2-DIMENSIONAL DELINEATION OF SHALLOW JUNCTIONS IN SILICON BY SELECTIVE ETCHING OF TRANSMISSION ELECTRON-MICROSCOPY CROSS-SECTIONS

The method of junction delineation with thickness fringes in selectively chemical etched transmission electron microscope cross sections is demonstrated on a few examples. Arsenic-doped source and drain regions of metal-oxide-silicon transistors were delineated at a concentration level of about 1 X 10(18) cm-3 both in the as-implanted state and after 900-degrees-C annealing. Calibration was performed with one-dimensional secondary ion mass spectroscopy dopant profiles whereas process simulation was used to examine the experimental two-dimensional results. The lateral extent of the dopant surface concentration at 1 X 10(19) cm-3 under the transistor gate after 900-degrees-C annealing corresponded to the n + /n transition region previously detected by scanning tunneling microscopy. Boron and arsenic junctions were simultaneously delineated in a bipolar transistor.