O2 Analyzer
Zirconia analyzers that measure trace oxygen in nitrogen — from ppm to percent — so diffusion and other inert-gas processes stay free of unwanted oxide.
Overview · Diffusion
Trace oxygen, measured in real time
In the diffusion process, wafers are heated in a nitrogen atmosphere. A few ppm of oxygen is enough to grow unwanted oxide, so the O2 concentration in the N2 is monitored continuously.
An O2 analyzer draws a sample of the process gas across a heated zirconia sensor and reports the concentration from ppm levels up to percent, with analog outputs and alarms for the tool or the facility monitoring system.
- Process
- Diffusion · N2 purge
- Measures
- O2 concentration in N2
- Range
- 0–10 ppm ~ 0–100 %
- Repeatability
- ±1 % F.S.
How it works
Zirconia ceramic becomes an oxygen-ion conductor when heated — the basis of a fast, stable measurement down to ppm levels.
- 01
Sample
A pump or ejector draws process gas through the analyzer at a steady flow — 0.5 L/min on the TF series.
- 02
Sense
A heated zirconia element conducts oxygen ions. The analyzer turns the oxygen partial-pressure difference, or the ion-pumping current, into O2 concentration.
- 03
Report
Readings go to the display, a 4–20 mA or voltage output and RS-232C, with upper and lower concentration alarms.
- 04
Calibrate
Air-point calibration keeps readings accurate; low ppm ranges also use a standard calibration gas.
Applications
Wherever a process depends on an oxygen-free atmosphere.
- Diffusion & oxidation furnacesConfirms the N2 atmosphere is free of oxygen before and during high-temperature steps.
- N2 purge & load locksVerifies that purging is complete so wafers are not exposed to oxygen.
- Annealing & reflowMonitors low-oxygen atmospheres where oxidation would degrade films or joints.
- Inert gas supplyChecks the O2 content of nitrogen and other inert gases at the point of use.
Models
NGK SH-200 and TF series specifications. Tell us your gas, range and output and we’ll help you choose.
| Item | SH-201-A | SH-201-B | SH-201-C |
|---|---|---|---|
| Sampling system | Ejector suction system | Pump suction system | Pump suction system |
| Setting range | 0–500 ppm ~ 0–50 % | 0–1000 ppm ~ 0–20 % | 0–100 ppm ~ 0–25 % |
| Calibration function | Air 1-point calibration (standard gas calibration is required for the 0–100 ppm range) | Air 1-point calibration (standard gas not required) | Air 1-point calibration (standard gas calibration is required for the 0–100 ppm range) |
| Linearity | ±2 %FS | ||
| Repeatability | ±1 %FS | ||
| Drift | ±2 %FS / week | ||
| Response time | Within 30 s | ||
| Warm-up time | 3 min | ||
| Power voltage | 100 V AC | 200 V AC | 100 V AC |
| Item | TF-21D201 | TF-30D201 |
|---|---|---|
| Sensor | TF-21D201 | TF-30 |
| Receiver | DFT-201 | |
| Measurement principle | Zirconia concentration cell system | Zirconia 2-cell pump critical current system |
| Measuring ranges | Min. 0–10 ppm ~ max. 0–100 % 4 freely selected ranges (zero point fixed) | Min. 0–10 ppm ~ max. 0–100 % 4 freely selected ranges Note: cannot measure 25 % O2 or greater |
| Scope of measurement | 0 – Air | |
| Calibration | Air point calibration, max. 4 points | Air point + max. 3-point calibration by calibration gas Air 1-point calibration (0–1000 ppm or greater) Calibration by data input (0–1000 ppm or greater, when the sensor is exchanged) |
| Output | 1 point 4–20 mA (non-isolated, load resistance < 600 Ω) 1 point 0–1 V, 0–5 V or 0–10 V (non-isolated) | 1 point 4–20 mA (non-isolated, load resistance < 600 Ω) 1 point 0–1 V, 0–5 V or 0–10 V (non-isolated) |
| Sample / calibration gas flow | 0.5 ± 0.02 L/min | 0.5 ± 0.1 L/min |
| Reproducibility | ±1 % F.S. | ±1 % F.S. (0–25 % fixed range: ±0.5 % F.S.) |
| Linearity | Over 0–100 ppm: ±2 % F.S. Under 0–100 ppm: ±3 % F.S. | ±2 % F.S. (0–25 % fixed range: ±1.0 % F.S.) |
| Response time (90 %, calibration gas switching) | 0–1 % or greater: < 10 s Under 0–1 %: < 30 s | Over 0–1000 ppm: < 30 s Under 0–1000 ppm: < 60 s |
| Drift | Less than ±2 % F.S. / week | |
| Power supply | AC 85–132 V (option: AC 170–264 V, DC 24 V ±10 %) | |
| Contact input (no-voltage) | Range switch input | |
| Contact output (open collector, DC 25 V, max. 50 mA, NO/NC switchable) | Analyzer abnormality · range echo back (2 or 3 range identification) · ready · concentration upper / lower limit alarm (0.0–9990.0 ppm or 0.0–100.0 %) Any 4 of the above can be assigned; settings can be changed | |
| Range switching | Local / remote / auto range switching (selectable) | |
| First-order lag setting | 0–99 s | |
| Output hold setting | Off, a set value, or the value 5 s before an abnormality During warm-up, HOLD applies if there is a sensor or receiver abnormality | |
| Concentration limit alarms | Upper and lower limits: 0.0–9990.0 ppm or 0.0–100.0 % | |
| RS232C communication | Transmits measurement state, error code, measurement range and value Cable: straight cable | |
Repair & calibration
Serviced by technicians trained by NGK
CJ Tech is a service agent of NGK, the Japanese manufacturer, and repairs and calibrates SH-200 and TF series analyzers.
Other products
Service & custom units
Need to monitor O2 in your process?
Tell us the gas, the range and the tool. We’ll recommend a model or arrange repair and calibration.