Design specific variation in pattern transfer by via/contact etch ...

Bias Map
Design
� Normalized CD Bias :
Area 1-2:
Area 4:
Area 5:
Etch CD Bias Prediction
∆
n
CDBott
− CD
=
CD
Area 4
BARC.
o
BARC
. o
γ CF γ CF 2 γ CF 3
= { α0
+ α1γ
F[
1−α
2(
1−
α3D)]}[
β0
+ β1(
) + β2
( ) + β3(
) ] −1
γ γ γ
� Bias is represented in terms of CD BARC.o_predicted .
� Large bias is expected in RED regions, and could become hot
spots.
� 12x12 via blocks (area 1-2 vs. area 5) : Long range
microloading may lead to different level of bias maps
although these two patterns are locally identical.
Area 1-2 Area 5
F
Copyright ©2008, Mentor Graphics.
F
F
∆ n ≤ -0.2
∆ n = 0
∆ n ≥ 0.1