Effects of Boron Doping on the Surface Modification and Defect Evolution of Silicon Induced by Proton Implantation and Annealing

Abstract

Ultra-thin silicons can be obtained using SMART CUT technology, but there is a lack of systematic research on the effect of boron doping. This paper reports the effects of boron doping on surface modification and defect evolution. Monocrystalline silicon samples with different concentrations of boron doping were implanted to 3.5×1017H+/cm2 using a 1.52 MeV high fluence proton accelerator and annealed at 300, 400, and 550 ℃. The annealed samples were analyzed by non-contact optical profilometry, Raman spectroscopy, SEM, and TEM. The results show that appropriate boron doping can reduce the surface roughness of the exfoliated samples; excessive boron doping leads to a significant increase in surface roughness (~525 nm) and produces a step-like morphology. Boron doping leads to changes in the type, concentration and dissociation temperature of hydrogenation defects during implantation. These changes result in the width of damage band changes vary with doping concentration. The density and diameter of the hydrogenated extended defects also changed,which results in the surface modification of samples, such as the change of the surface morphology and substrate roughness. In the end of the paper, the correlation between surface morphology and internal damage for different concentrations of boron doping.

Keywords: proton beam implantation, Monocrystalline silicon, Raman, TEM, boron doping