Monocrystalline Silicon Pulling with Controlled Decompression
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Solution Overview
Problem
Monocrystalline silicon produced using the Czochralski process with volatile dopants often experiences dislocations during pulling, necessitating re-melting and re-pulling, which affects production efficiency and quality.
Innovation Solution
A method involving a controlled decompression rate of the chamber from atmospheric pressure to 80 kPa at a rate of 0 to 4.2 kPa/min during the initial exhaust step in the Czochralski process to reduce the occurrence of dislocations by minimizing the evaporation and adherence of volatile dopants to the piping system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a volatile dopant is added to the silicon melt to reduce resistivity, then the electrical resistivity of monocrystalline silicon is lowered, but dislocations occur during pulling
Solution Approach 1:
The patent changes the decompression rate parameter from a conventional high rate to a controlled low rate (0 to 4.2 kPa/min), which fundamentally alters the evaporation behavior of volatile dopants during the vacuum exhaust process, thereby resolving the contradiction between achieving low resistivity and preventing dislocations
2Productivity
If rapid decompression is performed to reduce processing time, then productivity is improved, but dislocation occurrence increases due to rapid dopant evaporation
Solution Approach 1:
The patent applies preliminary action by carefully controlling the decompression rate during the initial vacuum exhaust phase before the pulling process begins. This preliminary control of the gas environment prevents dopant evaporation issues that would otherwise occur during pulling, thereby enabling both high productivity and high manufacturing precision
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces dislocation rates during monocrystalline silicon pulling, improving production efficiency and maintaining low electrical resistivity, as demonstrated by a comparative example showing a dislocation reduction from 100% to 38% when the decompression rate is limited to 4.2 kPa/min or lower.
Implementation Method 1
a decompression rate ES for exhaust of a gas out of the chamber before the pulling of the monocrystalline silicon is within a range below at least until a pressure inside the chamber decreases from an atmospheric pressure to 80 kPa
Data Source
AI summary
A method of manufacturing monocrystalline silicon is provided, the method including pulling monocrystalline silicon out of a silicon melt by a Czochralski process, the silicon melt being stored in a crucible housed in a chamber, the silicon melt being added with a volatile dopant, in which a decompression rate ES for exhaust of a gas out of the chamber before the pulling of the monocrystalline silicon is within a range below at least until a pressure inside the chamber decreases from an atmospheric pressure to 80 kPa, 0 kPa/min<ES≤4.2 kPa/min.