Development And Application Of A Vacuum Sample Transfer System And An In-situ Electrical Testing Multi-Probes Module

According to statistics,approximately one-third of the world’s primary energy consumption is attributed to friction.If the superlubricity（friction coefficient equals 0.001 or below）can be widely used,it will greatly reduce the energy dissipation during the friction process,save lots of energy and bring significant economic benefits.In order to detect the energy dissipation path and reveal the energy dissipation mechanism,multiple instruments need to be used to detect the energy dissipation at the same time.As an important instrument necessary for the study of nanotribology,the further development of scanning probe microscopy（SPM）would continuously promote nanotribology,superlubricity and other fields.Therefore,relying on the National Natural Science Foundation of China（51975488）,the development and application of a vacuum sample transfer system and an in-situ electrical testing multi-probes module for the multi-probes system was completed.As one of the six key sub-systems of the world’s first high-resolution in-situ real-time energy dissipation detection system in tribo-process（EDDS）,the multi-probes system is conducive to the control of micro/nano friction process and the detection of energy dissipation and provides an in-situ detection means to reveal the superlubricity mechanism and energy dissipation mechanism in the friction process.The main research contents of this thesis can be summarized as follows:（1）Unlike the existing sample transmission technology connecting the cavity through a vacuum pipe,a sample box would be used to transmit the sample between the ultra-high vacuum rotating cavity and the test cavity,which would avoid the pollution and interference between instruments,realize the separate transmission of samples,avoid overload and inadvertent grounding,and make no sliding friction to protect the sample.The ultra-high vacuum rotating cavity could realize the ultra-high vacuum environment(5.2×10^-8 mbar).The multi-probes cavity could realize a high vacuum environment(3.6×10^-6 mbar)and control different kinds（air,N₂,O₂,Ar,etc.）and humidity（0～90%RH）gases.The plate vacuum sample transmission device realizes the transmission of the standard sample holder and high vacuum sealing(3.9×10^-6 mbar).The comb-type vacuum sample transmission device realizes the independent transmission of samples of various sizes without a sample holder,with a small overall transmission weight,no sliding friction,and high vacuum sealing(2.9×10^-6 mbar).（2）Based on the previous research of our group,by coupling electrical test,the development of combined probe switching devices was complete,which could realize the high precision（3μrad）of multiple probes by numerical control,which realized the in-situ electrical test and tribological test of the multi-mode probes.Unlike the existing multi-probes testing technology of scanning probe microscopy,the contact combined probe switching device would be more suitable for the multi-probes system,and the structure would be simple,reliable and easy to process.Moreover,the contact combined probe switching device could realize high vacuum sealing(2.1×10^-6 mbar).The multi-mode combined probe switching device would drive the in-situ switching of up to four probes,including one multi-mode probe and support the switching of contact/tapping mode AFM,FFM,SKPM,EFM,C-AFM,MFM and PRM in high vacuum,air and controllable gas atmosphere to realize stable and reliable high-resolution in-situ testing.Moreover,it can realize high vacuum sealing(2.2×10^-6 mbar).（3）The multi-probe system was tested in multi-environment and multi-mode and applied to the study of nanoscale material removal of tantalum,a commonly used barrier material in integrated circuits.The quantitative contribution of mechanical wear to electrochemical corrosion in atomic-scale removal was clarified.The surface of the tantalum wafer went through the processes of desorption,oxide layer wear and substrate material wear,which would eventually lead to the gradual increase of the surface potential（～15.59 mV）and change the electrode potential difference of micro galvanic corrosion,thus affecting the micro galvanic corrosion process of the sample under the synergistic action of chemical and mechanical.Under the synergistic action of chemical machinery,the friction dissipation energy(E_dis)has a linear relationship with the material removal energy(E_remo):E_remo=（0.37943±0.02807）·k_xE_dis,where the coefficient k_x represents the average number of Ta-O bonds to be disconnected for each Ta₂O₅ molecule removed.The work is helping to promote the study of the energy dissipation mechanism under chemical mechanical synergy.