Precise Comparison of Two-dimensional Dopant Profi les Measured by Low-voltage Scanning Electron Microscopy and Electron Holography Techniques

As the size of metal-oxide-semiconductor field-effect transistors (MOSFETs) shrinks to nanoscale, the precise and reliable dopant profiling in shallow junctions has become important for device modeling and operation (Bertrand et al.,2004). Secondary ion mass spectrometry (SIMS) and spreading resistance profiling are widely used as practical characterization techniques to reveal one-dimensional (1D) dopant distribution in p-n junctions. However, both techniques are not sufficient to delineate the accurate and reliable lateral dopant distribution of nanoscaled MOSFETs devices. Two-dimensional (2D) dopant profiling methods such as chemical etching delineation (CED) (Eo et al., 2004; Shaislamov et al., 2008), scanning capacitance microscopy (SCM) (Zavyalov et al., 1999; Morita, 2007), electron holography (EH) (Völkl et al., 1998; Tonomura, 1999), and low-voltage scanning electron microscopy (LV-SEM) (Venables & Maher, 1996; Elliott et al., 2002; El-Gomati et al., 2005) have been received a lot of attention due to their high spatial resolution. The CED method is based on the chemical etching of the specimen containing p-n junctions, where etching rate depends on the difference of dopant type and concentrations. This method is favored due to its quick and simple experimental procedure. However, due to the difficulty in controlling the etching process, this technique does not provide reproducibility and quantitative information. On the other hand, the SCM technique which is based on the atomic force microscope has been shown to be useful for the quantitative 2D dopant profiling with good sensitivity and wide dynamic range of 10~10 atom/cm. This technique can extract the 2D carrier profi les in semiconductor devices by mapping the local capacitance variation (dC/dV) between Precise Comparison of Two-dimensional Dopant Profi les Measured by Low-voltage Scanning Electron Microscopy and Electron Holography Techniques