+ Post New Thread
Results 1 to 5 of 5
  1. #1
    Newbie level 2
    Points: 669, Level: 5
    praveen_k's Avatar
    Join Date
    Jun 2014
    Posts
    2
    Helped
    3 / 3
    Points
    669
    Level
    5

    why name Metal-Oxide-Semiconductor (MOSFET) even poly-Si is used?

    Hi,

    Even poly-Si replaced metal as gate in MOSFETs, why the nomenclature as Metal-Oxide-Semiconductor (MOSFET) still exists? Its now Poly-Oxide-Semiconductor. Already there's POSFET for touch sensing devices, may be this can be changed to something else. Right?

    Or is there any specific reason for why they still call it as MOSFET only?

    •   AltAdvertisement

        
       

  2. #2
    Super Moderator
    Points: 260,203, Level: 100
    Awards:
    1st Helpful Member

    Join Date
    Jan 2008
    Location
    Bochum, Germany
    Posts
    45,439
    Helped
    13824 / 13824
    Points
    260,203
    Level
    100

    Re: why name Metal-Oxide-Semiconductor (MOSFET) even poly-Si is used?

    Poly-Si acts as conductor, there's no difference in terms of device operation principles.


    1 members found this post helpful.

    •   AltAdvertisement

        
       

  3. #3
    Advanced Member level 5
    Points: 39,705, Level: 48

    Join Date
    Mar 2008
    Location
    USA
    Posts
    6,413
    Helped
    1872 / 1872
    Points
    39,705
    Level
    48

    Re: why name Metal-Oxide-Semiconductor (MOSFET) even poly-Si is used?

    Because at this point changing every bit of documentation
    ever written for a trivial distinction has value less than zero?



    •   AltAdvertisement

        
       

  4. #4
    Advanced Member level 2
    Points: 5,435, Level: 17
    Achievements:
    7 years registered

    Join Date
    Feb 2008
    Posts
    516
    Helped
    175 / 175
    Points
    5,435
    Level
    17

    Re: why name Metal-Oxide-Semiconductor (MOSFET) even poly-Si is used?

    Just to add to earlier comments -

    It's an interesting question.

    One of the main attributes of the gate is low resistivity (or high conductivity), so, theoretically, the ideal name for the structure would be conductor - oxide - semiconductor. But, in early days, metals were used as a gate material - that's why the name - MOS (metal - oxide - semiconductor), and it stayed this way, at least for historical reasons.

    "Poly", on the other hand, has many different "options" (so to speak) - low-resistivity, high-resistivity, silicided, non-silicided, etc. - so, a term "poly" itself is not associated with low resistance, required for gate material.

    By the way, in recent technologies, companies returned to using metal gates, instead of polysilicon gates (mainly to avoid polysilicon depletion effect).

    Term "oxide" is equally rather conventional - as other dielectrics can be used instead of silicon dioxide, and, in recent technologies, complex dielectric stacks, with combinations of different materials, are being used.


    1 members found this post helpful.

  5. #5
    Advanced Member level 5
    Points: 14,943, Level: 29
    schmitt trigger's Avatar
    Join Date
    Apr 2013
    Posts
    2,483
    Helped
    804 / 804
    Points
    14,943
    Level
    29

    Re: why name Metal-Oxide-Semiconductor (MOSFET) even poly-Si is used?

    People get used to certain things, and the custom persists even after it has outlived its usefulness.

    For instance, in most MS Windows software, the save icon is a floppy disk, even though floppies haven't been used in years.
    Last edited by schmitt trigger; 28th June 2014 at 02:54.



--[[ ]]--