Page 22 - 3_Chemical industry

SCA-130-310

■ Measurement example
A total of 3 different hydrofluoric acids (0,4%)
were measured:

- Hydrofluoric acid prior to etching
(HF1)
- Hydrofluoric acid after etching (a
seemingly clean wafer (HF2))
- Hydrofluoric acid after etching (a
seemingly dirty wafer (HF3))

■ NPOC method ■ Protection and safety
Acidification: 1.5% For such measurements, comprehensive
Purging time: 3 minutes protective measures for dealing with
Injection volume: 150 µL hydrofluoric acid must be urgently observed.
Number of injections: 3 This also includes wearing protective
clothing, gloves and safety goggles.

40 After measurement, the instrument must be
30 rinsed several times with water. In addition,
Signal[mV] 20 20 injections with ultrapure water must be
carried out.
10
Nevertheless
the
syringe,
of
lifetime
combustion tube and catalyst will be
-4
0 5 1 shortening, due to HF solution.
Zeit[

Figure: Peaks of the diluted HF solution.
■ Recommended instrument/ equipment
The measurements were already stable after TOC-L CPH / CPN
two or three injections. It is advantageous to OCT-L
carry out several HF injections prior to the
actual sample measurement.

■ Results

Sample NPOC RSD
[mg/L] [%]
HF 1 2.42 4.8
HF 2 3.09 3.2
HF 3 4.38 2.1