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Kelvin probe force microscopy for characterization of semiconductor devices and processes
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1996
Year
Aluminium NitrideEngineeringMicroscopyLateral Impurity ProfileSemiconductorsSemiconductor DevicesElectron MicroscopyNanometrologySpatial ResolutionMolecular Beam EpitaxyMaterials ScienceMaterials EngineeringElectrical EngineeringNanotechnologySemiconductor MaterialIon Implantation MaskMicroelectronicsSurface CharacterizationScanning Probe MicroscopySurface ScienceApplied PhysicsScanning Force MicroscopyElectron Microscope
The study investigated the spatial resolution of Kelvin probe force microscopy using cleaved Al₀.₃Ga₀.₇As/GaAs structures. Kelvin probe force microscopy was employed to characterize Al₀.₃Ga₀.₇As/GaAs multilayers and Si‑pn junctions, and to extract a lateral impurity profile beneath an ion‑implantation mask by calibrating the two‑dimensional potential image with spreading‑resistance measurements. The technique resolved a 40‑nm Al₀.₃Ga₀.₇As layer with a 15‑mV potential contrast, showed sensitivity to Al mole fraction, enabled two‑dimensional mapping of Si‑pn structures, revealed that illumination narrows the depletion layer, and demonstrated that the measured potential reflects the surface band structure.
Kelvin probe force microscopy was applied to the characterization of Al0.3Ga0.7As/GaAs multilayer structures and Si-pn structures. The spatial resolution of Kelvin probe force microscopy measurement was investigated using cleaved Al0.3Ga0.7As/GaAs structures. A 40-nm-thick Al0.3Ga0.7As layer was resolved with potential difference of 15 mV. It was found that the measured potential is sensitive to the Al mole fraction for AlGaAs. Two-dimensional delineation of Si-pn structures was successfully carried out on the topmost and the cleaved surfaces. A decrease of a depletion-layer width with increasing the intensity of light illuminating the sample was observed. It was confirmed through investigating illumination effects on various kinds of structures that the measured Kelvin probe force microscopy potential reflects the surface band structure of the sample. A lateral impurity profile under the ion implantation mask was extracted from the two-dimensional potential image obtained on the cleaved pn junction by calibrating with the impurity concentration profile measured by the spreading resistance method.