Cleaning Member Cleanliness Detection Using Crystal Oscillator Feedback

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Solution Overview

Problem

Current methods for evaluating the cleanliness of cleaning members used in semiconductor substrate cleaning are inadequate, particularly in detecting internal contaminants and determining the adsorption characteristics, leading to reduced cleaning effectiveness and increased contamination risks due to the miniaturization of substrates.

Innovation Solution

A method involving self-cleaning of the cleaning member by releasing contaminants into a cleaning liquid, followed by contacting the discharged liquid with a crystal oscillator to measure frequency responses, allowing for accurate detection of even small contaminant masses and determining cleanliness based on these measurements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional defect inspection devices are used to evaluate cleanliness of cleaning members, then throughput is reduced when all substrates are evaluated, but when sampling is performed, timely evaluation becomes difficult and measurement precision decreases

Engineering Contradiction:

ImprovethroughputVSAvoidcleanliness evaluation accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent replaces the conventional defect inspection device (optical/mechanical system) with a quartz crystal oscillator-based measurement system. The oscillator's frequency shift directly measures contaminant mass on the cleaning member, enabling real-time, high-precision cleanliness evaluation without reducing throughput. This substitution of measurement mechanism resolves the contradiction between productivity and measurement precision.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If cleaning members are used for long-term operation, then productivity is maintained, but cleaning power decreases due to contamination accumulation

Engineering Contradiction:

Improvecontinuous operation capabilityVSAvoidcleaning power

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent implements a feedback mechanism where the quartz crystal oscillator continuously monitors contaminant accumulation on the cleaning member during operation. When the measured contaminant mass reaches a threshold, the system signals that the cleaning member needs replacement or cleaning. This real-time feedback enables optimal timing for maintenance, maintaining both productivity and cleaning power (reliability).

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system performs preliminary detection of contaminant accumulation before it significantly impacts cleaning performance. By monitoring the cleaning member's contamination level in real-time, the system allows for proactive replacement or cleaning of the cleaning member, preventing degradation of cleaning power while maximizing productive usage.

Inventive Principle:

Principle #10Preliminary action

3Ease of operation

If ultrasonic vibration is applied to remove superficial contaminants, then ease of operation is improved, but internal contaminants deep within the cleaning member cannot be effectively removed

Engineering Contradiction:

Improvecontaminant removal capabilityVSAvoidinternal contamination removal

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent introduces a cleaning liquid as an intermediary medium that penetrates deep into the cleaning member's porous structure. The cleaning liquid dissolves and carries out internal contaminants that ultrasonic vibration cannot reach. The quartz crystal oscillator then measures the contaminant mass in the discharged cleaning liquid, providing indirect detection of internal contamination. This intermediary approach resolves the limitation of ultrasonic vibration for deep contamination removal.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 evaluation of cleaning member cleanliness and adsorption characteristics, reducing the risk of residual contaminants and improving cleaning performance by accurately determining when cleaning members need replacement.

Implementation Method 1

measuring a frequency response of a crystal oscillator in which contaminants are attached onto an electrode

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

a method for supplying the cleaning liquid to the cleaning member and applying ultrasonic vibration to the cleaning liquid

Methodology Applied

Scientific EffectUltrasonic vibration: Ultrasonic Vibration

Data Source

PatentUS12101073B2Method for determining a cleanliness of a cleaning member

Publication Date: 2024.09.24 EBARA CORP

AI summary

In a method for determining cleanliness of a cleaning member that contacts a substrate and with which scrub cleaning is performed, the method includes a first step of self-cleaning a cleaning member by releasing contaminants from the cleaning member into a cleaning liquid, and a second step of bringing a self-cleaning discharged liquid into contact with an electrode of a crystal oscillator, attaching the contaminants contained in the discharged liquid onto the electrode of the crystal oscillator, then measuring a frequency response of the crystal oscillator in which the contaminants are attached onto the electrode, and determining cleanliness of the cleaning member based on the measured frequency response.