# Contact-Area-Changeable CMP Conditioning for Enhancing Pad Lifetime
## 2 Experimental Set-Up  
### CMP Conditioning System and Condition  
Figure 2 shows the design of the CMP conditioning system incorporated with a split conditioner. In the newly designed CMP conditioning system, the pneumatic cylinder controls the height of the conditioner. The conventional CMP conditioner (SAESOL DIMAMOND Ind. Co. Ltd., Ansan, Korea) is separated by waterjet cutting. The conditioner comprises an inner conditioner and an outer ring-type conditioner.  
The diameter of the inner conditioner was 64 mm, and the width of the outer ring-type conditioner was 31 mm. The gap between the two conditioners was 2.5 mm. The loads acting on the inner and outer conditioners were independently controllable and rotated at the same rotational speed using a rotary joint.  
The rotational speeds of the platen and conditioner were 93 and 101 rpm, respectively. The conditioning load was 4 kgf. The swing-arm's swing count was fixed at nine sweeps per minute. The specific conditioning conditions are listed in Table 1.  
The swing-arm's swing movement was partitioned into five zones in the radial direction above the polishing pad. The CMP conditioning system used in the experiment regulated the swing motion of the conditioner with the duration time (%) in the zones above the polishing pad. In this study, the same conditioner duration time was used throughout the entire zone to exclude the effect of the swing motion on the pad wear profile. Table 2 shows the conditioner duration times in the conditioning zones.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Condition (Unit)** & **Value** \\ \hline Rotational speed of platen (rpm) & 93 \\ Rotational speed of conditioner (rpm) & 101 \\ Conditioning load (kgf) & 4 \\ Sweep per minute (sweep/min) & 9 \\ Swing start radius (mm) & 370 \\ Swing end radius (mm) & 50 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Conditions for CMP conditioning.  
Figure 2: Swing-arm conditioning system and split conditioner used in this study.  
In Figure 3, \(P\) means an arbitrary point on the conditioner disk. \(r_{p}\) and \(r_{s}\) are the position vectors of the position \(P\) on the conditioner and rotating axis of swing-arm relative to the pad. \(r_{a}\) and \(r_{c}\) are the local position vectors of conditioner rotating center and the position \(P\) on the conditioner. \(\omega_{c}\), \(\omega_{a}\), \(\omega_{p}\), and \(\omega_{w}\) are angular velocity vectors of conditioner, swing-arm, pad, and wafer, respectively. The \(r_{p}\) can be calculated from Equation (1) [35].  
\[r_{p}=r_{s}+r_{a}+r_{c} \tag{1}\]  
During the simulation, the total number of diamond grits on the conventional conditioner was 468 ea. For the split conditioner, the numbers of diamond grits on the inner and outer ring-type conditioners were 200 and 268 ea, respectively. It was assumed that the diamond grit on the conditioner was evenly arranged and the polishing pad in its initial state was ideally flat. The unit density inspection area was 10 mm\({}^{2}\). For a fair comparison with the experimental results, the pad wear simulation was performed with 1 h of conditioning. The calculation interval was set to 0.01 s in the pad wear profile simulation. The radial profile of the pad cut rate profiles was calculated for comparison with the experimental results. In this study, the conditioning conditions of four cases were considered, as shown in Table 3.