Wafer Placement Table Coupler Grooves for Thermal Stress Control

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Solution Overview

Problem

Existing wafer placement tables are susceptible to damage due to thermal stress at the interface between the central and outer circumferential portions of the cooling base, where temperature differences cause strain on the coupler.

Innovation Solution

The wafer placement table features a coupler with upward and downward grooves that extend from the upper and lower surfaces, respectively, increasing the length of the heat-transfer path and reducing the temperature gradient, thereby minimizing thermal stress. This design includes separate refrigerant flow paths for the central and outer circumferential regions, allowing independent temperature control and using a metal matrix composite material for the cooling base to enhance thermal conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single upward groove is formed in the cooling base, then the device complexity is reduced, but the thermal stress damage risk increases due to insufficient heat transfer path length

Engineering Contradiction:

Improvecooling base structureVSAvoidcoupler thermal stress resistance

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent transitions from a single upward groove to a three-dimensional groove system combining upward grooves (from top surface) and downward grooves (from bottom surface). This multi-dimensional approach extends the heat transfer path length without significantly increasing structural complexity, allowing heat to dissipate from both directions and reducing thermal stress on the coupler.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The cooling base is segmented into multiple functional zones: upward grooves for primary heat extraction, downward grooves for secondary heat extraction and thermal stress relief, and separate refrigerant flow paths for independent temperature control of central and outer circumferential regions. This segmentation enables optimized thermal management while maintaining structural integrity.

Inventive Principle:

Principle #1Segmentation

2Manufacturing precision

If separate refrigerant flow paths are formed for central and outer circumferential regions, then temperature control precision is improved, but device complexity increases

Engineering Contradiction:

Improvetemperature control precisionVSAvoidrefrigerant flow path system

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The refrigerant flow path system is segmented into a central refrigerant flow path for the central portion and an outer circumferential refrigerant flow path for the outer circumferential portion. This segmentation enables independent temperature control of different regions, allowing precise thermal management of the wafer placement surface and focus ring placement surface separately, which is critical for maintaining manufacturing precision.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The cooling base structure serves multiple functions simultaneously: it provides mechanical support, conducts heat from both upward and downward surfaces, enables separate temperature control through multiple refrigerant flow paths, and reduces thermal stress through the coupled groove system. This multi-functionality achieves precise temperature control without proportionally increasing device complexity.

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 effectively reduces damage from thermal stress, enhances handling, and maintains precise temperature control, while allowing for cost-effective manufacturing and efficient heat removal during high-power plasma processing.

Implementation Method 1

a cooling base that includes a central portion that is joined to a lower surface of the central ceramic base, an outer circumferential portion that is joined to a lower surface of the outer circumferential ceramic base

Methodology Applied

Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 2

the length of a heat-transfer path in the coupler between the central portion and the outer circumferential portion increases by that of a path in an up-down direction. Consequently, the temperature gradient of the coupler decreases, a thermal stress that is applied to the coupler is reduced

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 3

a central refrigerant flow path that is formed in the central portion and an outer circumferential refrigerant flow path that is formed in the outer circumferential portion

Methodology Applied

Scientific EffectConvection: Convection

Data Source

PatentUS12451334B2Wafer placement table

Publication Date: 2025.10.21 NGK INSULATORS LTD

AI summary

A wafer placement table includes a central ceramic base that has an upper surface including a wafer placement surface, an outer circumferential ceramic base that has an upper surface including a focus ring placement surface, and a cooling base that includes a central portion, an outer circumferential portion, and a coupler that couples the central portion and the outer circumferential portion with each other. The cooling base has a central refrigerant flow path that is formed in the central portion and an outer circumferential refrigerant flow path that is formed in the outer circumferential portion. The coupler has an upward groove that open from an upper surface and that have an annular shape, and a downward groove that opens from a lower surface, that have a ceiling surface higher than a bottom surface of the upward groove, and that have an annular shape.