Birck Nanotechnology Center BNC 202: Solvent Cleaning Course - PowerPoint PPT Presentation

Birck Nanotechnology Center BNC 202: Solvent Cleaning

Course Overview • Why clean? What is clean? – Chemical / particle contamination – Sample handling • Quick Review – Acid vs Solvent Hood – Required PPE – Birck Supply Room – Getting supplies into the CR • Technique – Good solvent practices – Common mistakes – Personal Integrity

Why care about cleanliness? Chemical contamination can ruin: • Device performance and reliability Equipment controllability and behavior • Particulate contamination can ruin: • Device yield • Process repeatability Contamination of either kind affects your research as well as everyone else’s.

Prevention: Wafer Handling Poor handling practices of samples are the primary cause of defects Tweezers • Use the appropriate type of tweezers at the proper time • (material / size / type) Tweezers are too small and inappropriate for such a large wafer

A Note on Choosing Tweezers The Birck supply room offers 7 316L Stainless Steel types of tweezers for handling your Wide Paddle sample 316L Stainless Steel Narrow Paddle • Choose the right type of tip that makes sense for your size of sample. 316L Stainless Steel Angled Point • Choose the right material for how you plan to use your tweezers. 316L Stainless Steel Straight Point • You may have to buy multiple types:  1 for solvents 316L Stainless Steel  1 for acids Carbon Fiber Tip  1 for clean sample handling 316L Stainless Steel Teflon Coated Wide Paddle Economy Plastic

Prevention: Wafer Handling Transferring samples • Poor handling practices of samples are the primary cause of defects Practice good handling technique such as loading samples from back to front • Poor Practice: Do not reach over wafers to load more wafers. Also notice the exposed skin at the wrist.

Prevention: Wafer Handling Storing samples • Use an appropriate sample storage container – Cassettes for full wafers – Sample boxes for partial wafers and small samples Poor Practice: Good Practice: Samples are stored uncovered Samples are stored protected and and unprotected. segregated from one another.

Review: Solvent vs Acid Hood Acid Hood Label Poly- propylene Table-Top Acid Bottle Storage

Review: Solvent vs Acid Hood Solvent Hood Label Stainless Steel Table-Top Solvent Bottle Storage 9

Personal Protective Equipment Acid Hoods (within the cleanroom) Cleanroom Gloves + Acid Gloves + Cleanroom Suit + Chemical Apron + Goggles + Face Shield ( Only needed if pouring from supply bottles or using HF/BOE ) Solvent Hoods (within the cleanroom) Cleanroom Gloves + Solvent Gloves + Cleanroom Suit + Goggles

Review: Birck Supply Room Please only buy cleanroom supplies through the Birck supply room (and not other stores across campus) When you purchase your cleanroom supplies through Birck, you ensure: • The supplies are cleanroom compatible ( but not yet clean – more on that later ) • The supplies meet cleanroom standards and are compatible within our clean policy. • Many of the supplies will be double bagged to reduce particle contamination. foxl@purdue.edu Add the minion slide here, too

Getting Supplies into the CR 1. Move all supplies into the gowning room. A. If you have many supplies to move at once, do not transport them in a cardboard box. Lorraine can lend you a plastic tote, which you can use and return to her afterwards. B. Take only cleanroom compatible supplies and materials. 2. Place your supplies at the wipe down station 3. Gown up as normal before wiping down your items.

Getting Supplies into the CR 4. Wet a lint-free cloth (with gloved hands) at the wipe down station A. Use 10% IPA / 90% water solution that is provided for you. B. Wipe down all the surfaces of your all your supplies. (Samples excluded) C. Be sure to turn the cloth often so you are not reapplying particles you just removed. D. Once finished, continue into the CR with your wiped-down supplies

Tool Cleaning Before you clean your sample, you have to start with clean hardware. • Everything you buy from Birck’s supply room is cleanroom compatible, but it is not ready for use in the CR. Question: What do all these tools have in common? Answer: They are all dirty when new.

Cleaning Plastics Compatible Not Compatible with Toluene / Acetone / IPA with Toluene / Acetone / *** cleaning • ABS • HDPE • Polypropylene • Polycarbonate • PTFE Teflon • Nylon • PEEK ***But note these plastics are generally compatible with IPA Clean compatible plastics with the 3 solvents in sequence

Good Solvent Cleaning Techniques • Know the best known methods of solvent cleaning – Be deliberate with all movements. Do not rush the process. – Organize your work area before you begin – Prepare the sonicator bath prior to cleaning – Prepare the solvent waste jug with a funnel prior to cleaning – Lay down foil and lint-free wipes for your clean work area – Do not block the air plenum of the hood for your safety – Place solvent bottle caps upside down – Do not touch the solvent bottle to your glassware – Blow dry items only within the fume hood – Handle tweezers only by their handle – There is no need to use an excessive amount of lint-free wipes. – Never place your phone in a fume hood – Clean up after yourself

Good Solvent Cleaning Techniques • Understand how to prevent cross-contamination – Do not touch the lip of your glassware with your hand – Dry the exterior of your glassware after sonication and prior to dumping out used solvent – Do not touch glassware to the waste jug funnel – Do not touch tweezers by their working end – Clean tweezer tubes often through your process flow – Do not store dirty items in clean items (like glassware nested in glassware) – Do not touch the blowgun nozzle to any clean items – Do not use the drying rack for glassware but rather fully dry with the nitrogen blow gun

Common Mistakes • Touching your tweezers by the working end (even with a gloved hand) Placing clean samples on dirty things • • Placing dirty samples in clean equipment • Assuming substrates are clean and ready to use from the vendor • Assuming a solvent wipe-down in the gowning room will clean your glassware • Assuming if it is cleanroom compatible, then it is ready to use Assuming cleaning is not important • • Not thinking through cross contamination • Touching the N2 blowgun to glassware or samples • Drying glassware on the drying rack

Exhibit Personal Integrity • Ask questions – Everyone wants you to succeed. – Do not think you will be looked down upon by asking a question. Raising questions will keep you safe, and keep your research moving forward. – • Do not allow bad habits to propagate – If your colleague is not doing things right, do not be shy about correcting the behavior. • We all make mistakes – Be professional and take responsibility for your action. – Help all users by informing the staff so they can minimize the effect. • This is a shared facility – Everything you do affects you as well as your labmates. – Respect others by doing the chores and work expected of you. – You will gain respect by respecting others.

Leave a Clean Work Area You are responsible for: • Cleaning up small spills • Putting away supplies • Replacing lids on solvent disposal bottles • Ensuring lint-free wipes are removed and properly disposed • Organizing the hood for the next user How would you like to begin work in a mess like this?

Thank You! When you properly clean your samples and labware, you are doing your part in minimizing cleanroom contamination.