Electron-Beam Plasma for Silicon Technologies
Electron-Beam Plasma for Silicon Technologies
Tech Area / Field
- MAT-SYN/Materials Synthesis and Processing/Materials
8 Project completed
Senior Project Manager
Mitina L M
Keldysh Research Center, Russia, Moscow
- Institute of Thermophysics, Russia, Novosibirsk reg., Novosibirsk
- Technishe Universiteit Eindhoven / Department of Physics, The Netherlands, Eindhoven\nIMEC, Belgium, Leuven
Project summaryThe purpose of this project is development (on the basis of previous studies of the authors and project-planned researches) of technical assignment for pilot installations for realization of the following technologies, based on electron-beam plasma investigations:
– deposition of hydrogenated amorphous silicon films for production of thin-film solar cells with gases activated by electron-beam plasma, created in a supersonic jet;
– deposition of polycrystalline silicon layers and creation of testing photovoltaic elements by the jet method with gases, activated in electron-beam plasma;
– conversion of tetrachloride silicon (SiCl4) into trichlorosilane (SiHCl3) with activation of the chemical reaction in the flow-through reactors with electron-beam plasma.
The actuality of these applications of electron-beam plasma technique is determined by the following reasons:
1. Now the thin-film solar cells of amorphous silicon are considered as the best opportunity for a large-scale production of SC (Photovoltaic Insider's Report vol. XVI № 11, Nov.1997). The main restricting factor for market opportunities for SC is its high production cost, in generally determined by the low lines speed for SC production. Now the glowing discharge technique is the dominant method on these lines. The deposition rates of amorphous silicon films, achieved by this method is low yet – about (2÷3) A/s. This circumstance leads to the SC price increasing. New technique, offered in given work, provides the abrupt (in several tens times) increasing of film deposition rates on the high-area uniform with good quality of films. The new method can be a good alternative for the glowing discharge technique.
2. Solar cells on polycrystalline silicon are also one of the possible candidates for large-scale production of SC. The combination of SC on amorphous and polycrystalline silicon is also possible. Laboratory testing of these samples demonstrates a higher and stable efficiency, than SC from amorphous silicon. For that kind of solar cells, the photo-active layers of polycrystalline silicon must be of (20÷30) m thickness, that is, by 50÷100 times thicker than in SC from amorphous silicon. That is, the problem of method creation for production of high quality silicon layers of this thickness is even more crucial, than for SC with a-Si:H. There are also some specific problems, determined by the necessity of poly-Si layer depositing at the more less temperatures, than the temperatures of poly-Si achievement by the thermal heating method. A high-scale production of SC from a-Si:H would require reduction of energy consumption for this process (this problem will be more severe for poly-Si product). New method, offered in given work, provides the local deposition rates for silicon films above 0.1 µm/s. In general, these rates may be more increased. The specific energy consumptions, achieved by this method, are by (50÷100) times lesser, than during thermal plasma usage. Besides, the jet transportation of plasma-excited particles provides nonequilibrium heating of the top (growing) layers of the film. This can reduce the temperature of the substrate at which the poly-Si layers deposit.
3. The chlorine technology for production of polycrystalline silicon yields one ton of semiconductor silicon per 15 tons of tetrachloride silicon as a waste. This product must be recycled. The laboratory experiments of project authors proved that using of electron-beam plasma is a very promising method for conversion of SiCl4 into SiHCl3 plus HCl is a flow-type low-temperature compact reactors with a low energy consumption (0.5 kW×7hour per kg).
In these two applications the electron-beam plasma is the main element of the technique. The purposes of this project are experimental data and theoretical calculations, on which base the laboratory setups of the devices will be designed and tested. Basing on these investigations the technical assignments for fabrication of pilot half-industry devices will be designed.
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