Recent Enhancements to Interline and Electron Multiplying CCD Image Sensors

Area of Science:

• Semiconductor device physics
• Image sensor technology
• Optoelectronics

Background:

• Interline and electron-multiplying charge-coupled-device (EMCCD) image sensors are crucial for various imaging applications.
• Performance limitations such as low quantum efficiency and image smear affect sensor utility.
• Gain aging in EMCCDs can degrade performance over time.

Purpose of the Study:

• To detail recent process modifications aimed at enhancing interline and EMCCD image sensor performance.
• To investigate methods for improving quantum efficiency and reducing image smear.
• To address gain aging issues in EMCCD devices.

Main Methods:

• Utilized MeV ion implantation to modify quantum efficiency and reduce smear.
• Adjusted the depth of shallow photodiode (PD) implants to lower transfer gate voltages.
• Implemented an oxide-only dielectric layer under the multiplication phase for EMCCDs.

Main Results:

• Achieved a 2× increase in quantum efficiency in the near-infrared (NIR) spectrum.
• Reduced image smear by 6 dB overall and an additional 4 dB in the blue visible spectrum.
• Lowered photodiode-to-vertical-charge-coupled-device (VCCD) transfer gate voltage by 3 V and electronic shutter voltage by 9 V.
• Eliminated gain aging in EMCCDs through a modified dielectric structure.

Conclusions:

• The described process modifications offer significant performance improvements for interline and EMCCD image sensors.
• These advancements lead to better quantum efficiency, reduced image artifacts, and improved operational stability.
• The findings contribute to the development of higher-performing image sensors for demanding applications.