Application of flash-assist rapid thermal processing subsequent to low-temperature furnace anneals

The substantial reductions in anneal times, such as in flash-assist rapid thermal processing !fRTP", place considerably more emphasis on the initial condition of the wafer, which may assume a greater role in the dictating diffusion product !Dt". Investigations have been conducted on the effect of low-temperature preanneals prior to fRTP on the extended defect nucleation and evolution and on boron activation. Czochralski grown n-type silicon wafers are preamorphized with 8 Ge+ ions at a constant dose of 1!1015 cm−2 and then implanted with 1 keV, 1!1015 cm−2 B. Low-temperature furnace anneals are performed at 500 °C for 30 min and the wafers subsequently subjected to flash-assist RTP anneals in the range 1000–1300 °C. Four-point probe measurements indicate that the low-temperature anneal results in higher sheet resistance values. Plan-view transmission electron microscopy, secondary-ion-mass spectrometry, and Hall-effect measurements revealed no substantial differences in defect structure, junction depth, or mobility. However, the carrier density was found to be higher for those wafers which were preannealed. © 2006 American Vacuum Society. #DOI: 10.1116/1.2140003$