Fabrication Mechanism And Key Technology Of Sapphire Double-sided Chemical Mechanical Polishing

With the continuous expansion of the LED chip market scale and the downstream application market demand,the diversified demand for the sapphire substrate is correspondingly increasing,which puts forward new requirements and challenges for the establishment of matching process procedures.However,due to the obvious anisotropy of sapphire materials and the complex correlation of various processing factors in the chemical mechanical polishing process,which is difficult to be directly characterized,and the lack of sufficient analysis and support of process test results,the existing theoretical understanding of the double-sided chemical mechanical polishing of sapphire with different crystal orientations cannot meet the effective control of the industrial practice process,while can only consume time,manpower and financial resources to carry out massive process experiments.Therefore,it is necessary to carry out the research based on the difference in mechanical response and damage mechanism of sapphire with different crystal orientations in the first place.Then,the mechanism of double-sided chemical mechanical polishing of sapphire with different crystal orientations needs to be revealed.Furthermore,the exploration of the sapphire double-sided chemical-mechanical polishing surface morphology generation mechanism is conducted.Finally,an intelligent decision-making framework is built with quality and efficiency-oriented for sapphire double-sided chemical mechanical polishing.It is expected to lay a solid foundation for ensuring the consistency of sapphire substrate processing,improving the efficiency of sapphire substrate processing,and realizing the intellectualization of the sapphire substrate chemical-mechanical polishing process.Therefore,the main research contents of this paper include the following aspects:(1)Starting from indentation and scratch experiments and simulations of sapphire materials,the mechanical response and damage mechanism of sapphire are explored.The crystal structure characteristics and quantitative characterization methods of sapphire with different crystal orientations are introduced.The quasi-static Vickers indentation performance of sapphire was investigated including the analysis of the indentation morphology,indentation crack determination,indentation mechanical properties,and indentation dynamic crack propagation.The dynamic scratch performance of sapphire under the "time-distance" effect was studied,containing the establishment of single,double and multiple scratch stress fields,the development of micro-nano scratch experiments,and the revelation of the single,double and multiple scratch material removal mechanism under the "time-distance" effect based on the stress field analysis method,laying a solid foundation for the follow-up study of the mechanism of double-sided chemical mechanical polishing of sapphire.(2)The material removal process of double-sided chemical mechanical polishing of sapphire was analyzed,and the processing mechanisms at different levels was revealed.The modeling method of the sapphire double-sided chemical-mechanical polishing mechanism was established.And the material removal process was analyzed and modeled from three levels,namely,nano-view,micro-view,and macro-level,respectively.The solid-liquid two-phase diffusion process,chemical reaction ability,the contact between polishing pad asperities and sapphire,the contact between polishing pad asperities embedded with abrasives and sapphire,the three-body wear between abrasives and sapphire,and the material removal of different trajectories were all analyzed and modeled in detail.The comprehensive material removal process of sapphire chemical-mechanical polishing is analyzed,and the validity of the theoretical analysis and modeling in this paper is verified by the orthogonal experiments of double-sided chemical-mechanical polishing of sapphire with different crystal orientations.(3)Based on free abrasive motion trajectory simulation,three-dimensional topography simulation of double-sided chemical mechanical polishing was carried out.The overall simulation method of sapphire double-sided chemical-mechanical polishing three-dimensional morphology is established,and the kinematics characteristics of double-sided chemicalmechanical polishing are modeled based on the basic parameters of the double-sided polishing machine.Kinematics numerical analysis and abrasive motion trajectory simulation are carried out for sapphire double-sided chemical mechanical polishing.Combined with the removal depth of the abrasive track considering the removal characteristics of sapphire material simultaneously,the mesh of abrasive track pixels,and the initial shape evolution matrix iteration,the three-dimensional morphology simulation is realized for sapphire double-sided chemical-mechanical polishing.(4)Based on the basic theory of intelligent decision-making for sapphire double-sided chemical mechanical polishing,the application of intelligent decision-making for polishing processing is realized.The basic theory of sapphire double-sided chemical-mechanical polishing intelligent decision-making is put forward,which includes the establishment of process intelligent decision-making framework,process case representation,attribute reduction based on three-way decision theory,feature attribute weight calculation based on the synthesis of the subjective and the objective weight,process case similarity calculation based on casebased reasoning,process plan optimization based on heterogeneous integration learning,and process case evaluation.The application of sapphire double-sided chemical-mechanical polishing intelligent decision-making is realized through the sapphire double-sided chemicalmechanical polishing experiment,intelligent decision-making process example,processing verification,and software and interactive application.The intelligent process software of sapphire chemical mechanical polishing,including the data perception layer,state recognition layer,underlying data knowledge,data knowledge management,system function module,and application & interaction system,is proposed for the technical support to realize the quality and efficiency controllable processing of sapphire wafer double-sided chemical mechanical polishing,to improve the production efficiency of the sapphire wafer and to promote the upgrading of sapphire wafer industry.