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Integrating Acoustic Surface Wave and Silicon Transistor Technology

IP.com Disclosure Number: IPCOM000074245D
Original Publication Date: 1971-Apr-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Chicotka, RJ: AUTHOR [+4]

Abstract

The implementation of acoustic surface wave (ASW) networks for many applications would be made much simpler if such networks could be integrated with silicon electronic circuitry to take advantage of amplification and other operations performed by silicon electronic elements. This integration has been hampered by the lack of piezoelectricity in silicon which prevents the generation of ASW on its surface by the usual interdigital transducer techniques. A previous crude solution to the problem has been the deposition of epitaxial films of Si and (piezoelectric) AlN on different portions of a common sapphire substrate, the Si and AlN films being butted together. An interdigital structure on top of AlN film produces acoustic surface waves in the film, which are transmitted across the AlN-Si boundary.

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Integrating Acoustic Surface Wave and Silicon Transistor Technology

The implementation of acoustic surface wave (ASW) networks for many applications would be made much simpler if such networks could be integrated with silicon electronic circuitry to take advantage of amplification and other operations performed by silicon electronic elements. This integration has been hampered by the lack of piezoelectricity in silicon which prevents the generation of ASW on its surface by the usual interdigital transducer techniques. A previous crude solution to the problem has been the deposition of epitaxial films of Si and (piezoelectric) AlN on different portions of a common sapphire substrate, the Si and AlN films being butted together. An interdigital structure on top of AlN film produces acoustic surface waves in the film, which are transmitted across the AlN-Si boundary.

The described method is a much simpler and much more flexible technique for integrating the two technologies, involving the use of certain epitaxial, piezoelectric (high-electromechanical coupling constant) films directly on top of a silicon substrate. An interdigital transducer on top of the film produces ASW which are transmitted into the Si substrate surface. This is particularly useful in the usual complicated circuit patterns, as it involves only the one film step and permits use of bulk Si. "Active matching" of the transducer via the silicon is possible, increasing the gain-band-width product of th...