Denuded zone formation by conventional and rapid thermal anneals

Oxygen outdiffusion by conventional annealing results in well defined denud ed zones and the dissolution of grown-in oxide precipitate nuclei in the re gion near the surface. During a rapid thermal anneal (RTA) the grown-in oxi de precipitate nuclei shrink and due to vacancy outdiffusion during cooling the subsequent growth of the precipitate nuclei is suppressed in the regio n near the surface. However, potential defects still exist in the region ne ar the surface which can grow during ramping with 1 K m(-1) starting from 5 00 degrees C. A dissolution of grown-in oxide precipitate nuclei in the reg ion near the surface seems only possible by RTA in argon/hydrogen atmospher e. The denuded zone defect density is much lower after RTA than after conve ntional annealing for oxygen outdiffusion, while the depth profile of the d efect density is less steep. The use of the above mentioned conclusions for 'ramp engineering' in device processing allows the creation of excellent d enuded zones during a device process itself without influencing the device characteristics. (C) 2000 Elsevier Science S.A. All rights reserved.