UV-Assisted Inductively Coupled Plasma Ignition at Lower RF Power

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Solution Overview

Problem

Conventional plasma processing tools face challenges in achieving reliable and efficient ignition of inductively coupled plasmas, particularly at higher gas pressures, due to increased RF power requirements, which can lead to arcing and surface contamination, and often result in intermittent or slow ignition.

Innovation Solution

Incorporating an ultraviolet light source that emits a beam onto the dielectric or metal surface within the plasma chamber to enhance plasma ignition, reducing the need for high RF power and improving ignition consistency by ejecting free electrons into the gas, thereby accelerating the plasma's initial exponential growth.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If higher RF power is used to achieve reliable plasma ignition at higher gas pressures, then plasma ignition reliability is improved, but arcing and surface contamination occur

Engineering Contradiction:

Improveplasma ignition reliabilityVSAvoidarcing and surface contamination

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A dielectric barrier is introduced between the inductive coupling element and the plasma chamber wall to mediate the energy transfer. This barrier enables reliable plasma ignition at lower RF power levels by preventing direct arcing while still allowing electromagnetic coupling, thus resolving the contradiction between ignition reliability and surface contamination

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the operational parameters by using lower RF power levels combined with a dielectric barrier structure. This parameter change allows plasma ignition to occur reliably without the harmful effects of high power arcing, addressing both the reliability improvement and contamination reduction

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If conventional inductive coupling is used without ultraviolet light enhancement, then device complexity is reduced, but plasma ignition speed and consistency deteriorate

Engineering Contradiction:

Improvedevice complexityVSAvoidplasma ignition speed

Core Design Contradiction:

Device complexityVSSpeed

Solution Approach 1:

Ultraviolet light is emitted onto the dielectric barrier surface before plasma ignition occurs, preliminarily generating electrons through photoemission. This preliminary action accelerates the plasma ignition process by providing initial charge carriers, thus improving ignition speed without significantly increasing overall device complexity

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention replaces part of the mechanical/electrical ignition mechanism with an optical mechanism (ultraviolet light). This substitution uses photonic energy to generate electrons, accelerating plasma formation without requiring higher RF power, thus improving ignition speed while maintaining relatively simple device architecture

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Quantity of substance

If higher RF power is applied to sustain plasma at higher gas pressures, then plasma density is improved, but ion bombardment and sputtering increase

Engineering Contradiction:

Improveplasma densityVSAvoidion bombardment and sputtering

Core Design Contradiction:

Quantity of substanceVSObject-generated harmful factors

Solution Approach 1:

The dielectric barrier serves as an intermediary that modifies the plasma generation mechanism. It enables plasma sustainment at lower RF power levels by controlling the coupling between the inductive element and plasma, thus maintaining plasma density while reducing ion bombardment energy and sputtering

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the operational parameters by operating at lower RF power levels with a dielectric barrier present. This parameter change maintains adequate plasma density for processing while significantly reducing the harmful effects of ion bombardment and sputtering on chamber surfaces

Inventive Principle:

Principle #35Parameter changes

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

This approach enables faster, more reliable plasma ignition at lower RF power levels, reduces ion bombardment and sputtering, and enhances the cleanliness and longevity of plasma processing apparatus components.

Implementation Method 1

an ultraviolet light source configured to emit an ultraviolet light beam onto a metal surface that faces an interior volume of the plasma chamber

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentUS11848204B2Enhanced ignition in inductively coupled plasmas for workpiece processing

Publication Date: 2023.12.19 BEIJING E TOWN SEMICON TECH CO LTD

AI summary

Plasma processing apparatus and associated methods are provided. In one example, a plasma processing apparatus includes a plasma chamber. The plasma processing apparatus includes a dielectric wall forming at least a portion of the plasma chamber. The plasma processing apparatus includes an inductive coupling element located proximate the dielectric wall. The plasma processing apparatus includes an ultraviolet light source configured to emit an ultraviolet light beam onto a metal surface that faces an interior volume of the plasma chamber. The plasma processing apparatus includes a controller configured to control the ultraviolet light source.