Loading ...
Sorry, an error occurred while loading the content.

28086Re: [midatlanticretro] Re: vintage SRAMs self healing

Expand Messages
  • Dan Roganti
    Nov 13, 2012
    • 0 Attachment
      This is a very interesting anomaly. I personally can't recall this
      happening before as I haven' tried this method. I would throw out the IC
      in question if it failed a memory test.
      However, this part is one of the first times they used depletion-mode N
      channel Mosfets on the die, versus enhancement mode type. The geometry
      of the mosfet incorporates a depletion mode region which isolates the
      source, drain and gate regions - this is besides the gate insulation.
      This is the main distinction over the original mosfet type making it's
      performance comparable to the bipolar Rams of that day.
      This is a highly capacitive layer within the mosfet. I wouldn't doubt a
      40yr old component with this type of process would suffer from some kind
      of leakage. I would garner a strong a suspicion that you are
      experiencing the mosfet becoming rejuvenated, to a certain degree, by
      running the test repeatedly.

      The real question is if these components remain "healed" if you leave
      this sitting in your parts bin for a few weeks and testing them again. I
      suspect the depletion region will start to deteriorate over time again.

      Dan
    • Show all 18 messages in this topic