Wafer Carrier Cleaning in Vapor Deposition to Prevent Backside Defects
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Solution Overview
Problem
Vapor deposition devices used in manufacturing epitaxial wafers face issues with contamination and defects such as particle deposition and adhesion scratches on the back surface of wafers due to polysilicon and metal impurities from the susceptor, which deteriorate the electrical characteristics of the wafers.
Innovation Solution
A vapor deposition method and device that uses a ring-shaped carrier to transport wafers, with a polysilicon film formed on the susceptor to prevent contamination and adhesion scratches, while ensuring the carrier surface remains free of polysilicon film to prevent back surface deposition and scratches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a polysilicon film is formed on the susceptor to prevent contamination, then particle contamination is suppressed, but deposition on the back surface of the wafer occurs
Solution Approach 1:
The invention applies different surface treatments to different components: the susceptor is coated with a polysilicon film to prevent particle contamination, while the carrier surface is kept free of polysilicon film to prevent back surface deposition. This local differentiation of surface properties resolves the contradiction between preventing contamination and avoiding unwanted deposition.
2Object-affected harmful factors
If the carrier surface is coated with polysilicon film to prevent contamination, then particle contamination is reduced, but adhesion scratches occur on the wafer
Solution Approach 1:
The invention selectively applies the polysilicon film coating only to the susceptor while deliberately excluding the carrier surface from coating. This local quality differentiation prevents both adhesion scratches on the wafer (by keeping the carrier surface clean) and maintains particle contamination protection (through the susceptor coating).
3Productivity
If repeated production is performed without cleaning, then productivity is maintained, but deposits accumulate on the carrier and susceptor causing quality deterioration
Solution Approach 1:
The invention performs cleaning of the carrier and susceptor at predetermined intervals during the production process, and forms a fresh polysilicon film on the susceptor after cleaning. This preliminary maintenance action prevents deposit accumulation that would otherwise deteriorate wafer quality, while the systematic approach minimizes impact on overall 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 solution effectively suppresses contamination by particles and adhesion scratches on the wafer surface, improving the quality of the epitaxial wafers by maintaining a clean carrier surface and utilizing a polysilicon film on the susceptor to prevent contamination.
Implementation Method 1
forming a polysilicon film on the surface of the susceptor
Implementation Method 2
the particles float in the reaction chamber and the transfer chamber by the hot air in the reaction chamber
Data Source
AI summary
Using the first robot, the carrier standing by in the load lock chamber is deposited into the reaction chamber without mounting the wafer before processing, and cleaning gas is supplied while the reaction chamber is maintained at a predetermined cleaning temperature, and the carrier that has been cleaned in the reaction chamber is transferred to the load lock chamber using the first robot. The carrier and susceptor are cleaned at a predetermined frequency. After that, the carrier is carried out from the reaction chamber, and the reaction gas is supplied to the reaction chamber to form a polysilicon film on the surface of the susceptor.