NOTICE: Due to a lapse in annual appropriations, most of this website is not being updated. Learn more.
Form submissions will still be accepted but will not receive responses at this time. Sections of this site for programs using non-appropriated funds (such as NVLAP) or those that are excepted from the shutdown (such as CHIPS and NVD) will continue to be updated.
An official website of the United States government
Here’s how you know
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
Cryogenic Etching of High Aspect Ratio 400 nm Pitch Silicon Gratings
Published
Author(s)
Houxun Miao, Lei Chen, Mona Mirzaeimoghri, Richard Kasica, Han Wen
Abstract
The cryogenic process and Bosch process are two widely used processes for reactive ion etching of high aspect ratio silicon structures. This paper focuses on the cryogenic deep etching of 400.0 nm pitch silicon gratings. By creating a metal hard mask on top of the polymer grating lines, the limitation on the etching depth imposed by the selectivity of resist is eliminated, which allows free tuning of all the etching parameters. At a moderate etching depth of around 3.5 μm, the etching profile is studied with respect to the ratio of the etching gases, the chamber pressure, the inductively coupled plasma (ICP) power and the radio frequency (RF) bias power. By optimizing the etching parameters, we etched a 400.0 nm pitch grating to 10.0 μm in depth, corresponding to an aspect ratio of 50, which is more than 50% beyond the nominal aspect ratio of 30 for cryogenic process. Factors limiting the achievable etching depth are discussed.
Miao, H.
, Chen, L.
, Mirzaeimoghri, M.
, Kasica, R.
and Wen, H.
(2016),
Cryogenic Etching of High Aspect Ratio 400 nm Pitch Silicon Gratings, Journal of Microelectromechanical Systems, [online], https://doi.org/10.1109/JMEMS.2016.2593339, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=918475
(Accessed October 11, 2025)