Small Polishing Pad Carrier for CMP Uniformity
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Solution Overview
Problem
Chemical mechanical polishing processes often result in thickness non-uniformity across substrates, with bulk polishing leading to under-polished regions and localized non-concentric, non-uniform spots that are difficult to address with traditional polishing pads.
Innovation Solution
A chemical mechanical polishing system featuring a substrate support and a polishing pad assembly with a membrane and polishing pad portion, where the polishing pad portion has a smaller diameter than the substrate, allowing for controlled pressure and orbital motion to compensate for non-uniformities, providing precise polishing and reducing substrate non-uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a traditional large polishing pad is used for bulk polishing, then productivity is improved through faster material removal, but manufacturing precision deteriorates due to under-polished regions and thickness non-uniformity
Solution Approach 1:
The polishing process is segmented into two distinct stages: bulk polishing using a large polishing pad for rapid material removal, followed by precision polishing using a small polishing pad for uniformity correction. This segmentation allows each stage to optimize for its specific function without compromising the other.
Solution Approach 2:
The system dynamically switches between different polishing pad sizes based on the polishing stage. The large polishing pad is used initially for bulk material removal, then transitions to a small polishing pad for precision work on non-uniform regions, allowing the system to adapt its polishing characteristics to the current substrate state.
2Manufacturing precision
If excessive polishing slurry is used to address non-uniform regions, then manufacturing precision improves through better coverage, but loss of substance increases due to excessive slurry consumption
Solution Approach 1:
Instead of applying polishing slurry uniformly across the entire substrate surface, the small polishing pad concentrates the slurry application only on the specific non-uniform regions that require precision polishing. This localized approach ensures adequate coverage of problem areas while minimizing slurry consumption on already-polished regions.
3Manufacturing precision
If a small polishing pad with orbital motion is used for precision polishing, then manufacturing precision improves through compensation of non-concentric non-uniformity, but device complexity increases due to orbital motion mechanism
Solution Approach 1:
The small polishing pad is mounted on a compliant carrier that enables orbital motion through a simple eccentric rotation mechanism. This dynamic motion pattern allows the pad to naturally compensate for non-concentric non-uniformities on the substrate surface without requiring complex multi-axis positioning systems or sophisticated control algorithms.
Solution Approach 2:
The orbital motion of the small polishing pad changes the effective polishing parameters by varying the contact pressure and relative velocity across different regions of the substrate. This parameter variation allows the system to compensate for non-concentric non-uniformities through motion-induced averaging rather than through complex mechanical positioning.
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
The system achieves improved substrate uniformity and finish by allowing for controlled polishing rates and precise slurry application, reducing the need for excessive slurry usage and extending pad lifetime, while maintaining angular orientation during orbital motion.
Implementation Method 1
at least during application of a sufficient pressure to the first chamber the polishing pad portion projects through the aperture
Implementation Method 2
The polishing pad portion has a polishing surface to contact the substrate during the polishing operation
Data Source
AI summary
A chemical mechanical polishing system includes a substrate support configured to hold a substrate during a polishing operation, a polishing pad assembly include a membrane and a polishing pad portion, a polishing pad carrier, and a drive system configured to cause relative motion between the substrate support and the polishing pad carrier. The polishing pad carrier includes a casing having a cavity and an aperture connecting the cavity to an exterior of the casing. The polishing pad assembly is positioned in the casing such that the membrane divides the cavity into a first chamber and a second chamber and the aperture extends from the second chamber. The polishing pad carrier and polishing pad assembly are positioned and configured such that at least during application of a sufficient pressure to the first chamber the polishing pad portion projects through the aperture.