Development of a novel tool for semiconductor process control

A collaborative project between the Surrey Ion Beam Centre and the positron beam group at the University of Bath is developing a bench-top positron to ol suitable for use in the semiconductor industry. The technique's non-dest ructive nature, coupled with its high sensitivity to defects, makes it a po tentially ideal method for detecting process problems at an early stage. Me asurements on the existing laboratory-based system have shown, for example, a high sensitivity to variations in parameters such as temperature in the growth of epitaxial layers. An instrument suitable for use in the fabricati on environment is described, together with diagnostic studies of PECVD-depo sited SiN layers. of thicknesses in the range 21-133 nm, performed in conju nction with ellipsometric and RES measurement. The technique is sensitive t o the atomic composition of the SiN epilayers and, in conjunction with elli psometry, is able to measure the density of the layers and to quantify the densification on annealing at 900 degreesC. (C) 2001 Elsevier Science B.V. All rights reserved.