Author:

Keywords:

Science & Technology, Physical Sciences, Physics, Applied, Physics, CARRIER ILLUMINATION, DEVICE SIMULATION, SILICON, SEMICONDUCTORS, TEMPERATURE, ABSORPTION, MODEL, 01 Mathematical Sciences, 02 Physical Sciences, 09 Engineering, Applied Physics, 40 Engineering, 49 Mathematical sciences, 51 Physical sciences

Abstract:

Carrier illumination (CI) is a photoelectrothermal modulated optical reflectance (PMOR) technique for the one dimensional active doping profile characterization of ultrashallow junctions. The specificity of CI as a PMOR technique is to exploit the probe differential reflectance nonlinearity as a function of the pump laser irradiance (104 - 106 W cm2). The probe differential reflectance as function of the pump power is called a power curve, and its interpretation provides information on the underlying active doping profile. In a previous work [F. Dortu, J. Vac. Sci. Technol. 24, 375 (2006)], the independent extraction of the active doping concentration (N) and the metallurgical junction (Xj) of a chemical vapor deposited boxlike profile was based on two features of the power curve, namely, the inflexion power and the signal at end of range power. However, this method suffers from the difficulty to extract accurately the second derivative and has a limited extraction range (Xj =20-40 nm, N= 1019 - 1020 cm3). In the present work, we present a method making use of the power curve's first derivative at low and high illumination powers. This method, in principle, allows a much broader extraction range (Xj =10-70 nm, N= 1018 - 1020 cm3) provided that the signal time dependence due to the native silicon oxide charging under intense illumination is taken into account properly. The present work is supported by a two-layer diffusionless nonlinear analytical model, which provides the basic insights of the method, and three dimensional axisymmetric numerical simulations in the framework of the drift-diffusion equations. A procedure to remove the time dependent charging effect is also presented. © 2007 American Institute of Physics.