LQFE Series, Quartz Filtered Etch Baths

High Temperature Filter Etch Bath and Quartz Weir

FEATURES

• Where quartz is preferred without replacement cost penalty.
• Built for 180ºC aggressive chemistry.
• Simple self-contained system.

BENEFITS

• No imbedded heaters. Save replacement cost over typical quartz.
• Process benefits of self contained fluoropolymer with final wetted quartz.
• Only commercially proven system to match aggressive chemistry to 180°C.
• Smooth surge-less flow from integral filter & centrifugal pump.
• Wetted components of TFE & PFA fluoropolymer .

ENGINEERING SPECIFICATIONS

• Chemical Containment: All plumbing connections, filters and pumps are self contained in the bath. Provides for additional fail safe containment.
• Recirculated Chemical: Process chemistry is pumped through a filter directly into the quartz weir. The entire recirculation loop is only a few inches (mm) long.
• 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 range from 75 to 105 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).
• DI Water Make Up Control: The Lufran^® system uses a LTFEC-J MTC process controller to adjust concentrations of DI water. Our 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 through a tube located next to the filter housing.
• Temperature Control: A self-tuning PID based microprocessor maintains +/- 1°C. System operations and safety circuits are continuously monitored and displayed on the LTFEC-J process controller.
• Process Availability: Reported at 95% to 97% availability per month.
• Filter: 1-micron filter, has proven to be the most effective for Nitride applications. Current users report filter life span approximately 3500-4500 wafers.
• Filter Housing: Made from PTFE. Integral with pump body. Holds 10" Single Open End (SOE) cartridge using standard fluoropolymer 222 O-rings, 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, heater back pressure.
• Initial Heat Up: Depending on system size and normal conditions (i.e., proper PID values open lid, etc.), temperature rise is typically 1.5-2.0°C per minute.
• Tank Assembly:
  Cut out:
    w/ Bezel: 15" x 29" (38 x 74 cm)
    w/o Bezel: 12 3/4" x25 1/4" (33x64 cm)
  Depth:
    w/ Bezel: 15 1/2" (39 cm)
    w/o Bezel: 12 1/4" (31 cm)
• Weir: Semiconductor grade high purity fused quartz. No imbedded heaters in vessel.
• Weir Inside Dimensions:
• For 1 or 2 Carriers
  4" (100mm) carriers:
    11.5" x 7.5" x 7.8"   (29 x 19 x 20 cm)
  5" (120mm) carriers:
    13.5" x7.5" x 8.8"   (34x 19x 25 cm)
  6" (150mm) carriers:
    16" x 8" x 9.8"   (41 x 20 x 25 cm)
• Call for 8" (200mm), 12" (300mm) or custom sizes to fit your processes.

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 fluoropolymer and PVC, and polypropylene.
• 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.

• Case: 316 stainless with cooling channel enclosed in fluoropolymer, PVC, and Polypropylene.
• Connection: Cooling lines 1/8" stainless compression and 1/4" fluoropolymer for N₂.
• Amp Draw:
    9 amp in rush
    7 amp maximum
    4.5 amp normal operating

PUMP SPECIFICATIONS

• Type: Centrifugal. Can be run dry or against blocked filter without damage.
• Impeller and Shaft Sleeve: Solid fluoropolymer.
• 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 180°C.

For more information on this, or any other product, please contact our offices and visit our contact page.