SiC Substrate Lattice Plane Curvature Compensation
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Solution Overview
Problem
Monocrystalline SiC substrates with homogeneous lattice planes are prone to curvature during epitaxy processes, leading to non-ideal epitaxy conditions and defects in semiconductor components due to temperature-induced expansion differences between the substrate's upper and lower sides.
Innovation Solution
A method is developed to grow SiC volume monocrystals with a non-homogeneous lattice plane course by bending the SiC seed crystal during the heating phase before growth, introducing deliberate deviations in lattice plane orientation that compensate for substrate curvature, resulting in SiC substrates with level lattice planes during epitaxy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If monocrystalline SiC substrates with homogeneous lattice planes are used, then the substrate structure is simple and manufacturing is easier, but the substrate undergoes curvature during epitaxy processes due to temperature-induced expansion differences, leading to non-ideal epitaxy conditions and defects
Solution Approach 1:
The patent applies preliminary action by intentionally introducing a non-homogeneous lattice plane course during the crystal growth phase, before the epitaxy process begins. The lattice planes are designed with a predetermined curvature that will compensate for the thermal expansion curvature occurring during subsequent epitaxy heating, thereby pre-positioning the substrate to achieve level lattice planes under operating conditions
Solution Approach 2:
The patent changes the physical parameter of lattice plane orientation from homogeneous to non-homogeneous during crystal growth. By controlling the crystal growth parameters to create a specific non-uniform lattice structure, the substrate is prepared to undergo controlled curvature during epitaxy that results in level lattice planes under thermal stress, thus improving manufacturing precision without sacrificing ease of production
2Stability of the object's composition
If the SiC substrate has homogeneous lattice planes, then the crystal structure is uniform and simpler to produce, but temperature-induced expansion during epitaxy causes curvature and lattice plane deviation, propagating defects into the epitaxy layer
Solution Approach 1:
The patent applies preliminary anti-action by introducing a deliberate non-homogeneous lattice plane course that acts in opposition to the expected thermal expansion curvature during epitaxy. The initial lattice structure is designed with inverted curvature characteristics that will counterbalance the thermal effects, thereby preventing lattice plane deviation and maintaining reliability of the epitaxy layer
Solution Approach 2:
The patent applies local quality by creating a spatially varying lattice plane orientation within the crystal structure. Different regions of the substrate have deliberately different lattice plane angles, with the center and periphery having specific angular relationships that compensate for local thermal expansion differences during epitaxy, thus ensuring uniform epitaxy layer quality across the entire substrate
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 enables the production of SiC substrates that maintain level lattice planes during epitaxy, enhancing the quality and efficiency of semiconductor component production by minimizing defects and improving epitaxy conditions.
Implementation Method 1
The SiC seed crystal is bent during a heating phase before the beginning of growth
Implementation Method 2
by sublimation of the powdery SiC source material and by transport of the sublimed gaseous components
Implementation Method 3
the SiC volume monocrystal having a central center longitudinal axis grows by deposition out of the SiC growth gas phase onto the SiC seed crystal
Data Source
AI summary
A method is used for producing an SiC volume monocrystal by sublimation growth. During growth, by sublimation of a 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 grows by deposition from the SiC growth gas phase on the SiC seed crystal. The SiC seed crystal is bent during a heating phase before such that an SiC crystal structure with a non-homogeneous course of lattice planes is adjusted, the lattice planes at each point have an angle of inclination relative to the direction of the center longitudinal axis and peripheral angles of inclination at a radial edge of the SiC seed crystal differ in terms of amount by at least 0.05° and at most by 0.2° from a central angle of inclination at the site of the center longitudinal axis.