Bevel Edge Etching via Segmented Gas Flow and Inert Barrier
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Solution Overview
Problem
As feature sizes on wafers decrease, cleaning the edge region becomes increasingly difficult due to the use of corrosive chemistries that can harm the wafer's center region, necessitating a method to clean the bevel edge without affecting the center.
Innovation Solution
A method and system for etching the edge of a substrate involve flowing an inert gas into the center region and a mixture of inert and processing gases over the edge region, using annular electrodes to maintain a constant mass fraction of processing gas at the edge while preventing diffusion into the center, thereby protecting the center region from harmful plasma species.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If corrosive processing gases are used to clean the edge region, then cleaning effectiveness is improved, but the center region of the wafer is damaged by harmful plasma species
Solution Approach 1:
The gas distribution system is segmented into multiple zones: a center region gas inlet supplying inert gas to the center region, and an edge region gas inlet supplying processing gas to the edge region. This spatial segmentation allows corrosive processing gases to clean the edge while inert gas protects the center region from harmful plasma species
Solution Approach 2:
Different gas compositions are supplied to different regions of the wafer. The edge region receives corrosive processing gases for effective cleaning, while the center region receives inert gas to prevent damage. This local differentiation of gas quality enables simultaneous edge cleaning and center protection
2Manufacturing precision
If processing gas flow is increased to maintain constant mass fraction at the edge, then etch rate control is improved, but gas diffusion into the center region increases
Solution Approach 1:
An inert gas is introduced as an intermediary substance between the processing gas at the edge and the center region. This inert gas acts as a barrier that prevents processing gas diffusion into the center while allowing the processing gas to maintain its constant mass fraction and effective etch rate at the edge region
3Productivity
If feature sizes are reduced to increase device density, then productivity is improved, but edge cleaning difficulty increases due to smaller edge exclusion zone
Solution Approach 1:
The gas distribution system segments the wafer processing area into distinct edge and center zones with separate gas supply pathways. This segmentation enables targeted cleaning of the edge region where contaminants are most critical for small features, while protecting the center region, thereby enabling effective edge cleaning even as the edge exclusion zone shrinks with smaller features
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 effectively controls the etch rate at the edge while safeguarding the center region from corrosive chemicals, ensuring precise cleaning without damaging the wafer's center, even with the use of corrosive processing gases.
Implementation Method 1
striking a plasma in the edge region, wherein the flow of the inert gas and the flow of the mixture maintain a mass fraction of the processing gas substantially constant
Data Source
AI summary
A method for etching a bevel edge of a substrate in a processing chamber is provided. The method includes flowing an inert gas into a center region of the processing chamber defined above a center region of the substrate and flowing a mixture of an inert gas and a processing gas over an edge region of the substrate. The method further includes striking a plasma in the edge region, wherein the flow of the inert gas and the flow of the mixture maintain a mass fraction of the processing gas substantially constant. A processing chamber configured to clean a bevel edge of a substrate is also provided.