Laser Forward Transfer of Electronic and Power Generating Materials

1. INTRODUCTION The application of laser forward transfer techniques has steadily grown since the first reports of patterned copper deposition by Bohandy, et al. 20 years ago (Bohandy, 1986). These general techniques employ a pulsed laser to locally transfer material from a source film onto a substrate in close proximity or in contact with the film. The source is typically a coated laser-transparent substrate, referred to as the target, donor, or ribbon. Laser pulses propagate through the transparent ribbon until they are absorbed by the film. Above an incident laser energy threshold, material is ejected from the film and transferred toward the acceptor, waiting or receiving substrate. These laser forward transfer techniques, known as laser direct-write (LDW), belong to a class of processes capable of generating a high-resolution pattern without the need for lithogaphic processes afterwards. Other examples of laser direct-write techniques include pyrolitic or photolytic decomposition of gas-or liquid-phase precursors, also known as laser CVD or laser-assisted deposition (Osgood, 1985; Herman, 1989). However, these non-forward transfer techniques will not be discussed in this chapter because they are not ablative in nature. Translation of the ribbon and receiving substrate, and/or scanning and modulating the laser beam enables complex pattern formation. Commercially available, computer-controlled translation stages or galvonometric scanning mirrors enable high-resolution patterns from the individually written 3D pixels or voxels resulting from the laser forward