“Sony Corporation announced today that it has developed a stacked direct Time of Flight (dToF) depth sensor for automotive LiDAR using single-photon avalanche diode (SPAD) pixels, an industry first.*1 This achievement was announced at the International Solid-State Circuits Conference (ISSCC), which opened on February 13, 2021.
In addition to sensing devices such as cameras and millimeter wave radar, LiDAR is becoming ever more important as a method of high-precision detection and recognition of not only road conditions but also the location and shape of objects such as vehicles and pedestrians. This trend is being driven by the popularization of advanced driver assistance systems (ADAS) and the need for this technology in autonomous driving (AD).
SPAD is a pixel structure that uses avalanche multiplication to amplify electrons from a single incident photon, causing a cascade like an avalanche, and it can detect even weak light. It is possible to accomplish long-distance, high-precision distance measuring by employing SPAD as the detector in a dToF sensor, which measures the distance to an object based on the time of flight (time difference) of a light emitted from a light source until it returns to the sensor, after being reflected by the object. Now, by leveraging Sony’s technologies such as back-illuminated pixel structure, stacked configurations and Cu-Cu connections2 cultivated in the development of CMOS image sensors, and achieving the SPAD pixels and distance measuring processing circuitry on a single chip, Sony has succeeded in developing a compact yet high-resolution sensor. This enables high-precision, high-speed measurement at 15-centimeter range resolutions up to a distance of 300 meters3. The new development will also help enable detection and recognition under severe conditions such as various temperature and weather as required for automotive equipment, thereby contributing to greater reliability for LiDAR. Achieving a single chip also helps lower the cost of LiDAR.
Sony has also developed a MEMS (Micro Electro Mechanical System)*4 LiDAR system equipped with this new technology for evaluation purposes, which is now being offered to customers and partners.”