Composite Supporting Body for FZ Single Crystal Growth

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Solution Overview

Problem

Existing methods for supporting single crystals during the floating zone method are inadequate for producing large and heavy crystals, as they fail to distribute mechanical stress effectively, leading to potential spillover and termination of crystal growth due to vibration caused by reaction forces on crystal ridges.

Innovation Solution

A supporting body comprising a soft glass material and a hard metal or ceramic material is pressed against the conical section of the growing single crystal, allowing force distribution over a large area and preventing crystal ridge collapse, with a preferred embodiment of an outer cylindrical ring made of metal or ceramic and an inner cylindrical ring made of borosilicate glass.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a hard ring is used to support the single crystal, then the mechanical strength is improved, but the crystal ridges collapse due to concentrated pressure

Engineering Contradiction:

Improvemechanical strength of supporting bodyVSAvoidcrystal ridge collapse

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The supporting body features a soft inner ring and a hard outer ring, creating different local material properties. The soft inner ring contacts the crystal surface to distribute pressure and prevent ridge collapse, while the hard outer ring provides the necessary mechanical strength and stability for supporting heavy single crystals.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The supporting body is constructed as a composite structure with two distinct rings: an inner ring made of soft material (rubber, plastic, or fabric) and an outer ring made of hard material. This composite design combines the pressure-distributing benefits of soft materials with the structural strength of hard materials, resolving the contradiction between strength and crystal ridge protection.

Inventive Principle:

Principle #40Composite materials

2Productivity

If the single crystal diameter increases, then the production capacity is improved, but the vibration and spillover risk increase

Engineering Contradiction:

Improvesingle crystal production capacityVSAvoidvibration and melt spillover

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The soft inner ring provides localized cushioning at the contact point with the single crystal, absorbing vibrations and preventing the transmission of mechanical shocks that would cause melt spillover, while allowing the crystal diameter to increase for higher production capacity.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The soft inner ring acts as a pre-positioned cushioning element between the supporting body and the single crystal, absorbing vibrations and shocks before they can transmit to the melt and cause spillover, enabling stable growth of larger crystals.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If a glass tube supporting body is used, then the crystal growth is protected from perturbations, but the glass body breaks under increased mechanical stress

Engineering Contradiction:

Improveprotection from perturbationsVSAvoidmechanical stress resistance

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The supporting body combines a soft inner ring for vibration damping with a hard outer ring for mechanical strength, replacing the fragile single-material glass tube with a composite structure that maintains reliability while withstanding the mechanical stress of larger, heavier single crystals.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The invention changes the material parameters of the supporting body by using a composite structure with different hardness and elasticity values in the inner and outer rings, enabling the supporting body to simultaneously provide perturbation protection and mechanical strength.

Inventive Principle:

Principle #35Parameter changes

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 method effectively supports large and heavy single crystals by distributing reaction forces and preventing damage from alternating rotation, ensuring stable crystal growth and preventing melt spillover.

Implementation Method 1

pressing a supporting body against the conical section of the growing single crystal at a temperature at which a first material of the supporting body becomes soft

Methodology Applied

Scientific EffectTemperature-dependent softening:

Data Source

PatentUS10094042B2Method of supporting a growing single crystal during crystallization of the single crystal according to the FZ method

Publication Date: 2018.10.09 SILTRONIC AG

AI summary

A growing single crystal is supported in the region of a conical section of the single crystal via a supporting body during crystallization of the single crystal by the FZ method. The method comprises pressing the supporting body against the conical section of the growing single crystal at a temperature at which a first material of the supporting body becomes soft, and continuing pressing the supporting body against the conical section of the growing single crystal until the first material and a second material of the supporting body that remains hard at the cited temperature touch the conical section of the growing single crystal.