Multiband Imaging CMOS Image Sensor with Multi-Storied Photodiode Structure ^†

Area of Science:

• * Solid-state Imaging Technology
• * Optoelectronics and Sensor Design

Background:

• * Conventional CMOS image sensors (CIS) typically capture only visible light (RGB) using Bayer filters, limiting their application in near-infrared (NIR) spectrum analysis.
• * Existing methods for multiband imaging often require multiple sensors or complex optical components, increasing system size and cost.

Purpose of the Study:

• * To develop an integrated CIS with a multi-storied photodiode structure capable of simultaneous RGB and NIR image capture.
• * To enhance the sensor's optical performance through optimized wiring layers and light filtering structures.

Main Methods:

• * Designed a novel multi-storied photodiode structure with two stacked photodiode (PD) arrays.
• * Integrated wiring layers between PD arrays, optimizing material and thickness for optical filtering effects.
• * Leveraged the structure to control incident light angle and act as an optical filter for the bottom PD array.

Main Results:

• * Successfully developed a CIS capable of capturing both visible RGB and invisible NIR images concurrently.
• * Demonstrated that the integrated wiring layers and structure function as an effective optical filter.
• * Achieved wide-range sensitivity enabling specific band imaging without dedicated IR pixels or external components.

Conclusions:

• * The developed multiband imaging CIS overcomes the limitations of conventional sensors by enabling simultaneous RGB and NIR capture.
• * The optimized optical filtering structure within the sensor enhances its versatility for diverse imaging applications.
• * This innovation significantly advances the potential for capturing a wider spectrum of light information in a single sensor.