Updated: July 2002

1. PFC gases

Semiconductor manufacturing requires large quantities of a wide variety of gases in all processes from prototyping to mass-production. Many of these gases are toxic, corrosive, flammable or flame-supporting and require extensive safety measures and the utmost caution during handling. On the other hand, restrictions on the types of gases permitted to be used are becoming tighter for reasons of global environmental protection.

Information on PFC gases

The World Semiconductor Conference held in April 1999 adopted the goal for 2010 of a 10% reduction compared with use in 1995 for PFCs, HFCs, SF6 and NF3.
The treatment and processing technology for these gases is increasing in importance, creating in turn a demand for higher levels of processing safety, lower cost, more compact equipment, and treatment technology for newly adopted gases.

2. Current status of treatment equipment

Equipment can be classified into the following two groups according to treatment principle.
1) Chemical method
Conversion to non-toxic products by a chemical reaction of a toxic gas with a vapor-phase, liquid-phase, or solid-phase reaction material.
2) Physical method
Collecting toxic material by physical attachment to a solid-phase absorbent.

Equipment can also be classified into dry type and wet type according to the operating method.
1) Dry type
(1) Combustion type
(2) Thermal decomposition type (including auxiliary wet types)
(3) Chemical reaction type
2) Wet type (Reaction and dissolution by vapor-liquid contact using water or chemicals)
Shown below are the advantages and disadvantages of the major treatment methods.

3. Treatment system proposed by MEA

The PFC/SF6 removal equipment described below does not require water treatment equipment since it utilizes a thermo-chemical reaction method operated at a lower temperature than that of the combustion method combined with energy-saving measures such as exhaust heat collection.
The easy-to-handle treatment column unit replacement method reduces the operator's onsite workload.
The primary feature of this equipment is the collection of toxic ingredients removed by the reactant in the form of CaF2, which can be recycled as a raw material for cement. (Zero waste)

System flow (reference)

System description
1) Use
Removal of PFCs and SF6
2) Decomposition reactant
Calcium-based reactant (reaction chamber capacity 100 liters)
3) Utility
Power:
200 V, 21 kVA (for equipment power), approximately 2 kVA during constant operation
100 V, 1 kVA (for control power)
Air:
0.4-0.7 MPa (for operating automatic valves)
0.01-0.1 MPa (for promotion of reaction)
Cooling water: 4 liters/min (for cooling cabinet)
Exhaust: -0.1 - 1kPa (for treated gas, cabinet)
4) Decomposition method
PFCs + Calcium reactant -> CaF2 + CO2
SF6 + Calcium reactant -> CaF2 + CaSO4
5) Processing capacity

* The above values are estimated from experiments using a single gas and are not guaranteed values.

6) Equipment dimensions
Processing box 1750W×850l×1650H
Control panel 500W×850l×1650H