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Fringe Field of an asymmetrical parallel capacitor

  1. Nov 8, 2007 #1
    I have a problem bothering me for a long time. Here it is: suppose I have an asymmetrical parallel plate capacitor with one electrode much larger than the other. For example, the capacitor could be made by depositing small-area metal electrode on heavily doped wafer with 300 nm thermal oxide. Is there a way to calculate the fringe field component parallel to the SiO2 surface at the edge of the small metal electrode? A figure is attached to make the question clear. Thanks.
     

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  3. Nov 8, 2007 #2

    clem

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    The bottom electrode seems large enough to consider as an infinite plane.
    Then you could use an image electrode, so the the field would be that of a capacitor with a
    6 nm gap.
     
  4. Nov 8, 2007 #3
    Thanks. Could you please give some details on how you got the 6 nm thickness?
     
  5. Nov 9, 2007 #4

    Meir Achuz

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    Sorry. I meant 600 nm, twice the space on the picture.
     
  6. Nov 9, 2007 #5
    Sorry I am still a little bit confused. Is the field calculated with 600 nm thickness vertical or horizontal? I am interested in the horizontal fringe field.
     
  7. Nov 9, 2007 #6

    Meir Achuz

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    It's not an easy calculation, but you calculate the fringe field of a symmetric capacitor with 600 nm between the plates.
     
  8. Nov 9, 2007 #7
    Thanks, I will try that.
     
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