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  1. #1
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    antenna ratio of thinox is bigger than thickox ?????

    Hi,

    I am confused by the drc antenna check. In my opinion, the antenna ratio of thick oxide transistors should be bigger than thin oxide transistors, because they are more voltage tolerant. But in my design rule, it is opposite, like this. Thinox is 5500 while thickox is only 600. Is this right?


    //================================================== =============================//
    //========= Metal 1 Antenna Design Rule Checks =========//
    //================================================== =============================//

    CONNECT MET1I Fpoly Sdi BY CONTACTI

    Diode_Met = NET AREA RATIO Sdi MET1I > 0 // Island connected to Met1
    Min_diode_Met = NET AREA Diode_Met >= 0.16 // Find real diode

    6.18.1.2.1_M1
    {
    @ Maximum ratio of cumulative total Metal [Metal 1] area to poly
    @ gate area (thinox wo/protection diode) is 5500
    NET AREA RATIO MET1I Min_diode_Met ChannelThini > 5500
    [ (AREA(MET1I)*!AREA(Min_diode_Met))/AREA(ChannelThini) ]
    RDB drc_ant_met1thin.db MET1I ChannelThini
    }

    6.18.1.2.2_M1
    {
    @ Maximum ratio of cumulative total Metal [Metal 1] area to poly
    @ gate area (thickox wo/protection diode) is 600
    NET AREA RATIO MET1I Min_diode_Met ChannelThicki > 600
    [ (AREA(MET1I)*!AREA(Min_diode_Met))/AREA(ChannelThicki) ]
    RDB drc_ant_met1thick.db MET1I ChannelThicki
    }

    6.18.2.1.1_M1
    {
    @ Maximum ratio of cumulative total Metal [Metal 1] area to poly
    @ gate area (thinox w/protection diode) = (Diode area x 460)+43000
    NET AREA RATIO MET1I Min_diode_Met ChannelThini > 43000
    [ ((AREA(MET1I)*!!AREA(Min_diode_Met))/AREA(ChannelThini))-(AREA(Min_diode_Met)*460) ]
    RDB drc_ant_met1thin_wdiode.db MET1I Min_diode_Met ChannelThini
    }

    6.18.2.1.2_M1
    {
    @ Maximum ratio of cumulative total Metal [Metal 1] area to poly
    @ gate area (thickox w/protection diode) = (Diode area x 460)+43000
    NET AREA RATIO MET1I Min_diode_Met ChannelThicki > 43000
    [ ((AREA(MET1I)*!!AREA(Min_diode_Met))/AREA(ChannelThicki))-(AREA(Min_diode_Met)*460) ]
    RDB drc_ant_met1thick_wdiode.db MET1I Min_diode_Met ChannelThicki
    }



    Thank you!

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  2. #2
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    Re: antenna ratio of thinox is bigger than thickox ?????

    Very thin oxides allow, and can take, more tunneling current
    away from the antenna source. Thick oxides may just charge
    until destructive breakdown. Of course this all depends on
    just what you mean by "thin" and "thick"... I've worked in
    technologies where the "thin" ox was 1kA and ones where
    the "thick" was 90A or so.

    It seems to me that perhaps these rules were derived from
    actual testing. How lucky you are, to be working with that
    kind of foundry. Sometimes all you get are blind assertions.


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  3. #3
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    Re: antenna ratio of thinox is bigger than thickox ?????

    Now I know why the ratio is bigger. Thank you!



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