Impact of mechanical scratches on the structural, thermal, and electronic properties of monocrystalline silicon

Abstract

The influence of intrinsic and extrinsic defects on the electronic, thermal, and structural properties of monocrystalline silicon was investigated using photothermal radiometry (PTR), photoacoustic (PA) methods, x-ray diffraction (XRD), and electrical characterization. A p-type silicon wafer (ρ = 0.005 Ω cm) was analyzed as a complete wafer, and a 1 cm2 sample was cut from the wafer center. The 1 cm2 silicon sample was examined before and after introducing one and two orthogonal central scratches. Mechanical defects were characterized by atomic force microscopy (AFM) to determine scratch width and depth. AFM measurements identify localized surface buckling and topographic deformation. In damaged regions, PTR and PA mapping revealed a decrease in thermal diffusivity from 0.97 to 0.15 cm2s−1. XRD analysis showed a slight shift of the (400) diffraction peak from 69.124° to 69.146° and an increase in full width at half maximum from 0.049° to 0.060°, indicating lattice distortion. Structure refinement of diffraction patterns showed that the lattice strain increased from 0.103% before scratching to 0.295% after scratching. Electrical resistivity measurements using the van der Pauw method indicated increased disorder, reducing measurement reliability in cut samples due to structural non-homogeneity and disruption of the electron mean free path. The results establish a correlation between extrinsically induced mechanical lattice disorder and intrinsic defects due to carrier distribution, which causes the degradation of thermal and electronic transport, and highlight the sensitivity of PTR and PA techniques for the non-destructive detection of surface damage in silicon wafers.