Retaining Ring Inserts for CMP Force Dissipation
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Solution Overview
Problem
Existing retaining rings used in chemical mechanical polishing introduce undesirable materials and deformations, contaminating the polishing environment and damaging semiconductor wafers, especially when polishing conductive and non-conductive materials.
Innovation Solution
A one-piece retaining ring with a generally annular body and inserts made of materials that deform less than the ring itself, positioned to avoid contact with chemicals and using convex or concave side walls for force dissipation, allowing secure attachment to a carrier head without introducing contaminants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a retaining ring is made of metal to provide strength and rigidity, then the structural strength is improved, but contamination with mobile ions occurs during polishing of non-conductive materials
Solution Approach 1:
The retaining ring material is changed from metal to plastic, fundamentally altering the chemical properties to be non-reactive with polishing chemicals. This parameter change eliminates mobile ion contamination while maintaining sufficient mechanical strength through proper plastic material selection
Solution Approach 2:
The retaining ring uses composite construction with a plastic body and metal inserts. The plastic provides chemical inertness while the metal inserts provide localized reinforcement at fastener locations, combining the advantages of both material types to resolve the contradiction between strength and contamination
2Object-affected harmful factors
If a retaining ring is made of plastic to avoid chemical reactivity, then contamination is reduced, but the heat stability and friction resistance are insufficient compared to metal
Solution Approach 1:
The retaining ring employs a composite structure where a thermally stable plastic body is reinforced with metal inserts at critical locations. This composite approach allows the plastic to provide chemical inertness while the metal inserts compensate for thermal and frictional limitations
Solution Approach 2:
Metal reinforcement is applied locally only at fastener locations and high-stress areas rather than the entire retaining ring. This localized approach provides thermal and friction resistance where needed while maintaining chemical inertness throughout the entire structure
3Strength
If fasteners are used to attach the retaining ring to the carrier head, then secure attachment is achieved, but deformation occurs at fastener locations during polishing
Solution Approach 1:
Metal inserts are integrated into the plastic retaining ring at fastener locations to provide local reinforcement. This composite structure allows fasteners to be attached without causing deformation, as the metal inserts bear the mechanical stress and maintain dimensional stability
Solution Approach 2:
The metal inserts are pre-installed into the plastic retaining ring body before final assembly, providing pre-established reinforcement at fastener locations. This beforehand strengthening prevents deformation during the polishing process by distributing mechanical stresses away from the plastic material
Data Source
AI summary
An improved retaining ring used for chemical mechanical polishing of substrates, such as semiconductor wafers, to hold a substrate in place during the polishing process. The retaining rings are configured with inserts through which fasteners are positioned to securely affix the retaining ring to the polishing head. The inserts assist in dissipating the force of the fasteners, thereby allowing a more uniform polishing surface. The opening through which the fastener is positioned may be configured with concave or convex side walls to assist in dissipating the force of the fasteners during installation of the retaining ring or the polishing process.