Optimal Cooling System Design for Increasing the Crystal Growth Rate of Single-Crystal Silicon Ingots in the Czochralski Process Using the Crystal Growth Simulation

Hye Jun Jeon,Jae Hak Jung,Ganesh Koyyada,Salh Alhammadi,Hyeonwook Park

doi:10.3390/pr8091077

Abstract

Here, we report a successfully modified Czochralski process system by introducing the cooling system and subsequent examination of the results using crystal growth simulation analysis. Two types of cooling system models have been designed, i.e., long type and double type cooling design (LTCD and DTCD) and their production quality of monocrystalline silicon ingot was compared with that of the basic type cooling design (BTCD) system. The designed cooling system improved the uniformity of the temperature gradient in the crystal and resulted in the significant decrease of the thermal stress. Moreover, the silicon monocrystalline ingot growth rate has been enhanced to 18% by using BTCD system. The detailed simulation results have been discussed in the manuscript. The present research demonstrates that the proposed cooling system would stand as a promising technique to be applied in CZ-Si crystal growth with a large size/high pulling rate.

Highlights

Most single crystal silicon ingots are grown using the Czochralski process
The internal thermal stress of the crystal was improved by approximately 12% because longer residence time from the cooling zone during crystal growth and deeper crystal would result in lower internal temperature gradient of the crystal
The crystal growth rate of basic type cooling design (BTCD) and long type cooling design (LTCD) does not have a large margin of error, a difference of about 0.2 mm/min between the double type cooling design (DTCD) and the range of velocities could be confirmed through this experiment

Summary

Introduction

Most single crystal silicon ingots are grown using the Czochralski process. In this process, monocrystalline silicon is manufactured by contacting a silicon seed crystal from molten silicon and pulling it out slowly using a pulling system with crucible rotation [1]. It is necessary to reach a high crystal growth rate, but it is difficult to maintain the quality of the silicon crystal at a high crystal growth rate from a predetermined process. The twisting phenomenon of the crystal has limited attempts to achieve a high crystal growth rate in a given hot zone. The crystal defect area V/G (crystal growth rate (V)/temperature gradient (G) of the silicon melt–crystal interface region) must be considered [6,7]

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