Contact Mechanism Of Self-regressive Fixed Abrasive Polishing Pad In Chemical Mechanical Polishing

With the continuous advancement of technology,third-generation semiconductor materials(such as Si C)have become fundamental materials for the current high-tech industry in the information society and are widely used in many fields because of their more desirable photoelectric conversion capability and microwave signal transmission efficiency.Chemical mechanical polishing(CMP)technology is one of the most effective techniques to achieve global flattening of hard and brittle material surfaces such as semiconductor materials.According to the role of abrasives in the CMP process,it can be divided into free abrasive chemical mechanical polishing and fixed abrasive chemical mechanical polishing.Compared with free abrasive chemical mechanical polishing,fixed abrasive chemical mechanical polishing has the advantages of high processing efficiency,low cost of consumables,environmental protection and no pollution,etc.As an important part of the fixed abrasive chemical mechanical polishing,fixed abrasive polishing pads are the main factor affecting the efficiency and processing effect of fixed abrasive chemical mechanical polishing.In this paper,on the theoretical basis of the subject group on self-regressive fixed abrasive polishing pad,the influence of the ingredients of self-regressive fixed abrasive polishing pad on their contact properties is studied,and the ingredients are reasonably optimized.At the same time,the contact mechanism and processing advantages of self-regressive fixed abrasive polishing pads are further elucidated by establishing the contact model of self-regressive fixed abrasive polishing pads in chemical mechanical polishing,combined with the simulation analysis of the contact model of single and multiple diamond abrasive grains in the self-regressive fixed abrasive polishing pad matrix.The main research contents are as follows:(1)The influence of the ingredients of self-regressive fixed abrasive polishing pad on its contact properties.The influence of the selection and content of each ingredient in the preparation of self-regressive fixed abrasive polishing pads on their contact properties was investigated by the single-factor test method.The elastic modulus,Shore hardness and swelling rate of self-regressive fixed abrasive polishing pads were used as characterization methods,combined with the material removal rate of the machined workpiece before and after the CMP test and the two-dimensional and three-dimensional morphological comparison,to comprehensively analyze and evaluate the contact performance of self-regressive fixed abrasive polishing pads.The results showed that: When the elastic modulus of self-regressive fixed abrasive polishing pad is 683.2～761.4 MPa,Shore hardness is 58.9～65.2 HD,and the swelling rate is 9.41～11.44%,it has better contact performance and polishing effect.A new formulation for the preparation of self-regressive fixed abrasive polishing pad is proposed.(2)Contact model for self-regressive fixed abrasive polishing pad in chemical mechanical polishing.By establishing the contact model of self-regressive fixed abrasive polishing pad in chemical mechanical polishing,combined with the theory of probability density function,critical deformation amount formula of elastic-plastic deformation,Hertzian contact,uniform distribution,etc.,we investigated the effect of self-regressive fixed abrasive polishing pad characteristics on the number of raised abrasive grains on its surface,the setback distance of the abrasive grains in the polishing pad matrix,and the depth of the abrasive grains into the workpiece.The results showed that: The amount of polishing pressure as well as the hardness,elastic modulus and abrasive content of self-regressive fixed abrasive polishing pad are important factors affecting its contact properties.(3)Contact simulation of single and multiple diamond abrasive grains in the self-regressive fixed abrasive polishing pad.Using finite element simulation software,the receding distance of a single diamond grain in the self-regressive fixed abrasive polishing pad and the variation of its entry depth in the Si C single crystal wafer were analyzed for different grain sizes and different polishing pressures,and the variation of the retreat distance of multiple diamond grains in the self-regressive fixed abrasive polishing pad for different outcrop heights and different grain sizes.The results showed that: The self-regressive fixed abrasive polishing pad surface raised higher abrasive grain under the action of polishing pressure,can continue to occur setback distance phenomenon.Until the abrasive grains with lower projection are equal in height,so that the surface of the workpiece can contact more abrasive grains during the polishing process,thus improving the processing efficiency and polishing effect of CMP.