Silicon Ingot & Wafer Production

Silicon Ingot Formation

The monocrystalline ingots from which silicon wafers are manufactured use high-purity polysilicon as the raw material. These ingots are manufactured by a technique called the CZ (Czochralski) crystal growth process.

Polysilicon chunks are put into a quartz crucible along with boron (B) and phosphorous (P), and melted at a temperature of around 1420°C. The boron and phosphorous impurities are added in minute amounts to adjust the electrical resistance of the final wafers, determining their properties.

A monocrystalline seed crystal silicon rod is placed on the surface of the molten silicon in the crucible, and is pulled up while rotating it, to form a monocrystalline ingot having the same orientation of atoms as the seed crystal. Such an ingot is called a boule.

Quartz sand = silica sand = SiO₂

SiO₂ → Si + 2CO

Metallurical-grade silicon (MGS) at 98% pure to to solar-grade silicon (SoGS) at 99.9999% pure to electronic-grade silicon (EGS) at 99.9999%-99.999999999% (9N to 11N) pure

Poly-crystalline to mono-crystalline silicon

Czochralski Method (CZ)

quartz crucible

150mm (6in) wafer 200mm (8in) wafer 300mm (12in) wafer legacy node = 28nm and older (Chips Act) for logic

While silicon is the prevalent material for wafers used in the electronics industry, other compound III-V or II-VI materials have also been employed. Gallium arsenide (GaAs), a III-V semiconductor produced via the Czochralski method, gallium nitride (GaN) and silicon carbide (SiC) are also common wafer materials, with GaN and sapphire being extensively used in LED manufacturing.

Quartzite (silicon dioxide) Silicon smelter - 2000C: coal, charcoal, wood chips Electronic-grade polysilicon rocks quartz crucible seed crystal add dopants CZ crystal-growing vacuum furnace Wire saw - slicing Lapping, polishing, washing

Element	Symbol	State	Use

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Silicon Wafer Production

Element	Symbol	State	Use

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