Heterogeneous 3D integration of 17 μm pitch Si/SiGe quantum well bolometer arrays for infrared imaging systems

• This paper reports on the realization of 17 μm × 17 μm pitch bolometer arrays for uncooled infrared imagers. Microbolometer arrays have been available in primarily defense applications since the mid-1980s and are typically based on deposited thin films on top of CMOS wafers that are surface-machined into sensor pixels. This paper instead focuses on the heterogeneous integration of monocrystalline Si/SiGe quantum-well-based thermistor material in a CMOS-compliant process using adhesive wafer bonding. The high-quality monocrystalline thermistor material opens up for potentially lower noise compared to commercially available uncooled microbolometer arrays together with a competitive temperature coefficient of resistance (TCR). Characterized bolometers had a TCR of -2.9% K-1 in vacuum, measured thermal conductances around 5 × 10-8 W K-1 and thermal time constants between 4.9 and 8.5 ms, depending on the design. Complications in the fabrication of stress-free bolometer legs and low-noise contacts are discussed and analyzed.

Nyckelord

Adhesive wafer bonding

Heterogeneous integration

Microbolometer arrays

Temperature coefficient of resistance

Thermal conductance

Thermal time constants

Thermistor materials

Uncooled microbolometers

Infrared detectors

Infrared imaging

Semiconductor quantum wells

Temperature sensors

Thermistors

Bolometers

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)