Semiconductor Lab Safety Engineered Safety'''by Design

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Semiconductor Lab Safety (Engineered Safety...by
Design)

• MatE/EE129

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OBJECTIVE

• 1. Understand Relative Risk -- How much safety
  would you like?
• 2. Statistics -- The S/C Record
• 3. Prepare for Accidents-- Avoiding, Joint
  Probabilities, PPE
• 4. Knowing your work-place-- Chemical Types and
  Effects-- MSDS, Labels and Workstation Signs
• 5. What to do in an Emergency -- Buddy System

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RISK

• Dangerous Activities
• Drive to work
• Cross the street
• Fly an airplane
• What Else?
• What is RISK in these activities?

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S/C Industry Record

• Overall record of Semiconductor Industry is good
  -- despite the risks
• Technical environment
• Trained/Educated People
• Money to do things right (10-20)
• (Similar to your car?)

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? COMPLETELY SAFE ?

• What is Completely Safe?
• Can it be achieved?
• ? Safer than all the other dangerous things you
  do?

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Achieving Safety

• How do we achieve safe work practice?
• Real Safety Achieved through
• Engineered Procedures
• Personal Protective Equipment
• Training

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Injury Accident

• Injury accident mistakePPE failure

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Statistics -- Multiple Events

• DICE
• P(4) 1/6
• P(Two 4s) 1/6 1/6 3
• P(Three 4s) 1/6 1/6 1/6 0.5
• MISTAKE 1/1000
• PPE FAILURE 1/1000
• MISTAKE PPE FAILURE
• 1/1000 1/1000 1/1,000,000

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Engineered Safety

• Simultaneous
• 1-Mistake 1-Equipment Failure
• PRODUCES NO INJURY
• PPE IS PRIMARY PROTECTION
• Must have a way to test, know if fails
• Mistakes will eventually happen

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The Basics

• What is a Wet Lab?

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Accident Protection

• What are common causes of accidents?
• What types of accidents can happen in the Wet Lab?

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Accident Protection

• Causes of accidents
• Behavior, Hurrying, Boredom -- Repetition
• Fatigue and Stress
• Working impaired (e.g., medicine, illness, food)
• Distractions
• General Housekeeping
• Un-Trained Visitors
• Accidents can be prevented by following safe work
  practices and wearing appropriate PPE.

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Chemical Hazards-- Routes of Entry

• Contact (through skin) -- Dermal Absorption
• Eye contact
• Eating/Drinking -- Ingestion
• Through cut/needle into blood stream --
  Injection
• Breath in, mouth or nose -- Inhalation

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Physical Hazards

• Broken Glassware
• Broken Wafers -- (May shatter in spinner)
• Slips and Falls
• Wet Floors
• Transporting Chemicals (You dont !)
• Pinching, Crushing

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Types of Chemicals

• Acids
• Bases
• Solvents

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Chemicals

• Acids
• Hydrofluoric Acid (HF)
• Buffered Oxide Etch (BOE) 201 HFNH3F4H2O
• Sulfuric acid (H2SO4)
• Phosphoric acid (H3PO4)
• Nitric acid (HNO3)
• Acetic acid (CH3COOH)
• Hydrochloric acid (HCl)

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Effects of Chemical Exposure

• Acids (e.g., HCl, H2SO4, H3PO4, HNO3)
• Burning sensation felt immediately (except for
  HF)
• Rinsing with water removes the acid.

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Effects of Chemical Exposure

• HF Acid (Hydrofluoric Acid)
• Effects
• Sensation often starts with an itch
• Pain may develop in minutes, or up to hours after
  exposure
• Delayed onset of effects to skin on bones!
• Fingernail -- You wont do it twice!
• Treatment
• To treat, rinse with water and use special cream
• Seek medical attention

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Chemicals

• Bases or Caustics
• Potassium Hydroxide (KOH)
• (Developer)
• Ammonium Hydroxide (NH4OH)

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Effects of Chemical Exposure

• Bases (e.g., NH4OH, KOH)
• Feels Slippery (Makes Soap out of your skin!)
• Delay in treatment will make injury worse
• Rinsing with water removes the base

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Chemicals

• Solvents
• Photoresist
• Isopropyl Alcohol, Acetone
• Oxidizers
• Hydrogen Peroxide (H2O2)
• Nitric Acid
• Mixes
• Piranha (H2SO4 H2O2)

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Effects of Chemical Exposure

• Solvents (e.g., IPA, Acetone)
• Feels cold on skin (removes oil from skin)
• May cause dizziness, headaches, nausea
• Wear Gloves when using IPA, Acetone
• Oxidizers
• Burning sensation
• May cause bleaching of skin by removing pigment

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Emergency Procedures

• In case of chemical exposure, immediately flush
  area with cool water (? 15 min.)
• Eyewash
• Eyes must be held open for flushing to be
  effective
• Buddy can hold eyes open for injured person
• Shower
• Remove all contaminated clothing
• Cools the area and washes liquid chemical off
  affected area
• Shower is COLD! (Why?)

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Personal Protection

• NEVER start a job if you are unsure of the
  hazards, procedures, or PPE
• Always assume the worst
• Unknown liquid spills are hazardous
• Unlabelled bottles contain surprises
• USED PPE is contaminated or damaged

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Protection -- PLAN!

• ALWAYS USE THE BUDDY SYSTEM when working with
  hazardous materials
• BUDDY MUST BE IN THE WET LAB, --- either within
  sight or sound
• -- able to assist in seconds
• Exception Non-hazardous operations (e.g., wafer
  removal from ovens).

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Personal Protective EquipmentPPE

• Eye and Face Protection
• Faceshields are required when working at wet
  benches
• Faceshields protect entire face from splash

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Personal Protective EquipmentPPE

• GLOVES
• Chemical resistance is based on construction
  material
• Use special gloves for acids, bases
• Use special gloves for solvents
• Beware choosing gloves by color -- Read the label!

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Personal Protective EquipmentPPE

• GLOVES
• Leak check before each use
• Use air gun away from sinks
• Worn on outside of apron, and cuffed
• Secondary gloves (over latex gloves)
• Rinse gloves prior to removal
• Avoid touching outside of glove with bare hands
  while removing

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Personal Protective EquipmentPPE

• APRONS
• Ensure apron is clean before each use
• Apron should extend down to shoe tops
• Apron is open in back
• Wipe down apron prior to removing
• FOOT PROTECTION
• Closed-Toe work shoes
• Non-absorbent materials, no cloth

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Fire / Explosion Hazards

• Mixtures of incompatible chemicals
• Acids and Bases
• Acids and Solvents
• Mixture of an acid with water may generate
  sufficient heat to start a fire.

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Fire/Explosion Hazards

• Chemical Sinks contain electrical components
• Wet benches may be constructed of material that
  burns readily
• Example Electrical connectors mounted on
  polypropylene
• Use of flammable liquids (solvents)
• Flammable vapors can ignite with any source of
  ignition such as electrical or static sparks

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Electrical Hazards

• Shock
• Burns
• Heart Fibrillation
• Wet skin conducts electricity better

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Earthquake

• Chemicals may splash from baths
• Chemicals may fall off shelves
• Overhead objects may fall
• Chemical storage cabinets may open if not closed
  tightly
• BEFORE the earthquake occurs, IDENTIFY the safe
  place to escape
• Get into the habit of checking exits!

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Protective Devices

• Exhaust Ventilation
• Chemical baths release large amounts of hazardous
  vapor
• In case of ventilation failure, evacuate lab
• Physical Barriers
• Lids on chemical baths
• Shields around sinks
• Secondary Containment

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Evacuation

• (For Fire, Spill, Fumes, Earthquake)
• Get to Safe Area, assist others
• Call Emergency Number ( 911 ), Use Blue Light
  Phone
• Exit building by shortest route
• Always know two safe exits from lab area

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Accident Reports

• Immediately inform Lab Supervisor, T/A, or
  Instructor of the accident
• Learn from Accidents
• Review afterward
• Recall what happened, what went wrong
• Determine why accident happened
• Prevent accident from happening again

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KNOW Your Environment

• Spilled Water (?) on table/sink ?
• Dont share workstation
• Clean up after yourself -- Housekeeping
• Know what hazards are present
• (MSDS) Material Safety Data Sheet

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Material Safety Data Sheets

• TLV - Threshold limit value. Airborne conc. day
  after day
• PEL - Permissible exposure limit set by OSHA
• STEL - Short term exposure limit 15 minutes, not
  more than 4 times a day
• LD50 - Lethal Dose 50. Single dose at conc. that
  kills 50 test animals

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MSDS (cont.)

• Flashpoint - lowest T liquid vapor pressure can
  form ignitable mixture with air.
• Flammable or Explosion Limits - range of conc.
  vapor mixed with air will flash or explode if
  ignition source available

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Sections of a MSDS

• Material Identification - Description of material
  (gas, liquid, solid)
• Composition/Information of Ingredients
• Chemical components and Exposure limits
• Hazards Identification
• Health Effects, Symptoms of Exposure

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Sections of a MSDS (cont.)

• First Aid Measures
• Inhalation, Eye/Skin Contact, Ingestion
• Fire Fighting Measures
• Accidental Release Measures
• Spills, Evacuation Procedures
• Handling and Storage

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Sections of a MSDS (cont.)

• Exposure Control/Personal Protection
• Physical and Chemical Properties
• Stability and Reactivity
• Stability, Incompatibilities, By-Products
• Toxicological Information
• LC50 etc.
• Ecological Information

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Sections of a MSDS (cont.)

• Disposal Considerations
• Transport Information
• How to ship
• Regulatory Information
• Other Special Information

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Warning Marker
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Flammability

• 4 FP below -45F
• 3 FP between -45F and 100F
• 2 FP between 101F and 140F
• 1 FP between 141F and 300F

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Health

• 4 TLV of PEL lt 100 ppm and skin contact is
  poisonous
• 3 TLV of PEL lt 100 ppm and skin contact results
  in burning or irritation
• 2 TLV of PEL between 100-1000 ppm and skin
  contact results in burning or irritation
• 1 TLV of PEL between 1000 - 5000 ppm

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Reactivity

• 4 Explosive at room temp and pressure
• 3 Explosive when heated in a sealed container
  and/or explosive with water
• 2 Violent chemical change when heated but does
  not explode
• 1 Stable material that become unstable in
  combination with other materials or at
  temperature

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Special Hazards

• W-Water Reactive
• OXY-Oxidizer
• CRY-Cryogenic
• COR-Corrosive
• POI-Poisonous