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Sunday, April 27, 2014

#286 Silicon and sodium

Considering sodium (Na) ubiquity, its presence in semiconductor manufacturing environment, in this case as an unwanted contaminant, should not come as a surprise. The good news is that sodium will not harm silicon as silicon is essentially impenetrable by sodium. The bad news, however, is the ease with which sodium can penetrate SiO2 when this last is formed on the Si surface in the course of thermal oxidation.


Even worst news is that Na in SiO2 can readily move around under the influence of an electric field causing severe instabilities of the device characteristics. In fact, it was due to the uncontrolled effect of sodium on transistor operation that the introduction of MOSFET into mass production was significantly delayed some 40 years ago. Not until extraordinary measures in terms of the cleanliness of process environment were implemented that the debilitating impact of sodium in semiconductor manufacturing environments was brought under control.

Posted by Jerzy Ruzyllo at 07:44 PM | Semiconductors | Link is the personal blog of Jerzy Ruzyllo. With over 35 years of experience in academic research and teaching in the area of semiconductor engineering (currently holding position of a Distinguished Professor of Electrical Engineering and Professor of Materials Science and Engineering at Penn State University), he has a unique perspective on the developments in this progress driving technical domain and enjoys blogging about it.

With over 2000 terms defined and explained, Semiconductor Glossary is the most complete reference in the field of semiconductors on the market today.

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