由於微機電系統( MEMS )製程技術之蓬勃發展，微型元件已能成功量產，矽質壓阻式壓力感測器更是微機電市場中主要的產品之ㄧ。矽質壓阻式壓力感測器的發展已逐漸成熟，而且其優異的量測精確度使得它可以更廣泛的應用於各種領域中。為了使壓力感測器可以於更嚴苛的環境下使用，經常使用矽膠保護壓力感測器薄膜以及導線，壓力必須經過矽膠才可以傳遞到薄膜表面，此ㄧ機制亦影響了壓力感測器的輸出效能。
溫度是影響壓阻式壓力感測器效能最明顯的因子。為了提升壓力感測器效能並使得訊號量測更精確，溫度及封裝效應的影響必須加以考慮。在探討溫度及封裝效應的影響導致壓力感測器輸出電壓產生變化時，利用有限單元分析來預估壓力感測器的輸出效能。本研究將針對矽質壓力感測器兩種主要的矽膠表面型態進行探討。第一種為直接在壓力感測器上填覆矽膠，矽膠表面呈現凸起狀態；第二種情況因為壓力感測器外圍多了拘束結構，矽膠表面呈現下凹情形。利用有限單元分析探討矽膠對壓力感測器的影響，並利用實驗的方式來驗證有限單元模擬結果的合理性。
為了達成提升壓力感測器效能的目的，使用有限單元參數化分析以及因子設計分析來探究幾何及材料參數改變的影響。設計參數包含矽晶片長度及厚度、薄膜長度、矽膠厚度及材料等。對於第一種填膠型態之壓力感測器模型，研究顯示較短及較厚的晶片幾何尺寸可以改善溫度及封裝效應的影響。對於第二種填膠型態模型，因為矽膠外圍多了拘束條件，使得矽膠成為影響溫度及封裝效應最顯著的因子，研究顯示只有適當矽膠厚度及材料參數可以改善溫度及封裝效應的影響，減少壓力感測器對溫度的敏感度。

Since the piezoresistive effect was discovered, the applications of piezoresistive sensors have been widely employed in mechanical signal sensing. The silicon-based pressure sensor is one of the major applications of the MEMS device. Nowadays, the silicon piezoresistive pressure sensor is a mature technology in industry and its measurement accuracy is more rigorous in many advanced applications. For the purpose of operating the piezoresistive pressure sensor in harsh environment, the silicone gel is usually adopted to protect the die surface and wire bond while allowing the pressure signal to be transmitted to the silicon diaphragm. In addition, because the major factor that affects the high performance applications of the piezoresistive pressure sensor is the temperature dependence of its pressure characteristics, therefore both the thermal and packaging effects should be taken into account to obtain better sensor accuracy. To achieve this object, a finite element method (FEM) is adopted for the sensor performance evaluation. Moreover, the thermal and pressure loadings are applied on the sensor to study the sensitivity of output signals, the packaging-induced signal variation, reduction of thermal/packaging effects, and the output signal prediction for the pressure sensors. In this study, two types of FEM models are included. In model 1, the surface of the silicone gel is convex. By comparison, the surface of silicone gel is concave in model 2. Besides FEM analysis, this study use experiment to validate FEM simulation results rationality.
Furthermore, in order to obtain a better sensor performance, the FEM parametric and factorial design analysis are performed. The design parameters include the length and thickness of silicon chip, the membrane length, the thickness and material of silicone gel, and so on. In model 1, the findings show that a reduction in the packaging-induced thermal effect can be acquired when a shorter length and thicker thickness that the silicon chip has. In model 2, a constrained condition is applied in the silicone gel peripheral. The foregoing situation makes the silicone gel become the most significant factor. The analytic result shows that a proper selection in the silicone gel’s material and thickness can greatly reduce the packaging-induced thermal effect.

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