Surface passivation refers to a common semiconductor device fabrication process critical to modern electronics. It is the process by which a semiconductor surface such as silicon is rendered inert, and does not change semiconductor properties when it interacts with air or other materials. This is typically achieved by thermal oxidation, in which the material is heated and exposed to oxygen. In a silicon semiconductor, this process allows electricity to reliably penetrate to the conducting silicon below the surface, and to overcome the surface states that prevent electricity from reaching the semiconducting layer.[1][2] Surface passivation by thermal oxidation is one of the key features of silicon technology, and is dominant in microelectronics. The surface passivation process was developed by Mohamed M. Atalla at Bell Labs in the late 1950s.[1] It is commonly used to manufacture MOSFETs (metal-oxide-semiconductor field-effect transistors) and silicon integrated circuit chips (with the planar process), and is critical to the semiconductor industry.[1][2] Surface passivation is also critical to solar cell and carbon quantum dot technologies.
History[]

Mohamed M. Atalla developed the process of surface passivation by thermal oxidation in 1957
The surface passivation process was developed by Mohamed M. Atalla at Bell Telephone Laboratories (BTL) in the late 1950s.[1][3] In 1955, Carl Frosch and Lincoln Derick at Bell Telephone Laboratories (BTL) accidentally discovered that silicon dioxide (SiO2) could be grown on silicon. They showed that oxide layer prevented certain dopants into the silicon wafer, while allowing for others, thus discovering the passivating effect of oxidation on the semiconductor surface.[4] In the late 1950s, Atalla further discovered that the formation of a thermally grown SiO2 layer greatly reduced the concentration of electronic states at the silicon surface,[3] and discovered the important quality of SiO2 films to preserve the electrical characteristics of p–n junctions and prevent these electrical characteristics from deteriorating by the gaseous ambient environment.[5] He found that silicon oxide layers could be used to electrically stabilize silicon surfaces.[6] J.R. Ligenza and W.G. Spitzer, who studied the mechanism of thermally grown oxides, managed to fabricate a high quality Si/SiO2 stack, with Atalla and Kahng making use of their findings.[7][8][9] Atalla developed the surface passivation process, a new method of semiconductor device fabrication that involves coating a silicon wafer with an insulating layer of silicon oxide so that electricity could reliably penetrate to the conducting silicon below. By growing a layer of silicon dioxide on top of a silicon wafer, Atalla was able to overcome the surface states that prevented electricity from reaching the semiconducting layer.[1][2] For the surface passivation process, he developed the method of thermal oxidation, which was a breakthrough in silicon semiconductor technology.[10]
Before the development of integrated circuit chips, discrete diodes and transistors exhibited relatively high reverse-bias junction leakages and low breakdown voltage, caused by the large density of traps at the surface of single crystal silicon. Atalla's surface passivation process became the solution to this problem. He discovered that when a thin layer of silicon dioxide was grown on the surface of silicon where a p–n junction intercepts the surface, the leakage current of the junction was reduced by a factor from 10 to 100. This showed that the oxide reduces and stabilizes many of the interface and oxide traps. Oxide-passivation of silicon surfaces allowed diodes and transistors to be fabricated with significantly improved device characteristics, while the leakage path along the surface of the silicon was also effectively shut off. This became one of the fundamental isolation capabilities necessary for planar technology and integrated circuit chips.[11]
Atalla first published his findings in BTL memos during 1957, before presenting his work at an Electrochemical Society meeting in 1958.[12][13] The same year, he made further refinements to the process with his colleagues E. Tannenbaum and E.J. Scheibner, before they published their results in May 1959.[14][15] According to Fairchild Semiconductor engineer Chih-Tang Sah, the surface passivation process developed by Atalla's team "blazed the trail" that led to the development of the silicon integrated circuit.[11][14] Atalla's surface passivation method was the basis for several important inventions in 1959: the MOSFET (MOS transistor) by Atalla and Dawon Kahng at Bell Labs, the planar process by Jean Hoerni at Fairchild Semiconductor, and the monolithic integrated circuit chip by Robert Noyce at Fairchild in 1959.[12][13][11][14] By the mid-1960s, Atalla's process for oxidized silicon surfaces was used to fabricate virtually all integrated circuits and silicon devices.[16]
References[]
- ↑ 1.0 1.1 1.2 1.3 1.4 "Martin (John) M. Atalla". National Inventors Hall of Fame. 2009. Retrieved 21 June 2013.
- ↑ 2.0 2.1 2.2 "Dawon Kahng". National Inventors Hall of Fame. Retrieved 27 June 2019.
- ↑ 3.0 3.1 Black, Lachlan E. (2016). New Perspectives on Surface Passivation: Understanding the Si-Al2O3 Interface. Springer. p. 17. ISBN 9783319325217.
- ↑ Bassett, Ross Knox (2007). To the Digital Age: Research Labs, Start-up Companies, and the Rise of MOS Technology. Johns Hopkins University Press. pp. 22–23. ISBN 9780801886393.
- ↑ Saxena, A (2009). Invention of integrated circuits: untold important facts. International series on advances in solid state electronics and technology. World Scientific. p. 96. ISBN 9789812814456.
- ↑ Lécuyer, Christophe; Brock, David C. (2010). Makers of the Microchip: A Documentary History of Fairchild Semiconductor. MIT Press. p. 111. ISBN 9780262294324.
- ↑ Huff, Howard R.; Gösele, U.; Tsuya, H. (1998). Silicon Materials Science and Technology: Proceedings of the Eighth International Symposium on Silicon Materials Science and Technology. The Electrochemical Society. ISBN 978-1-56677-193-1.
- ↑ Lojek, Bo. (2007). History of semiconductor engineering. Berlin: Springer. ISBN 978-3-540-34258-8. OCLC 317626839.
- ↑ Morris, Peter Robin (1990). A History of the World Semiconductor Industry. IET. ISBN 978-0-86341-227-1.
- ↑ Huff, Howard (2005). High Dielectric Constant Materials: VLSI MOSFET Applications. Springer Science & Business Media. p. 34. ISBN 9783540210818.
- ↑ 11.0 11.1 11.2 Wolf, Stanley (March 1992). "A review of IC isolation technologies". Solid State Technology: 63.
- ↑ 12.0 12.1 Lojek, Bo (2007). History of Semiconductor Engineering. Springer Science & Business Media. pp. 120& 321–323. ISBN 9783540342588.
- ↑ 13.0 13.1 Bassett, Ross Knox (2007). To the Digital Age: Research Labs, Start-up Companies, and the Rise of MOS Technology. Johns Hopkins University Press. p. 46. ISBN 9780801886393.
- ↑ 14.0 14.1 14.2 Sah, Chih-Tang (October 1988). "Evolution of the MOS transistor-from conception to VLSI" (PDF). Proceedings of the IEEE. 76 (10): 1280–1326 (1290). Bibcode:1988IEEEP..76.1280S. doi:10.1109/5.16328. ISSN 0018-9219.
Those of us active in silicon material and device research during 1956–1960 considered this successful effort by the Bell Labs group led by Atalla to stabilize the silicon surface the most important and significant technology advance, which blazed the trail that led to silicon integrated circuit technology developments in the second phase and volume production in the third phase.
- ↑ Atalla, M.; Tannenbaum, E.; Scheibner, E. J. (1959). "Stabilization of silicon surfaces by thermally grown oxides". The Bell System Technical Journal. 38 (3): 749–783. doi:10.1002/j.1538-7305.1959.tb03907.x. ISSN 0005-8580.
- ↑ Donovan, R. P. (November 1966). "The Oxide-Silicon Interface". Fifth Annual Symposium on the Physics of Failure in Electronics: 199–231. doi:10.1109/IRPS.1966.362364.