A high deposition rate amorphous-silicon process for use as a thick sacrificial layer in surface-micromachining

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Abstract

Amorphous and polycrystalline silicon are commonly used as sacrificial layers in the surface micromachining of microelectromechanical systems (MEMS) devices, because they have high thickness uniformity over a large wafer area, and a similar coefficient of thermal expansion to suspended structural materials such as silicon nitride and silicon oxide. However, the low deposition rate of amorphous-silicon hinders its application in devices that require a suspension gap greater than several micrometres, and chemical stability can be an issue. This paper addresses these issues through the development of a high deposition rate hydrogenated amorphous silicon thin film process. We have demonstrated two unique processing regimes, which can support either a low or high temperature process. The low-temperature processes can be used to deposit silicon thin films at temperatures fromroom temperature up to 100°C, with deposition rates as high as 0.2 μm/min. The high-temperature recipes, deposited at temperatures at and above 200°C, have a slightly lower deposition rate of 0.14 μm/min, but are found to be chemically resistant to etching in positive photoresist developer.
Original languageEnglish
Pages (from-to)406-414
Number of pages9
JournalJournal of Microelectromechanical Systems
Volume26
Issue number2
DOIs
Publication statusPublished - 2017

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Surface micromachining
Deposition rates
Amorphous silicon
Temperature
Thin films
Chemical stability
Silicon oxides
Photoresists
Silicon nitride
Polysilicon
MEMS
Thermal expansion
Etching
Deposits
Silicon
Processing

Cite this

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title = "A high deposition rate amorphous-silicon process for use as a thick sacrificial layer in surface-micromachining",
abstract = "Amorphous and polycrystalline silicon are commonly used as sacrificial layers in the surface micromachining of microelectromechanical systems (MEMS) devices, because they have high thickness uniformity over a large wafer area, and a similar coefficient of thermal expansion to suspended structural materials such as silicon nitride and silicon oxide. However, the low deposition rate of amorphous-silicon hinders its application in devices that require a suspension gap greater than several micrometres, and chemical stability can be an issue. This paper addresses these issues through the development of a high deposition rate hydrogenated amorphous silicon thin film process. We have demonstrated two unique processing regimes, which can support either a low or high temperature process. The low-temperature processes can be used to deposit silicon thin films at temperatures fromroom temperature up to 100°C, with deposition rates as high as 0.2 μm/min. The high-temperature recipes, deposited at temperatures at and above 200°C, have a slightly lower deposition rate of 0.14 μm/min, but are found to be chemically resistant to etching in positive photoresist developer.",
author = "Michal Zawierta and Mariusz Martyniuk and Roger Jeffery and Gino Putrino and Adrian Keating and Buddhika Silva and Lorenzo Faraone",
year = "2017",
doi = "10.1109/JMEMS.2017.2651110",
language = "English",
volume = "26",
pages = "406--414",
journal = "Journal of Microelectromechanical Systems",
issn = "1057-7157",
publisher = "IEEE, Institute of Electrical and Electronics Engineers",
number = "2",

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TY - JOUR

T1 - A high deposition rate amorphous-silicon process for use as a thick sacrificial layer in surface-micromachining

AU - Zawierta, Michal

AU - Martyniuk, Mariusz

AU - Jeffery, Roger

AU - Putrino, Gino

AU - Keating, Adrian

AU - Silva, Buddhika

AU - Faraone, Lorenzo

PY - 2017

Y1 - 2017

N2 - Amorphous and polycrystalline silicon are commonly used as sacrificial layers in the surface micromachining of microelectromechanical systems (MEMS) devices, because they have high thickness uniformity over a large wafer area, and a similar coefficient of thermal expansion to suspended structural materials such as silicon nitride and silicon oxide. However, the low deposition rate of amorphous-silicon hinders its application in devices that require a suspension gap greater than several micrometres, and chemical stability can be an issue. This paper addresses these issues through the development of a high deposition rate hydrogenated amorphous silicon thin film process. We have demonstrated two unique processing regimes, which can support either a low or high temperature process. The low-temperature processes can be used to deposit silicon thin films at temperatures fromroom temperature up to 100°C, with deposition rates as high as 0.2 μm/min. The high-temperature recipes, deposited at temperatures at and above 200°C, have a slightly lower deposition rate of 0.14 μm/min, but are found to be chemically resistant to etching in positive photoresist developer.

AB - Amorphous and polycrystalline silicon are commonly used as sacrificial layers in the surface micromachining of microelectromechanical systems (MEMS) devices, because they have high thickness uniformity over a large wafer area, and a similar coefficient of thermal expansion to suspended structural materials such as silicon nitride and silicon oxide. However, the low deposition rate of amorphous-silicon hinders its application in devices that require a suspension gap greater than several micrometres, and chemical stability can be an issue. This paper addresses these issues through the development of a high deposition rate hydrogenated amorphous silicon thin film process. We have demonstrated two unique processing regimes, which can support either a low or high temperature process. The low-temperature processes can be used to deposit silicon thin films at temperatures fromroom temperature up to 100°C, with deposition rates as high as 0.2 μm/min. The high-temperature recipes, deposited at temperatures at and above 200°C, have a slightly lower deposition rate of 0.14 μm/min, but are found to be chemically resistant to etching in positive photoresist developer.

U2 - 10.1109/JMEMS.2017.2651110

DO - 10.1109/JMEMS.2017.2651110

M3 - Article

VL - 26

SP - 406

EP - 414

JO - Journal of Microelectromechanical Systems

JF - Journal of Microelectromechanical Systems

SN - 1057-7157

IS - 2

ER -