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Wet Bench Solvent, wbflexsolv-1 and -2

The Solvent Wet Bench is used for manual solvent cleaning of silicon wafers, tweezers, glassware, or any other inert objects such as equipment parts. The bench is equipped with a carboy to collect solvent waste , two ultrasonic baths, one hot plate for heating solvents in beakers, and a N2 gun for drying.

Picture and Location


The tool is located at C4 on the Lab Map.

Process Capabilities

Cleanliness Standard

 The wbflexsolv1and2 appears in all three equipment groups (clean, semiclean, and gold).

Performance of the Tool

What the Tool CAN do

  • This wet bench is for solvent processing of standard and non-standard materials. Such materials include wafer pieces or substrates with gold or other non-standard films. All processing is done manually in labuser-provided labware (beakers, dishes, etc.). Any labware (Teflon cassettes) provided at this bench is considered gold-contaminated.
  • Substrates may be of most any type, size, shape and any material, subject to the constraints in the Materials Allowed section. GaAs is allowed for processing only in labuser-provided labware.
  • SNF standard solvents (consult the Materials List on the SNF website for acceptable chemicals) are allowed at this bench, for standard processing only. Consult staff if your work requires non-standard processing conditions (such as elevated temperatures, unusually extended process times, or mixing of chemicals), even if standard SNF solvents are to be used.


What the Tool CANNOT do

  • There are no automated wafer processing modules at this station.


How to Become a User


  1. Read all material on the SNF website concerning the wbflexsolv-1 and-2.
  2. Watch the SNF wbflexsolv carbon dioxide fire suppression movie:
  3. Contact SNF training contact on the Equipment Summary page.


Operating Procedures


System Overview

This is a stainless steel wet bench, it contains (from left to right):
A carboy system to collect solvents, two ultrasonic baths (the larger bath fits a 190 mm beaker for one 6 inch wafer and the second (smaller) bath fits a 125 mm beaker for one 4 inch wafer), one explosion proof hot plate in stainless steel well with controllers mounted in the upper panel,  and two N2 guns.

Chemical Hazards

Only SOLVENTS (flammables) are to be used at this wetbench (no Chlorobenzene). You must be familiar with the Material Data Safety Sheets (MSDSs) of the chemicals you will be using and understand safe chemical handling procedures before working at this station. Acids or bases are not allowed.
Solvents commonly used at this bench are:
Isopropanol (IPA), Flash point: 12C (54F)
Acetone, Flash point: -20C (-4F)
Methanol, Flash point: 12C (54F)

In air, above a critical temperature, called the "flash point", the vapors from a flammable can ignite and explode. The source of ignition may be heat (such as a hot plate) or a spark (such as from an electrical tool). Because the vapors can travel over considerable distances, the source of ignition can be far away from the flammables container itself.
Always work well within the exhausted area of bench (behind the red line). The air pulled into the exhaust area will keep the concentration of vapors below the flash point. Where possible, minimize the quantities of flammables used. Before working with flammables, always note the location of the nearest safety shower and fire extinguisher. Flammables should be stored in the designated flammables cabinet; no flammables may be stored at the bench.

We are required by the Stanford University - Utilities Services (Environmental Quality and Water Efficiency) to distribute the Best Management Practices (BMP) fact sheet, you'll find the link here in the Stanford University - Utilities Services folder.
Please read the fact sheet and reduce the amount of pollutant for example by using smaller quantities of chemicals.


Equipment Hazards


Fire Suppression:

This bench is equipped with a carbon dioxide fire suppression system:
wbflexsolv CO2 system

When actuated, 150 pounds of carbon dioxide will rapidly flood the work bench, displacing oxygen to quench the fire.  The fire alarm will also sound to evacuate the building.  This system is actuated:

1.      Automatically, when any of the infrared detectors senses fire.  There are two detectors located above the work surface and one below the work surface in the plenum. 

2.      Manually, by activating the pull station located on the right-hand side, facing the bench.


new wbflexsolv pull down CO2

When actuated, the fire alarm beacon on the front of the bench will sound and flash and the CO2 will discharge immediately.  There is no “abort” option.  

wbflexsolv fire alarm

Shortly thereafter, the building alarms will sound for evacuation.

The release of CO2 may present two hazards to the user: 

1.      The rapid release may drive flames or chemicals on the benchtop toward the user.

2.      CO2 is an asphyxiant.  While the cleanroom is well-ventilated and should disperse the CO2 quickly, the immediate area will be oxygen-deficient. (Breathing of oxygen-depleted air can lead to death by suffocation.)

If the CO2 system is actuated while you are using it, do not attempt to retrieve your samples or otherwise reach into the bench and do not cross in front of the bench; instead move away from the front of the bench and evacuate the building.


Precautions Against Fire Hazards:

Do not leave the bench unattended when you are using the hot plates. Be sure that the Hot Plates are turned off when not in use.
Do not leave the bench unattended when you are using the heated ultrasonic bath!

The only drain on this bench is to the solvent collection carboy system. DO NOT WORK WITH ANYTHING OTHER THAN SOLVENTS AT THIS STATION -- If acids are poured down the drain A VIOLENT ACTION WILL OCCUR.



Input power is 208 volts AC, three phase at 30 AMPS. Only qualified personnel are allowed to work on the electrical parts of this system. If any electrical problems are seen with this system, press the EMERGENCY POWER OFF button, shut the system down and contact Maintenance staff. Pressing the EMERGENCY POWER OFF button will shutdown the hotplates and the ultrasonic bath.


If the exhaust shuts down while there are solvents in the bench press the EMERGENCY POWER OFF button and EVACUATE THE LAB using one of the red pager phones.

Process Hazards

General process hazards involve handling of chemicals and materials which come into contact with chemical used at this station. Wet benches are potentially the most dangerous operations in the lab. Be sure you understand all hazards and proper handling procedures before working at any wet bench.


  1. Make sure the exhaust is working.
  2. Be aware of the location of the nearest safety shower and eyewash.
  3. Wear safety glasses or face shield and solvent resistant gloves.
  4. Check the bench for any damage or any other obvious problems. Notify Maintenance if any problems are observed.
  5. Users are not allowed to make reservations.
  6. User has to be qualified at wbflexsolv.
  7. Enable wbflexsolv-1 for the ultrasonic baths or wbflexsolv-2 for the hot plate.
  8. Make sure the main power is on (Main and System lights are green), light on is optional.
  9. Only SOLVENTS may be used at this wetbench. Any of the SNF-approved solvents may be used at this bench. Any non-SNF-approved solvents must undergo safety and contamination review by the ProM Committee.
  10. Beakers are not provided, only Teflon cassettes are for common use, your wafers will be "gold" contaminated.
    Please don't use labware from other benches!
    You are responsible for supplying your own labware. Label it with your name and equipment group: contaminated,  semiclean, clean, or GaAs contaminated. Semiclean or clean labware has to go through a decontaminating process, contact staff.
  11. Fill out a "IN-USE HAZARDOUS CHEMICALS" card for each open container with liquid.
  12. Transfer solvents from the flammable cabinets to this bench in a metal cart, never hand-carry chemicals.
  13.  Always open bottles under the exhausted area, about 6 inches under the hood, to prevent fumes from escaping into the room. Place the bottle cap upside down on a bench. Do not touch the inside of the bottle cap or the area around the mouth of the bottle with your gloves
  14. The bench has two heated ultrasonic baths used for ultrasonic cleaning of wafers (pieces to 6" wafers only).
    Don't leave the bench while working with heated solvents!
    The baths are filled with DI water (from wet bench flexcorr-3 and-4) up to the liquid level line. The left bath fits a 190 mm beaker for one 6 inch wafer and the right bath fits a 125 mm beaker for one 4 inch wafer. Fill out a "IN-USE HAZARDOUS CHEMICALS" card for the solvent. Be sure to drain the solvent into the carboy when you are through, turn off the ultrasonic bath and turn off the heater to the ultrasonic when you are finished using it.
  15. There is one hot plate with the controller mounted in the upper panel.
    The controller regulates the temperature of the hot plate, not the solvent inside of the beaker!
    Always keep a thermometer inside of the beaker to control the heat. 
    Don't leave the bench while working with heated solvents!
    Switch off the hot plate
    when you are finished!
  16. Collect solvent contaminated solid waste like wipes, gloves or labware in a zip-lock bag, close the bag within the exhausted area and place the bag in a hazardous waste container in the photolithography area.



  1. Solvents should be drained into the solvent drain.
    wbflexsolv solvent drain

    Use wipes to collect metal lift off or other solid materials, like peeling resist.
    Don't clog the solvent drain!
    There are four carboys for liquid solvent waste under the bench, 2.5 gallons each.

    wbflexsolv carboys
    If the first carboy is full, the light for the first carboy on the control panel will be on, report on Badger that the first carboy is full. The solvents will automatically drain into the second carboy.
    If the second carboy is full, the light for the second carboy on the control panel will be on, report on Badger that the second carboy is full. The solvents will automatically drain into the third carboy.
    If the third carboy is full, the light for the third carboy on the control panel will be on, report on Badger that the third carboy is full. The solvents will automatically drain into the fourth carboy.
    If all four carboys are full, all four lights are on, shutdown the bench and contact maintenance.

    wbflexsolv carboy alarm system

    Don't poured acids done the drain, a violent action will occur.

  2. Turn off the hotplate or ultrasonic baths.
  3. Leave the station in a neat condition.
    Do not leave wipes or blue cards on the surface of the bench, they will be sucked into the exhaust system or get onto the hotplate.
  4. Disable wbflexsolv-1 or -2.


Additional Alarms:

wbflexsolv upper control panel

exhaust: shutdown bench, evacuate the lab (make announcement using one of the red pager phones), contact staff


plenum: shutdown bench, contact staff




The facilities of this Solvent Wet Bench are as follows:


Exhaust Scrubbed


House Nitrogen

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