Study On Composition Optimization And Performance Of Self-Retreating Fixed Abrasive Polishing Pad

Chemical Mechanical polishing(CMP)was first proposed in the mid-1960s as the only technique to achieve local and global flattening of Very Large Scale Integration Circuit(VLSI)today.At the end of the twentieth century,solidified abrasive polishing technology emerged.With the further enhancement of processing requirements,solidified abrasive polishing pads with self-curing function were developed,represented by freeze-curing related materials and UV-curing polymer material technology.However,the use conditions of polishing tools based on freezing technology are harsh;The self-regressive solidified abrasive polishing pad prepared based on UV curing technology has poor toughness,short lifespan,and significant shape changes during the pad forming process.Therefore,based on the previous research of our group,this paper further optimizes the composition and process of self-receding solidified abrasive polishing pads,and systematically investigates in depth the influence of substrate characteristics on processing performance.The main research content is as follows:(1)The ratios of the base components of the polishing pad were adjusted using the orthogonal test method.By changing the ratios of aqueous polyurethane,light-curing resin,two reactive diluents and photoinitiator,five formulations with suitable base characteristics and regular shape were selected.In these five formulations,the content of water-based polyurethane(WPU)was always greater than that of light-curing resin,and the polishing pads obtained from the other 11 formulations were brittle and unshapable,indicating that the ratio of WPU and light-curing resin played a decisive role in the shaping of the pads,and the ratio of the two should be less than 0.92.(2)To explore the effect of two modifiers,NBR and copper powder,on the characteristics of polishing pad substrates.The orthogonal test results show that the addition of nitrile rubber can increase the Young’s modulus or elasticity of the polishing pad and reduce the hardness of the substrate;the addition of copper powder will reduce the Young’s modulus of the polishing pad and increase the hardness and reduce the elasticity;the addition of two modifiers has no direct effect on the swelling rate of the substrate.Too much nitrile content will lead to too much elasticity and not enough hardness,which will seriously affect the sharpness of the polishing pad;the content of both nitrile rubber and copper powder should be controlled at about 3wt%.(3)Through the single-factor test of changing the abrasive content in the polishing pad,it was found that the unrestricted increase of abrasive content does not bring the continuous improvement of material removal rate or the improvement of the processed surface quality;the abrasive content in the polishing pad is controlled at 10%-20% which is more suitable.(4)The influence of polishing pad substrate characteristics on the quality of workpiece processing.The test proves that the change of Young’s modulus has little effect on the processing performance of polishing pad;higher hardness of polishing pad can bring higher material removal rate;too much elasticity will seriously affect the self-sharpening of polishing pad,which has adverse effect on the material removal rate of polishing pad and the quality of processed surface.(5)The effect of polishing pad substrate soaking time on the polishing effect.Polishing pad chosen by the base composition of the swelling rate in 180 minutes of immersion generally reached 25%-35% of the range after stabilization.After a large number of tests to prove that the soaking time of 20 minutes polishing pad "concession" effect has reached a more ideal state.Polishing pad soaking length of more than 20 minutes after the dissolution rate of the material to remove the rate and the surface quality of the processed workpiece has no effect.(6)Life study of polishing pads.The life of the modified polishing pad was substantially improved,with good material removal rate and workpiece surface quality after nearly 3 hours of use.