Research On A Staged Control Strategy For The Initiation And Propagation Of Interfacial Cracks In Non-destructive Debonding Of Ultrathin Chips

The peeling and transfer of ultra-thin chips is an indispensable common process link in the manufacture of electronic and semiconductor packaging,and it is the key to affecting performance and reliability.Actually,the traditional peeling system mainly adopts the up-suction mode.When the large-size silicon-based chip is thinned to less than 40μm,large deflection deformation is likely to occur during peeling,and it is difficult to obtain sufficient peeling force and energy release rate(ERR)at the bonding interface,crack initiation is difficult.In order to solve this problem,this paper proposes a staged strategy,which divides the peeling process into a crack initiation and a crack propagation,and adopts corresponding coupling strategies in different stages,using structural coupling and force-surface coupling to achieve optimal control of crack initiation and propagation.content include:(1)The reversible peeling characteristics of the silicon-based chip-adhesive layer were revealed by scanning electron microscope test,and the mechanical model of bonding and peeling was established,and the mechanical characteristics of peeling were analyzed.The analysis shows that the flexibility of large-sized ultra-thin chips increases,and large deflection deformation is prone to occur during peeling,which directly leads to the decrease of peeling angle,so that the deformation force of the film surface is difficult to convert into effective peeling force and energy release rate;(2)In this paper,the peeling test is carried out,and obtain the CZM characteristic unit by fitting.The fitting curve of the elastic bilinear model(Bilinear-CZM)has the highest fit with the experimental data,and the correlation coefficient is as high as 0.98.The maximum energy release rate required for peeling is G_c=10.3567N/m.The peeling process was simulated and analyzed by CZM unit,and the results showed that the changing process of peeling angle,peeling force and energy release rate were basically consistent with the analytical results;(3)Aiming at the problem of crack initiation,a coupling control method between structure and force surface is proposed.Through structural coupling,the bending moment force point during initial peeling is moved from the center of the chip to the edge attachment position,which improves the peeling angle control conditions and makes the peeling angle more easily excited.At the same time,through the cooperation of the collector down and lifter up,the rigidity of the coupling part of the chip is increased,and the overall shape of the chip is greatly suppressed.With the combination of the two,under the action of the deformation force of the film surface,the effective peeling force and the energy release rate are easy to increase,and the crack germination is accelerated;(4)A coupled acceleration control method is proposed to meet the needs of rapid crack propagation.After the crack initiation is completed,the coupling lifting is continued to realize the crack propagation.When the coupling-face below is about to hinder the crack propagation,the load loading mode is changed as follows:the face-lifting mechanism descends,and the needle at the center continues to rise.The mechanical analysis and simulation analysis show that the peeling force,peeling angle and propagation speed will be further improved when the crack initiation has been completed,and the theoretical crack propagation speed will be accelerated;(5)According to the coupling control requirements in the staged peeling,the corresponding peeling system and device are designed.The peeling process is simulated by the finite element method.The results show that theoretically,the peeling of ultra-thin and large chips can break through the chip size limit,and the theoretical peeling speed can far exceed the process requirements.In this paper,the reversible peeling characteristics of silicon-based chips were obtained by SEM analysis and an adhesive peeling model was established to analyze chip peeling,which broke through the limitation of traditional linear small deformation analysis methods.The chip peeling characteristics and peeling process were compared and analyzed by the combination of mechanical analysis and numerical simulation.Effective structural coupling and face-force coupling control methods were proposed for the crack initiation and crack propagation stages respectively,and the simulation verification was carried out.The principle and effectiveness of the new stripping process are theoretically clarified.