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High Temperature Filter Etch Baths
High Temperature Filter Etch Baths
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Weslan Systems Filter Etch Baths are available in a wide variety configurations. They are engineered to reliably and efficiently filter various chemistries.  Operating temperatures range from sub-ambient to 185 degrees Celsius.

Options include:

  • Material of construction  - Wetted materials include Teflon, PVDF, polypropylene, quartz etc.
  • Capcity - 4" to 12" Wafer Cassettes - FPD
  • Pump Selection (Double Diaphragm, Pneumatic, Electric Sealess brushless).
  • Surge Suppressors (if applicable).
  • Process applications include SC1, SC2, Wafer Clean, Strip, Nitride Etch, Metal Etch, and KOH etch etc.
  • Filter Selection Porosity (, material of construction (Teflon, PVDF, polypropylene, polyethylene).
  • Interior dimensions, wafer cassette capacity (size and number of cassettes).
  • Drain valve or drain adapter.
  • Covers (Hinged  - lift off), Refluxors.
  • Voltage, phase.
  • PID Control packages with / without integral Timers.
  • Remote Pumping / Filtration.

Process Technology (Lufran) LTFE Teflon Filter Etch Bath )to 180 degrees Celsius.

High temperature filter etch bath with manual lid or pneumatic slide opening.


  • Built for up to 180C aggressive chemistry.
  • Simple self-contained system.
  • Capture complete advantage of Teflon.


  • Only commercially proven system to match aggressive chemistry up to 180C.
  • Smooth surge-less flow from integral filter & centrifugal pump.
  • Wetted components of TFE & PFA Teflon.

Engineering Specifications

  • Chemical Containment: All plumbing connections, filters and pumps are self contained in the bath. Provides for additional fail safe containment.
  • Clean Up: Easy clean between process change outs. Flush the system with DI water or peroxide. Some sites use H2SO4. No scheduled system flush is prescribed.
  • Etch Rate: Average etch rates in excess of 75 and 85 angstroms per minute have been reported (temperature and chemical concentration dependent).
  • Maximum Strip Rate Non-uniformity: Reported less than .03 angstroms.
  • Minimum Selectivity: Greater than 18 to 24:1 (nitride to oxide).
  • Process Availability: Reported at 95% to 97% availability per month.
  • DI Water Make Up Control: The system uses a LTFEC-J MTC process controller to adjust concentrations of DI water. The system adjusts for boiling and evaporation of the water in the hot phase up to 180 C.
  • Flow rates are fine tuned per installation and to meet your process requirements. Experience shows an average range of 0 - 200 ml/min.
  • DI water is introduced to the system by a tube located under the inner weir and is mixed immediately by pump agitation.
  • Temperature Control: A self tuning PID based microprocessor maintains +/- 1C. System operations and safety circuits are continuously monitored and displayed on the LTFEC-J process controller.
  • Filter Life: Current users report filter life span of approximately 3500 - 4500 wafers.
  • Filter Size: 1 micron filter, has proven to be the most effective size for Nitride applications.
  • Filter Housing: Made from PTFE. Integral with pump body. Holds 10" Single Open End (SOE) cartridge or stacked filter elements. Integral air bleed standard.
  • Safety Interlock: Cooling water loss, N2 purge loss, internal motor bi-metal thermal fuse, internal heater thermocouple, bubble style liquid level sensor.
  • Initial Heat Up: Depending on system size and normal conditions (i.e., proper PID values open lid, etc.), temperature rise is 1.5-2.0C per minute.
  • 30 to 45 minutes to reach 50 particles at .5m size in H2SO4 @ 120C.
  • Tank Assembly:
    Cut out:
      w/ Bezel: 15" x 29" (38 x 74 cm)
      w/o Bezel: 12-3/4" x 25-1/4" (33x64 cm)
      w/ Bezel: 15-1/2" (39 cm)
      w/o Bezel: 12 1/4" (31 cm)
  • Weir inside dimensions:
    For 1 or 2 carriers
    4" (100mm) carriers:
      11" x 7" x 5-1/2"   (29 x 18 x 14 cm)
    5" (120mm) carriers:
      13" x 7" x 6-1/2"   (33x 18x 17 cm)
    6" (150mm) carriers:
      15" x 7" x 7-1 /2"   (38 x 18 x 19 cm)
    8" (200mm) carriers:
      15-1/2" x 11" x 10-1/4"   (39 x 28 x 26 cm)


Motor Specifications

  • Totally Enclosed: Water cooled, permanent shaded pole, grounded motor, purged labyrinth seal. Exclusive Lufran design.
  • External portion of the motor is protected by a shroud of Teflon and PVC.
  • Top portion of the motor, cap, motor cooling fittings and the motor power cord are all O- ring sealed for vapor protection.
  • Continuous service: Compact and totally encapsulated motor is isolated from aggressive atmosphere. While the motor housing design meets construction parameters as described for NEC Class 1, Division 1, purged electric motor, it is not formally listed. Proprietary N2 bearing purge extends life. Water cooling, and purge patented (4,158,764 4,390,776 - 4,553,024)
  • Maintenance: Usual motor PM cycle is from 6 to 8 months. Two motors are supplied with new LTFE units for rotation through preventative maintenance.
  • Constant cooling water supply and Nitrogen purge flow will enhance and maintain useful life. Do not directly immerse motor in media.
  1/2 HP
  120 vac 60 hz
  110 vac 50 hz
  3400 RPM @ 60 hz
  2800 RPM @ 50 hz
  Shaded Pole
  • Case: 316 stainless steel with cooling channel enclosed in Teflon and PVC.
  • Connection: Cooling lines 1/8" stainless compression and 1/4" Teflon for N2
  • Amp Draw:
      9 amp in rush
      7 amp maximum

Pump Specifications

  • Type: Centrifugal.
  • Impeller & Shaft Sleeve: Solid Teflon.
  • Max Delivery Pressure: Up to 15 psi (103 kPa).
  • Max Flow: Up to 18 GPM (68 LPM) with DI water and without filter.
  • Temperatures: Up to 180C.

Please contact us @ sales@weslan.com or call 530-668-3304 (8:00 AM to 5:00 PM PST)  to specify your Filter Etch Baths.


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