Microsphere optical microscopy for immersion-free super-resolution imaging of silicon chips

Microsphere-assisted optical microscopy provides an effective super-resolution imaging technique useful in different fields. This work involves theoretical modeling and calculations including various parameters such as PNJ’s intensity, position, and the FWHM. These parameters have been experimentally verified with three different types of microspheres: polystyrene (PS), silicon dioxide (SiO 2 ), and barium titanate glass (BTG). Our work examines the effect of the materials and the effect of different sizes of microspheres, as well as the effect of the surrounding environment on the image magnification and resolution. Furthermore, an immersion-free imaging technique was proposed by attaching BTG microspheres of 30 µm diameter directly onto the front lens of the microscopy’s objective (100x/1.25). The results showed that PS microspheres provided the highest magnification, while SiO2 offered the best contrast, and the 50 µm PS microspheres showed higher magnification and focus position compared to the 5 µm and 20 µm sizes. Moreover, the imaging using BTG of 27-32 µm diameter within the newly objective lens provided 8.9x magnification, 140 nm λ/4 resolution, and an immersion-free imaging technique.