Silicon wafers must meet stringent specifications.
Silicon, an abundant element in nature, is gray and non-metallic, with a special characteristic: the ability to conduct electricity within strict controls. This feature makes it the perfect element to be used in making semiconductor wafers for computers, as there must be stringent specifications for silicon wafers to perform the required task of being the brains of a computer.
Mechanical
According to Siliconfareat, there are several mechanical specifications for wafers, such as the thickness, diameter and thickness variation. Wafers must be uniform, with little room for error or deviation. Other similar specifications relate to the flatness and the edge, bow and warp, again seeking uniformity. The wafer must also be free of markings from the manufacturing process.
Particles
Wafers must be, to the extent possible, particle-free, as outlined in ProcessSpecialties, utilizing systems to search for even the smallest particle on a highly polished wafer. Calibration is based upon a traceable particle standard, which is required when viewing the wafers.
Grades
According to Advantivtech, there are several grades of wafers, with those larger than 150 mm being divided into mechanical test and process test varieties. Mechanical test wafers are used in testing equipment, emphasizing dimensional and structural characteristics, while process test wafers, also known as monitor wafers, are used for process monitoring and some semiconductor fabrication, in addition to judging equipment cleanliness. Other grades of wafers include particle grade, designed for use in particle measurements.
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