Amine-Based Cleaning for Metal Cap Layers

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Solution Overview

Problem

Cleaning substrates with heterogeneous compositions, particularly those with thin film layers used in electronic device fabrication, is challenging due to corrosion and varying corrosion rates, requiring methods that avoid degradation of surface quality and thickness.

Innovation Solution

A cleaning method using a solution with an amine to maintain a pH of 7 to 13, incorporating additives like complexing agents, corrosion inhibitors, oxygen scavengers, reducing agents, and surface active agents to remove contaminants and defects from substrates with metal cap layers without significant thickness reduction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional cleaning methods are used to remove contaminants from substrates with thin film cap layers, then cleaning effectiveness is improved, but cap layer thickness is reduced and surface quality is degraded

Engineering Contradiction:

Improvecleaning effectivenessVSAvoidcap layer thickness control

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent changes the chemical parameters of the cleaning solution by specifying a pH range of 7-13 and incorporating specific additives (complexing agents, corrosion inhibitors, oxygen scavengers, reducing agents, and surface active agents) to create a controlled chemical environment that enables effective cleaning while protecting the cap layer thickness and surface quality

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The cleaning solution acts as an intermediary between the contaminants and the cap layer, using carefully selected chemical components to selectively remove contaminants while the corrosion inhibitors and other additives mediate protection of the cap layer during the cleaning process

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If aggressive cleaning solutions are used to remove contaminants and defects, then cleaning effectiveness is improved, but corrosion of metal cap layers occurs

Engineering Contradiction:

Improvecleaning effectivenessVSAvoidcorrosion damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent converts potentially harmful aggressive cleaning actions into beneficial cleaning effects by incorporating corrosion inhibitors and other protective additives that neutralize the harmful effects while maintaining the cleaning capability, effectively turning a harmful process into a protective one

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

Corrosion inhibitors and other additives in the cleaning solution act as intermediaries that protect the metal cap layers from corrosion while allowing the cleaning solution to effectively remove contaminants, bridging the conflict between cleaning effectiveness and corrosion prevention

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If cleaning solutions with low pH are used to remove contaminants, then cleaning effectiveness is improved, but metal loss and pitting occur

Engineering Contradiction:

Improvecleaning effectivenessVSAvoidmetal cap loss

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The patent changes the pH parameter from traditionally low values to a neutral or alkaline range of 7-13, fundamentally altering the cleaning mechanism to reduce metal dissolution while maintaining contaminant removal effectiveness through the synergistic action of multiple additives

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Complexing agents and corrosion inhibitors act as intermediaries that prevent metal dissolution by forming protective complexes or passive films on the metal surface, mediating between the cleaning solution and the metal cap layer to prevent metal loss while enabling effective cleaning

Inventive Principle:

Principle #24Intermediary (Mediator)

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 cleans substrates with minimal cap thickness loss, maintaining surface quality and preventing corrosion, suitable for electronic device fabrication with cobalt and nickel-based cap layers.

Implementation Method 1

cleaned with a solution comprising an amine to provide a pH for the cleaning solution of 7 to about 13

Methodology Applied

Scientific EffectpH control:

Implementation Method 2

incorporating additives like complexing agents

Methodology Applied

Scientific EffectComplexation:

Implementation Method 3

incorporating additives like complexing agents, corrosion inhibitors

Methodology Applied

Scientific EffectCorrosion inhibition:

Implementation Method 4

incorporating additives like complexing agents, corrosion inhibitors, oxygen scavengers

Methodology Applied

Scientific EffectOxygen scavenging:

Implementation Method 5

incorporating additives like complexing agents, corrosion inhibitors, oxygen scavengers, reducing agents

Methodology Applied

Scientific EffectReduction: Reduction

Implementation Method 6

incorporating additives like complexing agents, corrosion inhibitors, oxygen scavengers, reducing agents, and surface active agents

Methodology Applied

Scientific EffectSurface activity: Surfactant

Data Source

PatentUS8790465B2Post-deposition cleaning methods for substrates with cap layers

Publication Date: 2014.07.29 LAM RES CORP

AI summary

One embodiment of the present invention is a method of fabricating an integrated circuit. The method includes providing a substrate having a metal and dielectric damascene metallization layer and depositing substantially on the metal a cap. After deposition of the cap, the substrate is cleaned with a solution comprising an amine to provide a pH for the cleaning solution of 7 to about 13. Another embodiment of the presented invention is a method of cleaning substrates. Still another embodiment of the present invention is a formulation for a cleaning solution.