Silicon Carbide Wafer Processing for Low-Warpage, Low-Defect Surfaces
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Solution Overview
Problem
The existing methods for producing silicon carbide wafers through physical vapor transport often result in warpage and distortion due to variations in crucible heating, leading to increased defects in the ingots and subsequent wafers, which negatively impact the quality and yield of semiconductor devices.
Innovation Solution
A wafer manufacturing method involving a reactor with a heat insulating material of specific density, controlled temperature and pressure, and a two-step grinding process with grinding wheels of varying particle sizes to minimize scratches and particles, followed by chemical mechanical polishing to produce high-quality silicon carbide wafers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If physical vapor transport is used to grow silicon carbide ingots, then fast growth and high productivity are achieved, but warpage and distortion occur due to uneven heating, increasing defect density
Solution Approach 1:
A heat insulating material is introduced as an intermediary between the heating source and the crucible to mediate the heat transfer process. This material distributes thermal energy uniformly across the crucible surface, preventing localized overheating and the resulting warpage and distortion of the silicon carbide ingot during fast growth
2Temperature
If induction heating is applied to the crucible, then efficient heating and high temperature growth are achieved, but non-uniform temperature distribution causes warpage and distortion
Solution Approach 1:
The heat insulating material is applied specifically to the outer surface of the crucible where non-uniform heating occurs. This localized treatment addresses the temperature distribution problem at the heat transfer interface without altering the overall induction heating process, maintaining high heating efficiency while achieving uniform temperature distribution
3Manufacturing precision
If conventional grinding is performed on the wafer surface, then material removal and planarization are achieved, but scratches and particles are generated, deteriorating surface quality
Solution Approach 1:
The particle size of the grinding wheel is changed from conventional coarse particles to fine particles ranging from 1000 mesh to 10000 mesh. This parameter change allows effective material removal and planarization while minimizing the generation of scratches and particles on the wafer surface, thereby improving surface quality
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 reduces warpage and distortion, minimizes defects, and enhances the quality and yield of silicon carbide wafers, resulting in improved semiconductor device performance.
Implementation Method 1
a heat insulating material surrounds an outer surface of the reactor
Implementation Method 2
the crucible is heated by induction to sublimate the raw material
Implementation Method 3
controlling a temperature, a pressure, and an atmosphere of the internal space to sublimate the raw material
Implementation Method 4
the planarizing of the wafer comprises performing a first processing operation with a first grinding wheel
Data Source
AI summary
A wafer manufacturing method, an epitaxial wafer manufacturing method, and a wafer and epitaxial wafer manufactured thereby, are provided. The wafer manufacturing method enables the manufacture of a wafer with a low density of micropipe defects and minimum numbers of particles and scratches. The epitaxial wafer manufacturing method enables the manufacture of an epitaxial wafer that has low densities of defects such as downfall, triangular, and carrot defects, exhibits excellent device characteristics, and improves the yield of devices.