Wafer Cleaning Formulation for Copper Interconnects

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Semiconductor devices face reliability issues due to surface contamination and corrosion at interfaces of copper wires and low dielectric constant interlayer dielectric materials, leading to leakage, electromigration, and time-dependent dielectric breakdown, which existing cleaning solutions are unable to effectively address.

Innovation Solution

A treatment solution is developed that includes a surfactant to enhance wetting and inhibit corrosion of metallic capping layers, a complexing agent to bind and prevent redeposition of corrosion products, and a pH adjuster to maintain a pH of less than 3, ensuring effective removal of corrosion products while protecting the capping layer and maintaining compatibility with deposition solutions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional cleaning solutions are used to remove corrosion products, then cleaning effectiveness is improved, but the metallic capping layer is further corroded

Engineering Contradiction:

Improvecleaning effectivenessVSAvoidcorrosion of capping layer

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The cleaning solution uses a specific pH range (2-4) and incorporates corrosion inhibitors to modify the chemical environment, allowing effective removal of corrosion products while protecting the metallic capping layer from further corrosion

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Corrosion inhibitors act as intermediary substances that selectively protect the metallic capping layer while allowing corrosion products to be removed, serving as a mediator between the cleaning action and the metal surface

Inventive Principle:

Principle #24Intermediary (Mediator)

2Manufacturing precision

If strong cleaning agents are used to remove contamination, then manufacturing precision is improved, but device reliability deteriorates due to interface damage

Engineering Contradiction:

Improvesurface cleanlinessVSAvoidinterface integrity

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The solution uses controlled pH levels (2-4) and specific chemical compositions to achieve effective cleaning without excessive aggression that would damage the interface between copper wires and low k ILD materials

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The solution converts the potentially harmful effect of acidicsity into a beneficial cleaning mechanism while controlling the pH to prevent damage, using the acidic environment to dissolve corrosion products while the corrosion inhibitors prevent over-etching

Inventive Principle:

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

3Productivity

If wet cleaning processes are used to clean substrates, then productivity is improved, but contamination from cleaning solutions may affect deposition solution functionality

Engineering Contradiction:

Improvecleaning efficiencyVSAvoidcross-contamination

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The cleaning solution uses a specific pH range (2-4) and chemical composition that is compatible with subsequent deposition processes, minimizing the risk of contamination while maintaining effective cleaning

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The cleaning solution is designed as a single-use or limited-use formulation that performs its cleaning function and is then discarded or neutralized, avoiding the need for extensive recovery processes and minimizing residual contamination

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

The solution effectively removes corrosion products from semiconductor substrates, improving leakage current and voltage breakdown properties, and preventing redeposition, while ensuring minimal impact on the functionality of recirculated deposition solutions.

Implementation Method 1

The surfactant is configured to enhance wetting of the wafer surface

Methodology Applied

Scientific EffectSurfactant: Surfactant

Implementation Method 2

The surfactant is configured to enhance wetting of the wafer surface

Methodology Applied

Scientific EffectWetting: Wetting

Implementation Method 3

the surfactant is configured to form a self-assembled monolayer on the metallic capping layer

Methodology Applied

Scientific EffectSelf-assembly: Self-Assembly

Implementation Method 4

The complexing agent is configured to bind to corrosion product which has dissolved off of the wafer surface and into the solution

Methodology Applied

Scientific EffectComplexation:

Implementation Method 5

The pH adjusting agent may be configured to reduce the pH of the solution to approximately less than 3 during the application onto the wafer surface

Methodology Applied

Scientific EffectpH adjustment:

Data Source

PatentUS9476018B2Wafer cleaning formulation

Publication Date: 2016.10.25 LAM RES CORP

AI summary

Methods and systems for cleaning corrosion product of a metallic layer from the surface of a substrate are provided. According to one embodiment, a treatment solution includes a surfactant, a complexing agent, and a pH adjuster. The surfactant is configured to enhance wetting of the substrate surface, and inhibit further corrosion of the capping layer. The complexing agent is configured to bind to metal ions which have desorbed from the substrate surface. The pH adjuster is configured to adjust the pH to a desired level, so as to promote desorption of the corrosion product from the substrate surface.