PROCESS SETUP AND ACCEPTANCE
P
ROCESS
M
ANUAL
3.2-1
3.2 Process recipe startup and fine-tuning
3.2.1
Introduction
Process fine-tuning is required to reach the guaranteed process specifications and improve a current
process. Many different methods lead to the same process result and any approach is valid as long
as it satisfies the specifications. A few tips are described here that can be used as a guideline for
process fine-tuning.
3.2.2
Prerequisites
The following items are required before process fine-tuning can be started.
- a fully functional system (leaktested, profiled)
- a process recipe
- appropriate temperature recipes
3.2.3
Initial settings
The initial settings can be copied from an existing recipe if that is available. Alternatively, the
example recipes given later in this manual can be used. These recipes are based on a default system,
therefore the example recipes need to be adapted to fit the customer specific machine.
Two different process conditions occur. The atmospheric processes and the LPCVD processes.
3.2.3.1 Atmospheric process
- calculate the required gasflow to obtain a refresh interval of 3 minutes for process conditions
and 5 minutes for standby conditions. Take into account the tube volume and the gas
expansion at high temperatures. For example flows see
, and keep in mind that at
1000
o
C a gas expands 4.7x (and 3.6x at 700
o
C)
- use a flat temperature
The flat temperature is sufficient for most atmospheric processes anyway (especially (dry and wet)
oxidations). A ramped temperature can be used later to counter the expected depletion effects that
will occur in the POCl
3
deposition and diffusion process.
The reason to start of with a flat temperature is to make sure the machine is performing as
expected (and therefore
should
give a depletion effect).
Table 3-1: Initial gas flows for atmospheric processes
Tube
length
[dm]
Tube ID
[dm]
Tube
volume
[liter]
MFC setting
[slm] for
700
o
C 5 min
MFC setting
[slm] for
1000
o
C 3 min
TS430x 13
1.6
26
1.5
1.9
TS460x 18
1.6
36
2.0
2.6
TS480x 20
1.6
40
2.3
2.9
TS4100x 25 1.6 50
2.8
3.6
TS630x 13
2.12
46
2.6
3.3
TS660x 18
2.12
64
3.6
4.5
TS680x 20
2.12
71
4.0
5.0
TS6100x 25
2.12 88
5.0
6.3
TS840x 13
2.7
74
4.2
5.3
