Fabrication and characterization of back illuminated CMOS photodiode array

With the rapid development in low-cost CMOS technology, silicon photodiodes are currently recognized as promising choice for the imager core. In this research, the arrays of back illuminated photodiodes were designed, fabricated and demonstrated with CMOS imager fabrication process on silicon wafers. The main purpose of this work was to improve the contribution of these arrays on the imaging systems before committing their design on the chips. In this CMOS process, first the n-well, p-well, n+and p+ regions were simulated and fabricated by several implantation processes. The n-well region was implanted by phosphorus at an energy of 170 keV and dose of 7x10^{12}cm^{-2} to obtain a 1 um deep well. p-well was implanted with boron at energy of 70 keV and dose of lxl0^{13}cm^{-2} with a depth comparable to n-well region. An annealing for 30 minutes was then held after completion of these two implantation steps to drive-in the dopants. Phosphorus implant (45 keV, 2x10^{14} cm^{-2}) and boron implant (30 keV, 2x10^{14} cm^{-2}) were made to form n^+ and p^+ regions respectively, with a depth around 0.4 um. Some test structures were also designed during the device fabrication, to compare the sheet resistances with the simulated values of the implantation steps. The dark current, simulated for the fabrication conditions, shows a value of 1 .95pA at a reverse bias of -3V. The measured dark current, just after metallization, had a value of 15pA with same applied bias.

Name thesis:degree_name

Master of Science in Electrical Engineering - (M.S.)

Discipline thesis:degree_discipline

Electrical and Computer Engineering

Year

2006

Author dc:creator

• Banerjee, Amitra

Contributors dc:contributor

• Durgamadhab Misra
• Marek Sosnowski
• Dentcho V. Ivanov

• CMOS technology
• Back illuminated photodiodes
• Electrical and Electronics

Repository record dc:identifier

https://digitalcommons.njit.edu/theses/441

OAI identifier oai:identifier

oai:digitalcommons.njit.edu:theses-1440