Micro-Raman characterization of crystallinity of laser-recrystallized silicon films on SiO2 insulators

Abstract

The crystallinity of laser-recrystallized Si films on insulators ͑SOI films͒ was characterized by micro-Raman imaging. A small-angle bevel made by angle lapping of the SOI film was used to probe the structure at different depths. The Raman signals that varied with the position along the tilt show that interference of both the incident and scattered light induced in the angle-lapped specimens results in periodic enhancements in the intensity as a function of film thickness. An analysis of the fringe patterns in the Raman images provides us with depth profiles of strain and structural disorders with a high depth resolution on a scale of a few tens of nanometers. When moving away from the interface between the silicon film and the insulator, the peak frequency of the polycrystalline silicon band shifts to the lower frequency side and the band width becomes smaller. The depth profile of the Raman feature shows that the defect density is high in the region near the interface of Si and SiO 2 , and that the stress increases toward the top surface of the silicon film. Moreover, a partial relaxation of the stress occurs near the interface region due to the generation of a high density of defects.

Interference‐enhanced Raman scattering in SiO2/Si structures related to reflectance

“…Reflections are not more specular for wider incident angles, which introduce considerable deviations from the prediction as is obvious from Figure b,c (obtained with 80 g LWD and 100 g objectives with NA = 0.75 and 0.9). Similar effects may be observed in an experiment with wedge‐shaped layers or under tilting…”

Hydrogenation Effects on Chemical Activity of Defects in Excimer-Laser-Annealed Polycrystalline Silicon Thin Films

“…7) For laser-crystallized Si films on an insulator, it was shown that OPM intensity periodically varies with film thickness. 8) Referring to those results, the intensity of a poly-Si film on a SiO 2 underlayer is expected to be maximum at a thickness of 60 nm and minimum at 30 nm followed by an increase and finally a decrease. Because the original thickness of the present poly-Si film is 50 nm, the variation in intensity with etching time shown in Fig.…”

Characterization of Defects and Stress in Polycrystalline Silicon Thin Films on Glass Substrates by Raman Microscopy

“…In the case of thin films, their thickness impacts the spectral intensity. The variation of the intensity with thickness has been investigated by calculations and experiments for SOS, and the interference of the incident light and scattering light in thin films were taken into account [23]. For ELC poly-Si film on SiO 2 -coated glass, the variation of the OPM intensity with film thickness was calculated as shown in Figure 9.…”