Preparation Technology And Properties Of Magnetron Sputtering SiO₂ Based LaB₆ Films

Lanthanum hexaboride(LaB₆) was widely used in electron instrument of the modern apparatus.Studies of LaB₆ films were focused on the morphology,structure and physical properties.Optical property of the LaB₆ films was studies seldomly,and it was only used as decorative materials for its special color.In order to study and utilize its special optical properties,SiO₂ was chosen as the substrate.LaB₆ films were deposited on SiO₂ substrate by magnetron sputtering.Argon pressure,substrate bias voltage,substrate temperature and sputtering power were adjusted,respectively.Style profile,AFM,SEM,HRTEM and GIXS were used to study thickness,surface morphology,structure,fracture morphology of the films and diffusion between the LaB₆ films and SiO₂ substrate.Bonding strength,hardness,elastic modulus,optical properties and electron properties were studied systematically,and influence of deposition parameters on properties of the LaB₆ films was also studied.Results of style profile showed that the influence of sputtering power on deposition rate was obvious.Deposition rate was higher than others when the deposition parameters were:sputtering power,61.6W;argon pressure,1.5Pa;bias voltage,-100V;substrate temperature,room-temperature.Maximum value of deposition rate was 19.8nm/min.When the sputtering power decreased to 17.6W, deposition rate changed to 3.22nm/min.Results of AFM showed that the LaB₆ films were smooth and compact.The influence of substrate bias voltage on surface morphology of films was obvious.There was no obvious default was found on the surface of the LaB₆ films with deposition parameters as following:sputtering power,44.0W;argon pressure,1.5Pa;bias voltage, -100V;substrate temperature,400℃.Values of average roughness of the LaB₆ films were about 2nm.Minimum value of average roughness was 1.336nm.Fracture morphologies of the films and their corresponding plane distributions were investigated by SEM.Substrate bias voltage had a deep influence on them. Diffusion between substrate and film was found.Increasing of substrate temperature was favorable to the diffusion.Results of XRD showed that most of the films were crystal.However,the obvious diffraction peaks didn't turn up in the XRD patterns of the two samples prepared under the condition of sputtering power,17.6W;argon pressure,1.5Pa;bias voltage,-100V;substrate temperature,room temperature and sputtering power,44.0W; argon pressure,1.SPa;bias voltage,-100V;substrate temperature,500℃The predominate face of all the films were(100) face,and that was different from bulk LaB₆.Results of XRD exhibited that average grain sizes were 10～30nm,and the results were consistence with the result of AFM.HRTEM was used to investigate the crystal structure of the LaB₆ film with deposition parameters as follows:sputtering power,44.0W;argon pressure,1.5Pa; bias voltage,-100V;substrate temperature,room temperature,and(100)(110)(111) face were found from the morphology.Bonding strength between the films and substrate were tested.Values of the bonding strength ranged from 110mN to 155mN.There was no discontinuity found in the loading-displacement curves,and the results indentified that elastic-plasticity was good.Values of the films ranged from 21GPa to 8GPa.UV-Vis transmitted spectrum and FT-IR absorption spectrum of the films were studied.Influence of deposition parameters on UV-Vis transmitted spectrum was not evident.There were five absorption peaks,and the wave numbers of the peaks were red shift or blue shift with the change of the deposition parameters.Resistivity of the LaB₆ films was tested.Results showed that electrical conductivity of the films was not as good as normal LaB₆.Values of resistivity ratio of LaB₆ films were from 109Ω·mm²/m to 3609Ω·mm²/m.Deposition parameters influenced electron conductivity of LaB₆ films obviously.