LabAdviser/Technology Research/Fabrication of Hyperbolic Metamaterials using Atomic Layer Deposition/EMT Procces flow: Difference between revisions
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The substrates for the samples were fabricated by depositing 1 μm of Si<sub>3</sub>N<sub>4</sub> (the resonator layer) on 100 mm silicon < 100 > wafers using low-pressure chemical vapor deposition. The process was carried out at 780C with ammonia (NH<sub>3</sub>) and dichlorosilane (SiH<sub>2</sub>Cl<sub>2</sub>) as reactive gases. Thickness and refractive index of the deposited silicon nitride was measured and confirmed using spectroscopic ellipsometry. The deposited Si<sub>3</sub>N<sub>4</sub> film was carefully analyzed for existence of cracks, particles and other defects using dark field optical microscopy. The best-quality wafer with Si<sub>3</sub>N<sub>4</sub> was selected and cleaved in pieces, which were used as substrates for the deposition of Al<sub>2</sub>O<sub>3</sub>/TiO<sub>2</sub> multilayers. Before inserting each substrate into the ALD reactor, it was placed on a Si carrier wafer. Therefore the Al<sub>2</sub>O<sub>3</sub>/TiO<sub>2</sub> multilayers were grown not only on the Si<sub>3</sub>N<sub>4</sub> layer but also on the dummy carrier wafer. After the ALD process was completed, the dummy was cleaved and its cross-section was characterized using scanning electron microscopy (SEM). The SEM images reveal high-quality homogeneous, conformal coatings, as seen in the examples in Figs 1. Such a method of deposited multilayers characterization turned out to be more feasible than the direct SEM characterization of multilayers on Si<sub>3</sub>N<sub>4</sub>, since the latter suffers from issues related to charge accumulation on the silicon nitride. | The substrates for the samples were fabricated by depositing 1 μm of Si<sub>3</sub>N<sub>4</sub> (the resonator layer) on 100 mm silicon < 100 > wafers using low-pressure chemical vapor deposition. The process was carried out at 780C with ammonia (NH<sub>3</sub>) and dichlorosilane (SiH<sub>2</sub>Cl<sub>2</sub>) as reactive gases. Thickness and refractive index of the deposited silicon nitride was measured and confirmed using spectroscopic ellipsometry. The deposited Si<sub>3</sub>N<sub>4</sub> film was carefully analyzed for existence of cracks, particles and other defects using dark field optical microscopy. The best-quality wafer with Si<sub>3</sub>N<sub>4</sub> was selected and cleaved in pieces, which were used as substrates for the deposition of Al<sub>2</sub>O<sub>3</sub>/TiO<sub>2</sub> multilayers. Before inserting each substrate into the ALD reactor, it was placed on a Si carrier wafer. Therefore the Al<sub>2</sub>O<sub>3</sub>/TiO<sub>2</sub> multilayers were grown not only on the Si<sub>3</sub>N<sub>4</sub> layer but also on the dummy carrier wafer. After the ALD process was completed, the dummy was cleaved and its cross-section was characterized using scanning electron microscopy (SEM). The SEM images reveal high-quality homogeneous, conformal coatings, as seen in the examples in Figs 1. Such a method of deposited multilayers characterization turned out to be more feasible than the direct SEM characterization of multilayers on Si<sub>3</sub>N<sub>4</sub>, since the latter suffers from issues related to charge accumulation on the silicon nitride. | ||
<gallery caption="" widths="1000px" heights="700px" perrow="1"> | |||
image:multilayers222.jpg| Al<sub>2</sub>O<sub>3</sub>/TiO<sub>2</sub> multilayers. | |||
</gallery> | </gallery> | ||
== Process flow == | == Process flow == | ||