The interaction between high-energy ion irradiation and pre-existing damage clusters dispersed in single-crystal Si is discussed. Silicon substrates were predamaged by low-dose 150 keV Au ions. Post-irradiation by 600 keV Kr2+ ions resulted in either damage annealing or damage accumulation, depending on the substrate temperature. The transition temperature between these two different regimes is 420 K. These data are discussed and compared with the ion beam induced epitaxy and amorphization of continuous surface amorphous layers.

Polyimide films were bombarded with Ar+ at 150 keV at various doses from 5 x 10" to 2 x lo'' ions cm-'. Ion bombardment was found to produce a drastic decrease of the electrical resistivity of the polyimide from about 1OI6 to 3 x R cm, the effect being dependent on the ion dose. The chemical structure of the conductive films obtained was characterized by means of ESCA and REELS techniques. The modification of the original polymer seems to proceed at low ion doses (up to 5 x l O I 4 ions cm-') by means of the progressive elimination of the carbonyl groups and the related destruction of the imidic rings, while at high doses (from 5 x 10'' ions cm-') the carbonization of the polyimide wcurs with the production of an amorphous carbon still containing significant amount of residual N and 0 atoms.

Heavy metal gettering in silicon devices has been investigated. The best results have been obtained with POCl3 predeposition followed by annealing at moderate temperature. A model, previously developed for gold, is applied to the description of heavy metal gettering. Once inserted into a standard device process, our gettering step allows us to obtain leakage currents about 100 pA/cm2 and 1 pA/cm for diodes and storage time around 103 sec for capacitors.

A simple model for gettering of gold by phosphorus a t low concentration is proposed. This model assumes that gold is dissolved in single vacancies for intrinsic silicon, and in vacancies paired with phosphorus atoms for doped silicon. Low concentration gettering is directly compatible with MOS technology and allows leakage current in diodes to be reduced of about three orders of magnitude.Nous allons proposer un model pour decrire la capture de l'or par le phosphore. Xotre model est base sur l'hypothhse que l'or est en solution dans les vacances, e t que la capture est due A la formation d'une liaison avec un atom de phosphore. La procedure ici dhcrite pour la capture de l'or est directement compatible avec la technologie MOS.

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