Post-CMP Wafer Cleaning Using Acoustic Streaming for Particle Reattachment

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Solution Overview

Problem

Existing post-CMP cleaning processes face challenges in effectively removing particles of varying sizes from semiconductor wafers, particularly small particles that reattach to the surface during the cleaning process, leading to reduced cleaning efficiency and potential contamination of cleaning tools.

Innovation Solution

A multi-stage cleaning process is employed, combining contact and non-contact methods using brush rollers and a vibrating device with adjustable frequencies to deliver cleaning fluids, allowing for the removal of particles of different sizes through controlled scrubbing and acoustic streaming.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional brush cleaning is used to remove particles from wafer surfaces, then large particles can be effectively removed, but small particles reattach to the surface during the cleaning process

Engineering Contradiction:

Improveparticle removal effectivenessVSAvoidparticle reattachment prevention

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The cleaning process is divided into multiple sequential stages: a first cleaning stage using contact brushes for large particles, and a second cleaning stage using acoustic waves for small particles. This segmentation allows each stage to target specific particle sizes appropriately, preventing small particles from reattaching while effectively removing large particles.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Acoustic waves (a form of mechanical vibration) are applied in the second cleaning stage to prevent small particles from reattaching to the wafer surface. The vibration creates a cleaning fluid environment that keeps particles suspended and prevents reattachment, thereby improving reliability for small particle removal.

Inventive Principle:

Principle #18Mechanical vibration

2Productivity

If contact cleaning methods are used to remove particles, then cleaning effectiveness is improved, but tool contamination increases

Engineering Contradiction:

Improvecleaning efficiencyVSAvoidtool contamination

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent replaces the mechanical contact cleaning method with an acoustic wave-based cleaning method in the second cleaning stage. This substitution eliminates direct mechanical contact between cleaning tools and the wafer surface, thereby preventing tool contamination while maintaining cleaning effectiveness for small particles.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

A cleaning fluid acts as an intermediary medium between the acoustic waves and the wafer surface. The acoustic waves transmit energy through the cleaning fluid to remove particles without requiring direct contact between the cleaning tool and the wafer, thus preventing tool contamination while maintaining cleaning efficiency.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Device complexity

If a single cleaning stage is used, then the process is simple, but particles of varying sizes cannot be effectively removed

Engineering Contradiction:

Improvecleaning process simplicityVSAvoidmulti-size particle removal

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The cleaning process is segmented into two distinct stages: a first cleaning stage using contact brushes optimized for large particles, and a second cleaning stage using acoustic waves optimized for small particles. This segmentation enables effective removal of particles across a wide size range, improving manufacturing precision without excessive complexity.

Inventive Principle:

Principle #1Segmentation

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

The method enhances cleaning efficiency by effectively removing particles ranging from large to small sizes, minimizing reattachment and tool contamination, thereby improving the quality of post-CMP cleaning processes.

Implementation Method 1

The vibrating device is configured to provide the cleaning fluid with a specific frequency which is at least greater than 100 MHz while the rotating platen is rotating the semiconductor wafer, so that particles on the semiconductor wafer are removed by the cleaning fluid

Methodology Applied

Scientific EffectAcoustic streaming: Ultrasound

Data Source

PatentUS12538739B2Post CMP cleaning apparatus and post CMP cleaning methods

Publication Date: 2026.01.27 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A post CMP cleaning apparatus is provided. The post CMP cleaning apparatus includes a cleaning stage. The post CMP cleaning apparatus also includes a rotating platen disposed in the cleaning stage, and the rotating platen is configured to hold and rotate a semiconductor wafer. The post CMP cleaning apparatus further includes a vibrating device disposed over the rotating platen. The post CMP cleaning apparatus further includes a solution delivery module disposed near the vibrating device and configured to deliver a cleaning fluid to the semiconductor wafer. The vibrating device is configured to provide the cleaning fluid with a specific frequency which is at least greater than 100 MHz while the rotating platen is rotating the semiconductor wafer, so that particles on the semiconductor wafer are removed by the cleaning fluid.