新穎高品質因子CMOS-MEMS加速計之設計與研究

Research on Novel CMOS-MEMS Accelerometer with High Quality Factor

黃俊軒(Jyun-Syuan Huang) ； 沈志雄(Chih-Hsiung Shen) ； 陳淑容(Shu-Jung Chen)

《中華民國振動與噪音工程學會論文集》 2014 (2014/06) Pp. 183-188

摘要

傳統CMOS-MEMS加速計的設計與製作，需在質量塊設計犧牲層的孔洞，透過蝕刻液或氣體進行下方的犧牲層蝕刻。當晶片受外力作用時，質量塊結構將相對於晶片主體結構，產生慣性的假力，造成質量塊的振動及運動藉以測量加速度變化。當帶有孔洞之質量塊在高速運動下，學理上將導致較大之空氣阻尼，因此提出一新穎的結構與製作方式，在質量塊做犧牲層製程後，使用電化學沉積金屬材料來填充孔洞，將有助於降低質量塊高速運動時與空氣摩擦所產生之阻尼。藉由模擬分析比較新穎電化學填充結構與典型CMOS-MEMS加速計結構，探討阻尼降低效益以及增加Q值的效果。研究發現電化學製程填充後的結構設計，Q值大幅增加75.2%，以及使阻尼係數降低0.022 （N．m / s）。

關鍵字

加速度計 ； 品質因素 ； 振動 ； 阻尼

並列摘要

The proof mass of traditional CMOS-MEMS accelerometer is built with array of holes which is used to enable etching solution or gas to release sacrificial layer. When the chip is subjected to an external force, the proof mass moves and vibrates relative to the main structure of the chip causing by the inertia moment, which is used to sense the difference of acceleration. When the movement of accelerometer with high-speed, a holes on the proof mass will lead to high air damping. Therefore, we propose a novel structure for proof mass by an additional manufacturing technique. Using the electrochemical deposition of metal to fill the holes after the sacrificial layer process will be helpful to reduce efficiently the air damping caused by friction between the proof mass and air. By Coventorware2012 simulation software, the novel CMOS-MEMS accelerometer with electrochemical filling structure and traditional CMOS-MEMS accelerometer is compared. The result shows it is successful to reduce the damping factor and increase the Q value in this research. Base on our proposed structural design for accelerometer, the Q value is increased significantly about 75.2% and the damping coefficient is reduced to 0.022 (N．m / s).

並列關鍵字

accelerometer ； Quality Factor ； vibration ； Damping