Fully Depleted, Trench-Pinned Photo Gate for CMOS Image Sensor Applications

Abstract

Tackling issues of implantation-caused defects and contamination, this paper presents a new complementary metal–oxide–semiconductor (CMOS) image sensor (CIS) pixel design concept based on a native epitaxial layer for photon detection, charge storage, and charge transfer to the sensing node. To prove this concept, a backside illumination (BSI), p-type, 2-µm-pitch pixel was designed. It integrates a vertical pinned photo gate (PPG), a buried vertical transfer gate (TG), sidewall capacitive deep trench isolation (CDTI), and backside oxide–nitride–oxide (ONO) stack. The designed pixel was fabricated with variations of key parameters for optimization. Testing results showed the following achievements: 13,000 h+ full-well capacity with no lag for charge transfer, 80% quantum efficiency (QE) at 550-nm wavelength, 5 h+/s dark current at 60 °C, 2 h+ temporal noise floor, and 75 dB dynamic range. In comparison with conventional pixel design, the proposed concept could improve CIS performance.

Single-event effects calibration using two-photon absorption and a CMOS image sensor

“…This is due to the increasing performance requirements for applications like smartphone imaging, automotive sensors, security cameras, machine vision and much more. To reduce pixel size without compromising the light sensitivity [1], new technologies where developed like backside illumination [2], microlenses on top of pixels [3] and deep trench isolation [4]. Recently a lot of R & D was invested in increasing near-infrared (NIR) quantum efficiency at 940 nm [5], driven by actively illuminated applications for 3D sensing, such as face recognition and VR/AR.…”

Process Steps for High Quality Si-Based Epitaxial Growth at Low Temperature via RPCVD

“…The epitaxial growth of silicon, silicon-germanium (SiGe) layers on a silicon substrate is a well-established technology for semiconductor fabrication, and has long been applied to the production of high-performance image sensors [1] and power devices [2]. Moreover, the addition of phosphorus or boron precursors along with the Si precursor enables the growth of Si:P or Si:B alloys with much higher P or B doping concentrations than can be obtained via ion implantation [3][4][5][6].…”