Heat Shield Ring for Epitaxy Chamber Edge Uniformity

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Solution Overview

Problem

In high-growth rate epitaxy chambers, the compressed processing volume and high gas flow rates near the edge of the substrate result in insufficient residence time for process gases to absorb heat over the pre-heat ring assembly, leading to reduced growth and non-uniformity at the edge of the substrate.

Innovation Solution

A heat shield assembly comprising a heat shield member and a preheat member with a recessed portion and cutout design to enhance gas heating, ensuring adequate preheating of process gases before they reach the substrate, thereby improving uniformity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a pre-heat ring assembly is used to heat process gases, then the temperature of incoming process gases is increased, but the residence time over the pre-heat ring assembly is insufficient for high flow rates, leading to inadequate heating at the edge of the substrate

Engineering Contradiction:

Improvetemperature of process gasesVSAvoidresidence time of process gases

Core Design Contradiction:

TemperatureVSDuration of action of moving object

Solution Approach 1:

The preheat assembly is divided into two distinct functional members: a heat shield member and a preheat member. The heat shield member extends radially outward to reduce gas flow velocity, while the preheat member provides heating. This segmentation allows each component to optimize its specific function, resolving the contradiction between heating effectiveness and residence time.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The heat shield member acts as an intermediary element between the high-velocity gas flow and the preheat member. It mediates the gas flow by reducing its velocity before the gases reach the preheat member, thereby increasing residence time and allowing adequate heating to occur.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If the processing volume is compressed near the susceptor to enable high growth rate epitaxy, then production efficiency is improved, but the flow path for process gases near the edge of the substrate becomes very small, causing gases to flow at very high velocity

Engineering Contradiction:

Improvegrowth rate of epitaxial materialVSAvoidflow velocity of process gases

Core Design Contradiction:

ProductivityVSSpeed

Solution Approach 1:

The apparatus is segmented into distinct functional zones: the heat shield member handles flow velocity control, while the preheat member handles temperature control. This allows the processing volume to remain compressed for high productivity while the heat shield member locally modifies flow characteristics.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The heat shield member provides localized modification of gas flow properties. It extends radially outward at specific locations to reduce flow velocity locally, while maintaining the overall compressed processing volume structure needed for high growth rates.

Inventive Principle:

Principle #3Local quality

3Reliability

If the dome is curved at the edges where it meets the side of the chamber to confine process gases, then gas confinement is improved, but the processing volume compresses further, making the flow path near the edge extremely small and increasing gas flow velocity

Engineering Contradiction:

Improveconfinement of process gasesVSAvoidflow velocity of process gases

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The heat shield member serves as an intermediary structure between the curved dome and the substrate edge. It provides a buffer that reduces the direct impact of high-velocity flows created by the curved dome geometry, allowing the dome to maintain its gas confinement function while the heat shield member locally reduces flow velocity.

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 heat shield assembly effectively preheats process gases, increasing the temperature and residence time, which enhances epitaxial growth uniformity across the substrate by ensuring consistent gas heating at the edge of the substrate.

Implementation Method 1

The heat shield member has a reduced velocity profile for process gases flowing across the substrate

Methodology Applied

Scientific EffectFluid flow resistance: Drag

Implementation Method 2

The pre-heat ring assembly typically absorbs heat from heating elements below the susceptor and re-radiates that heat above the pre-heat ring assembly

Methodology Applied

Scientific EffectThermal radiation: Thermal Radiation

Implementation Method 3

The preheat member has a recessed portion to receive the heat shield member, creating thermal coupling

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS9879358B2Heat shield ring for high growth rate EPI chamber

Publication Date: 2018.01.30 APPLIED MATERIALS INC

AI summary

A heat shield assembly for an epitaxy chamber is described herein. The heat shield assembly has a heat shield member and a preheat member. The heat shield member is disposed on the preheat member. The heat shield member has a cutout portion that exposes a portion of the preheat member. The preheat member has a recessed portion to receive the heat shield member.