A Ruthenium-Based Multimetal-Contact RF MEMS Switch With a Corrugated Diaphragm
A Ruthenium-Based Multimetal-Contact RF MEMS Switch With a Corrugated Diaphragm
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DOI：
10.1109/jmems.2008.2004786
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发表时间：
2008-12-01
影响因子：
2.7
通讯作者：
Oberhammer, Joachim
中科院分区：
文献类型：
--
作者：
Ke, Feixiang;Miao, Jianmin;Oberhammer, Joachim
本文提出了一种基于波纹状氧化硅/氮化硅膜片的钌金属接触RF微机电系统开关。波纹被设计成基本上减少膜中的制造引起的应力的影响，从而导致对工艺参数变化高度不敏感的设计。此外，一种新的多层金属接触的概念，包括50-nm的铬/50-nm的钌/500-nm的金/50-nm的钌结构，被引入到改善接触可靠性，通过具有硬金属表面的钌没有实质性的妥协，在接触和传输线电阻，这是由接触物理的理论分析所示，并通过测量结果证实。新型金属化叠层的接触电阻的不同的接触压力进行了研究，并比较纯金接触。研究了在不同d 0信号电流下的接触可靠性。在1.6 mA的测量电流下，Ru-Au-Ru接触具有约1亿次循环的平均寿命，而Au-Au接触仅达到2400万次循环。对于更大的信号电流，金属触点已被证明比Au-Au触点更坚固，坚固性是Au-Au触点的十倍。引入双金属氧化物后，测量的吸合电压从平面膜片的61 V显著降低到波纹膜片的36 V。在标称触点间距为5 μ m的情况下，测得的RF隔离度在4 GHz以下优于-30 dB，在15 GHz时仍为-21 dB，而完全封装的开关（包括其传输线）的插入损耗在4 GHz以下约为-0.7 dB，在15 GHz时为-2.8 dB。
This paper presents a ruthenium metal-contact RF microelectromechanical system switch based on a corrugated silicon oxide/silicon nitride diaphragm. The corrugations are designed to substantially reduce the influence of the fabrication-induced stress in the membrane, resulting in a highly insensitive design to process parameter variations. Furthermore, a novel multilayer metal-contact concept, comprising a 50-nm chromium/50-nm ruthenium/500-nm gold/50-nm ruthenium structure, is introduced to improve the contact reliability by having a hard-metal surface of ruthenium without substantial compromise in the contact and transmission-line resistances, which is shown by theoretical analysis of the contact physics and confirmed by measurement results. The contact resistance of the novel metallization stack is investigated for different contact pressures and is compared to pure-gold contacts. The contact reliability is investigated for different do signal currents. At a measurement current of 1.6 mA, the Ru-Au-Ru contacts have an average lifetime of about 100 million cycles, whereas the Au-Au contacts reach 24 million cycles only. For larger signal currents, the metal contacts have proven to be more robust over the Au-Au contacts by a factor of ten. The measured pull-in voltage is reduced significantly from 61 V for flat diaphragm to 36 V for corrugated diaphragm with the introduction of corrugation. The measured RF isolation with a nominal contact separation of 5 mu m is better than -30 dB up to 4 GHz and still -21 dB at 15 GHz, whereas the insertion loss of the fully packaged switch including its transmission line is about -0.7 dB up to 4 GHz and -2.8 dB at 15 GHz.