Retainer Ring Threaded Fastening for CMP Polishing Head
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Solution Overview
Problem
The existing CMP apparatus requires frequent replacement of the retainer ring, which is time-consuming and results in increased downtime, and the fastening process can cause deformation of the retainer ring, affecting the polishing rate of the wafer's peripheral portion.
Innovation Solution
A polishing head design featuring a retainer ring secured to a drive ring using a first and second screw thread that extends circumferentially, allowing for easy mounting and removal without disassembling the polishing head, and a locking structure to prevent loosening during operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the retainer ring is fastened by multiple screws to secure it to the drive ring, then the retainer ring is firmly fixed, but the retainer ring may deform due to stress concentration and replacement requires disassembly of the polishing head
Solution Approach 1:
The fastening system is segmented into a drive ring with external threads and a retainer ring with internal threads. This segmentation allows the retainer ring to be independently attached and detached from the drive ring by simple screwing and unscrewing motions, eliminating the need to disassemble the entire polishing head for replacement.
Solution Approach 2:
The fastening mechanism (screw threads) is extracted as a separate functional element from the main polishing head structure. The drive ring serves as a dedicated fastening component that can be quickly engaged or disengaged from the retainer ring, enabling rapid replacement without affecting other parts of the polishing head.
2Reliability
If multiple screws are used to fasten the retainer ring, then the retainer ring is securely fixed, but stress distribution becomes uneven causing deformation
Solution Approach 1:
Instead of using multiple discrete screws that create localized stress points, the fastening system uses continuous screw threads distributed uniformly around the circumference of the drive ring and retainer ring. This continuous distribution of fastening elements ensures even stress distribution across the entire retainer ring, preventing localized deformation while maintaining secure fixation.
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
Enables quick and secure replacement of the retainer ring without deformation, reducing downtime and ensuring consistent polishing performance by maintaining uniform stress and fastening force across the retainer ring.
Implementation Method 1
Since the retainer ring 301 is in sliding contact with the polishing pad during polishing of a wafer W
Implementation Method 2
a first screw thread is formed on the drive ring, a second screw thread, which engages with the first screw thread, is formed on the retainer ring
Data Source
AI summary
A polishing apparatus which can allow easy replacement of a retainer ring and can allow the retainer ring to be secured to a drive ring without causing deformation of the retainer ring is disclosed. The polishing head includes a head body having a substrate contact surface, a drive ring coupled to the head body, and a retainer ring surrounding the substrate contact surface and coupled to the drive ring. A first screw thread is formed on the drive ring, a second screw thread, which engages with the first screw thread, is formed on the retainer ring. The second screw thread extends in a circumferential direction of the retainer ring.