Extracting active dopant profile information from carrier illumination power curves

Abstract

Two dimensional dopant and carrier profiles obtained by scanning capacitance microscopy on an actively biased cross-sectioned metal-oxide-semiconductor field-effect transistorThe carrier illumination ͑CI͒ method is an optical nondestructive technique primarily used today for the in-line monitoring of ultrashallow doping profiles in advanced complementary metal oxide semiconductor devices. A CI measurement is basically a differential probe laser reflectivity measurement providing ͑indirect͒ information on the underlying active dopant structure. As the signal depends on the doping density as well as the junction depth, no unique answer can be extracted from a single measurement. When analyzing power curves ͑i.e., the CI signal as a function of the power of the pump laser͒, it is shown that the shape of the power curves is ͑simultaneously͒ extremely sensitive to many different physical parameters, such as junction depth ͑angstrom͒, carrier peak density ͑10%͒, profile steepness ͑few nm/ decade͒, etc. In this work, we present a detailed interpretation and deconvolution method enabling the independent extraction of the peak carrier density and the junction depth for ͑unknown͒ chemical vapor deposition-grown box-like profiles ͑with 1-2 nm/ decade steepness͒. The method is based on the exploitation of two characteristics of the power curve, namely its signal value at a particular ͑arbitrary͒ power and the power at which an inflection point ͑second derivative zero͒ occurs. The physical interpretation on this approach will be presented and is supported by extensive three-dimensional axisymmetric numerical simulations.

Monitoring of Dose Dependent Damage in MeV Energy Hydrogen Implanted Silicon by Photo-Modulated Reflectance Measurements

“…To date the Photo-modulated-reflectance (PMR) technique has been successfully applied for doping concentration monitoring and shallow junction depth profiling in silicon [4]. Also, detailed description and modeling of the PMR process has been presented [5].…”

Impact of band gap narrowing and surface recombination on photoelectrothermal modulated optical reflectance power curves

“…The pumpinduced modulated optical reflectance is then measured by a second laser, the probe laser. In order to obtain more information on the sample, an external parameter ͑the pump laser modulation frequency, 3 the separation between the two lasers, 4,5 the pump laser irradiance, [6][7][8] etc.͒ can be varied. Carrier Illumination™ ͑CI͒ ͑Ref.…”