Comparison between Bosch and STiGer Processes for Deep Silicon Etching

The cryogenic process is well known to etch high aspect ratio features in silicon with smooth sidewalls. A time-multiplexed cryogenic process, called STiGer, was developed in 2006 and patented. Like the Bosch process, it consists in repeating cycles composed of an isotropic etching step followed by...

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Bibliographic Details
Published in:Micromachines (Basel) 2021-10, Vol.12 (10), p.1143
Main Authors: Tillocher, Thomas, Nos, Jack, Antoun, Gaëlle, Lefaucheux, Philippe, Boufnichel, Mohamed, Dussart, Rémi
Format: Article
Language:English
Subjects:
Bosch process
Cryogenic engineering
cryogenic etching
Cryogenic temperature
Engineering Sciences
Etching
Gases
High aspect ratio
Micro and nanotechnologies
Microelectronics
Nitrogen
Oxygen plasma
Passivity
Plasma chemistry
Plasma etching
Polymers
Power supply
Silicon
Silicon wafers
STiGer process
Substrates
time-multiplexed process
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Summary:The cryogenic process is well known to etch high aspect ratio features in silicon with smooth sidewalls. A time-multiplexed cryogenic process, called STiGer, was developed in 2006 and patented. Like the Bosch process, it consists in repeating cycles composed of an isotropic etching step followed by a passivation step. If the etching step is similar for both processes, the passivation step is a SiF4/O2 plasma that efficiently deposits a SiOxFy layer on the sidewalls only if the substrate is cooled at cryogenic temperature. In this paper, it is shown that the STiGer process can achieve profiles and performances equivalent to the Bosch process. However, since sidewall passivation is achieved with polymer free plasma chemistry, less frequent chamber cleaning is necessary, which contributes to increase the throughput.
ISSN:2072-666X
2072-666X
DOI:10.3390/mi12101143