CMP Pad Thermal Zoning for In-Situ Edge Asymmetry Correction
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Solution Overview
Problem
Chemical mechanical polishing (CMP) processes often result in edge asymmetry and non-uniform polishing rates across the substrate, leading to irregular substrate thickness and low throughput in correcting these issues, as existing methods require post-polishing touch-up tools for uniformity.
Innovation Solution
A CMP apparatus with a thermal control system that generates zones of different temperatures on the polishing pad, allowing for in-situ correction of edge asymmetry by synchronizing carrier head motion with temperature variations to adjust polishing rates across the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional CMP processes are used with uniform polishing conditions, then the polishing process is simple and fast, but edge asymmetry and non-uniform polishing profiles occur due to varying removal rates across the substrate
Solution Approach 1:
The patent applies local quality by creating distinct temperature zones (first zone with first temperature, second zone with second temperature) on the polishing pad to provide different polishing rates in different regions. This resolves the contradiction by introducing spatial variation in temperature to achieve uniform polishing across the substrate edge, accepting increased system complexity for improved manufacturing precision.
Solution Approach 2:
The patent implements dynamics by dynamically adjusting the temperatures of different zones on the polishing pad during the polishing process. The carrier head is laterally oscillated and rotated in coordination with the temperature adjustments, creating time-varying conditions that compensate for edge asymmetry and achieve uniform polishing profiles.
2Manufacturing precision
If temperature zones are created on the polishing pad to correct edge asymmetry, then polishing uniformity improves, but energy consumption and system complexity increase
Solution Approach 1:
The patent applies periodic action by laterally oscillating the carrier head back and forth while rotating it, creating periodic contact between different edge portions of the substrate and different temperature zones on the polishing pad. This periodic motion, synchronized with temperature adjustments, distributes thermal energy more efficiently and achieves edge symmetry correction.
Solution Approach 2:
The patent implements preliminary action by pre-heating or pre-cooling specific zones on the polishing pad before the substrate edge contacts them. The carrier head positioning is coordinated so that thicker edge portions contact warmer zones (increased removal rate) and thinner edge portions contact cooler zones (decreased removal rate) in advance of the actual polishing need.
3Manufacturing precision
If the carrier head is laterally oscillated and rotated to synchronize with temperature zones, then within-wafer uniformity improves, but the polishing process time increases
Solution Approach 1:
The patent applies continuity of useful action by maintaining continuous relative motion between the carrier head and polishing pad through combined lateral oscillation and rotation. This continuous multi-directional motion ensures that all portions of the substrate edge receive appropriate polishing treatment throughout the polishing cycle, achieving within-wafer uniformity without significant time penalty.
Solution Approach 2:
The patent introduces another dimension by adding lateral oscillation motion in addition to the standard rotation. This transforms the polishing action from simple rotational contact to a two-dimensional scanning motion, allowing the carrier head to systematically access different temperature zones and achieve comprehensive edge correction.
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
This approach improves wafer-to-wafer uniformity and repeatability by dynamically controlling polishing rates, enabling real-time correction of edge asymmetry during the CMP process, thus enhancing the polishing profile and reducing the need for post-processing touch-ups.
Implementation Method 1
a thermal control system including a plurality of independently controllable heaters and/or coolers to independently control temperatures of a plurality of zones on the polishing pad
Implementation Method 2
a thermal control system including a plurality of independently controllable heaters and/or coolers to independently control temperatures of a plurality of zones on the polishing pad
Implementation Method 3
The thermal control system may include a nozzle to spray a medium onto the zone to adjust the temperature of the zone
Data Source
AI summary
A chemical mechanical polishing apparatus includes a platen to hold a polishing pad, a carrier laterally movable by an actuator across the polishing pad to hold a substrate against a polishing surface of the polishing pad during a polishing process, a thermal control system including a plurality of independently controllable heaters and coolers to independently control temperatures of a plurality of zones on the polishing pad, and a controller configured to cause the thermal control system to generate a first zone having a first temperature and a second zone having a different second temperature on the polishing pad.