Clean Bench Ionizer for Polysilicon Particle Removal

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Solution Overview

Problem

During the sorting of polycrystalline silicon in a clean bench, charged particles electrostatically adhere to the material, preventing their removal by clean air flow, which can lead to impurities in the production of single crystal silicon.

Innovation Solution

A clean bench design incorporating an ionizer to neutralize static electricity on the worktable with positively and negatively charged ions, combined with a blower and filter system to maintain high air purity and remove particles effectively, ensuring that charged particles are not adherent and can be suctioned away.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If clean air flow is used to remove particles from polycrystalline silicon, then particle removal is achieved, but charged particles electrostatically adhere to the material and cannot be removed

Engineering Contradiction:
Improveparticle removal effectivenessVSAvoidelectrostatic adhesion
Core Design Contradiction:
Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The invention introduces an ionizer that generates positive and negative ions to neutralize the static electricity on charged particles. By converting the harmful electrostatic adhesion into electrical neutrality, the particles lose their adhesive power and can be effectively removed by the clean air flow, thus transforming the harmful static electricity into a beneficial state for particle removal

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The ionizer acts as an intermediary device between the clean air flow and the charged particles. It generates ions that mediate the interaction by neutralizing the static charge on particles, enabling the clean air flow to successfully remove particles that would otherwise be stuck due to electrostatic adhesion

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If manual sorting is conducted in a clean bench, then polycrystalline silicon can be sorted by size or quality, but particles may still adhere to the material

Engineering Contradiction:
Improvemanual sorting capabilityVSAvoidmaterial purity
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The ionizer is positioned to pre-treat the polycrystalline silicon by neutralizing static electricity on particles before the manual sorting process begins. This preliminary action prevents particles from adhering to the material during subsequent handling and sorting operations, ensuring material purity is maintained throughout the manual sorting process

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

By introducing the ionizer to neutralize static charge, the invention converts the harmful effect of electrostatic adhesion into a beneficial state where particles remain loose and can be easily removed or prevented from adhering during manual sorting, thus maintaining high material purity while preserving ease of operation

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

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 solution effectively prevents particle adherence to polycrystalline silicon, maintaining the quality of single crystal silicon produced by ensuring high purity and efficient removal of static-charged particles, thus enhancing the cleanliness and quality of the final product.

Implementation Method 1

an ionizer is provided, which ionizes the clean air supplied from the supplying holes to the working space and removes static electricity on the worktable

Methodology Applied
Scientific EffectIonization: Ionisation

Implementation Method 2

suction holes are formed to the side plate of the box part, which suction air from the working space

Methodology Applied
Scientific EffectSuction: Suction

Data Source

PatentEP2036856B1Clean bench and method of producing raw material for single crystal silicon
Publication Date: 2018.09.12 MITSUBISHI MATERIALS CORP
  • EP2036856B1 patent drawingFigure 1
  • EP2036856B1 patent drawingFigure 2
  • EP2036856B1 patent drawingFigure 3~4

AI summary

A clean bench comprising a worktable on which polycrystalline silicon is placed, a box part which includes side plates to surround three sides except a front face of a working space above the worktable, and a ceiling plate which covers an upper side of the working space. Supplying holes are formed in the ceiling plate of the box part, which supply clean air onto an upper surface of the worktable. An ionizer is provided, which ionizes the clean air supplied from the supplying holes to the working space and removes static electricity on the worktable. Suction holes are formed in the side plate of the box part, which suction air from the working space.