An uncooled microbolometer with peak responsivity in the long wave infrared region of the electromagnetic radiation is developed at Sensonor AS. It is a 384 x 288 focal plane array with a pixel pitch of 25µm, based on monocrystalline Si/SiGe quantum wells as IR sensitive material. The high sensitivity (TCR) and low 1/f-noise are the main performance characteristics of the product. The frame rate is maximum 60Hz and the output interface is digital (LVDS). The quantum well thermistor material is transferred to the read-out integrated circuit (ROIC) by direct wafer bonding. The ROIC wafer containing the released pixels is bonded in vacuum with a silicon cap wafer, providing hermetic encapsulation at low cost. The resulting wafer stack is mounted in a standard ceramic package. In this paper the architecture of the pixels and the ROIC, the wafer packaging and the electro-optical measurement results are presented.
An uncooled microbolometer with peak responsivity in the long wave infrared region of the electromagnetic radiation is
developed at Sensonor Technologies. It is a 384 x 288 focal plane array with a pixel pitch of 25μm, based on
monocrystalline Si/SiGe quantum wells as IR sensitive material.
The high sensitivity (TCR) and low 1/f noise are the main performance characteristics of the product. The frame rate is
maximum 60Hz and the output interface is digital (LVDS).
The quantum well thermistor material is transferred to the read-out integrated circuit (ROIC) by direct wafer bonding.
The ROIC wafer containing the released pixels is bonded in vacuum with a silicon cap wafer, providing hermetic
encapsulation at low cost. The resulting wafer stack is mounted in a standard ceramic package.
In this paper the architecture of the pixels and the ROIC, the wafer packaging and the electro-optical measurement
results are presented.
Far infrared (FIR) is becoming more widely accepted within the automotive industry as a powerful sensor to detect
Vulnerable Road Users like pedestrians and bicyclist as well as animals. The main focus of FIR system development lies
in reducing the cost of their components, and this will involve optimizing all aspects of the system. Decreased pixel size,
improved 3D process integration technologies and improved manufacturing yields will produce the necessary cost
reduction on the sensor to enable high market penetration.
The improved 3D process integration allows a higher fill factor and improved transmission/absorption properties.
Together with the high Thermal Coefficient of Resistance (TCR) and low 1/f noise properties provided by
monocrystalline silicon germanium SiGe thermistor material, they lead to bolometer performances beyond those of
existing devices. The thermistor material is deposited and optimized on an IR wafer separated from the read-out
integrated circuit (ROIC) wafer. The IR wafer is transferred to the ROIC using CMOS compatible processes and
materials, utilizing a low temperature wafer bonding process. Long term vacuum sealing obtained by wafer scale
packaging enables further cost reductions and improved quality. The approach allows independent optimization of ROIC
and thermistor material processing and is compatible with existing MEMS-foundries, allowing fast time to market.
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