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|United States Patent||6,730,567|
|Forbes ,   et al.||May 4, 2004|
A method for forming edge-defined structures with sub-lithographic dimensions which are used to further form conduction channels and/or storage structures in memory cells. Sacrificial silicon nitride islands are deposited at low temperatures and then patterned and etched by high resolution etching techniques. Polysilicon is next deposited over the sacrificial silicon nitride islands and directionally etched to form edge-defined polysilicon dot and strip structures which are about one tenth the minimum feature size. The edge-defined polysilicon strips and dots are formed between the source and drain region of an NMOS device. Subsequent to the removal of the sacrificial silicon nitride islands, the edge-defined polysilicon strips and dots are used to mask a threshold voltage implantation in a conventional CMOS process. A conduction channel and two adjacent potential minimum dots are formed after the removal of the edge-defined polysilicon strips and dots.
|Inventors:||Forbes; Leonard (Corvallis, OR); Ahn; Kie Y. (Chappaqua, NY)|
|Assignee:||Micron Technology, Inc. (Boise, ID)|
|Filed:||March 11, 2002|
|Current U.S. Class:||438/289; 438/144; 438/734; 438/947|
|Intern'l Class:||H01L 021/336|
|Field of Search:||438/217,289,532,734,738,744,945,947,147,144,75,60|
|4419809||Dec., 1983||Riseman et al.|
|5599738||Feb., 1997||Hashemi et al.|
|5885872||Mar., 1999||Tamaki et al.||438/275.|
|5989947||Nov., 1999||Dilger et al.|
|6069380||May., 2000||Chou et al.|
|6143612||Nov., 2000||Derhacobian et al.||438/289.|
|6159620||Dec., 2000||Heath et al.|
|6362057||Mar., 2002||Taylor et al.||438/286.|
|Foreign Patent Documents|
|0 463 817||Jan., 1992||EP.|
|0 463 817||Jan., 1992||EP.|
|WO 99/66561||Dec., 1999||WO.|
Horioka, K. et al., "Highly selective and directional etchings of phosphorous doped polycrystalline silicon with tri-level resist mask employing magnetron plasma", 1998 symposium on VLSI Tecnology, Digest of Technical Papers, p. 81-2, 1998*.
Matsura et al., "Directional etchings of Si with perfect selectively to SiO.sub.2 using an ultraclean electron cyclotron resonance plasma", Applied Physics Letters, vol. 56, No. 14, p. 1339-41, 1990*.
Esashi, M. et al., "High-rate directional deep dry etching for bulk silicon micromachings", Journal of Micromechanics and Microengineering, vol. 5, No. 1, p. 5-10, 1995.
Boswell, E.C., et al., "Polysilicon field emitters", J. of Vac. Sci. and Technol. B., vol. 14, No. 3, p. 1910-13, 1996*.
Mescher M.J. et al., "A dry etch fabrication process for microelectronical devices using silicon nitride sacrificial layers", Proc. of InterPACK '97, vol. 1, p. 4358, 1997*.
Regis, J.M. et al. "Reactive ion etch of silicon nitride spacer with high selectively to oxide", Proceedings of 1997 IEEE/SEMI Advanced Semiconductor Manufacturing Conference and Workshop, p. 252-6, 1997*.
Ying Wang et al., "High-selectively silicon nitride etch process", Semiconductor International, vol. 21, No. 8, p. 235-40, 1998*.
Alkaisi, M.M. et al., "Nanolithography using wet etched nitride phase masks", Journal of Vacuum Science and Technology B, vol. 6, p. 3929-33, 1998*.
Panepucci, R.R. et al., "Silicon nitride deposited by electron cyclotron resonance plasma enhanced chemical vapor deposition for micromachining applications", Proc. Of the SPIE, vol. 3512, p. 146-51, 1998*.
Lapeyrade, M et al., "Silicon nitride films deposited by electron cyclotron resonance plasma-enhanced chemical vapor deposition", Journal of Vacuum Science and Technology A, vol. 17, No. 2, p. 433-44, 1999*.
Ono, Yukinori et al., "Fabrication Method for IC-Oriented Si Single-Electron Transistors", IEEE Transactions of Electron Devices, vol. 47, No. 1, Jan. 2000.
Takahashi et al., "Fabrication technique for Si single-electron transistor operating at room temperature", Electronics Letters, IEE Stevenage, GB, vol. 31, No. 2, Jan. 1995.
Park G., et al., "A Nano-Structure Memory with Silicon on Insulator Edge Channel and a Nano Dot", Japanese Journal of Applied Physics, vol. 37, No. 12B, Dec. 1998.