A Numerical Method of Aligning the Optical Stacks for All Pixels.

Area of Science:

• Optics and Photonics
• Semiconductor Device Physics
• Image Sensor Technology

Background:

• Performance verification of image sensors is critical for product launch and cost reduction.
• Aligning optical stacks for off-axis pixels is a time-consuming but essential step for maintaining sensor sensitivity.
• Current alignment methods present challenges in efficiency and cost-effectiveness.

Purpose of the Study:

• To introduce a novel numerical method for aligning optical stacks of off-axis pixels.
• To reduce the overall performance test time and associated production costs.
• To validate the effectiveness of the proposed numerical method through optical simulations.

Main Methods:

• A numerical method utilizing optical stack height, refractive index, and chief ray angle (CRA) to compute optimal shift distances.
• Optical simulations were performed on sub-micron backside illumination (BSI) pixels.
• The method was evaluated across various pixel pitches, microlens designs, and CRAs.

Main Results:

• The numerical method successfully optimized the alignment of optical stacks for off-axis pixels.
• Optical simulations validated the effectiveness of the proposed alignment technique.
• The method demonstrated applicability across diverse pixel architectures and optical configurations.

Conclusions:

• The proposed numerical method offers an efficient solution for optical stack alignment in image sensors.
• Implementation of this method is expected to lead to substantial reductions in testing time and manufacturing costs.
• This approach contributes to faster product development cycles in the imaging industry.