THERMAL-STABILITY OF UNIFORM SILVER CLUSTERS PREPARED ON OXIDIZED SILICON AND ALUMINUM SURFACES BY ELECTRON-BEAM LITHOGRAPHY IN OXIDIZING AND REDUCING AMBIENTS

100 and 750 nm silver nanoclusters are fabricated on oxidized silicon and aluminum surfaces by electron beam lithography. Silver nanocluster s are characterized by atomic force microscopy, scanning electron micr oscopy, scanning Auger electron microscopy and high-resolution optical microscopy. The ordered structure of silver nanoclusters facilitates a thermal stability study in both reducing and oxidizing conditions. I n reducing conditions, silver clusters are stable on the surfaces up t o similar to 700 degrees C before evaporation. The thermal stability o f silver clusters is significantly lower in oxidizing conditions. In t he presence of oxygen, the silver cluster surface is oxidized and roug hened < 300 degrees C. Heating above 350-400 degrees C in oxidizing co nditions induces a migration of silver clusters. Micron-size and submi cron-size amorphous silver clusters are formed, which spread over the oxide support. On oxidized silicon substrate, annealing treatment at 3 00 degrees C induces silver silicate formation or spreading of oxidize d silicon support onto the silver clusters, causing a buildup of silic on on the silver cluster surface. On the oxidized aluminum surface, by contrast, no spreading or reaction of the oxide substrate with the si lver clusters was detected.