Laboratory for Advanced Materials Processing

___________________________________________________________________________________________                 

Adapted from the LSU CADM safety training manual

Introduction

As part of the user community, cleanroom workers are expected to have already received radiation safety, general chemical safety training, and cleanroom etiquette training. This guide will identify the various chemical hazards and how to deal with them, what to do in an emergency situation, how to conduct experiments, and will provide some basic guidelines for general chemical use, storage and hazards. The guide is intended to serve as an initial introduction to some important safety issues. Specific information pertaining to the LAMP research facility is covered in the overall LAMP safety guide.

This guide also serves as a portion of the LAMP right-to-know communication program. Right-to-know laws were implemented by OSHA and although universities are strictly exempt from such laws, it is LAMP policy to adhere to these regulations to the extent possible. The right-to-know gives workers access to information on the hazards to which they can reasonably be expected to be exposed. This information is contained in the MSDS.

As a University research facility, LAMP  is not nearly as stringent as commercial facilities. The benefit is that you have more flexibility in trying out new processes. However, the flipside is that each user must take special care and responsibility for their actions while working in the lab. Cleanrooms are controlled environments in which each action is controlled and well thought out. Toxic chemicals make you sick if you breath, swallow or touch them. Corrosive chemicals burn or damage human skin, eyes, nose or lungs and dissolve metal. Flammable chemicals burn easily. These are most frequently typified by organic solvents. Solvents also remove protective oils or lubricants on the surface of our skin. Oxidizing chemicals produce oxygen when mixed with organics or solvents which create a fire hazard. Such compounds are known as oxidizers or oxidants and are irritating to the skin, eyes, nose and lungs. An acid is a chemical which corrodes metal. Etchants are typically acids. All acids burn the skin, eyes, nose and respiratory tract if you come into contact with them. An alkali, also known as base is a caustic water-soluble substance which has the capability to burn the eyes, skin and respiratory tract. It is used to neutralize acids. An asphyxiant is a gas which may be relatively non-toxic (such as nitrogen) but may cause fainting or even death if it replaces the available oxygen in the air. BOE stands for buffered oxide etch which contains ammonium fluoride as a buffering agent mixed with hydrofluoric acid.

A carcinogen is a compound which is known to produce cancer. Read MSDS sheets completely when you receive a new chemical. Under Biological effects, suspect carcinogens and mutagens will be listed. A caustic is a base (alkali) which will burn the eyes, skin or respiratory tract. Most bases (alkali) are called caustic. A ceiling standard is a government dictated value which specifies the maximum exposure limit of a chemical for a given period of time (normally 8 hours). Combustible substances are those that will burn above 1000F. Corrosives are materials which attack metal and will burn human skin. Both acids and bases are corrosive. A Cryogen is a substance at very low temperature which will freeze your skin if you touch it. Danger is the highest degree of hazard warning. The Flash Point is the temperature at which a liquid or volatile will give off enough vapor to start a fire if an ignition source is present. Hazard Communication is dictated by OSHA (the occupational safety and health administration) which requires workers to be informed of their workplace hazards. A large part of this is the MSDS (Material Safety Data Sheet). Hazardous implies that using a particular substance carries with it some risk. IDLH Concentration (immediately dangerous to life or health) is the maximum chemical concentration exposure in 30 minutes which does not produce life-threatening effects.

Incompatible describes chemicals which react dangerously when mixed or used together. When one reads an MSDS sheet, the mg/m3 is that concentration of a chemical that is generally used to determine the concentration of a solid in air. The MSDS is the material safety data sheet which is supplied by the manufacturer. It supplied information regarding the hazards of a particular material and is mandated by OSHA as part of the hazard communications program. When a chemical is ordered for use in LAMP, the MSDS is mandatory. These sheets can be downloaded or can be retrieved from the notebook located in the LAMP annex. Odor Threshold is the smallest concentration of a chemical detectable by the majority of humans. An oxidizer is a material which either releases oxygen by itself or when mixed with organics or solvents. This oxygen is combustible and can present a fire hazard. The PEL is the permissible exposure limit. This is the maximum legally allowed exposure to a hazardous substance in an 8 hour time limit (normally). Personal Protective Equipment (PPE) are those items designed to protect individuals working with hazards. They may include gloves, face shields, safety glasses. respirators, ear plugs and steel-toed shoes. A poison is a substance which may cause adverse health effects when eaten, inhaled or absorbed through the skin.

PPM (parts per million) is a unit of measure most frequently associated with the measurement of chemicals in air and water. The respiratory system includes the mouth, nose throat, lung passages and lungs, and is the usual target organ for chemicals which are suspended in the air in which we breathe. A solvent is a liquid which is capable of dissolving another substance. Common solvents in the LAMP include acetone and ethanol. The TLV (Threshold limit value) is the highest recommended amount of human exposure for a given compound, without experiencing any deleterious effect. A toxic substance is one capable of causing injury, illness or health effects. A warning is used to describe an intermediate degree of hazard for a chemical. Warning properties are those properties of a chemical which allow you to detect its presence such as odor (i.e. ozone), or eye or skin irritation.

Major classes of chemicals:

Acids commonly used include acetic, hydrochloric, sulfuric, nitric, hydrofluoric and phosphoric. All acids are corrosive and will burn skin and eyes upon direct contact. Mists of these acids will irritate the eyes, nose and throat. You must wear eye protection, proper gloves, and leather shoes when you work with acids. When pouring acids or handling containers or new or waste acids, you must also wear a face shield and apron. Ideally, you should never hand carry chemicals - always use an acid bucket or a cart. Hydrofluoric acid (HF) and mixtures like BOE (Buffered Oxide Etch) present special problems. They look like water and if they fall on your skin, you may not feel anything, but HF will continue to burn until it reaches the bone. If you suspect you have spilled HF or other corrosive material, flush with water for 15 minutes and inform University safety immediately.

Remember not to store acids with solvents or strong bases. Be familiar with all incompatibilities for the chemical or mixture you are using. Read the MSDS documentation, so that there are no surprises. 

Organic solvents are used to dissolve oils, fats and grease or to degrease metals. They are also contained in photoresists and developers. Solvents can evaporate quickly and can represent a fire or respiratory hazards and can be readily absorbed through the skin. All solvent use should be restricted to the fume hood and protective solvent proof gloves. Phenol, like HF has a mild anesthetic-like effect, so you can't feel if you have been exposed. Take special precautions. All flammable solvents must be stored in flammable storage cabinets and be properly labeled. Oxidizers are materials which decompose or react rapidly and release oxygen. Such materials can cause fires or explosions. Always wear gloves, eye protection and leather shoes when working with oxidizers (such as peroxide). If exposed, flush affected area for 15 minutes with water. Never store oxidizers with flammable materials or solvents. Cryogenics such as liquid nitrogen and liquid helium can cause explosion, frostbite or the production of asphyxiating gases if improperly handled, Do not flush area with water if exposed - allow affected area to warm. If spilled on foot, do not walk - call for help. This is why we have a buddy system. When handling wear insulated gloves, safety glasses and face shield.

Inert gases such as nitrogen and argon can become dangerous in high concentrations in areas where there is inadequate ventilation. Always make sure that nitrogen to the cleanroom is well regulated and not left unattended. Emergency phone numbers are posted on the inside of the main lab door.

General Safety Notes:

• Remember to ensure the fume hood is turned on before you begin any chemical work in the cleanroomm, even if you are not planning to actively work with chemicals.
• No chemicals are to be flushed down the sink. They will be collected and properly disposed of.
• Never wear open-toed shoes in the cleanroom.
• Always use thick gloves when handling acids (usually neoprene).
• Chemicals should never be hand carried. Always use the hand carts provided or an acid bucket.
• Label all containers clearly and correctly using the NFPA ratings.
• If unsure about a process or procedure, ask your supervisor.
• Most importantly, think about the consequences of each of your actions. All movement should be deliberate and well thought out and characterized.
• Before beginning a new procedure, always make a dry run first. It is important to identify any bottlenecks or potential dangers.
• When using a new chemical, you must read the MSDS first.
• Stop unsafe practices immediately. Each person should have the right to question a procedure that he/she considers inherently unsafe.
• Discuss new procedures with others to make sure you have not overlooked a potential hazard.
• Write out the protective equipment list you will need for each procedure and then ascertain that you have all of the required equipment before proceeding.
• If you are pressed for time, do not begin a new procedure. It is better to wait until adequate time can be devoted to the task. Haste is a prescription for disaster in a chemical laboratory.
• Schedule your activities well in advance and make certain to leave a margin of safety for unforeseen delays. An equipment reservation book is available on the small table outside the cleanroom entrance.
• If you are unsure about a process or the making of a particular solution, ask your supervisor.
• Do not use water near electrical power and be aware of thermal hazards in the cleanroom such as hotplates and ovens.
• Always turn on the fume hood or wet sink ventilation before opening a chemical.
• Make sure the fume hood or wet sink is clear of debris and that there are no chemicals stored in the fume hood. Such chemicals must be removed before beginning your procedures, as other chemicals may not be compatible with your chemicals.
• If there are spills in the fume hood, make sure they are picked up before you begin your task. Use pH paper to check and identify the nature of the spill, then proceed accordingly to clean up the spill before proceeding.
• Remember that wind currents (i.e. other people walking by etc) can adversely affect the flow in a fume hood.
• Use an apron and safety glasses when working with acids as well as heavy neoprene gloves.
• Use only the amount required. Large quantities are cumbersome. This handling difficulty significantly increases the risk for spills.
• Always use face shields or safety glasses and an apron when working with acids.
• Be aware of hot plates and ovens in areas adjacent to where you are working with solvents. These can be potential fire or explosion hazards.
• Always leave your work area clean, pick up spills immediately. Poor housekeeping practices increase the risk for injury or damage.!

NFPA Labeling

The blue diamond gives information on personnel safety with a rating system from 0 to 4. 0 means there is no hazard, 1- slight hazard, 2- protective equipment should be worn, 3- do not expose any body surface and 4 - any exposure could be life-threatening. These numbers do not identify whether the hazard is contact or respiratory etc. This information must be obtained from the MSDS which will also identify the appropriate personnel protective equipment. Most organic substances will burn. Generally flammability is related to the flashpoint of the material which is in turn related to the vapor pressure of the material. Many solvents will readily evaporate, such that the concentration in air rapidly rises and will burn, ignite or explode when exposed to an ignition source. Once again, a rating of 0 - 4 is used for the red block. Substances such as H2O will not burn and have a flammability rating of 0. Those chemicals which have a flashpoint above 2000F. have a flammability index of 1. If the flashpoint is >1000F. but less than 2000F., then the chemical is given a rating of 2. Substances which are volatile or even explosive under most conditions and have flashpoints below 1000F. receive a rating of 3. Finally those chemicals whose flashpoints are below 740F. (i.e. room temperature) are given a rating of 4. Such materials must be stored with extreme caution and care must be used when handling these materials.

Reactivity of compounds can also be classified in an analogous manner. Using a system from 0 to 4, the stability of chemicals may be classified. In particular, changes in pressure or temperature may have serious implications for many chemicals. This data is reflected in the yellow diamond of the NFPA symbol.

Compounds such as NaCl are stable and will carry a rating of 0. Those compounds which may become unstable with elevated temperature or pressure will have a rating of 1. Those substances which have a slight potential to become unstable even at normal temperature and pressures will have a rating of 2. Such chemicals can undergo potentially violent reactions. A rating of 3 indicates that the materials potentially explosive. Heat, shock waves or water (if it is incompatible) may detonate such materials. Persons working with materials with a reactivity level of 4 must know where such materials are located and must be willing to vacate the premises in which these materials are stored if there is a significant increase in heat or there is a fire.

Flammability and reactivity data are essential for the proper control of a fire. This information is contained in the MSDS supplied by the individual manufacturer.

The final diamond in the NFPA label is white and identifies materials, or other compounds for which the labeled chemical has an incompatibility. the W with a line through it tells us that this particular chemical is incompatible with water. Care must be taken not to wet such a material. This is also important in fire-fighting where water is the most common extinguishing medium,. Sodium metal is one compound which is not compatible with water. Other common symbols include OX for strong oxidizer incompatibility and ACID for this incompatibility.

Since it is difficult to write several compounds or instructions in the white incompatibility block, it is necessary to make a list of all incompatible materials before working with a new chemical. Once again this information is contained in the material safety data sheets. Each person working with a chemical is responsible for reading and understanding the material safety data sheet.

Materials ready for disposal must be properly labeled with the NFPA ratings and the contents of the container clearly identified. All chemicals must be labeled when used at the LAMP facility. Labeling of chemicals is always essential. Labels prevent accidents by insuring that proper conditions are always met and that there are no incompatibilities.

Gases

Currently LAMP uses a variety of gases. You can view all the MSDS for these gases by clicking here. Some of these gases are highly toxic (tungsten hexafluoride) or highly ignitive (silane). Make sure to review the safety and emergency procedure regarding the use of gases in LAMP.

Other Hazards

Most of the chemical problems have been addressed. Sometimes there are combination problems. The use of unattended hot plates (especially if not programmable) may cause injury or burns if not attended. These types of operations are best accomplished in a fume hood if possible.

Also the addition of more people to the cleanroom roster creates potentially more problems. Peripheral vision is limited and can pose a significant risk in a crowded environment.

A cart is available for the disposal of used chemicals. No chemical may be placed on this cart without being properly labeled. As part of the university community, LAMP has a responsibility for each chemical from "the womb to the tomb". Mis-labeling or lack of labeling of Chemicals used in the cleanroom significantly increases the cost of disposal and may lead to the forfeit of cleanroom privileges.