Ion beam etching Scia Systems Coat 200

Ion beam etching (IBE) removes material from the etch target by bombardment with directed and precisely controlled ion energies. IBE is also referred to as "ion beam milling." The IBE source generates plasma from a noble gas, typically argon. A set of electrically biased grids establishes the ion beam energy and angular divergence. The ion beam strikes the substrate, removing material by physical sputtering. Ion beam etching offers directional flexibility not available in other plasma processes. While the etch rate with IBE is typically lower than for reactive ion etching (RIE), IBE offers high precision (high anisotropism) for applications that demand exacting profile control. Also, ion beam etching can be used to remove materials when RIE is ineffective. Ion beam can etch alloys and composite materials that are not compatible with RIE. A tilting and rotating substrate stage allows the angle of incidence of the ions to be adjusted. This affects sputtering yield and resulting topography. Tilting and rotating the substrate during etching can substantially improve etch profiles and avoid material redeposition. Endpoint control is available with SIMS (secondary ion mass spectroscopy) to monitor sputtered material species, allowing etching to be stopped at specific layers. Ion-beam etching has many applications, including nanomachining of magnetic transducers and MEMS devices, and trimming of surface acoustic wave (SAW) and bulk acoustic wave (BAW) filters. A newer application is the fabrication of high-performance non-volatile memory, specifically "spin transfer torque" MRAM (magnetoresistive random-access memory).

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