Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > sci.electronics.design > #489391

Re: Power MOSET gate capacitance variations

Show all headers | View raw

Piotr Wyderski wrote...
>
> I've just measured ten MOSFETs from the same reel and their gate
> capacitance is between 1450 and 1900pF, with ~1620 being the most
> common. Since capacitance = area*permittivity/distance and the
> dielectric is the same SiO2, only area and distance (thickness) can
> vary. I don't think the manufacturer has no control over the area,
> as it is some form of litography, and thickness is proportional to
> the oxide growth time, which is exactly the same within a batch.
> So what is going on here?

 With such a high capacitance, it appears you're talking
 about a power MOSFET (it'd be nice to know the type).
 As you know, these are made with a vertical structure
 with a repeating fine-pitched laterally-stacked pattern.
 The exact height of the vertical structure is probably
 not very well controlled, and the lateral (not vertical)
 gate oxide thicknesses may also not be well controlled.
 From an Infineon note, "laterally stacked fine-pitched
 pattern of alternating arranged p- and n-areas.  The
 finer the pitch can be made, the lower the on-state
 resistance of the device will be".  Manufacturers are
 optimizing for density, not dimensional uniformity.


-- 
 Thanks,
    - Win

Back to sci.electronics.design | Previous | Next — Previous in thread | Next in thread | Find similar

Thread

Power MOSET gate capacitance variations Piotr Wyderski <peter.pan@neverland.mil> - 2017-12-25 20:40 +0100
  Re: Power MOSET gate capacitance variations Joerg <news@analogconsultants.com> - 2017-12-25 12:08 -0800
    Re: Power MOSET gate capacitance variations Cursitor Doom <curd@notformail.com> - 2017-12-25 20:33 +0000
      Re: Power MOSET gate capacitance variations Joerg <news@analogconsultants.com> - 2017-12-25 12:41 -0800
    Re: Power MOSET gate capacitance variations Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-12-25 13:57 -0700
      Re: Power MOSET gate capacitance variations amdx <nojunk@knology.net> - 2017-12-26 07:48 -0600
  Re: Power MOSET gate capacitance variations Chris Jones <lugnut808@spam.yahoo.com> - 2017-12-26 23:10 +1100
    Re: Power MOSET gate capacitance variations "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-12-26 09:35 -0600
      Re: Power MOSET gate capacitance variations Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-12-26 14:57 -0500
      Re: Power MOSET gate capacitance variations Chris Jones <lugnut808@spam.yahoo.com> - 2017-12-27 22:48 +1100
    Re: Power MOSET gate capacitance variations Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-12-26 12:58 -0500
  Re: Power MOSET gate capacitance variations Winfield Hill <hill@rowland.harvard.edu> - 2017-12-27 05:32 -0800
    Re: Power MOSET gate capacitance variations Piotr Wyderski <peter.pan@neverland.mil> - 2017-12-27 16:15 +0100
      Re: Power MOSET gate capacitance variations Winfield Hill <hill@rowland.harvard.edu> - 2017-12-27 08:47 -0800
        Re: Power MOSET gate capacitance variations "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-12-27 11:47 -0600
        Re: Power MOSET gate capacitance variations Piotr Wyderski <peter.pan@neverland.mil> - 2017-12-31 11:06 +0100
          Re: Power MOSET gate capacitance variations "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-12-31 10:43 -0600
          Re: Power MOSET gate capacitance variations Winfield Hill <hill@rowland.harvard.edu> - 2017-12-31 10:32 -0800

csiph-web