PROCESS DESCRIPTION
P
ROCESS
M
ANUAL
4.3.2.4 Typicalities
The cage design is critical for the cross wafer thickness uniformity, while the injector design
and the position of the cage(s) compared to the position of the injector holes are critical for
the cross load uniformity. If the cross wafer uniformity is above 5% a new cage design is
required.
The cage(s) almost fully cover the holes of the injector. In other words, the holes are
distributed in between the first and last cage. Note that the front of the cages is leaded by 1 or
2 holes to get sufficient SiH
4
before the cages.
The O
2
and SiH
4
injectors should be aligned as indicated in the following picture:
O
2
injector
SiH
4
injector
If the gas entry mounting points are mirrored also the injector alignment should be mirrored,
the O
2
should mix in the SiH
4
stream.
For O
2
one or two extra holes are added at the door side.
If strong depletion is observed and the cross load uniformity is not improving some N
2
can
be added to the SiH
4
injector.
The pressure should be kept as low as possible while maintaining an acceptable deposition
rate. Decreasing the pressure will improve cross load uniformity some and reduce the
deposition rate.
The temperature is not an important parameter, a temperature ramp of +- 10 to 20
o
C is
typical but has limited effect.
4.3.3
Startup parameters for processing
Type Wafer
Size
[mm]
Process
Time
[min]
Pressure
[mtor]
Thickness
[Å]
Temp.
[
o
C]
SiH
4
[sccm]
O
2
[sccm]
N
2
[sccm]
TS630x 100
150
30 200 2000 425
30 90 500
TS660x 100
150
30 200 2000 425
40 120
500
TS680x 100
150
30 200 2000 425
50 150
500
TS6100x 100
150
30 200 2000 425
70 200
500
4.3.4
Recommended cleaning interval
Cleaning interval for the several components after cumulative deposition in microns on the
wafers.
Tube
Cassettes
/
baffles
SiC paddle
Trap (upstream
tubing)
Oil and filter
change
LTO
20 10 10 10 50
4.3-2
