JP3230346B2 - Apparatus and method for manufacturing quartz glass - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for manufacturing quartz glass, and particularly to a field requiring a quartz glass member requiring high homogeneity, such as optical lithography, a high-precision spectroscope, and the like. The present invention relates to a manufacturing apparatus and a manufacturing method of highly uniform quartz glass useful for precision optical instruments such as lasers.

[0002]

2. Description of the Related Art Conventionally, in an optical lithography technique for exposing and transferring a fine pattern of an integrated circuit onto a wafer such as silicon, an exposure apparatus called a stepper is used. The light source of this stepper has been changed from g-line (436 nm) to i-line (365n) with the recent high integration of LSI.
m), KrF (248 nm) and ArF (193 nm).
nm) Excimer lasers are being shortened in wavelength.

In general, optical glass used as an illumination system or a projection lens of a stepper has a low light transmittance in a wavelength region shorter than the i-line, so that synthetic quartz glass or CaF ₂ (fluorite) is used instead of the conventional optical glass. It has been proposed to use a fluoride single crystal such as Synthetic quartz glass used for the optical system of such a stepper is required to have a large diameter, high transmittance in the ultraviolet region, and high homogeneity in refractive index.

As one method of producing synthetic quartz glass, a silicon compound such as silicon tetrachloride (a carrier gas for sending out a silicon compound is used at the same time) as a raw material of quartz glass and a combustion gas (oxygen gas) for heating and reacting. And hydrogen gas) flow out of the burner to form SiO ₂ fine particles, deposit them on a target, and at the same time melt vitrify in a flame to obtain synthetic quartz glass.
The so-called gas phase reaction synthesis method (also called flame hydrolysis synthesis method) is employed.

[0005]

However, in a conventional apparatus for producing quartz glass by a gas phase reaction synthesis method, the homogeneity of the refractive index of quartz glass is not yet sufficient, and a further improvement is required. An object of the present invention is to stably produce quartz glass having a good refractive index homogeneity.

[0006]

In order to produce quartz glass having high homogeneity, it is ideal that all the central axes of the burner and the target of the production apparatus and the furnace are aligned. The reason is considered as follows. In a furnace or in a combustion flame by a burner, a large concentration of reactants SiCl ₄ , H ₂ , O ₂ and reaction products SiO ₂ , H ₂ O, HCl, and intermediates during the reaction, etc. There is a distribution and the temperature distribution is large. Therefore, if the positional relationship between the burner, target and furnace is different, synthesis will be performed in an environment with different concentrations and temperatures, and even if the other conditions are the same, the quality, especially homogeneity, of the synthesized quartz glass will be different. It is natural to come.

Nevertheless, the present inventors have examined the positional relationship between them, and found that, in the conventional manufacturing apparatus, the positions of the center axis of the burner and the target and the furnace were visually adjusted, so that the manufacturing was performed every time. Thus, it was found that the positional relationship was varied, and this was one of the causes of the deterioration of the uniformity of the refractive index. The alignment accuracy of the conventional manufacturing apparatus was about ± 5 mm.

[0008] Further, as in Japanese Patent Application No. 5-22294 filed earlier, a reference position is required for controlling the positional relationship between a burner, a target and a furnace in order to improve homogeneity. Becomes Furthermore, even if positioning is performed before manufacturing, the positional relationship is not always maintained during manufacturing, and the positioning accuracy may decrease due to expansion of the support portion of the burner due to temperature change and the like.

[0009] Therefore, as a result of further research to reproduce the positional relationship for each production and to stably produce quartz glass having good refractive index homogeneity while maintaining the positional relationship during production, It has been found that by providing the apparatus with positioning means serving as a reference for aligning the center axis of each of the burner and the target with the furnace, it is possible to reproduce the positional relationship for each production.

Therefore, the present invention provides an apparatus for producing quartz glass comprising a furnace, a target for forming an ingot installed inside the furnace, and a burner for synthesizing quartz glass which is installed with its tip facing the target. , A positioning apparatus for positioning the center axis of each of the target and the burner with the furnace is provided.

As the positioning means of the present invention, for example, by using an optical axis of a laser beam fixed to a floor in a furnace, an absolute reference axis capable of reproducing a positional relationship for each production is obtained. be able to. Further, as a positioning means during manufacturing, for example, a mirror fixed to the burner is irradiated with laser light to measure the position of the reflected light, and the position of the burner is adjusted accordingly, whereby the positional relationship during manufacturing can be maintained. .

[0012]

In the conventional quartz glass manufacturing apparatus, since the burner is mounted in the burner hole of the furnace (refractory) by visual alignment, the direction of the flame is not constant and the reproducibility is low. In the quartz glass manufacturing apparatus of the present invention, the quartz glass can be manufactured with good reproducibility without being shifted every time by using the optical axis of the laser fixed to the floor as a reference axis for alignment. .

Further, since the furnace, burner and target are exposed to extremely high temperatures during the production of quartz glass, the positions are maintained during the production even if the center axes of the furnace, burner and target are adjusted before synthesis. Was not guaranteed and could have shifted. In the apparatus for manufacturing quartz glass of the present invention, a mirror is fixed to a burner, a laser beam is applied to the mirror, the position of the reflected laser beam is measured, and the position of the burner is adjusted accordingly. Maintain the positional relationship.

According to the present invention, the positioning accuracy which was conventionally about ± 5 mm is improved to 1 mm or less. Quartz glass with improved refractive index homogeneity produced by the quartz glass production apparatus of the present invention is mainly a lens, a prism,
It is used as a base material of an optical element such as a reflector. The outer peripheral portion of the manufactured quartz glass is cut off, cut and reshaped as required, and processed into an arbitrary shape. After being annealed (heat-treated) to eliminate internal strain, the optical element becomes an optical element through polishing and coating steps.

[0015]

Example 1 An optical system for collimation was installed at the exit of a He-Ne laser or a semiconductor laser to obtain a laser beam having a beam diameter of 2.0 mm and a divergence angle of 0.5 mrad or less. By fixing these laser optical systems to the floor in the synthesis furnace room, a reference optical axis whose position did not fluctuate in each synthesis was obtained. The synthesis furnace was arranged so that the reference optical axis was the center axis, and the burner and the center axis of the target were arranged so that the laser light passed through the center tube provided in the center tube of the burner and the substrate rotation axis. (Figure 1)
The accuracy, which was visually ± several mm, has been improved to ± 0.2 mm.

[0016]

Embodiment 2 A mirror is fixed to a burner as shown in FIG.
He-Ne laser or semiconductor laser light installed in the furnace chamber was applied to a mirror, and the position of the reflected light was detected by a two-dimensional position detector. The position adjusted before the combining was set as the origin, and when the position of the reflected light deviated from the origin during the combining, the inclination of the burner was adjusted by the controller so as to return to the reflected light position origin.

[0017]

According to the present invention, the positioning accuracy and reproducibility between the center axis of the burner and the target and the furnace are improved,
Further, since the positional relationship during manufacture is maintained, quartz glass having excellent characteristics, for example, good homogeneity can be stably manufactured with good reproducibility.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a first embodiment of the present invention.

FIG. 2 is a conceptual diagram of a second embodiment of the present invention.

Continuation of the front page (72) Inventor Hiroyuki Hiraiwa 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Examiner, Nikon Corporation Mitsuchi Chino (56) References JP-A-61-186241 (JP, A) JP-A Sho 59-174537 (JP, A) JP-A-59-169950 (JP, A) JP-A-56-96740 (JP, A) Japanese Utility Model Laid-Open No. 58-121337 (JP, U) (58) Fields investigated (Int. Cl. ^7, DB name) C03B 8/04 C03B 37/018

Claims (6)

(57) [Claims] And 1. A furnace chamber, and the target for ingot formation installed inside the furnace chamber, the apparatus for manufacturing a quartz glass comprising a burner for installation quartz glass synthesis toward the tip to the target, Laser light on floor in furnace chamber
The optical system is fixed, and the laser light from the laser
Central axes of target and burner as quasi-optical axes
And a center of the furnace chamber . 2. A quartz glass manufacturing apparatus according to claim 1, wherein the burner emits laser light from a laser optical system.
Fix the mirror that reflects the light, and adjust the position of the reflected laser light.
A quartz glass manufacturing apparatus, wherein the alignment is performed by measuring the position . 3. The quartz glass manufacturing apparatus according to claim 1 , wherein the positioning accuracy is ± 1.
An apparatus for manufacturing quartz glass, characterized in that the diameter is equal to or less than mm. 4. A furnace chamber and an ingot installed inside the furnace chamber.
And a tip for forming the target
Composed of a quartz glass burner and a stone burner
Using a British glass manufacturing equipment, siliconization from the burner
Compound gas, oxygen gas and hydrogen gas are spouted and burned,
Deposit quartz glass on target to form ingot
Laser glass on the floor in the furnace chamber
-Fix the optics and apply the laser
The laser beam from the optical system is
And the center axis of each burner and the center of the furnace chamber
A method for producing quartz glass. 5. The method for producing quartz glass according to claim 4, wherein the burner emits laser light from a laser optical system.
Fix the mirror that reflects light, and
Measuring the position of the laser beam reflected by the
By adjusting the position of the burner according to the measured value
A method for producing quartz glass, which comprises performing alignment. 6. The method for manufacturing quartz glass according to claim 4 , wherein the accuracy of the alignment is ± 1.
A method for producing quartz glass, which is not more than mm.