White light scanning interference microscopy is most commonly used for measuring single air/material surfaces. In this work, the technique has been modified for the non-destructive measurement of interface structures buried under a thick transparent layer. Test samples consisting of step structures (< 2 mum) etched in silicon and then covered by a thick layer of photo resist have been studied. The heights of the steps were measured before and after the deposition of the resist layer. Initial measurements of the profile of the buried silicon step through the transparent layer were made with a precision of 9%, the main errors in measurement being due to the degradation of the wavefront as it passes through the layer. (C) 2003 Elsevier B.V. All rights reserved.