Plasma Chamber Window Edge Heating for Thermal Stress Control

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Solution Overview

Problem

Plasma processing systems experience mechanical failure of windows due to large center-to-edge temperature gradients caused by high RF power and pressure, leading to stress and potential cracking or breaking, especially in larger windows used for 300 millimeter substrate processing.

Innovation Solution

A window support system with a heating element and thermal insulator member is used to maintain a consistent temperature across the window's peripheral edge, reducing heat loss and stress by introducing a heat source at the window's edge to counteract the temperature gradient.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If high RF power and pressure are used for plasma processing, then processing effectiveness is improved, but center-to-edge temperature gradient across the window increases leading to mechanical failure

Engineering Contradiction:

Improveprocessing effectivenessVSAvoidwindow mechanical integrity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies local heating to the peripheral edge region of the window by positioning the heating element to contact only the edge area. This creates a localized temperature increase at the perimeter while the center remains hot from plasma processing, thereby reducing the center-to-edge temperature gradient and preventing thermal stress-induced mechanical failure.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The heating element is activated before or during plasma processing to preemptively counteract the heat loss at the window edge. By applying heat to the peripheral region in advance or concurrently with plasma generation, the system prevents the development of excessive temperature gradients that would lead to window cracking or breaking.

Inventive Principle:

Principle #9Preliminary anti-action

2Power

If high RF power is transmitted into the chamber, then plasma generation is improved, but heat loss from the window edge increases causing large temperature gradients

Engineering Contradiction:

ImproveRF power transmissionVSAvoidheat loss from window edge

Core Design Contradiction:

PowerVSLoss of energy

Solution Approach 1:

The patent converts the harmful heat loss at the window edge into a beneficial effect by using the heating element to transform the wasted thermal energy into controlled localized heating. This compensates for the energy loss and maintains uniform temperature distribution across the window, enabling sustained high RF power operation.

Inventive Principle:

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

3Area of stationary object

If larger windows are used for 300 millimeter substrate processing, then processing capacity is improved, but temperature gradients and stress increase leading to catastrophic failure

Engineering Contradiction:

Improvewindow areaVSAvoidwindow stress resistance

Core Design Contradiction:

Area of stationary objectVSStrength

Solution Approach 1:

The heating element is specifically positioned to provide localized heating to the peripheral edge region of large-area windows. This targeted approach addresses the heightened heat loss and temperature gradient issues that are more pronounced in larger windows, thereby maintaining structural integrity and enabling the use of bigger windows for 300mm substrate processing.

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

The system effectively reduces the center-to-edge temperature gradient, maintaining window integrity during high-power/high-pressure plasma processing and minimizing the first wafer effect, thereby preventing mechanical failure and ensuring uniform processing results.

Implementation Method 1

The window support frame's top surface is configured to mechanically and thermally interface with an outer peripheral portion of the window

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

a thermal insulator member disposed on the flange portion of the adapter structure

Methodology Applied

Scientific EffectThermal insulation: Thermal Insulation

Data Source

PatentUS20250349511A1Window Edge Heater for High Power Plasma Processing Applications

Publication Date: 2025.11.13 LAM RES CORP

AI summary

A window support system for a plasma processing chamber includes a window support frame configured to circumscribe an opening. The window support frame has a top surface, a bottom surface, an inner surface, and an outer surface. Each of the inner surface and outer surface extends between the top surface and the bottom surface. A channel is formed within the outer surface. The top surface is configured to mechanically and thermally interface with an outer peripheral portion of a window that is substantially transparent to radiofrequency power. The window support system also includes a heating element disposed within the channel of the window support frame. The heating element is configured to substantially circumscribe the window support frame.