Figure 4. Test stand for accelerated corrosion testing
normal operating process conditions. This drift
is indicative of the high level of moisture (1000
ppm) and corrosion effects in the sensor. While
1000 ppm moisture is not typically delivered
to the gas delivery components or the etch
tool, this condition simulates the cumulative
effect of a series of missteps in the fab or the
result of a leak in a system compromised by
corrosion.
Based on these results, and with the goal of
mitigating sensor drift and degradation even
in cases of extreme moisture exposure, a new
sensor design for an FRC was developed by a
manufacturer. This new FRC was made of corrosion resistant material (Ni alloy) and was tested
under aggressive corrosive conditions. Its sensor
design not only incorporates corrosion resistant
materials but improves thermal characteristics to
mitigate drift and degradation issues as well. It is
designed to withstand severely aggressive corrosive environments in a fab including significant
moisture contamination exposure.
Figure 4 shows the test stand utilized to
HBr/CI2/O2/N2 with 1:1 Flow Ratio Split
Process Recipe Baseline vs. 1000ppm Moisture (Long Exposure)
60
10 min. Exposure 20 day Exposure
Normalized Split Flows (sccm)
50
40
30
20
10
0
Q1 (sccm) Q2 (sccm)
Q3 (sccm) Q4 (sccm)
Figure 5. Effect of high moisture and, corrosive gas exposure on the new FRC
HBr/CI2 Percent Control Test Calculated sensor output change — HBr & CI2 mixed flow rate
15.0%
10.0%
Sensor Change, Rdg
5.0%
0.0%
- 5.0%
- 10.0%
100ppm 100ppm 500ppm 500ppm 1000ppm 1000ppm 1000ppm 1000ppm
Ch 1
Ch 2
Ch 3 Ni alloy
CH 4 Ni alloy
Band +
Band –
Datapoint
- 15.0%
0 5 10 15 20 25
