TTV is the difference between the maximum and minimum thickness of a silicon wafer. This parameter is an important indicator used to measure the uniformity of silicon wafer thickness. In semiconductor manufacturing, the thickness of a silicon wafer must be very uniform across the entire surface. It is usually measured at five locations on the silicon wafer and the maximum difference is calculated. Ultimately, this value is the basis for judging the quality of the silicon wafer. In practical applications, the TTV of a 4-inch silicon wafer is generally less than 2um, and that of a 6-inch silicon wafer is generally less than 3um.

Bow refers to the curvature of a silicon wafer in semiconductor manufacturing. The word may come from the description of the shape of an object when it is bent, just like the curved shape of a bow. The value of Bow is defined by measuring the maximum deviation between the center and edge of the silicon wafer. This value is usually expressed in microns (µm). The SEMI standard for 4-inch silicon wafers is Bow<40um.

Warp is a global characteristic of silicon wafers, indicating the maximum deviation of the silicon wafer surface from the plane. It measures the distance between the silicon wafer's highest and lowest point of the silicon wafer. The SEMI standard for 4-inch silicon wafers is Warp < 40um.