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Scanning capacitance microscopy (SCM) has been widely used to examine the electrical junction profiles of silicon-based devices. In general, ion implantation combined with proper annealing treatments is indispensable to produce a needed electrical junction. The annealing treatments can be rapid thermal annealing, laser annealing or spike annealing (SA). Due to photoperturbation problems within SCM, there are many difficulties in employing typical SCM to study the subtle correlations between carrier profiles and annealing conditions. Using photoperturbation-controlled SCM, we may have a chance to clearly observe the evolution of carrier profiles produced by SA and post-SA furnace annealing (FA). In this work, we have employed front-wing conductive probes to perform photoperturbation-controlled SCM and studied the variation of the carrier profiles before and after post-SA FA at 500 degree C. Studied samples were p/n junctions formed by ion implantation at low energies. SA processes were performed at 1050 degree C in nitrogen ambient. The experimental results indicate that the electrical junction formed by SA is unstable. The SCM images clearly show that post-SA FA can induce the electrical junction narrowing in two dimensions. For junction stability, our experimental results revealed that the lateral electrical junction is more unstable than the vertical junction. However, secondary ion mass spectroscopy has revealed that dopant diffusion can be negligible for the FA temperature below 520 degree C. Interstitial-type point defects generation/recombination associated with dopant deactivation may play an important role of junction width modification during the following low temperature processes. In addition to electrical junction narrowing, we have also observed enhanced dopant activation from the shallower region of the same sample. In the shallower implanted region, vacancy-type point defects are dominant and able to recombine with the interstitial atoms nearby the vacancy site, enhancing carrier concentration during the post-SA FA at low temperatures. The physical mechanism and the stability of electrical junctions formed by high temperature processes will be discussed. |