Silicon Carbide Epitaxial Substrate Growth Rate and Uniformity Control
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Solution Overview
Problem
Current methods for manufacturing silicon carbide epitaxial substrates face challenges in achieving rapid growth rates while maintaining excellent in-plane uniformity of carrier concentration and surface flatness, particularly when using large-scale manufacturing apparatuses, as increasing growth rates often deteriorates surface flatness and can result in average carrier concentrations falling outside required ranges.
Innovation Solution
The method involves controlling the flow rates of silane, hydrogen, and ammonia within specific ranges, where the silane flow rate divided by hydrogen flow rate and ammonia flow rate fall within a hexagonal region defined by specific coordinates, to achieve rapid growth of silicon carbide layers with improved in-plane uniformity and surface flatness, even when using large manufacturing apparatuses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the growth rate of silicon carbide layer is increased to improve productivity, then the manufacturing efficiency is improved, but the surface flatness and in-plane uniformity of carrier concentration deteriorate
Solution Approach 1:
The patent applies parameter changes by precisely controlling the flow rates of silane, ammonia, and hydrogen within specific ranges, and by controlling the ratio of silane flow rate to hydrogen flow rate within a predetermined range. These parameter adjustments enable rapid layer growth while maintaining surface flatness and carrier concentration uniformity, resolving the contradiction between productivity and manufacturing precision.
2Productivity
If large-scale manufacturing apparatuses are used to increase production capacity, then the productivity is improved, but the control over carrier concentration uniformity and surface flatness becomes more difficult
Solution Approach 1:
The patent controls the flow rates of silane, ammonia, and hydrogen within specific ranges, and maintains the silane flow rate to hydrogen flow rate ratio within a predetermined range. These parameter adjustments enable rapid layer growth while maintaining surface flatness and carrier concentration uniformity, resolving the contradiction between productivity and manufacturing precision.
Solution Approach 2:
The patent establishes specific flow rate ranges and ratios that create a self-regulating system, where the controlled parameters feedback to maintain optimal growth conditions. This feedback mechanism ensures consistent surface flatness and carrier concentration uniformity even in large-scale manufacturing apparatuses with higher production capacity.
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 rapid growth of silicon carbide layers with enhanced in-plane uniformity of carrier concentration and surface flatness, maintaining average carrier concentrations within the required range, and reduces variation in carrier concentration across multiple substrates during batch processing.
Implementation Method 1
A silicon carbide layer is formed on the first main surface by supplying a mixed gas including silane, ammonia and hydrogen to the reaction chamber
Data Source
AI summary
A first main surface is a (000-1) plane or a plane inclined by an angle of less than or equal to 8° relative to the (000-1) plane. A reaction chamber has a cross-sectional area of more than or equal to 132 cm2 and less than or equal to 220 cm2 in a plane perpendicular to a direction of movement of a mixed gas. When an X axis indicates a first value and a Y axis indicates a second value, the first value and the second value fall within a hexagonal region surrounded by first coordinates, second coordinates, third coordinates, fourth coordinates, fifth coordinates and sixth coordinates in XY plane coordinates, where the first coordinates are (0.038, 0.0019), the second coordinates are (0.069, 0.0028), the third coordinates are (0.177, 0.0032), the fourth coordinates are (0.038, 0.0573), the fifth coordinates are (0.069, 0.0849), and the sixth coordinates are (0.177, 0.0964).