CMP Pad Groove Segmentation for Wafer Thickness Uniformity
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Solution Overview
Problem
The non-uniform flow of slurry during chemical mechanical polishing (CMP) processes leads to variations in zone thickness across semiconductor wafers, resulting in defects and reduced yield and electrical performance of integrated circuit devices.
Innovation Solution
The use of polishing pads with geometric patterns formed by groove segments that impede radial slurry flow, increasing slurry retention time and uniformity, thereby enhancing thickness uniformity and reducing slurry consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If slurry is applied during CMP process, then polishing action is achieved, but non-uniform slurry flow causes variations in zone thickness
Solution Approach 1:
The polishing pad is segmented into multiple groove segments arranged in geometric patterns (circles, triangles, squares, hexagons, or random patterns). These segmented grooves disrupt the radial slurry flow and redistribute it uniformly across the wafer surface, eliminating the non-uniform flow that causes zone thickness variations. The segmentation transforms the continuous radial flow into a distributed uniform flow pattern.
Solution Approach 2:
The groove segments are positioned asymmetrically relative to the wafer center, with grooves located at offset distances from the center. This asymmetric arrangement prevents symmetric radial flow patterns and promotes uniform slurry distribution across different zones of the wafer, thereby improving thickness uniformity while maintaining effective polishing action.
2Manufacturing precision
If geometric patterns with groove segments are added to polishing pad, then slurry retention time increases and uniformity improves, but device complexity increases
Solution Approach 1:
The polishing pad incorporates groove segments that create a porous-like structure with channels and cavities. These grooves retain slurry within the pad structure, increasing slurry retention time and promoting uniform distribution. The porous structure achieves improved thickness uniformity without requiring complex external systems, as the grooves themselves perform the slurry management function.
Solution Approach 2:
The groove segments extend into the depth dimension of the polishing pad, creating a three-dimensional geometric pattern rather than a simple surface feature. This dimensional addition allows the grooves to impede radial flow and retain slurry effectively, improving thickness uniformity while maintaining a relatively simple overall pad structure that can be manufactured using standard techniques.
3Manufacturing precision
If radial slurry flow is allowed, then polishing action occurs, but slurry consumption increases and uniformity decreases
Solution Approach 1:
The groove segments act as intermediary structures between the slurry supply and the wafer surface. They intercept the radially flowing slurry, redistribute it uniformly across the polishing interface, and extend slurry retention time. This intermediary action reduces slurry consumption by ensuring more efficient utilization of the applied slurry, while simultaneously improving flow uniformity and thickness consistency.
Data Source
AI summary
Some implementations described herein relate to dispensing a slurry onto a polishing pad for a chemical-mechanical planarization (CMP) process. These implementations also involve rotating the polishing pad while the slurry is dispensed onto the polishing pad. Rotation of the polishing pad results in a traversal of the slurry radially outward toward a polishing pad outer edge of the polishing pad. The polishing pad includes a plurality of groove segments and a geometric patterns formed by the plurality of the groove segments impede the flow of the slurry to the polishing pad outer edge.