Materials Science Forum, Vol.353-356, 559-562, 2001
Techniques for depth profiling of dopants in 4H-SiC
Three different methods for measuring the depth distribution of dopants in 4H-SiC have been investigated: (I) Spreading Resistance profiling (SRP), (2) Scanning Capacitance Microscopy (SCM) and (3) Scanning Electron Microscopy (SEM). The investigated samples included p- and n-type epitaxial layers grown by vapor phase deposition with doping concentrations of 10(16)-10(20) cm(-3). Also p(+)n implanted profiles using a combination of Al and B multi-energy implantations were studied. All techniques were able to provide doping profiles qualitatively corresponding to secondary ion mass spectrometry (SIMS) data. The SRP results suggest a lower limit of the p-doping concentration below which the ohmic contact between the probe tip and sample becomes more Schottky-like. The magnitude of the SCM signal corresponds well to the chemical doping profile except in the depleted region surrounding the metallurgical junction of the p(+)n structure.
Keywords:dopant activation;dopant profile;scanning capacitance microscopy (SCM);SEM;Spreading Resistance profiling (SRP)