Showerhead Porous Insert Reduces Backside Plasma Ignition

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Solution Overview

Problem

Existing showerhead assemblies in semiconductor processing chambers experience backside plasma ignition, leading to discoloration, polymer deposition, and contamination due to high RF electric fields, which causes bond seal erosion and particle issues.

Innovation Solution

A showerhead assembly with a porous insert located between the gas distribution plate and the base plate, which moderates corrosive radicals and reduces electrical field strength, preventing plasma ignition and contamination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If higher RF power is applied to the showerhead assembly, then processing productivity is improved, but backside plasma ignition occurs causing contamination and particle issues

Engineering Contradiction:

Improveprocessing productivityVSAvoidbackside plasma ignition and contamination

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

A porous insert material is introduced as an intermediary component between the gas distribution plate and the base plate. This insert acts as a mediator that absorbs corrosive radicals and moderates the electrical field, preventing direct harmful interactions while allowing the system to operate at higher RF powers for improved productivity

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent employs a porous insert material with specific pore structures that enable it to absorb corrosive radicals generated during plasma processing. The porous structure provides increased surface area for radical absorption and allows controlled gas flow while preventing particle generation from backside plasma ignition

Inventive Principle:

Principle #31Porous materials

2Device complexity

If the gap between gas distribution plate and base plate is reduced, then device complexity is reduced, but plasma ignition risk increases

Engineering Contradiction:

Improvedevice complexityVSAvoidplasma ignition risk

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The porous insert material is specifically designed to function in reduced gap configurations. Its porous structure allows it to effectively absorb corrosive radicals even in compact spaces, enabling reduced device complexity while maintaining reliability by preventing plasma ignition through radical absorption and field moderation

Inventive Principle:

Principle #31Porous materials

3Productivity

If the showerhead assembly is operated at higher power levels, then processing efficiency is improved, but bond seal erosion and gasket seal erosion occur

Engineering Contradiction:

Improveprocessing efficiencyVSAvoidbond seal and gasket seal integrity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The porous insert serves as a protective intermediary that absorbs corrosive radicals before they can reach and erode the bond seals and gasket seals. This mediator function allows the showerhead assembly to operate at higher power levels for improved processing efficiency while protecting the sealing components from chemical attack

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The porous insert provides beforehand cushioning by being positioned upstream in the radical transport path. It absorbs corrosive radicals in advance, creating a protective effect that prevents subsequent erosion of vulnerable components like bond seals and gasket seals during high-power operation

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 porous insert effectively reduces and eliminates backside plasma ignition, decreases particle contamination, and extends the service interval of the processing chamber by minimizing the need for cleaning, while maintaining performance at higher power levels.

Implementation Method 1

The porous insert may be a conductive material, such as metal, used to moderate the corrosive radicals resulting from plasma ignition

Methodology Applied

Scientific EffectAbsorption: Absorption (physical)

Implementation Method 2

The porous insert may be a conductive material, such as metal, used to moderate the corrosive radicals resulting from plasma ignition

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS10745807B2Showerhead with reduced backside plasma ignition

Publication Date: 2020.08.18 APPLIED MATERIALS INC

AI summary

Embodiments of the present disclosure relate to a showerhead assembly for use in a processing chamber. The showerhead assembly includes a porous insert disposed in a space defined between a gas distribution plate and a base plate to moderate the corrosive radicals resulting from plasma ignition to reduce particle issues and metal contamination in the chamber. The porous insert is a conductive material, such as metal, used to reduce the gap electrical field strength, or may be a dielectric material such as ceramic, polytetrafluoroethylene, polyamide-imide, or other materials with a low dielectric loss and high electrical field strength under conditions of high frequency and strong electric fields. As such, the electrical breakdown threshold is enhanced. The porous insert may reduce and/or eliminate showerhead backside plasma ignition and may include multiple concentric narrow rings that cover gas holes of the gas distribution plate.