| Graphene is expected to be the next generation of interconnects technology because of its excellent electrical and thermal properties.But there are some PMMA residue on transered graphene surface,which affects the performance of devices.Therefore,in this work,graphene surface treatment was studied firstly,then a silicon-silicon low-temperature bonding technology based on graphene slurry as an intermediate layer was developed.Firstly,the single-layer graphene was prepared on Cu foil using chemical vapor deposition(CVD)method.PMMA was used as supporting layer to transfer graphene to substrate.After transfer,the graphene with PMMA residue was annealed at high temperature to remove the PMMA residue.The effect of different annealing conditions on graphene surface was studied in detail.It was found that,the concentration of PMMA residue on graphene surface is decreased gradually with annealing temperature increase.At 800 ?,the PMMA residue almost completely disappeared.Finally,the low temperature silicon-silicon bonding was realized based on graphene slurry as intermediate layer.Graphene powders,conductive carbon black and PVDF powder was mixed together,then dissolved in orgnic solvenet(NMP)to form graphene conductive slurry for bonding.The effect of different bodning conditions was studied.The electrical resistance of the intermediate layer gradually decreases and tends to be stable value with the bonding temperature got to 200 ?.Under the bonding temperature of 200 ?,bonding pressure of 2000 N and bonding time of 30 min,the bonding strength is about 5.5 MPa,which indicates that bonding strength is better.Through SEM analysis,it is found that there are no cracks,voids at bonding interface.According bongding result,the bonding machnism was explaination briefly.Therefore,it has certain feasibility for silicon-silicon low temperature bonding technology based on graphene conductive slurry,which provides new bonding technology for microelectronic packaging. |
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