Point of Use Gas Generators

Arsine Generator System

The arsine generator system provides a safe alternative to compressed gas cylinders without sacrificing arsine purity. The arsine generator uses an electrochemical process to generate high purity, low pressure arsine at the point of use. Because the gas is produced as needed, the hazards associated with the delivery, storage and handling of compressed arsine cylinders are eliminated.

A Safe Alternative to Compressed Gas Cylinders

Eliminates cylinder hazards & costly remote cylinder sheds
Low pressure, high purity AsH3 improves yield, lowers cost of ownership
5 lb. Arsine delivery capacity standard, larger sizes available
Environmentally-sound source-recycling eliminates disposal headaches
Fully Automated system delivers gas on demand
Low cost/gram AsH3 saves money over other sources

For more information contact:
Electron Transfer Technologies
155 Campus Drive
P.O. Box 5812
Edison, NJ 08818-5812

Phone: (732) 225-3995, Fax: (732) 225-3580
Email: wmaett@aol.com
Copyright ©: 1998

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Arsine Generator System

The system generates high concentrations of Arsine (AsH3) in hydrogen. Hence, hydride process deposition conditions need not be changed as with organometallic substitutes. There is also no concern about carbon incorporation into device materials.
The arsine generator system consists of an electrochemical arsine generation canister coupled to an electro-polished stainless steel manifold with computer controlled, air actuated valves and gas drier. The manifold terminates in a pressure regulator for easy connection to a mass flow controller. When active, gas pressure in the canister ranges from 5 to 30 psig. Compare that to the 500 psig found in a gas generator. In a worst case accident scenario, the ETT system might emit 1 liter of arsine, a 5 pound gas cylinder would emit 650 liters.
The system valves for evacuation, purging and operation are all automatically controlled. The control system also may be attached to an arsine monitor for automatic shut-off. The fully automated, computer controlled unit is installed in a standard, two cylinder wide, gas cabinet.
An important feature of the generator is the exchange program for the arsine source canister. When the source is depleted, the system signals the need for a new canister. The depleted canister is returned to us for recycling. We replenish the canister source material and return it to you. This eliminates your company's involvement in hazardous waste disposal. The canister is safe to ship by air freight because neither the fresh or used canisters contain gaseous arsine.
The arsine purity produced by the generator exceeds the requirements of SEMI Specification C3STD 2-81 and tests cleaner than that available from compressed gas cylinders. The generator provides up to 90% arsine in hydrogen at up to 1 liter/min. Higher flow rates are also available.

Point of use canisters vs. High pressure gas cylinders

5 Differences:

Elimination of storage: Gas is generated on demand, at the point of use, at low, safe pressures. When demand ceases, the short lines from the generator to the point of use are purged automatically. In this inactive state, the solid arsenic cathode inside the canister presents little threat to people or the environment.

Internal location: Because of the potential for a lethal accident if exposed to as little as 6 ppm of arsine, high pressure cylinders are usually housed outside the fab area, in expensive bunkers. Monitoring and real estate costs are high, and additional risk is incurred because the number of points of potential contact are increased and spread over a large area. Accidents can occur at the bunker, along the piping in the ground, entry into the building, into the fab and into the system manifold. Generating the gas only on demand in a gas cabinet next to the point of use minimizes the number of people, especially the number of untrained people coming in contact with possible points of exposure.

Reduced accident risk: The risk of a 'worst case' accident for gas generation systems is inherently much smaller than it when toxic gases are supplied by gas cylinders. The only toxic gas present in the arsine point-of-use system is that which is actually being generated and sent to the CVD reactor. With our system, we estimate that about one liter of arsine world be released by a worst-case episode. However, in a worst-case cylinder accident, up to 650 liters of toxic arsine is released from the normal 5 lb. cylinder. When the reactor stops calling for arsine, accidental risk is eliminated as automatic purge of the feed lines removes any remaining toxic gas; in contrast, the pressurized gas cylinder presents a constant risk until it is empty and purged.

Improved change out system: Change out of the arsine generator source canister is simpler and safer than with a gas cylinder. Though rare, most gas release incidents occur when lines or connections are opened. For instance, at a shift change, personnel may lose track of which parts of a system have been purged and open a connection with toxic gas present. With the ETT system, change-out of the expended canister is quick, easy and safe. No toxic gas is present in either the new or depleted canister.

Lower cost of ownership Cost of ownership of toxic gas systems includes 3 components:

the cost of the gas or source materials;
the cost of handling and storing the gas cylinders, including ventilation, scrubbers, safety training and maintenance;
the cost of recovering from a potential accident.

The cost of arsine per liter in the point-of-use system is comparable to that of gas cylinders. The capital cost of the generator and its gas cabinet is a fraction of the plant investment in toxic gas bunkers, cylinder storage areas and 100s of meters of expensive piping. The training costs are confined to fab personnel. Storage costs are minimal as canisters, depleted or full, represent no safety threat and are compact. Operating costs in terms of electricity and purge gas consumption are also minimal.
Factoring in the cost of an accident is almost impossible; it can't be predicted and the potential cost of a lethal accident is unknown. It is clear, however, that the safest systems are a fab managers' best choice. The ETT systems minimize the number of people exposed to toxic gases, confines potential leaks to a small space, one that is easily monitored, ventilated and controlled. For new fabs or when arsinide deposition systems have to be moved from installed piping, the ETT system is the safest source of high purity arsine a manager can choose!
Reference: Adams, Tom, "Point-of-use arsine generation may foreshadow future methods", Solid State Technology, June, 1995

Arsine Gas Generator (67 KB JPEG file)
500 sccm maximum flowrate arsine generator (100% arsine basis). The generator produces the purest arsine available from any source (>99.9999%) with less than 2 ppb other hydrides. Fully automated operation.
New High Output Arsine Generator (88 KB JPEG file)

Our new 1.5 liter/min (90 liters/hour) Arsine Gas Generator for MOCVD applications has three times the gas production rate of our previous model. It is capable of meeting the gas demands of the largest MOCVD reactors on the market. The Arsine Gas Generator produces the highest purity arsine available from any source (>99.9999%). The on-site gas generator eliminates the hazards of transporting, handling, and storing compressed gas cylinders of arsine. This frees companies from liabilities of possible accidents with compressed gas cylinders. Increasingly stringent EPA, OSHA, and local regulations make on-site arsine generation the most environmentally acceptable method of providing the gas.

The 1.5 liter/min Arsine Gas Generator can deliver up to 25 lbs of arsine before changing its sold source canisters. Like all our generators, the solid source canisters can be shipped by air anywhere in the world.

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