Effect of Interstitial Oxygen on Formation of Amorphous SiOx Layerin Directly Bonded Czochralski Silicon Wafers

Abstract
We have investigated the effect of interstitial oxygen in CZ silicon wafers on the formation of the amorphous SiO x layer (x=0.2-0.3 after annealing at 1100°C for 2 h) at the interface in directly bonded silicon wafers using high-resolution transmission electron microscopy (HR-TEM) and energy dispersive X-ray (EDX). As the annealing time became longer, the thickness and the oxygen concentration in this layer increased, depending on the concentration of interstitial oxygen in wafers. These changes are caused by the diffusion of oxygen atoms from the bulk toward the bonded interface. However, they must not play such an important role in the initial stage of the formation of this layer because the layer existed discontinuously and was not affected by rotational misorientation or the microroughness.

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