Hole inspection technology using Fourier imaging method

There are two kinds of critical dimension (CD) management tools; CD-SEM and Optical CD (OCD). OCD is preferable to other existing measurement tools, because of its higher throughput and lower photoresist damage. We have developed an Automated Pattern profile Management (APM) systems based on the OCD concept. For the monitoring thin line, APM detects light intensity from an optical system consisting of a polarizer and an analyzer set in a cross- Nicol configuration as a polarization fluctuation. This paper reports our development of monitoring technology for hole. In the case of hole management, APM detects light intensity from diffraction intensity fluctuation. First of all, the best conditions for hole management were designed from simulations. The best conditions were off-axis aperture and S polarizer. In our evaluation of wafers without underlayer, we obtained a good correlation with CD-SEM value. From the simulation, we consider the APM system to be very effective for shrinking hole process management of the next generation from the simulation.