Adhesive-Free Silicon Focus Ring for Plasma Uniformity
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Solution Overview
Problem
Existing focus rings for plasma processing apparatuses face challenges with material waste, increased manufacturing costs, and issues with abnormal electric discharge and thermal non-uniformity due to adhesive degradation and inaccurate processing of arc-shaped members.
Innovation Solution
A focus ring formed from silicon arc-shaped members and connecting members without adhesive, where the members engage with convex and concave fitting portions to ensure uniform contact with the pedestal and prevent gas emission, maintaining coplanar surfaces and uniform plasma environment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single crystalline silicon ingot with outer diameter greater than substrate diameter is prepared to manufacture a focus ring, then the focus ring can be manufactured, but it is difficult to manufacture the ingot with greater outer diameter and material waste increases causing manufacturing cost increase
Solution Approach 1:
The focus ring is divided into multiple arc-shaped members that can be manufactured separately from smaller silicon ingots or wafers, then assembled together to form the complete ring structure. This eliminates the need to manufacture a single large-diameter ingot and reduces material waste significantly.
2Ease of manufacture
If arc-shaped members are connected using adhesive, then the focus ring can be assembled, but adhesive degradation causes abnormal electric discharge and gas emission
Solution Approach 1:
The adhesive bonding system is replaced with a mechanical connection system using convex and concave fitting portions. The arc-shaped members are connected through precise mechanical interlocking without any adhesive, eliminating the source of gas emission and abnormal electric discharge while maintaining structural integrity.
3Ease of manufacture
If arc-shaped members are connected without precise processing, then assembly is easier, but inaccurate processing causes thermal non-uniformity due to non-uniform contact with pedestal
Solution Approach 1:
The connection structure incorporates localized convex and concave fitting portions that concentrate the contact points. These localized features ensure precise alignment and uniform contact with the pedestal at critical areas, while the overall assembly remains relatively simple. The fitting portions are designed with specific geometries to guarantee proper positioning and thermal contact.
Data Source
AI summary
There is provided a focus ring formed without an adhesive that can suppress abnormal electric discharge and obtain uniform plasma environment in a circumferential direction in a plasma processing apparatus. The focus ring includes a plurality of arc-shaped members and a plurality of connecting members connecting the plurality of the arc-shaped members to form a ring shape without an adhesive, and is formed such that a thickness between an upper surface of the connecting member and a bottom surface of a concave fitting portion of the connecting member is greater than a thickness between an upper surface of the arc-shaped member and a bottom surface of a second depression of the arc-shaped member.