Wafer-level MEMS package and its reliability issues

Abstract

This paper reviews wafer-level hermetic packaging technology using anodic bonding from several reliability points of view. First, reliability risk factors of high temperature, high voltage and electrochemical O 2 generation during anodic bonding are discussed. Next, electrical interconnections through a hermetic package, i.e. electrical feedthrough, is discussed. The reliability of both hermetic sealing and electrical feedthrough must be simultaneously satisfied. A new wafer-level MEMS packaging material, anodically-bondable low temperature cofired ceramic (LTCC) wafer, is introduced, and its reliability data on hermetic sealing, electrical interconnection and flip-chip mounting on a printed circuit board (PCB) are described.

Development of wafer-level-packaging technology for simultaneous sealing of accelerometer and gyroscope under different pressures

“…Wafer-level packaging (WLP) technology is one of the most significant post-assembly processes for improvement in reliability and reduction of production size and manufacturing cost of micro-electromechanical systems (MEMS) [1][2][3]. In particular, vibratory devices such as accelerometers, gyroscopes, scanning mirrors and micro-resonators fabricated on one wafer should be packaged under the low pressure suitable for each device in order to fully exploit their performance capabilities [4][5][6][7][8][9][10][11][12][13][14][15][16]. Thus, WLP technology, which enables pressure-controlled packaging of plural devices individually, is required not only for reliability and reduction in size and cost, but also for the high performance and multi-functionality of MEMS products [17][18][19].…”

Capacitive micromachined ultrasonic transducer arrays incorporating anodically bondable low temperature co‐fired ceramic for small diameter ultrasonic endoscope

“…Anodically bondable low temperature co-fired ceramic (LTCC) with through wafer conductive via made of Au was recently developed by Tohoku University and Nikko Company, and introduced to the packaging industry [9]. Vacuum sealed cavities for packaging and printed circuit board compatibility for electronic integration of LTCC have been reported with different fabrication methods [10][11][12][13][14][15]. Silicon to borosilicate glass wafer are commonly used anodic bonding materials for CMUT fabrication [16].…”