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Sunday, February 14, 2021

#461 Engineered wafers

 In the high-end silicon device manufacturing homogenous Si wafers, commonly referred to as bulk wafers, need to be engineered further to meet specific device related requirements. Directions in which wafer engineering may proceed depends on type of device wafers will be used for and include the following solutions.

 

Denuded zone formation Term “denuded zone” refers to the very thin part of the wafer immediately adjacent to its top surface from which some excessive structural defects and/or alien elements (contaminants) are displaced into the bulk portion of the wafer by means of the gettering processes.

 

Epitaxial extension Process of epitaxial deposition allows formation of the very-thin layer of single-crystal material in such way that the crystallographic structure of the deposited film exactly reproduces crystallographic structure of the substrate, yet the film is chemically purer and if grown sufficiently thick may feature the surface that is less defective than the surface of the substrate (e.g. formation of thick SiC epilayers on SiC).

 

Strained-layer heteroepitaxy is yet another technique that is being used to engineer substrate wafer toward building into it desired characteristics which in this case is a strained top surface layer.

 

Wafer bonding is a process which permanently bonds (fuses) two wafers into a single mechanically coherent substrate without using adhesives.  This versatile technique allows formation of semiconductor substrates which are impossible to obtain using other methods.  

 

For more information regarding wafer engineering see Guide to Semiconductor Engineering (worldscientific.com)

Posted by Jerzy Ruzyllo at 05:43 PM | Semiconductors | Link



Semi1source.com/blog is a personal blog of Jerzy Ruzyllo. He is Distinguished Professor Emeritus in the Department of Electrical Engineering at Penn State University. With over forty years' experience in academic research and teaching in semiconductor engineering he has a unique perspective on the developments in this technical domain and enjoys blogging about it.




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