Fabrication Of High Thermal Conductivity Diamond Film Upon Copper By MPCVD

Copper is an extremely important industrial materials,with the development of micro-electronics technology,the conduction of traditional heat dissipating materials cannot meet the needs of the current social industrial production,therefore the exploration of new cooling material becomes one of the keys of developing electronic device.Diamond film on copper substrate is one of the most efficient heat sink for the combination of high thermal conductivity.However,due to the poor wettability of diamond on copper substrate and the big CTE difference between diamond and copper,it is difficult to obtain diamond films using direct deposition on copper substrate.In order to obtain diamond films on copper substrate,transition layer was employed to enhance the adhesion of diamond film on the copper substrate.In this paper,diamond film was prepared on Cu substrate using microwave plasma chemical vapor deposition?MPCVD?using cuprous oxide transition layer and Cu/Cu₂O/Ni composite transition layer respectively.The quality,morphology,adhesion and thermal conductivity of diamond films were investigated.By optimizing the process of heating,controlling the temperature of heat treatment at 750?for 30 min,a dense cuprous oxide transition layer was prepared on the copper surface under the condition of N2:O2=19:1,then we prepared diamond film on the cuprous oxide transition layer by and the optimized preparation process of diamond film.The cuprous oxide transition layer was partially deoxygenized during the deposition process,which improve the interface state,when the diamond film was thin,the diamond film could be effectively combined with the copper matrix,the diamond film will crack with the deposition time prolonged.The Cu/Cu₂O/Ni composite transition layer was prepared to protect the Cu₂O oxide layer,thus preparing a thicker diamond film.The deposition parameters of the diamond films were optimized and guide the deposition of diamond film at a lower temperature.The results show that the grinding of the substrate with diamond powder on polished luns can solve the problem of damage to copper substrate,and the negative bias can effectively increase the nucleation density of diamond,optimize different parameters such as reaction pressure,microwave power and gas sources,while 2kW,5kPa,0.75%Methane concentration is the most suitable diamond deposition parameters.The oxygen atom have stronger ability to etch non diamond phase than hydrogen atom,oxygen was introducd into the gas source system,which helps to reduce grain size and optimize the quality of diamond film.By introducing Ar gas into the gas source,the deposition temperature was reduced,and the diamond film was prepared at about 600?.The Cu/Cu₂O/Ni composite transition layer can enhance the binding force between copper and diamond effectively.The high-temperature hydrogen plasma treatment can effectively inhibit the graphitization of nickel and produce copper-nickel eutectic at the interface,which enhance the bonding force.The diamond films were prepared on Cu substrate by using the Cu/Cu₂O/Ni composite transition layer,the thermal conductivity of diamond film increases by the increase of thickness and decreases by the increase of temperature.When the deposition time reached24h,the thickness of diamond film reached 16?m,the thermal conductivity of diamond film reaches 1332.6W/?m·K?at room temperature.