Effect Of Annealing And Buffer Layeron Properties Of Carbon-rich SiC Films

SiC film is functional material with high thermal conductivity,high hardness and good chemical stability.It is widely used in nuclear protection,microelectronics and device protection.However with the continuous development of modern technology the requirements for material properties are getting higher and higher.Traditional SiC films have also exposed a variety of problems in applications.For example the adhesion between the films and substrate is poor because the properties of the SiC films and the base material are very different.Sometimes which even can make the films fall off.The SiC films may also undergo brittle fracture,resulting in films failure.The existence of these problems restricts the further application of SiC films.In order to solve the current problems and improve the performance of SiC films we attempt to prepare carbon-rich SiC films by doping carbon into SiC films.The effects of annealing temperature and buffer layers thickness on the properties of carbon-rich SiC films were studied.The results are as follows.(1)In Chapter 3,we prepared carbon-rich SiC films by using DC magnetron sputtering technology on the substrate deposited with a SiAlON buffer layers.The effect of annealing temperature on the properties of SiC films is studied.During the experiment the annealing temperature range was set to 400℃～700℃.The study found that the annealing temperature can not make the SiC films crystallize.But it can significantly change the bonding state of the free C element in the SiC films.With the gradual increase of the annealing temperature,the sp3 bond in the SiC films gradually increases under the action of Si element.When the annealing temperature exceeds 550℃,the SiC films will gradually graphitize.SEM test results show that a certain annealing temperature can improve the surface quality of SiC films.However when the annealing temperature is too high,the graphitization of the films will also cause the surface quality to gradually deteriorate.Annealing can change the bonding state of C element in the SiC films and release the internal stress in the film which makes the hardness and adhesion of the SiC films increase.When the annealing temperature is 550℃,the hardness of the SiC film reaches the maximum value,which is 25.02GPa.When the annealing temperature is 500℃,the adhension of the SiC film reaches the maximum value,which is 45.22N.The friction coefficients of the SiC films prepared in this experiment are all below 0.19.And when the annealing temperature is 550℃the friction coefficient of the SiC film reaches a minimum value of 0.083.(2)We deposited the SiOC buffer layers and carbon-rich SiC films on the SiAlON buffer layers by using magnetron sputtering technology.The influence of the SiOC buffer layers thickness on the properties of SiC film was studied.XRD results show that the change in the thickness of the SiOC buffer layers does not affect the crystalline state of the SiC film.SEM results show that the introduction of a certain thickness of SiOC buffer layer can effectively reduce the stress in SiC film and improve the surface quality of SiC films.However when the thickness of the buffer layer is 300 nm the surface quality of the SiC film will deteriorate.The mechanical property test results show that when the thickness of the SiOC buffer layer is 100nm the hardness of the SiC film reaches a maximum value of 22.12GPa.When the thickness of the SiOC buffer layer is 200nm the adhesion of the SiC film reaches a maximum of 40.72N.(3)The different thicknesses of AIN buffer layers were prepared by radio frequency magnetron sputtering technology on SiAlON films.Subsequently DC magnetron sputtering technique was used to deposit carbon-rich SiC films of the same thickness on AIN buffer layers.The effect of the thickness of AIN buffer layers on the properties of SiC thin films has been studied.XRD results show that the SiC films prepared in this experiment are exhibit amorphous structure.Through the comparison of SEM images,we can find that AIN buffer layers can provide a good template for the growth of SiC films.This makes the SiC films surface particles gradually become uniform in size and improves the surface quality and density of the SiC films.The results of mechanical tests show that the introduction of the AIN buffer layers can fully release the stress of the SiC films which improves its hardness and adhension.When the thickness of the AIN buffer layer is 60nm,the hardness of the SiC film reaches a maximum,which is 22.68GPa.When the thickness of the AIN buffer layer is 90nm,the adhension of the SiC film reaches the maximum value,which is 42.8 1N.In addition in the friction coefficient test of the SiC films we found that when the thickness of the AIN buffer layer is 60 nm the friction coefficient of the SiC film is only 0.080.