SiC Vapor Growth Gas Ratio Control for Surface Defect Reduction
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Solution Overview
Problem
Defects such as pits or bumps occur on the surface of epitaxial single crystal films formed through vapor phase growth, which affect the quality of semiconductor films.
Innovation Solution
A vapor phase growth apparatus and method that control the ratio of chlorine to silicon in the source and purge gases to enhance film quality, involving a reactor with specific gas flow paths and a control unit to manage gas supply ratios and flow rates during different growth periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional vapor phase growth is used, then film formation is achieved, but defects such as pits or bumps occur on the film surface
Solution Approach 1:
The patent applies parameter changes by precisely controlling the ratio of chlorine to silicon in the process gas. Specifically, the chlorine-to-silicon ratio is maintained at 30 or more during the initial growth period, and then adjusted in subsequent periods. This chemical parameter control prevents defect formation and improves film surface quality by optimizing the vapor phase growth conditions.
Solution Approach 2:
The patent implements periodic action by dividing the vapor phase growth process into multiple time periods with different gas flow rate conditions. In the first period, a specific chlorine-to-silicon ratio is maintained to prevent defects. In subsequent periods, the gas flow rate is adjusted to optimize film growth. This temporal segmentation allows different process parameters to be optimized for different stages of film formation.
2Productivity
If gas flow rate is increased to improve film growth, then productivity increases, but defect formation may increase
Solution Approach 1:
The patent applies periodic action by segmenting the growth process into periods with different gas flow rates. During the first period, the gas flow rate is controlled to maintain a chlorine-to-silicon ratio of 30 or more, preventing defect formation. In subsequent periods, the gas flow rate is increased to improve productivity. This temporal differentiation allows both high quality and high productivity to be achieved at different stages.
Solution Approach 2:
The patent uses parameter changes by dynamically adjusting the gas flow rate based on the growth stage. The chlorine-to-silicon ratio is maintained at 30 or more during the initial period to ensure high film quality. After the first period, the gas flow rate is increased to boost productivity. This staged parameter adjustment resolves the contradiction between quality and productivity.
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 controlled gas ratio and flow rate strategy reduces defects, improving the quality and integrity of silicon carbide films formed on substrates.
Implementation Method 1
a vapor phase growth apparatus and method for forming a silicon carbide film on a substrate placed on a holder provided in a reactor
Implementation Method 2
While heating the substrate, a process gas containing the raw material of a film is supplied to the reactor through a gas introduction unit above the reactor. A thermal reaction of the process gas occurs on the surface of the substrate
Data Source
AI summary
A vapor phase growth apparatus according to embodiments includes: a reactor; a holder placing a substrate; a source gas flow path supplying a first source gas containing silicon and chlorine; a purge gas flow path supplying a purge gas containing chlorine and hydrogen; and a control unit controlling supply of the first source gas and the purge gas. The control unit controls the ratio of the sum of a second amount of substance being the amount of substance of chlorine in the first source gas, and a third amount of substance being the amount of substance of chlorine in the purge gas, to a first amount of substance being the amount of substance of silicon in the first source gas, to be 30 or more in a first period. The control unit increases a flow rate of the first source gas in a second period after the first period.