Experimental verification of super-resolution optical inspection for semiconductor defect by using standing wave illumination shift

Semiconductor design rules and process windows continue to shrink, so we face many challenges in developing new processes such as the less 100-nm design rule and the 300-mm wafer. The challenges have become more difficult, and the next generation of defect inspections is urgently needed. Optics and electron beams have been primarily used for the detection of critical defects, but both technologies have disadvantages. The optical inspection is generally not sensitive enough for defects at 100 nm or less, while the scanning electron microscopy inspection has low throughput because it takes a long time to scan 300 mm. To find a solution to these problems, we have proposed a novel optical inspection method for the critical defects on the semiconductor wafer. First, we carried out theoretical examinations and computer simulations. As a result, the proposed method makes it possible to observe a structure with robustness and higher resolution beyond the Rayleigh limit. Second, we developed an apparatus for the basic experiment and carried out the super-resolution experiment using a line and space sample. As a result, the sample structures were clearly resolved beyond the Rayleigh limit and defects on the sample surface were detected with super-resolution.