Basic Research On Hybrid Technology Of Ultrasonic Elliptic Vibration Assisted Chemical-Mechanical Polishing A Silicon Wafer

On the basis of analyzing the present situation of chemical mechanical polishing (CMP) and ultrasonic machining (USM) at home and aboard, according to technical status and existing problems of traditional CMP, especially for the diameter of silicon wafer increasing, constantly, the surface quality and efficiency of silicon wafer polishing are becoming an urgent problem to be solved and improved, so the research subject of ultrasonic elliptic vibration chemical-mechanical hybrid polishing(UEVCMHP) new technique is proposed. The compound polishing technique is novel processing technique that ultrasonic processing and chemical mechanical polishing are integrated. The ultrasonic elliptic vibration polishing technique was applied to polishing tool based on the traditional CMP technique. For utilization of the ultrasonic elliptic vibration from the polishing tool, the performance of polishing slurry is improved in the process of CMP, and the object is implemented to improve polishing result. By means of theoretical analysis combined with experimental research, the processing mechanism and technology of integrate polishing was studied systematically and thoroughly, and the main contents and innovations were included:1. The principle of the ultrasonic elliptic vibration polishing was introduced, and a theory model for designing the polishing tool was established. A polishing tool used in silicon wafer top surface and edge treatment was studied, then frequency-impedance and elliptical motion characteristics of polishing tools were tested.2. The experimental equipment of integrate polishing was developed based on traditional CMP, in order to realize different vibrations, such as ultrasonic longitudinal vibration, ultrasonic shear vibration and ultrasonic elliptic vibration.3. Base on CMP and USM, the mechanism of integrate polishing was analyzed systematically. According to the contact mechanics theory, the contact model between the wafer and the pad was built. On the basis of systematical studies for the influence of each main input parameters in machine polishing to quality characteristics of process surface, a simple and practical theoretical model for the material removing of integrate polishing was established. The fundamental researches of material remove mechanism and processing surface quality was developed based on three integrate polishing methods including ultrasonic longitudinal vibration, ultrasonic shear vibration and ultrasonic elliptic vibration. The results showed that the ultrasonic elliptic vibration of polishing tools was more advantageous to improve the effect of silicon chip synthesis polishing.4. In the situation of non-destructive work piece surface, a simple, practical and fast measurement method for micro-remove rate from the hard-brittle materials was studied.5. The experiments were studied on input process parameters, i.e., ultrasonic performance of polishing tool, polishing pressure, slurry supplying, wafer velocity at polishing point, polishing pad, which acted on the surface quality characteristics, surface roughness and material removal rate(MRR).6. The process rules of UEVCMHP were studied. The results showed that the integrate polishing technique could obtain better polishing surface qualities, more material removal and better no-smooth rate KR rate than the traditional chemistry machine polishing in the same conditions.In summary, hybrid polishing technique compared with tradition CMP has some improvement, whether in polishing surface quality or in MRR. There will be a important theory significance and project applicative values,which is rich in ultra-precise processing theory and enhances ultra-precise processing technique for the hard-brittle material.