Metal clusters in plasma polymerized fluorocarbon films: Cobalt-aluminum

Abstract

Plasma processes are described which lead to the dispersion of metal containing clusters in dielectric film matrices. In contrast to Au clusters dispersed in a polymer film matrix as reported earlier [E. Kay and M. Hecq, J. Appl. Phys. 55, 370 (1984)], this report deals with reactive metals such as A1 and Co dispersed in metal fluoride and/or fluorocarbon matrices depending on the composition of the plasma. Optical emission data of the plasma together with film deposition rate and composition measurements for films produced at different substrate temperatures indicate that the adsorption step of (CF2)„ polymerization precursors is the rate limiting process in the overall polymerization. Electrical conductivity shows 16 orders of magnitude changes in films made just above and below a critical fluorocarbon/argon gas mixture in the plasma resulting in a critical metal cluster volume fraction in the films. These film characteristics are associated with percolation phenomena. In the case of A1 evidence is given that granular A1 is obtained by these plasma processes and that associated changes in superconducting transition temperatures Tcare not exclusively related to metal cluster size [M. Hecq, P. Ziemann, and E. Kay, J. Vac. Sci. Technol 1, 364 (1983). © 1984, American Vacuum Society. All rights reserved.