Polishing Apparatus Roller Abnormality Detection via Torque Waveform Analysis

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Solution Overview

Problem

Conventional polishing apparatuses lack a means to detect abnormalities in rollers that transmit local loads, potentially leading to malfunction and disrupted normal operation during the polishing process.

Innovation Solution

A method and apparatus that measure torque changes using a torque waveform analysis, specifically through a Fourier-transform process, to determine if a roller is malfunctioning by comparing the intensity of frequency components to a predetermined threshold, allowing for the detection of abnormal rollers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If rollers are used to transmit local load to the retainer ring, then the profile of the edge portion of the wafer can be positively controlled, but there is no means to detect abnormalities in the rollers which may lead to malfunction and disrupted normal operation

Engineering Contradiction:

Improveprofile control of wafer edge portionVSAvoidroller operation reliability

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent implements a feedback mechanism by measuring torque on the rotary ring and analyzing its waveform to detect roller abnormalities. A torque sensor measures the torque while the rotary ring rotates, and a waveform analysis unit analyzes the torque waveform to detect periodic components indicating roller issues. This closed-loop feedback system enables real-time monitoring of roller health, allowing detection of abnormalities that would otherwise go unnoticed and cause malfunctions.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces direct mechanical inspection of rollers with a torque measurement and waveform analysis system. Instead of mechanically examining each roller for abnormalities, the system uses torque sensors and signal processing to indirectly detect roller issues through the torque waveform characteristics, substituting complex mechanical inspection with a more reliable sensing and analysis approach.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If continuous monitoring of roller operation is implemented, then roller abnormalities can be detected, but the device complexity increases due to additional sensors and analysis systems

Engineering Contradiction:

Improveroller abnormality detection capabilityVSAvoidtorque measurement and analysis system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The torque sensor and waveform analysis system serve multiple functions: they monitor roller operation, detect roller abnormalities, and provide diagnostic information about the polishing process. By making the torque measurement system multi-functional, the patent reduces the need for separate dedicated monitoring equipment, thereby limiting the increase in device complexity while achieving reliable roller abnormality detection.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 the detection of roller abnormalities, preventing operational disruptions and ensuring consistent performance of the polishing apparatus by identifying and addressing issues before they cause significant problems.

Implementation Method 1

measuring a torque for rotating the polishing head

Methodology Applied

Scientific EffectTorque: Torque

Implementation Method 2

performing Fourier-transform process on the torque waveform to determine an intensity of frequency component of the torque waveform

Methodology Applied

Scientific EffectFourier transform:

Implementation Method 3

The rollers are rotatable while being in rolling contact with the stationary ring

Methodology Applied

Scientific EffectRolling contact: Roller

Data Source

PatentUS11654524B2Method of detecting abnormality of a roller which transmits a local load to a retainer ring, and polishing apparatus

Publication Date: 2023.05.23 EBARA CORP

AI summary

A method of detecting abnormality of a roller which transmits a local load to a retainer ring is disclosed. The method comprises: rotating a polishing head which includes a head body and a retainer ring, the head body having a pressing surface for pressing a substrate, the retainer ring being arranged so as to surround the pressing surface; measuring a torque for rotating the polishing head, while rotating a rotary ring together with the polishing head and while exerting a local load to a stationary ring located on the rotary ring, the rotary ring being fixed to the retainer ring and having a plurality of rollers; generating a torque waveform indicating relationship between measured values of the torque for rotating the polishing head and measuring times of the torque; performing Fourier-transform process on the torque waveform to determine an intensity of frequency component of the torque waveform; and determining that at least one of the rollers malfunctions when the determined intensity of the frequency component is larger than a predetermined threshold value.