Articles and Columns

Paul Dumas

LURE, centre Universitaire Paris Sud, BP 34, F-91898 Orsay Cédex, France

Mark J. Tobin

CCLRC Daresbury Laboratories, Warrington, Cheshire WA4 4AD, UK

Peter J Jenks, BSc, MRSC

the Jenks Partnership, Newhaven House, Junction Road, Alderbury, Salisbury,Wiltshire SP5 3AZ, UK. E-mail: [email protected]

Tony Davies,^a Peter Lampen,^b Maren Fiege,^c Thorsten Richter^c and Thorsten Fröhlich^c

^aExternal Professor, University of Glamorgan, UK. c/o Creon Lab Control AG, Europaallee 27-29 50226 Frechen, Germany
^bISAS, institute for Spectrochemistry and Applied Spectroscopy, Dortmund, Germany
^cCreon Lab Control AG, Europaallee 27-29 50226 Frechen, Germany

Peter J. Jenks

the Jenks Partnership, Newhaven House, Junction Road, Alderbury,Wiltshire SP5 3AZ, UK. E-mail: [email protected]

T. Wirtz and H.-N. Migeon

Laboratoire d’Analyse des Matériaux, Centre de Recherche Public - Gabriel Lippmann, 162A, av. de la Faïencerie, L-1511 Luxembourg, [email protected]

The International Spectroscopic Database (IS-DB) went live on 19 May 2003. Following over seven years fighting for funding and receiving the EU EuroSpec grant1 in 2002 the team are pleased to announce that the first version of the international digital archive for spectroscopic data was switched on for data deposition in May.

Luisa Mannina,^a,b Anatoli P. Sobolev^b and Annalaura Segre^b

^aUniversity of Molise, Faculty of Agriculture, 86100 Campobasso, Italy
^bInstitute of Chemical Methodologies, CNR, 00016 Monterotondo Staz., Rome, Italy

Moore’s law* dictates microelectronics researchers to make integrated circuit (IC) devices smaller and to put them as close to each other as possible on a chip. This results in a better performance and a larger functionality of the chips. However, these devices also require a good electrical isolation from each other. This is in general done by the formation of a thick local oxide in the “field region” between the devices. In 1970, researchers from Philips¹ invented the so-called LOCOS (LOCal Oxidation of Silicon) technique to achieve this isolation. Using a Si₃N₄ mask, the silicon is thermally oxidised in the nitride-free field regions. Figure 1 (left) shows a typical LOCOS structure. Although LOCOS seemed a perfect solution at that time, it came with a lot of problems, many of them related to mechanical stresses. Thermal oxidation of Si to SiO₂ occurs together with a 125% volume expansion. As a result, the oxide grown in the field region, called the “field oxide,” exerts large forces on the surrounding silicon. Another major drawback of this technique is the so-called “bird’s beak,” caused by the lateral growth of the oxide under the nitride mask. This bird’s beak not only affects the intended device length, it also introduces large local mechanical stresses in the silicon, because of volume expansion, and it also deforms the nitride film. These stresses often resulted in the generation of dislocations in the silicon, which are quite harmful for the devices.

Alan Street

Technical Director, Oxford Instruments Superconductivity

Peter J. Jenks

the Jenks Partnership, Newhaven House, Junction Road, Alderbury,Wiltshire SP5 3AZ, UK. E-mail: [email protected]