SiC CVD Protrusion Gas Flow Control
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Solution Overview
Problem
Existing SiC chemical vapor deposition apparatuses face challenges in evenly supplying raw material gases to SiC wafers due to gas diffusion towards the periphery of the processing chamber, leading to uneven film thickness and potential wafer surface defects.
Innovation Solution
The apparatus incorporates a protrusion on the side wall of the furnace body to adjust the flow of raw material gases, converting it into a laminar flow and preventing convective flow, which is achieved by positioning a first hole for gas introduction, a second hole for purge gas entry, and a third hole for gas discharge, with the protrusion controlling the flow path to ensure even gas distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a raw material gas is supplied to a processing chamber using conventional introduction ports, then gas introduction is achieved, but gas diffuses towards the periphery of side walls causing uneven supply to the wafer
Solution Approach 1:
The introduction port is divided into multiple segments: a main body portion and a protruding portion that extends toward the wafer. This segmentation allows the gas flow to be divided and directed more precisely toward the wafer surface, preventing diffusion toward side walls and improving uniformity of gas supply across the wafer.
Solution Approach 2:
The protruding portion of the introduction port is specifically designed to extend closer to the wafer surface than the main body, creating a localized region where gas is introduced directly above the wafer. This local modification ensures concentrated gas supply at the critical location while preventing peripheral diffusion.
2Quantity of substance
If gas flow rate is increased to ensure sufficient supply to the wafer, then more raw material reaches the wafer, but convective flow occurs causing deposit re-adhesion and wafer surface defects
Solution Approach 1:
The protruding portion of the introduction port performs preliminary action by directing gas flow onto the wafer surface before the gas can diffuse and cause convective flow. This pre-positioning of gas introduction ensures that the gas reaches the wafer efficiently without triggering harmful convective patterns that would cause deposit re-adhesion.
Solution Approach 2:
The protruding portion acts as an intermediary structure between the main gas supply and the wafer surface. It mediates the gas flow by channeling it directly onto the wafer in a controlled manner, preventing the gas from causing convective flow that would lead to wafer surface defects while still ensuring sufficient gas supply.
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 configuration allows for efficient and uniform supply of raw material gases to the SiC wafer, reducing wafer surface defects and improving the quality of the SiC epitaxial film by preventing gas adhesion on the side walls and enhancing in-plane carrier concentration evenness.
Implementation Method 1
a protrusion that protrudes towards the growth space from a lower end of the second hole to adjust a flow of the raw material gas
Implementation Method 2
prevents a convective flow of gas or an uneven dynamic pressure in a processing chamber
Implementation Method 3
the gas may be diffused towards the periphery of side walls of the processing chamber
Implementation Method 4
the SiC epitaxial wafer is produced by growing a SiC epitaxial film, which acts as an active region of a SiC semiconductor device, by chemical vapor deposition (CVD) on the substrate
Data Source
AI summary
Provided is a SiC chemical vapor deposition apparatus including: a furnace body inside of which a growth space is formed; and a placement table which is positioned in the growth space and has a placement surface on which a SiC wafer is placed, in which the furnace body comprises a first hole which is positioned on an upper portion which faces the placement surface and through which a raw material gas is introduced into the growth space, a second hole which is positioned on a side wall of the furnace body and through which a purge gas flows into the growth space, a third hole which is positioned on the side wall of the furnace body at a lower position than the second hole and discharges the gases in the growth space, and a protrusion which is protrudes towards the growth space from a lower end of the second hole to adjust a flow of the raw material gas.