Optical Brush Distance Control for Semiconductor Wafer Cleaning

Solution Overview

Problem

In semiconductor wafer cleaning, precise control of brush separation distance is crucial to avoid scratching from tight distances and incomplete removal of residual particles, which affects wafer yield and reliability, especially as semiconductor processes advance to smaller line widths.

Innovation Solution

A cleaning apparatus with at least one rotary brush equipped with an optical sensing device to accurately measure and adjust the separation distance between the brush and the semiconductor wafer, using a controller and actuator to maintain a desired separation distance, ensuring effective removal of residual particles without scratching.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the brush separation distance is reduced to improve cleaning effectiveness, then residual particles are removed more effectively, but the risk of scratching the semiconductor wafer increases

Engineering Contradiction:

Improvecleaning effectivenessVSAvoidwafer scratching

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces mechanical pressure sensors and torque monitoring systems with an optical sensing system that uses light to measure brush-to-wafer separation distance. This substitution enables non-contact measurement, eliminating the mechanical complexity and improving measurement precision while maintaining cleaning effectiveness without causing scratches.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent implements a feedback control system where the optical sensor continuously measures the separation distance and feeds this information back to the control system, which adjusts the brush position to maintain the optimal separation distance. This ensures consistent cleaning effectiveness while preventing scratches by maintaining precise control over the brush-wafer interaction.

Inventive Principle:

Principle #23Feedback

2Reliability

If the brush separation distance is increased to prevent scratching, then wafer safety is improved, but cleaning effectiveness decreases and residual particles remain

Engineering Contradiction:

Improvewafer safetyVSAvoidcleaning effectiveness

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent replaces mechanical pressure sensors and torque monitoring systems with an optical sensing system that uses light to measure brush-to-wafer separation distance. This substitution enables non-contact measurement, eliminating the mechanical complexity and improving measurement precision while maintaining cleaning effectiveness without causing scratches.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent implements a feedback control system where the optical sensor continuously measures the separation distance and feeds this information back to the control system, which adjusts the brush position to maintain the optimal separation distance. This ensures consistent cleaning effectiveness while preventing scratches by maintaining precise control over the brush-wafer interaction.

Inventive Principle:

Principle #23Feedback

3Ease of operation

If conventional pressure sensors or torque monitoring are used to control brush position, then basic position control is achieved, but measurement precision and control accuracy are insufficient for advanced semiconductor processes

Engineering Contradiction:

Improvebrush position controlVSAvoidseparation distance measurement accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent replaces mechanical pressure sensors and torque monitoring systems with an optical sensing system that uses light to measure brush-to-wafer separation distance. This substitution enables non-contact measurement, eliminating the mechanical complexity and improving measurement precision while maintaining cleaning effectiveness without causing scratches.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 solution improves wafer yield and efficiency by precisely controlling the brush separation distance, preventing scratches and ensuring complete removal of residual particles, thereby enhancing the reliability of semiconductor wafers.

Implementation Method 1

at least one optical sensing device associated with the at least one rotary brush to sense a distance between a reference position thereon and the semiconductor wafer

Methodology Applied

Scientific EffectOptical detection: Reflection

Data Source

PatentUS8992692B2Adjustable brush cleaning apparatus for semiconductor wafers and associated methods

Publication Date: 2015.03.31 STMICROELECTRONICS INT NV

AI summary

A cleaning apparatus for cleaning a semiconductor wafer includes a rotary brush to be positioned to clean the semiconductor wafer, and an optical sensing device associated with the rotary brush to sense a separation distance between a reference position thereon and the semiconductor wafer. An actuator is coupled to the optical sensing device to position the rotary brush based upon the sensed separation distance.