Structural Study of Thin Copper and Brass Films Deposited on a Polyimide Substrate by PLD

Thin films of copper and brass were deposited on polyimide substrate by using pulsed laser deposition (PLD) method. The target materials selected for this study were Copper Ml and Brass LS59-1. The structures of these materials were analyzed using a metallographic microscope 1350 (ADF, China), and their chemical compositions were examined using an energy dispersive microanalysis (Bruker) to control their chemical purity. Film deposition was made by excimer <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{KrF}$</tex> laser (wavelength λ = 248 nm, pulse duration <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\tau=20$</tex> ns, energy density <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{W}=5\mathrm{J}/\text{cm}^{2})$</tex>. The average value of the pressure in the working chamber during the experiment was <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{P}=10^{-6}$</tex> Torr. Obtained metal films were studied by using TM4000 Plus scanning electron microscope (Hitachi, Japan). Investigated structure contained imperfections, such as droplects and pores. The reasons which can help to understand and explain their occurrence are given. A small literature review was made to underline the ways of droplet reduction.