Growth of Nickel Silicides on Silicon by Short Duration Incoherent Light Exposure
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gROWTH OF NICKEL SILICIDES ON SILICON BY SHORT DURATION INCOHERENT LIGHT EXPOSURE
A.NYLANDSTED LARSEN, J.CHEVALLIER, and G.S0RENSEN Institute of Physics, University of Aarhus, DK-8000 Aarhus C,
Denmark
ABSTRACT Short duration, incoherent light from a xenon lamp has been used to grow nickel silicides on silicon single crystals from evaporated nickel films. The formation of these silicides was studied by Rutherford Backscattering Spectrometry, channeling, sheet resistivity, and transmission electron micro0 scopy as function of induced temperature (550- 775 C), exposure time (8- 25 sec), and silicon orientation (, , and ). Epitaxial NiSi 2 films were formed for tempera0 tures above %675 C whereas polycrystalline NiSi films were rformed below this temperature.
INTRODUCTION The use of short duration light exposure to remove radiation damage in ion implanted semiconductors and to make the implanted impurities electrically active has been studied extensively in the last years [1-3]. The method has yielded very promising results. The quality of the recrystallized layers and the degree of electrical activity of the implanted impurities are comparable to what has been obtained by long-duration furnace annealing, however, with negligible impurity redistribution at moderate implanted doses. In addition, the method has the potential of a very high throughput and easy automation. As metal silicides become of increasing importance in the semiconductor industry as ohmic contacts and low resistance interconnections [4], it is of importance to investigate whether this new annealing method be compatible with the formation of metal silicides in the sense that 1) metal silicides can be formed by short duration, incoherent light exposure and 2) the same temperature and time regime can be used to anneal the radiation damage and to form metal silicides so that both processes can be done in one step. In the present paper, the formation of nickel silicides on silicon single crystals by short duration incoherent light exposure is reported.
EXPERIMENTAL PROCEDURE Nickel films ranging from 300 A to 425 A in thickness were deposited by e-gun evaporation in a vacuum of 10-6 Torr on polished ntype Si, , , and oriented wafers. Incoherent light annealing was carried out by means of a short-arc xenon lamp. Samples were mounted on a thermally isolating support in a small chamber sealed by a quartz plate so that all annealing could be done in an inert nitrogen atmosphere. Figure 1 illustrates variation of silicon sample temperature for a 15-sec annealing at 0 715 C showing that steady-state temperature is attained within the first 10 sec of exposure for this particular temperature. A further description of the apparatus is given in ref.3. The fltoichiometry and thicknesses of the silicides were determined from Rutherford Backscattering Spectrometry (RBS) using 2-MeV a-particles and epitaxy was studied by 2-MeV a-particle channeling. Samples for transmission electron microscopy (TEM) were prepared by etching from
Mat. Res. Soc. Symp.
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