Plasma Etching System Dielectric Window Contamination Control

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Solution Overview

Problem

Existing plasma etching systems face contamination issues in the middle region of dielectric windows due to uneven electric field distribution and sputtered contaminants, with prior cleaning methods being ineffective in this area.

Innovation Solution

The system employs flat plate electrodes centered on the dielectric window and coil electrodes in the peripheral region, along with a Faraday shielding layer, to reduce contamination and enhance cleaning efficacy by distributing the electric field uniformly and using radio frequency power to ionize cleaning gases.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If coil electrodes are used to form electric field, then etching process can be performed, but electric field is concentrated in middle region causing excessively fast etching and more sputtered contaminants in middle region of dielectric window

Engineering Contradiction:

Improveetching speedVSAvoidcontamination in middle region of dielectric window

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces flat plate electrodes specifically positioned to address the middle region contamination problem. These electrodes create a localized electric field configuration that modifies plasma distribution specifically in the middle region, making the electric field distribution non-uniform in a controlled manner to reduce sputtering and contamination in the previously affected area.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent divides the electrode system into two distinct types: coil electrodes for the peripheral region and flat plate electrodes for the middle region. This segmentation allows independent optimization of electric field distribution in different spatial zones, enabling the coil electrodes to maintain their etching effectiveness while the flat plate electrodes specifically address the contamination issue in the middle region.

Inventive Principle:

Principle #1Segmentation

2Reliability

If Faraday shielding is used to reduce plasma erosion, then chamber material erosion is reduced, but plasma can still pass through slits and contaminate dielectric window, and cleaning effect is poor in middle region

Engineering Contradiction:

Improveprotection of chamber materialVSAvoidcontamination in middle region of dielectric window

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

Inventive Principle:

Principle #3Local quality

3Productivity

If cleaning gas is injected and radio frequency power is loaded to ionize cleaning gas, then contamination particles can be removed, but cleaning effect is favorable for outer edge region and poor for middle region

Engineering Contradiction:

Improvecleaning capabilityVSAvoidcontamination in middle region of dielectric window

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The flat plate electrodes are specifically configured to generate enhanced electric field intensity in the middle region during cleaning operations. This localized field enhancement ensures that cleaning plasma is sufficiently activated and directed toward the middle region of the dielectric window, overcoming the previous deficiency where cleaning effectiveness was concentrated only in the peripheral areas.

Inventive Principle:

Principle #3Local quality

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 configuration reduces contamination in the middle region of the dielectric window, improves etching uniformity, and facilitates effective cleaning of the middle region, thereby reducing subsequent cleaning difficulties and time costs.

Implementation Method 1

plasma is accelerated under bias pressure to reach the surface of the metal material

Methodology Applied

Scientific EffectPlasma acceleration under bias pressure: Electric Field

Implementation Method 2

metal particles sputtered from the surface of the etched material

Methodology Applied

Scientific EffectSputtering: Sputtering

Implementation Method 3

radio frequency power is loaded on the top to ionize the cleaning gas to remove contamination particles

Methodology Applied

Scientific EffectIonization: Ionisation

Implementation Method 4

Use of a Faraday shielding in a plasma processing system can reduce erosion of plasma to the material of the chamber

Methodology Applied

Scientific EffectFaraday shielding: Faraday Cage

Data Source

PatentUS20220319816A1Plasma etching system

Publication Date: 2022.10.06 JIANGSU LEUVEN INSTR CO LTD

AI summary

Disclosed is a plasma etching system, comprising a reaction chamber, a base located in the reaction chamber and used for bearing a workpiece, and a dielectric window located on the reaction chamber. Flat plate type electrodes and coil electrodes are provided on the outer surface of the dielectric window; the flat plate type electrodes are located right over the base, and the coil electrodes are arranged in the peripheral regions of the flat plate type electrodes in a surrounding manner; a Faraday shielding layer is further provided between the coil electrodes and the outer surface of the dielectric window.