Dynamic, In-Situ Pressure Measurements during CMP

Abstract

A rotational setup for measuring interfacial fluid pressure and temperature was successfully constructed. Interfacial fluid measurements were performed with various slurries, slurry flow rates, and pad topographies. It was experimentally determined that the pad topography has the biggest effect in pressure and temperature distribution. This was also confirmed by tilt experiments ran in a rotational environment. For all cases, the edge high conditioned pad displayed the most changes during the experiments. For an edge high conditioned pad, the fluid pressure was found to be mostly subambient reaching levels of up to 42 kPa at the center of the fixture, and dissipating towards the edges. The pressure maps appear to be almost center symmetric. The pressure was found to be positive during the first second of contact, and rapidly turn subambient. The Subambient pressures stabilize after about 5 seconds, and their suction force was found to slow the rotating platen significantly. Suction forces were confirmed by displacement observed during the tilt experiments. The fixtures center was sucked down into the pad up to 20 m, and tends to tilt towards the leading edge. Interfacial temperatures were also found to vary with pad geometry. The edge-high conditioned pad exhibited changes of up to 4 C, concentrated at the center. The relative position and shape of these temperature rises matches the results observed in the pressure experiments. Temperature takes a longer time to reach equilibrium, up to 30 seconds in most measurements.