Non-Contact and Non-Destructive Characterization Alternatives of Ultra-Shallow Implanted Silicon p-n Junctions by Multi-Wavelength Raman and Photoluminescence Spectroscopy

Abstract

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...

Noncontact Monitoring of Activation and Residual Damage of Dual Implanted Silicon Using Room Temperature Photoluminescence

“…2,3,5,[9][10][11] Figure 3a shows 650 nm excited RTPL spectra from the 75 s annealed wafers at temperatures between 350…”

Ultra-Thin SiO2/Si Interface Quality In-Line Monitoring Using Multiwavelength Room Temperature Photoluminescence and Raman Spectroscopy

“…The details of the system and its applications have been published elsewhere. [7][8][9][10] No measurable RTPL signal was observed from most of SiO 2 /Si wafers under 532 nm excitation. For 650 nm excitation, the laser power at the wafer surface was 20 mW and exposure time was 1.0 s per point.…”

Room Temperature Photoluminescence Characterization of Low Dose As+ Implanted Si after Rapid Thermal Annealing

“…17,18 Promising results of RT spectroscopic PL studies on ultra-shallow and shallow implanted junctions have also been reported previously. [19][20][21][22] RTPL characterization of non-radiative defect density on surfaces and interfaces of Si with native, anodic and thin thermal oxides, have been extensively studied under ultra violet (UV) excitation in vacuum by Timoshenko et al 23 In this paper, RTPL was investigated using implant annealed Si samples, which showed electrical performance variations, even though all the (implant and anneal) process conditions are substantially the same. The major objectives are to understand the main cause of electrical performance variations and develop a practical implant monitoring technique for CMOS image sensor process control.…”

“…Interband RTPL has also been used in monitoring surface and interface defects during oxidation, epitaxial Si quality and electrical activation of low energy implanted Si after RTA. [17][18][19][20][21][22][23] The effective lifetime in semiconductors is important to the operation of some semiconductor devices such as solar cells, pn junctions, bipolar junction transistors and thyristors, but it is generally difficult to decompose into bulk recombination lifetime and surface recombination velocity. 25,26 Correlation lifetime and PL intensity near 1.1 μm has been studied in bulk Si and SOI (silicon-on-insulator) wafers under various excitation wavelengths.…”