Fishing – trapping – and vermin destroying
Patent
1988-05-02
1990-03-13
Hearn, Brian E.
Fishing, trapping, and vermin destroying
437 34, 437 56, 437 57, 437 41, 437 27, 437 28, 437 29, 357 233, H01L 21265, H01L 2170
Patent
active
049083279
ABSTRACT:
P channel and N channel CMOS FETs (22, 24) and a process for their simultaneous fabrication with a minimal number of masking steps are disclosed. After formation of gates (30, 32) for both P channel FETs (24) and N channel FETs (22), a first N type dopant implanting step forms lightly doped drain extensions in both the P channel FETs (24) and the N channel FETs (22). A mask then protects the N channel FET area (22) while a P type dopant is implanted in source and drain regions (36) of the P channel FET (24) at a greater concentration than the prior implanted N type dopant. Another N type dopant implant occurs to both the P channel FET (24) and N channel FET (22). The N type dopant dosage used in this second N type dopant implantation step is greater than the dosage used in the first N type dopant implantation step. Another mask is used to protect the N channel FET (22) while a second P type dopant is implanted into source and drain regions of the P channel FET (24) at a greater concentration than is used in any of the previous implantation steps. Due to the high diffusion rate of the P type dopant, an annealing step drives the P type dopant so that the P channel FET (24) source and drain regions (36) reach the active transistor region underneath the gate.
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Anderson Rodney M.
Hearn Brian E.
Sharp Melvin
Sorensen Douglas A.
Texas Instruments Incorporated
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