Focus Ring Thermal Conductive Sheet Vulcanization
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Solution Overview
Problem
In plasma processing apparatuses, the thermal conductivity between the focus ring and the mounting table is poor due to vacuum insulation, leading to inadequate cooling of the focus ring, which affects etching uniformity and efficiency, and the adhesivity of thermally conductive sheets is challenging to maintain, causing detachment issues during replacement.
Innovation Solution
A focus ring with a thermally conductive sheet fixed as a single unit using unvulcanized rubber as an adhesive, ensuring effective heat transfer without mechanical pressing units, and maintaining adhesivity through vulcanization at a factory level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a vacuum insulating layer is formed between the focus ring and the mounting table to maintain vacuum environment, then vacuum insulation is achieved, but thermal conductivity between the focus ring and mounting table becomes poor, leading to inadequate cooling of the focus ring
Solution Approach 1:
A thermally conductive sheet is introduced as an intermediary component between the focus ring and the mounting table. This sheet has high thermal conductivity to facilitate heat transfer from the focus ring to the mounting table, while maintaining the vacuum insulation properties of the surrounding environment. The thermally conductive sheet acts as a heat conduction path that does not compromise the vacuum seal.
Solution Approach 2:
The mounting table structure employs composite materials: a vacuum insulating layer for maintaining vacuum environment and a thermally conductive sheet for heat transfer. This composite structure allows simultaneous achievement of vacuum insulation and effective thermal conduction, resolving the contradiction between maintaining vacuum and cooling the focus ring.
2Temperature
If a thermally conductive sheet is inserted between the focus ring and the mounting table to improve cooling, then thermal conductivity is improved, but adhesivity becomes challenging to maintain, causing detachment issues during focus ring replacement
Solution Approach 1:
The patent replaces mechanical pressing units with a chemical bonding mechanism. Instead of using mechanical pressure to maintain adhesivity, a bonding agent is applied to create a chemical bond between the thermally conductive sheet and the mounting table, providing reliable adhesion without requiring mechanical pressing mechanisms.
3Reliability
If mechanical pressing units are used to improve adhesivity of the thermally conductive sheet, then adhesivity is improved, but device complexity increases and the pressing units may break when detaching the focus ring
Solution Approach 1:
The patent eliminates mechanical pressing units by substituting them with a chemical bonding agent. This replacement simplifies the device structure, removes the complexity of mechanical pressing mechanisms, and avoids the risk of mechanical unit breakage during focus ring detachment, while still providing reliable adhesion through chemical bonding.
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 ensures sufficient thermal conductivity and adhesivity, allowing for consistent heat transfer and preventing detachment issues, thus improving etching uniformity and extending the focus ring's lifespan without the need for mechanical pressing units.
Implementation Method 1
a thermally conductive sheet having good thermal conductivity is inserted between the focus ring and the top surface of the outer peripheral portion of the mounting table
Implementation Method 2
coating an unvulcanized rubber, a material of which is as same as a material of the thermally conductive sheet, on one surface of the thermally conductive sheet, bringing said one surface into contact with the back surface of the annular main body, and heating the thermally conductive sheet and the annular main body to vulcanize the thermally conductive sheet and to adhere the thermally conductive sheet to the back surface of the annular main body
Implementation Method 3
a high frequency voltage is applied to the processing chamber under a vacuum environment. Accordingly, a plasma is generated in the processing chamber, and, e.g., etching of the substrate is carried out
Data Source
AI summary
A focus ring to be detachably attached to a top surface of an outer peripheral portion of a mounting table in a processing chamber, includes: an annular main body having a back surface to be attached to the top surface of the outer peripheral portion of the mounting table. And a thermally conductive sheet fixed to the annular main body, the thermally conductive sheet being interposed between the annular main body and the top surface of the outer peripheral portion of the mounting. The thermally conductive sheet is fixed as one unit to the annular main body by coating an unvulcanized rubber on one surface of the thermally conductive sheet, bringing said one surface into contact with the annular main body, and heating the thermally conductive sheet and the annular main body to vulcanize and to adhere the thermally conductive sheet to the annular main body.