應用電感耦合型電漿蝕刻且與CMOS製程相容之微機電射頻積體電路

將以電感耦合型電漿蝕刻為主，所研發之ㄧ創新矽基板蝕刻技術(深槽技術)，應用於CMOS無線射頻積體電路中的各項元件，以檢驗其相容性與功效。實驗結果顯示，藉由深槽技術將CMOS元件底下具有損耗性的矽移除之後，其電感的品質因數大幅改善，平面波導的訊號損耗近乎為零，晶片型單極天線(monopole antenna)震盪現象更為明顯，且矽基板的訊號隔離度增加了近32dB。除了上述被動元件外，該技術進一步應用於各項主動電路，在移除矽基板後，原本操作於5.4GHz之低雜訊放大器(LNA)，其雜訊指數可因此降低0.5dB，傳輸增益增加2dB; 分散式放大器(distributed amplifier) 的雜訊指數改善0.87dB且增加1.06dB之傳輸增益；操作於4GHz之LC型電壓控制震盪器(VCO)，其相位雜訊(phase noise) 亦因此改善3dB。此外，將該技術應用於直接降頻接收機的結果，其雜訊指數共改善2dB且增加1dB的電壓增益，至於直接降頻所可能造成的直流偏移(DC-offset)影響參數，其中LO至RF端的漏流(LO to RF leakage)可因此減少近25.3dB並帶來額外的14dB LO 抑制率(LO rejection ratio)。本研究首次將矽基板損耗所造成的影響，以實際量化之結果呈現，為未來相關矽基板損耗之研究奠立基石。

關鍵字

電感耦合型電漿蝕刻；互補型金氧半；射頻積體電路；微機電；基板損耗；深槽技術

並列摘要

A novel micromachining technique, Deep Trench Technology, is invented to completely remove the lossy silicon underneath the inductors of RFICs by utilizing Inductively-Coupled Plasma etching (ICP). By means of the proposed technique, it is observed that the quality factor of inductor is impressively increased, signal attenuation of a coplanar waveguide is reduced nearly to zero, mono-pole antenna exhibits a clearer resonance phenomenon, and isolation of substrate leakage can be enhanced as much as 32 dB. In addition to the passive devices, the approach is further applied to active circuits for practical applications. For the LNA operating at 5.4GHz, the noise figure is reduced by 0.5dB with the power gain raised by 2dB; the power gain of a distributed amplifier is increased by 1.06dB at 5.8GHz with a 0.87dB noise figure reduction; phase noise of a conventional 4GHz LC VCO is improved by 3dB. For a direct-conversion receiver front-end, the total noise figure is lowered by 2dB with a 1dB voltage gain enhancement, an additional 25.3dB LO-RF isolation and an extra 14dB LO rejection enhancement. The impacts of substrate removal upon the CMOS RFIC are quantified for the first time, which has paved a way for the future study toward the deeper understanding of the substrate loss.

並列關鍵字

ICP ； CMOS ； RFIC ； MEMS ； substrate loss ； Deep Trench Technology

參考文獻

[1] L. E. Larson, R. H. Hackett, M. A. Melendes, and R. F.Lohr, "Micromachined microwave actuator (MIMAC) technology--A new tuning approach for microwave integrated circuits", in Microwave and Millimeter-Wave Monolithic Circuits Symposium, Boston, 10-11 June 1991, pp. 27-30.

[2] L. E. Larson, R. H. Hackett, and R. F. Lohr, "Microactuators for GaAs-based microwave integrated circuits", in International Conference on Solid-State Sensors and Actuators, San Francisco, 24-27 June 1991, pp. 743-746.

[3] C.Y.-C. Chang, A. A. Abidi and M. Gaitan, “Large suspended inductors on silicon and their use in a 2-um CMOS RF amplifier”, IEEE Electron Device Letters, vol.14, May, 1993.

[4] N. A. Talwalkar, C. P. Yue, and S.S. Wong, “Analysis and synthesis of on-chip spiral inductors, ” IEEE Trans. Electron Devices, vol. 52, no. 2, Feb. 2005.

[5] C. P. Yue and S. S. Wong, “Physical modeling of spiral inductors on silicon,” IEEE Trans. Electron Devices, vol. 47, no. 3, March 2000.

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應用電感耦合型電漿蝕刻且與CMOS製程相容之微機電射頻積體電路

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