本文將介紹一應用於壓阻式壓力感測器之新型晶片等級封裝方式（wafer level package, WLP），主要是利用高分子矽膠材料聚二甲基矽氧烷（polydimethylsiloxane, PDMS），取代傳統的Pyrex #7740玻璃作為壓力感測器中，壓力薄膜下方空腔結構（pressure cavity）的密封材。使用聚二甲基矽氧烷作為封裝材料有許多優點，第一，聚二甲基矽氧烷表面經過氧氣電漿處理後，其親水性的表面與許多微機電製程材料，如矽、氧化矽、氮化矽等都有非常良好的鍵合效果，且其封裝過程皆為室溫製程。第二，其本身成本比其它矽質材料便宜許多。第三，其封裝製程時間僅需半小時，比起其它傳統封裝製程要來的快速。本文利用此新封裝材料與製程，製作PDMS新型封裝之壓阻式微型壓力感測器，300psi下之壓力測試結果初步驗證了輸出靈敏度與氣密性之要求。 This paper describes a novel wafer-level packaging method at room temperature for piezoresistive pressure sensors. We use polydimethylsiloxane (PDMS) to seal the wafer backside with V-grooves for pressure sensors. PDMS has several advantages in packaging herein. First, it can be bonded with many kinds of the materials (e.g., single-crystal silicon, silicon dioxide, silicon nitride, glass and another PDMS) after the hydrophilic surface treatment at room temperature. Second, it is much cheaper compared to other silicon-based materials (e.g., PDMS costs only US$100 per 1 kg for 50 times of usage on a 4 inch wafers at least). Third, the processing time is only half of hour and much shorter than other bonding processes. Based on the benefits mentioned above, we use PDMS to package the pressure cavities of the silicon pressure sensors. The newly developed pressure sensors by this new method have been tested subject to different pressure conditions.(The maximum pressure for testing is 300 psi.) The output signals of the new sensors with PDMS packaging meets the performance requirement of good sensitivity and hermetic sealing.
