Characterization of accumulation layer capacitance for extracting data on high-k gate dielectrics

A new parameter extraction technique has been outlined for high-k gate dielectrics that directly yields values of the dielectric capacitance C_di, the accumulation layer surface potential quotient, β_acc, the flat-band voltage, the surface potential _s, the dielectric voltage, the channel doping density and the interface charge density at flat-band. The parallel capacitance, C_p(= C_sc + C_it), was found to be an exponential function of φ_s in the strong accumulation regime, for seven different high-k gate dielectrics. The slope of the experimental InC_p(φ_s) plot, i.e., Β_acc , was found to depend strongly on the physical properties of the high-k dielectric, i.e., was inversely proportional to [(φ_bm*/m)^1/2K/C_di], where φ_b is the band offset, and m* is the effective tunneling mass. Extraction of Β_acc represented an experimental carrier confinement index for the accumulation layer and an experimental gate-dielectric direct-tunneling current index. Β_acc may also be an effective tool for monitoring the effects of post-deposition annealing/processing.