Well Proximity Effects

1
Well Proximity Effects

• IBM October 2006

2
Proposed new BSIM4.X Well Model Update
Proposed Basic equation
Halo adjustment term similar to Lpe0
3
To Model Asymmetry

• Redefine SCA, SCB, SCC as integrals along source
  and drain edges of Gate 3 params -gt 6 params
• Model calculates combined effect and differential
  effect.
• Model applies differential effect with sign which
  depends on whether source and drain are swapped
• Need model for Vt and conductance effect

SCAD SCBD SCCD
SCAS SCBS SCCS
Isolation
Gate
Well Edge
4
BSIM Well Proximity Changes
Should be Model parameter
Can have either sign
5
Proposal Define a not specified value

• .subckt nfet 1 2 3 4
• w0u l0u as0p
• sca1e35 scb1e35 scc1e35
• .
• .
• .
• main 1 2 3 4 nfet ww ll scasca scbscb sccscc
  

The model recognize the value 1e35 as being the
same as the parameter not being specified and the
default calculation is invoked.