電容式壓力感測器

Abstract

微機電系統是一龐大的研究領域,因為它集合了電子與機械兩大主題.其 中,以用IC技術製造、利用薄膜受壓力而發生機械形變以產生電訊號的壓 力感測器為此領域中最典型的代表.本論文即是以電容式壓力感測器為研 究主題,以期能藉此進入微機電系統的領域.電容式壓力感測器可看做是一 平行板電容器,其中的一邊是很薄的膜,會隨壓力的大小而作出不同程度的 形變,因此,改變了電容值的大小.所以藉由電容值的改變量,可以量出所受 的壓力值.由於它的元件結構不同於一般IC元件,所以在製造的方式上,也 有別於傳統的IC技術,例如：KOH蝕刻技術,P+薄膜形成,陽極結合技術等. 這些都將在本論文中,作一廣泛的討論.最後,為了能對此領域有更廣泛的 了解,在第二章中,也約略介紹了矽材料感測器和微機電領域的一些特殊製 程及考量. Micro-electro-mechanical systems( MEMS ) is a large field of study, because it combines two major subjects, i.e., electronic and mechanical engineering. Fabricated by IC technologies, emp- loying diaphragm deformed by pressure to generate electrical si- gnal, pressure sensor is the most representative device in this topic. This thesis thus majors in the capacitive pressure sensor in order to get into the field of MEMS. Capacitive pressure sensor can be considered as the parallel plates capacitor. One of the plates is a very thin diaphragm, so it would be deformed as pressure varying and the capacitance wo- uld be changed. Therefore, we can obtain the pressure value by the altering value of the capacitance. Because the structure of the pressure sensor device differs from the traditional IC's devices, the ways of fabricating pressure sensor are also diff- erent from traditional IC's technologies, such as KOH etching, P+ diaphragm formation, anodic bonding technique etc. These all will be extensively discussed in this thesis. At last, we generally introduce the silicon sensors and some special fabricating processes or thinkings about micromachining field in order to understand this topic extensively.