Polishing Head Membrane Rib Structure for Wrinkle-Free CMP
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Solution Overview
Problem
Existing polishing treatment devices suffer from uneven polishing, such as insufficient polishing or over-polishing, due to dynamic phenomena like the wrinkle and star mark phenomena, which have not been adequately addressed by conventional measures.
Innovation Solution
A polishing head and treatment device with an annular body, elastic body, retainer ring, and radial ribs, along with rib lock members, are designed to prevent deformation and maintain synchronized rotation, reducing the occurrence of wrinkles and star marks, and improve the substrate surface quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional polishing heads are used, then the structure is simple, but wrinkle and star mark phenomena occur causing uneven polishing
Solution Approach 1:
The polishing head is divided into multiple functional segments: a backing plate, a membrane layer, and multiple radial ribs extending from the center. This segmentation allows each component to address specific issues - the membrane prevents wrinkle formation while the radial ribs prevent star mark patterns, collectively achieving uniform polishing without excessive overall complexity
Solution Approach 2:
Different regions of the polishing head are given different structural characteristics tailored to local requirements. The membrane layer is positioned specifically to prevent wrinkle formation in the central region, while radial ribs are arranged to prevent star mark patterns at the periphery. This localized structural differentiation addresses specific polishing defects in specific areas
2Manufacturing precision
If the membrane is allowed to deform freely during rotation, then the structure is simple, but wrinkle phenomenon occurs
Solution Approach 1:
A membrane layer is introduced as a flexible thin film between the backing plate and the substrate. This membrane is specifically designed to prevent wrinkle formation during polishing while maintaining flexibility to accommodate the polishing process. The membrane acts as a protective layer that eliminates surface defects without requiring complex rigid support structures
Solution Approach 2:
The membrane serves as an intermediary element between the rigid backing plate and the substrate being polished. It mediates the mechanical stresses during polishing, preventing direct contact between the backing plate and the substrate that would cause wrinkle formation. This intermediary layer absorbs and distributes stresses uniformly
3Manufacturing precision
If radial ribs are added to prevent wrinkle, then wrinkle phenomenon is reduced, but star mark phenomenon may occur
Solution Approach 1:
The radial ribs are segmented into multiple discrete structures extending from the center to the periphery of the membrane. This segmentation allows the ribs to prevent star mark patterns by creating multiple contact points with the substrate, distributing the polishing force uniformly across the surface and preventing localized stress concentration that would cause star mark defects
4Manufacturing precision
If the retainer ring inner diameter is reduced to minimize gap, then star mark phenomenon is reduced, but difficulty in attaching and removing substrate increases
Solution Approach 1:
The retainer ring is designed with dynamic adjustability, allowing its inner diameter to be changed during operation. This enables the retainer ring to adapt to different substrate sizes and polishing conditions, maintaining an optimal gap that prevents star mark patterns while ensuring easy attachment and removal of substrates. The dynamic adjustment capability resolves the contradiction between minimizing gaps and maintaining operational ease
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 effectively prevents wrinkle and star mark phenomena, ensuring high-quality polishing treatment of multiple substrates by maintaining uniform polishing pressure and reducing surface irregularities.
Implementation Method 1
an elastic body that covers a lower end-side opening part of the annular body and holds the substrate with a backing film pasted to a front surface side of the elastic body interposed therebetween
Data Source
AI summary
Provided is a polishing head and a polishing treatment device that can cope with the wrinkle phenomenon, the star mark phenomenon and the like, further improve the SFOR or the like of the substrate surface and steadily perform a polishing treatment of a large number of substrates with high quality.A polishing head 100 includes a membrane support ring 3, a membrane 4 that covers a lower end-side opening part of the membrane support ring 3 and holds a substrate W with a backing film 5 pasted to a front surface side thereof interposed therebetween, and a retainer ring 6 shaped to accommodate the membrane support ring 3 and surround the outer circumference of the substrate W. On the back surface side of the membrane 4, a plurality of radial ribs 4a that radially extend from the vicinity of the center of the membrane 4 and a circular rib 4b that is shaped to have a size smaller than the size of the elastic body are formed, and the radial ribs 4a are formed to radially extend outward from the circular rib 4b. In a region defined by adjacent radial ribs 4a, the membrane support ring 3 and the circular rib 4b on the back surface side of the elastic body, a rib lock member 33 shaped to be in contact with the side surfaces of the adjacent radial ribs 4a, the inner circumferential surface of the membrane support ring 3 and the outer circumferential surface of the circular rib 4b is arranged.