Application of Excimer Laser Processing in SiC Device Fabrication
Activation of dopants implanted into SiC is a key processing step in SiC device fabrication. Until now, activation of n-type dopants in SiC required temperatures higher than 1300°C, with higher temperatures required for p-type dopants. At these high temperatures, most common dielectrics used in processing will be molten and the properties of many metals or metal silicides change. This poses severe difficulties for SiC device fabrication. Excimer processing utilizes a well-controlled XeCl laser beam pulse or pulses (308 nm and 3.9 eV) of a duration of about 30 ns. The process is a local and nonequilibrium process. Using a suitable masking material, a selected area on a SiC substrate can be heated to a high temperature (even to melting temperature) within a few nanoseconds. Since the heating time is so short, the heating is limited to the region within a few tenths of a micrometer (depending on the laser beam energy and pulse duration) of the surface in the unmasked area, with little propagation vertically or laterally. The talk will present the results of laser annealing, melting and recrystallization of β- and 6Hβ-SiC doped with Ga or Al. A Rutherford Back Scattering (RBS) analysis of the ion-implanted and laser-processed SiC layer will be discussed.