Wafer Edge Polishing Sensor Head for Accurate Endpoint Detection

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Solution Overview

Problem

Accurately detecting the polishing amount at the peripheral portion of a wafer is difficult due to its inclined and small area, which affects the determination of the polishing end point.

Innovation Solution

A polishing apparatus with a sensor structure comprising a sensor head and displacement sensor to detect the polishing amount, synchronized with the polishing head's tilt angle, and a control device to manage operations for precise polishing end point determination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a conventional polishing apparatus is used to polish the peripheral portion of the wafer, then the polishing process can be performed, but the polishing amount cannot be detected with high accuracy due to the inclined and small area of the peripheral portion

Engineering Contradiction:

Improvepolishing amount detection accuracyVSAvoiddifficulty of detecting polishing amount at peripheral portion

Core Design Contradiction:

Measurement precisionVSDifficulty of detecting and measuring

Solution Approach 1:

The sensor structure is segmented into a sensor head and a displacement sensor, allowing the detection function to be separated from the polishing function. This segmentation enables accurate measurement at the difficult-to-measure peripheral portion by using a dedicated sensor component that can be positioned and oriented independently.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The sensor head acts as an intermediary between the displacement sensor and the peripheral portion of the wafer. It transmits the displacement caused by polishing to the displacement sensor, enabling indirect but accurate measurement of the polishing amount at the inclined peripheral surface.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If the sensor structure is added to detect polishing amount, then measurement accuracy is improved, but device complexity increases

Engineering Contradiction:

Improvepolishing amount detection accuracyVSAvoidcomplexity of polishing apparatus

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The sensor structure, particularly the sensor head, serves multiple functions: it acts as a contact surface for the peripheral portion, a transmission element for displacement, and a positioning component. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The sensor head merges the functions of contact surface and displacement transmission into a single component. By combining these functions, the patent avoids adding separate contact surfaces and transmission mechanisms, thus reducing the overall complexity increase despite adding detection capability.

Inventive Principle:

Principle #5Merging (Combining)

3Measurement precision

If the sensor head contacts the peripheral portion directly, then polishing amount can be detected, but the sensor structure becomes more complex requiring additional mechanisms

Engineering Contradiction:

Improvepolishing amount detection accuracyVSAvoidcomplexity of sensor structure

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

Instead of making the displacement sensor complex to adapt to the inclined peripheral surface, the patent inverts the approach by using a simple sensor head that contacts the peripheral portion and transmits displacement to a straightforward displacement sensor. The complexity is inverted from the sensing mechanism to the simple contact-and-transmit geometry.

Inventive Principle:

Principle #13The other way round (Inversion)

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

Enables high-accuracy detection of the polishing amount at the peripheral portion of the wafer, ensuring precise polishing end point determination.

Implementation Method 1

a displacement sensor configured to detect the polishing amount of the peripheral portion by a displacement of the sensor head

Methodology Applied

Scientific EffectDisplacement measurement: Displacement

Implementation Method 2

a biasing member configured to bias the sensor head toward the peripheral portion

Methodology Applied

Scientific EffectMechanical biasing force: Mechanical Force

Implementation Method 3

a polishing apparatus including an abrasive such as an abrasive tape is used to polish the peripheral portion of the wafer and remove the films from the peripheral portion

Methodology Applied

Scientific EffectAbrasion: Abrasion

Data Source

PatentEP4620615A1Polishing device

Publication Date: 2025.09.24 EBARA CORP

Figure 1A~1B
Figure 2
Figure 3

AI summary

The present invention relates to a polishing apparatus. The polishing apparatus includes a sensor structure (100) configured to detect a polishing amount of a peripheral portion of a substrate (W). The sensor structure (100) includes a sensor head (102) having a contact surface (102a), and a displacement sensor (101) configured to detect the polishing amount of the peripheral portion of the substrate (W) based on a displacement of the sensor head (102).