CMP Polishing Pad Surface Inspection via Multi-Angle Reflection

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Solution Overview

Problem

Existing methods for determining the wear and performance of polishing pads in chemical mechanical polishing (CMP) processes are inadequate, as they rely on use time and substrate count, which do not accurately reflect the pad's condition, leading to potential underutilization or overuse of pads due to unnoticed surface roughness changes.

Innovation Solution

A pad-surface determination method and system that uses multiple light emitters to irradiate the polishing pad surface at different angles, capturing reflected light to generate images, and calculates a pad-surface index value based on brightness information to assess the pad's condition, including protrusion height changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the polishing pad is replaced based on use time or substrate count, then the replacement schedule is simple to manage, but the actual surface condition and protrusion state cannot be accurately detected

Engineering Contradiction:

Improvereplacement schedule managementVSAvoidsurface condition detection accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent replaces mechanical/wear-based replacement criteria (use time, substrate count) with an optical detection system that measures surface protrusions using reflected light images, enabling direct observation of pad surface condition

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces light as an intermediary medium to detect pad surface conditions. By irradiating the pad surface with light and capturing reflected light images, the system can non-contactly measure protrusion heights and surface roughness without physical contact

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the polishing pad is replaced early to ensure performance, then polishing quality is maintained, but pad utilization is reduced and waste increases

Engineering Contradiction:

Improvepolishing qualityVSAvoidpad utilization

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The patent implements a feedback mechanism where the pad surface condition is continuously monitored through optical measurement, and replacement decisions are based on real-time data about protrusion height changes rather than fixed schedules, allowing timely replacement only when needed

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent performs preliminary detection of pad surface conditions before replacement is needed by continuously monitoring protrusion changes, enabling proactive replacement decisions based on actual wear state rather than reactive schedule-based replacement

Inventive Principle:

Principle #10Preliminary action

3Productivity

If the polishing pad is used longer than expected, then pad utilization increases, but surface roughness changes are not detected until performance deteriorates

Engineering Contradiction:

Improvepad utilizationVSAvoidsurface roughness change detection

Core Design Contradiction:

ProductivityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent applies partial action by measuring only the protrusion height at specific locations on the pad surface rather than requiring complete surface analysis, enabling early detection of wear patterns before overall performance deteriorates

Inventive Principle:

Principle #16Partial or excessive action

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

Accurately determines the polishing pad's surface condition, allowing for timely replacement and maintaining optimal polishing performance by identifying when the pad reaches the end of its service life without requiring prior knowledge of optimal incident angles.

Implementation Method 1

irradiating a target area in the polishing surface with a plurality of lights from a plurality of light emitters at different incident angles

Methodology Applied

Scientific EffectLight: Light

Implementation Method 2

receiving a plurality of reflected lights from the target area by an imaging device

Methodology Applied

Scientific EffectReflection: Reflection

Data Source

PatentUS20260001194A1Pad-surface determination method and pad-surface determination system

Publication Date: 2026.01.01 EBARA CORP

AI summary

A pad-surface determination method that can appropriately determine a surface property of a polishing pad including a condition of protrusions formed on a polishing surface of the polishing pad is disclosed. The pad-surface determination method includes: irradiating a target area in the polishing surface with a plurality of lights from a plurality of light emitters 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. A protrusion is formed on the polishing surface in the target area.