified by eyes since
the maximum surface roughness on the bottom surfaces of the
alignment marks is different from the maximum surface roughness on
the periphery of the alignment marks.
[0229] The press-molding is effected in the same manner as
described above with the exception of constituting a set of molds
by using the first mold, second mold and third mold, using the
first mold as the upper mold, the second mold as the lower mold and
the third mold as the sleeve mold, thereby to obtain a optical
element fixing member and having alignment marks similar to the one
described above.
EXAMPLE 4
[0230] (1) Preparation of a First Mold by the Method aI.
[0231] First, a hard material of the same composition as the hard
material used in Example 1 is used as the mold material. The mold
material has the shape of a flat plate measuring 20.0 mm long, 10.0
mm wide and 2.0 mm thick. One edge in the direction of length on
one surface of the mold material is cut and removed into a
predetermined width and a thickness to form a flat surface
(hereinafter, the flat surface that is polished as described later
is referred to as "flat surface for forming a first transfer
portion"). Furthermore, both edges (excluding the flat surface for
forming the first transfer portion) in the direction of width on
the surface of the mold material are cut and removed over a
predetermined width and thickness to form flat surfaces (a total of
two flat surfaces; hereinafter these flat surfaces after polished
are generally referred to as "flat surfaces for forming second
transfer portions"), and these flat surfaces are polished together
with the flat surface obtained above by grinding, so that a maximum
surface roughness becomes 100 angstroms. The flat surface for
forming the first transfer portion and the flat surfaces for
forming the second transfer portions, are located substantially on
a plane.
[0232] Next, the shaping portions for forming the alignment mark
transfer portions are formed on the mold material by dry-etching
the mold material (that has been subjected up to the step of
forming the flat surfaces for forming the two kinds of transfer
portions) quite in the same manner as in Example 1(1) with the
exception of setting the number of the shaping portions for forming
the alignment mark transfer portions to be two, and forming these
shaping portions near the two corners on the flat surface for
forming the first transfer portion (these corners are located at
the end on one side of the mold material in the direction of length
after it has been subjected up to the step of forming flat surfaces
for forming the two kinds of transfer portions).
[0233] Then, a portion of the mold material (hereinafter this
portion is referred to as "a region for forming protrusions for
V-grooves") surrounded by the flat surface for forming the first
transfer portion (the shaping portions have been formed thereon)
and by the flat surfaces for forming the second transfer portions,
is ground in order to form two protrusions in the region for
forming protrusions for V-grooves, the protrusions having an
isosceles triangular shape in vertical cross section in the
direction of width.
[0234] The protrusions are so formed as to maintain a predetermined
positional relationship relative to the shaping portions for
forming the alignment mark transfer portions and so that the ends
thereof on one side in the direction of length reaches the end of
the mold material on one side thereof in the direction of length.
These protrusions (hereinafter referred to as "protrusions for
V-grooves") are so designed that there are formed two V-grooves
(V-shaped grooves in vertical cross section in the direction of
width, the same holds hereinafter) of a depth of 120 .mu.m for
fixing optical fibers onto the optical element fixing member to be
obtained by using the desired first mold. The peripheries of the
two protrusions for V-grooves are flat, and these flat surfaces are
located substantially on a plane together with the flat surface for
forming the first transfer portion and the flat surfaces for
forming the second transfer portions.
[0235] The shaping portions for forming the alignment mark transfer
portions and the protrusions for V-grooves are formed on the mold
material thereby to obtain a base member for a desired first
mold.
[0236] Thereafter, the mold release film of the same composition
and the same thickness as the one formed in Example 1(1) is formed
on the whole outer surface of the base member on the side where the
shaping portions for forming the alignment mark transfer portions
and the protrusions for V-grooves are formed, according to the same
method as the one employed in Example 1(1) in order to obtain the
desired first mold. This first mold is one of the molds A of the
present invention.
[0237] The first mold comprises the base member and the mold
release film. In this first mold, the surface of the mold release
film serves as a transfer molding surface. In the transfer molding
surface, there are formed (1) two alignment mark transfer portions
constituted by the shaping portions for forming the alignment mark
transfer portions and portions of the mold release film covering
the outer surfaces of the shaping portions, and (2) two transfer
portions for V-grooves constituted by the protrusions for V-grooves
and portions of the mold release film covering the outer surface of
the protrusions for V-grooves.
[0238] The maximum surface roughness is 100 angstroms on the upper
surfaces of the alignment mark transfer portions. In the transfer
molding surface, furthermore, the portions excluding the alignment
mark transfer portions and the V-groove transfer portions, are
substantially flat, and the transfer molding surface in the
periphery of the alignment mark transfer portions has a maximum
surface roughness of 1000 angstroms.
[0239] (2) Preparation of a Second Mold.
[0240] A second mold that constitutes a set of molds of the
side-free type when it is combined with the above-mentioned first
mold, is obtained quite in the same manner as in Example 1(2).
[0241] (3) Preparation of a Third Mold.
[0242] A third mold is obtained in the same manner as in Example
1(3) to constitute, when it is combined with the above-mentioned
first mold and the second mold, a set of molds comprising three
molds of an upper mold (the first mold or the second mold), a lower
mold (the second mold or the first mold) and a sleeve mold (the
third mold).
[0243] (4) Press-Molding.
[0244] The optical element fixing member having a rectangular shape
as viewed on a plane is obtained by conducting the press-molding
quite in the same manner as in Example 1(4) with the exception of
constituting a set of molds using the first mold and the second
mold.
[0245] Referring to FIG. 5, in one surface of the optical element
fixing member 20, there are formed alignment marks 21a, 21b near
the two corners at an end on one side thereof in the direction of
length, the alignment marks 21, 21b being formed in a recessed
manner by the alignment mark transfer portions that are formed on
the first mold. In the surface of the optical element fixing member
20, furthermore, there are formed two V-grooves 22a, 22b by the
V-groove transfer portions that are formed on the first mold. The
V-grooves 22a and 22b are for fixing optical fibers onto the
optical element fixing member 20. The surface of the optical
element fixing member 20 of the side where alignment marks 21a, 21b
and V-grooves 22a, 22b are formed, is substantially flat except the
portions where the alignment marks 21a, 21b and the V-grooves 22a,
22b are formed.
[0246] The alignment mark 21a and the V-groove 22a are so formed
that a predetermined optical element 23 and an optical fiber are
optically connected together when the optical element 23
(photo-diode, laser diode, etc., see FIG. 5) having an alignment
mark 23a is fixed onto the optical element fixing member 20 by
utilizing the alignment mark 23a formed on the optical element 23
and alignment mark 21a formed on the optical element fixing member
20 and when the optical fiber (not shown) is fixed to the V-groove
22a.
[0247] The alignment mark 21b and the V-groove 22b are so formed
that a predetermined optical element 24 and an optical fiber are
optically connected together when the optical element 24
(photo-diode, laser diode, etc., see FIG. 5) having an alignment
mark 24a is fixed onto the optical element fixing member 20 by
utilizing the alignment mark 24a formed on the optical element 24
and the alignment mark 21b formed on the optical element fixing
member 20 and when the optical fiber (not shown) is secured to the
V-groove 22b.
[0248] The above-mentioned alignment marks 21a and 21b can be
easily identified by eyes since a maximum surface roughness is 80
angstroms on the bottom surfaces of the alignment marks 21a, 21b
and a maximum surface roughness is 800 angstroms on the periphery
of the alignment marks 21a, 21b.
[0249] A optical element fixing member having alignment marks
similar to the one mentioned above is obtained by conducting the
press-molding in the same manner as described above but by
constituting a set of molds using the first mold, second mold and
third mold, using the first mold as the upper mold, using the
second mold as the lower mold and using the third mold as the
sleeve mold.
EXAMPLE 5
[0250] (1) Preparation of a First Mold by the Method aI.
[0251] First, SiC is used as the mold material. The mold material
has the shape of a disk 50.0 mm in diameter and 3.0 mm thick. Then,
a region for forming protrusions for V-grooves is set onto a
predetermined portion on one surface of the mold material, a
portion other than the region for forming protrusions for V-grooves
is cut and removed by a predetermined thickness to form a flat
surface which is then polished so that a maximum surface roughness
is 100 angstroms (hereinafter, the surface after polished is
referred to as "flat surface for forming a transfer portion"). The
region for forming protrusions for V-grooves has a size same as the
size of the region for forming protrusions for V-grooves in Example
4(1).
[0252] Next, a negative-type electron beam resist (ZEP7000 produced
by Nippon Zeon Co.) is applied by a spin-coating method onto the
flat surface for forming a transfer portion in order to form a
resin layer maintaining a thickness of 1.5 .mu.m on one surface of
the mold material. By using an electron beam (exposure of 55
.mu.C/cm.sup.2), crosses of a predetermined size are drawn at
predetermined positions (a total of two places) on the resin layer.
The resin layer after drawn with the electron beam is developed by
being immersed in a predetermined developing solution (ZEP500
produced by Nippon Zeon Co.) for 90 seconds.
[0253] The portion of the resin layer that is not drawn with the
electron beam is dissolved and removed through the developing, and
resist patterns of portions drawn with the electron beam are formed
at predetermined two places. Each resist pattern has the shape of a
cross 10 .mu.m long and 10 .mu.m wide as viewed on a plane, and
having a line width of 3.0 .mu.m and a thickness of 1.5 .mu.m.
[0254] The resist patterns are post-baked at 200.degree. C. for 30
minutes. By using these resist patterns as masks, one surface of
the mold material is dry-etched for 10 minutes. The dry-etching is
conducted by using a reactive etching apparatus of the type of
Inductively Coupled Plasma. A CF.sub.4 gas is used as the etching
gas. The etching conditions consist of a coil bias of 300 W, a
substrate bias of 300 W, an etching gas (CF.sub.4 gas) flow rate of
30.0 sccm, and a pressure of 10.0 mTorr.
[0255] Under the above-mentioned dry-etching conditions, the resist
patterns are etched at a rate of 0.07 .mu.m/min. Moreover, the
surface of the mold material of the side on where the resist
patterns are formed is etched at a rate of 0.07 .mu.m/min except
the portions that are protected by the resist patterns. As a
result, there are formed the shaping portions for forming the
alignment mark transfer portions in a protruded manner of a height
of 0.7 .mu.m having a crossed shape 10 .mu.m long, 10 .mu.m wide
and having a line width of 3.0 .mu.m as viewed on a plane at
predetermined portions (a total of two places) on one surface of
the mold material after dry-etching.
[0256] Thereafter, the region for forming protrusions for V-grooves
is ground in the same manner as in Example 4(1) to form two
protrusions for V-grooves to obtain a base member for a desired
first mold. A mold release film having the same composition and the
thickness as the one formed in Example 1(1) is formed on one
surface of the base member (on the surface of the side where there
are formed the shaping portions for forming the alignment mark
transfer portions and the protrusions for V-grooves) by the method
same as the one employed in Example 1(1) to obtain the desired
first mold. This first mold is one of the molds A of the present
invention.
[0257] The first mold comprises the base member and the mold
release film like the first mold obtained in Example 4(1). In the
first mold, the surface of the mold release film serves as a
transfer molding surface. On the transfer molding surface are
formed two alignment mark transfer portions and two V-groove
transfer portions like that of the first mold produced in Example
4(1).
[0258] The alignment mark transfer portions and the V-groove
transfer portions are formed maintaining quite the same positional
relationship as that of the first mold obtained in Example 4(1),
and a maximum surface roughness is 100 angstroms on the upper
surfaces of the alignment mark transfer portions. On the transfer
molding surface, the portion excluding the portions where the
alignment mark transfer portions and the V-groove transfer portions
are formed, is substantially flat and has a maximum surface
roughness of 1000 angstroms.
[0259] (2) Preparation of a Second Mold.
[0260] A second mold which, when combined with the above-mentioned
first mold, constitutes a set of molds of the side-free type, is
obtained in quite the same manner as in Example 4(2) with the
exception of using, as a base member, a disk made of SiC having a
diameter of 50.0 mm, a thickness of 3.0 mm and a maximum surface
roughness of 100 angstroms.
[0261] (3) Preparation of a Third Mold.
[0262] A third mold is obtained in the same manner as in Example
1(3) but using a block of SiC to constitute, when it is combined
with the above-mentioned first mold and the second mold, a set of
molds comprising three molds of an upper mold (the first mold or
the second mold), a lower mold (the second mold or the first mold)
and a sleeve mold (the third mold).
[0263] (4) Press-Molding.
[0264] A optical element fixing member having the same shape and
the size as the optical element fixing member obtained in Example
4(4), is obtained by conducting the press-molding in quite the same
manner as in Example 4(4) with the exception of constituting a set
of molds using the first mold and the second mold. In conducting
the press-forming, the preform is so disposed that there is
obtained the optical element fixing member having a desired
shape.
[0265] In the thus obtained optical element fixing member, the
alignment marks are easily identified by eyes since a maximum
surface roughness is 80 angstroms on the bottom surfaces of the
alignment marks and a maximum surface roughness is 800 angstroms on
the periphery of the alignment marks.
[0266] A optical element fixing member having alignment marks
similar to the one mentioned above is obtained by conducting the
press-molding in the same manner as described above but by
constituting a set of molds using the first mold, second mold and
third mold, using the first mold as the upper mold, using the
second mold as the lower mold and using the third mold as the
sleeve mold.
EXAMPLE 6
[0267] (1) Preparation of a First Mold by the Method aI.
[0268] A mold is obtained in quite the same manner as in Example
2(1) but changing the shape and the positions of the alignment mark
transfer portions as viewed on a plane. This mold has a total of
eight alignment mark transfer portions of an L-shape 10 .mu.m long,
10 .mu.m wide and having a line width of 3.0 .mu.m as viewed on a
plane. Among the eight alignment mark transfer portions, four are
so formed as will be overlapped on any of the four corners of a
first rectangle having a predetermined size thereby to constitute a
first group of alignment mark transfer portions. The remaining four
alignment mark transfer portions are so formed as will be
overlapped on any of the four corners of a second rectangle having
the same size as the first rectangle and are arranged in the
direction of width of the first mold maintaining a predetermined
distance from the first rectangle. The remaining four alignment
mark transfer portions form a second group of alignment mark
transfer portions.
[0269] A maximum surface roughness is 100 angstroms on the upper
surfaces of the alignment mark transfer portions that constitute
the first group of alignment mark transfer portions and the second
group of alignment mark transfer portions. On the transfer molding
surface of the mold, the portion (peripheral portion) excluding the
portions where the alignment mark transfer portions are formed, is
substantially flat and has a maximum surface roughness of 1000
angstroms. This mold forms a first mold being combined with a mold
that will be described next, and is hereinafter referred to as
"mold 1a".
[0270] Separately from the above-mentioned mold 1a, a mold 1b is
prepared in a manner as described below.
[0271] As a mold material, first, there is used a flat plate of a
rectangular shape as viewed on a plane of a hard material having
the same composition as that of the above-mentioned mentioned mold
1a. Edges on both sides on one surface of the mold material in the
direction of width are cut and removed over a predetermined width
and a thickness to form flat surfaces (a total of two surfaces).
These flat surfaces are polished such that their maximum surface
roughness is 100 angstroms (hereinafter, these surfaces are
referred to as "flat surfaces for forming transfer portions").
[0272] Then, the shaping portions for forming the alignment mark
transfer portions are formed on the mold material by dry-etching
the mold material (on which have been formed flat surfaces for
forming the transfer portions) in quite the same manner as in
Example 1(1) with the exception of setting the number of the
shaping portions for forming the alignment mark transfer portions
to be two and forming the shaping portions at predetermined
portions on the flat surfaces for forming the transfer
portions.
[0273] Next, a portion of the mold material sandwiched by the two
flat surfaces for forming the transfer portions as viewed on a
plane, is ground in the same manner as in Example 4(1) to form two
protrusions for V-grooves, thereby to obtain a base member for a
desired mold (mold 1b). The protrusions for V-grooves are so formed
as to maintain a predetermined positional relationship relative to
the shaping portions for forming the alignment mark transfer
portions on the base member, and as to reach the end of the other
side of the base member from the end of the one side thereof in the
direction of length. Moreover, the protrusions for V-grooves are so
designed as to form two V-grooves of a depth of 120 .mu.m for
fixing optical fibers onto the optical element fixing member when
the optical element fixing member is obtained by utilizing the
first mold that is finally obtained.
[0274] Next, a mold release film comprising Au, Pt, Pd and Rh
maintaining a thickness of 1500 angstroms is formed on the whole
outer surface of the base member on the side where there are formed
the shaping portions for forming the alignment mark transfer
portions and the protrusions for V-grooves in quite the same manner
as in Example 1(1) in order to obtain a desired mold 1b.
[0275] In the transfer molding surface of the mold 1b are formed
the alignment mark transfer portions and the V-groove transfer
portions, and a maximum surface roughness is 100 angstroms on the
upper surfaces of the alignment mark transfer portions. On the
transfer molding surface of the mold 1b, furthermore, the portion
excluding the portions where the alignment mark transfer portions
and the V-groove transfer portions are formed, is substantially
flat and has a maximum surface roughness of 1000 angstroms.
[0276] Thereafter, the above-mentioned mold 1a and the mold 1b are
combined together using a fixing frame so that the transfer molding
surfaces formed in these molds face the same direction, thereby to
obtain a desired first mold.
[0277] In the thus obtained first mold, the transfer molding
surface (excluding the alignment mark transfer portions) of the
mold 1a is more protruded than the transfer molding surface
(excluding the alignment mark transfer portions and the V-groove
transfer portions) of the mold 1b, and the alignment mark transfer
portions formed on the mold 1b are located on the side of one end
of the first mold in the direction of length. The first mold has a
rectangular shape as viewed on a plane.
[0278] (2) Preparation of a Second Mold.
[0279] A second mold which, when combined with the above-mentioned
first mold, constitutes a set of molds of the side-free type, is
obtained in quite the same manner as in Example 1(2).
[0280] (3) Preparation of a Third Mold.
[0281] A third mold is obtained in the same manner as in Example
1(3) to constitute, when it is combined with the above-mentioned
first mold and the second mold, a set of molds comprising three
molds of an upper mold (the first mold or the second mold), a lower
mold (the second mold or the first mold) and a sleeve mold (the
third mold).
[0282] (4) Press-Molding.
[0283] A optical element fixing member having a rectangular shape
on a plane is obtained by conducting the press-molding in quite the
same manner as in Example 1(4) with the exception of constituting a
set of molds using the first mold and the second mold, and using,
as a preform, an alkali-free glass plate of a rectangular shape
having a predetermined size as viewed on a plane.
[0284] As shown in FIG. 6, the optical element fixing member 30
have a pedestal 31 formed by the mold 1a and an optical
fiber-engaging portion 32 formed by the mold 1b. The pedestal 31 is
lower by a step than the optical fiber-engaging portion. At nearly
the center in the upper surface of the pedestal 31 as viewed on a
plane, there are formed, in a recessed manner, four alignment marks
33a, 33b, 33c and 33d relying upon the first group of alignment
mark transfer portions formed on the mold 1a, and four alignment
marks 34a, 34b, 34c and 34d relying upon the second group of
alignment mark transfer portions formed on the mold 1a. The
peripheries of these alignment marks are substantially flat.
[0285] In the optical fiber-engaging portion 32, on the other hand,
there are formed two V-grooves 32a, 32b relying upon the V-groove
transfer portions formed on the mold 1b, and two alignment marks
35a, 35b in a recessed manner relying upon the alignment mark
transfer portions formed on the mold 1b. The V-grooves 32a and 32b
are to fix the optical fibers, and has a depth of 120 .mu.m. The
alignment marks 35a and 35b are formed at the end on one side of
the optical element fixing member 30 in the direction of length.
The surface of the optical fiber-engaging portion 32 on which the
V-grooves 32a, 32b and alignment marks 35a, 35b are formed, is
substantially flat but excluding the V-grooves 32a, 32b and the
alignment marks 35a, 35b.
[0286] The alignment marks 33a, 33b, 33c, 33d (hereinafter often
referred to as "a first group of alignment marks") and the V-groove
32a are so formed that an optical element 36 (photodiode or laser
diode, see FIG. 6) and an optical fiber are optically connected
together when the optical element 36 of a rectangular shape having
a predetermined size as viewed on a plane is positioned by
utilizing the first group of alignment marks and is fixed to the
optical element fixing member 30 and when the optical fiber is
fixed to the V-groove 32a.
[0287] Furthermore, the alignment marks 34a, 34b, 34c, 34d
(hereinafter often referred to as "a second group of alignment
marks") and the V-groove 32b are so formed that an optical element
37 (photodiode or laser diode, see FIG. 6) and an optical fiber are
optically connected together when the optical element 37 of a
rectangular shape having a predetermined size as viewed on a plane
is positioned by utilizing the second group of alignment marks and
is fixed to the optical element fixing member 30 and when the
optical fiber is fixed to the V-groove 32b.
[0288] The alignment marks 33a, 33b, 33c, 33d, 34a, 34b, 34c and
34d are easily identified by eyes since a maximum surface roughness
is 80 angstroms on the bottom surfaces of the alignment marks 33a,
33b, 33c and 33d that constitute the first group of alignment
marks, a maximum surface roughness is 80 angstroms on the bottom
surfaces of the alignment marks 34a, 34b, 34c and 34d that
constitute the second group of alignment marks, and a maximum
surface roughness is 800 angstroms on the periphery of the
alignment marks (on the surface of the pedestal 31). Similarly, the
alignment marks 35a and 35b are easily identified by eyes since a
maximum surface roughness is 80 angstroms on the bottom surfaces of
the alignment marks 35a and 35b and a maximum surface roughness is
800 angstroms on the periphery of the alignment marks (on the
surface of the optical fiber-engaging portion 32).
[0289] A optical element fixing member and having alignment marks
similar to the one mentioned above is obtained by conducting the
press-molding in the same manner as described above but by
constituting a set of molds using the first mold, second mold and
third mold, using the first mold as the upper mold, using the
second mold as the lower mold and using the third mold as the
sleeve mold.
EXAMPLE 7
[0290] (1) Preparation of a First Mold by the Method aII.
[0291] First, a flat plate of amorphous carbon measuring 20.0 mm
long, 10.0 mm wide, 3.0 mm thick and having a maximum surface
roughness of 200 angstroms is used as a mold material, and a flat
surface for forming a first transfer portion and a flat surface for
forming a second transfer portion are formed on one surface of the
mold material in quite the same manner as in Example 4(1).
[0292] Next, alignment mark transfer portions are formed on the
mold material by dry-etching the mold material (on which has been
formed the two kinds of flat surfaces for forming the transfer
portions) in quite the same manner as in Example 3(1) with the
exception of setting the number of the alignment mark transfer
portions to be two, forming the alignment mark transfer portions in
a crossed shape as viewed on a plane, and forming the alignment
mark transfer portions at positions near the two corners on the
flat surface for forming the first transfer portion (the corners
are located at an end on one side in the lengthwise direction of
the mold material on which have been formed two kinds of flat
surfaces for forming transfer shaping portions).
[0293] The flat surface for forming the second transfer portions is
ground in the same manner as in Example 4(1) to form two V-groove
transfer portions comprising protrusions of an isosceles triangular
shape in vertical cross section in the direction of width.
[0294] Upon forming the alignment mark transfer portions and the
V-groove transfer portions, there is obtained a desired first mold.
This first mold is one of the molds A of the present invention.
[0295] The above-mentioned first mold comprises amorphous carbon of
the shape of a rectangular flat plate measuring 20.0.times.10.0 mm
as viewed on a plane, and the whole outer surface of the side where
the alignment mark transfer portions and the V-groove transfer
portions are formed, serves as the transfer molding surface. The
V-groove transfer portions are so formed as to maintain a
predetermined positional relationship relative to the alignment
mark transfer portions, and the end on one side thereof in the
lengthwise direction reaches the end on one side in the lengthwise
direction of the first mold. The V-groove transfer portions are so
designed as to form two V-grooves of a depth of 120 .mu.m for
fixing the optical fibers to the optical element fixing member when
the optical element fixing member is obtained by using the
mold.
[0296] A maximum surface roughness is 100 angstroms on the upper
surfaces of the alignment mark transfer portions. On the transfer
molding surface, the portions excluding the portions where the
alignment mark transfer portions and the V-groove transfer portions
are formed, are substantially flat. The transfer molding surface in
the periphery of the alignment mark transfer portions has a maximum
surface roughness of 1000 angstroms.
[0297] (2) Preparation of a Second Mold.
[0298] A second mold which, when combined with the above-mentioned
first mold, constitutes a set of molds of the side-free type, is
obtained in quite the same manner as in Example 3(2).
[0299] (3) Preparation of a Third Mold.
[0300] A third mold is obtained in the same manner as in Example
3(3) to constitute, when it is combined with the above-mentioned
first mold and the second mold, a set of molds comprising three
molds of an upper mold (the first mold or the second mold), a lower
mold (the second mold or the first mold) and a sleeve mold (the
third mold)
[0301] (4) Press-Molding.
[0302] A optical element fixing member having nearly the same shape
as that of the optical element fixing member obtained in Example
4(4), is obtained by conducting the press-molding in the same
manner as in Example 3(4) with the exception of constituting a set
of molds using the first mold and the second mold.
[0303] In the thus obtained optical element fixing member, the
alignment marks are easily identified by eyes since a maximum
surface roughness is 80 angstroms on the bottom surfaces of the
alignment marks and a maximum surface roughness is 800 angstroms on
the periphery of the alignment marks.
[0304] A optical element fixing member having alignment marks
similar to the one mentioned above is obtained by conducting the
press-molding in the same manner as described above but by
constituting a set of molds using the first mold, second mold and
third mold, using the first mold as the upper mold, using the
second mold as the lower mold and using the third mold as the
sleeve mold.
EXAMPLE 8
Preparation of a Mold by the Method bI
[0305] Use is made of a mold material having the same composition,
shape and surface roughness as those of the mold material used in
Example 1(1), a resist film having a thickness of 2.0 .mu.m is
formed on one surface of the mold material in the same manner as in
Example 1(1), and the resist film is exposed and is developed in
the same manners as in Example 1(1) to form resist patterns of a
crossed shape at four corners on one surface of the mold material.
The resist patterns have a crossed shape 10 .mu.m long and 10 .mu.m
wide as viewed on a plane, and has a thickness of 2.0 .mu.m.
[0306] The resist patterns are post-baked at 120.degree. C. for 60
minutes. Then, by using these resist patterns as masks, one surface
of the mold material is dry-etched for 10 minutes. The dry-etching
is effected by using a reactive etching apparatus of the type of
Inductively Coupled Plasma, and an Ar gas and a CF, gas are used as
etching gases. The etching conditions are the same as the
dry-etching conditions in Example 2(2).
[0307] Under the above-mentioned dry-etching conditions, the resist
patterns are etched at a rate of 0.08 .mu.m/min, and the thickness
of thereof decreases down to 1.2 .mu.m. Moreover, the surface of
the mold material of the side on where the resist patterns are
formed is etched at a rate of 0.03 .mu.m/min except the portions
that are protected by the resist patterns. As a result, there are
formed protruded alignment marks of a crossed shape which are 10
.mu.m long, 10 .mu.m wide, and 0.3 .mu.m high, having a line width
of 3.0 .mu.m as viewed on a plane, at four corners on one surface
of the mold material after drying-etching.
[0308] The resist patterns are peeled off by using a predetermined
peeling solution. Then, by using one of the alignment marks as
references, a first groove and a second groove having a V-shape in
vertical cross section in the direction of width are formed by
using a grinding machine.
[0309] Referring to FIGS. 7(a) and 7(b), the first groove 41a and
the second groove 41b are so formed as to maintain a predetermined
distance between the center axes thereof in the lengthwise
direction and the center of the alignment mark 42a as viewed on a
plane, and so that they are located on the center side of the mold
material inside of the alignment mark 42a when viewed in the
lengthwise direction. The first groove 41a and the second groove
41b are so formed that when a molded article is press-molded by
using a desired mold, the optical fiber can be engaged and
positioned between the protrusion press-molded by the first groove
41a and the protrusion press-molded by the second groove 41b.
[0310] Furthermore, a third groove and a fourth groove having a
V-shape in vertical cross section in the direction of width are
formed by using the grinding machine with the alignment mark 42b
(see FIG. 7) as a reference.
[0311] Referring to FIGS. 7(a) and 7(b), the third groove 43a and
the fourth groove 43b are so formed as to maintain a predetermined
distance between the center axes thereof in the lengthwise
direction and the center of the alignment mark 42b as viewed on a
plane, and so that they are located on the center side of the mold
material inside of the alignment mark 42b when viewed in the
lengthwise direction. The third groove 43a and the fourth groove
43b are so formed that when a molded article is press-molded by
using a desired mold, the optical fiber can be engaged and
positioned between the protrusion press-molded by the third groove
43a and the protrusion press-molded by the fourth groove 43b.
[0312] Upon forming the above-mentioned first groove 41a, second
groove 41b, third groove 43a and fourth groove 43b, there is formed
a transfer molding surface 44 constituted by a transfer pattern of
the flat surface, a transfer pattern of the first groove 41a, a
transfer pattern of the second groove 41b, a transfer pattern of
the third groove 43a, a transfer pattern of the fourth groove 43b,
and transfer patterns of alignment marks 42a, 42b, 42c and 42d,
and, at the same time, there is obtained a desired mold 45 (see
FIGS. 7(a) and 7(b)).
[0313] The mold 45 has a rectangular shape measuring
20.0.times.10.0 mm as viewed on a plane, and has the transfer
molding surface 44 formed on one main surface thereof. A maximum
surface roughness is 100 angstroms on the upper surfaces of the
alignment marks 42a, 42b, 42c and 42d (on the upper surface in FIG.
7(b), the same holds in the following Examples 9 to 11), and a
maximum surface roughness is 1000 angstroms on the periphery of the
alignment marks 42a, 42b, 42c and 42d.
[0314] A glass molded article (optical element fixing member) is
press-molded by using the above-mentioned mold 45, optical fibers
are engaged between the protrusion formed on the molded article by
the first groove 41a and the protrusion formed on the molded
article by the second groove 41b, and between the protrusion formed
on the molded article by the third groove 43a and the protrusion
formed on the molded article by the fourth groove 43b, and these
optical fibers are secured by using a holding member. By using the
above-mentioned mold 45, another glass molded article (optical
element fixing member) is prepared, and optical fibers (a total of
two optical fibers) are engaged and secured onto the molded article
in the same manner as described above. The optical fibers engaged
and secured onto the one molded article and the optical fibers
engaged and secured onto the other molded article, are optically
connected together relying only upon the mechanical positioning
between these molded articles (optical element fixing members). The
optical fibers can be connected together with low loss.
EXAMPLE 9
Preparation of the Mold by the Method bI
[0315] First, amorphous carbon is used as the mold material. The
mold material has the shape of a flat plate measuring 50.0 mm long,
50.0 mm wide, 3.0 mm thick and having a maximum surface roughness
of 120 angstroms.
[0316] Next, a resin layer is formed on one surface of the mold
material by applying a negative-type electron beam resist in the
same manner as in Example 3(1). Then, in the same manner as in
Example 3(1), the electron beam drawing is effected, the resin
layer is developed, the resist pattern is formed, the resist
pattern is post-baked, dry-etching is effected, and the resist
pattern is peeled off, in order to form alignment marks in a
protruded manner having the shape of an equilateral triangle frame
of a side of 50 .mu.m with a line width of 5.0 .mu.m as viewed on a
plane, and having a height of 0.9 .mu.m, at four corners on one
surface of the mold material.
[0317] Then, by using a grinder, a total of 16 grooves are formed
having a V-shape in vertical cross section in the direction of
width maintaining a pitch of 125 .mu.m with the alignment marks as
references. These grooves are so formed that, when an molded
article is press-molded by using a desired mold, the optical fibers
can be engaged and positioned among the protrusions (among the
neighboring protrusions) formed on the molded article by the
grooves.
[0318] Upon forming the above-mentioned grooves, there is formed a
transfer molding surface constituted by a transfer pattern of the
flat surface, transfer patterns of the total of 16 grooves and
transfer patterns of the alignment marks, and, at the same time,
there is obtained a desired mold.
[0319] The mold has a rectangular shape measuring 50.0.times.50.0
mm as viewed on a plane, and has the transfer molding surface
formed on one main surface thereof. A maximum surface roughness is
120 angstroms on the upper surfaces of the alignment marks, and a
maximum surface roughness is 1100 angstroms on the periphery of the
alignment marks.
[0320] Two glass molded articles (optical element fixing member)
are prepared by using the above-mentioned mold, and the optical
fibers are optically connected together by using these optical
element fixing member in the same manner as in Example 8. The same
results as those of Example 8 are obtained.
EXAMPLE 10
Preparation of the Mold by the Method bI
[0321] First, a cermet comprising chiefly Al.sub.2O.sub.3 is used
as the mold material. The mold material has the shape of a flat
plate measuring 40.0 mm long, 40.0 mm wide, 2.0 mm thick and having
a maximum surface roughness of 110 angstroms. Next, resist patterns
of a crossed shape 10 .mu.m long, 10 .mu.m wide and having a line
width of 5.0 .mu.m as viewed on a plane and a thickness of 2.0
.mu.m are formed at four corners on one surface of the mold
material in the same manner as in Example 9.
[0322] The resist patterns are post-baked at 200.degree. C. for 30
minutes. By using the resist patterns as masks, one surface of the
mold material is dry-etched for 5 minutes. The dry-etching is
effected by using a reactive etching apparatus of the type of
Inductively Coupled Plasma, and an Ar gas is used as the etching
gas. The etching conditions consist of a coil bias of 600 W, a
substrate bias of 600 W, an etching gas (Ar gas) flow rate of 30.0
sccm, and a pressure of 5.0 mTorr.
[0323] Through the dry-etching under the above-mentioned
conditions, the resist patterns are etched at a rate of 0.13
.mu.m/min. The surface of the mold material of the side where the
resist patterns are provided is etched at a rate of 0.11 .mu./min
except the portions protected by the resist patterns. As a result,
alignment marks are formed in a protruded manner having a crossed
shape as viewed on a plane and having a height of 0.5 .mu.m at four
corners on one surface of the mold material after dry-etching, and
a flat surface is formed in the periphery thereof.
[0324] The resist patterns are peeled off by using a predetermined
peeling solution, and a total of four grooves having a V-shape in
vertical cross section in the direction of width are formed by
using a grinder in quite the same manner as in Example 8. Upon
forming these grooves, there is formed a transfer molding surface
constituted by a transfer pattern of the flat surface, transfer
patterns of the total of four grooves and transfer patterns of the
alignment marks, and, at the same time, there is obtained a desired
mold.
[0325] The mold has a rectangular shape measuring 40.0.times.40.0
mm as viewed on a plane, and has the transfer molding surface
formed on one main surface thereof. A maximum surface roughness is
110 angstroms on the upper surfaces of the alignment marks, and a
maximum surface roughness is 1100 angstroms on the periphery of the
alignment marks.
[0326] Two glass molded articles (optical element fixing member)
are press-molded by using the above-mentioned mold, and the optical
fibers are optically connected together by using these optical
element fixing members in the same manner as in Example 8. There
are obtained the same results as those of Example 8.
EXAMPLE 11
Preparation of a Mold by the Method bII
[0327] Use is made of a mold material having the same composition,
shape and maximum surface roughness as those of the mold material
used in Example 8, and resist patterns having a crossed shape as
viewed on a plane and having a line width of 10.0 .mu.m and a
thickness of 4.0 .mu.m are formed at four corners on one surface of
the mold material in the same manner as in Example 8.
[0328] The resist patterns are post-baked at 120.degree. C. for 60
minutes. By using these resist patterns as masks, one surface of
the mold material is dry-etched for one minute. The dry etching is
effected by using a reactive etching apparatus of the type of
Inductively Coupled Plasma, and a Cl.sub.2 gas is used as the
etching gas. The etching conditions consist of a coil bias of 600
W, a substrate bias of 600 W, an etching gas (Cl.sub.2 gas) flow
rate of 20.0 sccm, and a pressure of 5.0 mTorr.
[0329] Through the dry-etching under the above-mentioned
conditions, the resist patterns are etched at a rate of 0.28
.mu.m/min and the thickness decreases down to 3.72 .mu.m. The
surface of the mold material of the side where the resist patterns
are provided is etched at a rate of 0.05.mu./min except the
portions protected by the resist patterns. As a result, alignment
marks are formed in a protruded manner having a crossed shape as
viewed on a plane and having a height of 0.05 .mu.m at four corners
on one surface of the mold material after dry-etching, and a flat
surface is formed in the periphery thereof.
[0330] The resist patterns are peeled off by using a predetermined
peeling solution, and a total of 16 grooves having a U-shape in
vertical cross section in the direction of width are formed by
using a grinder using one of the alignment mark as references. The
grooves are so formed that the optical fibers can be engaged and
positioned among the protrusions (among the neighboring
protrusions) formed on the molded article by the grooves when the
article is press-molded by using a desired mold.
[0331] Upon forming these grooves, there is formed a transfer
molding bare surface constituted by a bare transfer pattern of the
flat surface, bare transfer patterns of the total of 16 grooves and
bare transfer patterns of the alignment marks.
[0332] Next, by using an RF magnetron sputtering apparatus, a mold
release film comprising Au, Pt, Pd and Rh and having a thickness of
1500 angstroms is formed so as to cover the transfer molding bare
surface. The sputtering is effected while setting the atmosphere
gas (Ar gas) flow rate to be 20.0 sccm, setting the pressure of
atmosphere to be 1.0 Pa, and the RF bias to be 300 W.
[0333] Upon forming the mold release film, there is obtained a
desired mold. In this mold, the surface of the mold release film
serves as the transfer molding surface. The transfer molding
surface is constituted by recessed transfer patterns corresponding
to the above-mentioned total of 16 grooves, protruded transfer
patterns corresponding to the alignment marks, and flat surfaces
formed in the peripheries thereof.
[0334] Two glass molded articles (optical element fixing member)
are press-molded by using the above-mentioned mold, and the optical
fibers are optically connected together by using these optical
element fixing members in the same manner as in Example 8. There
are obtained the same results as those of Example 8.
EXAMPLE 12
[0335] (1) Preparation of a First Mold by the Method cI.
[0336] First, a hard material containing WC is used as a mold
material. The mold material has the shape of a disk having a
diameter of 76.3 mm, a thickness of 2.0 mm and a maximum surface
roughness of 100 angstroms. Next, a positive-type photo-resist
(AZ1350 produced by Hoechst Co.) is applied by a spin-coating
method onto one surface of the mold material to form a resist film
52 having a thickness of 4.0 .mu.m on one surface of the mold
material 51 as shown in FIG. 8(a).
[0337] Next, a photomask of a predetermined shape is intimately
adhered onto the resist film 52, i.e., a photomask having
light-shielding portions, each light-shielding portions has a line
width of 12.5 .mu.m, of a predetermined pattern are intimately
adhered thereon so that the light-shielding portions are positioned
on the side of the resist film 52. Then, the resist film 52 is
exposed to ultraviolet ray (exposure of 25 mW/cm.sup.2) from the
side of the photomask, and is developed by being immersed in a
predetermined developing solution (AZ developer solution produced
by Hoechst Co.) for 90 seconds.
[0338] Through the developing, the exposed portions of the resist
film 52 are dissolved and removed, and resist patterns 53 of a
predetermined shape constituted by the portions that are not
exposed (portions that are not exposed to ultraviolet ray being
interrupted by the light-shielding portions formed on the
photomask) are formed in a predetermined number as shown in FIG.
8(b).
[0339] The resist patterns 53 are post-baked at 120.degree. C. for
60 minutes. Then, by using these resist patterns 53 as masks, one
surface of the mold material 51 is dry-etched for 10 minutes. The
dry-etching is effected by using a reactive etching apparatus of
the type of Inductively Coupled Plasma, and an Ar gas and a CF, gas
are used as etching gases. The etching conditions are the same as
the dry-etching conditions in Example 2(1).
[0340] Under the above-mentioned dry-etching conditions, the resist
patterns 53 are etched at a rate of 0.08 .mu.m/min, and the surface
of the mold material 51 of the side on where the resist patterns 53
are formed is etched at a rate of 0.03 .mu.m/min except the
portions that are protected by the resist patterns 53.
[0341] Then, the resist patterns are peeled off by using a
predetermined peeling solution to obtain a base member for a
desired first mold. Referring to FIG. 8(c), a predetermined number
of grooves 54a having a width of 12.5 .mu.m and a depth of 0.3
.mu.m are formed in a predetermined pattern in one surface of the
base member 54. In the base member 54, the surface of the side
where the grooves 54a are formed is serving as the transfer molding
bare surface 55.
[0342] Next, by using an RF sputtering apparatus, a mold release
film comprising Au, Pt and Ir is formed maintaining a thickness of
0.1 .mu.m on the transfer molding bare surface 55 of the base
member 54. The sputtering is effected by setting the atmosphere gas
(Ar gas) flow rate to be 20.0 sccm, the atmosphere pressure to be
1.0 Pa, and the RF bias to be 300 W.
[0343] Upon forming the mold release film, there is obtained a
first mold which is one of the molds CI of the present invention.
Referring to FIG. 8(d), the first mold 57 comprises the base member
54 and the mold release film 56 formed on the transfer molding bare
surface 55 of the base member 54, and the transfer patterns are
constituted by the transfer molding bare surface 55 and the mold
release film 56. The shape of the transfer molding bare surface 55
is reflected on the mold release film 56, and the surface 56a of
the mold release film 56 serves as the transfer molding surface of
the first mold 57.
[0344] (2) Preparation of a Second Mold.
[0345] A disk of a hard material containing WC having a diameter of
76.3 mm, a thickness of 2.0 mm and a maximum surface roughness of
100 angstroms is used as a base member for a second mold. A mold
release film having the same composition and the thickness as the
one formed at the time of preparing the first mold, is formed by
sputtering on one surface of the base member. Upon forming the mold
release film, there is obtained the second mold which, when
combined with the above-mentioned first mold, constitutes a set of
molds of the side-free type.
[0346] (3) Preparation of a Third Mold.
[0347] A block of a hard material containing WC is cut and polished
into a cylinder of a predetermined size to obtain a base member. A
mold release film having the same composition and the thickness as
those of the mold release film formed at the time of preparing the
first mold, is formed on the inner surface of the base member to
obtain a third mold which, when it is combined with the
above-mentioned first mold and the second mold, constitutes a set
of molds comprising three molds of an upper mold (the first mold or
the second mold), a lower mold (the second mold or the first mold)
and a sleeve mold (the third mold).
[0348] (4) Press-Molding.
[0349] First, a set of molds is constituted by using the first mold
prepared in (1) above and the second mold prepared in (2) above,
and the first mold is secured to an upper holder of a press molding
machine in a manner that the transfer molding surface thereof
becomes the lower surface, and the second mold is secured to a
lower holder of the press molding machine in a manner that the
transfer molding surface thereof becomes the upper surface. A mold
material of a soda lime glass (preform) of the shape of a disk
having a diameter of 60.0 mm and a thickness of 2.0 mm is placed on
the lower mold (the second mold), and the press-molding is effected
in vacuum under the conditions of an upper mold (the first mold)
temperature of 660.degree. C., a lower mold (the second mold)
temperature of 630.degree. C., a pressing force of 170 kg/cm.sup.2,
and a pressing time of 120 seconds, in order to obtain a
diffraction grating of the shape of a circular plate having a
diameter of 60.5 mm as viewed on a plane.
[0350] As schematically shown in FIG. 9, a total of 100 sets of
laminar grating portions 61 of a predetermined length including a
predetermined number of grooves of a width of 12.5 .mu.m and a
depth of 0.3 .mu.m maintaining a pitch of 25 .mu.m are formed in
one surface of the diffraction grating 60. The grooves constituting
the laminar grating portions 61 are formed maintaining a accuracy
of 12.5 .mu.m.+-.1% in width and 0.3 .mu.m.+-.3% in depth.
[0351] A diffraction grating same as the one mentioned above is
obtained by conducting the press-molding in the same manner as
described above with the exception of constituting a set of molds
using the above-mentioned first mold, second mold and third mold,
and using the first mold as the upper mold, using the second mold
as the lower mold and using the third mold as the sleeve mold.
EXAMPLE 13
[0352] (1) Preparation of a First Mold by the Method cII.
[0353] First, a hard material comprising chiefly WC without
containing binder component is used as the mold material. The mold
material has the shape of a flat plate measuring 50.0 mm long, 50.0
mm wide, 3.0 mm thick and having a maximum surface roughness of 80
angstroms. Next, a negative-type electron beam resist (ZEP7000
produced by Nippon Zeon Co.) is applied by a spin-coating method
onto one surface of the mold material to form a resin layer
maintaining a thickness of 1.3 .mu.m on one surface of the mold
material.
[0354] Next, by using an electron beam (exposure of 55
.mu.C/cm.sup.2), a predetermined number of ring patterns are drawn
on the resin layer. The resin layer after drawn with the electron
beam is developed by being immersed in a predetermined developing
solution (ZEP500 produced by Nippon Zeon Co.) for 90 seconds.
[0355] The portion of the resin layer that is not drawn with the
electron beam is dissolved and removed through the developing, and
the predetermined number of resist patterns comprising portions
drawn with the electron beam are formed.
[0356] The resist patterns are post-baked at 200.degree. C. for 30
minutes. By using these resist patterns as masks, one surface of
the mold material is dry-etched for 10 minutes. The dry-etching is
conducted by using a reactive etching apparatus of the type of
Inductively Coupled Plasma, and an Ar gas and a Cl.sub.2 gas are
used as etching gases. The etching conditions consist of a coil
bias of 600 W, a substrate bias of 300 W, an Ar gas flow rate of
30.0 sccm, a Cl.sub.2 gas flow rate of 10.0 sccm and a pressure of
5.0 mTorr.
[0357] Under the above-mentioned dry-etching conditions, the resist
patterns are etched at a rate of 0.06 .mu.m/min, and the surface of
the mold material of the side on where the resist patterns are
formed is etched at a rate of 0.02 .mu.m/min except the portions
that are protected by the resist patterns.
[0358] Thereafter, the resin patterns after dry-etching are peeled
off by using a predetermined peeling solution to obtain a base
member for a desired first mold. In one surface of the base member
are formed a predetermined number of annular grooves having a width
of 2.5 .mu.m and a depth of 0.2 .mu.m in a predetermined pattern.
In this base member, the surface of the side where the grooves are
formed serves as a transfer molding bare surface.
[0359] Next, by using an RF sputtering apparatus, a mold release
film comprising Au, Pt, Pd and Rh is formed maintaining a thickness
of 0.1 .mu.m on the transfer molding bare surface of the base
member. The sputtering is effected by setting the atmosphere gas
(Ar gas) flow rate to be 20.0 sccm, the atmosphere pressure to be
1.0 Pa, and the RF bias to be 300 W.
[0360] Upon forming the mold release film, there is obtained a
first mold which is one of the molds CI of the present invention.
The first mold comprises the base member and the mold release film,
and the transfer patterns are constituted by the transfer molding
bare surface and the mold release film. The shape of the transfer
molding bare surface is reflected on the mold release film, and the
surface of the mold release film serves as the transfer molding
surface of the first mold.
[0361] (2) Preparation of a Second Mold.
[0362] A flat plate of the same hard material as the one used as
the mold material in (1) above and measuring 50.0 mm long, 50.0 mm
wide, 3.0 mm thick and having a maximum surface roughness of 80
angstroms, is used as a base member for a second mold. A mold
release film having the same composition and the thickness as the
one formed at the time of preparing the first mold, is formed on
one surface of the base member by sputtering. Upon forming the mold
release film, there is obtained the second mold which, when
combined with the above-mentioned first mold, constitutes a set of
molds of the side-free type.
[0363] (3) Preparation of a Third Mold.
[0364] A block of the same hard material as the one used as the
mold material in (1) above is cut and polished into a cylinder of a
predetermined size to obtain a base member. A mold release film
having the same composition and the thickness as those of the mold
release film formed at the time of preparing the first mold, is
formed by sputtering on the inner surface of the base member to
obtain a third mold which, when it is combined with the
above-mentioned first mold and the second mold, constitutes a set
of molds comprising three molds of an upper mold (the first mold or
the second mold), a lower mold (the second mold or the first mold)
and a sleeve mold (the third mold).
[0365] (4) Press-Molding.
[0366] A zone plate of the shape of a rectangular flat plate
measuring 50.2.times.50.2 mm as viewed on a plane and having a
thickness of 1.9 mm is obtained by conducting the press-molding in
quite the same manner as in Example 12(4) with the exception of
constituting a set of molds using the first mold and the second
mold, using a preform of N5 (glass material produced by HOYA Co.)
measuring 50.0.times.50.0.times.2.0 mm and setting the pressing
force to be 160 kg/cm.sup.2.
[0367] As schematically shown in FIG. 10, a total of 64 ring
patterns 71 are formed like a matrix on one surface of the zone
plate 70. The ring patterns 71 are formed by a total of 100 annular
grooves 72 that are concentrically formed maintaining a
predetermined pitch, each annular groove 72 having a line width of
2.5 .mu.m and a depth of 0.2 .mu.m. The annular grooves 72
constituting the ring patterns 71 are formed maintaining a accuracy
of 2.5 .mu.m.+-.4% in width and 0.2 .mu.m.+-.3% in depth.
[0368] A zone plate same as the one mentioned above is obtained by
conducting the press-molding in the same manner as described above
with the exception of constituting a set of molds using the first
mold, second mold and third mold, and using the first mold as an
upper mold, using the second mold as a lower mold and using the
third mold as a sleeve mold.
EXAMPLE 14
[0369] (1) Preparation of a First Mold by the Method CII.
[0370] First, amorphous carbon is used as a mold material. The mold
material has the shape of a disk having a diameter of 76.3 mm, a
thickness of 2.0 mm and a maximum surface roughness of 120
angstroms. Next, a resist film is formed maintaining a thickness of
3.0 .mu.m on one surface of the mold material in the same manner as
in Example 12(1).
[0371] Next, a photomask of a predetermined shape is intimately
adhered onto the resist film, i.e., a photomask having
light-shielding portions, each light-shielding portions has a line
width of 30 .mu.m, of a predetermined pattern is intimately adhered
onto the resist film so that the light-shielding portions are
positioned on the side of the resist film. Then, the resist film is
exposed and is developed in the same manner as in Example 12(1),
and the predetermined number of resist patterns are formed.
[0372] The resist patterns are post-baked at 120.degree. C. for 60
minutes. Then, by using these resist patterns as masks, one surface
of the mold material is dry-etched for 5 minutes. The dry-etching
is effected by using a reactive etching apparatus of the type of
Inductively Coupled Plasma, and a CF, gas is used as the etching
gas. The etching conditions consist of a coil bias of 600 W, a
substrate bias of 300 W, a CF.sub.4 gas flow rate of 20.0 sccm and
a pressure of 5.0 mTorr.
[0373] Under the above-mentioned dry-etching conditions, the resist
patterns are etched at a rate of 0.55 .mu.m/min, and the surface of
the mold material of the side on where the resist patterns are
formed is etched at a rate of 0.08 .mu.m/min except the portions
that are protected by the resist patterns.
[0374] Then, the resist patterns after dry-etching are peeled off
by using a predetermined peeling solution to obtain a first mold
which is one of the molds CII of the present invention. A
predetermined number of grooves having a width of 30 .mu.m and a
depth of 0.4 .mu.m are formed in a predetermined pattern in one
surface of the first mold. In this mold, the surface of the side
where the grooves are formed is serving as the transfer molding
surface.
[0375] (2) Preparation of a Second Mold.
[0376] A block of amorphous carbon is cut and polished into a disk
having a diameter of 76.3 mm, a thickness of 2.0 mm and a maximum
surface roughness of 120 angstroms to obtain a second mold which,
when combined with the above-mentioned first mold, constitutes a
set of molds of the side-free type.
[0377] (3) Preparation of a Third Mold.
[0378] A block of amorphous carbon is cut and polished into a
cylinder of a predetermined size to obtain a third mold which, when
it is combined with the above-mentioned first mold and the second
mold, constitutes a set of molds comprising three molds of an upper
mold (the first mold or the second mold), a lower mold (the second
mold or the first mold) and a sleeve mold (the third mold).
[0379] (4) Press-Molding.
[0380] A diffraction grating of the shape of a circular flat plate
having a diameter of 60.0 mm as viewed on a plane is obtained by
conducting the press-molding in quite the same manner as in Example
12(4) with the exception of constituting a set of molds by using
the above-mentioned first mold and the second mold, setting the
upper mold (the first mold) temperature to be 670.degree. C., the
lower mold (the second mold) temperature to be 640.degree. C., and
the pressing force to be 160 kg/cm.sup.2.
[0381] On one surface of the diffraction grating are formed a total
of 50 sets of laminar grating portions of a predetermined length
constituted by a predetermined number of grooves having a width of
30 .mu.m and a depth of 0.4 .mu.m maintaining a pitch of 60 .mu.m.
The grooves constituting the laminar grating portions are formed
maintaining a accuracy of 30.0 .mu.m.+-.1% in width and 0.4
.mu.m.+-.3% in depth.
[0382] A diffraction grating same as the one mentioned above is
obtained by conducting the press-molding in the same manner as
described above with the exception of constituting a set of molds
using the above-mentioned first mold, second mold and third mold,
and using the first mold as the upper mold, using the second mold
as the lower mold and using the third mold as the sleeve mold.
EXAMPLE 15
[0383] (1) Preparation of a First Mold by the Method cII.
[0384] First, amorphous carbon is used as a mold material. The mold
material has the shape of a flat plate measuring 50.0 mm long, 50.0
mm wide, 2.0 mm thick and having a maximum surface roughness of 120
angstroms. Next, a resin layer is formed maintaining a thickness of
1.5 .mu.m on one surface of the mold material. Then, in the same
manner as in Example 13(1), ring patterns are drawn using an
electron beam, the resin layer after drawn with the electron beam
is developed to form a predetermined number of resist patterns, and
the resist patterns are post-baked.
[0385] Then, by using these resist patterns as masks, one surface
of the mold material is dry-etched for 10 minutes. The dry-etching
is effected by using a reactive etching apparatus of the type of
Inductively Coupled Plasma, and an Ar gas is used as the etching
gas. The etching conditions consist of a coil bias of 600 W, a
substrate bias of 300 W, an Ar gas flow rate of 20.0 sccm, and a
pressure of 5.0 mTorr.
[0386] Under the above-mentioned dry-etching conditions, the resist
patterns are etched at a rate of 0.11 .mu.m/min, and the surface of
the mold material of the side on where the resist patterns are
formed is etched at a rate of 0.09 .mu.m/min except the portions
that are protected by the resist patterns.
[0387] Then, the resist patterns are peeled off by using a
predetermined peeling solution to obtain a first mold which is one
of the molds CII of the present invention. A predetermined number
of annular grooves having a line width of 3.0 .mu.m and a depth of
0.9 .mu.m are formed in a predetermined pattern in one surface of
the first mold. In this mold, the surface of the side where the
grooves are formed is serving as the transfer molding surface.
[0388] (2) Preparation of a Second Mold.
[0389] A block of amorphous carbon is cut and polished into a flat
plate having a length of 50.0 mm, a width of 50.0 mm, a thickness
of 2.0 mm and a maximum surface roughness of 120 angstroms to
obtain a second mold which, when combined with the above-mentioned
first mold, constitutes a set of molds of the side-free type.
[0390] (3) Preparation of a Third Mold.
[0391] A block of amorphous carbon is cut and polished into a
cylinder of a predetermined size to obtain a third mold which, when
it is combined with the above-mentioned first mold and the second
mold, constitutes a set of molds comprising three molds of an upper
mold (the first mold or the second mold), a lower mold (the second
mold or the first mold) and a sleeve mold (the third mold).
[0392] (4) Press-Molding.
[0393] A zone plate of the shape of a rectangular flat plate
measuring 40.1.times.40.1 mm as viewed on a plane and having a
thickness of 1.9 mm is obtained by conducting the press-molding in
quite the same manner as in Example 13(4) with the exception of
constituting a set of molds using the first mold and the second
mold, using a preform of N5 (glass material produced by Hoya Co.)
of a size of 40.0.times.40.0.times.2.0 mm and setting the upper
mold (first mold) temperature to be 620.degree. C.
[0394] A total of 150 ring patterns are formed like a matrix on one
surface of the zone plate. The ring patterns are formed by a
predetermined number of annular grooves that are concentrically
formed maintaining a predetermined pitch, each annular groove
having a line width of 3.0 .mu.m and a depth of 0.9 .mu.m. The
annular grooves constituting the ring patterns are formed
maintaining a accuracy of 3.0 .mu.m.+-.3% in width and 0.9
.mu.m.+-.3% in depth.
[0395] A zone plate same as the one mentioned above is obtained by
conducting the press-molding in the same manner as described above
with the exception of constituting a set of molds using the first
mold, second mold and third mold, and using the first mold as an
upper mold, using the second mold as a lower mold and using the
third mold as a sleeve mold.
[0396] By using the mold A of the present invention as described
above by way of working examples, it is made possible to obtain, by
press-molding, a optical element fixing member and having alignment
marks at desired portions. Therefore, the optical element fixing
member are produced in large quantities and cheaply, making it
possible to optically connect together, in short periods of time;
the optical elements to be fixed or mounted or to optically connect
together the optical elements between the optical element fixing
members on which the optical elements have been fixed or
mounted.
[0397] The methods bI and bII of the present invention make it
possible to easily obtain a mold having a highly accurately formed
transfer molding surface constituted by transfer patterns of any
desired shape and, hence, to easily obtain, by press-molding, a
molded article on which ruggedness of a predetermined shape are
highly accurately formed like a optical element fixing member.
[0398] The molds CI and CII of the present invention is the one
which capable of easily obtaining molds having a transfer pattern
of a predetermined shape maintaining a high accuracy and featuring
a long life. Therefore, use of the mold CI or the mold CII makes it
possible to produce, by press-molding, glass molded articles such
as diffraction elements made of a glass at a further decreased
cost.
* * * * *