Characterization of defects in Si films on SiO2 layer

Abstract

SOI (Silicon-on-lnsulator) offers many advantages for integrated circuits including faster switching speed, high packing density, radiation resistance, and latch-up free. It can also be used in the integration of high voltage devices and/ or sensors. Defect-free Si films with a small interior stress are required for the application mentioned above. Therefore a heat-sink and a valley entrainment structure (Fig. 1) were made in order to confine defects to predetermined locations and to leave the other areas of the recrystallized silicon film defect-free.Using a cross—section specimen electron microscopy we have observed some kinds of defects in unseeded rapid zone-melting-recrystallized (RZMR) Si films which were prepared with a RF-induced graphite strip heater system. The scanning speed of the graphite strip heater is 11 mm / sec. Fig.2 shows a cross-section image of a valley structure specimen. Not any defect has been found in region A, which means that about 10μm wide defect-free Si film can be obtained by the process. Region C is an unpatterned normal area with a uniform thickness.The subgrain boundaries (SGBs) with an interval less than 6μm were observed in the region C.