UNIFORM BETA-SIC THIN-FILM GROWTH ON SI BY LOW-PRESSURE RAPID THERMAL CHEMICAL VAPOR-DEPOSITION

Beta-SiC thin films have been grown on Si by rapid thermal chemical deposition at reduced pressures (LP-RTCVD) as low as 5 Torr. The growth process involved the carbonization of the (100)Si surface by reaction with propane. Reducing the pressure resulted in a monotonic increase in growth rate. At a reaction temperature of 1300-degrees-C, using 100 sccm of C3H8 (diluted to 5% in H-2) and 0.9 1pm H-2 carrier gas yielded a growth rate of 0.45 angstrom/s at 760 Torr and 18 angstrom/s at 5 Torr. A substantial increase in film thickness uniformity was observed at low pressure. At 5 Torr, the average thickness and standard deviation measured over the area of a 7.5 cm diam wafer were 1602 and 46 angstrom, respectively. This low standard deviation for LP-RTCVD, equivalent to 2.87% of the average thickness, is the result of uniform growth over the entire specimen, including the edge region. In contrast, atmospheric pressure RTCVD results in severely nonuniform growth in the vicinity of the wafer edge.