Parametric study of CMOS Photodetectors Computer Aided Lab CL2 Patrick Pittet, Francis Calmon, Laurent Quiquerez 3rd International Summer School on INtelligent Signal Processing for FrontIEr Research and Industry 14-25 September 2015, Hamburg, Germany

Introduction Conventional approach One photodiode per pixel CMOS image sensors are now widely used (mobile phone camera, etc …). This lab is focused on the key parameters for the design of photodiodes in a given CMOS technology. Multi-Buried junction approach

Introduction TCAD : process and device simulation tools TCAD process and device simulation tools may be used to evaluate the main characteristics of the designed photo-detection structure. (It is noted that it may be challenging to get the process parameters for CMOS commercial technologies) TCAD : process and device simulation tools Effect of Anti Reflective coating Impact generation rate in an Avalanche PhotoDiode

Introduction Advanced electronic design automation (EDA) tools for IC design (Cadence) may be used to evaluate the main electrical characteristics of the designed photo-detection structure with its FE electronics, and to implement this structure and electronics (layout with post layout capability). CMOS technology parameters electrical are provided through a design kit. Advanced electronic design automation (EDA) tools for IC design (Cadence) ® Nick Waltham Rutherford Appleton Laboratory

Introduction TCAD and EDA tools are quite complex The Lab is implemented with a Matlab based tool to cover the different aspects of the photodetector design. The Lab is organized in three levels Wavelength sensitive light to silicon interactions Parametric study of CMOS photodiode design Special focus on CMOS multi-buried junction photodetectors

Goals of the lab By the end of the lab, you should have a better understanding of typical photodiode sensitivity response curves ® AustriaMicroSystems ILD: Interlevel Dielectric oxide FOX: Field Oxide You should have also some ideas for implementation of different photodiode structures in a given CMOS design process Two photodiode structures implemented in the same CMOS process

Buried Quad junction photodetector (BQJ) Goals of the lab You should better understand the specific characteristics of multi-buried junction detectors Buried Quad junction photodetector (BQJ)

Wavelength sensitive light to silicon interactions Each level starts with a short review of the background necessary for a good understanding of the level and it is then followed by a practical training Studied parameters @ level 1 : passivation /AR layers, absorption, e/h generation rate, ... Level Background Practical study

Parametric design of CMOS photodiodes Studied parameters @ Level 2: junction depth, biasing, doping levels, temperature

Multi buried junction photodetectors Studied parameters @ level 3: Buried double and quadruple junctions spectral characteristics, signal processing, wavelength sensitive detection Background

Conclusion Thanks for your attention and see you for the LAB …