CMP Polishing Pad with Offset Grooves and Edge Exclusion
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Solution Overview
Problem
Conventional polishing pads with concentric grooves often result in non-uniform polishing and substrate scratching due to edge defects caused by groove formation, leading to a need for improved polishing pad designs that minimize these issues.
Innovation Solution
A polishing pad with a circular cross-section featuring a grooved region and an exclusion region, where the grooves are formed in a concentric, spiral, or polygonal pattern with a center of concentricity offset from the axis of rotation, and an exclusion region devoid of grooves adjacent to the circumference, preventing groove edges from reaching the pad's edge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If concentric grooves are formed on the polishing pad surface, then polishing composition delivery is improved, but edge defects occur causing substrate scratching
Solution Approach 1:
The polishing pad surface is segmented into two distinct zones: a grooved region containing concentric grooves for polishing composition delivery, and an ungrooved exclusion region near the pad edge. This segmentation allows the harmful groove edges to be isolated from the substrate contact area, eliminating scratching while preserving composition delivery in the active polishing zone.
Solution Approach 2:
Different regions of the polishing pad are given different properties: the grooved region has grooves for enhanced slurry delivery, while the exclusion region near the edge is kept ungrooved to prevent edge defects. This local differentiation allows each zone to perform its specific function optimally without causing harm.
2Manufacturing precision
If groove pattern is offset from rotation axis, then uniform polishing is improved, but groove edges still reach pad edge causing defects
Solution Approach 1:
The polishing pad is divided into a grooved region and an ungrooved exclusion region. The offset concentric grooves are contained within the grooved region, maintaining their uniformity-benefiting offset configuration, while the exclusion region prevents groove edges from reaching the pad circumference where they would cause defects.
Solution Approach 2:
The ungrooved exclusion region acts as an intermediary buffer zone between the offset concentric grooves and the pad edge. This intermediate region absorbs the potential harm of groove edges by providing a transition zone that prevents direct contact between groove edges and the substrate at the pad perimeter.
3Quantity of substance
If grooves extend to pad edge, then polishing composition access is maximized, but groove formation defects occur
Solution Approach 1:
The pad surface is segmented into a grooved region where grooves provide composition access, and an ungrooved exclusion region near the edge. This segmentation ensures that grooves do not extend to the pad edge, preventing formation defects while maintaining adequate composition access in the active polishing zone.
Solution Approach 2:
Instead of extending grooves to the maximum possible extent (excessive action), grooves are intentionally stopped before reaching the pad edge. This partial action prevents edge defects while still providing sufficient polishing composition access for effective polishing in the grooved region.
Data Source
AI summary
The invention provides a polishing pad and a method of using the polishing pad for chemically-mechanically polishing a substrate. The polishing pad comprises at least a grooved region and an exclusion region, wherein the exclusion region is adjacent to the circumference of the polishing pad, and wherein the exclusion region is devoid of grooves.