Backside Purging and Vacuum Clamping for ALD Edge Thickness Control

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Solution Overview

Problem

Substrate processing systems face challenges in reducing backside film deposition and mitigating thickness changes at substrate edges during film deposition, particularly in atomic layer deposition (ALD) processes, where deposition occurs along the backside edge of the substrate, causing defocusing issues in subsequent lithography steps and thickness variations.

Innovation Solution

A substrate processing system that employs a backside purging system using reactant gases like molecular oxygen, nitrous oxide, molecular nitrogen, or ammonia to purge the backside edge of the substrate during ALD, combined with vacuum clamping to prevent substrate movement, effectively reducing backside deposition and thickness variations by using higher flow rates safely.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If purge gas is directed at the backside edge of the substrate to reduce backside deposition, then backside deposition is reduced, but substrate movement may occur due to gas flow pressure

Engineering Contradiction:

Improvebackside deposition controlVSAvoidsubstrate movement

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The vacuum clamping system applies a counteracting force (vacuum pressure) to the substrate to counterbalance the harmful effect of gas flow pressure that causes substrate movement. This allows high flow rates to be used for effective backside purging without causing substrate displacement.

Inventive Principle:

Principle #8Anti-weight (Counterweight)

Solution Approach 2:

The system changes the operational parameters by using higher gas flow rates than previously possible, enabled by the vacuum clamping system. This parameter change (increased flow rate) directly improves the effectiveness of backside deposition reduction.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If higher flow rates are used to purge the backside edge more effectively, then backside deposition is reduced more effectively, but substrate movement increases

Engineering Contradiction:

Improvebackside deposition reductionVSAvoidsubstrate movement

Core Design Contradiction:

Manufacturing precisionVSSpeed

Solution Approach 1:

The vacuum clamping system provides a counteracting force that balances the substrate against the momentum of high-velocity gas flow. This enables the system to use higher flow rates (improving backside deposition control) without the substrate being moved by the gas pressure.

Inventive Principle:

Principle #8Anti-weight (Counterweight)

3Stability of the object's composition

If vacuum clamping is applied to prevent substrate movement, then substrate stability is improved, but the system complexity increases

Engineering Contradiction:

Improvesubstrate stabilityVSAvoidclamping system complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The vacuum clamping system acts as an intermediary mechanism between the substrate and the gas delivery system. It provides a simple yet effective means of substrate stabilization that enables the beneficial effects of high-flow backside purging without the complexity of more sophisticated substrate positioning or restraint mechanisms.

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 system significantly reduces backside deposition below acceptable levels, eliminates parasitic power loss, and prevents thickness variations at the edge of the substrate, improving the precision and accuracy of film deposition.

Implementation Method 1

The clamping system includes a vacuum clamping system to clamp the substrate to the substrate support using vacuum pressure

Methodology Applied

Scientific EffectVacuum pressure: Vacuum

Implementation Method 2

A plasma generator is configured to selectively generate RF plasma in the reaction volume

Methodology Applied

Scientific EffectRF plasma: Plasma

Implementation Method 3

During atomic layer deposition (ALD), one or more ALD cycles are performed to deposit film on the substrate

Methodology Applied

Scientific EffectAtomic layer deposition: Chemical Vapour Deposition

Implementation Method 4

A backside purging system is configured to supply a reactant gas to a backside edge of the substrate to purge the backside edge during the deposition of the film

Methodology Applied

Scientific EffectGas flow purging: Convection

Data Source

PatentUS9852901B2Systems and methods for reducing backside deposition and mitigating thickness changes at substrate edges

Publication Date: 2017.12.26 LAM RES CORP

AI summary

A substrate processing system for depositing film on a substrate includes a processing chamber defining a reaction volume and including a substrate support for supporting the substrate. A gas delivery system is configured to introduce process gas into the reaction volume of the processing chamber. A plasma generator is configured to selectively generate RF plasma in the reaction volume. A clamping system is configured to clamp the substrate to the substrate support during deposition of the film. A backside purging system is configured to supply a reactant gas to a backside edge of the substrate to purge the backside edge during the deposition of the film.