Multi-Directional Polishing Pad Surface Property Measurement
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Solution Overview
Problem
There is a need for a more accurate method to measure and judge the surface properties of polishing pads used in semiconductor wafer polishing, as existing methods are not sufficient for optimizing dressing conditions and extending the life of dressers while reducing consumables.
Innovation Solution
A surface property measuring apparatus that irradiates the polishing pad with light from multiple directions and receives reflected light, using a rotating mechanism and data processing to determine intensity distributions and wavelength composition ratios, which indicate the pad's surface properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional single-direction light measurement is used, then device complexity is low, but measurement precision is insufficient for optimizing dressing conditions
Solution Approach 1:
The light-emitting structure is divided into multiple light-emitting units arranged in different directions, and the light-receiving structure is divided into multiple light-receiving units. Each unit measures surface properties from its specific direction, enabling comprehensive multi-directional measurement while keeping individual units relatively simple in structure.
Solution Approach 2:
The measurement system transitions from single-direction (one-dimensional) light emission and reception to multi-directional (three-dimensional) spatial arrangement. Light-emitting units are positioned at different angular positions around the polishing pad, and light-receiving units are correspondingly arranged to capture reflected light from multiple directions, adding spatial dimensionality to the measurement capability.
2Measurement precision
If multi-directional light measurement is implemented, then surface property measurement accuracy improves, but device complexity increases
Solution Approach 1:
Multiple light-emitting units and multiple light-receiving units are merged into a single integrated measuring head assembly. The light-emitting units and light-receiving units are positioned in fixed spatial relationships within the assembly, allowing the entire multi-directional measurement system to be treated as one unified device rather than separate components.
Solution Approach 2:
The measuring head assembly is designed to rotate around the polishing pad, dynamically changing the irradiating direction during measurement. This rotational capability allows a single physical assembly to access multiple measurement angles and directions, reducing the need for multiple static measurement stations while maintaining comprehensive measurement coverage.
3Reliability
If excessive dressing is performed to ensure polishing quality, then polishing performance is maintained, but dresser life is reduced and consumables are wasted
Solution Approach 1:
The multi-directional light measurement system provides comprehensive feedback on the actual surface properties of the polishing pad, including uniformity and directional characteristics. This detailed feedback enables precise determination of when dressing is actually needed, allowing the system to avoid unnecessary dressing operations while maintaining polishing quality, thus extending dresser life and reducing consumable waste.
Solution Approach 2:
The system measures multiple surface property parameters from different directions, including surface roughness, uniformity, and directional reflectivity. By monitoring changes in these parameters over time, the system can detect the optimal dressing timing based on actual surface condition changes rather than following fixed schedules, preventing both premature and excessive dressing operations.
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 improves the accuracy of surface property measurement and judgment, allowing for optimized dressing conditions and reduced consumables, thereby extending the life of dressers and enhancing polishing performance.
Implementation Method 1
a light-emitting structure configured to irradiate the polishing pad with light from a plurality of directions as viewed from a polishing-surface side of the polishing pad; and a light-receiving structure configured to receive reflected light traveling in a plurality of directions from the surface of the polishing pad
Data Source
AI summary
The present invention relates to a surface property measuring apparatus for a polishing pad used for polishing a substrate, such as a semiconductor wafer, a surface property measuring method for a polishing pad, and a surface property judging mehod for a polishing pad. The surface property measuring apparatus (30) includes: a light-emitting structure (32) configured to irradiate the polishing pad (2) with light from a plurality of directions as viewed from a polishing surface (2a) of the polishing pad (2); and a light-receiving structure (32) configured to receive reflected light traveling in a plurality of directions from the surface of the polishing pad (2).