Graphite in Semiconductor Crystal Growing: Requirements, Grades & Sourcing
Technical overview of graphite component requirements for Czochralski (CZ) and Float Zone (FZ) silicon crystal growing furnaces — covering purity, trace metal limits, surface treatment, and traceability.
Why Graphite Purity is Critical in CZ/FZ Furnaces
Silicon crystal quality is directly affected by trace metal contamination from furnace components. Even sub-ppm levels of certain elements (Fe, Ni, Cu, V) cause deep-level defects that degrade semiconductor device performance. Graphite components in the hot zone are the primary contamination vector.
Purity Requirements by Process
| Process | Max Total Ash | Critical Elements | Typical Grade |
|---|---|---|---|
| CZ Silicon (solar) | <50 ppm | Fe, Ni, Cu <5 ppm each | TTK-8 / ISO-88 |
| CZ Silicon (semiconductor) | <10 ppm | Fe, Ni, Cu <1 ppm each | IG-110 / IG-430U |
| Float Zone Silicon | <5 ppm | All metals <0.5 ppm | IG-110 HP |
| GaAs / InP | <10 ppm | Si, Fe <1 ppm | IG-110 / ETP-10 |
Component Traceability Requirements
- Material Test Certificate (MTC) with elemental analysis per lot
- Lot traceability from graphite block to finished component
- TOYO TANSO authorised distribution chain preferred by major fabs
- Packaging: vacuum-sealed PE bags, cleanroom handling on request
Expo's Semiconductor Supply Capability
Expo Advanced Materials is an authorised TOYO TANSO partner with full MTC traceability. We supply IG-110, IG-430U, and custom-purified grades to semiconductor fabs in India, Europe, and Southeast Asia.
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