Wafer Cleaning with Radial Electroviscous Control

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Solution Overview

Problem

In semiconductor manufacturing, conventional wafer cleaning methods struggle to uniformly clean the entire surface due to radial variations in cleaning power, leading to potential damage of ultra-fine structures and inefficiencies in cleaning near the center of rotation.

Innovation Solution

A method and apparatus that applies an electric field varying in intensity based on the radial position to control the viscosity of an ion-containing cleaning liquid, ensuring uniform cleaning across the wafer surface by adjusting the spacing and intensity of the electric field.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional wafer cleaning methods are used with rotation, then cleaning is performed on the wafer surface, but cleaning power varies radially causing non-uniform cleaning

Engineering Contradiction:

Improvecleaning uniformityVSAvoidradial cleaning power distribution

Core Design Contradiction:

Manufacturing precisionVSEase of operation

Solution Approach 1:

The patent applies local quality by varying the viscosity of the cleaning liquid at different radial positions on the wafer. The cleaning liquid has higher viscosity near the center of rotation and lower viscosity at the outer edges, compensating for the radial variation in cleaning power and achieving uniform cleaning across the entire wafer surface.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the physical parameter of the cleaning liquid (viscosity) to resolve the cleaning uniformity problem. By controlling the viscosity of the cleaning liquid to vary with radial position, the system compensates for the inherent radial power distribution issues in rotational cleaning, thereby achieving consistent cleaning quality across different regions.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If excessive cleaning is performed to remove particles from ultra-fine structures, then particle removal is improved, but patterning structures may be damaged

Engineering Contradiction:

Improveparticle removal efficiencyVSAvoidpatterning structure damage

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent changes the viscosity parameter of the cleaning liquid to optimize the balance between particle removal and structure protection. By carefully controlling the viscosity within a specific range (10-100 cP), the cleaning liquid becomes sufficiently viscous to protect ultra-fine structures from damage while maintaining enough flow capability to effectively remove particles.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite cleaning liquid system that combines water with specific additives (such as surfactants or polymers) to achieve the desired viscosity range. This composite formulation provides both the protective viscosity needed for structure safety and the cleaning efficacy required for particle removal.

Inventive Principle:

Principle #40Composite materials

3Power

If high-frequency vibration is applied to cleaning liquid to improve cleaning, then cleaning power increases, but energy may be transferred to patterning structures causing damage

Engineering Contradiction:

Improvecleaning powerVSAvoidpatterning structure damage

Core Design Contradiction:

PowerVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the mechanical vibration approach with a viscosity-based cleaning mechanism. Instead of using high-frequency vibrations that risk transferring energy to and damaging patterning structures, the system uses a carefully controlled viscous cleaning liquid that provides gentle yet effective cleaning through its rheological properties, thereby avoiding mechanical damage while maintaining cleaning power.

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

Achieves uniform cleaning efficiency across the wafer surface by controlling the viscosity of the cleaning liquid, minimizing damage to ultra-fine structures and ensuring thorough cleaning regardless of radial position.

Implementation Method 1

applying an electric field varying in intensity based on the radial position to control the viscosity of an ion-containing cleaning liquid

Methodology Applied

Scientific EffectElectroviscous effect: Electroviscous Effect

Data Source

PatentUS20260068576A1Method and apparatus for nanofluid wet cleansing wafer

Publication Date: 2026.03.05 UNIV OF ULSAN FOUND FOR IND COOPERATION

AI summary

Provided are a wafer cleaning method capable of uniformly cleaning an entire area of a wafer, and a wafer cleaning apparatus to which the method is applied. The method includes positioning a cleaning tool to face a surface of the wafer requiring cleaning; supplying a cleaning liquid containing ions to an area between the wafer and the cleaning tool; adjusting a spacing between a surface of the wafer and the cleaning tool for a viscosity of the cleaning liquid therebetween to be controlled by an electric field; and relatively rotating the wafer from the cleaning tool while the electric field being applied to at least a portion of the cleaning liquid, thereby cleaning the surface of the wafer with the cleaning liquid.