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HW#6 Solutions
EE143, Fall 2010
Problem 1
(i) Flux arriving at a wafer distance r
F’
(cos
)
2
/r
2
Thickness deposited on wafer
F’
cos
( with
=
)
(cos
)
3
/r
2
Since cos
= (r/2)/R, therefore
thickness
r
.
(ii) Step coverage problem is due to directional flux used for deposition ( e.g. both evaporation and
sputtering). Even the spherical receiving surface will be making different angles to the wafer surface normal
with different
r
positions, we will still see step coverage effects. The step coverage morphology will vary at
different
r positions.
Problem 2
The corner profiles shown in sketches below are approximate only. The exact shape depends on the
initial roundness of the corners.
a.) After 1min:
b.) After 2min:
=500
866
5000
1000
cos 30
=866
1000
cos 60
30
2886
5000
tan 30
=
SiO
2
3386
5866
tan 30
=
2000
cos 30
=1732
2000
cos 60
1732
2886
= 6732
tan 30
SiO
2
3886
=1000
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View Full Document Problem 3
(a)
(b) For conformal deposition,
less
deposition thickness is needed to planarize high aspect ratio ( large
height /narrow width) trenches.
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This note was uploaded on 03/03/2012 for the course EECS 142 taught by Professor Ee142 during the Spring '04 term at University of California, Berkeley.
 Spring '04
 ee142
 Flux

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