LabAdviser/Technology Research/Fabrication of Hyperbolic Metamaterials using Atomic Layer Deposition/AZO gratings: Difference between revisions

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 ====Procces flow description====
-All samples were prepared and characterized in a class 100 cleanroom. Si (100) wafers of 150 mm were used as a substrate. The main steps in the gratings manufacturing are shown in a figure below. First, the silicon trenches were realized by deep reactive ion etching (DRIE). Then, the trenches were ALD coated. After the selective removal of the top parts, the silicon core between ALD coatings was etched away during the last step. The final structure represents the highly anisotropic vertical grating. Each fabrication step was carefully evaluated using cross-sectional scanning electron microscopy (SEM) imaging.
+=====Si template fabrication=====
+The whole fabrication work took place in a class 100 cleanroom. First, standard double side polished Si (100) wafers were selected and RCA cleaned. Conventional deep-UV lithography (DUV stepper: Canon FPA-3000 EX4) was implemented for defining the grating patterns (lines 200 nm wide and 400 nm pitch) on 22 cm2 scale chips. The normal procedure includes bottom antireflective coating (BARC) and photoresist spinning, followed by spray developing. To promote adhesion and to minimize interference effects, the substrate surface was coated with a 65 nm thick BARC coating (DUV42S-6, Brewer Science, USA) followed by a bake-out at 175°C for 60 s. The positive photoresist (KRF M230Y, JSR Micro, NV) was spin-coated to a thickness of 360 nm and baked at 130°C for 90 s. Thereafter, deep reactive ion etching (DRIE) was used to fabricate trenches in the silicon substrate with a depth of 3 μm.