Plasma Chamber Upper Electrode Cleaning via Ammonium Hydroxide and Hydrogen Peroxide

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Solution Overview

Problem

Capacitively coupled plasma chambers experience etch rate drop and etch uniformity drift due to surface contamination and morphology changes of the electrodes, necessitating an effective cleaning methodology to enhance manufacturing yields and meet surface contamination specifications.

Innovation Solution

A cleaning method involving soaking the upper electrode in a solution of ammonium hydroxide, hydrogen peroxide, and water, followed by rinsing and wiping with deionized water, effectively removes metallic contaminants without mechanical polishing or hydrofluoric acid treatment, preserving the elastomeric joint and addressing contamination on both accessible and hidden surfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional cleaning methods (mechanical polishing or hydrofluoric acid treatment) are used, then surface contamination is removed, but electrode integrity deteriorates due to excessive wear and damage

Engineering Contradiction:

Improvesurface contamination removalVSAvoidelectrode integrity

Core Design Contradiction:

Manufacturing precisionVSStrength

Solution Approach 1:

The patent changes the chemical parameters of the cleaning solution by using a specific formulation of ammonium hydroxide (28-30 weight %), hydrogen peroxide (29-31 weight %), and water in controlled volume ratios. This chemical parameter optimization enables effective contamination removal while maintaining electrode integrity, resolving the contradiction between cleaning effectiveness and material preservation

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces mechanical polishing methods with a chemical cleaning solution approach. Instead of using mechanical forces that cause wear and damage, the solution uses chemical reactions (oxidation by hydrogen peroxide and chelation by ammonium hydroxide) to remove contaminants, thereby eliminating the mechanical damage to the electrode while achieving the desired surface cleanliness

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If extended RF operation is performed, then productivity increases, but surface contamination accumulates causing etch rate drop and uniformity drift

Engineering Contradiction:

ImproveRF operation durationVSAvoidetch rate uniformity

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent implements preliminary cleaning action by developing a cleaning solution and protocol that can be applied before contamination severely impacts etch performance. The solution of ammonium hydroxide and hydrogen peroxide is designed to prevent contamination accumulation by regularly removing metallic particles, thereby maintaining etch rate uniformity over extended RF operation periods and enabling longer productive runs between major maintenance cycles

Inventive Principle:

Principle #10Preliminary action

3Manufacturing precision

If aggressive cleaning methods are used, then contamination removal effectiveness increases, but electrode surface morphology deteriorates

Engineering Contradiction:

Improvecontamination removal effectivenessVSAvoidsurface morphology

Core Design Contradiction:

Manufacturing precisionVSShape

Solution Approach 1:

The patent carefully controls the concentration parameters of the cleaning solution (ammonium hydroxide at 28-30 weight %, hydrogen peroxide at 29-31 weight %) and their volume ratios to achieve optimal cleaning effectiveness. These precise parameter settings ensure that the chemical reaction is strong enough to remove metallic contamination but gentle enough to preserve the electrode's surface morphology, resolving the contradiction between cleaning effectiveness and surface quality

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

The method significantly reduces metal contamination on the upper electrode surfaces, as shown in elemental analysis, enhancing etch performance and maintaining electrode integrity by preventing excessive wear and damage.

Implementation Method 1

ammonium hydroxide, hydrogen peroxide and water, preferably a concentrated ammonium hydroxide water solution of 28-30 weight % on NH3 basis, hydrogen peroxide water solution of 29-31 weight %

Methodology Applied

Scientific EffectOxidation: Oxidation

Implementation Method 2

ammonium hydroxide, hydrogen peroxide and water

Methodology Applied

Scientific EffectChelation:

Data Source

PatentUS9079228B2Methodology for cleaning of surface metal contamination from an upper electrode used in a plasma chamber

Publication Date: 2015.07.14 LAM RES CORP

AI summary

A method for cleaning metallic contaminants from an upper electrode used in a plasma chamber. The method comprises a step of soaking the upper electrode in a cleaning solution of concentrated ammonium hydroxide, hydrogen peroxide and water. The cleaning solution is free of hydrofluoric acid and hydrochloric acid. The method further comprises an optional step of soaking the upper electrode in dilute nitric acid and rinsing the cleaned upper electrode.