Papers by Author: Yu Li Sun

Abstract: The necessity of fixed abrasive CMP in polishing semiconductor materials processing was analyzed. Compared the shortcomings of traditional free abrasive polishing with the advantages of fixed abrasive polishing, the applications of fixed abrasive polishing technology in semiconductor processing were described. A variety of fixed abrasive polishing pad production methods were introduced. The development trend of fixed abrasive polishing was prospected.

Abstract: A friction and wear experiment was carried out at different areas of single crystal silicon under same surface roughness. Friction mechanisms at different area were analyzed by STM and 3D profiler. The result showed that the friction and wear properties were obviously different at different area although they had same surface roughness. The friction and wear properties of the single crystal silicon where closest to inner-cycle internal were best while the farther from the inner-cycle silicon area or closer to crystal silicon cylindrical, the worse friction and wear properties were. Abrasive wear and adhesive wear were the primary wear mechanisms.

Abstract: The ice fixed abrasives (IFA) polishing is a potential polishing process in the semiconductor industry to realize superior surface finish and planarity for semiconductor wafers. The key question in IFA polishing is how to keep suitable ambient temperature and melting rate in production process in order to avoid premature failure of the IFA pad. In this paper, effects of ambient temperature (T), pressure in cylinder (Pc), rotary speed of IFA pad (v) and eccentricity of pressure head (e) on temperature distribution and melting rate of the IFA pad are researched. The results show that T should be kept at about 10 °C in order to control the melting rate of the IFA pad effectively and keep longer polishing time. And suitable Pc, e can be kept at 0.075 MPa or 0.1 MPa and 20 mm or 30 mm, respectively. In order to increase IFA polishing efficiency, the rotary speed of IFA pad can be increased appropriately. All the results provide the basis for choosing suitable processing parameters in IFA polishing.

Abstract: The experimental research on silicon was reported in this paper. The surface roughness under the different workpiece feed speed and linear velocity of the wire saws is studied mainly in this experiment. The effects of the workpiece feed Vs and the linear velocity of the wire saws Vw were analyzed.

Abstract: The key question in the ice fixed abrasives (IFA) polishing is how to keep suitable ambient temperature in production process in order to avoid premature failure of the IFA. Based on above, the three dimensions finite element analysis (FEA) model of IFA polishing temperature field is built up at first. Then, the model reliability is demonstrated by experiments. Effects of ambient temperature and polishing time on temperature distribution and melting rate of the IFA pad are researched. The results show that the ambient temperature should be kept at about 10 °C in order to control the melting rate of the IFA pad effectively and keep longer polishing time. All the results provide the basis for choosing suitable ambient temperature in polishing.

Abstract: The present paper describes research on stress in freestanding diamond thick film, diameter of 60mm, prepared on Mo substrate by DC arc plasma jet chemical vapor deposition (DCPCVD) method. The stress in the CVD diamond film was investigated by X-ray diffraction and Raman spectrum. The results show that the stress in the film is compressive. The stress changes little at the same homocentric round. The compressive stress along radial direction is that the stress in the centre of the film is lower than that in the edge at both the final surface and the original surface.

Abstract: Ice fixed abrasives (IFA) polishing is a novel ultra-precision machining method. The motion tracks of abrasives during IFA polishing have an important effect on the quality of the machined silicon wafer. Firstly, the motion tracks of IFA polishing are theoretically analyzed in this paper. It is founded that the paths of any point in the IFA polishing pad relative to the wokpiece are a group of cycloids. Then, the motion tracks of single abrasive and multiple abrasives in the IFA polishing pad are simulated respectively. The results show that increasing the eccentricity is beneficial to the enlargement of the size range of polishing process. With the increasing of the speed ratio between the IFA polishing pad and the workpiece, the abrasive at higher speed can leave longer tracks on the workpiece than that at lower speed at the same time. The more the abrasives, the more uniform the mark density under the influence of more abrasives.

Abstract: The exchange of the heat of the IFA polishing system was analyzed at first in this paper. Then the three-dimensional temperature finite element model was set up. By changing the material of the elements, the ice-melting process was simulated. It was found that the obtained simulating results showed a good agreement with the experimental results. The temperature distribution and the melting rate were studied in the case of different technical parameters, which can be used to provide references for choosing better parameters.

Abstract: The abrasive ice disc chemical mechanical polishing (AID-CMP) is a potential polishing process in the semiconductor industry to realize superior surface finish and planarity for semiconductor wafers. In this paper we investigated the temperature field during GaAs wafer AID-CMP process for a better understanding of AID-CMP. The results show that the AID outer temperature is higher than the inner, and the highest temperature in AID is at the wafer/AID contact zone. The increases of Pc, v, eh and tp will generate more energy and cause more local melting during GaAs wafer AID-CMP process. The AID temperature and the area of highest temperature zone increase with increasing Pc, v, and eh. The nodes temperature increase in every conditions adopted as tp increases. The area of melted zone and thickness of melted ice increase with increasing Pc, v, eh and tp.

Abstract: . In this paper, the model of fixed abrasive diamond wire saw has been set up, and its cutting mechanism has been discussed. Then, the material removal rate model and wire saw cutting efficiency model have been established. the speed of wire saw, the number of the dynamic effective abrasive and the workpiece feed rate have been analyzed to study their impaction on the stability of cutting process. Finally, some rules and suggestions were brought forward.