Electron-beam Deposition System for Nanofabrication Processes

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Micro and Nano-fabrication technologies involve multiple complex steps in an effort to fabricate miniaturized structures and devices with a high degree of reproducibility and quality. Among the steps that are essential to make a functional device, deposition of metallic thin films (gold, silver, chromium, and platinum) are central to any fabrication of micro- and nano-scale devices. An electron beam (e-beam) deposition system is an apparatus where an electron beam is produced under high vacuum environment and focused onto a metal target. The metal atoms are then ejected by the electron flux and are deposited onto a target where the micro- and nanostructures are produced. Deposition by electron beam provides a highly-controlled rate of deposition resulting in a uniform and pristine metal surface. This technology allows one to conceive and fabricate a collection of micro- and nano-features over the surface of a single 4-inch wafer. In a typical multi-step fabrication process, the electron beam deposition system is used repeatedly throughout the sequence. For example, an adhesion layer comprised of titanium or chromium is deposited onto a semiconductor surface prior to deposition of a gold layer. Devices prepared in the Western Nanofabrication Facility typically have 3 or more layers. Layer thickness depends on the role of the layer in the final device and can vary from several nanometers to hundreds of nanometers. A high-quality e-beam deposition system is therefore the key to the success of any advanced fabrication procedure at the nanoscale. The Western Nanofabrication Facility being fully compatible with 4-inch wafers, wishes to acquire an e-beam deposition system capable of processing these wafers. The present system operating in the Western Nanofabrication Facility is an open user apparatus and was produced in the 1980’s. It is one of the busiest machines in the Nanofabrication Facility. However, its electronic, pumping and safety operation are obsolete by today’s standards, which emphasizes the urgent need for a replacement. Furthermore, a new instrument would greatly improve the uniformity and purity of each prepared metal layer, which provides our researchers with advanced capabilities to explore new methods and devices at the nano-scale.