Effect of Laser Heating on Compositions of Films Deposited from the Metal Hexacarbonyls
- PDF / 1,349,600 Bytes
- 6 Pages / 420.48 x 639 pts Page_size
- 81 Downloads / 175 Views
EFFECT OF IASER HEATI ON C4PSrITIONS OF FILMS DEPOSITED FRCK THE METAL HEXACARBONYLS K. A. SINGMSER San Jose State University, Dept. of Chemistry, San Jose, CA F. A. HOULE IBM Research Division, Almaden Research Center, CA 95120
95192-0101
650 Harry Road, San Jose,
ABSTRACT A systematic study of the composition of metal films thermally deposited by laser heating (cw 514 rum) of the group VI hexacarbonyls is described. The films are found to contain significantly lower levels of carbon and oxygen than photochemically deposited films, and are spatially inhcmogeneous. Estimates of temperature to determine the extent of laser heating permit the kinetics of this process to be compared to C) desorption from single crystal surfaces. INTRODUJCTION The effects of both cw and pulsed UV photolysis on the composition of metal films deposited fran M(COD) 6 , where M = Cr, Mo or W, have been well documented [1]. Under cw photolysis coiditions, where laser heating is minimal, the films exhibit significant levels of carbon and oxygen contamination that are attributed to the dissociative chemisorption of 00, consistent with what is known about CO chemistry on group VI metal surfaces. Surface studies also indicate that higher temperatures (T > 800 C) result in the removal of C and 0 atcms from the surface, leaving the metal surface clean, suggesting that thermal deposition coupled with photochemistry could produce clean metallic films. This has not been the case [2], the complex photochemistry occurring with high peak laser powers may play a role in the incorporation of impurities. This leaves open the question as to whether thermal decomposition in the absence of photochemistry will produce cleaner metal films. Although several research groups have demonstrated that tungsten films and lines can be deposited by exposure of the hexacarbonyl vapor to 514 nm light only two have provided compositional information [3]; clean metal films were observed deposited on 2/A thick Si membranes [4], while on quartz substrates only 75 % metallic deposits were obtained [5]. Less is known about Cr(00)6 and Mo(CO)6 although it has been demonstrated that films of unknown composition can be deposited fron these materials by cw 488 run light [6]. The goals of the
work outlined in this paper are to systematically investigate the elemental
compositions of metal films deposited by laser heating of the group VI hexacarbonyls and to learn as much as possible about the correlation of the observed results to surface studies of 00 and hexacarbonyls. ERIMEAL SECTION All films were deposited on Si(100), doped p-type (10 ohms-cm), cleaned in an acid oxidant bath and left covered by its native oxide. The light source was an Ar ion laser focused to a 10 micron spot. Films were grown during exposures rangV fran 200 ms to 120 s using incident power densities from 1.5 - 4.0 MW/c. The first film deposited on the substrate 2 was always at 4 MW/cm power density and long exposure time (k 30 s). Additional films were grown at separations of imn. This first film Mat. Re
Data Loading...
