Search

Scanning nonlinear dielectric microscopy was used to diagnose doping integrity in a transistor channel. The carrier state at various points in a pn junction was defined as n-type, p-type, or depletion through nonlinear capacitance (dC/dV) profiling and pinpoint capacitance–voltage analysis. Carrier state analysis was applied to the n+/p/n+ transistor channel of structures with different process parameters. An increase in the n+ activation temperature from 800 to 950 °C caused shrinkage in channel length of the p-type region. Decreasing the substrate acceptor concentration from 1018 to 1017 cm−3 caused depletion of the entire channel when the gate length was less than 200 nm.

Work function control of metal transistor gates was implemented with Al–Ni alloys. In addition to obtaining conventional capacitance-voltage (C-V) measurements to evaluate the work function, we microscopically characterized the work function distribution through scanning Maxwell-stress microscopy (SMM). The C-V curves of the Al–Ni alloys that we investigated exhibited work functions approximately between those of Al and Ni. The SMM analysis revealed that an Al–Ni alloy fabricated by the interdiffusion of a Ni∕Al stack had a significant nonuniformity of the work function. This nonuniformity correlated with degradation of the C-V characteristics for interdiffused Al–Ni alloys.