JPH02250326A - Semiconductor manufacturing apparatus - Google Patents

Abstract

PURPOSE:To prevent a life of a core tube from being lowered by a loss at a tip part of a hydrogen-gas supply tube and to enhance a yield of a semiconductor device by a method wherein the tip part of the hydrogen-gas supply tube is made of a ceramic whose heat resistance is high and whose purity is high. CONSTITUTION:A tip part 3 of a hydrogen-gas supply tube 1 for a semiconductor manufacturing apparatus provided with a core tube 4 used for pyrogenic oxidation is made of a ceramic whose heat resistance is high and whose purity is high. It is preferable that a heat-resistant temperature of this ceramic is 1500 deg.C and that its purity is 99% or higher. Thereby, it is possible to prevent a life of the core tube from being lowered by a loss at the tip part of the hydrogen-gas supply tube at a high temperature; it is possible to reduce defective wafers caused by impurity particles and to enhance a yield of semiconductor devices to be oxidized.

Description

[Detailed Description of the Invention] Field of Industrial Application] The present invention extends the life of a combustion oxidation furnace core tube in the oxidation process of silicon wafers in a semiconductor manufacturing process, and also reduces the amount of gas generated from this combustion oxidation furnace core tube. The present invention relates to semiconductor manufacturing equipment equipped with a furnace core tube that suppresses dust and improves the yield of semiconductor devices.

[Prior Art] In conventional semiconductor manufacturing equipment equipped with a furnace core tube for combustion oxidation, the material of the furnace core tube is mainly quartz, and when used at particularly high temperatures, it may be manufactured from SiC. be.

In the conventional pyrogenic oxidation (oxygen-hydrogen combustion oxidation) method, hydrogen and oxygen gas are supplied into the furnace core tube from supply tubes, respectively, and hydrogen gas is released at the tip of the hydrogen gas supply tube that protrudes inside the furnace core tube. The silicon wafer placed inside the furnace core tube is oxidized by burning it. Conventionally, the furnace core tube and gas supply tube are all made of quartz.

However, with this structure and oxidation method, the area around the tip of the hydrogen gas supply pipe is filled with high-temperature steam, and the portion of the hydrogen supply pipe that protrudes into the interior of the furnace core tube is exposed to a reducing atmosphere of hydrogen. Particularly at the tip, the temperature becomes particularly high due to heat generated by combustion of hydrogen/oxygen.

Under such an environment, the tip of the quartz gas supply pipe will devitrify within a short period of time, and at the same time as the quartz glass devitrifies, S; The particles get mixed into the gas inside the furnace core tube and adhere to the silicon wafer, reducing the yield of devices when oxidizing the silicon wafer, and the gas supply tube itself gradually disappears, making it unusable. The inside of the tip of the gas supply pipe is made of Si.
O2 is reduced, causing evaporation and precipitation of SiO, which also causes generation of impurity particles and loss of gas supply pipes.

[Problems to be Solved by the Invention] The purpose of the present invention is to improve the above-mentioned drawbacks of the prior art, to improve the yield of semiconductor devices without generating impurity particles or losing hydrogen gas supply pipes, and to have a long life. Our mission is to provide furnace core tubes.

[Means for achieving the object] According to the present invention, the object of the present invention is a semiconductor manufacturing apparatus equipped with a furnace core tube used for pyrogenic oxidation.
The furnace core tube includes a hydrogen gas supply pipe attached to the furnace core tube such that a tip thereof projects into the interior of the furnace core tube;
an oxygen gas supply pipe attached to the furnace core tube so as to communicate with the inside of the furnace core tube, and the tip of the hydrogen gas supply tube is made of highly heat-resistant and high-purity ceramics. achieved by the device.

[Because the tip of the hydrogen gas supply tube is made of highly heat-resistant and high-purity ceramics, it can prevent the life of the furnace core tube from decreasing due to loss of the tip of the hydrogen gas supply tube under high temperatures. In addition, the yield of semiconductor devices to be oxidized can be improved by reducing the number of defective silicon wafers due to the generation of impurity particles.

[Specific Examples] The present invention will be explained based on specific examples. In Figure 1,
1 is a hydrogen gas supply pipe, 2 is its tip, 3 is a tip member attached to the tip 2, 4 is a furnace core tube, 5 is an oxygen gas supply pipe, 6 is a silicon wafer to be oxidized, and 7 is a silicon wafer In the furnace core tube 4, a hydrogen gas supply tube 1 and an oxygen gas supply tube 5 respectively pass through the closed end of the furnace core tube 4, and the tip end 2 is inserted into the furnace core tube 4. It is attached to the furnace core tube 4 so as to protrude.

The tip member 3 that is not attached to the tip 2 of the hydrogen gas supply pipe 1, which is exposed to water vapor and hydrogen gas at high temperatures, is made of highly heat-resistant, high-purity ceramics, such as Si 3N 4 sintered body, SiC.
It is made of a sintered body, At 203 sintered body, etc. The tip member 3 is detachably attached to the tip portion 2.

The tip member 3 may have the tip portion 2 coated with the above-mentioned highly heat-resistant, high-purity ceramics, or may be made integrally with the hydrogen gas supply pipe using the above-mentioned highly heat-resistant, high-purity ceramics. good.

From the viewpoint of cost and workability, it is practical to manufacture the tip member 3 separately and attach it to the tip portion 2.

The tip member 3 is made of high-11-it thermal and high-purity ceramics, and the materials include, for example, Si 3N 4 sintered body, S
iC sintered bodies (including Si-impregnated products), ^1. 03 Sintered body or single crystal AI 203. There is Sialon etc. T:2
03, Too (a), BN (cubic), 2
R02 etc. can also be used, but it is a little less practical than the previous champion due to price, workability, etc. Regarding the degree of high heat resistance of the ceramic of this specific example, the heat resistance temperature is 1.5 GO" C5 of the same high purity. In terms of purity, it is preferable that the purity is 99% or more.The materials other than these ceramics, such as the entire gas supply pipe or the entire furnace core tube, must be of high purity, high heat resistance, and do not devitrify at high temperatures and reducing atmospheres, or have a large amount of devitrification. The silicon wafer may be made of a material that does not evaporate and does not adversely affect the characteristics of the silicon wafer.

Although mullite and other so-called refractory brick materials are heat resistant and corrosion resistant, they have a strong tendency to become a source of alkali metal impurities that adversely affect the properties of silicon wafers, and are therefore not suitable.

In an apparatus equipped with a furnace core tube made of the materials described above, a silicon wafer to be oxidized is set in advance inside the furnace core tube 4. Next, oxygen and hydrogen are supplied to the inside of the furnace core tube from the gas supply pipes 1 and 5, and the tip 2 of the hydrogen gas supply pipe 1 is combusted at high temperature (i, ooo °C to 1,300 °C). Silicon wafers can be oxidized to produce high quality silicon wafers.

Pyrogenic oxidation was performed three times in the conventional furnace core tube structure and the furnace core tube according to the present invention under conditions of 1,100°C for 3 hours, and the oxidized silicon wafers were tested using a wafer surface foreign matter inspection device. The results of counting the number of impurity particles on the surface of a silicon wafer are shown in FIGS. 2 to 7.

In the conventional furnace core tube device, one made of quartz is used, and in the device equipped with the furnace core tube according to the present invention, the tip member 3 that is attached to the hydrogen gas supply tube 1 is made of a high-purity StC sintered body. I used something.

In the case of the conventional f-core tube device, in FIG. 2, the number of small impurity particles (size: 0.3 to 0.5 μm) (hereinafter referred to as S) is 14. The number of medium impurity particles (size: 0.5 to 2 μl) (hereinafter referred to as M) is 4. Large impurity particles (size 2μ
m or more) (hereinafter referred to as less) is 5. 23 in total, S is 6 in Figure 3. M is 3°L is 8. 17 in total, S is 1 in Figure 4
29M is 1°L is 5. In contrast, in the case of the furnace core tube according to the present invention, S is 3. M is 1. L
is 0. Total 4, S is 6 in Figure 6. M is 0. L is 0° total 6
, in Figure 7, S is 6. M is 1. L is 1. There were 8 in total.

In this way, when using the furnace core tube according to the present invention,
It is clear that the number of particles adhering to the silicon wafer is reduced. Note that since the difference in thermal expansion coefficient between the tip member 3 and the tip portion 2 is small, the problem that the tip member 3 or the tip portion 2 breaks under high temperature does not occur.

[Effects of the Invention] In the device according to the present invention, since the tip of the hydrogen gas supply tube is made of highly heat-resistant and high-purity ceramics, impurity particles are not likely to be generated at the tip of the hydrogen gas supply tube under high temperatures. The yield of semiconductor devices to be oxidized can be improved by reducing the number of defective silicon wafers caused by the oxidation process.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a specific example of a furnace core tube according to the present invention, FIGS. 2 to 4 are diagrams showing the number of impurity particles on the surface of a silicon wafer after oxidation by a conventional furnace core tube, and 7 to 7 are diagrams showing the number of impurity particles on the surface of a silicon wafer after oxidation using a specific example of the furnace core tube according to the present invention. DESCRIPTION OF SYMBOLS 1...Hydrogen gas supply pipe, 2...Tip part, 3...Tip member, 4...Furnace core tube, 5
...Oxygen gas supply pipe, 6...Silicon wafer. Toshiba Ceramics Corporation

Claims (1)

[Claims] A semiconductor manufacturing apparatus equipped with a furnace core tube used for pyrogenic oxidation, the furnace core tube having a hydrogen gas supply attached to the furnace core tube such that a tip portion thereof protrudes into the interior of the furnace core tube. and an oxygen gas supply pipe attached to the furnace core tube so as to communicate with the inside of the furnace core tube,
The device in which the tip of the hydrogen gas supply pipe is made of highly heat-resistant and high-purity ceramics.