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MEMS

Micro-electromechanical systems (MEMS) usually consist of 3D device geometries with moving elements. During processing, various thin film materials are needed inside and around the 3D parts. ALD is perfect for this application, and metals, nitrides and oxides have been used in many situations: metals for conducting layers, high-k dielectric oxides for dielectric layers of moving electrodes, hydrophobic and anti-stiction layers, wet and dry etch mask coatings, optical and dielectric layers in MEMS mirror displays, transmissive micro-optical switches (TMOS), accelerometers, pressure sensors etc.

As an excellent example, the Qualcomm Interferometric Modulator (iMoD) display is an electrostatically actuated, bistable MEMS device. The iMoD technology employs optical interference, which is an inherently efficient way to create high brightness color as no filters or polarizers are used. An iMoD element is comprised of a conductive reflective membrane (mirror) suspended over a thin film stack formed on a glass substrate. The layers in the thin film stack can be grouped in two functional subsets: conductive partially reflective stack and optical dielectric. In essence, the iMoD element is an optically resonant cavity defined by the two conductive reflectors, which are separated by an air gap and a dielectric deposited by ALD. Thus, the color seen by the viewer is associated with the resonant wavelength, determined by the optical path length between the two reflectors. The flexibility in choice of refractive index, uniform and conformal deposition, excellent adhesion, low stress and ease of scaling to production size and quantities of these thin films deposited by ALD all benefit this new display development.

ALD is suitable for many applications in Semiconductors and nanoelectronics including Gate Dielectrics, Gate Electrodes, Diffusion Barriers, and DRAM | Dynamic Random Access Memory. In the optical fields, ALD can be applied to Optical Dielectric Multilayer Structures / Filters, OLED (Organic Light Emitting Diode), Photonic Crystals and static Photonic Band Tuning, Transparent Conductors and Transparent Conducting Electrodes, TFEL or Thin Film Electroluminesence, Solar Cells, OLED Humidity Barrier, Precision Optics Coatings and Photonic Crystal Structures and Lasers. ALD is also applied to MEMS (micro electromechanical systems and Hydrophic & Anti-Stiction Layers in MEMS Devices. There are also applications of ALD in wear resistence, in coatings for blade edges and Nanocomposite Tungsten Disulphide solid lubricants. ALD is also used in nanostructures such as nanotubes & nanowires, and Atomic Force Microscope (AFM) tips. Other common applications of ALD are Catalysis & Catalyst Supports, Solid Oxide Fuel Cell Electrodes, Nano Glue, Biocompatible Coatings for medical instruments Ferromagnetic Transition Metals & Nanotubes and Internal Tube Liners and Inert Inner Linings.