Study on 3D Effects on Small Time Delay Integration Image Sensor Pixels.

Area of Science:

• Solid-state device physics
• Image sensor technology
• Semiconductor device modeling

Background:

• Traditional 2D models inadequately represent performance in small-sized Time Delay Integration (TDI) image sensor pixels.
• 3D effects significantly influence critical parameters like barrier height and full well capacity.
• Understanding these 3D effects is crucial for advancing high-performance image sensors.

Purpose of the Study:

• To investigate and quantify the impact of 3D effects on performance parameters in small-sized TDI image sensor pixels.
• To compare the accuracy of 2D versus 3D simulation models for these pixels.
• To propose optimization strategies for full well potential and anti-blooming structure operating voltage.

Main Methods:

• Construction of 2D and 3D simulation models for 3.5 μm × 3.5 μm TDI pixels with a three-phase structure and lateral anti-blooming.
• Comparative analysis of simulation results from 2D and 3D models.
• Design and fabrication of test chips (3.5 μm × 3.5 μm and 7.0 μm × 7.0 μm) using a 90 nm CCD-in-CMOS process.
• Experimental validation of simulation data through chip measurements.

Main Results:

• 3D simulation models reveal limitations of traditional 2D models for small TDI pixels.
• 3D effects were shown to influence the barrier height of the anti-blooming structure and the full well potential.
• Optimized 3.5 μm × 3.5 μm pixels achieved a full well capacity of 9 ke- with charge transfer efficiency > 0.99998.
• Measurement results closely matched simulation data.

Conclusions:

• 3D effects are critical and must be considered in the design of small-sized TDI image sensor pixels.
• The proposed optimization methods effectively enhance full well potential and anti-blooming performance.
• The validated 3D simulation approach provides a reliable tool for future image sensor design and optimization.