Synthesis And CMP Behavior On Silicon Wafer Of Composite Abrasives CeO₂-CeLa₂O₃F₃

Chemical mechanical polishing (CMP) is a only global planarization technology, plays an important role in the preparation process of ULSI. The key technology of CMP is the preparation of polishing slurry, the key technology of polishing slurry is the preparation of abrasive in slurry. Preparation of composite abrasives has become a hot topic in the CMP area in recent years gradually, because composite abrasives own all kinds of advantages from single abrasive and improve their disadvantages. Composite abrasives include doping composite abrasives and coating composite abrasives. In this paper, best process conditions were searched and high quality doping composite abrasives CeO2-CeLa2C2O3F3were synthesis. Single crystal silicon, multicrystal silicon and K9glass were polished by composite abrasives CeO2-CeLa2O3F3. The best process conditions and reason of increasing the material removal rate were investigated.A series of different fluorine contents composite abrasives CeO2-CeLa2O3F3were synthesized by chemical precipitation method by using cerium chloride and lanthanum chloride as raw material, ammonium fluoride as fluridizer, ammonia sulfate as modifier and ammonium bicarbonate as precipitating agent. The phase structures, surface morphologies and particle size distribution of the as-prepared samples were analyzed by X-ray diffraction(XRD), scanning electron microscope(SEM), particle size analyzer. The effect factors of fluridizer, modifier, precipitation temperature, the added way of fluridizer, calcination temperature on the particle size were investigated. The results indicated that the minimum tap bulk density of composite abrasives CeO2-CeLa2O3F3was obtained by using ammonium fluoride as fluridizer,7wt.%fluorine content, ammonia sulfate as modifier, precipitating at80℃, adding in fluoride before precipitation, calcining at1000℃. The minimum tap bulk density was0.68g/cmj, the particle size was350nm, the particle was spherical and distributed uniformly.The material (single crystal silicon, multicrystal silicon, K9glass) was polished by the high quality composite abrasives CeO2-CeLa2O3F3. The various kinds effect factors on the material removal rate(MRR) were investigated. The polishing performance of composite abrasives CeO2-CeLa2O3F3was characterized by using atomic force microscope(AFM) and scanning electron microscope(SEM). The results showed that the maximum MRR was obtained by doping7wt.%fluorine content, precipitating at80℃, calcining at1000℃. The MRR was larger by using ammonia sulfate as modifier than diammonium phosphate. The MRR was larger by adding fluridizer before precipitation than after. The MRR increased with the increase of pH value(The maximum MRR of K9glass was obtained at pH=8). The MRR increased with the increase of pressure. The MRR decreased with the increase of the mass of cerium hydroxide in the polishing slurry. The MRR increased with the increase of calcination time. AFM morphologies showed that the polished material surface became super smooth and micro-scratch could hardly be observed.