Wafers can be categorized into several types based on different classification criteria:

By Material

Silicon Wafer (Si Wafer) :The most common type, accounting for over 90% of global wafers

Compound Semiconductor Wafers:

• Gallium Arsenide Wafer (GaAs Wafer) - For high-frequency and optoelectronic applications

• Gallium Nitride Wafer (GaN Wafer) - For high-power and high-frequency devices

• Silicon Carbide Wafer (SiC Wafer) - For high-temperature and high-power devices

• Indium Phosphide Wafer (InP Wafer) - For optoelectronic devices and high-speed applications

By Diameter

Small Diameter Wafers:

• 2-inch (50mm) - Early generation, now mainly for R&D

• 3-inch (76mm) - Mostly obsolete

Mainstream Wafers:

• 4-inch (100mm) - For some special applications

• 6-inch (150mm) - Still used for some mature processes

• 8-inch (200mm) - One of current mainstream sizes

Large Diameter Wafers:

• 12-inch (300mm) - Mainstream for most advanced processes

• 18-inch (450mm) - In R&D phase, not yet in mass production

By Structure

Bulk Silicon Wafer - Traditional type

Silicon-on-Insulator Wafer (SOI Wafer) - With buried oxide layer

Epitaxial Wafer (Epi Wafer) - With epitaxial growth layer

By Doping Type

P-type Wafer

N-type Wafer

By Surface Treatment

Polished Wafer

Epitaxial Wafer

Patterned Wafer

Special Purpose Wafers

Test Wafer

Mechanical Wafer

Monitor Wafer