Spin Cup Geometry for Wafer Cleaning Mist Suppression

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Solution Overview

Problem

During the cleaning of semiconductor wafers using a spin cleaning apparatus, a portion of the cleaning solution mist is bounced and adhered to the wafer surface, leading to chemical reactions and light point defects, which reduce yield.

Innovation Solution

A cleaning apparatus with a spin cup having an annular side wall, an inclined portion, and a bent portion is designed. The spin cup's geometry, including the inclination angle and width of the inclined portion, is optimized to prevent mist from adhering to the wafer by ensuring it is exhausted through a gap between the spin cup and the rotating table.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of substance

If a spin cup is used to collect scattered cleaning solution, then cleaning solution can be contained, but mist is bounced and adhered to the wafer surface causing light point defects

Engineering Contradiction:

Improvecleaning solution containmentVSAvoidlight point defects on wafer

Core Design Contradiction:

Loss of substanceVSObject-affected harmful factors

Solution Approach 1:

The spin cup includes an inclined portion that extends upward from the side wall, creating a three-dimensional structure that intercepts mist in the vertical dimension before it can bounce off the side wall and adhere to the wafer. This upward extension adds a new spatial dimension to the containment approach.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The inclined portion acts as an intermediary element between the side wall and the wafer. It intercepts and redirects the mist flow, preventing direct contact between the bounced mist and the wafer surface, thus serving as a mediating structure that resolves the harmful effect.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Quantity of substance

If the spin cup side wall is positioned high to collect mist, then more mist is captured, but mist bounces off the side wall and adheres to the wafer

Engineering Contradiction:

Improvemist collection amountVSAvoidwafer surface quality

Core Design Contradiction:

Quantity of substanceVSManufacturing precision

Solution Approach 1:

Instead of simply increasing the height of the vertical side wall, the invention adds an upwardly extending inclined portion that creates a sloped surface. This introduces a dimensional transition that allows mist to be captured and redirected along the incline rather than bouncing vertically back toward the wafer.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The inclined portion provides a sloped, curved surface that redirects mist flow in a controlled manner. The angular transition from vertical to sloped surface creates a smooth flow path that prevents abrupt bouncing and redirects mist away from the wafer while maintaining effective containment.

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Productivity

If cleaning solution is sprayed at high rate to clean wafer effectively, then cleaning performance improves, but more mist is generated and scattered

Engineering Contradiction:

Improvecleaning efficiencyVSAvoidmist generation

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The invention converts the harmful scattered mist generated by high-rate cleaning into a controlled flow that is redirected by the inclined portion. The mist that would normally bounce harmfully is instead channeled along the slope and contained, transforming a harmful byproduct into a controlled element.

Inventive Principle:

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

Solution Approach 2:

The inclined portion serves as an intermediary structure that intercepts the mist generated during high-efficiency cleaning. It provides a transition zone that captures and redirects the mist flow, allowing high-rate cleaning to proceed while preventing harmful mist adhesion to the wafer.

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 optimized spin cup design effectively prevents the cleaning solution mist from adhering to the semiconductor wafer, reducing light point defects and improving yield.

Implementation Method 1

a gas supply portion that is provided in an upper part of the chamber and supplies a gas downward

Methodology Applied

Scientific EffectGas flow: Convection

Implementation Method 2

the cleaning solutions are scattered as a fine mist (hereinafter may simply be referred to as a 'mist') outward in radial directions of the semiconductor wafer by centrifugal force

Methodology Applied

Scientific EffectCentrifugal force: Centrifugal Force

Data Source

PatentUS12205830B2Cleaning apparatus for semiconductor wafer and method of cleaning semiconductor wafer

Publication Date: 2025.01.21 SUMCO CORP

AI summary

Provided is a cleaning apparatus and a cleaning method for semiconductor wafers that can hinder a mist of a cleaning solution from being adhered to a surface of a semiconductor wafer during cleaning of the semiconductor wafer. In a cleaning apparatus 1 for a semiconductor wafer, a spin cup 20 has an annular side wall portion 21; an inclined portion 22 that is inclined toward the rotating table 13; and an annular bent portion 23. The height position h21 of the upper end portion 21c of the side wall portion 21 is set at a position lower than the height position h14a of the upper end portion 14a of the wafer retainer portion 14, and the inclination angle θ22 of the inclined portion to a horizontal plane and the width w of the inclined portion satisfy a formula (A):θ22(°)≥−0.65×w(mm)+72.9° (A).