# Contact-Area-Changeable CMP Conditioning for Enhancing Pad Lifetime
## 3 Result and Discussion  
### Simulation Results of Pad Cut Rate Distribution  
The split conditioner proposed herein was compared with the disk-type conditioner (full contact) used for conventional CMP conditioning. The swing conditions of the conditioner used in the simulations are shown in Table 2. In the simulations, the conditioning time was 1 h, and the radial distribution of the pad wear rate was expressed by counting the number of times that the diamond grit of the conditioner passed a 10 mm \(\times\) 10 mm square drawn virtually on the polishing pad.  
Figure 5: Pad measurement system (PMS, G&P Technology, Busan, Korea).  
Figure 6: Procedure of conditioning and CMP experiment.  
Figure 7a-d show the simulation results of swing-arm pad conditioning. Figure 7a shows the pad cut rate profile when using the conditioner used in the general CMP process. [PERSON] et al. (2019) discovered that the average depth of the pad and the maximum depth of pad wear affected the MRR and WIWNU, respectively. If the condition of Case I is used in CMP conditioning, then the uniform wear of abrasive pads cannot be avoided. In particular, significant pad wear was observed in the section where the 200 mm diameter wafer used in this study (distance from pad center: 150-350 mm) was placed. The pad cut rate was obtained in the contact area of the wafer with the pad, as shown in Figure 7b, when the inner conditioner in Zones 2-5 was used to reduce excessive pad wear. Cases III and IV using the inner and outer ring-type conditioners exhibited considerable waviness in the pad cut rate profiles, as shown in Figure 7c,d, respectively. These results appear to be due to the possibility of obtaining a flatter pad profile if the conditioner has a smaller radius than the abrasive pad radius, as in [PERSON]'s study ([PERSON], 2018).  
The average values of the pad cut rate in the radial direction and the wafer-pad contact area of the four conditioning cases are shown in Figure 8a,b. Simulation results show that Case I with the conventional conditioning disk yielded a high average pad cut rate, whereas Case II yielded the lowest average pad cut rate among the four cases. Cases III and IV indicated a lower average pad cut rate than Case I, but the pad cut rate profile in the wafer-pad contact area exhibited waviness.  
Figure 7: Simulation result of pad cut rate distribution: (**a**) Case I (reference), (**b**) Case II, (**c**) Case III, and (**d**) Case IV.  
Figure 9 shows the maximum pad cut rate for the five conditioning cases. Figure 9a shows the maximum pad cut rate in the radial direction, and Figure 9b shows the maximum pad cut rate of the wafer-pad contact area. As shown in Figure 9a,b, the maximum pad cut rate in Case I was the highest, and Case II had the lowest maximum pad cut rate. In Case II, the inner conditioner, which had a small diameter, was used to reduce pad wear in Zones 2-5; consequently, excessive pad wear was shown in Case I, and the flatness of the pad cut rate profile improved using both the inner and outer ring-type conditioners in Zone 1. In the next section, we present the experimental study performed to investigate the pad lifetimes of Cases I and II.