U.S. patent application number 10/758085 was filed with the patent office on 2004-09-02 for optical member and method of producing the same.
This patent application is currently assigned to KABUSHIKI KAISHA TOPCON. Invention is credited to Takahashi, Takashi.
Application Number | 20040168758 10/758085 |
Document ID | / |
Family ID | 32854119 |
Filed Date | 2004-09-02 |
United States Patent
Application |
20040168758 |
Kind Code |
A1 |
Takahashi, Takashi |
September 2, 2004 |
Optical member and method of producing the same
Abstract
A plurality of optical members (lenses) for use in ultraviolet
region are mutually stuck. A fluorine-based organic compound (for
example, fluorine-based oil) is provided between them. The
periphery of the optical members is sealed with a sealant. As the
sealant, an adhesive fluorine resin, for example, a soluble
fluorine resin is used.
Inventors: |
Takahashi, Takashi; (Tokyo,
JP) |
Correspondence
Address: |
FOLEY AND LARDNER
SUITE 500
3000 K STREET NW
WASHINGTON
DC
20007
US
|
Assignee: |
KABUSHIKI KAISHA TOPCON
|
Family ID: |
32854119 |
Appl. No.: |
10/758085 |
Filed: |
January 16, 2004 |
Current U.S.
Class: |
156/145 |
Current CPC
Class: |
G02B 3/12 20130101; G02B
1/14 20150115; G02B 1/105 20130101 |
Class at
Publication: |
156/145 |
International
Class: |
B32B 031/00; A63B
039/00; A63B 041/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 28, 2003 |
JP |
2003-053450 |
Mar 11, 2003 |
JP |
2003-064508 |
Jun 10, 2003 |
JP |
2003-165530 |
Claims
What is claimed is:
1. A method of producing an optical member, comprising steps of:
sticking a plurality of optical members for use in ultraviolet
region; filling a fluorine-based organic compound between the
optical members; and sealing the fluorine-based organic compound
with an adhesive fluorine resin at the periphery of the optical
members.
2. The method of producing an optical member according to claim 1,
wherein the fluorine-based organic compound is a fluorine-based
oil.
3. An optical member comprising: a plurality of mutually stuck
optical members for use in ultraviolet region; a fluorine-based
organic compound provided between the optical members; and a
fluorine resin for adhesively sealing the periphery of the
fluorine-based organic compound at the periphery of the optical
members.
4. The optical member according to claim 3, wherein the
fluorine-based organic compound is a fluorine-based oil.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an optical member for use
in ultraviolet region (for example, an optical member for use in a
transmitting optical system such as laminated lens or prism) and a
method of producing the same and, particularly, to an optical
member suitable for use in the ultraviolet region of a
semiconductor inspection device or the like and a method of
producing the same.
[0003] 2. Description of the Related Art
[0004] In conventional semiconductor inspection devices and other
accurate measuring devices, inspection of a wafer or the like has
been performed in an ultraviolet wavelength area of 200-400 nm, and
a quartz (SiO.sub.2)-made lens or a fluorite (CaF.sub.2)-made lens
is used in such semiconductor inspection devices for correction of
chromatic aberration (achromatization).
[0005] For example, as shown in Japanese Patent Application
Laid-Open No. 60-186444, it is known to protect the boundary part
of the adhesive surface of a prism type optically adhered beam
splitter for interferometer with the outside with a sealant.
[0006] An optical element having an adhesive member constituted as
a film having both a film thermal adhesive layer and a barrier
layer by using a thermally fusible film with high steam barrier
property such as fluorine-based film is known as shown in Japanese
Patent Application Laid-Open No. 2-287419, wherein CTFE
(polychlorotrifluoroethane), FEP (polyperfluoroethylene-propylene),
PVDF (polyvinylidene fluoride), PVDC (polyvinylidene chloride) and
the like are used as the material of the film.
[0007] Further, as shown in Japanese Patent Application Laid-Open
No. 60-176017, an optical element in which a rubber elastic body
such as ethylene propylene rubber or silicone rubber which is
transparent under visible light is put between two lenses which are
not closely fitted, and the rubber elastic body is covered with a
piezoelectric film such as polyvinylidene fluoride or the like is
known.
[0008] In Japanese Patent Application Laid-Open No. 5-2105, as the
material of an annular film constituting the film material, for
example, thermoplastic resins and thermosetting resins such as
polyethylene, polypropylene, polyvinyl chloride, polyamide,
polystyrene, polyisobutylene, polycarbonate, polyvinilydene
chloride, polyvinyl acetal, polymethyl methacrylate,
polyacrylonitrile, polyimide, cellulose-based fluorine resin,
epoxy, polyurethane, silicone resin; copolymers thereof, and those
with plasticizer or filler added thereto are used.
[0009] As shown in Japanese Patent Laid-Open No. 2003-12349, a
joined optical element for UV region is also known, which is formed
through an adhesive layer by joining optical elements capable of
transmitting ultraviolet rays, using as the adhesive layer a
solution in which a solvent-soluble organic fluorine resin having
no unsaturated bond in the molecule is dissolved in a
fluorine-containing solvent having a boiling point of 150.degree.
C. or higher and containing no unsaturated bond in the molecule,
vaporizing the solvent in the part in contact with atmosphere of
the adhesive layer, and joining the optical elements in the state
where the solvent in the other part is left in the adhesive
layer.
[0010] The adhesion by use of a conventional sealant had problems
as that the inside solvent is not hardened because it is not
vaporized due to large adhesion distortion, a heating treatment
cannot be performed because it affects a high precision lens, and
an axial slippage is caused. Therefore, an extremely precise device
such as semiconductor inspection device could not be suitably used
in ultraviolet region.
SUMMARY OF THE INVENTION
[0011] In consideration of the above problems, the present
invention thus has an object to provide an optical member sealed
with a sealant never deteriorated by UV absorption and capable of
precisely mutually bonding optical elements or the like and a
method of producing the same.
[0012] Preferred modes of the present invention are then
described.
[0013] A plurality of optical members for use in ultraviolet region
are closely fitted and stuck together. A fluorine-based organic
compound is filled between the optical members. The periphery of
the fluorine-based organic compound is sealed with an adhesive
fluorine resin, e.g., a soluble fluorine resin in the periphery of
the optical members.
[0014] A preferred sealant is a sealant which is never deteriorated
by ultraviolet absorption, causes no adhesion distortion when
covering the optical elements, so that the inside solvent can be
easily vaporized and hardened without requiring a heating
treatment, nor axial slippage. As the most suitable material to be
filled in the optical elements for use in ultraviolet region, a
fluorine-based organic compound is adapted. A preferred example of
the fluorine-based organic compound is a fluorine-based oil
(fluorine grease).
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a schematic sectional view of an optical member
according to one embodiment of the present invention; and
[0016] FIG. 2 is a schematic sectional view of an optical member
according to the other embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0017] The present invention will be further described in reference
to the drawings.
[0018] FIG. 1 shows an optical member according to one embodiment
of the present invention.
[0019] In FIG. 1, the optical member comprises two lenses 1 and 2
for use in ultraviolet region.
[0020] The lens 1 is a lens formed of a fluorite (CaF.sub.2) about
20 mm in diameter, and the lens 2 is a lens formed of a synthetic
quartz (SiO.sub.2) about 20 mm in diameter. A gap entirely having
the same thickness is preferably provided between the lenses 1 and
2. A fluorine grease 3 that is one preferred example of the
fluorine-based organic compound is perfectly filled in the gap.
Consequently, the lenses 1 and 2 are mutually closely fitted and
stuck.
[0021] The dimension of the gap between the lenses in FIG. 1 is set
to 10-20 .mu.m.
[0022] The profile irregularities of the fluorite (CaF.sub.2) lens
1 and the synthetic quartz (SiO.sub.2) lens 2 are, for example,
about 1/20 .lambda., wherein .lambda. shows a standard wavelength,
and it is set, as described later, to a wavelength of transmitted
ultraviolet rays 200-300 nm, for example, 248 nm.
[0023] A wavelength of 100-200 nm, for example, 193 nm is also
possible depending on the power of laser.
[0024] The fluorine grease 3 has durability to an excimer laser
such as KrF laser described later.
[0025] As the fluorine grease 3, various ones are usable.
Particularly, the fluorine greases described below are preferably
used. However, the present invention is never limited by them.
[0026] It was found that, when the lenses 1 and 2 stuck as shown in
FIG. 2 are irradiated with a high luminance ultraviolet ray having
a short wavelength of 200 nm or less, the surface of the synthetic
quartz lenses 1 and 2 in contact with the fluorine-based grease 3
as the fluorine oil are roughed. The roughing of the surface of the
synthetic quartz lenses 1 and 2 can be prevented by evaporating
fluorides 5, 6 such as magnesium fluoride on the surface of the
synthetic quartz lenses 1 and 2.
EXAMPLE 1
[0027] Fluorine grease produced by Daikin Industries Ltd. (trade
name: DEMNUM Series) 1
EXAMPLE 2
[0028] Fluorine grease produced by E.I. du Pont de Nemours &
Company 2
EXAMPLE 3
[0029] Fluorine grease produced by Solvay S.A. (trade name;
FOMBLINY) 3
CF.sub.3O--CF.sub.2--CF.sub.2.paren close-st.O--CF.sub.2.paren
close-st..sub.qO--CF.sub.3
[0030] In the embodiment of FIG. 1, the fluorine grease produced by
Daikin Industries, Ltd. is used.
[0031] In the state after the fluorine grease 3 is filled between
the lenses 1 and 2, the total thickness of the fluorite (CaF.sub.2)
lens 1, the fluorine grease 3, and the synthetic quartz (SiO.sub.2)
lens 2 is about 5 mm although it is exaggerated in FIG. 1.
[0032] As shown in FIGS. 1 and 2, after the fluorine grease 3 is
filled in the gap between the fluorite (CaF.sub.2) lens 1 and the
synthetic quartz (SiO.sub.2) lens 2, the whole periphery of the
lenses 1 and 2 is sealed with a sealant 4.
[0033] As the sealant 4, for example, organic solvent-soluble
amorphous fluorine resins such as CYTOP (trade name, produced by
Asahi Glass Co., Ltd.), TEFLON (registered trademark), AF Series
(trade name, produced by Du Pont-Mitsui Fluorochemicals Company,
Ltd.), ALGOFLON AD series (trade name, Solvay Solexis K.K.),
INT-444V (trade name, produced by NI material), and other products
produced by Hoechst AG and Mitsubishi Rayon Co., Ltd. can be used.
In this case, the fluorite (CaF.sub.2) lens 1 and the synthetic
quartz (SiO.sub.2) lens 2 can be more firmly bonded, and the leak
of the fluorine grease 3 from the periphery of the gap between the
lenses 1 and 2 can be surely prevented.
[0034] In addition to these fluorine-based oils, as the same
fluorine-based organic compounds, AFLUDE (trade name, produced by
Asahi Glass Co., Ltd.), other perfluorocarbons (PFC, produced by 3M
Company and E.I. du Pont de Nemours & Company),
hydrofluorocarbons (HFC), hydrofluoroether (HFE), DEMNUM (produced
by Daikin Industries, Ltd.), FOMBLIN (produced by Solvay AG),
KRYTOX (produced by E.I. du Pont de Nemours & Company) and
others can be also used for the production of an optical member for
use in ultraviolet region.
[0035] [Experiment]
[0036] An optical member was produced by sticking two lenses 1 and
2 as shown in FIG. 1. The optical member was irradiated with an
excimer laser such as KrF laser of deep UV 248 nm from a general
direction at an output of 3 W/cm.sup.2 for 148 hours. The optical
thickness of the fluorine grease 3 was 10 .mu.m, but the
transmittance of the fluorine grease 3 was hardly changed. Adhesion
distortion was hardly observed.
[0037] [Comparative Experiment]
[0038] An optical member having the same shape and dimension as the
optical member used in the above experiment (e.g., the same
diameter, thickness and clearance between lenses 1 and 2) was
produced by performing the adhesion of fluorite (CaF.sub.2) lens
and synthetic quartz (SiO.sub.2) lens by use of an adhesive
consisting of an organic silicone resin of SILPOT 184 produced by
Dow Corning Corp. instead of filling the fluorine grease 3 in the
gap between the lenses 1 and 2. The optical member for comparative
experiment was irradiated with an excimer laser such as KrF laser
of deep UV region 248 nm at an output of 3 W/cm.sup.2 for 148 hours
similarly to the above experiment. Consequently, the layer formed
by the adhesive consisting of the organic silicone resin of SILPOT
184 produced by Dow Corning Corp. was peeled as it is burnt off by
the laser beam of the excimer laser, and deteriorated. Adhesion
distortion was also caused to deteriorate the characteristics of
the optical member.
[0039] According to the present invention, a plurality of lenses
can be further firmly and precisely joined, and the leak from the
periphery of the gap between the lenses can be surely prevented.
Further, the deterioration by UV absorption can be also
avoided.
* * * * *