AbstractWith 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.

Cobalt, the 3rd generation material for interconnect in deep nanometers' processing. Cobalt reduces the interconnect structure and process complexity compared to the dual damascene process. In this article, we investigate the effects of complexing agent L-Aspartic acid (L-Asp) and oxidant H 2 O 2 for polishing Cobalt based on chemical mechanical polishing (CMP). The results show that the water-soluble Co(III)-L-Asp complex generated by adding L-Asp and H 2 O 2 is beneficial to improve the Cobalt removal rate. Electrochemical measurements and X-ray photoelectron spectroscopy are ultilizd to explore the removal mechanism of Cobalt. The high removal rate of Cobalt may be attributed to the formation of [Co(C 4 H 5 NO 4 ) 2 −] and [Co(C 4 H 5 NO 4 ) 2 2− ] complexes. The surface morphology of cobalt is observed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The results show that obvious corrosion phenomenon appears on the surface of cobalt after adding H 2 O 2 and L-Asp, which also confirms the chemical reaction mechanism in which the removal rate is improved as previously analyzed.

In this study, we investigate the chemical mechanical planarization (CMP), static dissolution and electrochemical performace of amorphous carbon-doped Ge 2 Sb 2 Te 5 (GSTC) film in alkaline slurry with H 2 O 2 employed as an oxidizer. It was found that the material removal rate (MRR) of GSTC first increase and then slowly decrease with the increase in concentration of H 2 O 2 . The surface quality of the GSTC post-CMP shows the same trend. To understand the mechanism of GSTC CMP with H 2 O 2 , the Energy Dispersive Spectrometer on the surface of the GSTC post-CMP, Inductively Coupled Plasma of the solution after static dissolution, potentiodynamic polarization curve and X-ray photoelectron spectroscope are measured and it is found that the change in carbon state is an important factor for the CMP of GSTC. Finally, a possible removal mechanism of GSTC in different concentrations of H 2 O 2 in the alkaline slurry is proposed.

Titanium nitride (TiN) is preferred for use as the bottom electrode contact due to its excellent thermal stability and suitable electrical conductivity. We have studied the effect of using potassium permanganate (KMnO 4 ), L-Aspartic Acid (L-Asp) and alumina abrasives as slurry in chemical mechanical polishing (CMP) of TiN film. Different concentrations of potassium permanganate and different concentrations of L-aspartic acid additives were applied to the CMP of TiN. The results show that KMnO 4 and L-Asp can increase removal rate and improve the surface smoothness of TiN. The removal mechanism of TiN was analyzed by XPS and electrochemical tests, and the TiN film was characterized by atomic force microscope and scanning electron microscope.