Ag Thin Film Dewetting Prevention by Ion Implantation

Abstract

antidewetting upon SiO 2 /Si substrate by Al doping, yet neither of them provided a theoretical explanation to detail the mechanism. [26][27][28] Despite the contribu tion that the aforementioned approach made to increase thin film stability, novel strategies for film dewetting prevention are very much an open research ques tion. Here we introduce a novel antidewet ting strategy through ion implantation. Si and In atoms are implanted into Ag thin film to alter its wettability during thermal annealing. Si is primarily researched here because Ag-Si interdiffusion plays a crit ical role in modern Si-Ag based electro nics industry and a systematic research on Sidoped Ag thin films may provide essen tial reference for its further development. In has achieved antidewetting purpose according to Gu el al. thus is used here as additional support to our antidewet ting strategy. [27,28] Other elements such as Al, Cu, Pt that succeeded in Ag thin film dewetting prevention and Na that failed in this purpose are not discussed here due to the limited content. [26][27][28][29][30][31][32] Sapphire is widely used as substrate for epitaxial growth of IIInitride, LEDs, and microelectronic applications due to its wide optical bandgap, superior chemical and mechanical robustness. Thus, it is selected as the substrate in our research. Furthermore studying on Ag nanostructure upon sapphire could be helpful to develop novel optical or plasmonic applications. [14,[33][34][35][36] It is found that a doping dose of 10 14 cm −2 Si or In atoms are sufficient to prevent Ag film from fracture at 530 °C. A novel grain growth model is established here and, combined with our thermodynamic simulation, shows that the Ag dewetting is pre vented due to the substantially decreased film grain size attrib uted to the dopantinduced solute drag.100 nm Ag films are prepared by sputtering (Torr Inter national, Inc.) at room temperature and at a base pressure of ≈5 × 10 −6 Torr on polished single crystal sapphire substrates. Figure 1a,b shows the optical microscopy images of a) as deposited Ag film and b) Sidoped Ag film before (top) and after (bottom) annealing, respectively. No evident distinctions can be observed from either sample before heat treatment, there is simply the high reflectivity image, which is generally feature less in optical microscopy. However, upon annealing at 530 °C for 30 min in an at a vacuum of 10 −5 Torr, which is a common temperature window in the semiconductor industry, the non doped Ag film appears to have obvious microscale islanding and exposes the sapphire subsurface while the Sidoped sample remains intact. Atomic force microscopy (AFM) images with higher magnification are shown in Figure 1c-e which Ion implantation is applied here to prevent metallic silver (Ag) thin films from dewetting on a sapphire substrate during annealing. In these experiments, silicon (Si) and indium (In) atoms are implanted into Ag thin films grown directly on sapphire, which are then annealed for different time periods to introduce film dewetting. I...

Epitaxial Silver Films Morphology and Optical Properties Evolution over Two Years

“…Some works stress the role of the H 2 O layer in the chemical reaction of the degradation process leading to the dissociation of silver atoms [28]. Dewetting of silver layers was also considered in some published papers [27,[29][30][31]. These studies demonstrate that silver degradation can be promoted by surface tension forces induced in silver thin films during deposition.…”