High-Sensitivity Pixels with a Quad-WRGB Color Filter and Spatial Deep-Trench Isolation.

Area of Science:

• * Electrical Engineering
• * Materials Science
• * Optics

Background:

• * Increasing demand for high-resolution CMOS image sensors drives pixel size reduction below 1.0 μm.
• * Pixel size reduction negatively impacts sensitivity and increases crosstalk due to worsened aspect ratios.
• * Conventional pixel designs face limitations in achieving higher sensitivity at smaller scales.

Purpose of the Study:

• * To introduce and analyze a novel high-sensitivity pixel design for sub-1.0 μm CMOS image sensors.
• * To evaluate the optical performance of a quad-WRGB color filter array (CFA) combined with spatial deep-trench isolation (S-DTI) and spatial tungsten grid (S-WG).
• * To compare the proposed design against conventional quad-Bayer CFA and standard DTI/WG techniques.

Main Methods:

• * Employed 3D optical simulations to analyze pixel performance at 1.0, 0.9, and 0.8 μm pixel pitches.
• * Conducted comparative analysis of the proposed quad-WRGB CFA against quad-Bayer CFA.
• * Assessed the effectiveness of S-DTI and S-WG compared to conventional DTI and WG.

Main Results:

• * The proposed pixel design with quad-WRGB CFA, S-DTI, and S-WG demonstrated significant sensitivity improvements.
• * Sensitivity gains reached up to 58.2% for 1.0 μm, 67.0% for 0.9 μm, and 66.3% for 0.8 μm pixels.
• * The novel design effectively mitigates sensitivity loss associated with shrinking pixel sizes.

Conclusions:

• * The integration of quad-WRGB CFA with S-DTI and S-WG is a viable strategy for enhancing sensitivity in small-pitch CMOS image sensors.
• * This approach overcomes key limitations of conventional pixel designs at sub-1.0 μm scales.
• * The developed pixel technology offers a pathway to improved image quality in next-generation mobile and high-resolution imaging applications.