US Patent 10193004 LIFT printing of conductive traces onto a semiconductor substrate

A method for metallization includes providing a transparent donor substrate (34) having deposited thereon a donor film (36) including a metal with a thickness less than 2 pm. The donor substrate is positioned in proximity to an acceptor substrate (22) including a semiconductor material with the donor film facing toward the acceptor substrate and with a gap of at least 0.1 mm between the donor film and the acceptor substrate. A train of laser pulses, having a pulse duration less than 2 ns, is directed to impinge on the donor substrate so as to cause droplets (44) of the metal to be ejected from the donor layer and land on the acceptor substrate, thereby forming a circuit trace (25) in ohmic contact with the semiconductor material.