使用混成感測技術之微型加速計的設計與製作

Abstract

本篇論文旨在研究增進微加速感測計之感測方式與利用微機電製程技術以達大量生產之可能性。 本論文係利用美國MEMSCAP Inc.所提供之獨佔性MetalMUMPs微機電製程生產本篇論文所設計之微加速感測計。MetalMUMPs製程是近年來新興的一種微機電代工製程，其屬於MUMPs製程之一分支 ，最大特色在於將20微米厚之鎳金屬以電鍍方式導入製程以當作此製程之主結構與導電溝通橋樑。 此微加速計之長寬為1970微米×1610微米。其重要突破在於一般傳統微加速感測計均為單一種感測方式而本論文所設計的微加速計為縱向雙感測，感測方式計有電容式感測及壓阻式感測：在微加速計之兩邊採用鍍上金箔之厚鎳金屬當作梳狀形平行板電容結構，以作為電容式感測，其每一邊各有100組梳狀手指亦即200個間隔可增加電容值以達可量測範圍；利用氮化矽包覆具有壓阻性質之多晶矽以進行壓阻式感測，並加以惠斯同電橋將多晶矽之電阻改變量轉為電壓方式輸出。緊接著利用有限元素法之ANSYS軟體及MATHCAD數學軟體進行初步模擬，最後討論比較實驗數據與模擬結果。

The goal of this thesis is to increase the sensing types in a micro accelerometer and to achieve batch-fabricated utilizing a kind of MEMS fabrication technology. The micro accelerometer’s dimension is 1970μm×1610μm, and it is fabricated by the MetalMUMPs process supplied by MEMSCAP Inc., America. The most distinguishing feature in MetalMUMPs is that electroplated nickel, about 20 μm, is used as the primary structural material and electrical interconnect layer. There was only one sensing type in traditional micro accelerometers while the one proposed in this thesis has two kinds of sensing types in the sensing axis. One is capacitive sensing: Utilizing Nickel as the comb fingers in the capacitive parallel plates structure, there 100 fingers (200 gaps ) in each side to increase the capacitance. The other is piezoresistive sensing: Utilizing piezoresistive poly-silicon clad by Si3N4 as sensing the change of resistance. Furthermore, Wheatstone Bridge is substituted for change of resistance, i.e. voltage out is instead of resistance out. Besides, simulation and math tools, ANSYS & MATHCAD, are applied to simply simulate the micro accelerometers. Finally, the experimental data and simulated datat will be discussed and compared in this article.