Research On Mechanism Of Ultrasonic Fluid Driving In The Cylinder And Application Of Polishing

For the polishing method based on vibrations of liquid, this subject, which is supportedby the national natural science foundation item (No.51075195), is to study the mechanism ofultrasonic fluid driving in the cylinder and application of polishing, in the back ground ofchemically mechanical polishing and ultrasonic technology.Polishing based on Vibrations of Liquid (PVL) is using the energy which is provided byultrasonic vibrations of the vibrator. Liquid molecules and tiny polishing particles in thecylinder will impact the surface of the work piece when slurry is vibrated by the ultrasonicvibrator, so as to achieve the purpose of material removal and improving the quality of thework piece surface. In this paper, a kind of circular cylindrical piezoelectric vibrator wasdesigned and made. The vibrator dual-frequency driving method has been proposed. Thismethod is verified by theoretical analysis and experiment. Dynamic simulation of vibrator isanalyzed by ANSYS software, analyzing the vibrator’s bending vibration modessystematically. Factors affecting vibration mode and natural frequency are analyzed. Material,geometric dimensions, working modes and natural frequency of the vibrator are determined inthe end. The property of vibrator is tested. Vibration shapes are verified by testing vibrator’sresonance frequency and amplitude of circumferential and radial direction. Analyze thefactors affecting resonant frequency and amplitude, such as the height of liquid level,concentration of polshing slurry and so on. The system of PVL is designed, includingcylindrical core equipment, feedback equipment and radiating equipment. By researching thecharacteristic of liquid’s rotation speed and comparing the rotation speed in two bendingmodes, the tenth order vibration mode is determined to be the working mode in PVL finally.The experiment about polishing of silicon wafer is completed, according to PVL. SurfacemorPHology of wafers are different. The results show this method can indeed improve surfaceflatness of silicon wafer. It is more suitable for further polishing of the polished wafers withhigh surface flatness.