Composite Showerhead Electrode Elastomeric Bonding
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Solution Overview
Problem
Plasma processing apparatuses face challenges with particulate contamination and short lifetimes of consumable parts, such as silicon electrodes, leading to high costs and defects in semiconductor fabrication due to erosion and mismatched thermal expansion coefficients between materials.
Innovation Solution
A composite showerhead electrode assembly with a backing plate and electrode plate bonded using an elastomeric sheet adhesive, allowing for movement due to thermal expansion mismatch and minimizing contamination by controlling gas passage flow and using thermally conductive, electrically conductive fillers to enhance conductivity and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a composite showerhead electrode assembly is used to accommodate thermal expansion mismatch, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent employs an elastomeric bonding layer as a flexible intermediate structure between the electrode and backing plate. This thin film accommodates thermal expansion differences through its elastic properties, allowing the assembly to withstand temperature cycling without failure while maintaining a relatively simple overall structure.
Solution Approach 2:
The showerhead electrode assembly uses composite construction with different materials (electrode material, elastomeric bonding layer, backing plate material) selected for their specific properties. This composite approach allows each layer to perform its function optimally while collectively resolving the thermal expansion mismatch problem.
2Productivity
If gas passages are maintained unobstructed, then productivity is improved, but manufacturing precision is worsened
Solution Approach 1:
The gas passage system is segmented into multiple components (electrode with gas passages, backing plate with gas passages, and elastomeric bonding layer). This segmentation allows each component to be manufactured separately with precise gas passage patterns, then assembled together. The elastomeric bonding layer's compliance helps maintain alignment during assembly, ensuring unobstructed gas flow paths while allowing for manufacturing tolerances.
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 reduces particulate contamination, extends the lifetime of consumable parts, and maintains unobstructed gas passages, thereby improving the reliability and efficiency of plasma processing while accommodating thermal stresses.
Implementation Method 1
mismatch of coefficients of thermal expansion in the electrode plate and the backing plate
Implementation Method 2
A plasma is generated from the process gas in the reaction chamber between the showerhead electrode assembly and the substrate
Data Source
AI summary
A method of forming an elastomeric sheet adhesive bond between mating surfaces of an electrode and a backing member to accommodate stresses generated during temperature cycling due to mismatch in coefficients of thermal expansion. The elastomeric sheet comprises a thermally conductive silicone adhesive able to withstand a high shear strain of ≧300% in a temperature range of room temperature to 300° C. such as heat curable high molecular weight dimethyl silicone with fillers. Installation can be manually, manually with installation tooling, or with automated machinery.