An investigation was made of the effects of the step-wise heat treatment of [100] Czochralski and float-zone material. It was found that heat treatment of a Si substrate could result in the precipitation of interstitial O. The precipitated O produced elastic stresses, in the crystal, which could be relieved by the generation of defects. The evolution of these defects considerably accelerated the lateral etching rate. In samples without heat treatment, the anisotropy took values of 110 and 70 for float-zone and Czochralski samples, respectively. With increasing temperature and processing time, the anisotropy decreased to 30 in float-zone samples and to 15 in Czochralski samples. At the same time, the surface quality of (100) and (111) planes decreased with increasing temperature.

The Effects of Thermal Treatment on the Anisotropic Etching Behavior of Cz- and FZ-Silicon. A.Hein, S.Finkbeiner, J.Marek, E.Obermeier: Sensors and Actuators A, 2000, 86[1-2], 86-90