Abstract
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 (C4F8/Ar, SF6/Ar and SF6/C4F8/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 SF6/C4F8/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 SF6/C4F8/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.
Highlights
Quartz has been widely used as a resonator material in micro-sensors [1,2,3] due to its excellent material properties such as its high quality factor [4,5,6,7,8,9,10], high frequency stability and inherent piezoelectric characteristics
The laser energy results in a quartz crystal denaturation at the edge of the resonant beam in laser beam machining (LBM) technology; the roughness and flatness of the etched bottom and sidewall cannot achieve the accuracy requirements of the resonator in LBM and electrochemical discharge machining (ECDM) technology, which induces an undesirable effect on the performance of quartz resonators
The quartz deep etching process was performed with a deep reactive ion etching (DRIE) system in this paper
Summary
Quartz has been widely used as a resonator material in micro-sensors [1,2,3] due to its excellent material properties such as its high quality factor [4,5,6,7,8,9,10], high frequency stability and inherent piezoelectric characteristics. A major obstacle limiting the wide use of quartz is that there exists a limited variety of suitable processing methods for producing structures with desired shapes. A few micromachining processes such as laser beam machining (LBM) [14], abrasive jet machining (AJM) [15,16] and electrochemical discharge machining (ECDM) [17,18,19,20,21] have been studied for realizing micro-structures on quartz substrate. The laser energy results in a quartz crystal denaturation at the edge of the resonant beam in LBM technology; the roughness and flatness of the etched bottom and sidewall cannot achieve the accuracy requirements of the resonator in LBM and ECDM technology, which induces an undesirable effect on the performance of quartz resonators. A deep dry etching method with inductively coupled plasma has been investigated to obtain an excepted profile [4,5,9,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
