Silicon Carbide Wafer Relaxation Moduli Control
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Solution Overview
Problem
Silicon carbide ingots and wafers often suffer from deformation, defects, and breakage due to stress factors during transport, machining, or processing, and maintaining uniform physical properties is challenging due to variations in crucible characteristics and process conditions.
Innovation Solution
A method involving controlled growth of silicon carbide ingots using physical vapor transport, where a raw material and seed crystal face each other in a reactor with controlled temperature, pressure, and inert gas flow, resulting in ingots with improved elastic modulus and creep properties, and subsequent wafer manufacturing with specific relaxation moduli, creep compliance, and stiffness to minimize deformation and defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If physical vapor transport is used to grow silicon carbide ingots, then fast growth rate is achieved, but uniform physical properties of the final ingot cannot be ensured
Solution Approach 1:
The patent applies parameter changes by precisely controlling temperature distribution, pressure conditions, and inert gas flow rates during the physical vapor transport process. By optimizing these parameters, the method achieves both fast growth rates and uniform physical properties in the silicon carbide ingots, resolving the contradiction between productivity and manufacturing precision.
Solution Approach 2:
The patent implements feedback control through continuous monitoring and adjustment of process conditions during ingot growth. By measuring temperature distribution, gas flow patterns, and growth rate, the system makes real-time adjustments to maintain uniform physical properties while sustaining high productivity.
2Ease of manufacture
If silicon carbide wafers are subjected to stress factors during transport and machining, then processing is enabled, but deformation and breakage occur
Solution Approach 1:
The patent applies preliminary action by optimizing the crystal growth process to pre-establish uniform physical properties and reduce internal stresses in the ingot before machining. This preliminary optimization of material structure enables subsequent processing while minimizing deformation and breakage, resolving the contradiction between ease of manufacture and strength.
3Force
If relaxation modulus difference between loaded conditions is large, then wafer stiffness varies under different loads, but this leads to increased deformation under stress
Solution Approach 1:
The patent applies parameter changes by controlling the physical and chemical conditions during crystal growth to achieve uniform density and structural consistency. This results in wafers with consistent relaxation moduli across different loading conditions, maintaining stability of mechanical properties while preserving load-bearing capacity.
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 produces silicon carbide ingots and wafers with enhanced elastic modulus and creep properties, reducing deformation and defect occurrence, and ensuring high crystal quality, which is crucial for subsequent device fabrication.
Implementation Method 1
the crucible is heated by induction to sublimate the raw material, and as a result, single-crystal silicon carbide is grown on the seed crystal
Implementation Method 2
cooling the reactor and recovering the silicon carbide ingot
Data Source
AI summary
A wafer having relaxation moduli different by 450 GPa or less, as determined by dynamic mechanical analysis, when loaded to 1 N and 18 N with a loading rate of 0.1 N/min at a temperature of 25° C.