Multilayer CMP Polishing Pad Renewal by Laser Ablation
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Solution Overview
Problem
The performance of polishing pads in chemical mechanical planarization (CMP) processes deteriorates over time due to uneven surface conditioning, leading to polishing variation across wafers and increased costs and yield loss.
Innovation Solution
A multilayer polishing pad system with a laser unit that removes non-planar top layers to reveal fresh, planar underlying layers, maintaining consistent polishing performance throughout the pad's lifetime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If polishing pad conditioners are used to re-energize the polishing pad surface, then the polishing pad's lifetime is extended, but the polishing performance still deteriorates gradually over time leading to polishing variation across wafers
Solution Approach 1:
The polishing pad is divided into multiple layers, with a sacrificial top layer that can be selectively removed. This segmentation allows the underlying fresh layers to be exposed periodically, restoring polishing uniformity while extending the overall pad lifetime. The top layer acts as a consumable component that protects the deeper functional layers.
Solution Approach 2:
The polishing pad is pre-structured with multiple layers during manufacturing, where the top sacrificial layer is designed to be removed later to reveal fresh polishing surfaces. This preliminary preparation enables future restoration of polishing performance without replacing the entire pad.
2Duration of action of moving object
If the polishing pad surface is conditioned to extend lifetime, then the pad can be used longer, but polishing variation across wafers increases due to surface deterioration
Solution Approach 1:
The polishing pad undergoes periodic restoration by removing the deteriorated top layer to expose fresh underlying layers. This periodic action resets the polishing surface condition, maintaining process consistency and reliability throughout the extended pad lifetime.
Solution Approach 2:
The deteriorated top polishing layer is discarded through selective removal, while the underlying fresh layers are recovered and reused. This discarding and recovering process restores polishing performance without wasting the entire polishing pad structure.
3Device complexity
If a single-layer polishing pad is used, then the structure is simple, but the polishing performance deteriorates uniformly across the entire pad requiring complete replacement
Solution Approach 1:
The polishing pad is segmented into a sacrificial top layer and reusable underlying layers. This segmentation allows selective removal of only the deteriorated portion, preventing complete replacement of the pad and reducing material waste.
Solution Approach 2:
The top polishing layer is designed as a disposable sacrificial component that is periodically removed. This cheap short-living layer protects the more valuable underlying structure, which can be reused multiple times, reducing overall material waste.
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 method extends the polishing pad's lifetime and ensures consistent polishing rate and uniformity by periodically renewing the polishing surface using a laser to burn off non-uniform layers.
Implementation Method 1
a laser unit configured to produce a laser beam to remove a top polishing pad layer of the multiple layer polishing pad
Data Source
AI summary
The present disclosure describes a method and apparatus to remove consumable (e.g., sacrificial) polishing pad layers from a multilayer polishing pad. For example, the method includes measuring a thickness profile of a top polishing pad layer of a multilayer polishing pad and comparing the thickness profile to a threshold. The method, in response to the thickness profile being above the threshold, rinses the top polishing pad layer of the multilayer polishing pad and removes, after the top polishing pad layer has been rinsed, the top polishing pad layer to expose an underlying polishing pad layer of the multilayer polishing pad.