SPAD depth sensor for automotive LiDAR systems

Abstract

A state of the art back-illuminated (BI) single photon avalanche diode array sensor realized through a 90-nm CMOS compatible process on a 300-mm silicon platform is herein reported. The array consists of 10-µm pixels, each using a 7-µm thick silicon active layer, which enables the optical sensitivity of the device to be extended up to the near-infrared spectrum. In addition, buried metal full trench isolation is employed to suppress crosstalk. This is a critical feature in a device sensitive enough to be triggered by a single electro-luminescence photon emitted by a neighboring pixel. Finally, to maximize the fill factor and enable a BI structure, a Cu–Cu bonding process is conducted.