Multi-Zone CMP Pad Layout for Stable SiC Wafer Polishing
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Solution Overview
Problem
Polishing processes for silicon carbide semiconductor wafers face challenges such as excessive tool wear, heat generation, crack formation, and difficulty in combining effective oxidizing and oxide removal processes due to slurry instability and abrasive particle control, leading to contamination and reduced efficiency.
Innovation Solution
A polishing system with a platen and polishing pad divided into multiple zones, each dedicated to specific processes like oxidation and oxide removal, using actuatable materials activated by external stimuli to maintain separation and optimize conditions for each process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single polishing pad is used for both oxidation and oxide removal processes, then device complexity is reduced, but manufacturing precision and process reliability deteriorate due to slurry instability and contamination
Solution Approach 1:
The polishing pad is divided into multiple zones (first zone and second zone) where each zone performs a different function - one zone for oxidation process and another zone for oxide removal process. This segmentation allows each zone to maintain optimized slurry conditions and abrasive particle control independently, resolving the slurry instability and contamination issues that arise from using a single pad for both processes.
Solution Approach 2:
Different regions of the polishing pad are provided with different local properties - the first zone has properties optimized for oxidation (e.g., specific porosity, chemical composition) while the second zone has properties optimized for oxide removal (e.g., different abrasive distribution, mechanical properties). This local quality differentiation enables each zone to perform its specific function effectively without interfering with the other process.
2Productivity
If polishing pad is continuously used without separation of processes, then productivity is maintained, but tool wear increases and polishing pad lifespan is reduced
Solution Approach 1:
By segmenting the polishing pad into functionally independent zones, each zone experiences different wear patterns and can be optimized for its specific process. The oxidation zone and oxide removal zone can be maintained at different wear levels simultaneously, allowing the overall pad to remain functional longer than a single-zone pad that must be replaced when any one area degrades.
Solution Approach 2:
The multi-zone design allows selective replacement or regeneration of only the worn zones while preserving functional zones. This extends the overall polishing pad lifespan by enabling partial recovery and selective maintenance rather than requiring complete pad replacement when any single area degrades.
3Loss of time
If oxidation and oxide removal processes are performed simultaneously on the same surface, then processing time is reduced, but process control becomes difficult due to conflicting material requirements
Solution Approach 1:
Instead of performing both processes sequentially in time (one after another), the invention transitions to spatial parallelism by executing both oxidation and oxide removal processes simultaneously at different spatial locations (different zones) on the polishing pad. This dimensional change from time-based to space-based process separation maintains high productivity while enabling independent control of each process's parameters and materials.
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
Reduces contamination, extends polishing pad lifespan, improves process efficiency, and enhances system stability by optimizing process conditions, minimizing clogging and cleaning needs.
Implementation Method 1
chemical mechanical polishing
Implementation Method 2
chemical mechanical polishing
Implementation Method 3
activating an oxidation process on the semiconductor workpiece
Implementation Method 4
activating an oxide removal process on the semiconductor workpiece
Data Source
AI summary
Systems and methods for polishing semiconductor workpieces are provided. In one example, the polishing system includes a platen operable to rotate about an axis. The polishing system further includes a polishing pad on the platen. The polishing system further includes a workpiece carrier operable to bring a semiconductor workpiece into contact with the polishing pad. The polishing pad includes a first zone and a second zone.