Electrode Assembly Cleaning for Plasma Reactor Yield

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Solution Overview

Problem

Capacitively coupled plasma reactors experience etch rate drop and etch uniformity drift due to changes in electrode surface morphology and contamination, leading to reduced manufacturing yields.

Innovation Solution

A method involving pre-cleaning with nitric acid solution, followed by ultra-pure water soaking and acidic solution treatment using hydrofluoric acid, nitric acid, and acetic acid to remove contaminants and smooth the silicon surface of the electrode assembly, ensuring surface cleanliness and roughness specifications are met.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If electrodes are used for a large number of RF hours, then productivity increases, but etch rate drop and etch uniformity drift occur due to surface contamination and morphology changes

Engineering Contradiction:

Improvenumber of RF hoursVSAvoidetch rate and etch uniformity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies preliminary action by pre-cleaning the inner liner and suspension component with nitric acid solution before placing the electrode assembly in the bath. This preventive cleaning removes potential contamination sources beforehand, ensuring that the cleaning process effectively addresses electrode surface contamination without introducing additional contaminants from the cleaning equipment itself.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent employs parameter changes by using a multi-step cleaning process with different chemical solutions (nitric acid for pre-cleaning, hydrofluoric acid for contaminant removal, and acetic acid for final treatment) and controlling their concentrations and exposure times. These parameter variations enable effective removal of different types of contamination while preserving the electrode surface morphology.

Inventive Principle:

Principle #35Parameter changes

2Object-generated harmful factors

If conventional cleaning methods are used, then some contamination is removed, but surface roughness increases and cleaning effectiveness is insufficient

Engineering Contradiction:

Improvesurface contaminationVSAvoidsurface roughness

Core Design Contradiction:

Object-generated harmful factorsVSManufacturing precision

Solution Approach 1:

The patent uses parameter changes by implementing a sequential cleaning process with three different chemical solutions, each with specific concentration ranges and exposure times. The hydrofluoric acid concentration is controlled at 0.5-5% to effectively remove contaminants while the acetic acid concentration is maintained at 5-20% for final surface treatment, optimizing both cleaning effectiveness and surface roughness control.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies composite materials by combining multiple chemical cleaning solutions (nitric acid, hydrofluoric acid, and acetic acid) in a sequential process. Each solution targets different aspects of contamination, and their combined use provides comprehensive cleaning while maintaining surface integrity, achieving better results than any single cleaning agent alone.

Inventive Principle:

Principle #40Composite materials

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 effectively removes black silicon, pits, and metallic contamination, enhancing etch performance and maintaining surface cleanliness, thereby improving manufacturing yields and maintaining surface specifications.

Implementation Method 1

pre-cleaning with nitric acid solution an inner liner of a bath and a component used to suspend the electrode assembly in the bath

Methodology Applied

Scientific EffectOxidation: Oxidation

Implementation Method 2

removing contaminants from the silicon surface by contacting the silicon surface with acidic solution comprising hydrofluoric acid, nitric acid, acetic acid, and water

Methodology Applied

Scientific EffectChemical etching:

Implementation Method 3

removing contaminants from the silicon surface by contacting the silicon surface with acidic solution

Methodology Applied

Scientific EffectDissolution:

Data Source

PatentUS7578889B2Methodology for cleaning of surface metal contamination from electrode assemblies

Publication Date: 2009.08.25 LAM RES CORP

AI summary

Systematic and effective methodology to clean capacitively coupled plasma reactor electrodes and reduce surface roughness so that the cleaned electrodes meet surface contamination specifications and manufacturing yields are enhanced. Pre-cleaning of tools used in the cleaning process helps prevent contamination of the electrode being cleaned.