Evidence of the lateral collection significance in small CMOS photodiodes

Abstract

The lateral collection capacity of small CMOS photodiodes, scanned with a point source illumination, is studied. The mathematical solution of the physical equations is compared to experimental measurements in a standard UMC 90nm technology. They show close agreement and reveal that the lateral collection through the sidewalls of the depletion region becomes a significant component of the overall photocurrent. The same conclusion is achieved through device simulations under uniform illumination using ATLAS

A Review of CMOS Photodiode Modeling and the Role of the Lateral Photoresponse

“…For the sake of obtaining an analytical solution, the same assumption as in [26] regarding the spacing of the photodiodes is made, although the authors point out that at large photodiode separation distances the neglected mobility degradation along the z = 0 plane somewhat offsets the underestimation resulting from this assumption. A general and fully analytical three-dimensional model that describes the lateral collection through the side-walls of the junction of a single CMOS photodiode operating in the visible range was developed in [45], [50]. In this case, although the continuity equation for minority carriers is solved in two dimensions, the result is then integrated to 3D in order to evaluate the behavior of the whole device.…”

Hardware/software infrastructure for ASIC commissioning and rapid system prototyping

“…To achieve a high flexibility in the extension of the structure at any point in hierarchy, the decoding of the unique identifiers is performed locally within leafs. During the selection phase, 1 Apache Subversion (SVN), a revision control system mainly used for software development. the identifier is being forwarded until the requested slave is reached.…”

“…The design of complex, mixed-signal integrated circuits, such as image sensors, often requires the implementation and evaluation of prototypes of crucial subcomponents prior to system integration. All these blocks need to be tested and characterized regarding their electrical or optical properties [1]. The commissioning of prototypes is usually a very challenging task, because both the analog and digital interfaces have to be considered.…”