GENERAL WET BENCH SAFETY AND USES SOP October 2013 GENERAL SAFETY RULES You must be a certified client to enter the Cleanroom and work at the wet benches. You must have received the "WET BENCH TRAINING" provided by a Cleanroom staff member. You may request this training using the online form available http://louisville.edu/micronano/users/training-dicing-photomask-requests You must wear the personal protective equipment (PPE) at all times when using the wet benches. For more PPE information refer to the Safety Manual. You must never work alone. Always have a buddy in the Cleanroom, who is also a certified Cleanroom client, when working at a bench. SPECIFIC WET BENCH RULES DO NOT work with acids/bases in the solvent hoods. DO NOT work with solvents in the acid/base hoods. DO NOT cross outside the yellow line of the wet bay carrying any new or opened chemical bottles or wear PPE outside this bay unless working under emergency situations or following spill cleanup procedures. DO NOT dump chemicals from bench tanks. Tanks should be drained by Cleanroom staff members only. DO NOT fill up a tank unless it is a solvent tank. Acid and Base tanks must only be filled by staff.
The hot NANOSTRIP tank should be turned off when the fabrication process is complete. Just press the POWER OFF button located on the setup panel. You are NOT ALLOWED to bring new types of chemicals inside the cleanroom without approval. Fill out a chemical request form if you are interested in having a new chemical available in the cleanroom. WET BENCHES BY PURPOSE Each bench is designed for a specific type of process. An acid bench is dedicated to handle acids and a solvent bench is dedicated to handle solvents, the same protocol is followed for bases and oxidizers. **The RCA Bench will never have solvents. The EDP, KOH, TMAH Benches may have IPA as part of some mixture. Please refer to the tables below to learn about the purpose of each wet bench and always make sure you are using the correct chemical on its corresponding work station. Processing utensils allowed at the Benches: The following is a list of processing utensils allowed at the chemical wet benches: Tweezers Teflon wafer boats. (Glass wafer boats must not be used at any bench) Wafer boat holders (made of Teflon only!) Cleanroom wipes Glass and Pyrex Beakers (For solvents, NANOSTRIP, Nitric Acid and Chrome, Silver and Gold Etchants) Polypropylene beakers (for BOE, Hydrofluoric Acid, MF-319 and WNRD) Photoresist bottles (including amber dropper bottles), allowed at the Spinners bench only! Wafer containers; keep them away from chemical tanks! Chemical and waste bottles (only when in use). Please remember to put bottles back in its corresponding chemical cabinet.
Table 1. Location: Wet Etch Bay Bench Name Chemicals that can be used Processes allowed at this bench 305 Acid Hood LF8-2 RCA Clean Hood 301 Solvent Mems 308 EDP Etch 307 Base Hood Electroplating Hood NANOSTRIP Acetic Acid Aluminum Etch Chrome Etch NHA Nitric Acid Phosphoric Acid Sulfuric Acid Hydrochloric Acid HF 40:1 HF 49% BOE Ammonium Hydroxide 2 Propanol Acetone Baker BTS-220 Methanol Ethanol Gold Etchant Copper Etchant EDP KOH TMAH IPA (2-Propanol) Ammonium Hydroxide DI Water Nickel Sulfamate NANOSTRIP Bath Aluminum Etching Chrome Etching BOE 6:1 Bath RCA-1 *NO METALS RCA-2 *NO METALS HF Bath *NO METALS BOE Bath *NO METALS *GENERAL RULE: Only process samples that have never seen a metal. 2-Propanol Clean Acetone Static Bath Methanol Clean LIFT-OFF Hot DI Water Ultrasonic Bath Gold Etching Copper Etching EDP Etching KOH Bath TMAH Bath Electroplating
Table 2. Location: Lithography Area Bench Name Chemicals that can be used Processes allowed at this bench LF8-1A Solvent Develop Hood 115 X Base Develop Hood 153 X Hotplate Spinner Combo Table 3. Location: Thermal Bay 2-Propanol Acetone Methanol Toluene WNRD Xylene Baker BTS-220 Chlorobenzene Pyralin PD Rins MF-319 TMAH Positive Resist Negative Resist Adhesion Promoter SU-8 Polyimide Photoresist Removal Toluene Bath WNRD Pattern Developing Xylene Bath Chlorobenzene Bath Pyralin PD Rinse MF-319 Pattern Developing TMAH Bath Spinning/Coating *GENERAL RULE: SU-8 must only be used at left most spinner and left most hotplate Bench Name Chemicals that can be used Processes allowed at this bench Spin On dopants 725 Hot Plate Spinner Adhesion Promoters Combo Hood Spin on Glass Spin On/Coating Polyimide WHEN TO USE A TANK AND WHEN TO USE A BEAKER You Must Use a Beaker If: Your process will react with or contaminate a tank, OR Your sample is smaller than a 4" wafer and there are no sample holders available for your wafer size. (In this case, neither use a tank nor a QDR afterwards), OR If your metal lift off process requires the use of a Lab Q-tip, OR If your process will make the chemical unusable afterwards, OR If the chemical you are going to use does not have a tank assigned. Additional Rules: Use Polypropylene beakers for HF and BOE solutions. Use only glass beakers for heated chemical processes. Use glass beakers processes on small samples involving chemicals such as NANOSTRIP,
nitric acid, sulfuric acid, MF319 (this is polypropylene or glass), WNRD (this is polypropylene or glass) chrome, nichrome, copper, gold and silver etchants. Use glass beakers for solvents. DO NOT use household Pyrex pans or Bowls for ANY hotplate or heated process. DO NOT use polypropylene beakers for ANY hotplate or heated process. You Should Use a Tank If: You have one or more 4" wafers to process. The chemical you are going to use is available at a tank and it doesn't follow the characteristics for beaker processing (explained above). If you need to process in a static or heated bath. CHEMICAL DISPOSAL You Must Use a Cup Sink If: You need to dispose of Non-Halogenated solvents at a solvent bench. Example: SU-8 Developer, IPA, Methanol, Acetone, WNRD, etc... You need to spray wash your samples with Non-Halogenated solvents from a hand held spray bottle. You need to dispose of EDP at the EDP Etch bench. You Must Use an Aspirator If: You have left over chemical waste in a beaker which can be disposed of down the sink. Refer to the chemical disposal rules for aspirating chemicals on the "DISPOSAL RULES" section below. You Should Never Dispose of Chemicals from a Bench Tank Without Asking for Cleanroom Staff Assistance You Should Dispose of Used Chemicals from a Beaker Down the Sink If: You have Al Etch waste in a beaker at the 305 Acid Hood. You have HNA waste in a beaker at the 305 Acid Hood. You Must Use a Bottle to Store Hazardous Waste If: You need to dispose of chrome, nichrome, silver, copper or gold etchant that is not reusable. Please use a glass waste bottle to store gold, copper, and silver etchant waste. You need to dispose of a Chemical that cannot be drained or dumped down the sink and that cannot be aspirated. Consult the Chemical Disposal Guide (next section). GENERAL RULE: Once bottles are filled up to full container capacity you must leave this bottle in its corresponding chemical cabinet located in the Wet Etch or Photolithography
Bay. Please contact Cleanroom staff for additional information. You Must Use a bottle to store reusable chemicals such as lightly used Chromium, Gold, Silver or Copper Etchant: To store reusable chemical solution such as chromium, nichrome or gold etchants. GENERAL RULE FOR REUSABLE SOLUTIONS: Using the *Hazardous Chemical Waste labels provided, make a note on the bottle indicating the chemical name (or solution contents by percentages), the date and write down "REUSABLE SOLUTION" on both sides of the bottle. There may be already a used bottle of this chemical available inside the chemical cabinet. Please look for a bottle in use before creating a new one. CHEMICAL DISPOSAL GUIDE What to do with an Empty Bottle: Empty plastic or glass bottles must we kept back in the lower shelf of the chemical cabinet where it belongs, so that a staff member can find and recycle them. For information on this procedure please refer to the Used Bottle Procedure SOP. Please place empty bottles in bottom of respective chemical cabinet. Cleanroom staff will clean and label them. For an empty photoresist bottle, please DO NOT leave it inside the photoresist fridge. Store it in the lower shelf of the flammables chemical cabinet located in the lithography bay. Chemical waste which needs to be stored in a waste bottle: Halogenated Waste (all solvents will an element Group 17(old-style: VII); F, Cl, Br. Chlorobenzene waste (an example of halogenated solvent waste) KI gold etchant waste Copper etchant waste Chromium etchant waste Nichromium etchant waste Silver etchant waste Gold etchant waste All electroplating supplies (Be sure to check the corresponding chemical for already in use hazardous waste bottles. You may also find cleaned bottles for chemical waste use below the Cleanroom wipes table at the Wet Etch Bay, please make sure you label its contents and date it on the provided sticker-label. If an empty bottle cannot be found please ask for assistance.)
Chemicals that can be dumped down the sink and/or aspirated: MF-319 TMAH KOH TMAH/IPA solution Hydrochloric Acid (no metals) BOE (no metals) JTB-111 (no metals) RCA-1,2 Solutions (no metals) Ammonium Hydroxide NANOSTRIP Acetic Acid Aluminum Etch NHA Nitric Acid Phosphoric Acid Sulfuric Acid (115 X Base Develop Hood) (115 X Base Develop Hood) (307 Base Hood) (307 Base Hood) Chemicals that can be dumped in a cup sink: Acetone Methanol IPA Ethanol Butyl Acetate Toluene Xylenes BTS-220
WNRD Pyralin PD Rinse NANO Remover PG Non Halogenated Sovents Methanol IPA Ethanol NMP 1165 Photoresist Remover WET BENCH INSPECTION PROCEDURE Wet Benches should stay on overnight (closing N2 valves could present a fire hazard). All beakers (except those left for overnight processing) must be emptied, cleaned and wiped dry If you are leaving a beaker full for overnight processing, you must label it, date it and sign it. There is an informative sign in sheet on the wall by the Cleanroo wipes table where information about your overnight process must be provided so that you can be contacted if an issue occurred. Wet Bench Inspection: "All Finished?" Before you walk out of a bench you should make sure the working station is left in proper condition. Static/Ultrasonic Baths, Etching and Lift Off processes may take several hours and often users leave their wafers processing overnight. If you see wafers inside a tank, bath or on a hot plate you MUST NOT TURN OFF THIS UNIT. If you are leaving beakers or pans with a chemical content and your sample in it, leave a note over the bench shield near the beaker with the name of the chemical, the date and your name, as well as on the informative sign in sheet. Other details to inspect before leaving a wet bench are: Dispose of all wipers used. Clean wipers must be left on a table outside the wet bench. Beakers must be left empty, clean and dry. (If your process is completed) Sinks and cup sinks, should be emptied and drained. Leave sinks free of beakers, tweezers etc. Nitrogen guns must be placed back inside their compartments. Chemical Resistant Gloves need to be washed and dried with a towel, then placed on a table outside the wet benches. Inspect PPE before returning it to the apron/shield hangers. Please report damage PPE so it can be replaced.