Composite Edge Ring Structure for Uniform Plasma Etching
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Solution Overview
Problem
Substrate processing apparatuses face challenges in achieving uniform etching of the edge region due to electric field distortion caused by plasma discontinuity, leading to non-uniform etching rates and critical-dimension uniformity issues.
Innovation Solution
The apparatus incorporates a susceptor with an inner edge ring made of semiconductor material and an outer edge ring made of insulator material, where the outer edge ring has an overhang extending onto the inner edge ring, and a movable edge ring system to maintain a uniform electric field and prevent ion tilting during the etching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional single-material edge rings are used, then the structure is simple, but the electric field uniformity deteriorates due to plasma discontinuity
Solution Approach 1:
The edge ring is constructed using composite materials with different dielectric constants - an inner edge ring portion and an outer edge ring portion made of different materials. This composite structure allows optimization of the electric field distribution by selecting materials with appropriate dielectric properties, thereby improving etching uniformity across the substrate while managing the complexity through a modular design approach.
2Manufacturing precision
If edge rings are used to improve electric field uniformity, then etching uniformity improves, but the edge rings wear out faster and require frequent replacement
Solution Approach 1:
The edge ring system is designed with movable and replaceable components. The outer edge ring portion can be independently replaced when worn, while the inner edge ring portion remains in place. This dynamic replacement strategy extends the overall service life of the edge ring assembly by allowing selective replacement of only the worn outer portion rather than the entire edge ring structure.
3Manufacturing precision
If the outer edge ring is made higher than the inner edge ring, then plasma distribution improves, but the structure becomes more complex
Solution Approach 1:
The edge ring structure implements local quality by creating different heights for the inner and outer edge ring portions. The outer edge ring portion is positioned at a higher level than the inner edge ring portion, creating a stepped configuration. This local variation in height is specifically designed to optimize plasma distribution and electric field uniformity in the edge region of the substrate, applying structural complexity only where it provides the greatest benefit.
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 enhances the uniformity of the electric field, improves the etch rate, and maintains critical-dimension uniformity of patterns in the edge region of the substrate by planarizing and stabilizing the electric field, thereby extending the use period of the edge rings and ensuring consistent plasma distribution.
Implementation Method 1
the etching of an edge region of a substrate may not be completely uniform due to the distortion of an electric field
Implementation Method 2
plasma discontinuity
Data Source
AI summary
A substrate processing apparatus including a process chamber; a susceptor in the process chamber; and an inner edge ring and an outer edge ring on the susceptor, wherein the inner edge ring includes a semiconductor, the outer edge ring includes an insulator, an upper surface of the outer edge ring is at a higher level than an upper surface of the inner edge ring, and the outer edge ring has an overhang extending onto the inner edge ring.