Two-Zone CMP Pad Layout for Silicon Carbide 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 simultaneously achieving precise dimensions and surface finishes due to the material's hardness and brittleness, along with issues in combining effective oxidizing and abrasive properties in traditional slurry compositions, leading to contamination and clogging.
Innovation Solution
A polishing system with a platen and polishing pad divided into zones, each dedicated to specific processes like oxidation and oxide removal, using separate materials and controlled actuators to activate these processes in a pulsed manner, reducing contamination and optimizing process conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional slurry compositions combine oxidizing and abrasive properties, then polishing effectiveness is improved, but contamination and clogging occur
Solution Approach 1:
The polishing pad is divided into multiple zones, with each zone dedicated to a specific function (oxidation, oxide removal, or both). This spatial segmentation allows oxidizing materials and abrasive materials to be applied separately in different zones, preventing contamination and clogging while maintaining polishing effectiveness. The separator physically divides the polishing pad surface to enable independent material application in each zone.
Solution Approach 2:
Different zones of the polishing pad are assigned different functional properties: some zones are optimized for oxidation with oxidizing materials, while other zones are optimized for oxide removal with abrasive materials. This local differentiation allows each zone to perform its specific function optimally without interference from other materials, resolving the contradiction between effectiveness and contamination.
2Manufacturing precision
If polishing pressure and speed are increased to achieve precise dimensions, then manufacturing precision is improved, but heat generation and crack formation increase
Solution Approach 1:
The polishing process is segmented into distinct functional zones: oxidation zones that prepare the surface with minimal mechanical stress, and oxide removal zones that perform material removal. This segmentation allows the workpiece to pass through different process stages at optimized parameters, achieving precision without excessive heat and stress concentration.
Solution Approach 2:
The oxidation zones perform preliminary surface preparation by forming oxide layers before the workpiece reaches the oxide removal zones. This preliminary chemical action softens the surface and prepares it for controlled mechanical removal, enabling precise dimensional control with reduced risk of cracking compared to direct mechanical polishing.
3Productivity
If oxidation and oxide removal are performed simultaneously, then process efficiency is improved, but material contamination increases
Solution Approach 1:
The polishing pad is segmented into multiple zones that can simultaneously perform oxidation and oxide removal functions. The separator divides the pad into distinct regions where oxidizing materials and abrasive materials are applied separately, allowing both processes to occur concurrently without cross-contamination. Each zone operates independently, maintaining process efficiency while preventing material mixing.
Solution Approach 2:
The separator acts as an intermediary structure that physically separates the application regions of different materials. It enables simultaneous delivery of oxidizing materials to oxidation zones and abrasive materials to oxide removal zones, facilitating concurrent processes while preventing contamination between material streams.
4Duration of action of stationary object
If polishing pad material is made more durable to extend lifespan, then device durability is improved, but polishing performance may be compromised
Solution Approach 1:
The polishing pad is segmented into multiple zones with different material compositions and properties optimized for specific functions. Oxidation zones use materials suited for chemical reactions, while oxide removal zones use materials optimized for abrasive action. This segmentation allows each zone to perform its function effectively, maintaining high surface finish quality while the overall pad structure remains durable and long-lasting.
Solution Approach 2:
Different regions of the polishing pad are given different local properties: oxidation zones have materials optimized for chemical oxidation, while oxide removal zones have materials optimized for mechanical abrasion. This local quality differentiation ensures that each zone delivers optimal performance for its specific function, maintaining overall polishing precision while extending pad lifespan through specialized material selection in each region.
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 reduces tool wear, extends polishing pad lifespan, enhances process efficiency, and minimizes contamination, improving the quality and speed of silicon carbide wafer polishing by separating oxidation and oxide removal processes.
Implementation Method 1
activating an oxidation process on the semiconductor workpiece
Implementation Method 2
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.