Silicon Monocrystal Pulling With Ar Flow for Dislocation Prevention
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Solution Overview
Problem
The incorporation of a solid dopant into a solid-liquid interface before dissolution causes dislocation in silicon single crystals during counter doping, particularly in the production of IGBTs where reduced Ar gas flow leads to high oxygen concentration.
Innovation Solution
Adjusting the Ar gas flow rate and pressure in the pulling-up furnace during the addition of a secondary dopant, increasing the flow rate and decreasing the pressure to prevent non-melted dopant incorporation at the solid-liquid interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a solid dopant is added to a silicon melt in a quartz crucible during counter doping, then the resistivity uniformity is improved, but dislocation occurs in the silicon single crystal
Solution Approach 1:
The patent applies preliminary action by pre-melting the solid dopant into the silicon melt before the dopant can reach the solid-liquid interface. The dopant is added in a form that is already or quickly becomes liquid, ensuring complete dissolution in the melt before incorporation into the crystal, thereby preventing dislocation while maintaining resistivity uniformity
Solution Approach 2:
The patent changes the physical state parameter of the dopant from solid to liquid by controlling the melting temperature and adding the dopant at appropriate temperatures. This parameter change ensures the dopant is fully dissolved in the melt before reaching the solid-liquid interface, preventing dislocation while achieving uniform resistivity distribution
2Manufacturing precision
If the Ar gas flow rate is reduced in the pulling-up furnace, then the oxygen concentration in the single crystal is lowered, but the dopant dissolution is incomplete causing dislocation
Solution Approach 1:
The patent applies preliminary action by pre-melting the dopant and ensuring complete dissolution in the melt before the dopant reaches the solid-liquid interface. This preliminary dissolution action occurs regardless of the Ar gas flow rate, ensuring that even at reduced flow rates for oxygen control, the dopant is fully dissolved and不会 cause dislocation
Solution Approach 2:
The patent uses the silicon melt as an intermediary medium that facilitates complete dopant dissolution before the dopant reaches the solid-liquid interface. The melt acts as a buffer that ensures thorough mixing and dissolution, allowing reduced Ar gas flow rates to be used for oxygen control without compromising crystal quality
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
Prevents dislocation of silicon single crystals by ensuring the secondary dopant is fully dissolved in the melt, maintaining uniform resistivity and reducing oxygen concentration.
Implementation Method 1
the flow rate of Ar gas supplied to a pulling-up furnace during a first period in which the secondary dopant is not added is set as a first flow rate, and the flow rate of Ar gas supplied to the pulling-up furnace during a second period that includes a period in which the secondary dopant is added is set as a second flow rate that is greater than the first flow rate
Data Source
AI summary
Provided is a manufacturing method of a silicon single crystal according to the present invention includes a melting process for generating a silicon melt containing a primary dopant, and a crystal pulling-up process that pulls up a silicon single crystal from the silicon melt. The crystal pulling-up process includes at least one additional doping process for adding a dopant raw material containing a secondary dopant into the silicon melt. A flow rate of Ar gas during a first period in which the secondary dopant is not added is set as a first flow rate, and the flow rate of Ar gas during a second period that includes a period in which the secondary dopant is added is set as a second flow rate that is greater than the first flow rate.