Strain field observed at the SiO2/Si(111) interface

The change of the strain field near the SiO2/Si(111) interface during removal of an oxide layer was investigated by X-ray diffraction under ultra high Vacuum conditions. It was observed that the width of the rocking curve for the 311 plane became narrow during thinning of the oxide layer. From a theoretical consideration, it was found that the width of rocking curve depends upon the thickness of oxide layer, even if there is no strain field at the interface. This behavior of the width is mainly due to an absorption effect of X-rays in the oxide layer. By using a resultant equation, the intrinsic curve, containing only the strain effect, was obtained by deconvoluting the absorption effect from the experimental curve. From the result, it was concluded that the strain field near the interface relaxes for thinning of the oxide layer. The strain field near the Si(111) 7x7 surface is concluded to be smaller than that of the SiO2/Si(111) interface. (C) 1999 Elsevier Science B.V. All rights reserved.