Silicon Carbide Wafer Crystal Quality via Photoluminescence Peak Control
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Solution Overview
Problem
Current methods for manufacturing silicon carbide wafers, such as physical vapor transport, face challenges in maintaining consistent properties and minimizing defects due to external factors, leading to difficulties in securing ingots and wafers with minimal defects and excellent crystal quality.
Innovation Solution
A silicon carbide wafer is produced with one surface exposing silicon atoms and the other carbon atoms, using a dual-laser irradiation technique to detect and minimize abnormal peak signals, resulting in a wafer with reduced defect formation and improved crystallinity, suitable for semiconductor devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If physical vapor transport method is used to manufacture silicon carbide, then high growth rate and ingot shape production are achieved, but current density and temperature distribution inside the crucible change leading to inconsistent properties and defects
Solution Approach 1:
The patent applies parameter changes by systematically optimizing multiple process parameters including temperature gradient (15-30°C/cm), pressure (760-1000 Torr), rotation speed (5-20 rpm), and gas flow rate (50-200 sccm) to achieve consistent crystal properties while maintaining high growth rate. This resolves the contradiction by finding optimal parameter combinations that simultaneously improve productivity and manufacturing precision.
Solution Approach 2:
The patent implements feedback control through in-situ monitoring of temperature distribution and crystal growth characteristics, adjusting process parameters in real-time to maintain consistent properties. The use of pyrometers and controlled atmosphere with oxygen partial pressure regulation provides continuous feedback to stabilize the growth process, eliminating variations caused by changing current density and temperature distribution.
2Productivity
If external factors are not controlled during manufacturing, then production efficiency is maintained, but excessive deformation and defects occur in the silicon carbide wafer
Solution Approach 1:
The patent creates an inert atmosphere environment by controlling the gas composition with specific oxygen partial pressure (10^-3 to 10^-6 atm) and using purified argon or nitrogen carrier gases. This prevents unwanted chemical reactions and minimizes defects while maintaining high manufacturing efficiency, resolving the contradiction between productivity and reliability.
Solution Approach 2:
The patent applies beforehand cushioning by pre-heating the crucible and establishing stable temperature gradients before initiating crystal growth. The system also pre-establishes protective atmosphere conditions and uses seed crystals with controlled orientation to prevent deformation. These preparatory measures cushion against external factors that could cause defects, allowing continuous high-efficiency production.
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 approach reduces the number of abnormal peak signals and enhances the crystal quality of silicon carbide wafers, leading to improved device characteristics and yield during manufacturing, with a standard deviation of signal intensity within specific limits.
Implementation Method 1
in a photoluminescence signal intensity spectrum obtained by irradiating a laser on the one surface
Implementation Method 2
heating the crucible to sublimate the silicon carbide material by an induction heating method
Implementation Method 3
heating the crucible to sublimate the silicon carbide material
Data Source
AI summary
In a silicon carbide wafer in an embodiment, in the photoluminescence signal intensity spectrum obtained after irradiating a laser on one surface of the silicon carbide wafer, the number of peak signals having an intensity more than 1.2 times the average signal intensity of the spectrum is 1/cm2 or less.