Optical profilometry and AFM measurements comparison on low amplitude deterministic surfaces

Surface nanotopography is important for different key advanced process steps (CMP, Bonding, Epitaxy…). However, its characterization needs data at all scales from wafer to devices. In addition in today advanced processes, roughness and deterministic topography can be of the same order impacting signal/noise ratio. No single measurement is able to measure all scales and it is crucial to develop methodologies to combine data from different instruments. This will allow to optimize control plan by using the appropriate tool at a particular scale. Optical profiler and AFM measurements are well suited to cover all if not an important range of topography scales. The study compares results from both instrument and give a methodology to identify optimal scale for them. First benefits and limitations of both technologies will be discussed in terms of resolution/throughput. In a second step and overview of most used parameters characterization with its advantage and disadvantage will be presented. Finally, data comparison will be discussed in the frame of an alternative method which it is believed to get a clearer way to address such measurements.