Title :
A hermetic glass-silicon micropackage with high-density on-chip feedthroughs for sensors and actuators
Author :
Ziaie, Babak ; Von Arx, Jeffrey A. ; Dokmeci, Mehmet R. ; Najafi, Khalil
Author_Institution :
Center for Integrated Sensors & Circuits, Michigan Univ., Ann Arbor, MI, USA
fDate :
9/1/1996 12:00:00 AM
Abstract :
This paper describes the development of a hermetic micropackage with high-density on-chip feedthroughs for sensor and actuator applications. The packaging technique uses low-temperature (320°C) electrostatic bonding of a custom-made glass capsule (Corning 7740, 2×2×8 mm3) to fine grain polysilicon in order to form a hermetically sealed cavity. High-density on-chip multiple polysilicon feedthroughs (200 per millimeter) are used for connecting external sensors and actuators to the electronic circuitry inside the package. A high degree of planarity over feedthrough areas is obtained by using grid-shaped polysilicon feedthrough lines that are covered with phosphosilicate glass (PSG), which is subsequently reflown at 1100°C in steam for 2 h. Saline and DI water soak tests at elevated temperatures (85 and 95°C) were performed to determine the reliability of the package. Preliminary results have shown a mean time to failure (MTTF) of 284 days and 118 days at 85 and 95°C, respectively, in DI water. An Arrhenius diffusion model for moisture penetration yields an expected lifetime of 116 years at body temperature (37°C) for these packages. In vivo tests in guinea pigs and rats for periods ranging from one to two months have shown no sign of infection, inflammation, or tissue abnormality around the implanted package
Keywords :
biomedical electronics; biomedical equipment; biosensors; microactuators; microsensors; moisture; packaging; prosthetics; seals (stoppers); semiconductor device reliability; 1100 degC; 116 year; 118 day; 284 day; 320 degC; 37 degC; 85 degC; 95 degC; Arrhenius diffusion model; actuator applications; body temperature; custom-made glass capsule; feedthrough areas; hermetic glass-silicon micropackage; hermetically sealed cavity; high-density on-chip feedthroughs; implantable biomedical devices; low-temperature electrostatic bonding; mean time to failure; moisture penetration; packaging technique; planarity; reliability; sensor applications; water soak tests; Actuators; Bonding; Circuits; Electrostatics; Glass; Hermetic seals; Joining processes; Packaging; Sensor phenomena and characterization; Temperature;
Journal_Title :
Microelectromechanical Systems, Journal of