Application of an ultrahigh vacuum vertical batch reactor for selective chemical vapor deposition of hemispherical grain (HSG) polysilicon on planar and three-dimensional crown capacitor storage nodes is investigated. Comparison between selective MSG and other nonselective alternatives is drawn. An optimum pre-MSG clean chemistry (with 60 Angstrom overall oxide etch), suitable for 256 MB and 1 GB application, for both multi- and single tank wafer clean modules is recommended. This clean method maintains the integrity of the starring a-Si (>5% of the original a-Si thickness) prior to HSG transformation. Contamination issues related to the tool, preclean module, and the processing ambient are explored. Factors impacting within wafer and wafer-to-wafer reflectance and capacitance uniformity and the effect of particles and crystallization defects on HSG transformation are evaluated. Defect formation mechanisms and ways of minimizing defect density are also included. Effects of critical processing parameters on MSG grain characteristics in order to obtain maximum area enhancement factor and highest C-min/C-max ratio for high density application (256 MB, 1 GB, and beyond) is explored in depth. Post-MSG gas phase doping (800 degrees C for 300 s) to achieve a C-min/C-max ratio of >0.95 and its effect on surface roughness of HSG transformed a-Si film is investigated.