Silicon Carbide Annealing Resistivity Control
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Solution Overview
Problem
Existing methods for fabricating silicon carbide materials with high resistivity often result in quality deterioration or cracking of the crystal or wafer, particularly when annealing temperatures exceed 2000°C.
Innovation Solution
A method involving a first annealing process with a heating rate of 10° C./min to 30° C./min and an annealing temperature of 2000°C or less, followed by optional polishing and a second annealing process, to achieve an average resistivity greater than 1010 Ω·cm without compromising the quality or integrity of the silicon carbide material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rapid annealing at high temperature (2000°C to 2400°C) is performed to improve resistivity, then the electrical characteristics of high-resistivity are achieved, but the quality of the crystal or wafer deteriorates or cracking occurs
Solution Approach 1:
The patent applies parameter changes by precisely controlling the annealing temperature range (1700°C to 2000°C) and heating rate (10°C/min to 30°C/min) to achieve the desired resistivity improvement while avoiding the harmful effects of excessive temperature. This controlled parameter adjustment resolves the contradiction between achieving high resistivity and maintaining crystal quality.
Solution Approach 2:
The patent employs dynamic control of the heating process by specifying a controlled heating rate rather than immediate high-temperature exposure. The gradual heating approach allows the crystal structure to adapt to temperature changes, preventing thermal shock and cracking while still achieving the necessary thermal treatment for improved resistivity.
2Reliability
If annealing temperature is increased above 2000°C to achieve higher resistivity, then the resistivity improves, but cracking and quality deterioration occur
Solution Approach 1:
The patent establishes an optimized temperature parameter range of 1700°C to 2000°C, which is lower than conventional approaches. This parameter change achieves the desired resistivity improvement (greater than 1010 Ω·cm) while eliminating the harmful cracking and quality deterioration that occur at temperatures above 2000°C.
Solution Approach 2:
The patent converts the potential harm of high-temperature treatment into a benefit by using a controlled, moderate temperature range that provides sufficient thermal energy to improve resistivity through point defect formation, while avoiding the excessive thermal energy that causes cracking. The controlled heating rate further transforms the potential harm of thermal stress into a beneficial gradual annealing process.
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
The method effectively increases the resistivity of silicon carbide materials while preventing quality deterioration or cracking, by carefully controlling the annealing temperature and heating rate within specific ranges.
Implementation Method 1
a first annealing process is performed on a wafer or on a crystal. Conditions of the first annealing process include: a heating rate of 10° C./min to 30° C./min, an annealing temperature of 2000° C. or less
Data Source
AI summary
A method of fabricating a silicon carbide material is provided. The method includes the following steps. A first annealing process is performed on a wafer or on an ingot that forms the wafer after wafer slicing. The conditions of the first annealing process include: a heating rate of 10° C./minute to 30° C./minute, an annealing temperature of 2000° C. or less, and a constant temperature annealing time of 2 minutes or more and 4 hours or less for performing the first annealing process. After performing the first annealing process, an average resistivity of the wafer or the ingot is greater than 1010 Ω·cm.