Susceptor Plate Design for Epitaxial Wafer Scratch Prevention

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Solution Overview

Problem

Existing epitaxial wafer growth devices face issues with scratches on the wafer's back surface due to lift pins and uneven in-surface temperature distribution caused by gaps between susceptor components, which affect the uniformity of epitaxial film growth.

Innovation Solution

A susceptor design with a counterbore part and a plate-shaped member that supports the wafer, featuring a separation space between the plate-shaped member and the susceptor main body, which reduces the gap and ensures even heat distribution by allowing surface contact for lift pins, preventing scratches and enhancing temperature uniformity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the wafer is directly supported and lifted by lift pins, then the lifting operation is simple and direct, but scratches or pin marks occur on the back surface of the wafer

Engineering Contradiction:

Improvewafer lifting operationVSAvoidscratches on wafer back surface

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a susceptor as an intermediary component between the lift pins and the wafer. The lift pins contact the susceptor rather than the wafer directly, and the susceptor in turn supports the wafer on its front surface. This mediator prevents direct contact between the lifting mechanism and the wafer, thereby avoiding scratches and pin marks on the wafer back surface while maintaining simple lifting operation.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If a placement part is accommodated in a base part to prevent scratches, then wafer back surface is protected, but gaps between components cause uneven in-surface temperature distribution

Engineering Contradiction:

Improvescratch prevention on waferVSAvoidin-surface temperature distribution uniformity

Core Design Contradiction:

Object-affected harmful factorsVSTemperature

Solution Approach 1:

The patent extracts the lifting function from the base part by introducing a separate placement part that can be independently lifted. The placement part is accommodated in the base part during growth but can be separated for lifting operations. This extraction allows the placement part to contact and support the wafer centrally, preventing scratches, while the gap between the placement part and base part is minimized to reduce thermal interference.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent applies local quality by providing wafer support specifically at the central region through the placement part, rather than uniform support across the entire wafer. The placement part contacts the central portion of the wafer back surface, providing localized protection against scratches where the lifting action occurs, while allowing the peripheral regions to maintain thermal contact with the base part for uniform temperature distribution.

Inventive Principle:

Principle #3Local quality

3Ease of operation

If gaps exist between the placement part and base part, then the placement part can be lifted independently, but heat transmission to the wafer becomes uneven causing non-uniform epitaxial film growth

Engineering Contradiction:

Improveindependent placement part liftingVSAvoidepitaxial film thickness uniformity

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The patent implements dynamics by making the placement part movable relative to the base part. The placement part can be lifted independently from the base part during wafer loading and unloading operations, providing operational flexibility. During the epitaxial growth process, the placement part is positioned close to the base part to minimize gaps, ensuring uniform heat transmission and consistent epitaxial film thickness across the wafer surface.

Inventive Principle:

Principle #15Dynamics

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 susceptor design effectively prevents scratches on the wafer's back surface and reduces unevenness in the in-surface temperature distribution, leading to more uniform epitaxial film growth.

Implementation Method 1

heat is transmitted from a heated susceptor to a wafer at the time of vapor phase growth

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

an epitaxial silicon wafer is produced by growing a single crystal silicon thin film on a silicon wafer by vapor phase growth or epitaxial growth

Methodology Applied

Scientific EffectVapor phase growth: Physical Vapour Deposition

Data Source

PatentUS11274371B2Susceptor and epitaxial growth device

Publication Date: 2022.03.15 SUMCO CORP

AI summary

Provided is a susceptor, capable of preventing occurrence of scratches on the back surface of a wafer attributable to lift pins, and reducing unevenness of the in-surface temperature distribution of the wafer. A susceptor according to one embodiment of this disclosure has a susceptor main body and a plate-shaped member, and when a wafer is conveyed, the front surface of the plate-shaped member ascended by lift pins supports the central part of the back surface of the wafer by surface contact. A separation space between the plate-shaped member and the susceptor main body, in a state in which the plate-shaped member is placed on the recessed part, enters further into the central side of the plate-shaped member, in a direction from the front surface to the back surface of the susceptor.