Deep Reactive Ion Etching of Z-Cut Alpha Quartz for MEMS Resonant Devices Fabrication
Quartz is widely used in microelectromechanical systems (MEMS). Especially, MEMS quartz resonators are applied to sensors and serve as sensitive elements. The capability of deep etching is a limitation for the application. Presented in this paper is a deep and high accuracy reactive ion etching meth...
| Main Authors: | , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2020-07-01
|
| Series: | Micromachines |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2072-666X/11/8/724 |
| _version_ | 1797561298484985856 |
|---|---|
| author | Bo Li Cun Li Yulong Zhao Chao Han Quanwei Zhang |
| author_facet | Bo Li Cun Li Yulong Zhao Chao Han Quanwei Zhang |
| author_sort | Bo Li |
| collection | DOAJ |
| description | Quartz is widely used in microelectromechanical systems (MEMS). Especially, MEMS quartz resonators are applied to sensors and serve as sensitive elements. The capability of deep etching is a limitation for the application. Presented in this paper is a deep and high accuracy reactive ion etching method applied to a quartz resonator etching process with a Cr mask. In order to enhance the capability of deep etching and machining accuracy, three kinds of etching gas (C<sub>4</sub>F<sub>8</sub>/Ar, SF<sub>6</sub>/Ar and SF<sub>6</sub>/C4F<sub>8</sub>/Ar), bias power, inductively coupled plasma (ICP) power and chamber pressure were studied in an industrial reactive ion etching machine (GDE C200). Results indicated that the SF<sub>6</sub>/C<sub>4</sub>F<sub>8</sub>/Ar chemistry gas is the suitable and optimal choice. Experiment results indicate that Cr (chromium) mask can obtain a higher selectivity than aluminum and titanium mask. A “sandwich” structure composed of Al layer-Cr layer-Al layer-Cr layer was proposed. The Al (aluminum) film can play the role of releasing stress and protecting gold electrodes, which can enhance the thickness of metal mask. An optimized process using SF<sub>6</sub>/C<sub>4</sub>F<sub>8</sub>/Ar plasmas showed the quartz etching rate of 450 nm/min. Meanwhile, a microchannel with a depth of 75.4 µm is fabricated, and a nearly vertical sidewall profile, smooth surface is achieved. |
| first_indexed | 2024-03-10T18:11:56Z |
| format | Article |
| id | doaj.art-4e9f88f6e945463a922f1639ddb02bfb |
| institution | Directory Open Access Journal |
| issn | 2072-666X |
| language | English |
| last_indexed | 2024-03-10T18:11:56Z |
| publishDate | 2020-07-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Micromachines |
| spelling | doaj.art-4e9f88f6e945463a922f1639ddb02bfb2023-11-20T07:59:02ZengMDPI AGMicromachines2072-666X2020-07-0111872410.3390/mi11080724Deep Reactive Ion Etching of Z-Cut Alpha Quartz for MEMS Resonant Devices FabricationBo Li0Cun Li1Yulong Zhao2Chao Han3Quanwei Zhang4State Key Laboratory for Manufacturing System Engineering, Xi’an Jiaotong University, Xi’an 710049, ChinaState Key Laboratory for Manufacturing System Engineering, Xi’an Jiaotong University, Xi’an 710049, ChinaState Key Laboratory for Manufacturing System Engineering, Xi’an Jiaotong University, Xi’an 710049, ChinaState Key Laboratory for Manufacturing System Engineering, Xi’an Jiaotong University, Xi’an 710049, ChinaState Key Laboratory for Manufacturing System Engineering, Xi’an Jiaotong University, Xi’an 710049, ChinaQuartz is widely used in microelectromechanical systems (MEMS). Especially, MEMS quartz resonators are applied to sensors and serve as sensitive elements. The capability of deep etching is a limitation for the application. Presented in this paper is a deep and high accuracy reactive ion etching method applied to a quartz resonator etching process with a Cr mask. In order to enhance the capability of deep etching and machining accuracy, three kinds of etching gas (C<sub>4</sub>F<sub>8</sub>/Ar, SF<sub>6</sub>/Ar and SF<sub>6</sub>/C4F<sub>8</sub>/Ar), bias power, inductively coupled plasma (ICP) power and chamber pressure were studied in an industrial reactive ion etching machine (GDE C200). Results indicated that the SF<sub>6</sub>/C<sub>4</sub>F<sub>8</sub>/Ar chemistry gas is the suitable and optimal choice. Experiment results indicate that Cr (chromium) mask can obtain a higher selectivity than aluminum and titanium mask. A “sandwich” structure composed of Al layer-Cr layer-Al layer-Cr layer was proposed. The Al (aluminum) film can play the role of releasing stress and protecting gold electrodes, which can enhance the thickness of metal mask. An optimized process using SF<sub>6</sub>/C<sub>4</sub>F<sub>8</sub>/Ar plasmas showed the quartz etching rate of 450 nm/min. Meanwhile, a microchannel with a depth of 75.4 µm is fabricated, and a nearly vertical sidewall profile, smooth surface is achieved.https://www.mdpi.com/2072-666X/11/8/724quartz deep etchingmachining accuracyCr maskvertical sidewallsmooth surface |
| spellingShingle | Bo Li Cun Li Yulong Zhao Chao Han Quanwei Zhang Deep Reactive Ion Etching of Z-Cut Alpha Quartz for MEMS Resonant Devices Fabrication Micromachines quartz deep etching machining accuracy Cr mask vertical sidewall smooth surface |
| title | Deep Reactive Ion Etching of Z-Cut Alpha Quartz for MEMS Resonant Devices Fabrication |
| title_full | Deep Reactive Ion Etching of Z-Cut Alpha Quartz for MEMS Resonant Devices Fabrication |
| title_fullStr | Deep Reactive Ion Etching of Z-Cut Alpha Quartz for MEMS Resonant Devices Fabrication |
| title_full_unstemmed | Deep Reactive Ion Etching of Z-Cut Alpha Quartz for MEMS Resonant Devices Fabrication |
| title_short | Deep Reactive Ion Etching of Z-Cut Alpha Quartz for MEMS Resonant Devices Fabrication |
| title_sort | deep reactive ion etching of z cut alpha quartz for mems resonant devices fabrication |
| topic | quartz deep etching machining accuracy Cr mask vertical sidewall smooth surface |
| url | https://www.mdpi.com/2072-666X/11/8/724 |
| work_keys_str_mv | AT boli deepreactiveionetchingofzcutalphaquartzformemsresonantdevicesfabrication AT cunli deepreactiveionetchingofzcutalphaquartzformemsresonantdevicesfabrication AT yulongzhao deepreactiveionetchingofzcutalphaquartzformemsresonantdevicesfabrication AT chaohan deepreactiveionetchingofzcutalphaquartzformemsresonantdevicesfabrication AT quanweizhang deepreactiveionetchingofzcutalphaquartzformemsresonantdevicesfabrication |