Developments in Raman Spectroscopy for Ion Implant Monitoring

As part of a strategy for development of in situ process monitoring for VLSI technology we are evaluating a number of optical techniques applicable to implantation and annealing processes. Techniques with potential for non-destructive characterization of patterned production wafers, rather than test wafers, are of primary interest. Consequently, the techniques to be considered must (i) be non-contact and non-contaminating; (ii) have high spatial resolution; (iii) provide rapid real time analysis; and (iv) use equipment that is adaptable for automatic or turn-key operation. Raman spectroscopy meets these criteria and the technique is well suited for studying materials for silicon technology (1). Features in the Raman phonon spectrum of implanted silicon can provide information on ion-damage prior to annealing or on the activation and distribution of dopant after annealing (2). In this paper we investigate the limits to the dose and energy of boron implants which can be detected by Raman spectroscopy.