Magnetic Lift Pin Alignment in Semiconductor Processing

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Solution Overview

Problem

Conventional substrate lift pin mechanisms in semiconductor processing apparatuses face issues such as positional misalignment due to temperature differences causing heat expansion, leading to interference with susceptor through-holes, contamination, and prolonged downtime for maintenance, as well as the risk of lift pins becoming stuck in through-holes during seasoning processes.

Innovation Solution

The implementation of a substrate supporting mechanism that includes magnetic materials to reduce contact resistance between lift pins and through-holes, using ceramic hollow columns with varying diameters and surface roughness, and suspending lift pins from the susceptor to prevent misalignment and sticking, while allowing for easy attachment and detachment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the substrate lift pin is attached on the bottom portion of the reaction chamber, then the lift pin can be moved up and down to support the susceptor, but positional misalignment occurs between the through-hole in the susceptor and the lift pin due to temperature differences causing heat expansion

Engineering Contradiction:

Improvelift pin movementVSAvoidalignment between through-hole and lift pin

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The patent changes the attachment method from mechanical attachment to magnetic attachment. The lift pin is equipped with a magnet that attracts to a magnetic plate on the reaction chamber bottom, allowing the lift pin to move freely up and down while maintaining automatic alignment with the through-hole through magnetic attraction, thus resolving the misalignment issue caused by thermal expansion

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical attachment system (screws, clips, or physical connections) with a magnetic field-based attachment system. The magnet on the lift pin interacts with the magnetic plate on the reaction chamber bottom, enabling smooth movement and automatic positioning without mechanical constraints that would cause misalignment under thermal conditions

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If the substrate lift pin is attached on the bottom portion of the reaction chamber, then the lift pin can be positioned, but replacement of the lift pin requires removing the susceptor and cooling it down to safe temperature, leading to long downtime

Engineering Contradiction:

Improvelift pin positioningVSAvoiddowntime for lift pin replacement

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent separates the lift pin from the susceptor attachment system. Instead of attaching the lift pin to the susceptor (which would require removing the susceptor for replacement), the lift pin is attached to the reaction chamber bottom through magnetic attraction. This segmentation allows the lift pin to be replaced independently without touching the susceptor, eliminating the need for cooling and reducing downtime

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The magnetic plate on the reaction chamber bottom acts as an intermediary between the lift pin and the reaction chamber structure. The magnet on the lift pin interacts with this intermediary magnetic plate, allowing the lift pin to be securely positioned during operation but easily removed and replaced without affecting the susceptor or requiring temperature cooling

Inventive Principle:

Principle #24Intermediary (Mediator)

3Manufacturing precision

If the substrate lift pin is not attached and suspended from the susceptor, then there is no positional misalignment issue, but the lift pin may be caught in the through-hole during the seasoning process

Engineering Contradiction:

Improvealignment between through-hole and lift pinVSAvoidlift pin movement freedom

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent replaces the mechanical suspension system (where the lift pin is physically hung from the susceptor) with a magnetic field-based positioning system. The magnet on the lift pin is attracted to the magnetic plate on the reaction chamber bottom, allowing the lift pin to move freely without being caught in the through-hole while maintaining automatic alignment, thus resolving the reliability issue

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 solution minimizes positional misalignment, reduces contamination, prevents lift pin sticking, and facilitates faster maintenance by reducing the time required for temperature changes and lift pin replacement, thereby enhancing the operating efficiency and reliability of semiconductor processing apparatuses.

Implementation Method 1

The implementation of a substrate supporting mechanism that utilizes magnetic materials for lift pins

Methodology Applied

Scientific EffectMagnetic attraction: Magnetism

Data Source

PatentUS7638003B2Semiconductor processing apparatus with lift pin structure

Publication Date: 2009.12.29 ASM JAPAN

AI summary

A semiconductor processing apparatus includes: a reaction chamber; a susceptor disposed in the reaction chamber for placing a substrate thereon and having through-holes in an axial direction of the susceptor; lift pins slidably disposed in the respective through-holes for lifting the substrate over the susceptor; and a means for reducing contact resistance between the lift pins and the respective through-holes.