Resistivity Disks for Crack-Free Polycrystalline Silicon Rods

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing methods for producing large-diameter polycrystalline silicon rods struggle with cracking and chipping issues at the transition between electrodes and silicon rods, leading to reduced crack-free rod length and increased production costs.

Innovation Solution

Incorporating disks made of materials with lower electrical resistivity than polycrystalline silicon above the electrodes and below the bridge of the rod pair, which helps in uniform current distribution and reduces thermal stresses, thereby minimizing cracking and chipping.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If electrodes are used to hold and heat silicon rods during deposition, then the rods can be retained and heated for deposition, but cracking and chipping occur at the transition between electrode and silicon rod

Engineering Contradiction:

Improverod stabilityVSAvoidcrack resistance

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

A disk made of material with lower electrical resistivity than polycrystalline silicon is introduced between the electrode and the silicon rod. This intermediary disk improves current distribution and reduces thermal stresses, preventing cracking and chipping at the electrode-rod transition zone while maintaining rod stability during deposition.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If large-diameter silicon rods are produced, then production capacity increases, but cracking and chipping increase as deposition diameter increases

Engineering Contradiction:

Improveproduction capacityVSAvoidcrack-free rod length

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The disk acts as an intermediary component that specifically addresses the cracking problem in large-diameter rods by improving current distribution and reducing thermal stresses at the electrode-rod interface, enabling production of large-diameter rods with increased crack-free length.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If electrodes with high current density are used to heat rods quickly, then deposition efficiency increases, but thermal stresses increase causing more cracks

Engineering Contradiction:

Improvedeposition efficiencyVSAvoidthermal stress

Core Design Contradiction:

ProductivityVSStress or pressure

Solution Approach 1:

The electrical resistivity parameter of the disk material is specifically chosen to be lower than that of polycrystalline silicon. This parameter change improves current distribution and reduces thermal stresses while maintaining efficient heating for deposition.

Inventive Principle:

Principle #35Parameter changes

4Reliability

If rod ends are cut to remove cracks, then crack-free length is achieved, but cutting losses increase production costs

Engineering Contradiction:

Improvecrack-free rod lengthVSAvoidcutting losses

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The disk is introduced during the deposition process to prevent crack formation in the first place. This preliminary preventive action eliminates the need for extensive cutting to remove cracks, thereby reducing cutting losses and improving overall yield.

Inventive Principle:

Principle #10Preliminary action

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 method significantly increases the length of crack-free and chip-free polycrystalline silicon rods, enhancing the efficiency and economic viability of the production process by maintaining rod stability and reducing cutting losses.

Implementation Method 1

one or a plurality of disks consisting of a material having a lower electrical resistivity than the polycrystalline silicon under deposition conditions are introduced above the electrodes and/or below the bridge of the rod pair

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

disks consisting of a material having a lower electrical resistivity than the polycrystalline silicon

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 3

elemental silicon is deposited from the gas phase on the surface of a thin silicon rod heated to 900 to 1200° C. In this case, the halosilanes decompose at the surface of the thin rods

Methodology Applied

Scientific EffectChemical vapor deposition: Chemical Vapour Deposition

Implementation Method 4

the halosilanes decompose at the surface of the thin rods

Methodology Applied

Scientific EffectThermal decomposition: Pyrolysis

Data Source

PatentUS9023426B2Method for producing crack-free polycrystalline silicon rods

Publication Date: 2015.05.05 WACKER CHEMIE AG

AI summary

A method for producing polycrystalline silicon rods by deposition from the gas phase on a thin rod, wherein one or a plurality of disks consisting of a material having a lower electrical resistivity than the polycrystalline silicon under deposition conditions are introduced above the electrodes and/or below the bridge of the rod pair.