Electrode Holder Cooling for Polysilicon Reactor Insulation

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Solution Overview

Problem

Existing apparatus for producing polycrystalline silicon using the Siemens method faces issues with thermal expansion differences between the reactor's bottom plate and electrode holders, leading to damage and deterioration of insulating materials due to inadequate cooling and heat absorption.

Innovation Solution

The apparatus incorporates an electrode holder with a cooling flow passage and an enlarged diameter portion that contacts the top face of an annular insulating material, allowing for effective heat absorption and enhanced cooling, preventing damage to the insulating material and maintaining its insulation and elasticity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the insulating material is provided between the through-holes of the bottom plate and the electrode holders, then electrical insulation is achieved, but the insulating material cannot be directly cooled and its shape is apt to be damaged due to heat in the reactor

Engineering Contradiction:

Improveinsulation functionVSAvoidheat resistance

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The electrode holder acts as an intermediary cooling structure that absorbs radiant heat and transfers it to the cooling medium circulating through its flow passage. This protects the insulating material from direct heat exposure while maintaining its insulation function, as the electrode holder is positioned between the heat source (silicon seed rod) and the insulating material

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the thermal parameter management by introducing active cooling to the electrode holder. The cooling medium circulation through the flow passage changes the temperature parameter of the electrode holder, enabling it to withstand thermal expansion differences and protect the insulating material from heat damage

Inventive Principle:

Principle #35Parameter changes

2Temperature

If a ceramic-based insulating material is used, then heat resistance is improved, but the insulating material cannot absorb the thermal expansion difference between the bottom plate and the electrode holder

Engineering Contradiction:

Improveheat resistanceVSAvoidthermal expansion absorption

Core Design Contradiction:

TemperatureVSAdaptability or versatility

Solution Approach 1:

The patent employs a composite structure combining the electrode holder (with cooling capability) and the insulating material. This composite approach allows the system to simultaneously achieve heat resistance from the insulating material and thermal expansion absorption through the flexible cooling structure of the electrode holder, which can adapt to dimensional changes

Inventive Principle:

Principle #40Composite materials

3Productivity

If the gas temperature in the reactor is elevated to 500 to 600°C for polycrystalline silicon production, then production efficiency is improved, but the electrode holders and insulating material are subjected to excessive heat

Engineering Contradiction:

Improvepolycrystalline silicon production efficiencyVSAvoidthermal load on electrode holders

Core Design Contradiction:

ProductivityVSTemperature

Solution Approach 1:

The patent extracts the heat management function from the overall system by introducing a dedicated cooling flow passage within the electrode holder. This separate cooling system allows the reactor to maintain high temperature (500-600°C) for efficient polycrystalline silicon production while the electrode holder is independently cooled, removing the thermal load from the critical components

Inventive Principle:

Principle #2Taking out (Extraction)

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 configuration effectively protects the insulating material from radiant heat, maintains its insulation and elasticity, and prevents deformation, ensuring reliable operation and increased durability of the apparatus.

Implementation Method 1

The electrode holder has a cooling flow passage formed therein for circulating a cooling medium

Methodology Applied

Scientific EffectHeat transfer: Convection

Implementation Method 2

the electrode holder absorbs the radiant heat directed to the top face

Methodology Applied

Scientific EffectRadiant heat absorption: Absorption (EM radiation)

Implementation Method 3

an electric current is applied to the silicon seed rods from the electrodes, and the silicon seed rods generate heat by the resistance thereof

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP2138459B1Apparatus for producing polycrystalline silicon

Publication Date: 2012.07.18 MITSUBISHI MATERIALS CORP

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AI summary

An apparatus for producing polycrystalline silicon which heats a silicon seed rod (4) in a reactor (1) to which a raw material gas is supplied, and deposits polycrystalline silicon on the surface of the silicon seed rod (4), includes an electrode (23) extending in a vertical direction to hold the silicon seed rod (4), an electrode holder (22) having a cooling flow passage (27) circulating a cooling medium formed therein, and inserted into a through-hole (21) formed in a bottom plate (2) of the reactor (1) to hold the electrode (23), and an annular insulating material (34) arranged between an inner peripheral surface of the through-hole (21) and an outer peripheral surface of the electrode holder (22) to electrically insulate the bottom plate (2) and the electrode holder (22) from each other.