title: Fabrication and Performance of MEMS-Based Pressure Sensor Packages Using Patterned Ultra-Thick Photoresists.
abstract: A novel plastic packaging of a piezoresistive pressure sensor using a patterned ultra-thick photoresist is experimentally and theoretically investigated. Two pressure sensor packages of the sacrifice-replacement and dam-ring type were used in this study. The characteristics of the packaged pressure sensors were investigated by using a finite-element (FE) model and experimental measurements. The results show that the thermal signal drift of the packaged pressure sensor with a small sensing-channel opening or with a thin silicon membrane for the dam-ring approach had a high packaging induced thermal stress, leading to a high temperature coefficient of span (TCO) response of -0.19% span/°C. The results also show that the thermal signal drift of the packaged pressure sensors with a large sensing-channel opening for sacrifice-replacement approach significantly reduced packaging induced thermal stress, and hence a low TCO response of -0.065% span/°C. However, the packaged pressure sensors of both the sacrifice-replacement and dam-ring type still met the specification -0.2% span/°C of the unpackaged pressure sensor. In addition, the size of proposed packages was 4 × 4 × 1.5 mm(3) which was about seven times less than the commercialized packages. With the same packaging requirement, the proposed packaging approaches may provide an adequate solution for use in other open-cavity sensors, such as gas sensors, image sensors, and humidity sensors.
authors.affiliation: Micro-System Technology Center, Industrial Technology Research Institute. 709 Tainan, Taiwan; E-Mails:  rexchen@itri.org.tw  (L.T.C.);  jimmychang@itri.org.tw  (J.S.C.);  enoshhsu@itri.org.tw  (C.Y.H.).
authors.forename: Lung-Tai
authors.initials: LT
authors.lastname: Chen
authors.forename: Jin-Sheng
authors.initials: JS
authors.lastname: Chang
authors.forename: Chung-Yi
authors.initials: CY
authors.lastname: Hsu
authors.forename: Wood-Hi
authors.initials: WH
authors.lastname: Cheng