Polishing Pad Surface Detection via Multi-Angle Illumination
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Solution Overview
Problem
The existing methods for determining the surface condition of polishing pads in semiconductor manufacturing, such as CMP, are inadequate as they rely on wear indicators like time and substrate count, which do not accurately reflect the pad's actual condition, leading to premature replacement or continued use beyond service life, affecting polishing performance.
Innovation Solution
A pad surface determining method and system that uses multiple light sources with different incident angles to irradiate the polishing pad, capturing reflected images to generate pad-surface index values based on brightness information, allowing for accurate assessment of recess depth and debris accumulation without requiring an optimal incident angle, and utilizing machine learning models for determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple light sources with different incident angles are used to irradiate the polishing pad, then measurement precision of surface condition is improved, but device complexity increases
Solution Approach 1:
The patent applies dimensionality change by introducing multiple light sources from different incident angles (spatial dimension) to capture surface condition information that cannot be obtained from a single angle. This multi-angle illumination creates complementary images that, when processed, provide comprehensive measurement of recess depth and debris accumulation, resolving the contradiction between measurement precision and device complexity.
2Measurement precision
If machine learning models are used for surface property determination, then measurement precision is improved, but loss of time for processing increases
Solution Approach 1:
The patent implements preliminary action by pre-training machine learning models with extensive surface condition data before actual measurement. The models are prepared in advance to recognize patterns of recess depth and debris accumulation, enabling rapid inference during operation. This pre-processing of the analytical capability reduces real-time processing time while maintaining high measurement precision.
3Ease of operation
If polishing pad replacement is based on time or substrate count, then ease of operation is improved, but reliability of polishing performance deteriorates
Solution Approach 1:
The patent implements feedback by continuously monitoring the actual surface condition of the polishing pad through multi-angle light reflection imaging and machine learning analysis. This real-time feedback on recess depth and debris accumulation allows dynamic adjustment of replacement timing based on actual wear state rather than fixed schedules, ensuring reliable polishing performance while maintaining operational simplicity through automated monitoring.
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 enables precise monitoring of polishing pad surface conditions, ensuring timely replacement and maintaining polishing performance by accurately assessing the pad's state, independent of pad type or location, thus optimizing the polishing process.
Implementation Method 1
irradiating a target area in the polishing surface with a plurality of lights from a plurality of light sources at different incident angles; receiving a plurality of reflected lights from the target area by an imaging device
Data Source
AI summary
A pad surface determining method that can appropriately determine a surface property of a polishing pad including a condition of recess (e.g., groove or hole) formed in a polishing surface of the polishing pad is disclosed. The pad surface determining method includes: irradiating a target area in the polishing surface with a plurality of lights from a plurality of light sources at different incident angles; receiving a plurality of reflected lights from the target area by an imaging device; generating a plurality of images corresponding to the different incident angles by the imaging device; and determining the surface property of the polishing pad based on at least one of the plurality of images.