## 3 Results and Discussion  
As pattern transfer methods, three different approaches are shown in Figure 3. Figure 3a used a (RIE) process for a pattern transfer method to a Si or glass substrate. When glass is used as a substrate, the buffer layer between the PR and the substrate may not be critical since the refractive index difference between SU-8 (\(n\) = 1.59) and glass (\(n\) = 1.50) is relatively small and no significant portion of optical dose is reflected to generate parasitic patterns. On the other hand, when Si is used, reflection between SU-8 and Si (\(n\) = 3.42) would be quite significant due to its large refractive index difference, and the buffer layer design becomes very critical. SU-8 doped with Rhodamine B (RhB) dye (Sigma-Aldrich, Inc., Burlington, MA, USA) has been used because of its strong absorption of green light and high quantum efficiency. First, RhB was dissolved in cyclopentanone and mixed with SU-8 and photoacid generator, where the weight ratio of SU-8:RhB:PC was 10:0.1:1. It was spin-coated on a polished Si substrate at 2000 rpm for 40 s. After soft baking it on a hotplate at 95 \({}^{\circ}\)C for a minute, it was flood-exposed under the multiband UV light for one minute and hard baked at 160 \({}^{\circ}\)C for 10 min. The resultant thickness was approximately 2.5 \(\upmu\)m. Next, a SU-8 PR layer with a weight ratio of SU-8:Rubrene:PC of 100:0.2:2.5 was spin-coated at 4000 rpm for 40 s, followed by soft baking at 95 \({}^{\circ}\)C for a minute (Figure 3(a1)). Three-beam interference lithography was performed on a circular exposure area with a diameter of 1 cm. The cumulative intensity of the exposure energy was 0.6 W cm\({}^{-2}\) and exposed beams for 3 to 8 sec gave the total exposure dosage for 2 to 5 J cm\({}^{-2}\). When the incident beams reached the PR layer, which has very good thermal stability, the exposed areas increased in molecular weight and photochemically transformed to form insoluble products [21]. The specimen was post baked on a hot plate at 95 \({}^{\circ}\)C for a minute and cooled down to room temperature, followed by development in propylene glycol monomethyl ether acetate (PGMEA). The thickness was approximately 300-400 nm (Figure 3(a2)). RIE was performed in an oxygen-dominant environment for buffer layer patterning (Figure 3(a3)) and in a chlorine-dominant environment for Si layer patterning (Figure 3(a4)). Figure 4 shows a fabricated photonic crystal membrane at the stage depicted in Figure 3(a2). Figure 2: Large-area (1 cm\({}^{2}\)) covered nanoporous structures patterned by MIL. The three layers are clearly seen with the top layer patterned in a hexagonal symmetric shape. Figure 5 shows a pattern transferred glass substrate, where RIE has been performed in O\({}_{2}\)CF\({}_{4}\) of 15:3.5 sccm with a power of 20 W for 30 s for buffer layer etching and in O\({}_{2}\)CH\({}_{4}\) of 5:40 sccm with 70 W for 2 min for glass etching [13]. Figure 3b shows a pattern transfer process using polydimethylsiloxane (PDMS) nanomolding. After the interference lithography and RIE process with PR on the glass substrate to make nanoporous glass structures as shown in Figure 3a, PDMS was poured on the nanoporous glass surface and cured at 60 \({}^{\circ}\)C for 2 h. After cooling down to room temperature, a nanopillar array, which is the negative form of the nanopore array, was formed upon separation. Figure 6a is the top view of a perfectly ordered hexagonal symmetric nanopore array, with the inset showing a magnified oblique view. Figure 6b shows a replicated PDMS structure after nanomolding, with the inset showing a magnified view of the pillar array. The scanning electron microscopy image demonstrates good fidelity. The anodized aluminum oxide (AAO) process converts pure aluminum into aluminum oxide in a specific shape, as shown in Figure 7, when it is anodized in an acidic environment under a bias voltage. The pore size and the pitch between pores can be controlled by the magnitude of the bias voltage and the type of acids.