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    Why first NMOS device was fabricatd nearly a decade after PMOS fabrication?

    Hi all

    What took so long that first NMOS device was fabricated after nearly a decade of PMOS fabrication?
    Since it just need to reverse the source and substrate region.

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    Re: Why first NMOS device was fabricatd nearly a decade after PMOS fabrication?

    Your assumptions are incorrect and do not reflect the complexity of process fabrication steps. THe initial fab processes did not work with n-ch depletion mode very well. They could only make p-ch dep. mode then when enhancement mode was possible, as I recall by replacing diffusion & thermal oxidation with ion implant and CVD deposition.


    This shows some history.

    http://ecee.colorado.edu/~bart/book/...ter7/ch7_6.htm
    A best design is easily achieved with good test specs™
    A better question deserves a better answer. ™
    ... so include all your acceptance criteria ( values, % tolerance) and assumptions in your question or any design.

    ... Tony Stewart EE since 1975
    - slightly north of Toronto


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