[OPTICAL REVIEW Vol. 14, No. 3 (2007) 125-130]
© 2007 The Optical Society of Japan

32× 32 SOI CMOS Image Sensor with Pinned Photodiode on Handle Wafer

Yong-Soo CHO, H. TAKAO1, K. SAWADA1, M. ISHIDA1, and Sie-Young CHOI*

School of Electrical Engineering and Computer Science, Kyungpook National University, 1370 Sankyuk-Dong, Buk-Gu, Daegu 702-701, Republic of Korea
1Department of Electrical and Electronic Engineering, Toyohashi University of Technology, Toyohashi, Aichi 441-8580, Japan

(Received May 16, 2006; Accepted February 9, 2007)

We have fabricated a 32× 32 silicon on insulator (SOI) complementary metal oxide semiconductor (CMOS) active pixel image sensor with a pinned photodiode on a handle wafer. The structure of one pixel is a four-transistor type active pixel sensor (APS) which consists of a reset and a source follower transistor on a seed wafer, and is comprised of a photodiode, a transfer gate, and a floating diffusion on the handle wafer. The photodiode could be optimized for better quantum efficiency and low dark currents because its process on the handle wafer is independent of that of transistors on a seed wafer. Most of the wavelengths are absorbed within the visible range, because the optimized photodiode is located on the handle wafer. The image has been captured by the fabricated 32× 32 SOI CMOS image sensor with array pixels, vertical scanner, horizontal scanner, and delta-difference sampling circuit.

Key words: pinned photodiode, SOI image sensor, CMOS image sensor, APS, 4 transistor

*E-mail address: sychoi@ee.knu.ac.kr