The Investigation on Au Nano-particles on Si Wafer after Annealing at Different Temperatures

Abstract

In this study, in order to investigate the morphology change of Au nano-particles/island film with the sputtering time and annealing time, Au nano-particles/island films were sputtered on the (100) silicon wafers by radio-frequency magnetron sputtering. Before deposition, the background vacuum of deposition chamber was a base pressure of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-5</sup> mbar. During sputtering, Ar pressure is changed to 2.5 00 × B4; 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> mbar. Au islands were sputtered on Si wafer with different time, which are 5 seconds, 10 seconds, 20 seconds, 30 seconds, and 60 seconds, respectively. After sputtering, the samples were annealed at 100oC, 200°C and 400°C for 1h with the heating and cooling rate of approximately 10°C/min., respectively. Scanning electron microscope (SEM; LEO 1530) was used to examine the microstructures and morphology of the films. The results showed that the morphology of Au nano-particles/island films were different with the increasing sputtering time. Au particles experienced a dramatic change on the Si wafer surface, when sputtering time changed from 5sec. to 60 sec. In order to decrease the surface free energy, Au particles diffused and agglomerated with the increasing annealing temperature. With the sputtering time increasing, the size of Au nano-particles changed large. With the annealing temperature increasing, the Au atoms diffused and agglomerated. Au nano-particles changed island films or unregular strips.