The usage of the salicided resistor

[pbs681]

salicided resistor

Anybody can explain why foundries offer a salicided resistor? I don't see any advantages for the design purpose. Is it to do pre-layout simulation for parasitic poly/diff like metal resistor does?

 

[parkyuns]

resistor poly salicided

a salicided resistor can be used for the control of small resistance in the range of tenth ohms. sometimes if you want to achieve that kind of low value with metal resistance, you will use up a large area. if you use parallel of unsilicided resistors to achieve that kind of small resistance, not only the resistor will take up a large area but also parasitic caps associated with the resistors can be a problem especially when you put it for the degeneration.

 

[k_90]

poly salicided resistor

Salicide:
Standard process uses salicide for the improvement of ESD senitivity, or analog type devices. Resistors , NMOS/PMOS transistors have salicide on top of it, to decrease the RC delay of the poly silicon line. By adding salivide block you INCREASE the resisvity of that device, thus increased the amount of resistance per square.

 

[pbs681]

Salicide:
Standard process uses salicide for the improvement of ESD senitivity, or analog type devices. Resistors , NMOS/PMOS transistors have salicide on top of it, to decrease the RC delay of the poly silicon line. By adding salivide block you INCREASE the resisvity of that device, thus increased the amount of resistance per square.

Hi, thanks for your answer... but my question is why do we need salicided resistor..... we know that if we put salicided, the resistance will be lowered.... but this is resistor.... we want the resistance to be high......

 

[k_90]

Youve answered your own question there...by blocking the salicide ie taking it away you increase the resistance per square greatly allowing you to create a rpolyhigh resistor in a much smaller area. Your not adding salicide your stopping it from being placed, silicide lowers the resistance of a componment which is used over any poly device which is good for mos devices and capacitrors etc.