With the development of integrated circuit technology, especially after entering the sub-micron process, the reduction of critical dimensions and the realization of high-density devices, the flatness between integrated circuit material layers is becoming more and more critical. Because conventional mechanical polishing methods inevitably produce scratches of the same size as the device in metal or even dielectric layers, resulting in depth of field and focus problems in lithography. The first planarization technique to achieve application is spin on glass (SOG) technology. However, this technology will not only introduce new material layers, but will also fail to achieve the global flattening required by VLSI and ULSI technologies. Moreover, the process instability and uniformity during spin coating do not meet the high flatness requirements of the wafer surface. Also, while some techniques such as reverse etching and glass reflow can achieve submicron level regional planarization. After the critical dimension reaches 0.35 microns (sub-micron process), the above methods cannot meet the requirements of lithography and interconnect fabrication. In the 1980s, IBM first introduced the chemical mechanical polishing (CMP) technology used to manufacture precision optical instruments into its DRAM manufacturing [1]. With the development of technology nodes and critical dimensions, CMP technology has been widely used in the Front End Of Line (FEOL) and Back End Of Line (BEOL) processes [2]. Since the invention of chemical mechanical polishing, scientists have not stopped studying its internal mechanism. From the earliest Preston Formula (1927) to today’s wafer scale, chip scale, polishing pad contact, polishing pad - abrasive - wafer contact and material removal models, there are five different scale models from macro to the micro [3]. Many research methods, such as contact mechanics, multiphase flow kinetics, chemical reaction kinetics, molecular dynamics, etc., have been applied to explain the principles of chemical mechanical polishing to establish models. This paper mainly introduces and summarizes the different models of chemical mechanical polishing technology. The various application scenarios and advantages and dis-advantages of the model are discussed, and the development of modeling technology is introduced.

Chemical mechanical polishing (CMP), as a widely used planarization technology, requires high removal rate and low surface roughness generally. However, it is difficult to meet these requirements in a single-step polishing process. To get an ultrasmooth surface of the sapphire substrate, we investigated a two-step CMP of the sapphire substrate using ultrafine α-alumina-based slurry and nanoscale silica-based slurry. Also, in situ coefficient of friction (COF) measurements were conducted. The results show that during the first-step polishing in the alumina-based slurry, the COF decreases with polishing time first and then tends to be a constant; a relatively high material removal rate was reached, and the root-mean-square (rms) roughness value of the polished surface can be decreased from 968.9–21.98 Å. In the second-step CMP, the nanoscale silica slurry was adopted; the COF increased in the first minute of polishing and then became stable too, and the rms roughness of the sapphire substrate surfaces can be further reduced to 6.83 Å by using the optimized process parameters. In addition, the CMP mechanism of sapphire using the above two slurries was deduced and documented preliminarily.

Chemical mechanical polishing (CMP), as a widely used global smoothing technique, requires a high polishing rate and a low surface roughness. However, it is difficult to meet these requirements with single-step polishing. To obtain a perfect 4H-SiC wafer surface, we studied a two-step CMP 4H-SiC wafer using a-Al ₂ O ₃ -based slurry and nano-SiO ₂ -based slurry. Before the two-step process was determined, the effect of concentration of KMnO ₄ and pH on the polishing rate of 4H-SiC was first studied with Al ₂ O ₃ as the abrasive, and the maximum polishing rate of 1400 nm h ⁻¹ was determined under the condition of pH of 2.00 and KMnO ₄ concentration of 6.5 wt% in the step. Furthermore, the effect of H ₂ O ₂ concentration on the polishing rate of 4H-SiC was investigated using SiO ₂ as the abrasive and V ₂ O ₅ as the catalyst. It was determined that under the condition of V ₂ O ₅ concentration of 4 wt% and H ₂ O ₂ concentration of 10 wt%, the maximum polishing rate of the second step polishing was 150 nm h ⁻¹ , and a perfect surface was obtained, with a surface roughness of 0.066 nm. In addition, the in situ friction coefficients have used to characterize the two-step process. At the end, the CMP mechanisms of the above two slurry have been deduced and preliminarily demonstrated.