The fabrication of ordered molecular assemblies on conducting silicon surfaces is of considerable interest owing to its potential applications in the microelectronic industry. One goal of semiconductor fabrication is to increase the density of active elements provided on an integrated circuit. In order to accomplish this, efforts have turned to the use of self-assembling molecular structures as an alternative to, or in conjunction with various lithographic processes to form the active elements used in integrated circuits.
In addition, interest has turned to the use of organic molecules to form such active elements (e.g., memory elements) (see, e.g., U.S. Pat. Nos. 6,272,038, 6,212,093, and 6,208,553, and PCT Publication WO 01/03126) and/or to form components of certain devices (e.g., field effect transistors, gates, sensors, transducers, etc.).
Organic molecules covalently attached to silicon are very stable due to the strength of Si—O and Si—C bonds. A number of approaches exist to form a covalent link between silicon and organic molecules (Buriak and Allen (1998) J. Am. Chem. Soc., 120: 1339–1340; Bansal and Lewis (1998) J. Phys. Chem. 102: 1067–1070; Zhu et al. (1999) Langmuir 15: 8147–8154; Coulter et al. (2000) J. Vac. Sci. Technol. A 18: 1965–1970; Bourkherroub and Wayner (1999) J. Am. Chem. Soc. 121: 11513–11515; Cleland et al. (1995) Faraday Commun., 91: 4001–4003; Bateman et al. (1998) Angew. Chem. Int. Ed., 37: 2683–2685). These approaches include chemical, electrochemical and vapor deposition on a hydrogen-terminated silicon surface.
Such approaches, however, have typically involved difficult reaction conditions, have been relatively inefficient, have degraded the organic molecule(s), and/or have resulted in the production of fairly toxic materials.