Phase Difference Pixel Layout Without Light Shielding Films

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Solution Overview

Problem

Existing methods for forming focus detection pixels in solid-state imaging elements, particularly those with photoelectric conversion units on silicon layers, lack a preferable approach for achieving asymmetric sensitivity to incident light angles.

Innovation Solution

A solid-state imaging element with phase difference detection pixels, where a first photoelectric conversion unit is formed on the upper side of a semiconductor substrate and a second photoelectric conversion unit is within the substrate, utilizing a photoelectric conversion film sandwiched between upper and lower electrodes, allowing for the formation of focus detection pixels without the need for a light shielding film.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a light shielding film is formed in the vicinity of a silicon layer to increase asymmetry of sensitivity, then focus detection capability is improved, but manufacturing complexity and process steps increase

Engineering Contradiction:

Improvefocus detection capabilityVSAvoidmanufacturing process complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies asymmetry by configuring the photoelectric conversion units with different light-receiving areas. Specifically, in a pixel pair for phase difference detection, one pixel has a photoelectric conversion unit with a larger light-receiving area while the other has a smaller light-receiving area. This asymmetric configuration directly creates the required sensitivity difference for focus detection without needing additional light shielding films, thereby resolving the contradiction between detection capability and manufacturing complexity

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The patent extracts and eliminates the light shielding film component from the system. Instead of adding a light shielding film to create asymmetric sensitivity, the invention achieves the same effect by varying the light-receiving areas of the photoelectric conversion units themselves. This removes the need for additional shielding structures and simplifies the manufacturing process while maintaining focus detection functionality

Inventive Principle:

Principle #2Taking out (Extraction)

2Adaptability or versatility

If photoelectric conversion units are formed on upper side of semiconductor layer, then new imaging capabilities are enabled, but focus detection pixel formation becomes difficult

Engineering Contradiction:

Improveimaging capabilityVSAvoidfocus detection pixel formation

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent applies local quality by varying the light-receiving area of photoelectric conversion units at specific locations within the pixel pair. Rather than changing the overall structure globally, the invention locally adjusts the light-receiving areas of individual photoelectric conversion units to create asymmetric sensitivity. This localized modification enables focus detection functionality while maintaining the advanced imaging capabilities provided by the upper-side photoelectric conversion units

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

Instead of using light shielding films to create asymmetric sensitivity (the conventional approach), the patent inverts the method by using transparent structures with different light-receiving areas. Rather than blocking light in certain regions, the invention allows light to reach different areas of the photoelectric conversion units, achieving the same asymmetric sensitivity effect through a fundamentally different approach that is better suited for upper-side photoelectric conversion configurations

Inventive Principle:

Principle #13The other way round (Inversion)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables the creation of focus detection pixels with asymmetric sensitivity to incident light angles, improving autofocus functionality without increasing the number of manufacturing processes or steps.

Implementation Method 1

a first photoelectric conversion unit arranged at an upper side of a semiconductor substrate and a second photoelectric conversion unit arranged within the semiconductor substrate, wherein the first photoelectric conversion unit includes a first photoelectric conversion film

Methodology Applied

Scientific EffectPhotoelectric conversion: Photoelectric Effect

Data Source

PatentUS20240049484A1Solid-state imaging element, production method thereof, and electronic device

Publication Date: 2024.02.08 SONY GROUP CORP

AI summary

A solid-state imaging element including a phase difference detection pixel pair that includes first and second phase difference detection pixels is provided. In particular, each phase difference detection pixel of the first and second phase difference detection pixels includes a first photoelectric conversion unit arranged at an upper side of a semiconductor substrate and a second photoelectric conversion unit arranged within the semiconductor substrate. The first photoelectric conversion film may be an organic film. In addition, phase difference detection pixels may be realized without using a light shielding film.