A Method to Improve Uniformity of Material Removal of Chemical Mechanical Polishing in LCOS Process

摘要

LCOS panel as a kind of new LCD is a sort of liquid crystal display device that operates in a reflective mode. In this paper, a method on realising planarization in large scale liquid crystal on silicon with chemical mechanical polishing (CMP) technology is discussed in detail. The non-uniform distributions of polishing pressure and the relative speed between the wafer and the polishing pad are main factors affecting the within-wafer non-uniformity. This research integrated a physical mixed model of chemical-mechanical polishing that combineed the effects of polishing pad roughness and slurry hydrodynamic pressure. Based on the contact mechanics and modified Reynolds equation, the asperity contact and fluid flow pressures were calculated. Taking into account the effects of kinematic parameters, the material removal rate(MRR) on silicon panel front surface was obtained. In the last section the design of a schematic carrier with multi-zone, in which the compensation back pressure can be applied, is presented. The model and the design can be used for providing theoretical guide to the development of CMP equipments and selection of the kinematic variables in CMP process.