PLASMA IMMERSION ION-IMPLANTATION FOR MATERIALS MODIFICATION AND SEMICONDUCTOR PROCESSING - CARBON NITRIDE FILMS AND POLY-SI TFTS HYDROGENATION

This paper provides a review of the recent research on plasma immersio n ion implantation (PIII) for materials modification and semiconductor processing performed by the Plasma Science group al Northeastern Univ ersity, The results from two PIII experiments: thin carbon films modif ication by nitrogen implantation and the hydrogenation of polycrystall ine silicon (poly-Si) thin film transistors (TFTs) for defect passivat ion are presented. For the nitrogen implanted carbon films (CNx), low energy PIII (similar to 2 keV) formed covalent carbon-nitrogen bonds i n the carbon films and reduced the interfacial tension between the fil ms and the substrate which suggest an improvement in adhesion. Convent ional ion beam (IB) nitrogen implantation produced CNx films with less nitrogen to carbon ratio [N]/[C] and significant surface damage. In t he hydrogenation of poly-Si TFTs experiment, a high hydrogenation effi ciency was achieved by low energy (1 keV) and high dose rate (similar to 10(16)/cm(2) s) implantation using an inductively coupled plasma (I CP) source. Significant improvement in the device parameters (e.g., le akage current, effective mobility, threshold voltage, and subthreshold slope) was achieved in a fraction of the time needed by other hydroge nation methods.