A single crystal furnace for preparing silicon single crystal by Czochralski method

Abstract

The invention relates to the technical field of silicon wafer preparation, and discloses a single crystal furnace for preparing silicon single crystal by the Czochralski method, which comprises a furnace body, a furnace opening on the top of the furnace body, an exhaust port on the bottom of the furnace body, and an inner chamber of the furnace. A guide tube is installed on the top of the furnace body, and a graphite crucible is fixedly connected to the top of the exhaust port through a support shaft inside the furnace body. A quartz crucible is fixedly installed inside the graphite crucible, and the inner wall of the furnace is located between the furnace mouth and the guide tube. The lifting control ring is fixedly installed, and the top of the guide tube is evenly fixed in a ring shape near the outside with a slide bar. The corrugated pipe is evenly and fixedly connected in a ring shape, and the top surface of the guide tube is uniformly and fixedly installed with an air pressure regulating device in a ring shape. The bottom of the bellows is movably socketed with a fixed sliding shaft. High quality isometric, safe and stable.

Description

technical field [0001] The invention relates to the technical field of silicon chip preparation, in particular to a single crystal furnace for preparing silicon single crystal by Czochralski method. Background technique [0002] Monocrystalline silicon is the basic raw material needed for silicon wafers. Monocrystalline silicon is prepared by the Czochralski method in a single crystal furnace, that is, the high temperature quartz crucible in the furnace is filled with molten silicon material, and the seed crystal is grown in it. Pull out a single crystal silicon column. Although this method of preparing single crystal silicon has been widely used, there are still some problems in the preparation of single crystal silicon: [0003] 1. When the equal-diameter process section is carried out, the single crystal silicon in the silicon solution is pulled up, causing the liquid level to drop. In order to ensure the distance between the liquid level and the guide tube, the crucible ...

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Problems solved by technology

[0003] 1. When the equal-diameter process section is carried out, the single crystal silicon in the silicon solution is pulled up, causing the liquid level to drop. In order to ensure the distance between the liquid level and the guide tube, the crucible is moved upward. When moving up, it will cause several defects: friction will occur between the heater and the graphite crucible, and the friction will damage the graphite, causing the distance between the heater and the graphite crucible to increase, which is not conducive to the heat transfer between the heater and the graphite crucible ; At the same time, moving upwards will cause the relative position between the heater and the crucible to change, causing the top of the crucible to be unable to be heated, but the support shaft at the bottom of the crucible is heated, which will not only cause uneven heating but also cause heat waste; During the upward movement of the crucible, since it contains silicon solution inside, it may shake, causing the silicon column with equal diameter to fail to meet the requirements of equal diameter; when the crucible moves upward and the elongation of the seed crystal will produce relative speed, resulting in The speed of the elongation is inconsistent with the speed when the crucible is not moving, so that the elongated silicon column is not of equal diameter

[0004] 2. The middle part of the guide tube passes the incoming argon gas, and flows through the place between the guide tube and the crucible, and finally discharges through the bottom of the single crystal furnace. When the elongation is carried out, the crucible will be moved, causing the guide tube and the crucible to At the same time, the gap between the guide tube and the crucible becomes smaller, and the introduction of argon gas cannot be precisely controlled, which will cause the air pressure on the inlet surface of the guide tube to be too large, thus It affects the air pressure in the entire furnace body, and the changing air pressure will cause disordered flow. On the one hand, it will cause the elongated silicon column to fail to meet the requirement of equal diameter under pressure, and it may also cause the silicon solution to slosh and cannot be elongated normally. Dangerous situations such as explosions caused by unstable air pressure

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