The effect of conditioning downforce during pad break-in, and its impact on the evolution of pad surface micro-texture was investigated. Two different conditioning downforces were used to break-in pads. Pad samples were extracted after certain break-in times and analyzed for their topography and contact area using confocal microscopy. Results showed that the pad-wafer contact area and contact density decreased with conditioning downforce. Break-in at the higher conditioning downforce helped in reaching faster stabilized values of the analyzed micro-texture parameters. The evolution of these parameters was different for the two different downforces, however as break-in time increased past 30 minutes, mean summit height and mean summit curvature began to approach approximately the same value. These results indicated that, for the particular disc used in this study, a change in the magnitude of downforce during pad break-in caused a change in break-in time and stable values for some micro-texture parameters. However, a

The impact of conditioner types and downforces during pad break-in, and the resulting effects on the evolution of pad surface micro-texture was investigated. Two different conditioning discs were used with 3 possible downforces to break-in pads. Pad samples were extracted throughout the break-in process and confocal microscopy was used to analyze the samples for their surface microtopography and pad-wafer contact. Results showed that all experimental cases resulted in similar trends of mean summit height. More importantly, each case resulted in a different evolution of summit height distribution. Comparing the two discs used, one disc was observed to be more sensitive to changes in downforce compared to the other. The differences in the behavior of the two discs is explained by the differences in cutting mechanics, which is due to the different characteristics of the two discs. Both discs generated large amounts of pad fragments, which were shown to cause pore obscuration on the pad surface. In 4 out of 5 cases, the pad surface micro-texture stabilized within 30 minutes of break-in and all cases stabilized within 60 minutes. This work demonstrated the importance of understanding how different conditioner types react to changes in downforce when breaking-in a pad.

The effect of different types of conditioners used during tungsten chemical mechanical planarization (CMP) on frictional, thermal, and kinetic aspects of the process was investigated. Based on previous work, regarding the effect of conditioner type and downforce on the evolution of pad surface micro-texture during break-in, two significantly different discs were employed (i.e. conventional vs. CVD-coated). First, mini-marathon style tungsten CMP runs were conducted for each disc. These were followed by tungsten polishing at various pressures and velocities. Pad samples were extracted before and after the mini-marathon polishing runs for confocal microscopy (CM) analysis of their surface micro-texture. Compared to the CVD-coated disc, the more aggressive conventional disc produced summits that were 60 percent taller and 50 percent sharper. It also caused for contact density to be more than four times higher likely due to the many more pad fragments that it generated. Consequentially, the surface micro-texture generated by the conventional disc produced a 50 percent higher directivity and a 60 percent higher removal rate. For both discs, we found that mechanical effects were rate-limiting for tungsten removal. The conventional disc resulted in a Preston's constant that was 24 percent higher than its CVD counterpart owing to its more aggressive nature and pad surface micro-texture that it generated.

The effect of conditioner types and downforces during pad break-in on pad surface micro-texture evolution is investigated. Two substantially different discs are employed (i.e. conventional vs CVD-coated), each at two different downforces. Pad samples are extracted throughout the break-in process and their surface micro-topography and pad-wafer contact characteristics are analyzed using confocal microscopy. The two conditioning discs result in different evolution paths during break-in. In general, the conventional disc produces more pad “fragments” that get counted as taller “artificial” asperities as compared to the CVD-coated disc. In contrast, the gentle shaving action of the CVD-coated disc promotes eventual flattening of the asperity tips. Regardless of the disc type, the mean summit heights decrease and reach stable values as break-in progresses. Compared to the CVD-coated disc, the conventional disc results in higher mean summit curvature indicating sharper asperities. This work underscores the need for optimum conditioner design for attaining a steady pad surface micro-texture at a given downforce and within a reasonable break-in time.

Based on a previous work where we investigated the effect of conditioner type and downforce on the evolution of pad surface micro-texture during break-in, we have chosen certain break-in conditions to carry out subsequent blanket SiO2 wafer polishing studies. Two different conditioner discs were used in conjunction with up to two different conditioning downforces. For each disc-downforce combination, mini-marathons were run using SiO2 wafers. Prior to polishing, each pad was broken-in for 30 min with one of the conditioner-downforce combinations. The goal of this study was to polish wafers after this break-in to see how the polishing process behaved immediately after break-in. One of the discs used in this study produced similar micro-texture results at both downforces, which echoed the results seen in the mini-marathon. When comparing the different polishing results obtained from breaking-in the pad with the different discs used in this study, the coefficient of friction (COF) and SiO2 removal rate (RR) were uncorrelated in all cases. However, the use of different discs resulted in different COF and RR trends. The uncorrelated COF and RR, as well as the differing trends, were explained by pad micro-texture results (i.e. the differing amount of fractured, poorly supported pad asperity summits).