Polishing Pad Laminated Structure for CMP Sensor Alignment
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Solution Overview
Problem
The existing chemical mechanical polishing (CMP) processes for semiconductor devices face challenges in accurately aligning the through-hole of the polishing pad with the sensor head in the polishing table, leading to decreased film-thickness measuring accuracy and increased operation time due to the small size and complexity of the through-hole.
Innovation Solution
A polishing-pad laminated structure with a release sheet and a positioning instrument featuring a second positioning protrusion with a cross-sectional shape matching the through-hole, allowing for precise alignment and easy attachment of the polishing pad to the polishing table, utilizing a first positioning protrusion and support structure for alignment assistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the through-hole of the polishing pad is made small to improve measurement precision, then the film-thickness measuring accuracy is improved, but the alignment difficulty increases and operation time increases
Solution Approach 1:
The polishing pad is divided into multiple layers (first polishing pad layer, second polishing pad layer, third polishing pad layer) with through-holes at different positions. The first layer has a through-hole aligned with the sensor head for measurement, while the second and third layers have offset through-holes that serve as alignment marks, separating the measurement function from the alignment function.
Solution Approach 2:
A positioning mark is introduced as an intermediary element between the through-hole and the sensor head. The positioning mark (cross-shaped or ring-shaped) provides a visual reference that facilitates alignment without requiring direct alignment of the small through-hole with the sensor head, thus easing the operation while maintaining measurement precision.
2Measurement precision
If the through-hole of the polishing pad is made small to improve measurement precision, then the film-thickness measuring accuracy is improved, but the operation rate decreases
Solution Approach 1:
The polishing pad is divided into multiple layers with through-holes at different positions. The first layer's through-hole is small and aligned with the sensor head for precise measurement, while the second and third layers have larger offset through-holes that serve as alignment marks, enabling faster alignment without compromising measurement accuracy.
Solution Approach 2:
The positioning mark serves as an intermediary that speeds up the alignment process. Operators can align the polishing pad by matching the positioning mark with its corresponding mark on the polishing table, rather than attempting to align the small through-hole directly with the sensor head, thus improving operation rate while maintaining measurement precision.
3Ease of operation
If a positioning structure is added to facilitate alignment, then the ease of operation is improved, but the device complexity increases
Solution Approach 1:
The positioning function is segmented into simple visual markers (positioning marks on the polishing pad and corresponding marks on the polishing table) rather than using a complex mechanical positioning structure. This maintains ease of operation while minimizing added complexity.
Solution Approach 2:
The positioning mark on the polishing pad is a simplified copy or representation of the alignment feature on the polishing table. Instead of replicating the complex sensor head positioning mechanism, a simple visual copy (cross-shaped or ring-shaped mark) is used to guide alignment, reducing device complexity while improving ease of operation.
Data Source
AI summary
A polishing-pad laminated structure which allows for easy alignment of a through-hole of a polishing pad with a sensor head installed in a polishing table is disclosed. The polishing-pad laminated structure includes a polishing pad and a release sheet. The polishing pad has a through-hole located at a position corresponding to a position of a sensor head disposed in the polishing table. The release sheet covers an adhesive surface of the polishing pad. The release sheet is divided into at least a first release sheet and a second release sheet. The first release sheet has a surface area smaller than a surface area of the second release sheet.