Glossary of Wafer Related Terms

A thin, flat substrate—typically made of silicon, sapphire, fused silica, or compound semiconductors—used as the foundational material for device fabrication.

Indicates the direction of the crystal lattice within the wafer, commonly expressed as<100>,<110>, or<111>. Crystal orientation affects mechanical strength, etching behavior, and electrical properties.

Defines whether the wafer is doped to be N-type (electron carriers) or P-type (hole carriers). Determined by dopant elements such as phosphorus, boron, or arsenic.

A measure of how strongly a material opposes electrical current, expressed in Ω·cm. Wafers are produced in a wide resistivity range depending on application needs—from highly conductive to high-resistivity substrates.

The size of the wafer measured across its circular face. Standard diameters include 2", 4", 6", 8", and 12" (50-300 mm).

The vertical dimension of the wafer, typically determined by slicing and polishing processes. Applications may require standard, thin, or ultra-thin wafers.

The allowable deviation from the specified diameter, usually within a few hundredths of a millimeter.

The difference between the maximum and minimum thickness across the wafer surface. A lower TTV indicates a more uniform wafer.

The vertical displacement of the wafer center relative to its perimeter due to internal stress. Excessive bow can affect lithography and alignment accuracy.

Measures overall non-flatness by evaluating the total deviation of the wafer surface. Critical for high-precision photolithography.

Identification marks on the edge of a wafer used to indicate orientation and conductivity type.

Flat: A straight edge segment.

Notch: A small V-shaped cut used in larger wafers.

A measure of how smooth the wafer surface is. Polished wafers typically feature extremely low surface roughness to ensure accurate device fabrication.

Describes the surface finish and flatness quality of a wafer after mechanical and chemical polishing. It determines how smooth and uniform the wafer surface is, which directly impacts device fabrication precision. Common polishing grades include:

Single-Side Polished (SSP): Only one side of the wafer is polished to a smooth finish; the other side remains as-cut.

Double-Side Polished (DSP): Both sides of the wafer are polished, offering superior flatness, uniform thickness, and minimal surface defects.

A high-quality wafer grade suitable for demanding semiconductor fabrication processes.

A lower-cost wafer used for equipment calibration, training, or non-critical testing.

A wafer with a thin, single-crystal epitaxial layer grown on top of the substrate to achieve improved electrical performance.

A specialized wafer that incorporates an insulating oxide layer between the active silicon layer and the substrate, enhancing device speed and reducing power consumption.

The number of crystalline defects per unit area. Lower defect density is essential for high-yield semiconductor manufacturing.

The process of cutting a processed wafer into individual chips or dies using a saw or laser.

A protective coating applied to the wafer surface to prevent contamination or oxidation.