Roughened Lip Elastic Membrane for CMP Substrate Holding
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Solution Overview
Problem
The existing substrate holding apparatuses for CMP polishing face challenges in maintaining uniform pressure distribution across the wafer due to uneven deformation of the elastic membrane, leading to inconsistent polishing results and increased labor in securing the membrane.
Innovation Solution
The elastic membrane is designed with a roughened edge-circumferential-wall lip portion and inner-circumferential-wall lip portion to reduce contact area with the head body and mounting members, allowing for easier and more secure attachment while minimizing deformation variations, and features projections and recesses for guided alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the elastic membrane is made of highly adhesive material to ensure flexibility, then the membrane can be securely attached to the head body, but the membrane adheres too strongly to the head body and mounting members during installation, causing distortion and making installation difficult
Solution Approach 1:
The elastic membrane is divided into functionally distinct regions: a smooth contact portion for uniform substrate pressing and a roughened edge-circumferential-wall lip portion for controlled mounting. This segmentation allows different surface properties in different areas, resolving the contradiction between adhesive strength and ease of installation.
Solution Approach 2:
The surface quality of the elastic membrane is made non-uniform: the contact portion maintains smoothness for its pressing function, while the edge-circumferential-wall lip portion is roughened to reduce adhesion during mounting. This local differentiation of surface properties enables the membrane to exhibit both strong adhesion where needed and easy installation where required.
2Manufacturing precision
If the worker manually adjusts the elastic membrane to eliminate deformation variation, then uniform polishing can be achieved, but the installation time and labor burden increase significantly
Solution Approach 1:
The roughened surface is pre-formed on the edge-circumferential-wall lip portion during membrane manufacturing. This preliminary preparation of the mounting surface ensures that during installation, the membrane naturally resists adhesion to the head body and mounting members, eliminating the need for manual adjustment to prevent distortion and significantly reducing installation time.
3Ease of repair
If the elastic membrane is made detachable for maintenance and replacement, then the apparatus can be maintained regularly, but the membrane may distort during removal and reattachment processes
Solution Approach 1:
The elastic membrane is designed as a detachable component with a specific mounting structure involving the edge-circumferential-wall lip portion that interfaces with the head body and mounting members. This segmentation enables easy removal and reattachment while the roughened lip portion ensures that during each attachment cycle, the membrane maintains its structural integrity without distortion.
4Stress or pressure
If fluid pressure is supplied uniformly to the pressure chamber, then uniform pressing force is applied to the substrate, but variations in membrane deformation cause non-uniform pressure distribution
Solution Approach 1:
The elastic membrane features a roughened edge-circumferential-wall lip portion that locally modifies adhesion characteristics during mounting. This local surface modification ensures uniform deformation of the membrane when pressurized, which in turn enables uniform pressing force distribution across the substrate during polishing operations.
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 design enables smooth and easy securing of the elastic membrane, ensuring uniform pressure distribution and reducing the labor required for installation, thereby enhancing the consistency and efficiency of the polishing process.
Implementation Method 1
the elastic membrane is typically made of materials, such as rubber, which are not only flexible but also highly adhesive. Therefore, when a worker secures the elastic membrane to the head body through the mounting members, a portion of the elastic membrane may be in close contact with the head body and/or the mounting member
Implementation Method 2
the substrate holding apparatus has a pressure chamber defined by an elastic membrane at a lower part thereof. This pressure chamber is supplied with a fluid, such as air, to press the wafer through the elastic membrane with a fluid pressure
Data Source
AI summary
An elastic membrane capable of being easily secured to a head body of a substrate holding apparatus while inhibiting variation of a degree of deformation of the elastic membrane in a circumferential direction is disclosed. The elastic membrane according to the present invention is used in the substrate holding apparatus. The elastic membrane includes: a contact portion to be brought into contact with a substrate for pressing the substrate against a polishing pad; and an edge circumferential wall extending from a peripheral edge of the contact portion. The edge circumferential wall includes an edge-circumferential-wall lip portion sandwiched between a head body of the substrate holding apparatus and an edge mounting member for securing the edge circumferential wall to the head body. The edge-circumferential-wall lip portion has at least a part of a surface thereof roughened.