C, Si and Sn Implantation of CVD Diamond as a means of Enhancing Subsequent Etch Rate
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C, Si and Sn Implantation of CVD Diamond as a means of Enhancing Subsequent Etch Rate P.W. Leech1, T. Perova2, R.A. Moore2, G.K. Reeves3, A.S. Holland3 and M. Ridgway4, 1 CSIRO Manufacturing and Infrastructure Technology, Clayton, Victoria, Australia. 2 Dept. of Electronic and Electrical Engineering, University of Dublin, Trinity College, Ireland. 3 RMIT University, School of Computer Systems and Elect. Eng., Melbourne, Australia. 4 Dept. of Electronic Materials Engineering, ANU, Canberra, Australia.
ABSTRACT Diamond films were implanted with C+, Si+ or Sn+ ions at multiple energies in order to generate a uniform region of implantation-induced disorder. Analysis of the C+ implanted surfaces by micro-Raman spectroscopy has shown only minor increase in the proportion of nondiamond or sp2-bonded carbon at doses of 5 x 1013 - 5 x 1015 ions/cm2. In comparison, an amorphization of the structure was evident after implantation with either Si+ ions at a dose of 5 x 1015 ions/cm2 or with Sn+ ions at >5 x 1014 ions/cm2. At a given implantation dose, the etch rate of the diamond film in a CF4/O2 plasma increased with the mass of the implanted species in the order of C+, Si+ and Sn+. For a given implant species, the etch rate was directly proportional to vacancy concentration as controlled by the dose or the implantation-induced disorder.
INTRODUCTION Diamond films manufactured by chemical vapour deposition (CVD) have shown important potential in applications such as inert biosensors and ultra-low friction electromechanical devices. A critical step in the realisation of many of these devices has been the development of techniques for the patterning and selective etching of the diamond films. Several techniques have been successfully reported in the etching of diamond as reviewed in ref. [1]. One of the most widely applied of these techniques has been reactive ion etching (RIE) in an oxygen plasma. But while oxygen RIE has allowed the definition of fine structures in diamond, the etching has been characterised by surface roughening. The alternative use of SF6 [2] or CF4 [3] gases has produced a significantly smoother surface than with oxygen plasmas, although also with the limitation of a low etch rate. In this paper, we have examined for the first time the use of implant-induced damage as a means of increasing the rate of subsequent reactive ion etching of diamond in CF4/O2 plasmas. The etch rate of the films has been examined as a function of the ion dose and the mass of the implant species (C+, Si+ or Sn+). Previous work has identified a correlation between implant dose and the extent of damage in both CVD films [4,5] and single crystal diamond [5]. Ion implantation at low doses resulted in the formation of clusters of point defects around each track [4,5]. At intermediate doses, the implantation produced a partial graphitisation while a full amorphisation was evident above a critical level of dose, Dc, dependent on the implanted ion [46]. In this work, the etch rate of the diamond has also been measured versus the r
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