用于生物荧光检测的高灵敏CMOS双结深光电传感器设计

Design of CMOS Double Junction Photodiodes with High Sensitivity for Bio fluorescence Detection

摘要:

基于标准CMOS工艺, 可实现单结深光电二极管传感器(p+/n-well、n-well/p-sub和n+/p-sub)和双结深光电二极管传感器(p+/n-well/p-sub)。建立了双结深光电二极管传感器的光电响应数学模型, 仿真了四种结构的光敏响应。采用上华0.5μm CMOS工艺实现了p+/n-well和p+/n-well/p-sub两种结构, 传感面积为100μm×100μm。p+/n-well型结构在400nm波长, 60lux光强下光电流为1.55nA, 暗电流为13pA, p+/n-well/p-sub型结构在同等条件下光电流为2.15nA, 暗电流为11pA。测试表明, 设计的双结深光电传感器具有更高的灵敏度, 可用于微弱的生物荧光信号检测。

Abstract:

Standard CMOS process can be used to realizing photodiode sensors with single junction (p+/n-well, n-well/p-sub and n+/p-sub )and double junction (p+/n-well/p-sub) structure. In this paper, the photoelectric mathematical model was established for double junction photodiode sensor and simulations were performed on four different structures. The p+/n-well and p+/n-well/p-sub structures with the sensing area of 100μm×100μm are realized with 0.5μm CMOS process offered by Shanghua company. The experimental results indicate that, the photocurrent and the dark current of p+/n-well structure are 1.55nA and 13pA respectively at the wavelength of 400nm and light intensity of 60lux. While under the same conditions, the photocurrent and the dark current of p+/n-well/p-sub structure can reach 2.15nA and 11pA, respectively. The test results show that the proposed double junction photodiode sensor can realize higher sensitivity, and can be used for weak bio fluorescence signal detection.