Cooled Shadow Ring for Aluminum Film Whisker Control

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Solution Overview

Problem

In PVD chambers used for depositing thick aluminum films, the process kit shield overheats, leading to whisker growth on substrates due to inadequate cooling and thermal stress, which also affects the reflectivity of the aluminum film.

Innovation Solution

A process kit with a cooled adapter and shadow ring, featuring a heat transfer channel and ceramic insulators to enhance cooling and maintain electrical isolation, is designed to reduce the temperature of the shadow ring and improve heat transfer, thereby minimizing whisker formation and deposition non-uniformities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If significantly increased process power and deposition time are used to deposit thick aluminum films, then the aluminum film thickness is improved, but the process kit shield temperature increases causing whisker growth on substrates

Engineering Contradiction:

Improvealuminum film thicknessVSAvoidwhisker growth on substrate

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The process kit shield is segmented into multiple components including an adapter with coolant channels, a shadow ring, and a cover ring. This segmentation allows independent thermal management of each component, enabling the shield structures to be actively cooled during the deposition process to prevent whisker growth while maintaining thick aluminum film deposition

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Coolant channels are introduced as an intermediary cooling medium between the heat source (deposition process) and the process kit shield components. The coolant flows through channels in the adapter and cover ring to actively remove heat, preventing the shield temperature from rising to levels that cause whisker growth on substrates

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If the process kit shield temperature is allowed to rise during deposition, then the deposition process can proceed without active cooling, but the substrate cooling efficiency decreases and whisker formation increases

Engineering Contradiction:

Improvecooling system complexityVSAvoidsubstrate processing reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

A hydraulic cooling system using liquid coolant flowing through channels is implemented in the adapter and cover ring. This hydraulic cooling mechanism efficiently removes heat from the process kit shield components, maintaining their temperature at levels that prevent substrate overheating and whisker formation during thick aluminum film deposition

Inventive Principle:

Principle #29Pneumatics and hydraulics

3Reliability

If the shadow ring is electrically connected to the adapter, then electrical conductivity is improved, but thermal isolation is reduced leading to increased heat transfer to the substrate

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidshadow ring temperature

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

A ceramic insulator is introduced as an intermediary material between the shadow ring and the adapter. This ceramic insulator provides electrical isolation while allowing thermal management, preventing direct heat transfer from the adapter to the shadow ring while maintaining electrical discharge control during the deposition process

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 improved cooling system effectively reduces whisker formation and maintains deposition uniformity by controlling the temperature of the shadow ring and adapter, enhancing the reliability of thick aluminum film deposition processes.

Implementation Method 1

a heat transfer channel formed in the adapter body

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

a heat transfer channel formed in the adapter body

Methodology Applied

Scientific EffectConvection: Convection

Implementation Method 3

a ceramic insulator disposed between the shadow ring and the adapter to electrically isolate the shadow ring from the adapter

Methodology Applied

Scientific EffectElectrical insulation: Dielectric

Implementation Method 4

the temperature of the cover ring and shield play an important role in cooling the substrate via thermal radiation

Methodology Applied

Scientific EffectThermal radiation: Thermal Radiation

Implementation Method 5

Because the substrate is electrostatically chucked to the pedestal

Methodology Applied

Scientific EffectElectrostatic attraction: Electrostatics

Data Source

PatentUS10648071B2Process kit having a floating shadow ring

Publication Date: 2020.05.12 APPLIED MATERIALS INC

AI summary

Embodiments of process kits and process chambers incorporating same are provided herein. In some embodiments, a process kit includes an adapter having an adapter body and a shield portion radially inward of the adapter body; a heat transfer channel formed in the adapter body; a shadow ring coupled to the adapter such that the shield portion of the adapter extends over a portion of the shadow ring; and a ceramic insulator disposed between the shadow ring and the adapter to electrically isolate the shadow ring from the adapter.