For the realization of uncooled infrared sensors on a CMOS basis there is a broad infrastructure available at Fraunhofer IMS. In a CMOS clean room certified to the automotive industry at Fraunhofer IMS, integrated CMOS readout circuits for microbolometers are being developed and manufactured.Here, the digital low-noise readout of microbolometers using 0.35 μm CMOS technology is produced on 200 mm wafers.
As a further clean room area in the infrastructure, the MST Lab&Fab of the Fraunhoer IMS is available for post-processing of the CMOS wafers and the addition of special functions or MEMS. This is where the only microbolometer process available in Germany is carried out using an in-house developed process. Moreover, the chip scale package (CSP) is developed and produced here as miniaturized and cost-optimized vacuum housing.
In addition, there are IMS infrastructure measurement laboratories with professional measuring stations on which the characterization of uncooled infrared sensors and automated test are realized on wafer level and on individual components. During the production of IR imagers, the first step after the completed post-processing takes place as an automated electro-optical test on wafer-level for a preselection. Using the chip scale package of Fraunhofer IMS it is possible to perform this test under ambient pressure and to test the result of the microbolometer and vacuum packaging process before separation and setup of the IR imagers.
This automated test step allows to measure sensitivity (responsivity), the NETD value and the number of defected pixels of the microbolometers and to examine the tightness of the chip scale package. Then, the separation of the IR imagers and their customer-specific setup is performed in the AVT (integrated circuit packaging) area of Fraunhofer IMS. Before delivering to the customer, there is a final test as delivery criterion on device level.
This is the infrastructure of the business field IR Imagers at IMS in summary
- Certified clean room according to automotive industry standards (ISO/TS-16949) for the realization of readout circuits (use of post-processing optimized Fraunhofer IMS 0.35 µm CMOS process (“L035”)
- Digital and low-noise readout of microbolometers
- Integration of additional functionality for “easy to use” concepts
- Post-processing in the MST Lab&Fab clean room; further processing of the CMOS wafers and addition of special functions or MEMS:
- Microbolometer as IR-sensitive sensor elements. Usage of the in-house developed microbolometer process (only microbolometer process in Germany)
- Chip scale packages as miniaturized and cost-optimized vacuum housing
- Anti-reflective layers (MWIR and LWIR)
- Measurement laboratory with professional measuring stations for characterization of uncooles infrared sensors
- Automated tests, in particular the electro-optical test on wafer level
- Integrated circuit packaging for IR imagers for demonstrators, prototypes and pilot production