Fishing – trapping – and vermin destroying
Patent
1994-11-15
1995-12-05
Chauduri, Olik
Fishing, trapping, and vermin destroying
437153, 437226, 437249, H01L 21302, H01L 21225
Patent
active
054729092
ABSTRACT:
An efficient method is proposed for the preparation of a silicon single crystal wafer for discrete semiconductor devices, such as transistors, deeply doped with a dopant on one surface, the other surface being mirror-polished. Different from the conventional process in which a single base wafer is subjected to a deposition doping and drive-in doping treatments to form a deeply doped layer on each of the surfaces followed by removal of one of the doped layers and lapping and mirror-polishing the surface, the improvement of the invention can be obtained by subjecting a base wafer having an increased thickness to the deposition and drive-in doping treatments to form deeply doped layers on both surfaces leaving an undoped layer in-between followed by slicing this base wafer by using an annular slicing blade having a thickness specifically correlated to the thickness of the starting wafer along the undoped layer into two separate wafers each having a laminar structure consisting of a doped layer and an undoped layer which are each lapped and mirror polished on the surface of the undoped layer.
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Akatsuka Takeshi
Sato Tsutomu
Chauduri Olik
Mulpuri S.
Naoetsu Electronics Company
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