Improvement of the thermal stability of silver metallization

Abstract

The thermal stability of Ag(Al) alloy thin films on SiO2 has been investigated and compared to pure Ag thin films on SiO2 substrates. The prevention of Ag agglomeration on the SiO2 layer is a critical issue to improve the thermal stability of Ag metallization. We deposited Ag(Al) alloy thin films on SiO2 and compared them to pure Ag thin films by performing various analyses: Rutherford backscattering spectrometry, x-ray diffractometry, optical microscope, and four-point probe. Ag(Al) thin films showed good thermal stability on the SiO2 layer without any diffusion barrier and the Ag alloy thin films were stable up to 600 °C for 1 h in vacuum. No agglomeration was found during annealing for 1 h at 600 °C in vacuum. The electrical resistivity of the as-deposited Ag (3.1 at. % Al) thin film is slightly higher than that of pure Ag thin film. However, the resistivity of Ag(Al) samples annealed at high temperatures (up to 600 °C for 1 h in vacuum) remained constant due to no occurrence of agglomeration. It is confirmed in this study that the thermal stability of Ag metallization on SiO2 substrates can be enhanced by using Ag(Al) alloy thin films.