應用銲線與覆晶後製程之CMOS微磁通閘製作與特性分析

Fabrication and Characterization of CMOS Micro-Fluxgate with Wire-Bonding and Flip-Chip Post Process

劉育廷(Yu-Ting Liu)

指導教授 ： 呂志誠 ； 鄭振宗

國立臺北科技大學/機電學院/機電整合研究所/碩士(2011年)

摘要

本篇論文設計及製作運用CMOS製程與銲線及覆晶技術的雙磁芯微磁通閘感測器，並分析各種電性條件對元件的影響。本論文的設計擁有比傳統磁通閘更小的體積以及比平面式的微磁通閘更高的靈敏度與更低的雜訊，我們透過螺線管形狀激發線圈的設計來得到更強的激發磁場來使磁芯更容易飽和。微磁通閘晶片整體面積為2.5 mm 2.5 mm，感測元件部分為2.5 mm 1.8 mm，包含磁芯、平面感應線圈、下層激發線圈(CMOS製程的金屬鋁)、上層激發圈(鋁線)。實驗方面，我們使用激發振幅3 V(激發電流174.9 mA)、激發頻率25kHz量測2倍頻諧波的訊號，得到磁場-電壓轉移率為4.32 V/T`。而在同樣激發電流下調整激發頻率至210 kHz，磁場-電壓轉移率則增加為9.43 V/T。由此可知，我們可以透過調整電性參數來得到更靈敏的訊號。值得一提的是，我們在1 Hz下量得的雜訊已經達到1.7 nT/√Hz的等級，比起其他近期類似型式的磁通閘研究來說，已為非常突出的成果。另外為製造出更高性能及更容易量產之微磁通閘感測器，我們設計了一結合覆晶封裝技術的磁通閘晶片並探討其可行性。

關鍵字

磁通閘 ； 磁場感測器 ； CMOS ； 覆晶技術

並列摘要

This paper presents a dual-core (Vacquier-type) micro-fluxgate magnetic sensor fabricated on a silicon chip based on standard CMOS technology. The 3D design with both excitation and sensing coils winding the cores can achieve a higher responsivity and a lower noise level, but the cost in mass production would be much higher in comparison with planar design. The silicon chip is 2.5 mm 2.5 mm in dimension, and the micro-fluxgate sensor occupies the area of 2.5 mm 1.8 mm. The sensor consists of magnetic cores, planar pick-up coils, bottom excitation coils (CMOS Al interconnections) and upper excitation coils (wire-bonding Al wires). The micro-solenoid excitation coils consisting of aluminum bonding wires and CMOS metallic layers can generate out-of-phase excitation magnetic fields strong enough to saturate the two magnetic cores. It was found that the sensor’s sensitivity can be optimized and the field noise spectral density can be minimized by adjusting the excitation current as well as the excitation frequency. The responsivity at the second harmonic of 25-kHz excitation frequency is maximized to 4.32 V/T when the excitation current is 174.9 mA. The largest responsivity of 9.43 V/T occurs at the second harmonic when the excitation frequency is 210 kHz and the excitation current is 174.9 mA. The minimum field noise of our device was found to be 1.7 nT/√Hz at 1 Hz under a 20-kHz excitation. In comparison with other miniature planar fluxgates with similar dimensions reported to date, our device has a relatively low field noise spectral density. In addition, the fabrication process of a new micro-fluxgate design with flip-chip technology was also investigated and the feasibility of this scheme was evaluated.

並列關鍵字

micro fluxgate ； magnetic sensor ； CMOS ； Flip-chip

參考文獻

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