Research On Process Of Copper Thin Film Sprayed By Atmospheric Pressure Plasma

The current major methods for preparing metal thin films include physical vapor deposition（PVD）,chemical vapor deposition（CVD）,electroplating,and electroless plating.For conventional PVD and CVD,precursors are often solid or gaseous and have fewer species;the reducing gas used is often hydrogen,but hydrogen is flammable and explosive;in the preparation of metal films,the reaction temperature is high,and the matrix is easily damaged.The type of substrate,and the film often need annealing treatment;deposition needs to be carried out in a vacuum environment,limiting the size of the substrate.For electroplating or electroless plating,the preparation of metal thin films often produces a large amount of chemical waste liquid,and the environment is unfriendly.The technique of atmospheric pressure cold plasma spraying can solve the deficiencies of the above thin film preparation techniques.However,this technique has rarely been reported in the preparation of metallic thin films.In this paper,the preparation of copper thin film as a research object,to explore a normal cold plasma spraying technology to prepare Cu thin film.Using NH₃ as a source gas,mixing with N₂ in a certain ratio,using argon gas as a shielding gas and Cu（NO₃）₂ as a copper source,the Cu（NO₃）₂ solution is atomized and passed downstream of the plasma jet,and a plasma is used.The spray gun scans the copper film.The influences of different process parameters on the macroscopic morphology,micro-morphology,film composition and film resistivity of the film samples were systematically studied.The formation mechanism of atmospheric pressure cold plasma sprayed copper films was also analyzed.The main conclusions are as follow:（1）When the scanning rate of the gun is gradually increased from 7 cm/s to 19 cm/s,the chemical state of copper in the deposited thin film sample gradually transitions from Cu²⁺to Cu⁺and finally changes to Cu,and the grain size on the surface of the film gradually decreases.The resistivity is also significantly reduced.When the scanning rate of the gun is16 cm/s and 19 cm/s,the copper element in the film is zero-valent.The grain on the surface of the film is closely arranged and the resistivity of the film is small.Therefore,the scanning rate parameter of the spray gun plays a dominant role in the process of spraying the copper thin film.（2）When the spraying power was gradually increased from 300 W to 600 W,the oxide content of copper in the film decreased,and then increased.When the spraying power was400 W,the content of copper oxide in the film was the lowest.At 300 W,the uniformity of grain size on the surface of the film is poor,and the resistivity of the film is the largest;at 400W,the grain size on the surface of the film is the smallest,uniform and tightly packed,and the resistivity of the film is the smallest;when the spraying power is 500 W and 600 W,the film thickness is As the oxide content increases,the grain size of the film increases,and the resistivity of the film also increases.（3）When the concentration of copper nitrate was gradually increased from 60 g/L to 140g/L,the content of cuprous oxide in the film gradually decreased,the crystal grains on the surface of the film were tightly packed,the film was denser,and the resistivity of the film was gradually smaller;When the concentration of copper nitrate was gradually increased from 140g/L to 220 g/L,the content of cuprous oxide in the film did not increase,but the grain size on the surface of the film increased,the density of the film decreased,and the resistivity of the film slightly increased.