| --- Tue Nov 8 2011 | 00:00 | |
| berndj | azonenberg, i don't get why *high*-k dielectrics are good for gate insulation. doesn't that increase the gate capacitance? | 17:03 |
|---|---|---|
| azonenberg | berndj: but it also decreases leakage | 17:45 |
| azonenberg | i think | 17:45 |
| azonenberg | and lets you make the dielectric thinner | 17:45 |
| azonenberg | by contrast you want low-K for ILD | 17:46 |
| azonenberg | so you dont have capacitive coupling between wires etc | 17:46 |
| azonenberg | or wire capacitance getting in the way as much | 17:46 |
| azonenberg | berndj: i think it also lets you make the gate smaller | 17:49 |
| berndj | ILD? | 17:50 |
| azonenberg | inter-layer dielectric | 17:50 |
| berndj | okay so it's more like it *happens* to have high-K, but that isn't the reason you use it for gate insulation: instead you're using it for the higher dielectric strength it also has? | 17:51 |
| azonenberg | They're the same thing | 17:51 |
| azonenberg | higher dielectric strength will increase capacitance | 17:51 |
| berndj | err, correlated, i'm sure, but not the same thing? | 17:51 |
| azonenberg | And doing a little bit of reading it seems that really thin gate dielectrics have troubles with leakage | 17:52 |
| berndj | SF6 for example wouldn't follow that correlation too well | 17:52 |
| azonenberg | So the way to compensate is to use a *thicker* dielectric | 17:52 |
| azonenberg | but use high-K to get the same capacitance | 17:52 |
| berndj | but you *don't* want capacitance in a gate, surely? | 17:53 |
| azonenberg | I think you do | 17:53 |
| azonenberg | the higher the capacitance per unit area, the more charge you can put across it and thus the lower your on resistance | 17:54 |
| berndj | this is getting confusing :( | 17:54 |
| azonenberg | Yeah | 17:54 |
| azonenberg | Transistors are something i have not studied much | 17:54 |
| azonenberg | my focus has been MEMS so far | 17:55 |
| berndj | what you said there re charge makes sense, but i thought it's the E field that inverts the polarity of the channel | 17:55 |
| azonenberg | no idea, again | 18:00 |
| azonenberg | this is something i've been meaning to study for a while | 18:00 |
| --- Wed Nov 9 2011 | 00:00 | |
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