Plasma Chamber Clamp Assembly Segmentation

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Solution Overview

Problem

Existing clamp assemblies for plasma processing of thin wafers on carriers face issues such as high erosion rates, leading to short clamp lifetimes, increased cost of ownership, and reduced mean wafers between cleans and mean time between cleans, due to inadequate edge protection and RF coupling.

Innovation Solution

A clamp assembly with an outer and inner clamp member, where a gap is created between them to reduce RF coupling and erosion, with the inner clamp member acting as a sacrificial element, formed from dielectric materials like alumina, and featuring a clamping surface design that minimizes RF interaction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a thin annular clamp is used to minimize wafer edge exclusion, then wafer edge exclusion is reduced, but the erosion rate of the clamp increases

Engineering Contradiction:

Improvewafer edge exclusionVSAvoidclamp erosion rate

Core Design Contradiction:

Object-affected harmful factorsVSLoss of substance

Solution Approach 1:

The clamp assembly is divided into two separate components: an inner clamp member that contacts the wafer and an outer clamp member that provides structural support. This segmentation allows the inner clamp to be thin (reducing wafer edge exclusion) while the outer clamp provides durability and can be replaced independently.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The inner clamp member is designed as a sacrificial component that is consumable and replaceable. By making the inner clamp disposable, the system accepts its erosion and replacement, while the outer clamp remains durable and reusable, solving the erosion problem without compromising wafer edge protection.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Reliability

If a mechanical clamp provides enhanced clamping force, then wafer holding stability is improved, but RF coupling and plasma attack increase

Engineering Contradiction:

Improvewafer holding stabilityVSAvoidplasma attack and RF coupling

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The inner clamp member acts as an intermediary between the wafer and the plasma environment. It provides the necessary mechanical clamping force while being designed to withstand and sacrificially protect against plasma attack and RF coupling, preventing direct exposure of the outer clamp and support structures to these harmful factors.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The clamp assembly uses composite construction with the inner clamp member made from plasma-resistant materials (such as ceramic or specialized coatings) that can withstand plasma attack and RF coupling, while the outer clamp provides structural support. This composite approach allows the system to maintain both clamping force and resistance to plasma damage.

Inventive Principle:

Principle #40Composite materials

3Ease of manufacture

If a single piece annular clamp is used, then manufacturing simplicity is improved, but clamp lifetime is reduced due to high erosion

Engineering Contradiction:

Improveclamp manufacturing simplicityVSAvoidclamp lifetime

Core Design Contradiction:

Ease of manufactureVSDuration of action of stationary object

Solution Approach 1:

The clamp is segmented into inner and outer members that can be manufactured separately using optimized processes for each component's specific requirements, then assembled together. This maintains manufacturing simplicity while allowing each component to be designed for its specific function, extending overall clamp lifetime.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The inner clamp member is designed to be discarded after a certain period of use when it becomes eroded, while the outer clamp member is recovered and reused. This approach extends the overall system lifetime by selectively replacing only the consumable component rather than the entire clamp assembly.

Inventive Principle:

Principle #34Discarding and recovering

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 significantly reduces the erosion rate of the inner clamp member, extending its lifetime, reducing the need for frequent replacements, and maintaining process integrity by minimizing particulate generation and polymer deposition, thus enhancing the mean time between cleans and wafers processed.

Implementation Method 1

by spacing apart the inner portion of the outer clamp member from the inner clamp member, it is possible to reduce RF coupling between the inner clamp member and the support

Methodology Applied

Scientific EffectRF coupling: Electromagnetic Induction

Implementation Method 2

a clamp assembly for clamping a substrate to an outer peripheral portion of a support in a plasma processing chamber

Methodology Applied

Scientific EffectPlasma: Plasma

Data Source

PatentUS11056379B2Clamp assembly

Publication Date: 2021.07.06 SPTS TECH LTD

AI summary

A clamp assembly is for clamping an outer peripheral portion of a substrate to a support in a plasma processing chamber. An RF bias power is applied to the support during the plasma processing of the substrate. The clamp assembly includes an outer clamp member, and an inner clamp member which is received by the outer clamp member, the inner clamp member defining an aperture which exposes the substrate to the plasma processing. The outer clamp member has an inner portion terminating in an inner edge, wherein the inner portion is spaced apart from the inner clamp member.