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Chemical and physical processes during the formation of MoSi2 by ion-beam mixing

: Möller, W.; Ryssel, H.; Valyi, G.

Nuclear instruments and methods in physics research, Section B. Beam interactions with materials and atoms 39 (1989), pp.268-271
ISSN: 0168-583X
International Conference on Ion Beam Modification of Materials <6, 1988, Tokyo>
Journal Article, Conference Paper
Fraunhofer IIS B ( IISB) ()
Halbleitertechnologie; Ionenstrahlmischung; Molybdän-Silicid

The formation mechanism of MoSi2 layers fabricated by implanting arsenic ions through 40-70nm of molybdenum into silicon was studied. The implantation parameters were varied (dose 5x10 high 14 to 3 x 10 high 16 cm high minus 2, current density 1,1 to 22,6 myAcm high minus 2) and their influence on the formation of the silicide was studied. While below 360 degrees C, the thickness of the intermixed molybdenum layer is proportional to the square root of the implanted dose, at higher temperatures, it is proportional to the dose itself. This can be explained by different mechanisms in the different temperature regions. Whereas at low temperatures, physical effects dominate (ballistic mixing), at higher temperatures, molybdenum and silicon react chemically. In the low temperature region, the mixing can be simulated using a dynamic Monte Carlo code (TRIDYN). At high temperatures the silicidation reaction has an activation energy of 0,3 eV which is much lower than the activation energy of a t hermal activated process. This behavior can be explained by the effect of thermal spikes which enhance the temperature by about 1600-1700K. Rapid annealing in N2 ambient after implantation resulted in a specific resistivity of 80 myohmcm.