Chapter 12: Lithography and Etching

Example 12.1 Page 406

In [1]:
#initialisation of variable
from math import *
l=.2;#mm
t=1;#time
F=30;#flow
p=350;#particles

#calculation
V=F*pi*(l/2)**2*t;#volume
N=p*V;#number

#result
print"air volume in 1min in waafer",round(V,3),"m^3"
print"number of dust particles is",round(N,0)

air volume in 1min in waafer 0.942 m^3
number of dust particles is 330.0

Example 12.2 Page 414

In [2]:
#initialisation of variable
from math import *
Et1=90;#mJ/cm^2
E11=45;#mJ/cm^2
Et2=7.0;#mJ/cm^2
E12=12.0;#mJ/cm^2

#calculation
G1=(log(Et1/E11))**-1;#gamma1
G2=(log(E12/Et2))**-1;#gamma2

#result
print"for +ve resist gamma is",round(G1,1)
print"for -ve resist gamma is",round(G2,1)

for +ve resist gamma is 1.4
for -ve resist gamma is 1.9

Example 12.3 Page 427

In [3]:
#initialisation of variable
from math import *
Ec=750.0;#centre
El=812.0;#left
Er=765.0;#right
Et=743.0;#top
Eb=798.0;#bottom
D=200.0;#diameter

#calculation
A=(Ec+El+Er+Et+Eb)/5;#average
U=(El-Et)/(El+Et)*100;#uniformity

#result
print"average etch rate is",round(A,1),"nm/min"
print"etch rate uniformity is",round(U,1),"%"

average etch rate is 773.6 nm/min
etch rate uniformity is 4.4 %

Example 12.4 Page 433

In [4]:
#initialisation of variable
from math import *
Pr=200;#pressure
Ph=5;#pressure
Na=6.02*10**23;#avagadro no.
R=.082;#rydberg's constant
T=300;#K
E1=10**9;#electron density
E2=10**10;#electron density
E3=10**11;#electron density
E4=10**12;#electron density

#calculation
#For RIE system
N1=Pr/(760000*R*T)*Na/1000;
Ie1=E1/N1;#efficiency
Ie2=E2/N1;#efficiency
#For HDP system
N2=Ph/(760000*R*T)*Na/1000;
Ie3=E3/N2;#efficiency
Ie4=E4/N2;#efficiency

#result
print"Ionization efficiency for RIE ranges from",round(Ie1,9),"to",round(Ie2,8)
print"Ionization efficiency for HDP ranges from",round(Ie3,6),"to",round(Ie4,5)

Ionization efficiency for RIE ranges from 1.55e-07 to 1.55e-06
Ionization efficiency for HDP ranges from 0.000621 to 0.00621