X-ray study of small dislocation loops in thermally oxidized silicon

Lattice defects in thermally oxidized silicon waters have been investigated by X-ray transmission topography. Many dotted lattice defect images were observed in the X-ray topographs. From observation of the variation in the image contrast between reflecting planes, it was found that these defects have a principal displacement along one of the <111> directions and another small displacement component perpendicular to this direction. The surfaces of the specimens were chemically etched in Sirtl solution after X-ray topography. Etch hillocks were found to be loops and half loops in the optical micrographs. One-to-one correspondence was found to exist between the etch hillocks and the X-ray images of defects. It was concluded that the defects are small dislocation loops and half loops lying on one of {111} planes and having a Burgers vector a/3 <111> normal to the plane. The shapes and the contrasts of Observed X-ray images were well explained by the displacement around a partial dislocation of edge type.