Nanovision: A new paradigm for enabling fast optical inspection of nanoscale structures

The ability to detect killer defects in the Semiconductor Manufacturing Industry "in line" will require resolution below 30nm by 2005. It has been assumed that optical inspection, which has been the standard tool for such applications for almost two decades and which has enabled inspection throughputs of the order of 60 wafers per hour, cannot meet this challenge. In this paper we show that the limits of optical inspection have not been reached and that therefore existing, cost-effective, mature laser technology can still be exploited to perform fast optical inspection down to the 15nm range. This breakthrough involves the wave interrogated near-field array, a new paradigm in optical inspection that combines the resolution of near-field detection with the efficiency of far-field detection. Full-physics numerical simulations are used to show that: (1) Resonant photonic antennas can amplify the scattered signal from sub-wavelength defects by over three orders of magnitude. (2) Such antennas can also discern the composition of the defect. (3) Holographic filtering of the array's scattered signal easily locates a single defect within the scanning area of the entire array. A scaled-up experiment at microwave frequencies has been performed to prove the feasibility of this technique.