Micro-Raman spectroscopy as a tool for the characterization of silicon carbide in power semiconductor material processing

Biasio, Martin De; Kraft, Martin; Schultz, Matthias; Göller, Bernhard; Sternig, D.; Esteve, Romain; Roesner, Malte

doi:10.1117/12.2259930

Cited by 1 publication

(2 citation statements)

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“…Thus, we classified the LO peak as the longitudinal optical mode (LO mode) of the epitaxial layer and the LOPC peak as the longitudinal optical phonon-plasmon coupled mode (LOPC mode) of the heavily doped substrate, respectively. Druy et al arrived at similar conclusions [16]. Figure 4a-c indicate that the distribution of the LO peak along the depth direction had a narrower width for smaller pinholes, which implies a stronger ability to distinguish multilayer structures for smaller pinholes.…”

Section: Depth Profiling Set-upssupporting

confidence: 58%

“…Zuk destructively pretreated the sample and obtained the damage distribution of high-energy ion-implanted 6H-SiC by confocal Raman spectroscopy on the processed slope, which requires rigorous and complex sample pretreatment and the sample cannot be re-used or further processed after the test [15]. De Biasio demonstrated the use of Raman spectroscopy for the determination of carrier concentrations in epitaxial layers and substrates in n-type 4H-SiC obtained by doping during epitaxial growth without a detailed explanation of the overlap of the longitudinal optical (LO) mode and the longitudinal optical phonon-plasmon coupled (LOPC) mode [16]. Tao Liu et al studied the phenomenon of photo-generated carriers excited by ultraviolet light (325 nm line) and calculated the carrier concentrations of the epitaxial layer [17].…”

Section: Introductionmentioning

confidence: 99%

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Depth Profiling of Ion-Implanted 4H–SiC Using Confocal Raman Spectroscopy

Song

Liu

et al. 2020

Crystals

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For silicon carbide (SiC) processed by ion-implantation, dedicated test structure fabrication or destructive sample processing on test wafers are usually required to obtain depth profiles of electrical characteristics such as carrier concentration. In this study, a rapid and non-destructive approach for depth profiling is presented that uses confocal Raman microscopy. As an example, a 4H–SiC substrate with an epitaxial layer of several micrometers thick and top layer in nanoscale that was modified by ion-implantation was characterized. From the Raman depth profiling, longitudinal optical (LO) mode from the epitaxial layer and longitudinal optical phonon-plasmon coupled (LOPC) mode from the substrate layer can be sensitively distinguished at the interface. The position profile of the LOPC peak intensity in the depth direction was found to be effective in estimating the thickness of the epitaxial layer. For three kinds of epitaxial layer with thicknesses of 5.3 μm, 6 μm, and 7.5 μm, the average deviations of the Raman depth analysis were −1.7 μm, −1.2 μm, and −1.4 μm, respectively. Moreover, when moving the focal plane from the heavily doped sample (~1018 cm−3) to the epitaxial layer (~1016 cm−3), the LOPC peak showed a blue shift. The twice travel of the photon (excitation and collection) through the ion-implanted layer with doping concentrations higher than 1 × 1018 cm−3 led to a difference in the LOPC peak position for samples with the same epitaxial layer and substrate layer. Furthermore, the influences of the setup in terms of pinhole size and numerical aperture of objective lens on the depth profiling results were studied. Different from other research on Raman depth profiling, the 50× long working distance objective lens (50L× lens) was found more suitable than the 100× lens for the depth analysis 4H–SiC with a multi-layer structure.

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Section: Depth Profiling Set-upssupporting

confidence: 58%