Extreme Dewetting Resistance and Improved Visible Transmission of Ag Layers Using Sub-Nanometer Ti Capping Layers.

Area of Science:

• Materials Science
• Nanotechnology
• Thin Film Physics

Background:

• Controlling thin film dewetting is critical as deposition thicknesses decrease to the nanoscale.
• Ultra-thin silver (Ag) films are susceptible to dewetting, impacting device performance.

Purpose of the Study:

• To investigate the effect of titanium (Ti) adhesion and capping layers on the dewetting behavior of ultra-thin Ag films.
• To evaluate the impact of Ti/Ag/Ti structures on film stability and electrical properties.

Main Methods:

• Fabrication of thin film stacks (Ag with Ti layers) using magnetron sputtering.
• Analysis via scanning electron microscopy/energy dispersive X-rays, Vis/IR spectrometry, and four-point probe resistivity measurements.
• Annealing studies in air at 250 °C for 5 hours.

Main Results:

• A 0.5 nm Ti capping layer reduced the dewet area of 9 nm Ag films by an order of magnitude.
• Film resistivity remained two orders of magnitude lower in Ti-capped films compared to uncapped films after annealing.
• The Ti/Ag/Ti structure integrated into a low-emissivity window coating (with AZO) showed superior performance after annealing.

Conclusions:

• A thin Ti capping layer effectively suppresses dewetting in ultra-thin Ag films.
• The Ti/Ag/Ti structure offers improved stability and electrical performance for thin Ag films.
• This method provides a manufacturable process to enhance the longevity of devices utilizing thin Ag films.