Double-Surface Electrostatic Attractor for Wafer Transfer Tray Fixation

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Solution Overview

Problem

The existing plasma treatment apparatuses for semiconductor wafers face challenges in achieving uniform and efficient contact between the wafer transfer tray and the supporter, leading to reduced cooling efficiency and increased complexity in fixing the tray, due to the use of mechanical clamps which can decrease adhesion near the central portion.

Innovation Solution

A plasma treatment apparatus with a wafer transfer tray that employs a double-surface electrostatic attractor, using conductive layers and a ground potential to electrostatically attract both the wafer and the supporter to the tray, reducing mechanical movable parts and enhancing uniform cooling through a cooling gas.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a mechanical clamp is used to attach the wafer transfer tray and supporter, then the tray and supporter can be mechanically fixed, but the adhesion between the tray and supporter decreases in the vicinity of the central portion

Engineering Contradiction:
Improvemechanical fixationVSAvoidadhesion
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The patent replaces the mechanical clamp system with an electrostatic attraction system. The electrostatic attractor generates electrostatic forces that hold the wafer transfer tray against the supporter without mechanical contact, thereby preserving adhesion across the entire surface including the central portion while still achieving secure fixation.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent extracts the mechanical clamp component from the system and replaces it with an electrostatic field-based fixation mechanism. This removal of mechanical elements eliminates the interference with adhesion while maintaining the essential function of securing the tray to the supporter.

Inventive Principle:
Principle #2Taking out (Extraction)

2Loss of energy

If the wafer transfer tray and supporter are made to closely contact to minimize cooling gas leakage, then cooling efficiency improves, but the operation becomes complicated due to mechanical clamp requirements

Engineering Contradiction:
Improvecooling gas leakageVSAvoidfixation operation
Core Design Contradiction:
Loss of energyVSEase of operation

Solution Approach 1:

The patent replaces complex mechanical clamp operations with simple electrostatic field activation. By applying voltage to the electrostatic attractor, the tray is automatically held against the supporter with uniform pressure, achieving close contact for minimal gas leakage without complicated mechanical adjustment operations.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If pressing means is used to fix wafers to the wafer transfer tray, then wafer fixation is achieved, but the effective area in the wafer surface is reduced and the process becomes time-consuming

Engineering Contradiction:
Improvewafer fixationVSAvoidprocessing efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent replaces mechanical pressing means with electrostatic attraction for wafer fixation. The electrostatic field acts instantaneously across the entire wafer surface without physical contact, achieving secure fixation while maintaining 100% effective wafer area and eliminating time-consuming pressing operations.

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

This configuration allows for efficient and uniform plasma treatment of wafers by ensuring close contact between the tray and the supporter, reducing cooling gas loss and simplifying the fixation process, while maintaining accurate and uniform plasma treatment across the wafer surface.

Implementation Method 1

a double-surface electrostatic attractor configured to electrostatically attract the wafer to the first surface of the wafer transfer tray and electrostatically attract the supporter to the second surface of the wafer transfer tray

Methodology Applied
Scientific EffectElectrostatic attraction: Electrostatics

Implementation Method 2

the plasma treatment apparatus configured to form a flow path through which a cooling gas flows between the wafer transfer tray and a supporter that supports the wafer transfer tray, and cool the wafer transfer tray using a cooling gas

Methodology Applied
Scientific EffectConvection cooling: Convection

Data Source

PatentEP3098838B1Plasma treatment device and wafer transportation tray
Publication Date: 2021.01.27 ULVAC INC
  • EP3098838B1 patent drawingFigure 1
  • EP3098838B1 patent drawingFigure 2
  • EP3098838B1 patent drawingFigure 3~4

AI summary

A plasma treatment apparatus includes a wafer transfer tray having a first surface and a second surface opposite to the first surface and configured to hold a wafer on the first surface, a cooling unit configured to cool the wafer transfer tray, a conductive supporter configured to support the second surface of the wafer transfer tray, and a double-surface electrostatic attractor configured to electrostatically attract the wafer to the first surface of the wafer transfer tray and electrostatically attract the supporter to the second surface of the wafer transfer tray.