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Available online at www.sciencedirect.com Sensors and Actuators A 144 (2008) 109116
 

Summary: Available online at www.sciencedirect.com
Sensors and Actuators A 144 (2008) 109116
An advanced reactive ion etching process for very high
aspect-ratio sub-micron wide trenches in silicon
Reza Abdolvand, Farrokh Ayazi
School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA 30332 USA
Received 21 March 2007; received in revised form 19 November 2007; accepted 27 December 2007
Available online 5 January 2008
Abstract
This paper reports on a practical modification of the two-step time-multiplexed plasma etching recipe (also known as the Bosch process) to
achieve high aspect-ratio sub-micron wide trenches in silicon. Mixed argon and oxygen plasma depassivation steps are introduced in between the
passivation and etching phases to promote the anisotropic removal of the passivation layer at the base of the trench. Argon does not chemically
react with polymers and silicon and removes the passivation layer only by physical sputtering. Therefore, it results in a highly anisotropic polymer
etching process. This recipe can be easily integrated on conventional ICP equipment and the scalloping on the trench sidewall can potentially
be reduced in size to less than 50 nm. To clean up all the passivation residues, a short oxygen plasma step is also added at the end of the cycle
that effectively improves the uniformity of the etching profile over various opening sizes. Excellent anisotropy of the inserted argon depassivation
step facilitates narrow trenches down to 130 nm wide and gap aspect-ratios as high as 40:1, extending the application of deep reactive ion etching
(DRIE) processes into a new broad regime.
2008 Elsevier B.V. All rights reserved.
Keywords: DRIE; Bosch process; Anisotropic etching; Passivation layer

  

Source: Ayazi, Farrokh - School of Electrical and Computer Engineering, Georgia Institute of Technology

 

Collections: Engineering