Processing process for preparing single crystal silicon through Czochralski method

Abstract

The invention discloses a processing technology for preparing single crystal silicon by the Czochralski method, which comprises the following steps: necking growth: when the temperature of the silicon melt is stabilized to a certain temperature, the seed crystal is immersed in the silicon melt, and the seed crystal is Increase the pulling speed at a certain rate to reduce the diameter of the seed crystal to 3-7mm; shoulder growth: after the necking growth is completed, reduce the crucible temperature and pulling speed, adjust the crucible rotation speed and crystal rotation speed, and increase the crystal to the required diameter; equal-diameter growth: after the shoulder growth is completed, adjust the crucible temperature, pulling speed, crucible rotation speed and crystal rotation speed, so that the diameter of the ingot is maintained between plus and minus 2mm; the present invention adds pure boron to the single crystal silicon raw material, The mass ratio of pure boron to monocrystalline silicon raw materials is 5%-15%, so that the resistivity of monocrystalline silicon can reach 300Ω / CM, and the radial uniformity of resistivity is within 3%; reduce the oxygen content in silicon melt It effectively inhibits the entry of oxygen from the silicon melt into the silicon crystal, improves work efficiency, and reduces the oxygen content of the silicon crystal.

Description

technical field [0001] The invention belongs to the technical field of monocrystalline silicon preparation, and in particular relates to a processing technology for preparing monocrystalline silicon by a Czochralski method. Background technique [0002] According to different crystal growth methods, single crystal silicon can be divided into Czochralski method (CZ), zone melting method (FZ) and epitaxy method. Single crystal silicon rods are grown by Czochralski method and zone melting method, and single crystal silicon thin films are grown by epitaxial method. Monocrystalline silicon grown by the Czochralski method is mainly used in semiconductor integrated circuits, diodes, epitaxial wafer substrates, solar cells, etc., and the Czochralski method accounts for more than 80% of the market. [0003] The resistivity of single crystal silicon produced by domestic Czochralski silicon single crystal manufacturers is generally within 20Ω / CM (P type) and 10Ω / CM (N type). Due to t...

AI Technical Summary

Problems solved by technology

Due to the low doping amount of Czochralski high-resistance silicon single crystal, the thermal field in the Czochralski single crystal furnace and the contamination of the quartz crucible, and the volatilization of phosphorus when pulling N-type single crystal silicon, in addition, the resistivity of the single crystal rod The processing process has a great influence on the resistivity test, which leads to difficulties in the stable production of Czochralski high-resistance silicon single crystals, and the actual resistivity deviation of the head of each single-crystal silicon rod is relatively large.

[0004] At the same time, if under the conditions of the existing method for preparing silicon single crystal by the Czochralski method, the feeding amount is increased (generally, the increased feeding amount is not more than 50kg on the basis of the conventional feeding amount), the melt height in the crucible will increase, and there are more crystal defects in the head of the equal-diameter part of the prepared silicon single crystal rod, such as swirl defects, oxidation-induced stacking faults, etc.

This is due to the high melt height in the quartz crucible and the strong heat convection of the melt (heat convection is usually proportional to the third power of the melt height), and strong heat convection will increase the oxygen transport capacity of the melt and cause The temperature stability of the long crystal interface (solid-liquid interface) deteriorates, which in turn leads to an increase in the oxygen content at the head of the equal-diameter part of the single crystal silicon rod and a decrease in the minority carrier lifetime

The part of the single crystal silicon rod whose minority carrier life does not meet the requirements, such as the head of the equal-diameter part, will be removed. Therefore, under the current process conditions, increasing the feeding amount will not only reduce the cost, but will cause great waste