reactive ion etching

[vijayaganesh]

why reactive ion etching is necessary for fabrication process.....?and anyone clearly tell me how it cause antenna violation?

 

[erikl]

Silicon wafers get fully covered by metal, then by an isolating layer (oxide, nitride). Lithography via masks defines areas where no metal routing should stay. Reactive ion etching removes the isolating layer and the metal below. At the end of this process, just when the routing connections are "cleared", i.e. cut off from residual metal, they can be charged by the impinging ions. If their metal area is large, enough charge can be caught to generate a voltage which causes a damaging break-through of the gate oxide. If a silicon junction is connected to such a metal wire, there's no such problem due to leakage.

 

[vijayaganesh]

well i got it now,but how u say that voltage does not cause any damage to junction?

 

[erikl]

As I told above: junction leakage current is sufficient, it doesn't damage the junction. That's the reason why any junction connected to metal or poly saves these routing connections from antenna violation (i.e. the connected gate from destructive voltage break-through).

 

[dick_freebird]

Junction leakage suffices because (1) the charging rate is low
and (2) the UV / soft X-rays from the plasma generation tend
to increase diode photoconduction.

 

[vijayaganesh]

ya i m clear now thank u everyone!