SiC Seed Crystal Heating for Homogeneous Lattice Planes
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Solution Overview
Problem
The production of high-quality SiC substrates with uniform lattice plane orientation is challenging due to local deviations in the crystal structure, leading to defects in the epitaxy layer and poor performance of semiconductor components.
Innovation Solution
A method involving the use of an SiC seed crystal with a homogeneous lattice plane orientation, heated without bending, is introduced into a growth crucible where powdery SiC source material is sublimated to form a growth gas phase, resulting in an SiC volume monocrystal with a central longitudinal axis. The seed crystal's orientation is maintained during growth, ensuring a homogeneous lattice plane course in the produced SiC volume monocrystal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional SiC volume monocrystal production methods are used, then substrates can be produced, but local deviations from optimal orientation occur in the crystal structure leading to defects in the epitaxy layer
Solution Approach 1:
The seed crystal is pre-heated in a controlled manner before the main crystal growth process begins. This preliminary heating action prepares the seed crystal's lattice structure to maintain optimal orientation during subsequent growth, preventing local deviations that would otherwise propagate into the epitaxy layer and cause defects.
Solution Approach 2:
The heating parameters are specifically controlled during the pre-heating phase, with the heating rate and temperature profile optimized to prevent thermal bending of the seed crystal. By carefully managing these thermal parameters, the lattice plane orientation uniformity is maintained throughout the crystal growth process, ensuring high reliability of the resulting epitaxy layer.
2Productivity
If the SiC seed crystal is heated rapidly to increase production speed, then growth time is reduced, but the seed crystal bends during heating causing lattice plane deviations
Solution Approach 1:
A controlled pre-heating phase is implemented before the main crystal growth begins. This preliminary action allows the seed crystal to gradually reach the required temperature without sudden thermal gradients that would cause bending, thus maintaining lattice plane orientation while still enabling subsequent rapid growth.
Solution Approach 2:
The heating process is divided into distinct periodic phases: an initial slow heating phase to prevent bending, followed by a maintained temperature phase for stable crystal growth. This periodic heating strategy balances the need for production speed with the requirement for precise lattice plane orientation.
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 approach produces SiC substrates with a highly homogeneous crystal structure, providing ideal conditions for epitaxy and enhancing the quality of semiconductor components by minimizing defects and improving their performance.
Implementation Method 1
by sublimation of the powdery SiC source material and by transport of the sublimated gaseous components into the crystal growth region
Implementation Method 2
the SiC volume monocrystal having a central center longitudinal axis grows by deposition from the SiC growth gas phase on the SiC seed crystal
Implementation Method 3
The SiC seed crystal is heated substantially without bending during a heating phase before the beginning of growth
Data Source
AI summary
A method is used for producing an SiC volume monocrystal by sublimation growth. Before the beginning of growth, an SiC seed crystal is arranged in a crystal growth region of a growth crucible and powdery SiC source material is introduced into an SiC storage region of the growth crucible. During the growth, by sublimation of the powdery SiC source material and by transport of the sublimated gaseous components into the crystal growth region, an SiC growth gas phase is produced there. The SiC volume monocrystal having a central center longitudinal axis grows by deposition from the SiC growth gas phase on the SiC seed crystal. The SiC seed crystal is heated substantially without bending during a heating phase before the beginning of growth, so that an SiC crystal structure with a substantially homogeneous course of lattice planes is provided in the SiC seed crystal.