Pulsed Proton Beam Annealing of Co-Si Thin Film Systems
- PDF / 1,657,340 Bytes
- 6 Pages / 417.6 x 639 pts Page_size
- 28 Downloads / 203 Views
PULSED PROTON BEAM ANNEALING OF Co-Si THIN FILM SYSTEMS
L. J. CHEN Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan, ROC. L. S. HUNG and J. W. MAYER Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853 J. E. E. BAGLIN IBM T. J. Watson Research Center, Yorktown Heights, NY 10598
ABSTRACT Cobalt (~300A') and CoSi 2 (~1000A') thin films on Si have been annealed by intense proton beams. RBS and TEM were performed to study ion beam annealing effects. 2 For ion beam energy densities above about 1 J/cm , epitaxial CoSi 2 layers were formed for both Co and polycrystalline CoSi 2 on Si. At low energy densities, Co 2Si was found to coexist with Co. The results are discussed in terms of eutectic melting processes.
INTRODUCTION
Metal silicides have in recent years received a great deal of attention in the microelectronics industry as Schottky barriers, ohmic contacts, gate electrodes and interconnects. The silicides are generally formed by reacting a thin layer of metal film with substrate silicon at elevated temperatures [1]. Within the past few years, intense energy beams such as laser, electron and ion beams have been used to react metal/Si thin films to form silicides [2]. The techniques offer several advantages over traditional furnace annealing such as shorter reaction times, localized heat treatment and less stringent ambient control. Most of the investigations in this area have been limited to pulsed laser, CW laser and CW electron beam annealing. The principal results obtained with scanned CW electron beams are similar to those produced with scanned CW lasers. Cellular structures were found to result from pulsed laser annealing. The formation of such cellular structures is attributed to the formation of cells by segregation as the melt front moves toward the surface. CW laser or electron beams, on the other hand, produced basically uniform silicide layers similar to those induced by furnace annealing. High power pulsed ion beams have been used [3] to process nickel thin films on silicon. At high energy densities, cellular structures were observed similar to those produced in laser annealing. However, at lower energy densities, epitaxial silicide layers were formed. This represented the first report of the formation of epitaxial silicide layers by pulsed beam annealing in the melt-quench regime. At lower energy densities, polycrystalline layers containing a mixture of Ni 2Si, NiSi and NiSi 2 were formed with an average composition Mat.
Res.
Soc.
Symp. Proc.
Vol.
13 (1983) OElsevier Science Publishing Co.,
Inc.
710
within the layer near that of NiSi [4]. The structural changes induced by pulsed ion beams were explained in terms of a melting mechanism. In this paper, we report the results of pulsed proton beam annealing of Co-Si thin film systems.
EXPERIMENTAL PROCEDURES
Cobalt thin films, 3000A in thickness, were e-gun deposited on (001) and (111) oriented, 29-cm, n-type Si at room temperature. Some of the samples were anneale
Data Loading...
