Dark noise in a CMOS imager pixel with negative bias on transfer gate

Hirofumi Yamashita; Motohiro Maeda; Shogo Furuya; Takanori Yagami

doi:10.1117/12.876368

16 February 2011 Dark noise in a CMOS imager pixel with negative bias on transfer gate

Hirofumi Yamashita, Motohiro Maeda, Shogo Furuya, Takanori Yagami

Proceedings Volume 7875, Sensors, Cameras, and Systems for Industrial, Scientific, and Consumer Applications XII; 78750J (2011) https://doi.org/10.1117/12.876368
Event: IS&T/SPIE Electronic Imaging, 2011, San Francisco Airport, California, United States

Abstract

Negative bias on transfer gate in 4-transistor CMOS imager pixel is an efficient way to reduce dark current generated at the Si-SiO2 interface. But further lowering of negative bias increases dark current noise. In this paper, detailed cause analysis of dark current noise generated when negative bias is applied and the key technology to reduce the dark current noise are shown. The dark output level of hot pixel follows a Trap-Assisted-Tunneling (TAT) dark current electric field dependency. Device simulation shows that the generation of high electric field is attributed to the large voltage difference between the high concentration hole accumulation layer under negatively biased transfer gate and n- layer of FD edge along transfer gate. The reduction of dark current in FD is experimentally observed when the n- dopnat concentration at FD edge is decreased and when a gate insulator thickness is increased. The results show that the mechanism of the dark current increase is Gate-Induced-Leak (GIL) TAT generated by high electric field at the edge of a FD along negatively biased transfer gate. The reduction of the maximum electric filed at the FD edge by reducing FD dopant concentration is one of the key to suppress the GIL - TAT dark current.

Citation Download Citation

Hirofumi Yamashita, Motohiro Maeda, Shogo Furuya, and Takanori Yagami "Dark noise in a CMOS imager pixel with negative bias on transfer gate", Proc. SPIE 7875, Sensors, Cameras, and Systems for Industrial, Scientific, and Consumer Applications XII, 78750J (16 February 2011); https://doi.org/10.1117/12.876368

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available