利用多晶矽於絕緣層之基底建立中心凸塊結構之壓力感測元件

Abstract

在傳統矽型壓阻式壓力感測元件，若要做接觸力感測時通常需要使用額外的封裝方式間接讓元件感應接觸力，此外在量測微小力時橫向應力不可忽略，此力導致傳統矽壓力元件在感測極微小力時線性度下滑而無法精準量測。在本篇論文將運用中心凸塊作為接觸力導引結構，可將接觸力直接施於晶片上，不需要使用特別的封裝方法即可解決感測接觸力的問題。在本論文中將由理論及有限元素分析方法推導撓度與應力，以此結果改良應變規的擺設，讓應變規間橫向應力相互抵消，增加元件對微小力的線性度。除此外中心凸塊亦可減少結構上應力集中，使結構能支撐更大的力，增加元件的量測範圍。文中將提出一簡易的覆晶封裝方法來封裝所設計的元件，此封裝方式將非常適合應用在我們所設計的微力感測元件。

A piezoresistive sensor that is capable of measurement of normal contact force, the greater linearity at small force and the larger working range is proposed in this thesis. With a circular membrane as a sensing structure and a center boss as a force-conducting structure, the proposed sensor can be fabricated as a whole without an complicated package to provide force conducting structures. By the analytic solutions for the distribution of the deflection and the longitudinal/transverse stress of the sensor, it is obtained that the massing stress was dispersed and transverse stress in the four piezoresistors was balance in this structure. It assists the sensor in increasing the linearity and the limited force. Moreover, a Flip-Chip assembly of the tactile sensor is also described in this thesis to make the sensor more reliable in a practical use.