Semiconductor device manufacturing: process – Chemical etching – Combined with coating step
Reexamination Certificate
2005-09-13
2005-09-13
Goudreau, George A. (Department: 1763)
Semiconductor device manufacturing: process
Chemical etching
Combined with coating step
C438S197000, C438S217000, C438S766000, C438S775000, C438S910000, C438S918000, C438S919000
Reexamination Certificate
active
06943116
ABSTRACT:
A p-channel field-effect transistor is formed on a semiconductor substrate. The transistor has an n-doped gate electrode, a buried channel, a p-doped source and a p-doped drain. The transistor is fabricated by a procedure in which, after an implantation for defining an n-type well, an oxidation is performed to form a gate-oxide layer and n-doped polysilicon is subsequently deposited. The latter is doped with boron or boron fluoride particles either in situ or by a dedicated implantation step. In a thermal process, the boron acceptors penetrate through the oxide layer into the substrate of the n-type well, where they form a p-doped zone, which serves for counter doping and sets the threshold voltage. This results in a steep profile that permits a shallow buried channel. The control of the number particles penetrating through the oxide layer is achieved by nitriding the oxide layer in an N2O atmosphere.
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Alsmeier Johann
Faul Jürgen
Goudreau George A.
Greenberg Laurence A.
Infineon - Technologies AG
Locher Ralph E.
Stemer Werner H.
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