Papers by Author: Yin Xia Zhang

Abstract: The friction force on wafer surface plays an important role in removing material of wafer surface and the friction force on wafer surface may have a direct influence on non-uniformity of material removal in wafer CMP process. In this paper, models of friction force on wafer surface were built according to the CMP process. It is proved that the model of the friction force on the wafer surface is correct by the silicon wafer CMP Friction experiment. Then the data fitting of friction model has been done with the experimental data. By the friction force model, the within wafer nonuniformity (WIWNU) of friction force distribution on wafer surface has been obtained with different rotational speed of wafer and polishing pad. The research of this paper is helpful to further understanding the material removal mechanism in wafer CMP.

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: In order to better understand the grinding mechanism, the rough, semi-fine and fine ground silicon wafer subsurface damage models are experimentally investigated with the aid of advanced measurement methods. The results show that the rough ground wafer subsurface damage model is composed of large quantity of microcracks with complicated configurations, high density dislocations, stalk faults and elastic deformation layer. Among them microcracks, dislocations and stalk faults are dominant. Apart from the above damage, the amorphous layer and polycrystalline layer (Si-I, Si-III, Si-IV and Si-XII) exist in the semi-fine ground and fine ground wafer subsurface damage models. The amorphous layer depth firstly increases from rough grinding to semi-fine grinding and then decreases from semi-fine grinding to fine grinding. The damage model can be divided in severe damage part and elastic deformation part with high stress. When the material is removed by ductile mode two parts are all small and the ratio of second part is relatively great.