Papers by Author: Xi Qu Chen

Abstract: An automatic washing machine vibrates with lager amplitudes and noise during the spin-dry cycle, which affects human health and machine reliability. In this paper, we are interested in the study of the dynamic performance of a drum washing machine, with springs top-mounted and dampers bottom-mounted. A novel model for simulation of the dynamic performance of the drum washing machine was developed under MSC.ADAMS software package. Next, simulations and validations were performed. The simulation results indicated good agreement with the mechanical performance of the actual test system, which demonstrated the validity of the dynamic model to predict the displacements of the tub center during the spin-dry cycle. Moreover, the developed model was capable of successfully simulating drum washer operating test for various dynamic responses of the given parts by building Measures or using Markers at the transient or steady-state, which could afford better support for designers to explore the robustness of the cabinet.

Abstract: Based on experiments of common drilling and vibration drilling on duralumin (2A12), the failure mode and failure reason of twist drill are studied theoretically and experimentally. The result shows that, compared with common drilling, the wear of clearance face and rake face decreases evidently during vibration drilling, and the wear of chisel edge and marginal point of twist drill hardly happens. Moreover the probability of drill breakage is very low during vibration drilling. However, if amplitude is bigger, the tipping of chisel edge often appears.

Abstract: The components of material removal in wafer Chemical mechanical polishing (CMP) was described qualitatively based on theory of corrosive wear. The value of each component was obtained by a series of wafer CMP experiments. According to analyzing the experiment results, some conclusions are obtained as follows. There is an optimum polish velocity in wafer CMP at a certain parameter. Under the optimum velocity, the balance of interaction between the mechanical action and the chemical action is reached and the material removal rate approaches maximum. The wafer CMP is a changeful and dynamic process. It cannot be obtained ideal effect of material removal by increasing the mechanical action or chemical action only. The MRR in wafer CMP mainly depends on the interaction result between the mechanical action and the chemical action and the interaction made by abrasives is a decisive part. These results provide a theoretical guide to further understanding the material removal mechanism in wafer CMP.

Abstract: Chemical mechanical polishing (CMP) has already become a mainstream technology in global planarization of wafer. The nonuniformity of material removal on wafer surface has a main influence on surface profile of silicon wafer in CMP process. However, the formation mechanism of nonuniformity in wafer CMP has not been fully understood and the influences of CMP process variables on nonuniformity are not fully clear. The nonuniformity of material removal on wafer surface has not been fully understood and the influences of CMP process variables on nonuniformity are not fully clear in CMP process. In this paper, firstly, the equation of particle movement trajectories on wafer surface was built by the movement relationship between the wafer and the polishing pad on a single head CMP machine with line oscillation of carrier. Then the distribution of abrasive trajectories on wafer surface was analyzed at different rotational speed. By the analysis, the relationship between the movement variables of the CMP machine and the With-In-Wafer Nonuniformity (WIWNU) of material removal on wafer surface had been derived. Last, the WIWNU tests were conducted on CP-4 machine. The analysis results are in accord with experimental results. The results will provide some theoretical guide for designing the CMP equipment, selecting the movement variables in CMP and further understanding the material removal mechanism in wafer CMP.

Abstract: Right getting hold of the contact form between the wafer and the pad is the precondition of fully understanding the material removal mechanism in wafer chemical mechanical polishing (CMP) process. In this paper, according to friction and abrasion theory, the differentiating method of contact form between the wafer and the pad has been obtained firstly. Then, the material removal rate (MRR) produced by mechanical action, chemical action and their interaction has been achieved by test results of MRR. According to analysis on test results of MRR, it is concluded that the mechanical action produced by abrasives is the main mechanical action, the MRR produced by the interaction between the mechanical action of abrasives and chemical action of slurry is the main MRR and the contact form between the wafer and the pad is solid-solid contact in wafer CMP. These results will provide theoretical guide to further understand the material removal mechanism of in wafer CMP.