Epitaxial Wafer Gas Evacuation Pressure Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing method for manufacturing epitaxial wafers faces issues with particle stirring and insufficient evacuation, leading to deteriorated Light Point Defect (LPD) quality due to inconsistent differential pressure between the reaction chamber and the transfer chamber.
Innovation Solution
An apparatus and method that control the gas evacuation in the reaction chamber and wafer transfer chamber to manage pressure differentials, using specific evacuation amounts and pressures during epitaxial film formation, wafer loading/unloading, and purge processes to minimize particle attachment and enhance LPD quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the differential pressure between the reaction chamber and the transfer chamber is increased, then the evacuation of particles is improved, but particles are readily stirred up when the gate valve is opened
Solution Approach 1:
The patent applies dynamics by making the evacuation amount adjustable and variable during different process stages. The evacuation amount is dynamically changed based on the operational phase: a first evacuation amount during epitaxial film formation, a second smaller amount during wafer loading/unloading, and a third larger amount during purge processes. This dynamic adjustment resolves the contradiction by optimizing particle evacuation while minimizing particle stirring during gate valve operations.
Solution Approach 2:
The patent changes the parameter of evacuation amount from a fixed value to a variable parameter with at least three distinct levels. By controlling the evacuation amount to be different during various process stages (film formation, wafer handling, and purge), the system optimizes the balance between particle evacuation efficiency and particle stirring prevention, thereby improving LPD quality.
2Object-affected harmful factors
If the differential pressure is set high to evacuate particles effectively, then particle removal is improved, but particle contamination occurs during wafer transfer
Solution Approach 1:
The patent implements periodic action by alternating between different evacuation amounts at different stages of the process. The system periodically switches between a higher evacuation amount (for particle removal) and a lower evacuation amount (for particle containment during transfer). This periodic variation in evacuation intensity ensures effective particle removal while preventing contamination during critical wafer handling phases.
Solution Approach 2:
The patent applies preliminary action by performing a purge process with a third evacuation amount (larger than the first) after epitaxial film formation and before wafer unloading. This preliminary high-evacuation action removes particles generated during film formation before the gate valve is opened, thereby preventing particle contamination during the subsequent wafer transfer operation.
3Object-generated harmful factors
If the evacuation pressure is lowered to reduce particle stirring, then particle stirring is reduced, but particle evacuation becomes insufficient
Solution Approach 1:
The patent resolves this contradiction through dynamic control of the evacuation amount. Instead of using a single fixed evacuation level, the system dynamically adjusts the evacuation amount based on process needs: using a larger evacuation amount (third amount) during purge processes to ensure adequate particle evacuation, and a smaller evacuation amount (second amount) during wafer loading/unloading to minimize particle stirring. This dynamic approach ensures both effective evacuation and minimal stirring at different stages.
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 evacuation and pressure management effectively reduce particle flow and improve LPD quality by suppressing dust attachment during wafer handling and ensuring thorough evacuation post-film formation.
Implementation Method 1
the pressure of a nitrogen gas atmosphere in the transfer chamber is made higher than the pressure of a hydrogen gas atmosphere in the reaction chamber by 0.067 kPa to 0.267 kPa (0.5 Torr to 2 Torr)
Implementation Method 2
an epitaxial growth apparatus is used to form silicon epitaxial films on the top surfaces of silicon wafers
Implementation Method 3
a silicon epitaxial film is formed on the surface of the silicon wafer
Data Source
AI summary
The amount of gas evacuation from a reaction chamber of an apparatus for manufacturing epitaxial wafers is controlled to any one of: a first amount of gas evacuation when an epitaxial film formation process is performed in the reaction chamber; a second amount of gas evacuation smaller than the first amount of gas evacuation when a gate valve is opened to load or unload a wafer between the reaction chamber and a wafer transfer chamber; and a third amount of gas evacuation larger than the first amount of gas evacuation until a purge process for a gas in the reaction chamber is completed after the epitaxial film formation process is completed in the reaction chamber.