Implications of wafer-size scale-up on frictional, thermal, and kinetic attributes of interlayer dielectric CMP process

The interlayer dielectric (ILD) chemical mechanical polishing (CMP) process was characterized using frictional forces, material removal rates, thermal measurements, and theory. Experiments were performed on a novel 200 mm tribometer in which friction force was acquired in two directions, giving a complete resolution of the force vector in the CMP process. A thermal study of the pad surface was conducted using an infrared video camera to simultaneously measure temperature changes. A Langmuir-Hinshelwood model with a reaction temperature based on a flash heating hypothesis was applied to the experimental data to evaluate the chemical and mechanical contributions during ILD CMP. The results obtained from the 200 mm tribometer were compared to those from a 100 mm tribometer. Results showed that the scale-up of the ILD process from 100 to 200 mm caused a transition from a mechanically limited regime, in which it was still possible to detect thermal effects, to a higher degree of mechanical limitation where it was no longer possible to detect thermal effects.