Abstract
The conditioning process with diamond conditioners is an important role in maintaining chemical mechanical polishing (CMP) performance constant. The conditioning process maintains the surface roughness of the pad and uniformity of the pad wear, resulting in stable material removal rate (MRR) and low within wafer non-uniformity (WIWNU). The pad uniformity is greatly changed by the mechanical action in the conditioning process, and the action is controlled by three mechanical movements; pad / conditioner rotation, conditioner arm sweep. From these three motions, the pad wear profile can be obtained by accumulating the number of points in the pad mesh containing the coordinates of the diamonds moving at a specific time or distance by the movement of the diamond grit as shown in Fig. 1.
In addition, we tried to confirm the pad profile and wear amount depending on the structural properties of the conditioner, applying the diamond characteristics of the conditioner which directly causes the wear. The structural factors of conditioner that affect conditioning are pattern, pitch, size, number and shape of diamond. These factors were formulated and applied in simulation. Then, pad wear amount was calculated from the indentation depth according to the diamond characteristics, and pad profile by wear rather than profile by line density was proposed. The pad wear amount of simulation results according to the number of diamonds are shown in Fig. 2.
Finally, pad wear can be predictable according to various equipment or process conditions and it is also possible to analyze the effect of the conditioner on pad wear through this research. This work is achieved by approaching the process of conditioning in CMP from the topologic aspects and the program is developed through it. The kinematic motion of individual diamonds is modelized and simulated with structural properties of the conditioner to see how these affects the pad wear and profile.
Figure 1