JP3198673B2 - Manufacturing method of fly-eye lens - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flywheel for converting light having non-uniform illuminance into light having uniform illuminance, which is used in an optical system requiring uniform illuminance, for example, in an optical device such as a semiconductor manufacturing apparatus. The present invention relates to a method for manufacturing an eye lens.

[0002]

2. Description of the Related Art An integrated circuit (I) is formed on a wafer such as silicon.
In the photolithography technique for exposing and transferring the fine pattern of C), an exposure apparatus (semiconductor manufacturing apparatus) called a stepper is used. In general, a plurality of secondary light sources are formed in an illumination system of a stepper to illuminate an object surface (mask surface) with a large number of light beams to remove a diffraction image by a mask and to obtain uniform illumination without unevenness. A fly-eye lens is used. Optical materials for fly-eye lenses include borosilicate crown glass, phosphate glass, and KrF having a wavelength shorter than i-line (365 nm).
(248 nm) and ArF (193 nm) excimer lasers, synthetic quartz glass or C
A single crystal of fluoride such as aF ₂ (fluorite) is used.

Conventionally, a fly-eye lens has been manufactured by manufacturing square rod-shaped convex lenses one by one as shown in FIG. 8 and bonding the individual lenses with an adhesive as shown in FIG.
It was manufactured by a method of forming a convex aggregate.

[0004]

However, in the conventional manufacturing method as described above, since each of the rectangular rod-shaped convex lenses is manufactured one by one, the length of each lens varies, and the lens is formed by bonding. There is a problem that the height of each convex surface of the formed convex surface aggregate becomes non-uniform, thereby deteriorating the optical performance as a fly-eye lens.

[0005] Also, in order to bond individual lenses,
The shrinkage of the adhesive used for bonding when the adhesive is cured causes the lens to be pulled and a large distortion to occur, which causes a problem that the optical performance of the fly-eye lens deteriorates. In addition, when the optical system is actually used for a long time after being incorporated into an optical system, there is a problem that the bonding accuracy of individual lenses is reduced due to deterioration of the adhesive due to absorption of light.

In addition, since each square rod-shaped lens is manufactured by high-precision polishing, there is a problem that the processing requires a long time, resulting in a very expensive fly-eye lens. An object of the present invention is to solve such a problem and to provide a highly accurate and inexpensive method for manufacturing a fly-eye lens.

[0007]

The inventors of the present invention have conducted intensive studies, and as a result, in order to form such an aggregate of convex surfaces, the upper and lower concave patterns composed of a plurality of concave surfaces were heated and softened. It has been found that the above problem can be solved by transferring the pressure to the optical glass material while the air is exhausted , and the present invention has been accomplished.

Accordingly, the present invention firstly comprises a step of heating and softening an optical glass material, and a step of transferring the softened optical glass material between a pair of upper and lower dies having a plurality of concave patterns polished with high precision. And a step of transferring the upper and lower mold patterns onto the softened optical glass material under pressure while air is exhausted (first invention).

In the second aspect of the present invention, a step of arranging an optical glass material between a pair of upper and lower dies having a plurality of highly polished concave patterns, and holding the optical glass material in a state where air is exhausted . A method of manufacturing a fly-eye lens, comprising: a step of softening the optical material by heating the upper and lower molds; and a step of transferring the pattern of the upper and lower molds under pressure to the softened optical material while air is exhausted. (Second invention).

[0010]

According to the present invention, first, the upper and lower molds having a plurality of concave surfaces are made of tungsten carbide, high-speed steel, ceramics, etc., and can be polished with high precision. Is extremely small, and the convex pattern press-transferred from the upper and lower molds can be manufactured with high precision without the conventional height variation.

Since there is no need to bond with an adhesive as in the prior art, there is no inconvenience such as generation of distortion due to shrinkage during curing of the adhesive and deterioration of the adhesive due to light absorption. Furthermore, in order to manufacture a convex pattern by a method of pressing and transferring a vertical concave pattern having a plurality of high-precision polished concave surfaces, it does not require a long processing time as in the related art, and is manufactured in an extremely short time. be able to.

In the step of heating and softening the optical glass material, the heating temperature range varies depending on the optical glass material.
The temperature is preferably from 00 ° C to 1200 ° C to 1250 ° C for quartz glass. In general, when the heating temperature is set to be higher and a mold such as high-speed steel is used as the upper and lower molds, there is an advantage that the cost of the equipment and the upper and lower molds can be reduced. When the heating temperature is set lower and a mold made of cemented carbide such as tungsten carbide is used as the upper and lower molds, there is an advantage that a highly accurate fly-eye lens can be obtained.

[0013] In the step of pressure transferring the upper and lower molds of the concave pattern softened optical glass material, the pressure of the pressurization 20kgf / cm ² ~100kgf / cm ² is preferably about.
Hereinafter, the first invention and the second invention will be described in detail using examples, but the present invention is not limited thereto.

[0014]

[0015]

[0016]

Embodiment 2 A first embodiment of the second invention will be described with reference to FIGS. Square 50mm × 5 as shown in FIG.
A borosilicate crown glass (optical glass material) 1 polished on both sides to a thickness of 0 mm and a thickness of 20 mm is divided into 25 pieces of 10 mm × 10 mm, each of which has a plurality of finished surfaces each of which is concavely polished to R8 mm. Lower mold 3
And placed in the outer mold (sleeve) 4. The optical glass material 1, the upper mold 2, the lower mold 3, and the sleeve 4, which have been set, are placed as a work 5 in the apparatus shown in FIG. The valve 16 is opened, and the chamber 18 is roughly evacuated by the oil rotary pump 12. After the rough evacuation, the valve 16 is closed, the valves 14 and 15 are opened, and the main evacuation is performed by the oil diffusion pump 13. When the degree of vacuum of the vacuum gauge 19 becomes 5 × 10 ⁻⁵ Torr or less, heating by the heater 8 is started according to the schedule of FIG. Temperature 30
Then, the temperature is raised to 650 ° C. in minutes, and the temperature is maintained at 650 ° C. for 10 minutes. Five minutes after the start of the pressurization, the pressurization by the heater 8 is completed, and the temperature is lowered. At the end of pressurization, the temperature is 550 ° C. or less. Then, let it cool down.
Is closed, and the leak valve 17 is opened to introduce air. After introducing the atmosphere, the work 5 is taken out, and the upper mold 2 and the lower mold 3 are removed to complete a fly-eye lens as shown in FIG. The accuracy of each convex surface of the completed fly-eye lens is determined by the surface roughness R
Max 9nm or less, dispersion of spherical Newton ring ±
Two or less. The height variation of each convex surface was ± 1 μm or less.

The manufactured fly-eye lens was incorporated into an actual optical system, and the performance was evaluated. As a result, the optical performance was greatly improved as compared with the conventional product.

[0018]

Third Embodiment A second embodiment of the second invention will be described with reference to FIGS. Square 25mm x 2 as shown in Figure 2
A ceramic upper mold 2 and a lower mold 3 each having a plurality of finished surfaces each of which is a quartz glass (optical glass material) 1 having a thickness of 5 mm and a thickness of 15 mm, and each of which is polished to 25 mm into 5 mm × 5 mm and each having a concave surface of R6 mm. And placed in the sleeve 4. This quartz glass 1, upper mold 2,
The apparatus in which the lower mold 3 and the sleeve 4 are set is placed as a work 5 in the apparatus shown in FIG. The valve 16 is opened, and the chamber 1 is rotated by the oil rotary pump 12.
8 is roughly drawn. After the rough evacuation, the valve 16 is closed, the valves 14 and 15 are opened, and the main evacuation is performed by the oil diffusion pump 13. When the degree of vacuum of the vacuum gauge 19 becomes 5 × 10 ⁻⁵ Torr or less, heating by the heater 8 is started according to the heating schedule of FIG. The temperature is increased to 1200 ° C. in 50 minutes and maintained at 1200 ° C. for 10 minutes, and then the cylinder 10 is operated and pressurized for 10 minutes. Five minutes after the start of the pressurization, the heating by the heater 8 is completed, and the temperature is lowered. At the end of pressurization, the temperature is lower than 1000 ° C. After that, it is left to cool, and when the temperature reaches room temperature, the valve 15 is closed.
Open 7 and introduce air. After the work 5 is introduced into the atmosphere, the upper mold 2 and the lower mold 3 are removed, and a fly-eye lens as shown in FIG. 3 is completed. Convex surface 1 of completed fly-eye lens
The accuracy of each piece was a surface roughness Rmax of 9 nm or less, and the dispersion of spherical Newton rings was ± 2 or less. Also,
The height variation of each convex surface was ± 1 μm or less.

When the manufactured fly-eye lens was incorporated into an actual optical system and its performance was evaluated, the optical performance was greatly improved as compared with the conventional product.

[0020]

As described above, according to the manufacturing method of the present invention, a fly-eye lens having a plurality of optically functional surfaces can be manufactured with high precision. Has very high performance. In addition, since it can be manufactured without using an adhesive, there is no distortion due to shrinkage when the adhesive is cured, and there is no deterioration of the adhesive due to light absorption, so it has no performance even after long-term use There is also an effect that there is no decrease.

Furthermore, the drastic reduction of the processing time has made it possible to supply a very expensive fly-eye lens at a very low price.

[Brief description of the drawings]

FIG. 1 is a sectional view of a method for manufacturing a fly-eye lens according to the present invention.

FIG. 2 is a top view and a side view of an optical glass material used in the present invention.

FIG. 3 is a top view and a side view of a fly-eye lens manufactured according to the present invention.

FIG. 4 is a schematic view of a manufacturing apparatus used in the present invention.

FIG. 5 is a heating schedule diagram of Example 2.

FIG. 6 is a heating schedule diagram of Example 3.

FIG. 7 is a top view and a side view of a fly-eye lens manufactured by a conventional manufacturing method.

FIG. 8 is a top view and a side view of a single convex lens for bonding used in a conventional method for manufacturing a fly-eye lens.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Optical glass material 2 ... Upper mold 3 ... Lower mold 4 ... Outer mold (sleeve) 5 ... Work 6 ... Mounting stand 7 ... Press shaft 8 ... Heater 9 ... Insulation plate 10 ... Cylinder 11 ... Main body 12 ... Oil rotary pump 13 ... Oil diffusion pump 14 ... Valve 15 ... Valve 16 ... Valve 17 ... Leak Valve 18 ・ ・ ・ Chamber 19 ・ ・ ・ Vacuum gauge 20 ・ ・ ・ Adhesive

────────────────────────────────────────────────── (5) References JP-A-4-114924 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C03B 9/00-17/06 C03B 19 / 00-19/10

Claims (2)

(57) [Claims] 1. A step of heating and softening an optical glass material, a step of transferring the softened optical glass material between a pair of upper and lower molds having a plurality of highly polished concave patterns, and Pressurizing and transferring the air to the softened optical glass material in a state where air is exhausted . 2. A step of arranging an optical glass material between a pair of upper and lower molds having a plurality of highly polished concave patterns, and heating the upper and lower molds holding the optical glass material in a state where air is exhausted. A process of softening the optical glass material, and a step of press-transferring the upper and lower mold patterns onto the softened optical glass material in a state where air is exhausted .