Journal of Applied Physics · 2002 · 145 citations · 14 references
EngineeringElectrical EngineeringMaterials ScienceElectronic MaterialsSemiconductor DevicesSemiconductor MaterialsDevice CharacterizationDopingElectron MicroscopyMetal-oxide-semiconductor Field-effect TransistorsP-n JunctionsSemiconductor PhysicsContrastDopant ProfilingDoped SemiconductorsDoping Profile AnalysisDoping ProfilesScanning Electron MicroscopySemiconductor CharacterizationSemiconductor Doping Profiles
The study presents a detailed SEM-based dopant profiling of silicon, offering guidelines for optimal operating conditions to maximize contrast. SEM secondary‑electron imaging was applied to diverse silicon test structures and MOSFETs, with contrast examined as a function of temperature, bias, and optimized operating conditions. Contrast from p‑doped silicon as thin as 1 nm and with concentrations below 10^16 cm⁻³ was detected, showing that built‑in voltages and resulting patch fields dominate the secondary‑electron contrast.
This article describes the results of a detailed study of semiconductor dopant profiling with the scanning electron microscope (SEM) using secondary electrons. The technique has been applied to a wide variety of doped silicon test structures as well as a metal–oxide field-effect transistor. We have demonstrated that contrast can be detected from p-doped regions as thin as one nanometer across. Contrast can also be measured from p-type regions with doping concentrations less than 1016 cm−3. We have studied the variation of doping contrast with specimen temperature and with a bias applied across a p-n junction in situ in the SEM. These experiments demonstrate that doping contrast is mainly due to the built-in voltages in semiconductor devices which result in local fields (patch fields) outside the specimen which influence the number of secondary electrons detected. A concise set of guidelines is provided for users of this technique, including the optimum SEM operating conditions that should be used for maximum contrast.
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