MICROPIPES AND VOIDS AT BETA-SIC SI(100) INTERFACES - AN ELECTRON-MICROSCOPY STUDY/

The microstructure of beta-SiC/Si(100) interfaces generated by carboni zation and subsequent growth in a chemical vapor deposition (CVD) reac tor was investigated by transmission electron microscopy (TEM). Differ ently prepared cross section and planar specimens allowed a detailed c haracterization of interface defects. Besides pyramidal voids, which w ere frequently reported to appear at SiC/Si interfaces within the subs trate, recently discovered micropipes are of special interest. Both ki nds of defects form by outdiffusion of silicon during the carbonizatio n process. In contrast to voids. which initially remain empty, micropi pes develop by simultaneous ingrowth of SiC. The area densities of mic ropipes were found to be orders of magnitude higher than those of void s. Micropipe formation may be due to a high density of SiC nuclei pree xisting on the substrate surfaces after pretreatments. The simultaneou s development of voids and micropipes is discussed on the basis of res ults obtained from a short-time carbonization experiment.