Hybrid Polishing Pad Conditioning for Silicon Carbide CMP
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Solution Overview
Problem
Polishing processes for silicon carbide semiconductor wafers face challenges due to the material's high hardness and brittleness, leading to excessive tool wear, heat generation, and difficulty in achieving precise dimensions and surface finishes, with single wafer CMP processes being time-consuming and inefficient.
Innovation Solution
Implementing a hybrid pad conditioning method combining in-situ and ex-situ processes, where the pad conditioner contacts the polishing pad during and outside the polishing operation, with in-situ conditioning adjusted based on process conditions, and using a system with a controller to manage pad conditioner contact and material delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If single wafer CMP process is used for polishing silicon carbide wafers, then manufacturing precision can be achieved, but productivity is low and the process is time-consuming
Solution Approach 1:
The polishing process is segmented into multiple stages: coarse polishing, fine polishing, and finishing polishing. Each stage uses different polishing pads and parameters to achieve progressive refinement. This segmentation allows the system to maintain high precision while improving throughput by performing multiple polishing operations in sequence without requiring complete process reconfiguration.
Solution Approach 2:
The system dynamically adjusts polishing parameters including pressure, rotation speed, and slurry flow rates during different stages of the polishing process. The controller adapts these parameters in real-time based on process conditions, enabling optimized performance at each polishing stage while maintaining overall process efficiency and productivity.
2Productivity
If polishing pressure is increased to improve material removal rate, then productivity improves, but heat generation increases causing tool wear
Solution Approach 1:
The system employs periodic intermittent polishing where the polishing head is raised and lowered between polishing cycles. During non-polishing intervals, cooling fluid is applied to the polishing pad and tool head to dissipate heat. This periodic action allows high material removal rates during polishing phases while managing thermal accumulation through cooling phases between operations.
Solution Approach 2:
Cooling fluid acts as an intermediary substance that transfers heat away from the polishing interface. The cooling fluid is delivered through the polishing system to directly cool the polishing pad and workpiece contact areas, preventing excessive heat generation during high-pressure polishing operations while maintaining productive material removal rates.
3Manufacturing precision
If in-situ pad conditioning is performed continuously during polishing, then manufacturing precision is maintained, but device complexity increases
Solution Approach 1:
The pad conditioning function is merged with the polishing operation itself. The conditioner is integrated into the polishing head assembly, allowing it to perform conditioning actions during the polishing process without requiring separate conditioning equipment. This merging maintains surface finish quality while reducing overall system complexity by combining multiple functions into a single integrated unit.
Solution Approach 2:
The pad conditioner is designed to automatically adjust and perform conditioning based on detected pad conditions. The system monitors polishing quality parameters and self-regulates the conditioning process, eliminating the need for complex external control systems while maintaining consistent manufacturing precision through autonomous pad maintenance.
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
Improves throughput and material removal rates while reducing slurry consumption, enhancing the efficiency and effectiveness of silicon carbide wafer polishing.
Implementation Method 1
The pad conditioner is then caused to contact the polishing pad while a cleaning agent is applied to the polishing pad
Data Source
AI summary
A method for conditioning a polishing pad of a polishing system is provided. The method comprises performing an in-situ pad conditioning process and an ex-situ pad conditioning process outside of a polishing operation. The in-situ pad conditioning process comprises causing a pad conditioner to contact the polishing pad during the polishing operation. The ex-situ pad conditioning process comprises causing the pad conditioner to contact the polishing pad while a cleaning agent is applied to the polishing pad.