Crystal-growth components
Hot-zone component for crystal growth
Also known as: CZ puller heaters · Graphite crucibles for SiC · Crystal-growth heat shields · PVT furnace hot zone
Graphite hot-zone parts for CZ pullers and SiC growth furnaces.
[ Technical summary ]
Silicon crystal growth (Czochralski) and SiC growth (physical vapor transport, PVT) use a graphite hot zone: heaters, crucibles or crucible supports, shields and shaped parts. The material must hold temperature in vacuum or inert atmosphere, keep geometry and limit contamination of the crystal. Grade is chosen on purity, resistivity (if the part heats) and dimensional stability; this is not the same tooling as a hardening furnace or a pressing die.
The place is a Czochralski puller or an SiC growth furnace. The application is the set of graphite hot-zone parts: heaters, crucibles or supports, shields and shaped pieces.
These parts are not heat-treatment liners and not hot-pressing dies. Selection follows purity and the thermal geometry of the growth tool, not the hardening of metal parts.
ESGRAF machines components to drawing from high-purity isostatic or extruded graphite. When chamber insulation is required, carbon felts and CFC panels are also reviewed. State equipment type, temperature, atmosphere and drawing to quote.
[ Problem it solves ]
Build or replace the hot zone of a crystal-growth tool with graphite parts that do not contaminate the ingot and that keep the thermal geometry.
Processes
- Czochralski silicon growth
- SiC growth by PVT
- Hot-zone heating and shielding
Operating conditions
- Vacuum or inert atmosphere
- Continuous high temperature
- Low contamination of the crystal
When it is suitable
- The tool grows silicon or SiC crystal in vacuum or inert atmosphere
- Graphite heaters, crucibles, shields or supports are being replaced
- A drawing, used part or hot-zone dimensions are available
- Graphite purity is a process criterion
When it may not be suitable
- The furnace treats metal parts (hardening, annealing, sintering) and does not grow crystal
- The process runs in air at high temperature
- A pressing die or a mould-release coating is what is needed
Process challenges
- Crystal contamination from graphite impurities
- Heater failure from geometry or atmosphere
- Loss of thermal uniformity when replacing parts
Advantages
- High-purity grades for vacuum
- Heaters, shields and supports machined to drawing
- Geometry copied from a used part
Limitations
- Oxidation in air at high temperature
- Grade resistivity must match the heater electrical design
- A heat-treatment furnace grade does not replace a high-purity grade without review
Selection factors
- Purity and ash content
- Resistivity if the part is a heater
- Dimensional stability of the hot zone
- Growth-tool geometry
[ Critical selection variables ]
These variables define the grade and the geometry. Actual values are confirmed against the grade datasheet.
- Process (CZ, PVT or other crystal growth)Decisive
- Required purity and allowable contaminationDecisive
- Operating temperatureDecisive
- Atmosphere (vacuum, inert)Decisive
- Part geometry and drawingDecisive
- Electrical duty if the part heatsRelevant
[ Required material properties ]
Properties that guide selection. Numerical values come from each grade's datasheet.
Critical properties
- Purity
- Thermal stability
- Thermal shock resistance
- Ash content
Secondary properties
- Dimensional stability
- Electrical resistivity
- Machinability
- Flexural strength
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[ Frequently asked questions ]
View all FAQsTechnical content reviewed by ESGRAF — Last reviewed: October 27, 2026
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