Femtosecond laser induced forward transfer of indium thin films JOHN THOMAS, 1 RODNEY BERNARD, 1 JOHN T. THOMAS, 1 KAMLESH ALTI, 1 SANTHOSH CHIDANGIL, 1 SATCHI KUMARI, 2 ALIKA KHARE, 2 AND DEEPAK MATHUR 3 1 Centre for Atomic and Molecular Physics, Manipal University, Manipal, India 2 Department of Physics, Indian Institute of Technology Guwahati, Guwahati, India 3 Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai, India (RECEIVED 12 July 2013; ACCEPTED 17 September 2013) Abstract We report utilization of the laser induced forward transfer technique to re-deposit indium thin films onto the accepter substrate using nJ laser pulses from a femtosecond laser oscillator. Keeping the accepter substrate stationary enables dots of Indium to be deposited; in contrast, linear motion of the accepter substrate facilitates deposition of lines of Indium. The effect of laser pulse energy on the deposition process is studied. The effect of translation speed of donor substrate on the laser induced forward transfer pattern is also probed and an upper limit of translation speed is established beyond which smearing is observed to occur. Keywords: Indium thin films; Laser induced forward transfer 1. INTRODUCTION Nanosecond and femtosecond lasers have been extensively used in recent years for machining and laser-writing of thin films of different kinds. The use of lasers is now beginning to also find utility in controlled, micron-sized deposition of materials on to substrates, with applications spanning diverse fields like micro-electronics, opto-electronics, semiconductor industries, and biomedical research. Laser-induced forward transfer (LIFT) is one such micro-deposition technique that has recently evolved; it facilitates transfer of particles from thin films to other proximate surfaces by focusing nanose- cond or femtosecond laser pulses from the rear side of a thin film that is deposited onto a transparent substrate (see Fig. 1 for a schematic depiction of a typical experimental configuration). LIFT was first reported by Bohandy et al. (1986) for patterned copper deposition. Depending on the laser-thin film interaction, micron- or nano-sized material are ejected from the irradiated thin film and are deposited onto another substrate that is located sufficiently close to it. LIFT technique has been applied on variety of materials. For example, it have been used for transferring radioactive contaminants (Veiko et al., 2006), laser dyes (Nakata et al., 2002), superconducting materials (Fogarassy et al., 1989), DNA (Colina et al., 2005), microarrays of DNA (Seera et al., 2004), Trichoderma longibrachiatum conidia (Hopp et al., 2005), thermally and mechanically sensitive materials (Kattamis et al., 2007) and thin films of various metals for example gold (Nakata & Okada, 1999) indium (Alti, 2008) aluminum using femtosecond (fs) laser (Bera et al., 2007), and aluminum zinc and chromium using tem- porally shaped fs pulses (Klini et al., 2008). LIFT offers some unique advantages over other tech- niques. First, there is no chemical reaction involved in the LIFT process: the technique is, as a consequence, a “green” technique in that it permits retention of the purity of deposited microelectronic materials. Second, LIFT can be implemented under ambient atmospheric conditions. As already noted, LIFT has been demonstrated using both 55 Fig. 1. Schematic diagram of the LIFT (laser induced forward transfer) technique. Address correspondence and reprint requests to: Kamlesh Alti, Depart- ment of Physics, Sant Gadge Baba Amravati University, Amravati- 444602, India. E-mail: kamleshalti@sgbau.ac.in Laser and Particle Beams (2014), 32, 55–61. © Cambridge University Press, 2013 0263-0346/13 $20.00 doi:10.1017/S0263034613000827