Accurate profiling of PN junction carrier concentration by scanning nonlinear dielectric microscopy (SNDM)

Abstract

We used scanning nonlinear dielectric microscopy (SNDM) to diagnose doping integrity in a transistor. Non-linear capacitance (dC/dV) profiling and pinpoint capacitance-voltage analysis were implemented by SNDM and the results clearly discriminated a depletion layer in a n/sup +//p junction and tailing of the carrier distribution due to out-diffusion of dopants. The carrier state analysis was applied to n/sup +//p/n/sup +/ transistor-channel structures formed with different process parameters. An increase in the n/sup +/ activation temperature from 800 to 950/spl deg/C caused narrowing of the p-type region in the channel. A decrease in the substrate doping concentration from 10/sup 18/ to 10/sup 17/ cm/sup -3/ caused depletion of the entire channel when the gate length was less than 200 nm.