A 3.06 μm Single-Photon Avalanche Diode Pixel with Embedded Metal Contact and Power Grid on Deep Trench Pixel...

Area of Science:

• Photonics and Semiconductor Devices
• Image Sensor Technology
• Integrated Circuit Design

Background:

• Single-photon avalanche diodes (SPADs) are crucial for low-light imaging.
• Scaling SPAD arrays to high resolutions presents challenges in performance and power consumption.
• Edge breakdown and dark current are key limitations in SPAD pixel design.

Purpose of the Study:

• To present a novel 3.06 μm pitch SPAD pixel design.
• To improve dark count rate (DCR) and photon detection efficiency (PDE).
• To enable high-resolution photon-counting image sensors through array integration.

Main Methods:

• Implementation of an embedded metal contact and power grid within a two-step deep trench isolation.
• Optimization of the SPAD pixel's potential design for edge breakdown suppression.
• Integration of polysilicon resistors for reduced voltage drop and power consumption.

Main Results:

• Achieved a low dark count rate of 15.8 counts per second (cps).
• Demonstrated a high photon detection efficiency of 57%.
• Obtained a low crosstalk probability of 0.4% due to the embedded metal optical shield.

Conclusions:

• The presented SPAD pixel design effectively suppresses edge breakdown and reduces dark counts.
• The integrated features enhance optical shielding, reduce crosstalk, and improve PDE.
• This design is suitable for large arrays in high-resolution photon-counting image sensors, optimizing power delivery and consumption.