JPH0753226A - Apparatus and method for producing quartz glass - Google Patents

Abstract

PURPOSE:To stably synthesize a quartz glass having good homogeneity of refractive indices by a vapor phase reaction synthesis method. CONSTITUTION:The burner and target of the apparatus for production and a furnace are aligned by using aligning means for aligning the respective central axes of the burner and the target and the position of the furnace, for example, the optical axis of a laser beam fixed to the floor in the furnace, thereby, the positional relation at every production can be reproduced and the positional relation during production can be maintained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a quartz glass manufacturing apparatus and method, and particularly to a field requiring a quartz glass member requiring high homogeneity, for example, photolithography, high precision spectrometer, The present invention relates to an apparatus and method for producing highly homogeneous quartz glass that is useful for precision optical instruments such as lasers.

[0002]

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

Generally, 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 i-line. Therefore, synthetic quartz glass or CaF2 (fluorite) is used instead of conventional optical glass. It has been proposed to use a single crystal of fluoride. The synthetic quartz glass used in the optical system of such a stepper is required to have a large diameter, a high transmittance in the ultraviolet region, and a high homogeneity of the refractive index.

As one of the methods for 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) which is a raw material of quartz glass and a combustion gas (oxygen gas) for heating / reaction. And hydrogen gas) are discharged from the burner to form SiO2 fine particles, which are deposited on the target and simultaneously vitrified in a flame to obtain synthetic quartz glass.
The so-called gas-phase reaction synthesis method (also called flame hydrolysis synthesis method) is adopted.

[0005]

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

[0006]

In order to manufacture highly homogeneous quartz glass, it is ideal that the central axes of the burner and target of the manufacturing apparatus and the furnace are all aligned. The reason for this is considered as follows. In the furnace or in the combustion flame by the burner, there are large concentration distributions of the reaction materials SiCl4, H2, O2 and reaction products SiO2, H2O, HCl, and intermediates in the middle of the reaction. The distribution is also large. Therefore, if the positional relationship among the burner, target, and furnace is different, the synthesis will be performed in the environment where the concentration and temperature are different, and even if the other conditions are the same, the quality of the synthesized silica glass, especially the homogeneity, will differ. It is natural to come.

Despite this, the inventors of the present invention investigated the positional relationship between them, and found that in the conventional manufacturing apparatus, since the positions of the burner and the center axis of the target and the furnace were visually aligned, the manufacturing was performed every time. It was found that the positional relationship was different, which was one of the causes of deterioration of the homogeneity of the refractive index. The alignment accuracy of the conventional manufacturing apparatus was about ± 5 mm.

Further, as in Japanese Patent Application No. Hei 5-22294 filed earlier, a reference position as an original is required when controlling the positional relationship between the burner, the target and the furnace in order to improve the homogeneity. Becomes Further, even if the positioning is performed before the manufacturing, the positional relationship is not always maintained during the manufacturing, and the positioning accuracy may be deteriorated due to the expansion of the supporting portion of the burner due to the temperature change.

Therefore, as a result of further research in order to stably manufacture silica glass having good homogeneity of refractive index by reproducing the positional relationship during each manufacturing and maintaining the positional relationship during manufacturing, It has been found that the positional relationship for each production can be reproduced by providing the apparatus with positioning means serving as a reference for aligning the central axes of the burner and the target with the furnace.

Therefore, the present invention is an apparatus for producing silica glass, which comprises a furnace, an ingot-forming target installed inside the furnace, and a burner for synthesizing silica glass, the tip of which is directed toward the target. In the above, there is provided an apparatus for producing quartz glass, which has a central axis of each of the target and the burner, and positioning means for aligning with the furnace.

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

[0012]

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

Further, since the furnace, the burner and the target are exposed to extremely high temperatures during the production of the quartz glass, even if the central axes of the furnace, the burner and the target are adjusted before the synthesis, the positions are maintained during the production. It was not guaranteed that there was a deviation. In the quartz glass manufacturing apparatus of the present invention, a mirror is fixed to the burner, laser light is applied to this mirror, the position of the reflected laser light is measured, and the position of the burner is adjusted in accordance with the position of the manufacturing process. Hold the positional relationship.

According to the present invention, the alignment accuracy, which was about ± 5 mm in the past, is improved to 1 mm or less. The quartz glass with improved homogeneity of the refractive index manufactured by the quartz glass manufacturing apparatus of the present invention is mainly composed of a lens, a prism,
Used as a base material for optical elements such as reflectors. The outer peripheral portion of the manufactured quartz glass is scraped off, cut and re-formed as necessary to be processed into an arbitrary shape. Then, after being annealed (heat-treated) to eliminate internal strain, an optical element is obtained 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 chamber, a reference optical axis whose position did not change was obtained in each synthesis. The synthesis furnace was arranged so that the reference optical axis became the central axis, and the central axes of the burner and the target were arranged so that the laser beam could pass through the central tube of the burner and the central hole provided in the substrate rotation axis. (Fig. 1)
The accuracy, which was ± several mm visually, was improved to ± 0.2 mm.

[0016]

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

[0017]

According to the present invention, the alignment accuracy and reproducibility of the central axis of the burner and the target with the furnace are improved,
Furthermore, since the positional relationship during manufacturing is maintained, it is possible to stably manufacture silica glass having excellent characteristics, for example, good homogeneity with good reproducibility.

[Brief description of 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.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Hiroki Jimbo 3 2-3 Marunouchi, Chiyoda-ku, Tokyo Nikon Corporation (72) Inventor Hiroyuki Hiraiwa 3 2-3 Marunouchi, Chiyoda-ku, Tokyo Company Nikon

Claims (8)

[Claims] 1. A quartz glass manufacturing apparatus comprising a furnace, a target for forming an ingot installed inside the furnace, and a burner for synthesizing quartz glass installed with its tip facing the target. A quartz glass manufacturing apparatus having a positioning means for aligning the central axis of each burner with the furnace. 2. The quartz glass manufacturing apparatus according to claim 1, wherein an optical axis of a laser beam is used as the positioning means. 3. The quartz glass manufacturing apparatus according to claim 1, wherein a laser beam reflected by a mirror fixed to a burner is used as the positioning means. 4. The quartz glass manufacturing apparatus according to claim 1, wherein the alignment accuracy is ± 1 mm or less. 5. A method for producing a silica glass, in which a silicon compound gas, an oxygen gas, and a hydrogen gas are jetted from a burner and burned to deposit silica glass on a target to form an ingot, the central axes of the target and the burner respectively. And a furnace for aligning the quartz glass with each other. 6. The method for producing quartz glass according to claim 5, wherein the central axes of the burner and the target are aligned with the furnace by using the optical axes of the laser beams before the production. Method for producing quartz glass. 7. The method for producing quartz glass according to claim 5, wherein the position of the reflected light is measured by shining a laser beam on a mirror fixed to the burner during the production and adjusting the position of the burner accordingly. A method for producing quartz glass, characterized in that 8. The method for producing quartz glass according to claim 5, wherein the alignment accuracy is ± 1 mm or less.