Research On Vacuum Packaging For Room Temperature Infrared Detector

Vacuum packaging for room temperature infrared detector is an important aspect and a key technology of infrared detectors manufacture, also it is the difficult and hot point of research.The thesis focuses on vacuum packaging of room temperature infrared detector and measurement of vacuum degree after packaging.First of all, development of MEMS vacuum packaging was introduced, vacuum packaging structure and its realization were put forward. Basic bonding methods used in vacuum packaging were analyzed and compared. And ultimately adhesive bonding using non-photo conductive benzo-cyclo-butene polymer (BCB) was selected to realize vacuum packaging. BCB spin-coating thickness, BCB graphical, BCB curing temperature curve and pressure forced in bonding were studied.Secondly, in order to measure the vacuum degree of vacuum packaged MEMS devices, crystal oscillator has been used as the sensor to measure the vacuum degree. This system is based on the relationship between the impedance of tuning fork type quartz crystal resonator and the pressure. A tuning fork quartz crystal was adopt as a sensor for vacuum degree measurement, which is integrated into the internal vacuum cavity of MEMS package and is excited by a source that is composed of direct digital synthesizer(DDS). Phase and amplitude comparison circuits are used to compare the phase and amplitude of the signal from both ends of the quartz crystal and output corresponding voltage signal. Then the signal is sent to a single-chip microcomputer after A/D conversion, which can be used to measure and monitor the vacuum degree of the internal cavity of the MEMS package after processing and calibration.Through research, vacuum packaging for room temperature infrared detection array was solved. A quartz crystal oscillator vacuum gauge was designed and calibrated. The vacuum gauge can realize the scope of 2-100Pa pressure measurement, its measurement accuracy is about 10%. This system is able to meet fully automated, real-time online measurement requirements.