SiGe/Si Multi-Quantum-Well Micro-Bolometer Array Design and Fabrication with Heterogeneous Integration

Abstract

The micro-bolometer is important in the field of infrared imaging, although improvements in its performance have been limited by traditional materials. SiGe/Si multi-quantum-well materials (SiGe/Si MQWs) are novelty thermal-sensitive materials with a significantly high TCR and a comparably low 1/f noise. The application of such high-performance monocrystalline films in a micro-bolometer has been limited by film integration technology. This paper reports a SiGe/Si MQWs micro-bolometer fabrication with heterogeneous integration. The integration with the SiGe/Si MQWs handle wafer and dummy read-out circuit wafer was achieved based on adhesive wafer bonding. The SiGe/Si MQWs infrared-absorption structure and thermal bridge were calculated and designed. The SiGe/Si MQWs wafer and a 320 × 240 micro-bolometer array of 40 µm pitch L-type pixels were fabricated. The test results for the average absorption efficiency were more than 90% at the wavelength of 8–14 µm. The test pixel was measured to have a thermal capacity of 1.043 × 10−9 J/K, a thermal conductivity of 1.645 × 10−7 W/K, and a thermal time constant of 7.25 ms. Furthermore, the total TCR value of the text pixel was measured as 2.91%/K with a bias voltage of 0.3 V. The SiGe/Si MQWs micro-bolometer can be widely applied in commercial fields, especially in early medical diagnosis and biological detection.

High-Performance Ge PIN Photodiodes on a 200 mm Insulator with a Resonant Cavity Structure and Monolayer Graphene Absorber for SWIR Detection

“…Commonly used SWIR optoelectronic materials including InGaAs, − HgCdTe, − PbS, − and mainstream InGaAs SWIR imaging chips have been commercially available for a long time. − However, there are some technical difficulties, such as small substrate diameter, high wafer cost, expensive chip manufacturing cost, low yield rate, and toxicity. , In addition, these SWIR chips are not compatible with the CMOS process production lines, which require a separate production line to avoid inevitable contamination. Group IV Ge (Sn) semiconductor material was regarded as one of the most promising candidates to overturn the current SWIR imaging technology due to their excellent photoelectric response in the SWIR band and compatibility with the standard CMOS process, thereby making Ge an ideal absorption layer for the high-performance SWIR photodetectors. − …”