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.
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.
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!
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!
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
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.