The procedure of experiment is composed of the steps of spin coating, preexposure baking, exposing, post-exposure baking, developing, and hard baking in sequence. The obtained nanostructures are measured, characterized, and analyzed with an atomic force microscopy (AFM, Veeco Dimension 3100 AFM system, Veeco Instruments Inc., Plainview, NY, USA). To obtain the LY333531 nanopatterns with high precision and consistency, the focal sphere
should be accurately focused onto the surface of the photoresist. Furthermore, the motion of the scanning stage is required to be synchronized with laser exposure for fast fabricating nanopatterns. Results and discussion Experimental results Figure 2 is a typical image of a nanopillar array fabricated in the experiments. The top surface pattern of the overall topography is displayed
as Figure 2a. The scan range is about 10 μm × 10 μm. Each nanopillar Ipatasertib nmr is located in a circular pit whose external diameter is around 950 nm. The average diameter of the nanopillar is 65 nm, which is much smaller than the size of Abbe’s limit. Figure 2b is an AFM 3D image of the nanopillar array. Figure 2c represents the cross-sectional topography along the dark line which is shown in Figure 2a, and it illustrates the flatness of the coating surface. Figure 2d, e shows more details about the typical nanopillar in the array. Figure 2d is the top view of the nanopillar which is marked by selleck compound the arrow in the nanopillar array of Figure 2a. A dark line in Figure 2d acts as the symmetry axis of the pattern. It passes through RVX-208 the apex of the nanopillar, and its corresponding cross-sectional image is illustrated in Figure 2e. With careful calibration and analysis, it is found that the diameter of the pillar is around 48 nm, which is about λ/11, much smaller than the diffraction limit
λ/2, where λ is the incident laser wavelength at about 532 nm. Figure 2 demonstrates that the nanopillar array can be manufactured to sub-diffraction limit size with our donut-shaped CW visible laser system. Figure 2 Typical image of a nanopillar array fabricated in the experiments. (a) AFM image of nanopillar array fabricated with 532-nm CW laser and (b) its corresponding 3D image. (c) Roughness of coating along the dark line in (a). (d) Enlargement of one unit and (e) its cross section marked in (a). Figure 3 shows the typical nanopillars fabricated in our experiments. The AFM images of Figure 3a, b, c show the three different nanopillars which are fabricated with the same laser power. Figure 3d,e,f is the corresponding cross-sectional information along the black lines in Figure 3a, b, c, respectively. These black lines are drawn as symmetry axis of the patterns in Figure 3a, b, c.