Design concepts of a newly developed multi-wavelength, micro Raman spectroscopy system for non-contact and non-destructive characterization of semiconductor materials and its performance are introduced. The system is designed to sequentially measure Raman signals under various excitation wavelengths without sample movement or calibration between switching of excitation wavelengths. Area maps of Raman shift, full-width-at-half-maximum (FWHM) and intensity from an advanced memory device were generated and stacked in the order of wavelength (or penetration depth). This unique display of Raman shift, FWHM and intensity, corresponding to crystalline stress, crystallinity and/or scattering probability provides powerful insights into the sample under characterization.

Multiwavelength room temperature photoluminescence (RTPL) and Raman spectroscopy were proposed as in-line monitoring techniques for characterizing the dielectric/Si interface. As an application example, ∼7.0 nm thick ultra-thin SiO 2 films on 300 mm Si wafers, prepared by various oxidation techniques and conditions, were characterized using multiwavelength RTPL and Raman spectroscopy. Specifically, overall quality of the ultra-thin SiO 2 /Si interface (including passivation characteristics) and Si lattice stress beneath SiO 2 films are investigated. The overall SiO 2 /Si interface quality was seen to be very dependent on oxidation technique and process conditions. Within wafer and wafer-to-wafer variations of SiO 2 /Si interface quality were successfully characterized by RTPL and Raman spectra measurements. For electrical analysis of SiO 2 /Si-based structures, non-contact corona charge-based, in-line (capacitance-voltage (C-V) and stress induced leakage current (SILC)) measurements were performed and compared with RTPL and Raman characterization results. Surprisingly, significant variations in RTPL intensity at and near the corona charge-based measurement sites, indicated that the corona-based electrical measurement technique, though non-contact, was indeed invasive. The effect of corona-charge based electrical measurements on SiO 2 /Si interface was permanent and even clearly visible from the back side of the wafer. RTPL intensity variations at and near the measurement sites remained, even after a forming gas anneal. As devices scale to smaller size and complexity of device structures increase, the importance of proper understanding and control of the dielectric/Si interface is increasing. Advanced metal-oxidesemiconductor (MOS) and metal-insulator-semiconductor (MIS) devices employ ultra thin dielectric gate layers. The physical dimensions are in the range of single digit to double digit nanometers. The effective oxide thickness (EOT) is significantly less than 10 nm. Pure SiO 2 or combinations of SiO 2 and SiN layers are typically used as gate dielectrics. Materials with high dielectric constant (high-k dielectrics) and metal gates are also frequently used, depending on chip design.Conventional interface characterization techniques, such as high resolution cross-sectional transmission electron microscopy (HRX-TEM), Auger electron spectroscopy (AES), secondary ion mass spectroscopy (SIMS), X-ray photoelectron spectroscopy (XPS) and noncontact electrical measurement tools (for example, I-V, C-V and carrier life-time measurements) are either destructive or invasive (including methods which are non-contact, but impact dielectric/Si interface quality).1-3 The purpose of all these characterization techniques is to gain useful insights into dielectric/Si in various dimensions or aspects. While the conventional characterization techniques provide very useful information on many properties of the dielectric/Si interface, they appear unable to provide additional clues to some puzzling dielectric/Si interface problems....

Ultra-shallow boron implanted ͑B + 1 keV 1.0 ϫ 10 15 cm −2 ͒ n-type Si wafers were prepared and characterized by multiwavelength Raman and photoluminescence ͑PL͒ spectroscopy before and after rapid thermal annealing ͑RTA͒. The Raman and PL characterization results were compared with sheet resistance from four point probe measurements and boron depth profiles from secondary ion mass spectroscopy. We have found a very strong correlation between the rapid, non-contact optical characterization results and important parameters of ultra-shallow junctions ͑USJs͒ obtained from conventional invasive techniques. Ultraviolet Raman was very sensitive to subsurface ͑ ϳ5 nm͒ B profiles near or above the solid solubility ͑ Ͼ 1 ϫ 10 20 cm −3 ͒ of B in Si. Visible wavelength excitation PL indicated the presence of significant levels of nonradiative recombination centers beyond the USJ depth and implant end-of-range damage even after RTA. Multi-wavelength Raman and PL are found to be very promising as complementary and/or alternative diagnostic metrology tools for implant process control and in-line device performance screening.For high performance and low power consumption, miniaturization of devices is essential. Physical dimensions and all design parameters have to be scaled down while keeping the dopant concentration of the source/drain region higher than ever, often higher than the solid solubility of dopants in thermal equilibrium. 1 The ultrashallow junction ͑USJ͒ fabrication process is one of the most critical, yet extremely challenging, areas in advanced device research and development ͑R&D͒ and manufacturing beyond 45 nm technology nodes. 1-9 Various types of millisecond annealing techniques, including flash annealing 2,6,7 and laser spike anneal, 10 have been proposed and implemented in production. The quality of USJs, including the degree of electrical activation and dopant profiles of USJ implanted Si, after implant activation and rapid thermal annealing ͑RTA͒ has been monitored by four point probes and secondary ion mass spectroscopy ͑SIMS͒. 1-9 These traditional USJ characterization techniques require either physical contact or destructive analysis. The existence of electrically active defects, dopants in excess of solid solubility, interstitial dopants around USJs, and junction leakage often lead to unrealistic conclusions. No easy, reliable, and practical USJ characterization methods are available at present, even though several novel characterization techniques, such as micro-four point probes and non-contact sheet resistance estimation using carrier spreading measurements, have been proposed. 7,11 For proper characterization of USJs, the development of alternative, complementary, subsurface characterization techniques to augment traditional techniques, and their introduction to advanced device R&D and the manufacturing community, is essential. Noncontact and non-destructive in-line characterization and/or monitoring methods are strongly desired for fast feedback of characterization results and the reduction of m...

Three-dimensional stress development was observed in silicon surrounding the Cu-filled through-silicon via (TSV) structures undergoing the thermal annealing process. We show here, using a multiwavelength micro-Raman spectroscopy system, that the behavior of stress development in silicon after annealing step is dependent on the initial stress state as well as the geometry and directionality of the TSV array. The warping of stress curve for postannealed state with a reference of preannealed state is distinctively observed. Furthermore, the introduction of stress-free point is also attributed to the destructive stress interaction from different geometry and direction and initial stress state.

Three dimensional (3D) stress distributions in Si, surrounded by copper (Cu) filled through silicon vias (TSVs) with various dimensions and pitches, are non-destructively characterized and stress contour maps generated at different depths using a long focal length, polychromator-based, multi-wavelength micro-Raman spectroscopy system. It was found that stress and crystallinity in Si (in both planar and depth directions) was strongly influenced by the proximity to a TSV, as well as, the dimensions of the TSV. In addition to characterizing semiconductor materials, Multi-wavelength micro-Raman spectroscopy was extremely effective for characterizing process-induced variations in crystalline stress and quality where 3D interconnects and packaging technology is introduced.