Photo-reflectance characterization of USJ activation in millisecond annealing

摘要

Photo-reflectance (PR) provides an optical means for rapid and precise measurement of near-surface electric fields in semiconductor materials. This paper details the use of photo-reflectance to characterize dopant activation in ultra-shallow junction (USJ) structures formed using millisecond anneal processes. USJ structures were formed in silicon using 500eV boron implantation with a dose of 10~(15)/cm~2, followed by flash anneals at 1250-1350℃. Reference metrology was performed using secondary ion mass spectroscopy (SIMS) and various sheet resistance (R_s) methods. Methods to calibrate photo-reflectance signals to active carrier concentration in USJ structures, including halo-doped samples, are described. Photo-reflectance is shown to be highly sensitive to active dopant concentration in USJ structures formed by millisecond annealing. Additionally, PR provides fast "on-product" measurement capability.