SIMS and modeling of ion implants into photoresist

Silicon wafers were coated with Shipley AZ-7500 photoresist and SIMS was carried out directly on the resist and the underlying silicon. The samples were implanted with B, P, and As with a dose of 5E13/cm² in the 100 to 1500 keV energy range. Two different resist thicknesses were picked: a 3 μm resist to completely stop the ions within the resist and a 2.3 μm resist to allow partial penetration of the implant into the silicon substrate. SIMS was done with 5.5 keV O₂⁺ or 3 keV Cs⁺ on carbon-capped specimens. The SIMS data show a sharp transition at the photoresist to silicon interface indicating high depth resolution. Comparison of single versus multiple implants demonstrate that the implants do not interfere with each other. Range, sigma, and skewness are extracted by matching the SIMS profiles within SUPREM-3. With the exception of an exponential tail in the front-side of the implant maximum for the boron profiles, agreement between SIMS and simulation is good. Results were compared with the predictions of TRIM using the gravimetrically-measured density and known chemical composition of the cured resist. TRIM data were fitted by adjusting the density and adding a range offset, resulting in an excellent agreement over the entire energy range. From these fitted data, graphs for range and sigma from 0-2 MeV were derived. Analytical expressions for skewness and kurtosis are presented