Two-dimensional carrier profiling of a 0.4 μm CMOS device by Schottky SCM

By combining metal-semiconductor C-V profiling techniques with two-dimensional scanning probe microscopy, a new technique for 2D delineation of semiconductor doping profiles based on the measurement of the local Schottky contact capacitance has been developed. When a metal probe is brought into contact with a semiconductor, a space-charged depletion region and therefore a capacitor is formed at the junction. By applying a small AC voltage, the voltage derivative of the contact capacitance can be measured with a lock-in amplifier. The amplitude of the derivative signal is a function of the carrier concentration, and the sign gives the type of carrier. The local contact capacitance-voltage (C-V) measurements on standard doping samples show a monotonic behaviour of capacitance derivative (dC/dV) versus doping concentration over a range from 10¹⁴ cm^-3 to 10 ¹⁸ cm^-3. This work concentrates on the 2D doping profiling of a 0.4 μm MOSFET. The results demonstrate that this technique is capable of quantitative 2D characterization of semiconductor devices