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Design >> Analog Design >> Metal gate
https://designers-guide.org/forum/YaBB.pl?num=1316707241

Message started by siddhartha .k on Sep 22^nd, 2011, 9:00am

Title: Metal gate
Post by siddhartha .k on Sep 22^nd, 2011, 9:00am

Hai
Why Pmos have metal gate why not nmos in tsmc28nm HPL Technology ? :-/

Title: Re: Metal gate
Post by raja.cedt on Sep 22^nd, 2011, 9:02am

hello,
it is very difficult to say, only foundary can say....
Thanks,
Raj.

Title: Re: Metal gate
Post by harpoon on Sep 23^rd, 2011, 9:02am

I am guessing that if both pmos and nmos gates are used, you will need 2 different types of "metal".

as a result,

it could be more complicated to qualify/stabilize the process (e.g. more variables to control) ?

or cost maybe ?

in any case ... I am also curious to know ... what does the foundry say ?

Title: Re: Metal gate
Post by raja.cedt on Sep 23^rd, 2011, 9:34am

hello harpon,
no need to use two types of metals, because of work function difference if you use same metal you will get different Vth any how it is already with normal cmos process also.

Thanks.

Title: Re: Metal gate
Post by harpoon on Sep 23^rd, 2011, 1:11pm

The different vth is the reason I am suggesting two metal, i.e. If the foundry uses metal gates on both nmos and pmos ... AND want to keep vth the same, then they need two types of metal.

So why then ... Hmmnnn ...

Title: Re: Metal gate
Post by RobG on Sep 23^rd, 2011, 3:25pm

I have no idea, but I remember reading a bit about the subject of metal gates in Spectrum. The hi-K devices need them for some reason. Click Here to get to some of the articles. Maybe the articles will jar someone's memory.

rg