Study On Mechanism And Sectional Damage Of Monocrystalline Silicon Byultrasonic Assisted Cutting

At present,monocrystalline silicon iswidely used in the field of integrated chips and photovoltaic power generationas the semiconductor materials.The cutting process of monocrystalline silicon is the last process before the packaging of components in production process of semiconductor components.The damage caused by the cutting will be directly wrapped on the workpiece.It directly affects the quality of workpiece.Andultrasonic machining is beneficial to reduce the damage of brittle materialsas a special machining method.It has a unique processing advantage for brittle materials.The effect of ultrasonic vibration on cutting is studied systematically.The influence of ultrasonic vibration on the damage of the monocrystallinesilicon is studied in order to provide more experimental and theoretical basis for ultrasonic cutting monocrystalline silicon technology.The kinematics model of single abrasive particle in the cutting process is established,and the movement of the abrasive particles in cutting zone is analyzed.The equations of motion trajectory,velocity and acceleration of abrasive particles are listed.The similarities and differences of the trajectories of single and multiple grainsbetween ultrasonic machining and conventional machining are discussed.The cutting force,chipping size and surface morphology of the cutting area are analyzed.The ultrasonic cutting force is less than ordinary cutting force.At the same time,the chipping size is also smallerbecause of its small ultrasonic cutting force.The sectionformation model of ultrasonic assisted cutting of monocrystalline silicon is established.The effect of ultrasonic vibration on the formation of cutting section is analyzed.The surface roughness produced by ultrasonic&normal cutting is analyzed.It is found that the sectional roughness of ultrasonic cutting is smaller than that of normal cutting.The mechanism formation of the cutting section damage is analyzed.The damage modelof damage model is established is established.And,the depth of the damage layer is measured by two methods: chemical etching and section polishing.The experimental results show that the cross-section damage caused by ultrasonic cutting is smaller than that of normal cutting.Besides,the damage depth measured by the chemical etching method is greater than the damage depth measured by the section polishing methodbecause of the chemical corrosion method is more sensitive to the residual stress and dislocation damage.Finally,theoretical calculation model for estimating the depth of the damage by cutting surface roughness is established by using the indentation fracture mechanics.