Silicon Crystal Gas Bubble Removal via Pressure and Temperature Shock
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Solution Overview
Problem
The challenge in manufacturing high-purity silicon single crystals is the incorporation of gas bubbles from the silica glass crucible, leading to void defects during the Czochralski process, which are difficult to detect non-destructively and significantly reduce semiconductor device yield.
Innovation Solution
Rapidly changing the chamber's internal pressure and temperature to remove gas bubbles from the crucible before starting the silicon single crystal pulling process, with preferred pressure and temperature change ratios to ensure effective bubble removal and prevent void defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the weight of silicon charged into the crucible is increased to produce large-scale silicon ingots, then productivity is improved, but gas bubbles become difficult to remove and void defects are generated in the crystal
Solution Approach 1:
The patent applies preliminary action by removing gas bubbles from the silicon melt before the crystal pulling process begins. The method involves charging the crucible with polysilicon, heating to melt, and removing gas bubbles while the crucible is stationary or rotating slowly, before initiating the crystal growth process. This ensures the melt is free of gas bubbles that would otherwise be incorporated into the crystal during pulling.
Solution Approach 2:
The patent employs dynamics by changing the rotation speed of the crucible during different stages of the process. The crucible rotation speed is adjusted dynamically: initially rotated at a first speed during melting and gas bubble removal, then changed to a second speed during crystal pulling. This dynamic adjustment optimizes both gas bubble removal efficiency and crystal growth quality.
2Object-generated harmful factors
If furnace pressure is adjusted to remove gas bubbles, then gas bubble removal is improved, but the process becomes more complex and gas bubbles cannot be sufficiently removed
Solution Approach 1:
The patent applies mechanical vibration by causing the crucible to vibrate during the gas bubble removal stage. The vibration helps detach gas bubbles from the crucible inner wall and promotes their rise to the surface for removal. This mechanical agitation method is more effective than simple pressure adjustment and avoids the complexity of precise pressure control while successfully removing gas bubbles.
3Object-generated harmful factors
If vibration is applied to the crucible to remove gas bubbles, then gas bubble removal is improved, but the process complexity increases
Solution Approach 1:
The patent merges the vibration function with the existing crucible rotation mechanism. The crucible is equipped with both rotation and vibration capabilities, and these functions are combined during the gas bubble removal stage. This integration avoids adding separate complex vibration mechanisms while effectively removing gas bubbles through the combined rotational and vibrational motion.
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 method effectively prevents gas bubbles from being incorporated into the silicon single crystal, resulting in high-quality silicon crystals with significantly reduced void defects and improved semiconductor device yield.
Implementation Method 1
polysilicon is charged into a silica glass crucible, heated and melted
Implementation Method 2
removing gas bubbles from a silicon melt within the silica glass crucible by rapidly changing at least one of a chamber internal pressure and temperature
Data Source
AI summary
A method for manufacturing a silicon single crystal is provided including producing a silicon melt in a chamber by melting a silicon raw material loaded into a silica glass crucible under a reduced pressure and high temperature, removing gas bubbles from within the silicon melt by rapidly changing at least the pressure or temperature within the chamber, and pulling up the silicon single crystal from the silicon melt after the gas bubbles are removed. When the pressure is rapidly changed, the pressure within the chamber is rapidly changed at a predetermined change ratio. In addition, when the temperature is rapidly changed, the temperature within the chamber is rapidly changed at a predetermined change ratio. In this way, Ar gas attached to an inner surface of the crucible and h is the cause of the generation of SiO gas is removed.