SSEL Instructional Lab Orientation
The object of the laboratory sessions is the fabrication of n-channel self-aligned Si MOSFET’s with polycrystalline Si gates. This process has been designed to allow all but a very few steps to be done completely in the instructional laboratory by small groups of EECS 423 students. This particular process uses moderately heavily doped, p-type, (100) orientation Si wafers in a four-mask process. The source/drain regions and the poly-Si are doped in a self-aligned diffusion cycle. The resulting transistors are not quite state-of-the-art, but are, in fact, very good transistors which yield virtually textbook characteristics and are amenable to fairly detailed analysis.
There are nine cleanroom lab sessions planned for device fabrication and two for testing. Delays for various possible reasons might occur. Each student will have one Si device wafer and monitor wafers to be shared with the group in the same session. We will go over each lab in details in class the Monday before it starts. Before each lab session, you should familiarize yourself with the operations to be done and have a clear picture in mind of why each operation is required and why they occur in the stated order. The processes, which will be used, are fairly reliable, but most are irreversible. At most stages, a real mistake could mean that your devices are destroyed. At any stage, if you are unsure about what you are doing ask the Instructional Laboratory Supervisor in the Lab. This can prevent loss of your wafers or even personal injury.
The air in the cleanroom is filtered by High Efficiency Particulate Air (HEPA) filters. The SSEL Instructional Lab is a class 1000 cleanroom. Class 1000 means there are <1000 particles that are 0.5 µm in size per ft3 (a typical unfiltered room has >200000 particles). There are many different chemicals in the cleanroom. It is important that you obey all the safety rules when handling these chemicals. Your Instructional Laboratory Supervisor will show you all the proper procedures and safety equipment when chemicals are used. Additional information related to safety, first aid, fire and explosion data for hazardous chemicals can be found in Material Safety Data Sheet (MSDS).
In general, this laboratory is probably safer than your high school or freshman chemistry lab. However, you will be working with strong acids and bases, organic solvents, sources of ultraviolet light, very high temperature furnaces, and lasers. Reasonable behavior on the part of everyone will insure a very safe environment. Failure to follow the laboratory safety rules can very easily result in serious injury to you and others; therefore, serious safety violations will result in ejection from this class. A variety of rules and policies for students using the SSEL Instructional Laboratory are described below. This list of rules is not necessarily all-inclusive; ask questions when in doubt. Disciplinary action regarding rule infractions is at the discretion of the Instructional Laboratory Supervisor, in consultation with Prof. Pang if appropriate.
General Procedures
- you may not enter the lab, under any circumstances, without the Instructional Laboratory Supervisor.
- do not work alone at anytime in this lab.
- when entering the lab it is mandatory to LOG In and OUT.
- contact lenses are not permitted.
- absolutely no food or drink.
- no personal items are to be brought into the cleanroom or gowning area. You can leave your personal belongings outside the gowning area.
- do not use equipment or chemicals without proper training.
- do not remove or bring equipment or chemicals into the lab without permission from the Instructional Laboratory Supervisor.
- use only cleanroom compatible paper or notebooks and pens or markers.
- all spills, glass breakage, etc. should be reported immediately to the Instructional Laboratory Supervisor .
- all users are responsible for cleaning up their work areas when done.
Equipment/Materials
- all users must be trained by the Instructional Laboratory Supervisor and authorized to use equipment.
- you must login when you begin to use each piece of equipment.
- do not change equipment or process parameters.
- wafers not being immediately processed or those are being transported from one work area to another must be stored in covered containers.
- lab wear (beakers, graduated cylinders, etc.) must be rinsed, dried and properly stored after use.
Gowning Procedures
- all users are required to wear safety glasses/goggles, booties, a lab coat, a cap, and gloves at all times.
- put on safety glasses and mask then gown from your head down.
- please remove mud and dirt from your shoes prior to entering the lab.
- change your gloves or cleanroom clothing if it becomes torn, dirty or contaminated.
Chemicals
- follow process instructions carefully.
- always wear the proper personal protection equipment when working with chemicals (solvent-resistive gloves, protective sleeves, acid aprons, face shields).
- visually inspect all safety gear before use; replace anything that is worn or damaged.
- before removing, always rinse and dry acid- and solvent-resistive gloves. Wash only the outside with DI water, and dry with wipes.
- do not taste, smell or touch any chemicals, vapors or gas.
- only use chemicals in wet processing stations.
- chemical containers must be tightly closed and returned to the proper storage location immediately after use.
- pour chemicals slowly to avoid splashes.
- never mix acids and bases - strongly exothermic reactions can occur.
- never mix acids or bases with organics - explosive reactions, formation of toxic byproducts are possible. It is especially important to remember not to use acids or bases in the photoresist developing (solvent) hood.
- remember Always Add Acid to water (AAA) - Never Add Water to acid (NAW).
- the RCA Pre-Furnace Clean hood is to be used for this procedure only.
- all beakers, graduated cylinders, etc. should be emptied, rinsed with DI water, and properly stored after use.
- treat unknown chemicals and spills as hazardous. NOTIFY the Instructional Laboratory Supervisor.
- all minor chemical spills (drips and splashes) at any acid or base station are to be wiped up immediately using DI-dampened wipes. Solvent spills can be cleaned up with a wide dampened with isopropyl alcohol (IPA). Larger spills should be brought to the attention of the Instructional Laboratory Supervisor. Dispose of used wipes in the appropriate trashcan (ACID, BASE, SOLVENT, etc.).
Waste
- acid, bases and solvent contaminated waste solids have separate disposal receptacles.
- on hoods so equipped, always run the plenum flush several cycles after disposing of liquid wastes by either aspirating or dumping into the plenum.
- on acid and base hoods, always aspirate water after aspirating wastes (does not apply to solvent hood).
- if aspirator becomes full an alarm will sound, notify the Instructional Laboratory Supervisor.
- pour NOTHING down the drain!
Emergency and Evacuation
- if a fire or gas alarm sounds or when you are told to evacuate -
evacuate the lab immediately (breakaway doors)
leave your work as is!
leave on your cleanroom clothing
proceed to designated meeting place and wait for the Instructional Laboratory Supervisor
do not leave until the Instructional Laboratory Supervisor authorizes you to do so
- know the location of emergency eye wash stations, emergency showers, first aid kits, fire extinguishers, and pull stations.
- if you receive a chemical splash, IMMEDIATELY begin flushing the affected area with plenty of water. SPEED IS VITAL.
- if chemicals come in contact with your eyes -
rinse at emergency eye wash station for 15 min while raising upper and lower lids
notify the Instructional Laboratory Supervisor
GET MEDICAL ATTENTION as quickly as possible.
- if chemicals (except HF) come in contact with your skin -
remove contaminated clothing
flush with water for at least 15 min.
notify the Instructional Laboratory Supervisor
GET MEDICAL ATTENTION as quickly as possible.
- if HF or HF mixtures come in contact with your skin -
remove contaminated clothing
flush with water for at least 25 min.
apply "HF creme" if available
notify the Instructional Laboratory Supervisor
GET MEDICAL ATTENTION as quickly as possible.
- know the meaning of chemical labels (Low number for safer chemical).
number designations 0 - negligible
1 - minor
2 - dangerous
3 - serious
4 – severe