A Back Illuminated 10μm SPAD Pixel Array Comprising Full Trench Isolation and Cu-Cu Bonding with Over 14% PDE at 940nm

A state of the art Back Illuminated (BI) Single Photon Avalanche Diode (SPAD) array sensor realized via a 90nm CMOS compatible process on a 300 mm silicon platform is reported in the following. The array consists of 10 μm pixels, each using a 7μm thick silicon active layer, which allows to extend the device's optical sensitivity up to the Near-Infrared (NIR) spectrum. Furthermore, buried metal Full Trench Isolation (FTI) was employed to suppress crosstalk (X-talk), a critical feature in a device sensitive enough to be triggered by a single electro-luminescence photon emitted by a neighboring pixel. Finally, in order to maximize the Fill Factor (F.F) and allow a BI structure, a Cu-Cu bonding process was carried out. Through process and device design optimization, not only a Photon Detection Efficiency (PDE) greater than 14% at λ= 940nm and low timing jitter were achieved, but also the best in class Dark Count Rate (DCR) as compared to previously reported SPAD sensors. These combined features pave the way towards efficient, eye-safe and cost-effective time of flight applications.