BHF Concentration Monitor, CS-137

Overview

The CS-137 is a high-precision chemical solution concentration monitor designed to meet the strict demands of semiconductor wet-etching processes. Etching processes use BHF solution to etch silicon oxide and remove particles from the wafer surface. The CS-137 continually monitors each component of the BHF solution (NH4F/HF/H2O), alerting the user each time the solution is replaced or replenished. This allows you to maintain the concentration of the BHF solution within the required component ranges, while eliminating unnecessary solution replacement.

Features

  • The short 3-second measurement cycle supports concentration control for 300mm processes.
    A short measurement cycle of approximately three seconds makes it possible to track concentrations close to real time. Fine-tuned concentration control makes it suitable for batch-type baths as well as single-bath cleaning devices.
  • The compact design of the CS-137, only two-thirds* of our previous model allow for easy integration into your wafer cleaning system.
    *Compared to the CS-327 series.
  • Fewer lot defects in the cleaning process help improve yield
    An output from the monitor is used for automated spiking control of BHF solutions, enabling a high level of repeatability of your cleaning process. As a result, lot defects decrease in the cleaning process, which helps to boost the overall yield.
  • Fully automated measurement simplifies control
    Measurement is fully automatic, no control is required once the system has been installed and measurement has begun. Air is used for reference spectral measurement. In addition to the chemical components the water concentrations can also be measured, allowing for continuous tracking of changes in water concentration due to evaporation of the solution and adherence to the wafer. This allows fine-tuned control of silicon-oxide etching.
  • Comprehensive counter measures to eliminate air bubbles enable continuous measurement
    A built-in bubble removal function removes air bubbles immediately before the flow cell, which allows continuous measurement of the solution as it is flowing.
  • The monitor uses a low-voltage (24 VDC) supply, with a load in the region of 45W makes it energy efficiency. An internal leakage sensor is also installed to detect solution leaks, so that the supply of BHF solutions can be shut off in the event of an emergency.

Manufactured by HORIBA Advanced Techno

Specifications

Model

CS-137

CS-137-2503

CS-137-1003

Measurement sample

BHF (Hydrofluoric acid/Ammonia fluoride solution)

Measurement principle

Absorption spectrometry

Concentration computation principle

Temperature-compensated multivariate analysis

Measurement range

NH4F: 15.0 to 25.0 %
HF: 0.00 to 3.00 %
H2O: 72.0 to 85.0 %

NH4F: 0.0 to 10.0 %
HF: 0.00 to 3.00 %
H2O: 87.0 to 100.0 %

Reproducibility

NH4F: ±0.3 %

NH4F: ±0.3 %

(Peak to peak)

 

HF: ±0.25 %
H2O: ±1.0 %

HF: ±0.25 %
H2O: ±1.0 %

Chemical

Temperature

20 to 30 °C

conditions

Flow rate

20 to 60 ml/min.

 

Pressure

0.10 to 0.20 MPa

Measurement cycle

Approx. 3 seconds minimum

Equipment temperature

20 to 30 °C

Operation panel

1)Temperature level display:
Ammonia fluoride solution, Hydrofluoric acid, Water

2)Alarm display (Ammonia fluoride solution, Hydrofluoric acid):
Concentration low-low limit, Concentration low limit,
Concentration high limit, Concentration high-high limit

3)Alarm value settings
(Ammonia fluoride solution, Hydrofluoric acid):
Concentration low-low limit, Concentration low limit,
Concentration high limit, Concentration high-high limit

Serial input/output

RS-232C
1)Concentration data:
Ammonia fluoride solution, Hydrofluoric acid, Water

2)Alarm value settings
(Ammonia fluoride solution, Hydrofluoric acid):
Concentration low-low limit, Concentration low limit,
Concentration high limit, Concentration high-high limit

Parallel input

12 to 30 V DC (photocoupler insulated)
Parallel concentration alarm (ON/OFF)

Parallel output

Maximum current when open collector output is ON: 5 mA
Maximum voltage when open collector output is OFF: 30 V
1)Alarm output: Ammonia fluoride solution, Hydrofluoric acid:
Concentration low-low limit, Concentration low limit,
Concentration high limit, Concentration high-high limit
2)Device error (including liquid leakage)
3)Under measurement

Analog output

4 to 20 mA (2 outputs: NH4F concentration, HF concentration)

Power

24 V DC ±10%, 2 A

Dimensions

205 (W) x 329 (D) x 269 (H) mm

8.1 (W) x 13 (D) x 10.6 (H) in

Mass

Approx. 11 kg

Connection pipe size

For inlet and outlet: Outer diameter 6 mm (inner diameter 4 mm)

Pipe connection

Nippon Pillar Super type