What is EPSROX (Er: Gate Dielectric constant) in BSIM3v3?

[Alex Liao]

Hi,

I found Er = 3.9 in BSIM4.5 manual and used in calculation of Cox.
But there is no information of Er in BSIM3v3 which is used in .18um technology.

1. Is Er technology-independent which means it holds for 3.9 for all technologies?
2. If there is no such parameter in old version, how do people calculate Cox(Coxe or Coxp)?

Thanks,

 

[erikl]

1. Is Er technology-independent which means it holds for 3.9 for all technologies?

Nearly ;-). It's the physical dielectric coefficient of SiO₂ , i.e. as long as you stay with this dielectric, it is independent of structure size or BSIM versions. Other dielectrics like Si₃N₄ or Al₂O₃ (or even high-k dielectrics like HfO₂ or TiO₂) have considerably higher ε_r's.

2. If there is no such parameter in old version, how do people calculate Cox(Coxe or Coxp)?

These are extracted parameters (extracted via measurements on silicon). C_oxp is the capacity resulting from real physical thickness of the oxide, C_oxe is the capacity used for (electrical) SPICE calculations, which considers additional interface effects (fixed interstate charges).

 

[Alex Liao]

Thank you, Erikl.

Got it!