Sidewall Sputtering for Line Edge Roughness Reduction

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Solution Overview

Problem

In the semiconductor industry, existing methods fail to effectively reduce sidewall roughness in etch layers, which can lead to device failure and yield loss as feature sizes decrease, with limited contribution from lithography and high costs associated with ion beam treatment.

Innovation Solution

A method involving the use of a processing gas to form an in situ plasma with sufficient energy for sputtering and smoothing sidewall roughness in a processing chamber, combining sidewall sputtering and deposition to etch through a patterned mask, thereby reducing line edge and line width roughness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If lithography is used to reduce line edge roughness, then manufacturing precision is improved, but the contribution is limited and cannot effectively reduce sidewall roughness

Engineering Contradiction:

Improveline edge roughnessVSAvoideffectiveness in reducing sidewall roughness

Core Design Contradiction:

Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The patent replaces lithography (optical system) with plasma treatment (physical/chemical system) to address line edge roughness. The plasma process uses ion bombardment and chemical reactions to smooth sidewalls, substituting the mechanical/optical approach with a plasma-based physical-chemical process that is more effective for sidewall roughness reduction.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the physical and chemical parameters of the plasma process, including gas composition, pressure, power, and treatment time, to optimize sidewall roughness reduction. By adjusting these parameters, the plasma process can effectively smooth sidewalls where lithography fails.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If ion beam treatment is used to reduce line edge roughness, then manufacturing precision is improved, but the cost increases significantly

Engineering Contradiction:

Improveline edge roughnessVSAvoidcost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent uses plasma treatment as a more cost-effective alternative to expensive ion beam treatment. The plasma process employs readily available process gases and standard plasma equipment, making it a cheaper, disposable-like solution compared to the costly and complex ion beam system.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent substitutes ion beam treatment (expensive mechanical system) with plasma treatment (more economical physical-chemical system). The plasma process achieves similar or better sidewall roughness reduction at lower cost by using plasma chemistry and physics instead of focused ion beams.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If feature sizes are decreased to improve device density, then productivity is improved, but sidewall roughness increases causing device failure

Engineering Contradiction:

Improvedevice densityVSAvoiddevice failure rate

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies plasma treatment as a preliminary step before etching to pre-smooth the sidewalls and prepare the surface. This preliminary action prevents roughness from developing during subsequent processing, maintaining device reliability even as feature sizes decrease and density increases.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent converts the harmful effect of plasma (potential for damage) into a beneficial effect by carefully controlling plasma parameters to smooth sidewalls rather than damage them. The plasma process, when properly tuned, transforms potential harm into the benefit of reduced sidewall roughness and improved device reliability.

Inventive Principle:

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

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 approach effectively smooths sidewall roughness, improving line edge and line width roughness, reducing device failure and yield loss, and is more cost-effective than ion beam treatment by using plasma etch and sputtering to direct ions for feature sidewall smoothing.

Implementation Method 1

forming the processing gas into an in situ plasma in the processing chamber with sufficient energy to sputter and smooth sidewall roughness of the first patterned mask

Methodology Applied

Scientific EffectSputtering: Sputtering

Implementation Method 2

combining sidewall sputtering and deposition to etch through a patterned mask

Methodology Applied

Scientific EffectPhysical Vapour Deposition: Physical Vapour Deposition

Data Source

PatentUS9852924B1Line edge roughness improvement with sidewall sputtering

Publication Date: 2017.12.26 LAM RES CORP

AI summary

A method for reducing sidewall roughness in an etch layer below a first mask with sidewall roughness in a processing chamber is provided. Sidewalls of the first mask are smoothed, comprising, flowing a processing gas into the processing chamber and forming the processing gas into an in situ plasma in the processing chamber with sufficient energy to sputter and smooth sidewall roughness of the first patterned mask. The etch layer is etched through the first patterned mask.