Crucible Susceptor Grooves for Gas Venting in Czochralski Process

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Higher temperatures during the Czochralski process for producing single crystal silicon lead to gas evolution from the crucible, causing gas pockets that disrupt the crystal structure, especially in larger crucibles, due to uneven heating and the sealing of gases between the crucible and susceptor.

Innovation Solution

Incorporating grooves on the susceptor and crucible surfaces that allow for gas venting above the melt plane, with specific dimensions and shapes to prevent gas pocket formation while maintaining structural integrity, such as vertical grooves with optimal height and width on the susceptor and corresponding grooves on the crucible to direct gas upwardly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If higher temperatures are used during the Czochralski process to speed up throughput, then productivity is improved, but gas evolution from the crucible causes gas pockets that disrupt the crystal structure

Engineering Contradiction:

ImprovethroughputVSAvoidcrystal structure

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The susceptor inner surface is segmented into multiple groove features that divide the gas venting function into discrete locations. These grooves are distributed around the susceptor circumference, allowing gas to escape at multiple points rather than forming large pockets, thus maintaining crystal structure integrity while enabling high-temperature operation for improved throughput

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The grooves act as intermediary structures between the crucible outer surface and the susceptor inner surface. They provide a controlled pathway for gas evolution products to escape, mediating the interaction between the heated crucible and the susceptor to prevent direct gas pocket formation that would disrupt the crystal structure

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If higher temperatures are used to speed up melting, then productivity is improved, but gas evolution causes the melt plane to change position, affecting crystal structure

Engineering Contradiction:

Improvemelting speedVSAvoidmelt plane position

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The harmful gas evolution products are extracted from the crucible-susceptor interface through the groove features. By providing dedicated escape pathways, the gas is removed from the system before it can accumulate and push the melt plane upward, thus maintaining melt plane position stability even at higher temperatures that speed up melting

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The grooves are pre-formed on the susceptor surface before the Czochralski process begins. This preliminary structural preparation ensures that when gas evolution occurs at high temperatures, the escape pathways are already in place to immediately channel gases away, preventing melt plane displacement before it can affect crystal structure formation

Inventive Principle:

Principle #10Preliminary action

3Reliability

If the crucible is sealed against the susceptor to prevent contamination, then purity is improved, but gas evolution causes gas pockets that blow up the crucible wall

Engineering Contradiction:

Improvematerial purityVSAvoidcrucible wall stability

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The sealing between crucible and susceptor is applied locally rather than uniformly. The grooves create localized regions where gas can escape, while the surrounding areas maintain tight sealing to prevent contamination. This local differentiation allows the system to achieve both purity through sealing and wall stability through controlled gas venting

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The gas evolution, which would normally be a harmful effect causing pressure buildup and crucible deformation, is converted into a beneficial outcome by channeling it through the groove features. The gas escape pathways transform the potential harm into a controlled venting mechanism that actually strengthens the sealing by allowing pressure relief without compromising the overall crucible-susceptor seal

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

Prevents gas pocket formation, maintaining a stable melt plane and crystal structure during the silicon melting and pulling process, even at elevated temperatures, by effectively venting gases and reducing the likelihood of crucible deformation.

Implementation Method 1

gas is evolved from the outer surface of the silicon crucible below the melt plane

Methodology Applied

Scientific EffectGas evolution:

Implementation Method 2

the evolved gas blows up the crucible wall into the melt, which changes the position of the melt surface

Methodology Applied

Scientific EffectGas pressure:

Data Source

PatentUS8496752B2Method and apparatus for venting gas between a crucible and a susceptor

Publication Date: 2013.07.30 SHIN ETABU QUARTZ PRODS

AI summary

During a CZ or similar process, a silica crucible is held in a graphite or similar susceptor while being heated to above between about 1580 and 1620 degrees C. Vents or grooves formed in at least one of the outer surface of the crucible and the inner surface of the susceptor permit gasses to vent upwardly and out from between the crucible and susceptor. This permits gas evolved from the crucible as a result of the heat to be vented rather than expanding between the crucible and susceptor thereby deforming the crucible.