Hazardous Chemicals

 

Hazardous chemicals or materials (HAZMAT) are routinely used in various aspects of the semiconductor industry. It is imperative for every employee who handles these dangerous materials to observe safety measures at all times. 

       

Being able to stay safe from these chemicals can only be achieved if the employee is aware of the following: 1) what hazardous chemicals are in his working environment; 2) the characteristics of these chemicals; 3) how these chemicals should be handled; and 4) how injury from them should be treated.  Some of the more commonly used hazardous chemicals in the industry are presented in the following tables.

                

Table 1. Corrosive Materials - Acids and Bases      

Corrosive Materials: Acids and Bases (Caustics)

Characteristics

- generally non-flammable

- can burn tissues

Protection Required

- total cover for skin and eyes where exposure is possible using the appropriate acid-/base-protective gear

Hazardous Effects

- severe burns to skin and eyes

- severe burns to the lungs if the fumes are inhaled

First Aid Treatment

- continuously flush with large amounts of running water

Examples

 

1) Hydrochloric Acid (HCl) - used in various etches

2) Sulfuric Acid (H2SO4) - used in stripping plastic and organic materials such as plastic package decapsulation

3)  Nitric Acid (HNO3) - used in various etches and, at a higher concentration, for plastic package decapsulation

4) Aqua Regia (3HCl:1HNO3) - rapid etch for Au, Pt, PtSi; highly corrosive

5) Hydroflouric Acid (HF) - highly dangerous with its ability to cause severe burns with no sensation of pain for 4 to 12 hours; used in etching silicon dioxide

6) Phosphoric Acid (H2PO4) - used in removing aluminum and silicon nitride

7)  Sodium hydroxide (NaOH) - a strong base usually in the form of hydroscopic pellets that are dissolved in water for use in various etches

8)  Potassium hydroxide (KOH) - same as NaOH

9) Ammonium hydroxide (NH4OH) - a weak base used in various etches

      

        

Table 2. Water-Reactive Chemicals     

Water-Reactive Chemicals

Characteristics

- exhibits a reaction with water, possibly a violent one

Protection Required

- store in safe containers and racks away from water

- total cover for skin where exposure is possible using the appropriate protective gear

- availability of self-contained air supply in places where fumes may be generated

Hazardous Effects

- evolves toxic, explosive, or corrosive fumes upon contact with water

- can result in explosion if the reaction is forced to confinement

First Aid Treatment

- for exposures, continuously flush with large amounts of running water

- for inhalations, immediately evacuate person to open areas with large amounts of fresh air

Example

 

Alkali metals such as Cesium - used in semiconductor-metal interface studies

    

        

Table 3. Organic Solvents

Organic Solvents

Characteristics

- generally flammable

- most are volatile

Protection Required

- protective gear for eyes and hand where exposure is possible

Hazardous Effects

- can generate fumes that are highly toxic when heated or burned

- exposure can cause skin dehydration

- prolonged exposure can damage tissue

First Aid Treatment

- for exposures, continuously flush with large amounts of running water

- for inhalations, immediately evacuate person to open areas with large amounts of fresh air

Examples

  

1) Acetone (CH3COCH3) - used for cleaning, rinsing and drying purposes 

2) Isopropyl Alcohol ((CH3)2CHOH) - used for cleaning, rinsing, drying purposes

3)  Ethylene glycol (C2H4(OH)2) - used in place of water for etches that require selectivity

      

 

Table 4. Oxidizers

Oxidizers

Characteristics

- not flammable by themselves

- can ignite or drastically increase the flammability of combustible materials

Protection Required

- keep away from combustible materials

Hazardous Effects

- can exhibit violent reactions with combustible materials that may lead to burns and other forms of injury

First Aid Treatment

- continuously flush with large amounts of running water

Examples

 

1) Oxygen (O2) - used in plasma etching, etc.

2) Hydrogen Peroxide (H2O2) - used for cleaning and etching

3) Chromic Acid  - used for cleaning and etching

   

         

Table 5. Toxic/Corrosive Gases

Toxic / Corrosive Gases

Characteristics

- compressed gas inside cylinders

- most, but not all, exhibit a noticeable odor

Protection Required

- availability of self-contained air supply where exposure is possible

- installation of gas leak detectors

Hazardous Effects

- can be highly toxic or even fatal if inhaled

First Aid Treatment

- transport to a hospital in as short a time as possible

Examples

   

1) Arsine (AsH3) - used as a source of As as n-type dopant

2) Phosphine (PH3) - used  as a source of P as n-type dopant

3) Chlorine (Cl2) - used in etching

4) Silane (SiH4) - used in deposition processes

5) Ammonia (NH3) - used as a source of nitrogen

  

         

Table 6. Bulk Nitrogen    

Bulk Nitrogen

Characteristics

- colorless, odorless gas

- displaces air

Protection Required

- availability of self-contained air supply where exposure is possible

- installation of gas leak detectors

Hazardous Effects

- can lead to suffocation and even death in areas where the air has been displaced by bulk nitrogen

First Aid Treatment

- remove from the nitrogen-filled area and transport to a hospital in as short a time as possible

      

See Also:  Wafer Fab Chemical Reactions Semiconductor Materials

 

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