HORIBA has developed a Phosphorus Oxychloride (POCl3) delivery systems that is being implemented for atmospheric and low pressure diffusion furnaces in Europe and Asia. The system comprises HORIBA’s advanced bubblers mounted in the diffusion furnace linked to HORIBA’s automatic bulk refill system. More than 120 production furnace tubes are running with the HORIBA system with a further 100 tubes installed before the end of 2015, according to the company.

Problem

POCl3 is delivered in 1 litre quartz vessels that typically require more than 200 exchanges in a 200MW line each year. Most quartz bubbler exchanges are performed at height where there is always a risk to the health of the technician, operators and to the process itself. In addition to these risks there is also 2 hours downtime to consider for each exchange. Poor process results and additional downtime maybe incurred if the exchange is not performed well. Each quartz bubbler vessel typically can be used down to 10% of POCl3 remaining before the process becomes less stable. This ‘waste’ POCl3 cannot be used and needs to be disposed of.

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Solution

POCl3 is delivered in 20 litre canisters reducing exchanges from 200 to just 10 tank exchanges per year. Tank exchange is much safer as the canister is constructed from ETFE lined stainless steel and the exchanges are performed at ground level. Furnace downtime is eliminated as production continues even when the bulk POCl3 tank is being exchanged. When combined to the HORIBA Advanced Bubbler, the fragile quartz bubbler vessel is replaced by a fixed robust PFA bubbler vessel where the POCl3 level is maintained to guarantee full saturation and deliver stable and repeatable sheet resistance. Financial and environmental benefits are also delivered as POCl3 waste is reduced from 10% to less than 2%. An independent report from one of the largest cell producers in the world is available on request.

Applications

Atmospheric and low pressure diffusion furnaces for the delivery of POCl3 or BBr3 to produce n-type and p-type solar cells and semiconductor devices.

Platform

HORIBA has designed a robust refill system featuring fully automatic purge and safety check with integrated gas and liquid leak detection and full containment. The refill system is connected via dual containment tubing to up to 20 HORIBA advanced bubblers. The fixed bubblers are fully integrated and interlocked with the furnace.