9 June 2010


RASIRC presents water vapor delivery for CIGSe and thin-film vacuum processes

At the 35th IEEE Photovoltaic Specialists Conference in Honolulu, HI, USA (20–25 June), ultrapure steam purification firm RASIRC of San Diego, CA, USA is to present data detailing how ultrapure water vapor can enhance thin-film integrity in atomic layer deposition (ALD), metal-organic chemical vapor deposition (MOCVD), and sputtering processes. 

The poster ‘Water Vapor Delivery for CIGSe and Other Thin Film Vacuum Processes’ (be presented on 24 June) highlights a method for the control and delivery of water vapor that excludes particles, micro-droplets, volatile gases, and other oppositely charged species from being transferred to the carrier gas.

ALD, MOCVD and sputtering processes are used to generate transparent conductive oxide (TCO) layers and to modify crystal structures via grain size or defect repair. Direct flow control of the water needed in such applications is difficult due to the expansion of 1 gram of water to 1244cc of gas at room temperature and atmospheric pressure. Volume flows needed in sputtering applications are often less than 0.1sccm. The presentation therefore explains a method used for the control and delivery of water vapor that can determine actual selectivity in vacuum processes and the resulting improved thin-film layer integrity.

“The ability to precisely deliver water vapor free from atmospheric contaminants is critical to film integrity,” says founder & president Jeffrey Spiegelman. “We have found methods of delivering pure water vapor which not only improve results, but that are safe, cost effective, and easy to employ.”

Also, Germany’s Fraunhofer Institute for Solar Energy Systems ISE and RASIRC will present another paper, ‘Purified Steam for Industrial Thermal Oxidation Processes’, which shows that using a water vapor atmosphere instead of oxygen minimizes the thermal budget and cost of silicon solar cell fabrication, since the growth rate increases by an order of magnitude.