Electrostatic Chuck Tray for Wafer Fixation and Temperature Control

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Solution Overview

Problem

Conventional methods for fixing wafers to trays for plasma processing are inefficient, requiring significant time, reducing the effective processing area, and necessitating post-treatments, while also struggling with temperature control and stability.

Innovation Solution

A wafer-transporting tray equipped with an electrostatic chuck made of conductive material and an insulating surface, using a spring-type terminal for electrostatic chucking, which allows for efficient temperature control and rapid fixation without reducing the processing area, and includes sealing to prevent heat medium leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a pressing jig is used to fix the wafer to the tray, then the wafer can be held securely, but the fixation process requires much time and the effective processing area is reduced due to dead areas at the margins

Engineering Contradiction:
Improvefixation stabilityVSAvoidfixation time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent replaces the mechanical pressing jig system with an electrostatic chucking system. The electrostatic chuck uses electrostatic forces to hold the wafer firmly on the tray without requiring mechanical pressing, thereby eliminating the time-consuming fixation process while maintaining secure holding. The electrostatic field is generated by applying voltage to electrodes on the tray surface, creating attraction forces that secure the wafer without contact.

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

2Reliability

If a pressing jig is used to fix the wafer, then the wafer can be held securely, but the effective processing area is considerably reduced due to dead areas at the margins

Engineering Contradiction:
Improvefixation stabilityVSAvoideffective processing area
Core Design Contradiction:
ReliabilityVSArea of stationary object

Solution Approach 1:

The electrostatic chucking system replaces mechanical pressing, allowing the entire wafer surface to remain accessible for processing. Without physical contact from pressing jigs at the margins, the effective processing area is maximized while the electrostatic field provides uniform holding across the wafer surface.

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

3Reliability

If adhesive sheet is used to fix the wafer to the tray, then the wafer can be adhered to the tray, but the adhesion process requires much time and post-treatments are necessary

Engineering Contradiction:
Improvefixation stabilityVSAvoidadhesion time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent replaces adhesive bonding with electrostatic attraction. The electrostatic chuck generates electrostatic forces through applied voltage to electrodes on the tray, creating firm adhesion without requiring adhesive materials. This eliminates the time-consuming adhesion process and eliminates the need for post-treatments to remove adhesive residues.

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

4Reliability

If mechanical clamping member is used to fix the tray to the stage, then the tray can be held securely, but the fixation process is complex and time-consuming

Engineering Contradiction:
Improvetray fixation stabilityVSAvoidfixation mechanism complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces mechanical clamping members with an electrostatic chucking system for tray fixation. The electrostatic field is generated by applying voltage to electrodes on the stage, creating attraction forces that secure the tray without mechanical clamps. This simplifies the fixation mechanism while maintaining secure holding.

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

5Reliability

If conventional fixation methods are used, then the wafer can be fixed to the tray, but temperature control of the wafer is difficult

Engineering Contradiction:
Improvefixation stabilityVSAvoidwafer temperature control
Core Design Contradiction:
ReliabilityVSTemperature

Solution Approach 1:

The electrostatic chuck system serves multiple functions: it provides secure wafer fixation through electrostatic attraction and simultaneously enables temperature control through integrated heating elements. The heating elements can be controlled independently to maintain optimal wafer temperature during processing, combining fixation and thermal management in a single system.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 solution enables efficient temperature control and rapid, reliable fixation of wafers without reducing the processing area, saving time and labor, and eliminating the need for post-treatments.

Implementation Method 1

fixing the wafer to the tray by the electrostatic chucking

Methodology Applied
Scientific EffectElectrostatic force: Electrostatics

Implementation Method 2

cool the tray 102 and the wafer S at the same time

Methodology Applied
Scientific EffectHeat transfer: Conduction (thermal)

Data Source

PatentEP2400536B1Wafer conveying tray and method of securing wafer on tray
Publication Date: 2020.04.15 ULVAC INC
  • EP2400536B1 patent drawingFigure 1~2
  • EP2400536B1 patent drawingFigure 3~4
  • EP2400536B1 patent drawingFigure 5~6

AI summary

A tray for transporting a wafer is herein provided, which can control the temperature of the wafer upon the processing thereof, and which can easily fix the wafer without reducing the effective area on the surface of the wafer and without requiring much time for the adhesion of the wafer thereto and without requiring any post-treatment after the wafer is detached from or attached to the tray. The tray 302 is one which comprises a base body consisting of an insulating material and an electrostatic chuck electrode 306 embedded in the base body, wherein the terminal at a load-dispatching or power supply portion for energizing the electrostatic chuck electrode is a spring-type terminal 305a, the spring-type terminal is so designed that the tip of the same can come in touch with the electrostatic chuck electrode, and further the tray is so designed that a sealing member 305b is provided at the periphery of the load-dispatching portion so that any heat-exchanging medium never passes around the contact portion or area between the tip of the spring-type terminal and the electrostatic chuck electrode and that the tray can thus fixe the wafer S thereto through the electrostatic chucking. Thus, the wafer is fixed to this wafer-transporting tray by the action of the electrostatic chucking.