SiC Substrate Growth and Peeling for Large-Diameter Low-Defect Wafers
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Solution Overview
Problem
Current methods for producing SiC substrates face challenges in achieving large-diameter substrates with high quality due to limitations in growth rate, defect density, and productivity, particularly with the solution method, high temperature CVD method, and sublimation method.
Innovation Solution
A method involving an etching step to remove the subsurface damaged layer, a crystal growth step using a temperature gradient to grow the SiC substrate layer, and a peeling step to produce a high-quality SiC substrate without the need for CMP polishing, allowing for the production of large-diameter substrates with reduced defect density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If CMP polishing is performed on the growth surface of the seed crystal substrate to produce SiC substrates one by one, then substrate quality is improved, but production cost increases due to repeated polishing operations
Solution Approach 1:
The patent combines multiple processing steps (etching, crystal growth, and peeling) into a single integrated apparatus system, eliminating the need for separate CMP polishing operations. The SiC base substrate undergoes etching and crystal growth in one continuous process, reducing the number of discrete manufacturing steps and associated costs.
Solution Approach 2:
The invention extracts and eliminates the CMP polishing step from the traditional manufacturing process. By using etching to remove the subsurface damaged layer followed by in-situ crystal growth, the patent removes the need for repeated CMP polishing that was required in conventional methods.
2Productivity
If the sublimation method is used to grow SiC substrates, then production speed is improved, but defect density increases making large-diameter substrates difficult to produce
Solution Approach 1:
The patent changes the fundamental growth parameters by using a temperature gradient-driven crystal growth method instead of the conventional sublimation method. The growth occurs in a temperature gradient field where the SiC base substrate is heated to a temperature lower than the melting point of SiC but higher than the sublimation point, enabling controlled crystal growth with reduced defect density while maintaining high productivity.
Solution Approach 2:
The invention creates local quality differences by establishing a temperature gradient across the growth chamber. The SiC base substrate is positioned in a specific temperature zone that optimizes crystal growth conditions, while the temperature varies in different regions to control the growth process and reduce defects in the final substrate.
3Manufacturing precision
If the high temperature CVD method is used to grow SiC substrates, then substrate quality is improved, but diameter expansion is limited and productivity decreases
Solution Approach 1:
The patent fundamentally changes the growth temperature parameters by operating below the melting point of SiC but above the sublimation point, creating a new temperature regime that enables both high-quality crystal growth and faster production rates compared to conventional high temperature CVD methods.
4Manufacturing precision
If multiple apparatus systems are introduced to perform etching and crystal growth separately, then process control is improved, but equipment cost and system complexity increase
Solution Approach 1:
The patent merges the etching apparatus and crystal growth apparatus into a single integrated system. The same chamber and heating mechanism are used to perform both etching (by controlling the temperature gradient direction) and crystal growth, significantly reducing equipment complexity and cost while maintaining precise process control through unified system management.
Solution Approach 2:
The heating apparatus and reaction chamber are designed to serve multiple functions: they can create temperature gradients for etching, maintain temperatures for crystal growth, and control the atmospheric conditions for both processes. This multi-functionality eliminates the need for separate dedicated equipment for each process step.
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 enables the production of high-quality, large-diameter SiC substrates by removing subsurface damaged layers and macro-step bunching, reducing defect density, and eliminating the need for multiple apparatuses, thereby reducing costs and extending the life of SiC materials.
Implementation Method 1
performing heating so as to form a temperature gradient between the SiC base substrate and the SiC material
Implementation Method 2
an etching step of etching a SiC base substrate
Implementation Method 3
a crystal growth step of growing a SiC substrate layer on the SiC base substrate
Implementation Method 4
growing a SiC substrate layer on the SiC base substrate to obtain a SiC substrate body
Data Source
AI summary
The present invention addresses the problem of providing a novel SiC substrate production method. The SiC substrate production method according to the present invention comprises an etching step S10 of etching a SiC base substrate 10, a crystal growth step S20 of growing a SiC substrate layer 13 on the SiC base substrate 10 to produce a SiC substrate body 20, and a peeling step S30 of peeling at least a portion of the SiC substrate body 20 to produce a SiC substrate 30, the method being characterized in that each of the etching step S10 and the crystal growth step S20 is a step of arranging the SiC base substrate 10 and a SiC material 40 so as to face each other and heating the SiC base substrate 10 and the SiC material 40 so as to form a temperature gradient between the SiC base substrate 10 and the SiC material 40.