LabAdviser/Technology Research/Fabrication of Hyperbolic Metamaterials using Atomic Layer Deposition/AZO gratings: Difference between revisions
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The whole fabrication work took place in a class 100 cleanroom. First, standard double side polished Si (100) wafers were selected and RCA cleaned (optional). 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 2x2 cm<sup>2</sup> scale chips. The normal procedure includes a 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. | The whole fabrication work took place in a class 100 cleanroom. First, standard double side polished Si (100) wafers were selected and RCA cleaned (optional). 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 2x2 cm<sup>2</sup> scale chips. The normal procedure includes a 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. | ||
=====Deep reactive ion etching | =====Deep reactive ion etching===== | ||
Three main steps were used in the Si template fabrication: etching of the BARC layer, high anisotropic silicon etching and resist removal. The BARC etch proceeds for 1 min using 40 sccm O2 plasma with coil and platen powers of 200 and 20 W, respectively. DRIE etching (DRIE-Pegasus from SPTS) proceeds in a switched process (Bosch process) consisting of cyclic steps of etching and surface passivation, with a process pressure of 10 mTorr. The processing substrate temperature was kept at 0°C. The trench depth was controlled by adjusting the number of cycles (150 cycles corresponds to 3 μm deep trenches). The last step in Si trench fabrication is the removal of the remaining resist. It was done by using O<sub>2</sub> plasma for 2 min with a gas flow of 100 sccm. The coil and platen powers were 800 and 20 W, respectively. The shape of the produced Si-template trench structures was carefully investigated by SEM in cross-sectional mode by sacrificing some of the prepared structures. Prior to the next step (ALD deposition) the prepared template structure received additional O<sub>2</sub>/N<sub>2</sub> plasma treatment in order to remove any possible organic residuals from resist coatings and surroundings. | Three main steps were used in the Si template fabrication: etching of the BARC layer, high anisotropic silicon etching and resist removal. The BARC etch proceeds for 1 min using 40 sccm O2 plasma with coil and platen powers of 200 and 20 W, respectively. DRIE etching (DRIE-Pegasus from SPTS) proceeds in a switched process (Bosch process) consisting of cyclic steps of etching and surface passivation, with a process pressure of 10 mTorr. The processing substrate temperature was kept at 0°C. The trench depth was controlled by adjusting the number of cycles (150 cycles corresponds to 3 μm deep trenches). The last step in Si trench fabrication is the removal of the remaining resist. It was done by using O<sub>2</sub> plasma for 2 min with a gas flow of 100 sccm. The coil and platen powers were 800 and 20 W, respectively. The shape of the produced Si-template trench structures was carefully investigated by SEM in cross-sectional mode by sacrificing some of the prepared structures. Prior to the next step (ALD deposition) the prepared template structure received additional O<sub>2</sub>/N<sub>2</sub> plasma treatment in order to remove any possible organic residuals from resist coatings and surroundings. | ||