It is clarified that a new type of singularity is formed on Si wafer surface by the Standard Cleaning 1 (SC1) of the RCA cleaning process. Such singularities are perceived by laser particle counters as small particles on wafers. It is shown that the singularities correspond to small shallow pits caused by the etching effect of the SC1 cleaning solution. The origin of the pits is presumed to be some kind of defect in the melt-grown crystals.

It was recently revealed that singularities (crystal-originated “particles”) formed on Si wafers after SC1 cleaning originate from some defects in crystals and were perceived by laser particle counters. In this paper, the size distribution of crystal-originated “particles” is examined in detail by means of repeated SC1 cleanings. It is shown that, as the crystal pulling rate becomes faster, the size distribution of crystal-originated “particles” shifts toward smaller size, and the total number of origins of crystal-originated “particles” increases.

A total reflection X-ray fluorescence (TRXRF) technique has been recently used to analyze metal contaminations on Si wafers. In this work, microdrop-contaminated Si wafers are used to make the calibration curves. Metal impurities in these wafers are shown to be condensed in a very small area near the center of the dropped area. To make the calibration curve, a relationship is derived between the intensity of the characteristic X-ray from metal impurities in the condensed area and that from the impurities uniformly distributed over the wafer surface. On the basis of this relationship, calibration curves for Fe, Ni, Cu and Zn are obtained.

Thin silicon-on-insulator (SOI) layers of 0.5–2 µ m thickness are characterized by the microwave photoconductivity decay (µ-PCD) method with an N2 laser as the excitation source. The penetration depth of the N2 laser light is less than 0.1 µ m, and thus the excess carriers are excited only in the SOI layers. The measured recombination lifetime is sensitive to SOI thickness and interface properties, and thus the µ-PCD method can be used for characterization of the interface and observation of thickness variation. The surface (interface) recombination is considered as the dominant recombination mechanism.