Super-Resolution Optical Measurement for Ultra-Precision Machined Surface Defects by Using Structured Light Illumination Shift (1st report)

Demands for ultra-precision machined surface such as semiconductor wafer are rapidly growing. However, shrinking design rules of the semiconductor reduce process yield in manufacturing line. One of the biggest factors of the reduced yield is a nano-defect on the large area surface, so we must develop a defect measurement system with higher resolving power, throughput, non-destructiveness and robustness. Therefore an optical method with higher resolving power beyond the Rayleigh limit is required. In order to develop an optical inspection system with high resolving power, we have proposed the application of the structured light illumination (SLI) microscopy for the defect measurement of the ultra-precision machined surface. It is expected that the resolving power of the system exceed the Rayleigh limit by the SLI, and the robustness is enhanced by a image reconstruction algorithm using multiple images with shifts of the SLI. In the first report, to verify the resolution property of the method, we carried out theoretical examination and the computer simulation. As a result, the proposed method makes it possible to observe a structure with robustness and higher resolution beyond the Rayleigh limit and it is suggested that this method is available to measure defects on the ultra-precision machined surface.