Microfabrication Laboratory
Electronics
Research Laboratory
Department of
Electrical Engineering and Computer Science
Microlab Members' Laboratory Guide
Introduction
This Microlab handout contains
guidelines to assist members working in the Microlab. The objectives of this
guide are to:
►
Orient new members to the Microlab in terms of the facilities
available and their locations in the lab.
►
Familiarize members with the computer facilities which run the
lab; and
►
Review the safety and clean-room policies that must be observed at
all times when working in this class-100 facility. Certain points of etiquette
will also be mentioned.
It is imperative that you maintain
an awareness of safety and clean-room policies whenever you are in the lab.
This will help keep the Microlab a class 100 clean room, and more importantly,
a safe place in which staff and students can work.
Since this guide is meant to
accompany the lab tour, the first section is organized according to the order
in which we will visit the various rooms. Procedural and safety matters will be
discussed as they pertain to each area, and a brief mention of safety equipment
and machinery will be made. The next section will discuss computer usage, and
finally, an overview of clean room procedures for contamination control will be
presented.
I.
Reception Area
Getting into the Lab
Requests for card keys are processed through the Microlab office.
If you already possess a card key, access to the Microlab can be added.
Login Policy
There are two terminals located in the reception area to allow you
to log in. Login is required each time you enter the lab. The computer keeps
accounting records and will monitor and charge you for your time in the lab.
Also, your login allows others to see that you are in the lab so that you can
be notified for any reason (emergency, visitor, etc.). Do not forget to log out
when you leave the lab. Failure to do so will cause the computer to continue
charging you lab time.
Occasionally, the lab's computer goes down (i.e., becomes inoperative).
In this case you will be asked to login manually by entering your name,
date, and times of entry and exit on a form, on the counter next to the
terminals. If manual login is necessary, please be sure to logout when you
leave.
Always remember that no one is allowed to work alone in the lab
for obvious safety reasons. The terminal in the reception area should be used
to check that there is someone else working in the lab before you log in.
Typing labwho or lw at the prompt for login name (after login
into the CAPE) will display a list of students currently logged into the lab.
If the computer is down when you come in to work, check the manual login sheet
to see whether others are working.
If you are found working alone,
you will be suspended from using the lab.
Phone
Policy
Telephones are
available in the Microlab for lab members. Only one telephone line (642-2796)
can be used to dial out of the Microlab and is restricted to local calls only.
Since many lab members may want to use the phone each one should keep phone
conversations short. If you must have a long conversation place or receive the
call on a cell phone. Microlab staff does not take messages for lab members.
Visitors
If you wish to
bring visitors into the lab, you must get permission by e-mailing visitor@silicon,
or speaking directly with Microlab management. Be sure to log your visitors in
under the Visitor category on the wand as soon as you enter the lab (see
Computer Usage section below for details). Do not bring visitors in on weekends!
Study/Graphics
Terminal Area
There is a
student study area on the left as you enter the lab available to all
labmembers. In it, are workstations, PC’s, a Tycom terminal, a telephone, and
miscellaneous reference materials. All lab members are welcome to use this
area. Food and beverages are prohibited.
II.
Gowning Area
Storing
Gowns
Behind the
reception area is the gowning area, which is where lab member and visitor lab
wear is stored. This is where you will gown up. When you are ready to
begin work in the lab, obtain a box (from the Microlab Office) in which to
store your bunny suit, booties and cap. To avoid soiling your other garments,
put the soles of your booties together and store them in a plastic bag
available from the office. Visitor’s garments are hanging on the rack along the
left wall of the gowning area.
Please note that,
though they are disposable, all garments should be used until they are torn or
soiled. Shoe covers should not be discarded until the soles are torn. They
should be checked each time you put them on. These garments are expensive and
should not be thrown away until they are no longer usable. Under ordinary
conditions they can last up to a week with daily use.
Gowning
Up - The Method
When you are
ready to gown up, start from the top, with the cap, to avoid shedding particles
on your labwear as you dress. All your hair must be under the cap. Make sure no
stray strands are sticking out before entering the lab. Hair and dandruff are
common contaminants, which can be easily avoided by paying attention to your
attire. Put on your suit, being sure it is zipped all the way up. Get your
booties (shoe covers) and sit down on the bench. This bench separates the clean
and dirty areas of this front room. The gowning area is dirty,
while the area beyond the bench is clean. Subsequently, you should put
on a shoe cover and swing your leg over the bench so that the sole of the shoe
cover makes contact only with the clean floor. (Conversely, when removing your
shoe covers, you should do so before stepping into the dirty area.) Do
the same for the other foot before proceeding to put on gloves, which are found
in size-labeled boxes by the door leading into the clean room. No one may enter
the lab without gloves or safety glasses!
Three types of
gloves are commonly used in the lab. Each has a particular application and they
are referred to as follows:
a) Surgical Gloves (latex, tan
colored): Located by the door to the lab. These serve primarily to protect lab
surfaces from contamination from dirt and oils on your hands. Must be worn at
all times in the lab.
b) Triple Polymer,
Chemical Resistant (tan colored): These are available from the Office. These must be
worn whenever you work with caustics or corrosives. Be sure to leak check them
before use by inflating them, submersing them in water and checking for
bubbles.
c) Plastic
Polyethylene Gloves (clear): These prevent you from contaminating your wafers, or
anything that comes in contact with wafers, such as Teflon®
cassettes. They are found in baskets in each room of the lab. You should put on
a fresh pair of these gloves, over your surgical gloves, each time you handle
contamination-sensitive equipment or samples (such as silicon wafers, Teflon®
wafer carriers, internal equipment parts).
III.
Stock
Safety & Chemical Stock
Before proceeding
into the clean room, note that there are certain stock items available in this
area for your convenience such as bottle carriers and chemicals. Many commonly
used chemicals, such as acetone, sulfuric acid and buffered hydrofluoric acid,
are kept in metal chemical cabinets in the lobby. There is a list of chemicals
and their locations posted on the right side of those cabinets, near the
gloves.
There is also a
complete list of chemicals and lab materials on the Wand under the category Materials
and Chemicals. If you need a certain chemical, first check the
immediate area in which you are working and in the Old Lab for open bottles. If
none are to be found, check the list on the wand to see if it is a stock item.
If so, chances are you will find it in one of the cabinets. If not, contact the
Office for more information on obtaining the item.
Transporting
Chemicals Safely
When bringing
chemicals into the lab, you must use the safety bottle carriers provided in the
lobby. When you are finished with the carriers, PLEASE return them to the lobby
so that they will be available for others to use. Also, be sure to check your
immediate work area and the Old Lab for open bottles of the desired chemical
before bringing a new bottle into the lab.
IV.
Entering the Lab
Sticky
Mats
As you enter the
lab you will see a mat on the floor known as a sticky mat, and it is just that.
Its purpose is to remove particles from the bottom of your shoe covers before
entering the lab, so be sure to step on it firmly. These mats have many layers.
If you notice that the mat is dirty and has lost its stickiness, please peel
off the top layer to expose a new sticky surface underneath. Note that the
layers are numbered in a corner to prevent your accidentally peeling off more
than one. The old, used layer can be discarded in the trashcan in GL1.
Lab
Construction - Service Chases
One of the first
things you may notice about the lab’s construction is its modularity. This type
of construction allows for a good deal of flexibility. Especially useful is
this design’s ability to isolate the utilities from the clean areas of the lab.
You will notice that each lab room is separated from the other by what is known
as a 'service chase'. These areas house the dirty equipment (mechanical
pumps, cylinders) and allow technicians easy access to them. Students are not
permitted to enter the service chases unless there is an emergency. Circuit
breakers are also located in the service chases and you should be familiar with
their location so that you can use them in case of electrical emergencies, such
as electrocution. There is a category on the wand called Safety, Trouble
& Prevention which you should consult should an emergency situation
arise while you are in the lab and staff is not immediately available. It
contains instructions and emergency phone numbers with which to contact staff.
Safety
Equipment
As you walk
through the lab, please pay particular attention to the locations of safety
showers, eyewashes, first aid stations, fire extinguishers, and emergency
exits. These will be pointed out to you during the tour. You will see that
there is safety shower, eyewash and first aid supplies directly to your
right as you enter the clean room.
Please make every
effort to be conscious of the locations of safety equipment at all times when
you are in the lab. Know where the phones are located - each posts emergency
numbers. When you enter a room, make a mental note of the nearest eyewash,
safety shower, fire extinguisher, phone and emergency exit. This knowledge
could save you precious seconds if an emergency should arise.
The Microlab has fully functional
telephone sets located in the lobby, AN1, AN3, the Old Lab, and GL3. You can
call most staff members directly at the numbers posted by each set. Calling
staff is not a substitute for filing a faults report on the wand. Another
common use is to call extensions 10 or 12 to request supplies. The phones can
also be used to page other labmembers inside the Microlab. Press the button
labeled ITCM, then the button labeled Lab Page and talk. The phones may be used
to make outside calls limited to the Bay Area. Out of courtesy to other
labmembers, please limit your use to short calls. If you must engage in a long
conversation, leave the lab and make your call on another telephone system.
Intercom
(squawk) boxes are located in 432, 432D, GL1, GL2, Gl3, GL4, R1, R2, Y1, Y2, Y3
(two), and V1. Pressing the button alerts a phone attendant in the Microlab
Office. The phone attendant can transfer you to a staff member, do an All Call
page for staff members not at their desks, or relay your request for supplies.
General Labs - GL
The first rooms you encounter on the left as you enter are the G
or general use labs, GL1, GL2 and GL3. These labs can be used by students
working in specialized areas such as sensors, III-V compounds and/or
superconductors. Storage space for students using these labs is available in
these rooms as well as the storage room located directly on the right as you
enter the clean room.
V. Old
Lab - Rooms 432, 432A, 432B, 432C, 432D
Central Area (432)
On the right side
of the lab, through the double doors, is the ‘Old Lab’. Please note that this
is not a class-100 area, and special precautions should be taken when handling
contamination-sensitive materials. Such items should be exposed only fewer than
one of the four laminar flow hoods in this area. Directly to your right as you
enter the old lab is a door leading to a storage area. This area is restricted,
except in case of an emergency because it provides an exit. There is a variety
of equipment located here, including a number of evaporation systems. A phone
is available by the door as you enter the Old Lab. There is also a room in the
old lab where you will clean your new lab gear, dispose of chemical waste, and
carry out non-standard chemical
processes. This room is known as the Chem Room.
Sink432a Room (432A)
This room contains a hooded sink (sink432a), chemical storage
cabinets, a refrigerator for storing perishable chemicals and the ASML laser.
Note that there is a safety shower and eyewash in this room.
Room 432b (432B)
This room contains the yellow metal Chemical Disposal Cabinet and
various processing equipment.
Chem Room (432C)
The chem room contains a hooded sink, a regular sink, hotplate, a
sonic bath, miscellaneous glassware, and chemicals for general use. This is the
room where empty chemical bottles are rinsed before being discarded (see Chemical
Waste Disposal below). Sink432C has an aspirator for
water-miscible solvents and acid disposal. Note the safety shower
and eyewash next to the hooded sink. Also, there is an emergency exit
available from the chem room through 432D (the disco room).
General Use Chemicals
Next to the black sink there is a cabinet containing dry chemicals
for general use. Please, be sure to use a clean spatula when removing dry
chemical from a jar. Never put any reagent back into a jar once removed,
cap the jar tightly, and put it back in its correct location when you are
finished with it.
Chemical Waste Disposal
When you have
emptied a chemical bottle, plastic or glass, bring it to the chem room (using
a safety carrier, if the bottle is glass) and rinse it thoroughly 3
times. Bottles that contained acetone, methanol, 2-propanol (IPA), ethanol,
photoresist developers, and floor and lab cleaners should be rinsed in the
black sink by the door. Bottles, which contained acids or chlorinated solvents,
should be rinsed at sink432c (432C, white sink). Sink432c is a certified fume
hood and will prevent exposure to volatile compounds while rinsing bottles. If
you are unsure which sink to use, use sink432c. Wear a face shield and chemical
resistant gloves while doing so. Once it has been rinsed 3 times, scratch the
label with a can opener, which can be found attached to the cabinet near the
black sink. Scratching the label indicates that the bottle has been properly
rinsed. Clean glass bottles go in the trashcan located directly outside
the chem room door. Clean plastic bottles, which have been emptied of
BHF or peroxide, go in the can located farther down along the same wall.
Bottles, which have been emptied, of silicon etch, which is mixed by lab staff,
should be rinsed but not discarded. Place the properly rinsed bottles in the
white chemical cabinet to the right of sink432c.
Mixing Chemicals Can Be Dangerous!
It is imperative that chemicals be discarded properly. Mixing
chemicals carelessly can be extremely dangerous. Acids and solvents should
never be mixed together in the same container as this is a potentially
explosive reaction. Acids and water-miscible solvents such as alcohol and
acetone are disposed of by aspirating them down the drain of the hood/sink. The
aspirator will suck liquid up through the tube and mix it with large volumes of
fresh water before sending it down the drain. When you are finished with an
acid or water-miscible solvent, simply turn on the aspirator and plenum flush
(which produces the water to dilute the chemical) and aspirate the acid
directly from its container by putting in the aspirator tube.
Undiluted, non-water-miscible and chlorinated solvents, such as TCA,
photoresist or chloro-benzene should NEVER be aspirated. Disposal
of solvents in this manner is not only an environ-mental threat, it will also
damage the building's plumbing. Photoresist and chlorobenzene should be saved
for reuse. Please, see Marilyn Kushner to recycle photoresist (chlorobenzene
should be saved in a clean, capped bottle for personal reuse). Photoresist,
which is significantly diluted with acetone, can be poured into the plastic
organic waste bottle at sink432c in the chem room (to the right rear of the
fume hood). A waste bottle for used PRS-3000 photoresist stripper is also
located at this sink.
If you need to dispose of a chemical,
which can neither be aspirated nor recycled, the waste should be placed in a
loosely capped plastic bottle with a label clearly identifying the contents.
The bottle should be placed in the yellow cabinet along the back wall of Room
432B in the old lab. You must fill out the Hazardous Waste Manifest
Sheet located on the top of the yellow cabinet with the following information:
1. Your login name
2.
Material identification and descriptive information
Place the ID number from the Manifest Sheet on the waste package
(write on labels are provided if needed). These bottles are picked up and
disposed of by Environment Health and Safety. If the waste storage area is
full, notify the Office and some will be removed to make room for new bottles.
|
Chemical
Disposal Methods |
|
|
Aspiration |
Recycle |
|
Acids HF HCl H2SO4 Water Miscible Solvents Methanol Propanol Acetone Organics Photoresist
in Developer |
Water Immiscible/Halogenated Organics Chlorobenzene Photoresist Photoresist
diluted with Acetone |
Chemical Spills
All spills, whether at a sink or work surface, must be cleaned up
at once. Leave work areas as you would like to find them. Reminder:
water and acid/HF look the same.
DISCO Room (432D)
Right next to the chem room through the door, is a room containing
a DISCO automatic dicing saw. On the other side of this room is a door leading
to a technicians' storage area and there is an emergency exit through
there.
Miscellaneous
Supplies
Against the back wall of the old lab, by the door to the chem room
is a cabinet with miscellaneous supplies, such as razor blades, tape, etc.,
which are available to all users while they are working in the lab. Teri-towels
can be found at sink432D and sink432c; techni-cloths (lint-free wipes) are
stocked in the newer parts of the Microlab.
Glassware: All glassware must be washed and dried under the red lamps. Sink
decks or sink fume hoods are not the place to store or leave wet glassware to
dry.
VI.
New Lab - Yellow Rooms Y1, Y2 & Y3
Y1
Continuing down the hallway past the GL rooms, we come to the
yellow rooms on the left. These rooms have filters on all light sources to
allow photolithographic processes to be carried out here. Y1 contains two
manual mask aligners (the Quintel and the Canon), a wet sink, a photoresist
spinner, a microscope with filtered light source, and bake ovens. Drawers are
available for storage of personal photoresist dropper bottles, which should be
labeled with your name and date.
Y2
Y2 contains a wet sink, a spin-rinse/dryer, svgdev, and an
automated photoresist coat track, svgcoat. There is also a large convection
oven for hard baking photoresist after exposure and development and a general
use microscope with filtered light source.
Y3 - Stepper Room
Adjacent to Y2 is Y3, or the Stepper Room, which houses two GCA
wafer steppers (GCAWS2 and GCAWS6). Masks which will be used in the steppers
may be stored here. This room also houses the flipchip.
VII. VLSI
Equipment
The VLSI area,
located just beyond the Yellow rooms, contains the Tylan/Tystar furnaces;
Technics & Matrix plasma systems for nitride etching and photoresist
ashing; four Lam plasma etchers for oxide, polysilicon, and nitride; a CPA
metal sputtering system; an STS deep silicon etcher; and four wet process
stations (see Chapter 2.7 for more information on sink usage in this area).
Face shields, aprons & chemical resistant gloves MUST be
worn at all times when working at the wet sinks!
Service Chase
Behind the
furnaces is a large area (Tystar service chase) which is accessible to staff
only, except in case of an emergency or chemical spill. There is a safety
shower and an emergency exit located in this area.
The most
contamination sensitive processing is performed in the VLSI area of the lab.
Note and be certain to observe the restriction posted at the entrance to the
VLSI area: No gold is allowed in the VLSI area.
The Microlab
typically provides contamination control by defining and limiting materials
that can be processed in each tool. Due to the extreme concern with gold
contamination, this additional restriction is imposed on the VLSI area to
minimize the chance of even accidental gold contamination of any tools in the
VLSI area.
VIII.
Analytical Areas, GL4, Red Rooms
AN1
In this area are a safety shower, eyewash station,
emergency exit, and phone for making local or on-campus calls.
AN2
Opposite Y3 is an area containing some more analytical equipment,
including: a 4-point probe resistivity meter, a SOPRA ellipsometer, a
profilometer, and a Nanospec AFT film thickness-measuring system.
AN3
Further along the hall across from the VLSI area is a set of
analytical equipment: the Vickers and Nanoline line width measurement systems;
a surface charge analyzer; a Nanospec/DUV Micro-spectrophotometer; an
ellipsometer; and an IV probe station with curve tracer.
There is also a phone in this area where you can make local
(510-area code) or on-campus calls. There is a door by the probe station which
leads to the Tylan service chase. Labmembers are not permitted to enter this
area except in case of emergency -- to use the safety shower or leave via the
emergency exit.
GL4
GL4 is a room dedicated to the advanced photolithography. This
area contains the ASML DUV Stepper, the 6” SVG coater and developer tracks, and
the UV Scope.
Red Rooms
Behind the SEM is a door leading to the Red rooms, which contain
all equipment necessary for mask making: pattern generator, automatic mask
developing systems, and a small wet sink. In addition, the CD-SEM is located in
R2 and the Tencor Flexus in R1.
IX.
Computer Usage: the Wand
You will notice during the tour that
each room in the lab has one or more computer terminals, there for your
convenience in accessing the wand. Following is a brief introduction to using
the wand, the menu-driven system which allows you to do things such as
enable/disable equipment, check equipment status, make lab notes, reserve time
on a given piece of equipment, report problems or simply make comments. Other
things available through the wand, which you will find useful, include
inventory lists.
Wand Description
The wand is the lab control computer program.
The wand displays
two main menus, entitled CATEGORIES and TASKS, located next to
each other on the top half of the screen. A different set of Tasks is
associated with each item in the Category menu. In order to make a selection
from one of these menus, you must first indicate which one you are selecting
from. The current menu is marked by a border, which you can toggle
between the menus by hitting the space bar. Typing the letter next to a menu
entry will select that item from the current menu.
All commands
executed with your wand (except sign out) involve making a selection from the
TASKS menu. Thus, to perform a new task, the TASKS menu must be the current
menu (it must have the border around it). Typing the key next to the task you
want to execute immediately runs the program to perform the task. Some
tasks need some more information: these programs will prompt you for
information needed on the bottom line of the screen.
You will find that once you begin using the wand, its menu system
makes its use simple and self-explanatory. It is suggested that, once you have
an account, you log in and explore all the Categories and Tasks menus. Please
do not hesitate to ask questions of your fellow students or staff.
Equipment
Maintenance and the Computer
The cooperation of all students is required to keep our equipment
up and running. The computer supplies an easy and efficient way of keeping
track of equipment problem status and of notifying the technician-in-charge
when trouble arises with a given machine. Please, refer to the orientation
handout for further information on the computer and equipment.
Signing Out of the Lab
To sign out of
the lab, first make sure that
you have selected the category for signing out (it is a separate
category, s). The system will sign you out, take away your wand, and let
you know if you inadvertently left any equipment enabled. If you did, you are
given the option of returning to your wand to disable that equipment. In
special cases, you may actually wish to leave equipment activated after you
leave the lab, so you may choose the yes (y) option when asked, Do
you really wish to sign out?
X.
Clean Room Procedures and Policies
The following are established
procedures and policies which must be observed when working in the Microfabrication
Facility. Failure to do so puts everyone's work, including your own, at risk of
contamination. Please proceed accordingly.
General
Information
The following items are considered contamination
sensitive:
►
Wafers or silicon samples;
►
All equipment which comes into contact with wafers: tweezers,
Teflon®;
►
and/or polypropylene cassettes, certain machine parts.
These items are handled only while wearing a fresh pair of clear
plastic gloves. They should never be placed directly on any table surface, but
only on Techni-cloths 100, and should always remain under HEPA filters.
Cleaning New Lab
Gear
When you receive your new lab equipment, such as wafer boxes with
cassettes, tweezers, etc., you will want to clean them. There is an established
procedure for doing this. See Chapter 2.1 of the Lab Manuals (on the wand or in
hard copy by the terminal in the reception area) and follow directions
carefully. All cleaning is done in the laminar flow hood of the chem room.
Tweezers
These are to be used only for moving your wafers into and out of
polypropylene or Teflon® cassettes. Do not use them to immerse your
wafers into solutions of any kind. They will contaminate the solution and you
may wind up depositing metal ions on your own and other students' wafers. You
should use the Teflon® cassette provided if working at a wet sink,
or obtain one if you are working in the chem room. Special holders are
available if a Teflon® cassette is not appropriate (e.g., if you
only want to immerse a piece of a wafer or one wafer into a beaker). If you
must immerse tweezers into a solution, only Teflon® tweezers are
permitted, but you should note that these are clumsy to use.
You may want to maintain a separate pair of tweezers for handling
samples with photoresist.
Gloves
Poly-d gloves are available in every room of the lab. A fresh pair
should be put on each time you handle your wafers, or anything that will touch
wafers, including Teflon® cassettes used in the sinks, and machine
parts that will contact wafers.
Wet Sinks - VLSI
Sink 6 is for clean wafers only, i.e., wafers which have
been previously cleaned of residual photoresist and/or metal. Wafers may
be placed in the Tylan furnaces only after being cleaned in Sink 6.
Wafers having just been stripped of photoresist or metal must first
be cleaned in Sink 8, then cleaned again in Sink6 before going into the
furnaces. (See Chapter 5.0 – Tystar/Tylan Furnaces Overview).
Never mix the Teflon® or black Stat-Pro 1008 cassettes
among the different sinks. This will lead to photoresist and/or metal
contamination of the clean sink. Each cassette and handle is embossed with
either MOS or MEMS for use in this area. Also, the VLSI sink
cassettes should not be placed directly on any table surface. Always use a
Techni-cloth as a clean surface for any contamination sensitive item.
Never immerse stainless steel tweezers in any solution (see
above).
Rinse wafers to >10 megohm-cm at sink6 before transferring them
to the spin-rinse dryer (SRD).
Wafer Handling
Always wear fresh clear poly-d gloves when handling your wafers.
Do not allow your gloves to touch your face.
Never talk or breathe over your wafers. There is a great tendency
to do this when working with the microscopes. Saliva is the most common
contaminant in the lab.
Isolate wafers with photoresist from your clean wafers. You may
want to dedicate a separate box to wafers with photoresist, or at least one
side of a box. Use separate tweezers to handle 'clean' wafers and those with
photoresist.
Never lay your wafers down on a table surface. Your wafers should
contact only clean cassettes or lab equipment. Wafers should be exposed only
under HEPA filters.
Work Storage
Ask the process staff (email processtaff@silicon) for
drawer space in the rooms you use most often. Alternately, you may store labeled
closed boxes in the walk-in closet on the right next to the entrance to the
clean area. Always store your parts after you have completed your work for the
day.
Space: The Microlab has limited space for lab member storage. Members
are asked to expediently clean out drawers and then remove their nametags and
marker tape from their drawers when they are no longer needed. Send e-mail to marilyn@silicon
so these drawers can be reassigned.
TABLE TOPS AND WORK SURFACES ARE NOT FOR LAB MEMBER STORAGE!
K. Voros
Rev. 04 – 5/05
Teflon® is
a registered trademark of DuPont.