SEMI unveils 200 mm GaAs substrate standard
The Semiconductor Equipment and Materials Institute (SEMI) has published four new technical standards relevant to the compound semiconductor community.
The SEMI M9.8 specification defines various properties for 200 mm GaAs substrates, including surface orientation, the value and tolerance for wafer diameter and thickness, the position and depth of the notch and the laser marking location.
Guidelines have also been produced for high-purity polished 50.8 mm, 76.2 mm, and 100 mm sapphire substrates that define the wafer's dimensions and crystallographic orientation. However, the documentation (SEMI M65) does not cover epiwafers and substrates that are either polished on both sides or unpolished.
The accepted method for using X-ray diffraction to determine the aluminum composition in unrelaxed and undoped AlGaAs epilayers grown on -orientated substrates is outlined in SEMI M63, while SEMI 64 describes the approved approach for using infrared absorbtion measurements to find the concentration of the deep donor EL2 in semi-insulating GaAs.
"The new specifications, which include several applicable to the emerging growth area of compound semiconductors, will help reduce the industry's manufacturing costs and speed the time to market," said Bettina Weiss, SEMI's director of international standards.
