Polishing Head Retainer End Surface Geometry for Substrate Corner Protection
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Solution Overview
Problem
Conventional CMP apparatuses face challenges in processing large and heavy substrates, such as Copper Clad Laminate and Printed Circuit Board substrates, due to potential substrate damage and deformation from collisions with retainers during polishing, as existing techniques are not standardized for these non-circular substrates.
Innovation Solution
A polishing head with a retainer design featuring an end region that increases in distance from the substrate holding surface towards its end portion, positioned adjacent to the substrate's corner, reduces the risk of collision damage by avoiding direct contact between the substrate's corner and the retainer, and includes a curved or chamfered edge to prevent substrate breakage and jumping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional retainer design is used to prevent substrate from jumping out during polishing, then substrate containment is improved, but substrate damage risk increases due to collision with the retainer
Solution Approach 1:
The retainer's end surface is designed to be curved rather than flat, creating a gradual slope that guides the substrate corner away from the retainer during rotation. This curved geometry prevents direct collision while maintaining containment, resolving the contradiction between preventing substrate ejection and avoiding damage.
Solution Approach 2:
The retainer features asymmetric geometry with the end surface positioned at a specific distance from the substrate holding surface, creating an asymmetric gap that accommodates the substrate corner without direct contact. This asymmetric design allows the substrate to rotate freely without colliding with the retainer while still preventing jumping out.
2Productivity
If the substrate dimension is increased to improve production efficiency, then productivity is improved, but substrate deformation increases due to weight and warp
Solution Approach 1:
The retainer is positioned to provide counterbalancing support near the substrate corner, acting as a counterweight that helps maintain substrate flatness during rotation. This counterbalancing effect compensates for the weight-induced warp in large substrates, enabling stable processing of bigger substrates for improved productivity.
3Reliability
If the retainer is positioned closer to the substrate to prevent jumping out, then substrate containment is improved, but collision damage increases
Solution Approach 1:
The solution moves the containment mechanism from a horizontal proximity arrangement to a vertical dimensional arrangement. The end surface of the retainer is positioned at a specific vertical distance from the substrate holding surface, creating a three-dimensional containment space that prevents jumping out without requiring horizontal proximity that would cause collision.
Data Source
AI summary
To reduce a risk generated at a time of collision of a substrate with a retainer. According to one embodiment, a head for holding a polygonal substrate as a polishing object of a polishing apparatus is provided. The head includes a substrate holding surface configured to hold a substrate and a retainer positioned outside the substrate holding surface. The retainer has an end region. The end region is arranged adjacent to a corner portion of the substrate held onto the head. The end region has an end surface on a side of the substrate holding surface. The end surface is configured to increase in distance from the substrate holding surface with approaching an end portion in a longitudinal direction of the retainer.