Nanofabrication Facility: Wetbench SOP
Rev. 02, 06/08
Author: Mario Beaudoin, Email: [email protected], Phone: 604-822-1853.
Purpose
To standardize operating procedures for the lithography room wetbenches and spinners in order to ensure operator
safety and process cleanliness. This SOP is not meant to replace the AMPEL Nanofabrication Facility
Members' Laboratory Guide which can be found on the webpage at www.ampel.ubc.ca/nanofab/ . Please read the
Laboratory Guide carefully.
Hours of operation and buddy system
• Regular hours are from 9:00 am to 6:00 pm on normal weekdays
• The buddy system is in force at all times for “dangerous” processes
• A remote buddy system is in force for “relatively safe” processes as described below. (A remote buddy is
someone with FULL access to AMPEL, is in the building and only a phone call away and will check on you
at specific intervals)
Qualification Levels
• Basic: users can use the spinners, DI water, acetone, methanol, ipa, resists, and developer. These, and only
these, processes are also permitted after hours with a "remote buddy".
• Strong acids: users need to verify their process with the cleanroom manager and get independent
qualification on both usage and disposal.
• HF and BOE: this is potentially our most dangerous chemicals and require an independent qualification.
Safety
Every user should know and be able to answer questions on:
• How to handle chemicals
• Where to find the protective gear
• how to dispose of aqueous chemicals
• how to dispose of organic chemicals properly
• where MSDS's are
• how to determine the chemical compatibility of a glove
• what to do in case of a chemical spill (small, large)
• what to do in case of an HF spill
• what to do in case of HF exposure
• how to store chemicals properly
Process Cleanliness
Every user should know and be able to answer
questions on:
• principle of the wetbench operation
• materials incompatible with the
wetbench
• how to pour aqueous chemicals out of
bottles
Figure 1 : The Nanofabrication Facility wetbench.
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The Wetbenches
The cleanroom wetbenches consist of a
laminar flow with a net inward air flow. The air
is blown from the top and exhausted at the
bottom through the vent grids. For this flow to
function optimally, it is important that the vent
grids not be blocked. A common mistake is to
place paper wipes on the front exhaust grids. It
is important to make sure that the wetbench fan
is turned on so that the laminar flow is
operational. There is a big red button on the
Nanofabrication Facility: Wetbench SOP
Rev. 02, 06/08
front center of the “old” wetbench which turns off the power to the outlets also found on the front (see Figure 1).
The “new” wetbench does not have this red button.
The wetbenches contain some common use items: tweezers (metal and fluoroware), timers, thermometers,
development trays (5x7 in photographic trays), squeeze bottles (acetone, propanol, methanol) and waste HF
container. There is also a glassware drying rack and a limited amount of common use glassware (beakers, graduated
cylinders, etc.). In addition, there are digital hotplates, an ultra-sonic (US) bath and spinners. You will also find two
clearly identified waste solvent beakers which are to be used for temporary recuperation of solvents (eg when using
the squeeze bottles). One beaker, labelled “non-halo” is used to recuperate non halogenated solvents. The other
beaker, labelled “halo”, is used for halogenated solvents. Halogenated solvents are those containing halogens (next
to last column of the periodic table F, Cl, Br, I & At). In the cleanroom, we mostly only have chlorinated solvents
such as chlorobenzene and trichloroethylene.
On either end of the “old” wetbench are sinks with a DI water gooseneck, a DI water gun and a nitrogen gas
gun. The goosenecks and guns have taps in the front of the wetbench. In the middle of the wetbench is a small
double-sink originally designed for rinsing; we are not currently using it.
The “new” wetbench has a single sink but 2 DI water guns. It also has a tap water gooseneck on its north
end; this is usually connected to the TMAH silicon etching setup.
Wetbench Chemicals
The Nanofabrication Facility keeps an inventory of commonly used chemicals which are stored under the
wetbenches and in the flammables cabinet. Note that chemicals under the wetbench are separated according to
compatibility in properly labelled secondary containers. These include CMOS or electronic grade acids and solvents,
as well as some photoresist, developer and stripper. If you bring in a new container from the stock area, be sure to
wipe the outside of the container in the gowning area before bringing it in the cleanroom proper. Chemicals
belonging to a research group (hence, not common use) should be clearly identified with the owner’s name.
Etiquette calls for not using these unless you have spoken with a member of that group first. Unless your process
calls for abnormally large quantities of chemicals, you are welcomed to use any clearly identified cleanroom
chemical. If you want to introduce a new chemical in the cleanroom, please discuss with the cleanroom manager
beforehand to ensure compatibility with current process.
Pouring of chemicals from bottles or containers (dry chemicals) is the most common source of
contamination. Avoid touching the lip of chemical bottles to any glassware or other recipient while pouring. To
ensure your own safety, you top hand should hold the bottle handle while your bottom hand is holding the bottle
bottom from the same side as the handle (avoids dripping chemicals from reaching your hands). After pouring acid
from a bottle, put the lid back on, put the bottle in one of the sinks and rinse the outside with the DI water gun. Wipe
the outside of the bottle with a wipe and store the bottle back in its proper area. Photoresist is normally poured from
the larger bottle into smaller brown glass bottles and left to settle. Best practice supposes that clean single use
pipettes are then used to aspire photoresist out of the bottle and dropped directly onto your sample in the spinner; this
avoids stirring up the particulate deposits in the bottom of the photoresist bottle.
All flammable chemicals (eg solvents, photoresist) are stored in the flammables cabinets next to the “old”
wetbench.
Wetbench Shared Glassware
We recommend that users bring their own glassware. A limited number of such items are supplied as
shareware, which can be useful for infrequent users, but experience has shown that one cannot trust the cleanliness of
shared glassware. The glassware is found in a tupperware box kept on top of the drybench; glassware should be
returned in that box after it has dried. These beakers have been cleaned and are labelled for the chemical that can be
used in them. Only use chemicals in beakers specifically identified for that chemical.
Beakers and other glassware are never wiped: this actually contaminates them. Beakers used for solvents
may be rinsed with acetone, propanol and DI water and are then hanged to dry. Beakers used for acids are
thoroughly rinsed with DI water before being hanged to dry.
Safety:
The MSDS sheets:
MSDS sheets can be found through the UBC safety website; specifically at
http://www.hse.ubc.ca/occupational-research/chem_hygiene/ch_safety_info_msds.html. The computer next to the
microscope should have a bookmark to it; if not, start from www.hse.ubc.ca and navigate.
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Nanofabrication Facility: Wetbench SOP
Rev. 02, 06/08
The buddy system
Always remember that, in principle, no one should work alone in the lab for obvious safety reasons. Since
the AMPEL cleanroom is so small however, we are allowing a remote buddy system for “safe” processes (spinners,
DI water, acetone, methanol, ipa, resists, and developer). A remote buddy is one that is immediately available by
phone, is in AMPEL and has key access to all important parts of the building, can come to your assistance within
minutes and will periodically check up on you either by phone or in person.
Protective equipment
Always wear the safety glasses when working in the yellow room if anyone in there is working with
chemicals. Wear the splash goggles when handling chemicals at the wetbench. For more protection, such as when
handling HF, wear the full faceshield. The bunny suits provide some protection but cleanroom will also supply acid
aprons in the near future. Gloves are also an important concern when handling chemicals. The laboratory supplies
latex (rubber), nitrile and the thick “acid” gloves. The specifications and protective ratings of each glove type is
posted on the side of the shelves in the gowning area. Always choose a glove that’s appropriate for the chemical you
are working with.
As you walk through the lab, please pay particular attention to the locations of the safety shower, eyewash
station, first aid kit, fire extinguisher, and emergency exits. These are indicated in the Laboratory Guide.
Water is your friend
Always work safely but be aware that the risk of splashing chemicals on yourself is never nil. Should you
spill a small amount of chemicals on yourself, you should always have an immediate access to flowing water. Turn
on the goose neck DI before manipulating chemicals and leave it running while you are working. The DI water gun
is your next line of defense. Do not hesitate to use it to rinse off chemicals that may have spilled on yourself or the
wetbench. Remember that safety, yours and others’, comes first before any other consideration. There is an
eyewash station and a safety shower in the gowning area. If you splash anything in your eyes however, the DI water
gun is probably faster. If you spill some HF on yourself, rinse the area with large amounts of water, then use the
ointment in the tube on the wetbench (see Figure 1).
Reporting Accidents
The hospital is a short walk from AMPEL. It is better to overreact and have peace of mind. If in any doubt
about your exposure level, please consult a physician. Please also report all accidents to your advisor and the
cleanroom manager.
Chemical Waste Disposal
Empty Chemical Bottles
When you have emptied a chemical bottle, plastic or glass, rinse it thoroughly 3 times. While rinsing bottles
that contained acids or chlorinated solvents, wear a face shield and chemical resistant gloves. Once it has been
rinsed 3 times, the bottle can be taken out of the lab. Clean bottles can be left next to the metal bench in the
gowning area.
Mixing Chemicals Can Be Dangerous!
It is imperative that chemicals be discarded properly (see table at end of document). Mixing chemicals
carelessly can be extremely dangerous. Acids, bases and solvents should never be mixed together in the same
container as this is a potentially explosive reaction. There are labeled red disposal cans in the flammables
cabinets for non-halogenated organic solvents and halogenated (chlorinated) organic solvents. It is important to
dispose of waste chemicals in their proper waste containers. Small quantities of acids (except HF or BOE) or
bases may be dumped it in the sink and washed with large quantities of DI water; make sure that the entire sink,
sides and bottom, is thoroughly rinsed with DI water afterwards (use the water gun). For larger quantities, use a
large beaker of water and dump your acid waste in it. Then, dump this large beaker in the sink and proceed as
for small quantities. AMPEL has acid drains so it is safe to dispose of your acids this way. HF and BOE
(buffered oxide etch; contains 5-10% HF) should never be dumped in the sink: there is a special waste
HF & BOE bottle in one of the wetbenches. As much as possible, we recommend that all solvents be
collected; for solvents used with the squeeze bottles, a large waste solvent beaker is provided in the wetbench.
This large beaker is then emptied into the proper red cans at the end of the session.
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Nanofabrication Facility: Wetbench SOP
Rev. 02, 06/08
Undiluted, non-water-miscible and chlorinated solvents, such as TCA, photoresist or chlorobenzene
should NEVER be dumped in the sink. Disposal of solvents in this manner is not only an environmental threat,
it will also damage the building's plumbing. Chlorobenzene can in fact be saved in a clean and IDENTIFIED
capped bottle for personal reuse. Photoresist that is significantly diluted with acetone can be poured into the
plastic organic waste red cans in the flammables cabinets.
If you need to dispose of a chemical which does not fall under the preceding categories and for which no
waste container already exists, the waste should be placed in a loosely capped plastic bottle with a label clearly
identifying the contents. The bottle should be placed underneath the wetbench (or with the flammables if
flammable) but care should be exercised to ensure that incompatible chemicals are not stored next to each other.
You must clearly identify the waste bottle with your name and the material identification (ie chemical common
name – eg sulfuric acid not H2SO4) and descriptive information such as corrosive/poison/explosive etc. You
must also notify the cleanroom manager and/or lab assistants. If the waste containers are full, notify the
cleanroom manager or a lab assistant.
Wipes
Wipes that have been soaked with acids or bases should be thoroughly rinsed in the sink before being
disposed of in the garbage can inside the lithography room. Wipes that have been soaked with solvents should
be left to dry under the laminar flow hood (wetbench) in the properly identified plastic container. Once the
solvents have evaporated, they may be put in ziplock bags and disposed of in the large blue plastic boxes.
Please do not put solvent soaked wipes into the garbage can.
Transporting Chemicals Safely
When bringing chemicals into the lab, you must use the safety bottle carriers provided in the gowning or
monitoring areas. When you are finished with the carriers, PLEASE return them to this area so that they will be
available for others to use. Also, be sure to check your immediate work area and the yellow room for open
bottles of the desired chemical before bringing a new bottle into the lab.
Telephones
The lab has fully functional telephone sets located in the lithography (yellow), the thin film room and the
westwing. Please refer to the Laboratory Guide for telephone etiquette. In an emergency, 911 works. To dial
help from someone on campus, dial 2- (or 7-) and the last 4 numbers of the telephone number. To dial outside
campus, dial 9 before dialing the entire telephone number.
Chemical Spills
All spills, whether at a sink or work surface, must be cleaned up at once, when you are 100% certain that it
is safe to do so. Leave work areas as you would like to find them. Reminder: water and acid/HF look the
same. The best way to clean the wetbench is to use the DI water gun. If using wipes, for instance to clean a
few drops from the floor, follow the instruction for their disposal.
If an accidental large spill occurs and you are concerned about safety, evacuate the room (press the big red
button to sound the alarm), secure the area and use the telephone in another room to report the spill and consult
for a plan of action. Reminder: large quantities of solvent fumes (acetone, propanol, methanol or even ethanol)
can be fatal with less warning signs than acids. Always know the telephone number where you can reach
someone (buddy system).
Don’t be afraid to over-react to a chemical accident or spill: better to look stupid, and be unharmed, than to
brashly act stupid and live with consequences.
Maintenance
Cleanliness
The cooperation of all students and users is required to keep the wetbenches and spinners clean. It is
expected, as a matter of cleanroom etiquette, that users wipe down the wetbench after each use. If you must
leave samples or labware in the wetbench for some time, make sure to identify it clearly, including where you
may be reached and when you will be returning. Try to return as soon as possible (normally within an hour or
two).
Equipment Reservations
All equipment reservation is done online at http://www.ampel.ubc.ca/nanofab/ .
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Nanofabrication Facility: Wetbench SOP
Rev. 02, 06/08
Work Storage
Ask the cleanroom manager for shelf space in the rooms you use most often. Alternatively, you may store
labeled closed boxes in the shelves on the “dirty” side in the gowning room (remember to wipe them down with
iso-propanol when taking them back in the clean areas). Always store your parts after you have completed your
work for the day.
Space: The cleanroom has limited space for lab member storage. Members are asked to expediently clean out
shelves and then remove their nametags and marker tape when they are no longer needed. Send e-mail to
[email protected] so these spaces can be reassigned. Space that has not been used in a long time will be
reassigned to more regular users.
Chemical Disposal Summary
Chemical
Disposal Method
HF, BOE (contains HF)
Pour in the HF waste bottle; Put bottle in sink, pour into bottle using a
funnel, cap the bottle and rinse the funnel, the bottle, the sink and your
beakers with copious amounts of water. Wipe outside of bottle and put
back in its place. The waste HF bottle is currently stored in the new
wetbench.
Other acids or acid solutions
compatible with water.
For less than 100 ml; pour in the sink under running water. Rinse your
beakers and the sink thoroughly with water. For more than 100 ml,
take a large beaker half full with water and slowly pour your acid
solution into it. Dispose of water+acid solution as you do with 100 ml
quantities. Repeat as necessary.
Bases (eg most developpers)
Follow the same procedure as with acids.
HMDS (photoresist primer)
There is a waste container in the flammables cabinet. HMDS should
never be mixed with water or alcohol.
Non-Halogenated organic solvents (eg
IPA, Acetone, Methanol)
Use the specifically marked beaker (Non-Halo) on the wetbench for
temporary disposal. Remember to empty the beaker in the nonhalogenated waste (read tag) red can found in the flammables cabinet.
Halogenated organic solvents (eg
chlorobenzene, trichloroethylene)
Use the specifically marked beaker (Halo) on the wetbench for
temporary disposal. Remember to empty the beaker in the halogenated
waste (read tag) red can found in the flammables cabinet. Some users
actually reuse chlorobenzene which is fine.
Photoresist
Dilute with acetone and dispose of as with other non-halogenated
solvents.
Other liquids or substances?
Bring the MSDS sheets with you and discuss with the cleanroom
manager to determine a safe way of storing and disposing. NB: no
inherently unsafe substance will be allowed in the cleanroom.
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