Silicon Single Crystal Pulling Oxygen Concentration Control
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Solution Overview
Problem
Silicon single crystals pulled under conditions corresponding to the I-rich region exhibit slip from their shoulder portion to the top part of their straight cylinder portion, due to interstitial-type point defects, which existing methods fail to prevent effectively.
Innovation Solution
The silicon single crystal is pulled with an oxygen concentration equal to or higher than 9.0×10^17 atoms/cm^3 and thermal stress values below a certain threshold in the region from the shoulder portion to the top part of the straight cylinder portion, controlled by adjusting the quartz crucible rotations and applying a magnetic field, to prevent slip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the silicon single crystal is pulled under conditions corresponding to the I-rich region to reduce void defects, then the concentration of interstitial-type point defects increases, but slip occurs from the shoulder portion to the top part of the straight cylinder portion
Solution Approach 1:
The patent applies parameter changes by controlling the oxygen concentration parameter to be equal to or higher than 9.0×10^17 atoms/cm³ during crystal pulling under I-rich region conditions. This parameter adjustment prevents slip while maintaining the benefits of reduced void defects, as oxygen acts to suppress dislocation movement and slip in the crystal structure.
Solution Approach 2:
The patent uses oxygen as an intermediary element to resolve the contradiction between reducing void defects and preventing slip. By introducing oxygen into the crystal structure at controlled concentrations, it mediates the interaction between interstitial-type point defects and the crystal lattice, preventing slip without eliminating the beneficial low-void-defect conditions of the I-rich region.
2Strength
If the oxygen concentration is increased to prevent slip, then the crystal strength increases, but the complexity of controlling growth conditions increases
Solution Approach 1:
The patent simplifies the control complexity by establishing a specific threshold value for oxygen concentration (equal to or higher than 9.0×10^17 atoms/cm³). This clear parameter specification provides a straightforward control target for manufacturers, avoiding the need for complex multi-parameter optimization while achieving the desired crystal strength and slip prevention.
3Reliability
If the thermal stress is reduced to prevent slip, then the occurrence of dislocation-induced slip is suppressed, but the productivity may be affected due to extended growth time
Solution Approach 1:
The patent resolves the productivity concern by controlling the thermal stress parameter to remain below a specific threshold during the crystal pulling process. This allows for optimized growth conditions that prevent slip without requiring excessively long growth times, as the controlled thermal stress environment enables faster pulling rates while maintaining crystal integrity.
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 effectively prevents slip by maintaining high oxygen concentrations and low thermal stress, enhancing crystal strength and preventing dislocation-induced slip in the silicon single crystal.
Implementation Method 1
the silicon single crystal is pulled under conditions such that an oxygen concentration in a region of the silicon single crystal from its shoulder portion to a top part of its straight cylinder portion is equal to or higher than a predetermined concentration at which no slip starting from the interstitial-type point defects occurs
Implementation Method 2
controlled by adjusting the quartz crucible rotations
Implementation Method 3
applying a magnetic field
Implementation Method 4
thermal stress values below a certain threshold in the region from the shoulder portion to the top part of the straight cylinder portion
Data Source
AI summary
A method for producing a silicon wafer in which occurrence of slip starting from interstitial-type point defects is prevented in a part from the shoulder to the top of the straight cylinder portion of a silicon single crystal when the silicon single crystal is grown by pulling method under growth conditions entering an I-rich region. In order to prevent occurrence of slip in the range from the shoulder (10A) to the top of the straight cylinder portion (10B), the silicon single crystal (10) is pulled under conditions that the oxygen concentration Oi from the shoulder (10A) to the top of the straight cylinder portion (10B) of the silicon single crystal (10) is not lower than a predetermined concentration for preventing slip starting from interstitial-type point defects, more specifically not lower than 9.0×1017 atoms/cm3.