Dummy Wafer Plasma Cleaning for Semiconductor Substrate Contamination

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Solution Overview

Problem

Semiconductor substrates are prone to contamination during plasma processing due to contaminants present in the process chamber, particularly from metal sources like sodium generated from quartz components, which can lead to cross-contamination and poor film quality.

Innovation Solution

A method involving a substrate processing apparatus that generates plasma in multiple regions, including a first plasma generating region for substrate processing and a second plasma generating region between the substrate and the susceptor, using a dummy wafer to remove contaminants like sodium from the susceptor and chamber walls, thereby preventing substrate contamination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If plasma processing is performed in a process chamber with quartz components, then substrate processing can be conducted, but metal contamination (particularly sodium) is generated from the quartz and contaminates the substrate

Engineering Contradiction:

Improvesubstrate processing capabilityVSAvoidmetal contamination

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

A dummy wafer is introduced as an intermediary substance to absorb metal contaminants (particularly sodium) from the process chamber. The dummy wafer is positioned on the susceptor and exposed to plasma, causing contaminants to transfer from the chamber walls and components to the dummy wafer instead of the product substrate, thereby protecting the substrate from contamination while maintaining the use of quartz components in the chamber

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If the susceptor is made of metal material, then substrate processing is efficient, but metal contamination is transferred directly from the susceptor to the substrate

Engineering Contradiction:

Improveprocessing efficiencyVSAvoidmetal contamination

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The dummy wafer serves as an intermediary layer between the metal susceptor and the product substrate. It absorbs metal contaminants that would otherwise transfer directly from the susceptor to the substrate during plasma processing, thereby maintaining processing efficiency while preventing contamination

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The dummy wafer is used as a consumable item that is intentionally contaminated to protect the product substrate. After absorbing contaminants, the dummy wafer is discarded or regenerated, serving as a sacrificial element that enables continuous clean processing of substrates

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Manufacturing precision

If plasma discharging power is increased to remove contaminants, then contamination removal effectiveness improves, but damage to substrate or chamber components may occur

Engineering Contradiction:

Improvecontamination removal effectivenessVSAvoidcomponent integrity

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The dummy wafer acts as a buffer that allows effective contaminant removal through plasma treatment without directly exposing the substrate or chamber components to high-power plasma that could cause damage. The dummy wafer absorbs the plasma energy and contaminants, protecting other components

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The dummy wafer is used as a sacrificial element that can withstand high-power plasma treatment intended for contaminant removal. It is deliberately subjected to aggressive plasma conditions to clean the chamber environment, while the product substrate remains protected from such harsh conditions

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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

Effectively reduces metal contamination on the substrate surfaces, ensuring better film quality and reducing the risk of cross-contamination between processing apparatuses.

Implementation Method 1

processing a first substrate supported by a first substrate support by generating plasma in a first plasma generating region in a process chamber

Methodology Applied

Scientific EffectPlasma generation: Plasma

Implementation Method 2

removing a metal substance in the process chamber by generating plasma in the first plasma generating region and a second plasma generating region disposed between the first substrate support and a back surface of a second substrate supported by a second substrate support

Methodology Applied

Scientific EffectPlasma generation: Plasma

Data Source

PatentUS9966238B2Method for manufacturing semiconductor device, substrate processing apparatus and non-transitory computer-readable recording medium

Publication Date: 2018.05.08 KOKUSAI DENKI KK

AI summary

Provided is a technique capable of suppressing a product substrate from being contaminated with a contaminant generated in a process chamber. The method includes (a) processing a substrate supported by a first substrate support by generating plasma in a first plasma generating region in a process chamber; and (b) removing a metal substance in the process chamber by generating plasma in the first plasma generating region and a second plasma generating region disposed between the first substrate support and a back surface of a substrate supported by a second substrate support.