Enhancement in Adhesion of Pt Films on Ceramics by Helium Ion and Electron Irradiation, and a Study of their Electrochem
- PDF / 2,314,684 Bytes
- 6 Pages / 417.6 x 639 pts Page_size
- 38 Downloads / 170 Views
ENHANCEMENT IN ADHESION OF Pt FILMS ON CERAMICS BY HELIUM ION AND ELECTRON IRRADIATION, AND A STUDY OF THEIR ELECTROCHEMICAL BEHAVIOUR.
D.K. SOOD*, P.D. BOND* AND S.P.S. BADWAL**. *Microelectronics Technology Centre, Royal Melbourne Institute of Technology, Melbourne 3000 Australia. **CSIRO Division of Materials Science, Advanced Materials Laboratory, P.O. Box 4331, Melbourne 3001 (Australia)
ABSTRACT The adhesion of Pt films (10-330nm thick) sputter deposited on prepared substrates of yttria stabilized zirconia (YSZ) and alumina has been observed to be remarkably enhanced after irradiation with 2 MeV He++ ions and 5-30 keV electrons. The adhesion enhancement has been studied as a function ot beam energy, dose and film thickness. Thermal stability of adhesion enhancement and of the microstructure of 'stitched' films has been investigated. The electrochemical behaviour of 'stitched' Pt electrodes on YSZ has been studied by complex impedance spectroscopy.
INTRODUCTION Bombardment of thin films with low energy (up to a few hundred key) heavy ions has been known [1,23 to lead to dramatic improvements in their adhesion to the substrate surface. The ion beam energies employed in such experiments have been in the nuclear stopping region and the adhesion enhancement can be attributed to atomic mixing effects at the interface. Similar enhancements in adhesion of metallic films on metal, semiconductor and insulator substrates were recently obtained[3-5] on bombardment with MeV/amu heavy ion beams in the electronic stopping region. It has been suggested[4jthat the mechanism for this enhanced adhesion ('stitching') effect involves electronic energy loss at the film-substrate interface with no mass transport or atomic mixing effects. A direct proof of purely electronic origin of this effect has been provided by enhancement in adhesion of thin Au films on Si produced by bombardment with electrons of 5 - 30 keV energies which are well below the atomic displacement thresholds[6]. This paper presents a comparative study on adhesion enhancement of Pt films on ceramics by helium ion (in the electronic stopping region) and electron bombardment. Yttria stabilized zirconia and alumina have been chosen as substrate materials for this study. YSZ is an important electrolyte for several solid state electrochemical devices such as oxygen sensors, fuel cells and steam electrolysers. Alumina is widely used in electronic and refractory industries. It is highly desirable, though often a difficult task, to produce robust and adherent metallic contacts on these ceramics. Ion/electron beam induced adhesion may be a promising technique. The thermal stability and electro-chemical behaviour of 'stitched' Pt electrodes on YSZ have therefore been studied.
EXPERIMENTAL Stabilized zirconia discs (9 mm diam, 1.5 mm thick, nominal density -93%) of 7 mol % Y2 0 3 + 93 mol % Zr 02 were prepared, polished to mirror finish and cleaned as described in ref.7. Alumina samples (19 mm square) Mat. Res. Soc. Syrup. Proc. Vol. 27 (1984) Qzlmevier Science Publishin
Data Loading...
