Heat-Insulating Shield Member for 4H-SiC Crystal Growth
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Solution Overview
Problem
The challenge in increasing the diameter and length of 4H-SiC ingots lies in maintaining a high sublimation rate of the SiC source while avoiding the mixing of 6H-SiC and precipitation on the SiC source surface, which affects growth stability and quality.
Innovation Solution
A heat-insulating shield member with low thermal conductivity, such as carbon fiber or expanded graphite, is used between the SiC source housing and the substrate support to create a vertical temperature difference, reducing the seed crystal's surface temperature and suppressing precipitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the temperature of the SiC source portion is raised to increase the sublimation rate, then the productivity is improved, but the temperature of the seed crystal rises and causes thermal etching and dents
Solution Approach 1:
A heat-insulating shield plate is introduced as an intermediary component between the SiC source portion and the seed crystal. This shield plate has a heat-insulating portion with low thermal conductivity that blocks heat transmission, allowing the source temperature to be raised for higher sublimation rate while preventing the seed crystal from overheating and maintaining its growth surface quality.
Solution Approach 2:
The shield plate structure incorporates a heat-insulating portion with specifically low thermal conductivity in the region facing the seed crystal, while other portions may have different properties. This local differentiation of thermal properties enables selective heat blocking where needed, allowing high source temperature for productivity without compromising seed crystal temperature control for manufacturing precision.
2Quantity of substance
If the diameter of the SiC ingot is enlarged to meet market demand, then the quantity of substance is improved, but the temperature distribution becomes nonuniform causing growth surface defects
Solution Approach 1:
The heat-insulating shield plate acts as a thermal mediator that creates a more uniform temperature distribution across the seed crystal surface. By blocking direct radiant heat and reducing thermal gradients, it enables larger ingot diameters to be grown while maintaining growth surface flatness and preventing thermal etching defects.
Solution Approach 2:
The introduction of the heat-insulating shield plate changes the thermal parameters in the crystal growth system. It modifies the temperature distribution profile by reducing peak temperatures and minimizing radial temperature gradients, thereby enabling stable growth of larger diameter ingots with uniform growth surfaces.
3Manufacturing precision
If a conventional shield plate is used to control temperature distribution, then the growth surface shape is improved, but precipitation occurs on the SiC source surface affecting growth stability
Solution Approach 1:
The heat-insulating shield plate serves as a thermal mediator that decouples the temperature control of the source from the seed crystal. By using materials with low thermal conductivity, it allows the source to be maintained at a higher temperature that prevents precipitation while still protecting the seed crystal from excessive heat, thereby improving both growth stability and 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 approach effectively suppresses precipitation on the SiC source surface and minimizes 6H-SiC contamination, enhancing the growth stability and quality of the 4H-SiC ingot.
Implementation Method 1
A heat-insulating shield member with low thermal conductivity, such as carbon fiber or expanded graphite, is used between the SiC source housing and the substrate support to create a vertical temperature difference
Implementation Method 2
the SiC source portion 102 is heated and sublimed, and SiC source gas is introduced onto the seed crystal 104 and recrystallized on the seed crystal 104 to grow a single crystal 105
Implementation Method 3
the seed crystal 104 avoids directly receiving the radiant heat of the SiC source portion 102 by the shield plate 106
Data Source
AI summary
The present invention provides a heat-insulating shield member, wherein the heat-insulating shield member is arranged and used between a SiC source housing (3) and a substrate support (4) in a single crystal manufacturing apparatus (10), wherein the single crystal manufacturing apparatus (10) comprises a crystal growth container (2) and a heating member (5) arranged on an outer periphery of the crystal growth container (2), wherein the crystal growth container (2) includes the SiC source housing (3) disposed at a lower portion of the apparatus, and the substrate support (4) which is arranged above the SiC source housing (3) and supports a substrate (S) used for crystal growth so as to face the SiC source housing (3), and wherein the single crystal manufacturing apparatus (10) is configured to grow a single crystal (W) from a SiC source (M) on the substrate (S) by sublimating the SiC source (M) from the SiC source housing (3).