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What is the role of SAB layer in a resistor layout?

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v.srinivas

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SAB layer

what is role of SAB layer in resistor layout, if iam not drawn what happens
 

SAB layer

SAB is the salicide block layer. The source/drain or polysilicon overlapped by SAB will not be salicided and is relatively high resistive. If you don't draw it, the resistor's resistance value will decrease dramatically.
 
Re: SAB layer

So for reliable resistance you should use salicide resistor? What is non-salicide resistor used for?

Thanks
 

Re: SAB layer

the purpose of the SAB layer is to reduce resistance. This technolgy is normally used in <0.18 tech. This is because as tech scaled down, the need of low resistance path become important because the signal getting faster.
In silicide tech all layers will be coated by silicide layer except for the layers that we don't want it to be low resistance for instance resistor structure.
 

Re: SAB layer

ccw27 said:
So for reliable resistance you should use salicide resistor? What is non-salicide resistor used for?

Thanks
Click to expand...

By placing a SAB layer, we are making the resistor without silicidation over actice areas. So placing SAB means it is a non-salicide resistor.

regards,
santhosh
 

Re: SAB layer

pbs681 said:
the purpose of the SAB layer is to reduce resistance.
Click to expand...
Just to clear this misunderstanding:
The purpose of the SAB layer is to not reduce the resistance!
The SAB layer blocks the salicide - as mentioned above - hence these salicide-blocked areas will keep their original high resistance!
 
Re: SAB layer

thanx!!!!:)


erikl said:
Just to clear this misunderstanding:
The purpose of the SAB layer is to not reduce the resistance!
The SAB layer blocks the salicide - as mentioned above - hence these salicide-blocked areas will keep their original high resistance!
Click to expand...
 

Re: SAB layer

ccw27 said:
So for reliable resistance you should use salicide resistor? What is non-salicide resistor used for?

Thanks
Click to expand...

As long as the resistor contact is silicided the unsilicided resistor is perfectly reliable so much so that unsilicided areas are a must in many ESD protection devices

pbs681 said:
the purpose of the SAB layer is to reduce resistance. This technolgy is normally used in <0.18 tech. This is because as tech scaled down, the need of low resistance path become important because the signal getting faster.
In silicide tech all layers will be coated by silicide layer except for the layers that we don't want it to be low resistance for instance resistor structure.
Click to expand...

silicide use started way before 0.18, we have an HV 0.8um process using silicide. It improves the reliability of contacts to poly and diffusion...

santhosh.mandugula said:
By placing a SAB layer, we are making the resistor without silicidation over actice areas. So placing SAB means it is a non-salicide resistor.

regards,
santhosh
Click to expand...

active area has nothing to do with silicide or silicide blocks. In this case the device is over field not over active.
 
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