Range parameters of B n cluster ion implantation in silicon

Abstract

In this study, boron depth profiles of as-implanted and as-annealed B n cluster ion implantation in silicon were investigated in terms of their range parameters. The B n cluster ion implantations were performed at the same cluster energy of 77 keV, corresponding to an equivalent boron energy of 77/ n keV for various B n cluster ions. The implantation cluster ion fluence employed for various B n cluster ions was 5 × 10 13/ n cm −2 in order to obtain a constant atomic boron fluence of 5 × 10 13 cm −2. Post-annealing treatments were conducted using rapid thermal annealing at 1050 °C for 25 s. Secondary ion mass spectrometry (SIMS) was used to measure boron depth profiles, which were then least-squares-fitted to a Pearson distribution in order to assess range parameters of projected range, longitudinal range straggling, skewness, kurtosis and transversal range straggling. The results revealed that projected range, longitudinal range straggling and transversal range straggling decrease but skewness and kurtosis increase as cluster size increases. In addition, radiation-enhanced diffusion (RED) induced by implantation damage and rapid thermal annealing increases all five range parameters. Resistivity measurements using a four-point probe indicated that sheet resistance of the as-annealed specimens increases as cluster size increases because a larger cluster size leads to greater implantation damage in the near-surface region.