Elastic Membrane Reinforcement for Uniform Pressure
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Solution Overview
Problem
Conventional elastic membranes in substrate holding apparatuses for semiconductor wafer polishing suffer from non-uniform deformation, leading to contact with retainer rings and resulting in pressure losses and surface irregularities during polishing, which can cause insufficient or overpolishing.
Innovation Solution
The elastic membrane is reinforced with a rigid member across its contact portion to uniformly reduce deformation from the center to the periphery, preventing contact with retainer rings and ensuring uniform pressure distribution, using thread-like or fabric reinforcing materials arranged in specific patterns to allow perpendicular deformation while minimizing longitudinal elongation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the elastic membrane is made flexible to efficiently transmit fluid pressure, then the pressure transmission efficiency is improved, but the membrane deforms excessively along the contact surface causing contact with the retainer ring and pressure loss
Solution Approach 1:
The patent applies local quality by differentiating the mechanical properties of the elastic membrane into two distinct regions: a contact portion with high flexibility for efficient pressure transmission, and peripheral wall portions with high rigidity to prevent excessive deformation. This spatial variation in material properties resolves the contradiction by allowing each region to perform its specific function optimally.
Solution Approach 2:
The elastic membrane is constructed as a composite structure combining flexible material (rubber or silicone rubber) in the contact portion with rigid material (metal or resin) in the peripheral wall portions. This composite construction enables the membrane to simultaneously achieve high pressure transmission efficiency through the flexible region while preventing retainer ring contact through the rigid peripheral regions.
2Reliability
If the elastic membrane is reinforced to reduce deformation along the contact surface, then contact with the retainer ring is prevented, but the membrane may develop creases or loosening if reinforcement is not uniform
Solution Approach 1:
The patent segments the elastic membrane into distinct functional regions: a contact portion for pressure transmission and peripheral wall portions for structural support. The reinforcement is applied selectively to the peripheral wall portions rather than uniformly across the entire membrane, allowing controlled deformation in the contact portion while preventing retainer ring contact through the reinforced peripheral regions.
Solution Approach 2:
The reinforcement is applied locally to the peripheral wall portions with high rigidity material, while the contact portion maintains high flexibility. This non-uniform reinforcement strategy prevents creases and loosening by concentrating structural support where needed (peripheral regions) while preserving the deformation capability where required (contact portion).
3Reliability
If the peripheral wall portions are made rigid to prevent contact with the retainer ring, then pressure loss is prevented, but the overall membrane flexibility is reduced
Solution Approach 1:
The membrane is segmented into two functional zones with different mechanical properties: the contact portion maintains high flexibility for adaptive pressure transmission, while the peripheral wall portions have high rigidity to prevent retainer ring contact. This segmentation allows the membrane to simultaneously achieve pressure transmission stability and maintain necessary flexibility.
Solution Approach 2:
The membrane uses composite materials combining flexible rubber or silicone rubber in the contact portion with rigid metal or resin in the peripheral wall portions. This composite construction enables the membrane to exhibit both flexible behavior where needed for pressure transmission and rigid behavior where needed to prevent contact with the retainer ring.
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 solution prevents pressure losses and surface irregularities by maintaining uniform contact and pressure across the substrate, ensuring consistent polishing performance and preventing creases or loosening of the contact surface.
Implementation Method 1
A flexible material, such as a rubber, is generally used for the elastic membrane in order to use the flexibility to efficiently transmit the fluid pressures of the pressure chambers
Implementation Method 2
substantially the entire area of the contact portion is reinforced with a reinforcing member having a higher rigidity than the elastic membrane
Implementation Method 3
a frictional force is generated between the retainer ring and the peripheral end of the elastic membrane due to interference between them
Data Source
AI summary
An elastic member for use in a substrate holding apparatus includes an elastic member and a first reinforcing member. The first reinforcing member has a higher rigidity than the elastic membrane and reinforces substantially an entire area of the contact portion of the elastic membrane. The contact portion of the elastic member has a contact portion for contact with the substrate. The first peripheral wall portion of the elastic membrane is coupled to a peripheral end of the contact portion and extends upwardly. The second peripheral wall portion of the elastic member defines a first chamber on an outer side thereof and a second chamber on an inner side thereof. The first reinforcing member is embedded in substantially the entire area of the contact portion of the elastic membrane.