Room Temperature Photoluminescence Characterization of Silicon Wafers for In-Line Monitoring Applications

Abstract

Performance variations and yield loss in advanced Si devices are closely related to the quality of the semiconductor surface and interfaces. These are very significant factors for successful development of advanced devices. In addition, proper implementation of manufacturing processes is critical as devices scale to smaller size and complexity of device structures increase. The importance of proper understanding and control of surface cleaning and passivation of silicon and dielectric/Si interface quality, is more important than ever. Characterization techniques for determining the effectiveness of Si cleaning, surface passivation and the dielectric/Si interface include Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), secondary ion mass spectroscopy (SIMS), high resolution cross-sectional transmission electron microscopy (HRXTEM), non-contact I-V, C-V and carrier lifetime measurements. Various chemical analysis techniques are also used for determining contamination sources in manufacturing. While the conventional characterization techniques have been providing useful information on the properties of the dielectric/Si interface, they cannot sufficiently provide substantive clues for many puzzling problems of Si surface cleanliness, Si surface passivation and the dielectric/Si interface. In this paper, overall quality of the Si surface and dielectric/Si interface (including cleanness, passivation and surface recombination characteristics) were characterized using room temperature photoluminescence (PL) spectroscopy. The spatial resolution of PL spectroscopy is tens of microns. To understand the depth distribution of electrically active defects/traps, at or near the Si surface and the dielectric/Si interface, different excitation wavelengths (with different probing depths) were used as the light source. Significant variations in electrically active defects, traps, and contaminants, at or near the surface, and the dielectric/Si interface were found from multiwavelength PL spectroscopic studies of Si with native oxide. Non-contact, multiwavelength PL spectroscopy was able to reveal electrically active defects and characteristics induced by the cleaning process used, which cannot be properly investigated using conventional chemical analysis and dielectric/Si interface characterization techniques.