Micro-Raman Characterization of Cluster Carbon Implanted Si before and after Rapid Thermal Annealing

Abstract

To meet various physical property requirements of materials for advanced high performance devices, combinations of Si1-xGex and Si:C have been introduced for strain control in PMOS and NMOS regions of devices. Two types of carbon (C) doping techniques have been explored for tensile stress generation in the NMOS device region. Carbon-doped Si epitaxial growth with C doping and C-implantation into Si are two major approaches. Carbon implanted Si requires annealing for recrystallization, damage recovery and tensile strain control. Strain characterization, monitoring and control are as important as material preparation. Non-contact, non-destructive strain and crystallinity characterization techniques with high spatial resolution and virtual depth profiling capability are strongly desired for in-line monitoring. In this study, we report the micro-Raman characterization results on cluster C-implanted Si for tensile strain generation before and after various rapid thermal annealing (RTA) techniques and conditions. Phosphorous ion clusters (P4) (8 keV, 4x1015 cm-2) were implanted with carbon ion clusters (C7) targeting 1.3% and 1.5% flat C profile (~50 nm from the surface). Various excitation wavelength laser beams were used in Raman characterization for virtual strain depth profiling. Flash anneal (fRTP) at 1200oC and impulse spike anneal (iRTP) at 1000oC and 1050oC were used as annealing conditions. As-implanted Si wafers showed almost no Raman signal due to the crystalline lattice damage from high dose cluster ion beam implantation. After RTA of implanted Si wafers under different techniques and conditions, significant broadening and shift of Raman peaks towards the lower wavenumber side was measured, indicating the presence of tensile strain and crystallinity alterations. X-ray diffraction (XRD), secondary ion mass spectroscopy (SIMS) depth profiling and transmission electron microscopy (TEM) analysis results will be reported along with multiwavelength micro-Raman characterization results. Figure 1 shows 363.8nm excited micro-Raman spectra from reference Si and cluster C implanted Si wafers before and after rapid thermal annealing (RTA). Figure 1