Product category:
OEM Pumps
News Release from: Edwards | Subject: Dry vacuum pumps
Edited by the Engineeringtalk Editorial
Team on 04 October 2002
Dry vacuum pumps help cut solar cell
costs
A new continuously operating high-capacity coating technique for producing multi-crystalline-based solar cells uses dry vacuum pumping technology from BOC Edwards.
Roth and Rau, one of the leading manufacturers of production equipment for silicon nitride antireflection and passivation layers used in multi-crystalline-based solar cells, has developed a novel continuously operating high capacity coating technique A key element of the new equipment is the dry vacuum pumping technology from BOC Edwards
This article was originally published on Engineeringtalk on 21 Jun 2001 at 8.00am (UK)
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Solar energy is growing in popularity as an environmentally friendly energy source.
This new process from Roth and Rau, which helps make a significant reduction in the cost of solar cell production, is a major boost for the application of solar energy worldwide.
The plant at Wuestenbrand, Germany, manufactures the systems which are suitable for coating all sizes of solar cell and, depending on wafer size, boast a throughput of up to 1400 wafers per hour.
Further reading
High capacity for novel "dry" vacuum pump
The CDX1000 is the first of a new family of dry vacuum pumps from BOC Edwards.
Dry vacuum pumps gain lab approvals
BOC Edwards has been awarded UL3101 and CSA C22.2 1010 approvals for its highly successful XDS range of dry vacuum scroll pumps.
The wafers to be coated are transported on special carriers in batches of up to 49 through the processing system.
After passing through a load lock which is evacuated to 0.001mbar, the wafers are heated to the process temperature of 3500C.
The next step takes place in the process chamber and involves the deposition of silicon nitride from a silane/ammonia mixture using specially developed plasma sources at a working pressure of 0.08-0.5mbar.
The required film thickness is 70-80nm.
After cooling in a cooling chamber, venting with nitrogen follows and the carriers exit via the outlet lock.
The wafers can be loaded and unloaded via an optional automated system.
Oil-free pumping chambers are a distinguishing feature of these pumps: contamination of the solar cells due to backstreaming of sealing and operating oil into the process chambers therefore cannot occur.
As neither sealing nor filtration media are present in the pump, no costly waste disposal is necessary.
The pumps require very little maintenance, thus contributing to long service intervals for the production units in which they are used.
Three pump combinations consisting of an EH4200 booster pump and a GV600M dry pump are used with each unit.
One pump set is used for each of the two load locks and one for the process chamber.
By using three identical sets, spares stocking can be reduced to a minimum.
The mechanical booster pump EH4200 is equipped with a patented hydrokinetic coupling, which makes possible faster pumpdown from atmosphere compared to similar pumps based on bypass valves or pressure sensors.
The GV600M dry pump consists of a unique combination of one roots and three claw stages and thus achieves a very good end vacuum and high pumping speeds.
Purging the individual stages and the exhaust with nitrogen prevents process dust being deposited in the pump and auto-ignition of silane in the exhaust.
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