Optical Fiber Type Hot Phosphoric Acid Concentration Monitor

Keywords: 3D NAND, SiN(Silicon nitride), Etching, Hot phos(Hot phosphoric acid),

In 3D NAND manufacturing process, dozens of layers of SiO2 and SiN are deposited, and the SiN layer is selectively removed using hot phos.
In this process, the desired etching rate can be achieved by controlling the concentration and temperature of the chemical solution.
Previous products have difficulty to measure high temperature chemicals, but the CS-620F is able to measure at high temperatures  up to 170 C degrees. 
Continuous Measurements are made using absorption spectroscopy, which requires less maintenance and fewer consumables versus other methods. 

Segment: Semiconductor
Manufacturing Company: HORIBA Advanced Techno Co., Ltd.

Key features

High concentration phosphoric acid up to 92% can be measured

No cooling mechanism and cooling time is needed.
Direct measurement is possible without cooling high-temperature phosphoric acid (140 to 170°C) in the circulation line.

PFA is used in the sample wetted area to reduce contamination risk.

Contributes to significant reduction in equipment downtime by adopting semi-annual background correction cycles.

Contributes to faster concentration feedback control by updating measured data every 3 seconds


▶ Measurement results
The sample (actual solution) measured for 1 hour shows exellent stability.

▶ Measurement conditions
Measurement Cycle: every 3 seconds   Measurement time: 1 hour   Moving average: 16 times 
Sample concentration (Initial Sample Concentration)   H3PO4: 92.2%   H2O: 7.8%   Sample temperature: 141°c

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Measurement principleAbsorption spectroscopic method
Calculation principleTemperature compensation type multivariate analysis

Measurable range

 ComponentMeasurable range
Analog output
1st solutionH3PO485.00-92.00+/-0.1085.00-100.00
・ Repeatability is defined by maximum error from average (1 hour).
・ In the case of low temperature measurement (140°C) and high temperature measurement (170°C) with the same chemical,
there is possibility of discrepancy (Maximum +/- 0.30%).
of Measurement
1) Measurement interval: Approx. 3 sec. (minimum)
2) Moving average: 16 times
Connection fitting size1 inch or 3/4 inch
Sample conditionSample temperature: 140 to 170°C
Atmospheric temperature, Chemical temperature fluctuation: within +/- 1°C (period of time : 1 hour)
Input pressure: 0.2 MPa or less
Pressure fluctuation: 0.02 MPa or less
Flow rate: 1 to 30 L/min
Air(for operation and purge)Connection port: 4 mm O.D. quick joint
Pressure: 0.2 MPa ± 0.02 MPa
Power source100 to 230 V AC (Single-Phase), 50/60 Hz
Power consumptionApprox.85 VA (Transient electric current at the time of the start is excluded)
CommunicationParallel I/O, RS-232C, Analog output
Dimension(Monitor) 200 (W) × 308 (D) × 78 (H) mm
(Lamp unit) 200 (W) × 262 (D) × 100 (H) mm
(Sample cell) 240 (W) × 209 (D) × 205 (H) mm
Weight(Monitor) Approx.3.6 kg
(Lamp unit) Approx.2.8 kg
(Sample cell) Approx.3.0 kg
Ambient temperature(Monitor, Lamp unit) 20 to 30°C
(Optical fiber, Sample cell) 20 to 100°C
* Sudden temperature change should be avoided, within +/- 1°C/1hour
Ambient humidity(Monitor, Lamp unit) 40 to 70% (Should be no dew condensation)
Slanting angle of installation(Monitor, Lamp unit) Within +/-1 degree
(Sample cell) Please install so that air bubbles do not stay up.
Optical fiberLength: 5 m, Bend radius: R150 mm


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