Showerhead Electrode Thermal Control Plate Gasket
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Solution Overview
Problem
In semiconductor material processing, existing components within plasma chambers face challenges in withstanding thermal cycling and maintaining cleanliness and accuracy, leading to particle generation and reduced component lifespan due to galling between thermal control plates and backing members.
Innovation Solution
A showerhead electrode assembly with a thermally and electrically conductive gasket between the thermal control plate and the backing plate enhances thermal conduction and prevents galling, maintaining consistent temperature and reducing particle generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a thermal control plate is attached to the backing plate with fasteners at multiple contact points, then thermal control is improved, but galling occurs between the thermal control plate and backing plate due to thermal cycling
Solution Approach 1:
A compliant gasket material is introduced as an intermediary between the thermal control plate and backing plate. This gasket material accommodates thermal expansion and contraction during thermal cycling, preventing direct metal-to-metal contact that causes galling, while still allowing effective thermal control through the compliant interface.
Solution Approach 2:
The interface between rigid components is changed from direct rigid contact to a compliant interface. The gasket material changes the mechanical parameters of the joint, allowing for thermal movement while maintaining thermal contact, thus resolving the contradiction between thermal control and preventing galling.
2Reliability
If traditional gaskets are used between the thermal control plate and backing plate, then galling is prevented, but thermal conduction is insufficient leading to temperature shifts
Solution Approach 1:
The gasket material is selected as a composite or specially formulated material that possesses both compliant mechanical properties (to prevent galling) and high thermal conductivity (to maintain temperature stability). This composite material simultaneously addresses both requirements that traditional single-function materials could not satisfy.
Solution Approach 2:
The thermal conductivity parameter of the gasket material is optimized to be sufficiently high to maintain effective thermal conduction. By changing the material parameters from traditional low-conductivity gaskets to high-conductivity compliant materials, both reliability and temperature stability are achieved.
3Duration of action of stationary object
If components are designed to withstand thermal cycling for thousands of wafer cycles, then component lifespan is improved, but particle generation occurs due to galling and degradation
Solution Approach 1:
The compliant gasket material provides beforehand cushioning by accommodating thermal movements before they can cause galling between metal surfaces. This preventive measure reduces wear and particle generation during thermal cycling, extending component lifespan while maintaining cleanliness.
Solution Approach 2:
The gasket acts as a protective intermediary layer that prevents direct contact and galling between the thermal control plate and backing plate during thermal cycling. This intermediary prevents the degradation and particle generation that would otherwise occur at the interface during thousands of thermal cycles.
4Temperature
If multiple fasteners are used to attach the thermal control plate to the backing plate, then thermal contact is improved, but the complexity of assembly and disassembly increases
Solution Approach 1:
The compliant gasket material acts as a flexible element that can accommodate multiple contact points without requiring complex rigid fastening structures. This flexibility simplifies assembly while maintaining thermal contact across multiple points, reducing assembly complexity compared to rigid fastener systems.
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 temperature shifts and particle generation, improving the longevity and cleanliness of components, and achieving high repeatability and accuracy in semiconductor processing.
Implementation Method 1
the temperature of the showerhead electrode is controlled by the thermal control plate via enhanced thermal conduction through the at least one thermally and electrically conductive gasket
Implementation Method 2
etching a semiconductor substrate in the plasma etching chamber by applying RF power to the showerhead electrode and energizing the process gas into a plasma state
Data Source
AI summary
Showerhead electrode assemblies are disclosed, which include a showerhead electrode adapted to be mounted in an interior of a vacuum chamber; an optional backing plate attached to the showerhead electrode; a thermal control plate attached to the backing plate or to the showerhead electrode at multiple contact points across the backing plate; and at least one thermally and electrically conductive gasket separating the backing plate and the thermal control plate, or the backing plate and showerhead electrode, at the contact points. Methods of processing semiconductor substrates using the showerhead electrode assemblies are also disclosed.