Research On The Formation Mechanism Of SiO₂ Insulation Thin Film For Metal Substrate Sensor

In a large number of insulating materials,amorphous SiO₂ thin film has good stability and insulation,low thermal expansion coefficient,compact surface and wear resistance,good adhesion force.SiO₂ films have been widely used in the fields of microelectronics,semiconductors,integrated circuits,thin film sensors and so on.In this paper,the direct current?DC?pulse magnetron sputtering method was used to prepare the SiO₂ film at room temperature.The step profiler,atomic force microscope?AFM?,ZC-90D insulation resistance measurement system,X-ray diffractometer?XRD?,and transmission electron microscope?TEM?were carried out to all samples.By this technigues,thickness of the film,substrate surface roughness,insulation resistance,crystal structure,microstructure of SiO₂ film were measurement.Through the above characterization method,the insulation properties of SiO₂ films prepared by different process methods are studied and the mechanism of defect formation in SiO₂ films was systematically studied.The results of the study show that:1.For SiO₂ films deposited for 1 hour on different rough surface Si substrates,and the thickness is about 840 nm.Its resistance value is less than 106 ?,which can not play the insulation effect.For SiO₂ films deposited at different time on the same substrate.When the deposition time is 3 hours and the film thickness is 2.6 ?m,the resistivity of the films is 3.3×106 ? m,which can play an excellent role in insulation.The transmission electron microscope?TEM?results show that the resistivity is seriously reduced by the linear structure of the lower local atomic density of the SiO₂ film.2.The sub deposition of different time intervals is realized by LabView automatic control of the switch of the pulse source.With the increase of deposition times,the resistivity of SiO₂ film is gradually increased,when each 4 min interval time of SiO₂ thin film preparation,the resistivity reaches the maximum value of 7.22x107 ?·m.From transmission electron microscopy results show that the SiO₂ films prepared by different time intervals can have obvious stratification,it is because of the emergence of layered film,the linear structure of the lower local atomic density of the thin film is dislocation distribution,the insulation performance of the film is improved to a certain degree.3.The SiO₂ film was deposited by the direct current pulsed magnetron sputtering technology,which the reciprocating motion was carried out onto the substrate.Without reciprocating motion,the resistivity of SiO₂ film was only about 1.98×107 ?·m.With 500 circles reciprocating motion,the resistivity increased to 4.93 ×109 ?·m.Transmission electron microscopy results revealed that the straight line structure with lower local atomic density passed over SiO₂ film,which deteriorated the resistivity seriously.The reciprocating motion of substrate could destroy above straight line structure to pass over SiO₂ film,which kept SiO₂ film with resistivity at 109 ?·m.4.Application of the prepared SiO₂ insulating film to NiCr/NiSi thin film thermocouple and ITO thin film strain gauge.After testing,the Seebeck coefficient of NiCr/NiSi thin film thermocouple has good linearity of 41.4 ?V/K.The sensitivity coefficient of the ITO thin film strain gauge is-4.238.It is prepared SiO₂ films by different process methods to meet the insulation layer of the film sensor on the metal substrate.