Journal of Vacuum Science & Technology B Microelectronics and Nanometer Structures Processing Measurement and Phenomena · 1996 · 47 citations · 0 references
EngineeringMaterials EngineeringMaterials ScienceElectronic MaterialsSemiconductor DevicesSemiconductor MaterialsDopingElectron MicroscopyElectronic Material CharacterizationP-n JunctionsSemiconductor Device MaterialsSemiconductor PhysicsContrastDopant ProfilingDoping In NanostructuresDoping ProfilesScanning Electron MicroscopySecondary Electron EmissionSemiconductor CharacterizationSemiconductor Doping Profiles
The study optimized experimental conditions—microscope and material parameters—to maximize secondary electron contrast in silicon p/n junctions. Doping‑dependent secondary electron contrast was observed, maximized at ~1 kV with a through‑lens detector, correlating well with SIMS for boron‑doped p+/n junctions down to 10¹⁷ cm⁻³, but not for n+/p, and can be used to map 2‑D dopant profiles when calibrated against a 1‑D profiling method.
Doping-dependent contrast in secondary electron images of p/n junctions in silicon obtained in a field-emission scanning electron microscope was observed and characterized. The optimum experimental conditions for observing this ‘‘electronic’’ contrast were established by investigating the effect of microscope and material parameters on the magnitude of the contrast. The contrast between the bright p-type areas and the darker n-type areas was maximized at an accelerating voltage of ∼1 kV, and when a through-the-lens detector configuration was employed. Secondary electron contrast profiles of boron doped p+/n junctions in silicon showed a good correlation with secondary ion mass spectroscopy depth profiles of the atomic concentration down to the 1017 cm−3 level. However, similar results were not obtainable for n+/p junctions. It is demonstrated that this contrast effect may be exploited for obtaining two-dimensional dopant profiles directly from secondary electron images of p+/n junctions provided that the technique is empirically calibrated against a one-dimensional dopant profiling method.