# Contact-Area-Changeable CMP Conditioning for Enhancing Pad Lifetime
###### Abstract  
Chemical-mechanical polishing (CMP) is a process that planarizes semiconductor surfaces and is essential for the manufacture of highly integrated devices. In CMP, pad conditioning using a disk with diamond grit is adopted to maintain the surface roughness of the polishing pad and remove polishing debris. However, uneven pad wear by conditioning is unavoidable in CMP. In this study, we propose a contact-area-changeable conditioning system and utilize it to conduct a preliminary study for improving pad lifetime. Using the conventional conditioning method (Case I), the material removal rate (MRR) decreased rapidly after 12 h of conditioning and the within-wafer non-uniformity (WIWNU) increased. However, the results of conditioning experiments show that when using a contact-area-changeable conditioning system, uniform pad wear can be obtained in the wafer-pad contact area and the pad lifetime can be extended to more than 20 h. Finally, the newly proposed conditioning system in this study may improve the CMP pad lifetime. chemical mechanical polishing (CMP); pad conditioning; pad wear profile; pad lifetime +
Footnote †: : 2021: 11, 3521. [[https://doi.org/10.3390/app11083521](https://doi.org/10.3390/app11083521)]([https://doi.org/10.3390/app11083521](https://doi.org/10.3390/app11083521))
However, pad wear is unavoidable because a diamond conditioner is used in swing-arm pad conditioning [30, 31]. In particular, uneven pad wear affects the MRR and within-wafer non-uniformity (WIWNU). [PERSON] et al. [32] proposed a mathematical model of oscillation-type CMP conditioning. They used dimensionless parameters to perform integration in the calculation of sliding distances of diamond grits. [PERSON] et al. [33] also proposed a mathematical model for oscillation-type CMP conditioning. They found that the smaller the radius of the diamond conditioner compared to the radius of the polishing pad, the higher the uniformity of the pad profile. However, the proposed methods in the studies of [PERSON] et al. and [PERSON] et al. were not applicable in swing-arm conditioning. According to [PERSON] et al. [34], pad conditioning generally results in a \"W\"-shaped pad profile. They simulated the pad wear profile with a mathematical approach based on the geometry and moving motions during swing-arm CMP conditioning. According to their experiment, the profile of the polishing pad was related to the profile of MRR at CMP, and they showed that the shape of the polishing pad profile and the MRR profile had the opposite shape. They explained that the difference between experimental result and simulation may come from the moment that the friction forces act on the conditioner disk. [PERSON] et al. [35] simulated swing-arm CMP conditioning via kinematic modeling and showed that the swing-arm velocity profile (SAVP) affected the pad profile. They calculated the pad wear profile by drawing a virtual concentric circle on the surface of the pad and summing the sliding distance of the conditioner's diamond grits passing through the virtual area. They considered five cases of SAVP and found that the convex-shaped SAVP aided in the flatness of the polishing pad during CMP conditioning. [PERSON] et al. [30] also predicted pad profile after CMP conditioning by using a surface element method. They reported that the difference between the predicted pad profile and the pad profile measured by the experiment may come from the set-up of the experiment, the deformation of the pad, and the surface uneveness. [PERSON] et al. [36] investigated the relationship between pad profile after pad conditioning and CMP results (MRR and WIWNU) using a pad measurement system (PMS). They discovered that the average depth of pad wear affected the MRR and that the maximum depth of pad wear affected the WIWNU. According to [PERSON] et al., the concave-shaped profile of a conditioner's duration time in swing-arm conditioning can enhance the pad lifetime. [PERSON] et al.