MCZ Silicon Crystal Oxygen Control via Magnetic Field
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Solution Overview
Problem
Existing methods struggle to consistently achieve an oxygen concentration of 1.6×10^18 atoms/cm^3 or more in silicon single crystals over their entire length, particularly during the second half of crystal growth, due to decreased melt volume and contact area with the crucible, which is crucial for producing phosphorus-doped silicon wafers with enhanced radiation resistance.
Innovation Solution
A Magnetic field applied Czochralski (MCZ) method is employed, where a horizontal magnetic field with a strength of 2,000 gauss or more is applied to the silicon melt, along with a phosphorus dopant concentration of 2×10^16 atoms/cm^3, to control the oxygen concentration and achieve a uniform high oxygen level throughout the crystal, using a single-crystal pulling apparatus with specific furnace pressure adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional CZ method is used to produce silicon single crystal, then the crystal can be grown with standard oxygen concentration, but the oxygen concentration cannot be maintained at 1.6×10^18 atoms/cm³ or more over the entire length of the crystal, especially during the second half of growth
Solution Approach 1:
The patent applies a horizontal magnetic field (parameter change) during the crystal growth process to control and maintain the oxygen concentration at 1.6×10^18 atoms/cm³ or more throughout the entire crystal length, resolving the contradiction between achieving high oxygen concentration uniformity and maintaining efficient productivity
Solution Approach 2:
The patent replaces conventional mechanical control methods with magnetic field application to control oxygen concentration distribution, enabling precise control of oxygen incorporation during crystal growth without compromising growth efficiency
2Manufacturing precision
If the melt volume is decreased during the second half of crystal growth, then the crystal can be pulled with controlled composition, but the contact area between the wall of the quartz crucible and the melt is decreased, making it difficult to maintain high oxygen concentration
Solution Approach 1:
The horizontal magnetic field acts as an intermediary that mediates between the decreasing melt volume and the requirement for high oxygen concentration, enabling maintained control of oxygen incorporation despite reduced melt quantity during the second half of growth
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 successfully produces silicon single crystals with an oxygen concentration of 1.6×10^18 atoms/cm^3 or more over the entire length, enabling the production of high-quality wafers with improved electrical characteristics suitable for radiation-resistant semiconductor devices.
Implementation Method 1
a horizontal magnetic field is applied to the silicon melt with a central magnetic field strength of 2,000 gauss or more such that the phosphorus-doped silicon single crystal to be produced has an oxygen concentration of 1.6×10^18 atoms/cm³ (ASTM'79) or more
Data Source
AI summary
A method of producing a phosphorus-doped silicon single crystal, including pulling the phosphorus-doped silicon single crystal from a silicon melt doped with phosphorus by Magnetic field applied Czochralski (MCZ) method, wherein the phosphorus is doped such that a phosphorus concentration of the phosphorus-doped silicon single crystal is 2×1016 atoms/cm3 or more, and a horizontal magnetic field is applied to the silicon melt with a central magnetic field strength of 2,000 gauss or more such that the phosphorus-doped silicon single crystal to be produced has an oxygen concentration of 1.6×1018 atoms/cm3 (ASTM'79) or more. A method of producing a silicon single crystal that is heavily doped with phosphorus and has an oxygen concentration of 1.6×1018 atoms/cm3 (ASTM'79) or more.