利用CMOS-MEMS製程設計及製作低驅動電壓高頻開關及可變電容

本研究利用0.35μm及0.18μm CMOS-MEMS製程設計一個具備體積小、製作容易、低電壓、高性能，且可與CMOS製程相容的DC-Contact射頻微機電開關，開關作動方式是利用靜電力驅動懸臂樑，使懸臂樑尾端金屬接觸點接觸傳輸線，達到開關目的。金屬接觸點利用SiO¬2來隔離懸臂樑直流操作壓與傳輸線的高頻訊號，經由模擬可避免高頻訊號的損失。本研究也利用0.35μm CMOS-MEMS製程設計一接觸式可變電容，開關與電容元件的後製程皆可相容，並且MEMS後製程不會破壞到電路佈局區域。本研究後製程方面，結構中以鋁金屬作為懸臂樑及犧牲層材料，透過所設計的蝕刻流道，經由濕蝕刻與超臨界乾燥可完整將結構釋放。製作完成後，可經由電壓來驅動懸臂樑，但發生接觸點金屬容易氧化情況。實驗量測結果顯示，開關以探針擠壓幫助突破氧化層情況下，在頻率2.4GHz下，0.35μm CMOS-MEMS 開關Insertion Loss為-1.99dB，Isolation為-31.7dB；0.18μm CMOS-MEMS 開關Insertion Loss為-5.85dB，Isolation為-51.4dB。可變電容部份在頻率2.4GHz，電壓0-37V情況下，電容值變化從0.141pF增加到0.197pF，變化率為33%，Q值為3.65。

關鍵字

CMOS製程；微機電製程；射頻微機電；可變電容；微波開關

並列摘要

In the study, we use 0.35μm and 0.18μm CMOS-MEMS to design the DC-contact RF switch which has the advantages of small area、easy fabrication、low -voltage and high RF performance. The switch is compatible with CMOS process. The switches are actuated by electrostatic force that drove the tail of the cantilever beam contact with the transmission line. The DC and RF signal are separated by SiO2 that avoid RF signal loss. The simulation results show that SiO2 could avoid the loss of RF signal. We also use 0.35μm CMOS-MEMS to design the contact type tunable capacitor. The switches and capacitors have similar MEMS post-process. Besides, MEMS post-process will not damage the circuit layout. In the MEMS post-process, the device is based on aluminum as the cantilevers and the scarified layer. The structure is released by wet-etching and Supercritical CO2 drying. After MEMS post-process, we can drive the cantilever via applied voltage successfully but the switch contact part is easy to oxidize. In the situation that probes push contact part, the measurement results show. At 2.4GHz, the 0.35μm CMOS-MEMS switch Insertion Loss and Isolation are -1.99dB and -31.7dB, and the 0.18μm CMOS-MEMS switch Insertion Loss and Isolation are -5.85dB and -51.4dB, respectively. The tuning range of tunable capacitors is from 0.141pF to 0.197pF. Its variation is 33% and the quality factor is 3.65 at 2.4GHz and 0-37V.

並列關鍵字

CMOS-MEMS ； RF-MEMS ； Tunable Capacitors ； RF-Switch

參考文獻

[26] 國家晶片系統設計中心，“CIC eNESW 8”，2001.

[27] 黃思維，以陽極氧化及硝酸氧化技術備製金氧半元件中氧化鋁高介電常數閘極介電層及其特性之研究，博士論文，國立臺灣大學電子工程學研究所，台北，2005

[2] K.E. Petersen, “Silicon as a Mechanical Material,” Proceedings of the IEEE, vol. 70, no. 5, pp. 420–457, May 1982.

[6] C.L. Goldsmith, Z. Yao, S. Eshelman, and D. Denniston, “Performance of Low loss RF MEMS Capacitive Switches,” IEEE Microwave and Guided Wave Letters, vol. 8, no. 8, pp. 269–271, August 1998.

[8] N.E. McGruer, P.M. Zavracky, R. Morrison, S. Majumder, D. Potter, and M. Schirmer, “RF and current handling performance of electro-statically actuated microswitches,” presented at the Sensor Expo, Cleveland, OH, 1999.

國際替代計量

利用CMOS-MEMS製程設計及製作低驅動電壓高頻開關及可變電容

未授權

主題瀏覽