Bernoulli Chuck Liquid Supply to Prevent Wafer Surface Drying

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Solution Overview

Problem

Conventional Bernoulli chucks used for supporting wafers in manufacturing processes dry out the surface, leading to attachment of foreign matters and reduced suction force, which can cause wafer misalignment and defects.

Innovation Solution

A workpiece supporting apparatus with a Bernoulli chuck that emits a gas to generate suction force and a liquid ejection member surrounding the chuck to prevent drying, maintaining suction force while supplying liquid to the surface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If compressed air is supplied to the Bernoulli chuck, then the suction force is sufficient to support the workpiece, but the surface of the workpiece dries out and foreign matters attach to it

Engineering Contradiction:

Improvesuction forceVSAvoidsurface drying and foreign matter attachment

Core Design Contradiction:

ForceVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a liquid (water) as an intermediary substance between the compressed air and the workpiece surface. The liquid is supplied through a liquid supply hole in the chuck, forming a liquid layer that prevents direct contact between compressed air and the workpiece surface, thereby preventing surface drying and foreign matter attachment while allowing the compressed air to maintain suction force through the liquid medium

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If pure water is supplied to the Bernoulli chuck to prevent surface drying, then the workpiece surface remains wet, but the suction force decreases

Engineering Contradiction:

Improvesurface drying preventionVSAvoidsuction force

Core Design Contradiction:

Object-affected harmful factorsVSForce

Solution Approach 1:

The patent applies local quality by supplying liquid only at specific locations (through the liquid supply hole in the chuck) rather than uniformly across the entire chuck surface. This localized liquid supply prevents surface drying only where needed while minimizing the impact on overall suction force. Additionally, the liquid is supplied in a controlled manner to form a thin film that prevents drying without significantly interfering with the gas flow's suction capability

Inventive Principle:

Principle #3Local quality

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

Prevents surface drying of the workpiece, maintains suction force, and effectively removes polishing debris, enhancing wafer processing reliability by preventing misalignment and defects.

Implementation Method 1

The Bernoulli chuck is a chuck configured to generate a suction force by ejecting a fluid using Bernoulli's theorem

Methodology Applied

Scientific EffectBernoulli's theorem: Bernoulli Effect

Data Source

PatentUS11804398B2Workpiece supporting apparatus and workpiece supporting method

Publication Date: 2023.10.31 EBARA CORP

AI summary

A workpiece supporting apparatus capable of preventing a surface of a workpiece from drying out while maintaining a suction force when supporting the workpiece with a Bernoulli chuck is disclosed. The workpiece supporting apparatus includes a Bernoulli chuck configured to generate a suction force by emitting a gas; and a liquid ejection member surrounding the Bernoulli chuck and configured to discharge a liquid around the Bernoulli chuck.