以乾濕複合蝕刻法進行微壓力感測器微小化之研究

Abstract

本文之方向上主要是透過一種乾、濕複合蝕刻的矽晶隔膜加工技術，進一步縮小化體型微加工(buck micromachining)法製作之壓阻式壓力感測器晶方尺寸，這種複合式加工技術相較於傳統式矽濕蝕刻技術，可使得感測元件晶方尺寸縮小達57%，換言之，此複合式加工技術可於相同之矽晶面積上，生產之壓力感測元件數量為傳統濕蝕刻技術之兩倍。

技術實施方法上，將感測隔膜之製作程序分為兩階段進行，第一階段進行乾蝕刻矽加工，使用電感耦合式電漿蝕刻(inductively coupled plasma, ICP)進行深度約80%晶圓厚度之矽蝕刻；第二階段實施電化學蝕刻停止(electro-chemical etch stop, ECE)技術，將隔膜厚度加工至元件設計值，完成感測隔膜之製作。

製作完成之壓力感測元件尺寸為1080μm*1080μm*800μm，電性測試結果元件靈敏度為 0.324 mv/v/Psi，略大於有限元素法模擬之靈敏度數值約4.5%，分析可能之誤差來源應為感測元件製作之隔膜厚度略小於原設計厚度約0.3μm所導致。

In this research, silicon piezo-resistive pressure sensor were fabricated by the combining dry and wet silicon etching method. The combining etching method can reduce the pressure sensor chip size fifty-seven percent. That is to say, the combining silicon etching wafers can yield approximately two times the number of chips than typically silicon wet etched wafers. The combining silicon etching have two major process. First step, to use the inductively coupled plasma etching equipment etch about eighty percent depth of the wafer thickness. Second step, to put electro-chemical etch stop technology in used. Make sure the sensing diaphragm’s thickness were achieved the goal of the design. In this study, the chip size after sawing is 1080μm*1080μm*800μm. The sensor sensitivity is 0.324 mv/v/Psi. the sensitivity result is grater than the estimated data by finite elements method about 4.5 percents. The variation of sensitivity resulted largely from the 0.3μm difference of the diaphragm thickness.