| Nano-thin film differs from traditional bulk materials in many physical properties,such as optics,electricity,magnetism,superconductivity,etc.These distinctive features play an important role in modern industry and are widely used,such as thin-film sensors,thin-film solar cells and flat-panel display devices.With the development of precision,intelligence,high density and high integration,the requirements for the scale of nano thin film are becoming higher and higher,which have been transferred from the previous micron level to the nanometer scale,and the requirements for its performance are increasingly demanded.The use of precision instruments and appropriate models are necessary.The object of this study is the ultra-thin silver thin film about 100 nm,With the help of the self-developed SEM-SPM joint test system,the nano-press test was carried out by using the spherical tip to the ultra-thin nano silver film,and the most real mechanical properties of thin silver film were obtained by the DMT model which considering adhesion force and the King correction model of eliminating the influence of the substrate.The results are as follows:(1)The joint test system of SEM-SPM was used to research modulus distribution of ultra sliver films with 60?90?120?180nm thickness based on the DMT model and King correction model.In order to ensure the accuracy of the experimental data,the sample preparation process and test method were taken into consideration.The combination of DMT model and King correction modelnot only eliminates the basal effect,and improves the accuracy of measurement,broaden the range of the press-in ratio.Under the same press-in ratio,the elastic modulus of ultra-thin silver film in the two test environments is independent of the film thickness and does not show the obvious size effect.When the press-in ratio is 0.1 to 0.3,the modulus under the air decreases gradually with the increase of press-in ratio,the air humidity influence the test results at this stage.When the press-in ratio is between 0.3 and 0.7,the magnitude of the different film thickness in the air remains stable and maintain at about 85 GPa.When the press in-ratio is between 0.7 and 1,the modulus is gradually reduced.To sum up,the ultra-thin film real silver nanoparticles about elastic modulus of 85 GPa,humidity for 77 RH,medium press-in ratio from 0.1 to 0.3,humidity significantly influence on the test,the result deviates from the value of the real.When press-in ratio is between 0.3 to 0.7,the effect of air humidity can be ignored.Ultra-thin nano-metal film of the test results will be affected by the serious interference of water vapor in the air,causing measurement results larger,the vacuum condition can eliminate the interference,if ultra-thin silver film mechanical properties will be tested in the air,we need to reduce the humidity of the air,and choose the press-in ratio of h/t in 0.3-0.7 range,data will be more reliable.(2)Three nano silver films with roughness(0.91,2.81,5.38 nm)were our research object,with the help of SEM-SPM test system and Bruker-AFM on the mechanical testing,it was found that: the effective value of silver elastic modulus did not significantly change with the change of roughness,so a thin silver film surface roughness has nothing to do with the elastic modulus of RMS,with the increase of roughness,the elastic modulus of amplitude increases gradually,besides,the test stability under high vacuum is higher than the result tested in the air. |
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