JP2878916B2 - Silica glass member for semiconductor heat treatment and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silica glass member for heat treatment of a semiconductor, and more particularly to a silica glass member for heat treatment of a semiconductor which does not deteriorate a wafer and a method for producing the same.

[0002]

2. Description of the Related Art Machines, devices, containers, and the like used in semiconductor manufacturing are required to have high heat resistance and high chemical purity. These components must not react with the wafer under any conditions or give any element, even traces, to the wafer. Conventionally, silica glass has been used as a material that meets such demands. Silica glass includes silica glass obtained by fusing and crystallizing crystalline quartz by an electric melting method (hereinafter referred to as electrofused silica glass), and silica glass obtained by fusing and crystallizing crystalline quartz by an oxyhydrogen flame method (hereinafter referred to as oxyhydrogen flame). Fused silica glass), and synthetic silica glass obtained by vitrifying silica produced by a sol-gel method or a soot method. However, the oxyhydrogen flame fused silica glass has a large amount of OH.
Since it contains a group, it has a disadvantage that it is crushed or deformed when used for a long time at a high temperature. Further, the synthetic silica glass has a disadvantage that the viscosity is lower than that of the silica glass obtained from the crystalline quartz powder, and bubbles are generated due to chlorine and hydrogen chloride mixed in during production, resulting in poor appearance. For this reason, conventionally, electrofused silica glass has been exclusively used as a jig for semiconductor industry, particularly as a jig material used in a process in which a heat treatment temperature is 1100 ° C. or higher.

However, a new evaluation method has recently been developed,
When the effect of silica glass on the wafer was examined by this evaluation method, it was found that the electrofused silica glass product caused the deterioration of the wafer despite its high purity.
To investigate the cause, a wafer was set on a boat made of electro-fused silica glass and a boat made of oxyhydrogen flame-fused silica glass and heat-treated in an electric furnace.
It was found that the lifetime of the wafer set on the electro-fused silica glass boat was larger than that of the wafer set on the oxyhydrogen flame fused silica glass boat. It is considered that the cause of the reduction in the lifetime is that metal impurity elements are incorporated into the oxide film of the wafer. Wafers, gases, silica glass and the like can be cited as sources of the metal impurities. However, the oxyhydrogen flame fused silica glass boat is considered to be present in the electrofused silica glass itself, since the problem of deterioration in lifetime is small. Can be But for some reason
Since the oxyhydrogen flame fused silica glass product is deformed by a high temperature process of 1100 ° C. or more and has a short service life, improvement of the electrofused silica glass member has been desired.

[0004]

The present inventors have been studying the effects of the above electrofused silica glass member on the wafer and the heat resistance of the glass.
It has been found that when the group content is 20 ppm or more, the decrease in the lifetime of the wafer is reduced. Also, heat resistance is O
When the H group content is 120 ppm or less, its viscosity [η]
Is within the range of 10 ^12.0 to 10 ^12.5 poise at 1250 ° C. even in a high temperature process of 1100 ° C. or more.
It turned out to be usable enough . The present invention has been completed based on these findings. That is,

SUMMARY OF THE INVENTION The present invention provides a silica glass part for semiconductor heat treatment mainly comprising an electro-fused silica glass with little wafer deterioration.
The purpose is to provide materials . Further, the present invention is mainly based on the electro-fused silica glass with less wafer deterioration
It is an object of the present invention to provide a novel method for producing a silica glass member for semiconductor heat treatment .

[0006]

SUMMARY OF THE INVENTION The present invention, which achieves the above object, comprises a silica glass obtained by electromelting crystalline quartz powder.
Silica glass obtained by melting with an oxyhydrogen flame: 1: 1 to 2
Semiconductor made of silica glass mixed at a ratio of 0: 1
The silica glass member for heat treatment, wherein the silica glass
The OH group content of the member is 20 ppm or more, 120 ppm or less
The viscosity [η] at 1250 ° C. is 10 ^12.0 to 1
0 Siri semiconductor heat treatment, which is a ^12.5
The present invention relates to a glass member and a method for manufacturing the member .

In the above description, "crystalline quartz powder" means glass raw material powder obtained by crushing and purifying natural crystalline silicon dioxide such as quartz. The particle size of this crystalline quartz powder is 10
When the particle size is 10 μm or less, the quartz powder is too fine and bubbles are generated. On the other hand, when the particle size is 1000 μm or more, purification is difficult, and impurities are likely to be mixed.

In the above electrofused silica glass member, O
H group content 20ppm or more, but less good 120 ppm, in particular 40ppm or more, less Mai good 120 ppm.
Exceed 120ppm not withstand the 1100 ° C. or more thermal treatment processes inferior heat resistance, and in less than 20ppm U
The effect of suppressing the deterioration of the wafer is small .

Further, the viscosity [η] at 1250 ° C.
Is preferably 10 ^12.0 or more and 10 ^12.5 or less, particularly preferably 10 ^12.1 poise or more and 10 ^12.5 poises or less. If the viscosity is less than 10 ^12.0 poise, the shape cannot be maintained during the heat treatment process at 1100 ° C. or more.
^It is difficult to produce silica glass exceeding ^12.5 poise.
You .

The silica glass member having the OH group content and the viscosity of the present invention is obtained by forming an electrofused silica glass material and an oxyhydrogen flame fused silica glass material into, for example, a rod shape, and holding the same on a lathe. While locally heating the rod-shaped body to at least the softening point with a burner or an electric heating furnace, the lathe is rotated to twist and join the two, and then the heating source is moved, and the joint is uniformly mixed. . The mixing ratio of the silica glass material constituting the member is preferably in the range of 1: 1 to 20: 1.

[0011]

EXAMPLE A silica glass rod obtained by electromelting crystalline quartz powder and a silica glass rod obtained by melting crystalline quartz powder in oxyhydrogen were prepared, and then these two types of silica glass rods were prepared. While holding it on a lathe and heating it to the softening point of the silica glass rod with a burner, the lathe is rotated to twist and bond both silica glass rods, and then the burner is moved to homogenously mix the bonded part and a diameter of 12 mm. Muku sticks were manufactured. A boat for wafer heat treatment was manufactured from the obtained sticks, the wafer was set, and oxidation treatment was performed at 1000 ° C. for 5 hours in a silica glass furnace core tube. Thereafter, the lifetime of the oxidized wafer was measured, and the ratio of the portion where the lifetime was 100 μsec or less of the standard value on the wafer surface was determined.

[0012] The obtained results were obtained by comparing the percentage of the silica glass material constituting the rod, the OH group content of the rod, and 12%.
Viscosity at 50 ° C. [η] (Beam Bending
Table 1 together with the method).

[0013]

[Table 1]

<Evaluation> As shown in Table 1, a boat formed of a silica glass member containing an OH group within the range specified in the present invention is 110
Even when used at 0 ° C., there is no deformation and there is little deterioration in the lifetime of the wafer. As described above, the silica glass member for heat treatment of a semiconductor according to the present invention has a low viscosity even at 1250 ° C. and is excellent as a member for heat treatment of a semiconductor.

On the other hand, a member having an OH group content outside the range specified in the present invention, for example, as shown in Comparative Example 1, 13
A member having an OH group content of 0 ppm has a viscosity [η] at 1250 ° C. of as low as ^1011.9 poise and 1100
The boat is deformed during the heat treatment at ℃, and needs to be replaced in half the time as compared with the boat of Example 2. As shown in Comparative Example 3, the silica glass member having an OH group content of 180 ppm has a viscosity [η] at 1250 ° C. of 10
^As low as ^11.8 poise, the boat formed of this silica glass member deformed in a short time as in Comparative Example 1, and was unsuitable as a semiconductor heat treatment member.

[0016]

According to the present invention, the silica glass part for semiconductor heat treatment of the present invention.
The material has high heat resistance and is treated with silicon
Induces degradation such as reducing the lifetime of the wafer
It is an excellent silica glass member for heat treatment that does not suffer from heat.
Moreover, the silica glass member for heat treatment is made of electro-fused silica.
Holds glass and oxyhydrogen flame fused silica glass on lathe
While heating to a temperature above the softening point of both silica glasses.
Rotating the board and twisting it while heating and homogenously mixing
It is a member that can be easily manufactured with
You.

Continuation of front page (58) Field surveyed (Int. Cl. ⁶ , DB name) C03C 3/04 C03B 20/00 C03C 4/00 H01L 21/324

Claims (2)

(57) [Claims] 1. A silica powder obtained by electromelting crystalline quartz powder.
Lath and silica glass obtained by melting with an oxyhydrogen flame:
Made of silica glass mixed in a ratio of 1-20: 1
In a silica glass member for semiconductor heat treatment, the silica
OH group content of glass member is more than 20ppm, 120p
pm or less and the viscosity [η] at 1250 ° C. is 10
Semiconductor characterized by being ^12.0 to ^12.5
Silica glass member for heat treatment. 2. A method in which silica glass obtained by electromelting crystalline quartz powder and silica glass obtained by melting with an oxyhydrogen flame are held on a lathe and heated to a temperature not lower than the softening point of both silica glasses. A method for producing a silica glass member for heat treatment of a semiconductor, characterized in that a lathe is rotated and twisted while being heated and bonded to be homogeneously mixed.