Wafer Back Surface Cleaning via Scrub and Two-Fluid Jet

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional cleaning techniques struggle to effectively remove foreign matter, such as polishing debris, from the back surface of wafers, leading to potential short-circuits, patterning deviations, and contamination of other wafers in a cassette.

Innovation Solution

A substrate processing apparatus and method that combines scrub cleaning and two-fluid cleaning processes in a single chamber, using a scrub cleaning tool and a two-fluid nozzle to efficiently remove particles from the back surface of wafers, preventing debris from remaining on the wafer after cleaning.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a polishing tool is used to scrape off the back surface to remove foreign matter, then foreign matter removal efficiency is improved, but polishing debris remains on the back surface

Engineering Contradiction:

Improveforeign matter removal efficiencyVSAvoidpolishing debris

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The cleaning process is divided into two distinct stages: first the polishing stage to remove foreign matter, then the cleaning stage to remove polishing debris. This segmentation allows each process to optimize for its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A cleaning fluid is introduced as an intermediary substance between the polishing tool and the back surface. The cleaning fluid carries away polishing debris from the back surface, preventing debris accumulation while maintaining the effectiveness of the polishing process.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If conventional scrub cleaning is used on the back surface, then cleaning is performed, but foreign matter covered with deposited film cannot be removed

Engineering Contradiction:

Improvecleaning process simplicityVSAvoidforeign matter removal efficiency

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The invention merges polishing and cleaning functions into a single integrated process. The polishing tool simultaneously performs both polishing (to remove covered foreign matter) and cleaning (to remove debris), combining two previously separate steps into one efficient operation.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

A composite cleaning fluid is used that combines multiple functional components: surfactants for wetting and emulsification, solvents for dissolving deposited films, and abrasives for mechanical removal of stubborn foreign matter. This composite fluid enables the removal of foreign matter covered with deposited film that conventional cleaning cannot handle.

Inventive Principle:

Principle #40Composite materials

3Reliability

If the back surface is cleaned after polishing, then foreign matter is removed, but polishing debris may fall onto other wafers in the cassette

Engineering Contradiction:

Improveback surface cleanlinessVSAvoiddebris contamination of other wafers

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The cleaning fluid, which becomes contaminated with polishing debris during the cleaning process, is then used to rinse other wafers in the cassette. The contaminated fluid safely contains the debris, preventing it from falling onto other wafers, while the rinsing action removes any remaining debris from the back surfaces.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The cleaning fluid acts as an intermediary carrier that traps and transports polishing debris away from the back surface and into the fluid medium. This prevents debris from settling on other wafers in the cassette while maintaining a clean back surface.

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

The combined scrub and two-fluid cleaning process achieves high removal efficiency of particles from the back surface of wafers in a short period, preventing debris from falling onto other wafers and ensuring cleanliness.

Implementation Method 1

a two-fluid nozzle configured to deliver a two-fluid jet to the back surface of the substrate

Methodology Applied

Scientific EffectTwo-fluid jet: Two-Phase Flow

Implementation Method 2

delivering a two-fluid jet to the back surface of the substrate

Methodology Applied

Scientific EffectFluid jet impact: Jet

Implementation Method 3

rubbing a scrub cleaning tool against the back surface of the substrate

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 4

rubbing a scrub cleaning tool against the back surface of a substrate to slightly scrape off the back surface

Methodology Applied

Scientific EffectAbrasion: Abrasion

Data Source

PatentUS10651057B2Apparatus and method for cleaning a back surface of a substrate

Publication Date: 2020.05.12 EBARA CORP

AI summary

An apparatus which can remove particles, such as polishing debris, from a back surface with high removal efficiency is provided. The apparatus includes: a substrate holder configured to rotate the substrate while holding the substrate with the back surface facing upward; a scrub cleaning tool configured to be rotatable; a two-fluid nozzle disposed above the substrate holder; and a housing defining a cleaning chamber in which the substrate holder, the scrub cleaning tool, and the two-fluid nozzle are located.