Study On Material Removal Mechanism Of Wafer Chemical Mechanical Polishing In IC Manufacturing

Integrate circuit (IC) is the technology foundation of information industry and a key driving force promoting the development of the high technology. Chemical mechanical polishing (CMP) has been considered as a practical and irreplaceable planarization technology of wafer in IC manufacturing. It is not only the most effective method of achieving ultra-smooth and non-damage surface in manufacturing monocrystalline silicon wafer, but also the ideal method of realizing local and global planarization of wafer in the multi-level wiring process of the metal interconnects for ultra large scale IC (ULSI). Nowadays, CMP technology has been widely used in ULSI manufacturing.Accurate control of CMP process depends on, to a great extent, understanding of the material removal mechanism in wafer CMP. However, the CMP mechanism, such as material removal mechanisms, form mechanism of the material removal nonuniformity and influencing law of the process variable on material removal, have not been understood completely. The control of CMP process has mainly been depending on the semi-empirical or empirical means. It is difficult to improve CMP process to gain greater material removal rate and higher wafer surface quality. With the decrease of feature size and the increase of integration level of IC chip, CMP technology is facing higher demand and new challenge. The present CMP technology is incapable of meeting the needs of wafer surface quality in next generation IC. Study on the CMP mechanism becomes an important fundamental research work to improve the CMP technology.In this dissertation, the material removal mechanism of wafer CMP has been studied from such aspects as the contact form between the wafer and the pad, the friction and wear behavior of the wafer surface and the abrasive motion trajectory on the wafer surface. The main contents and results are as follows:An identifying approach to the contact form between the wafer and the pad has been put forward based on the friction and wear theory. According to the research results on the behavior of the friction and wear on the wafer surface material, it is concluded that the contact form between the wafer and the pad is solid contact, the polishing pressure is entirely supported by the asperity of the pad and the lubrication status on the wafer surface is chemistry boundary lubrication.