Solid-State Image Sensor Pixel Separation for Low Light Absorption

Solution Overview

Problem

Solid-state imaging elements face deterioration in condensing characteristics due to light absorption in conductive light blocking walls, leading to increased dark current and white spots in photoelectric conversion sections.

Innovation Solution

Incorporating a wall-like electrode with a negative bias voltage and a low absorption member in the separation region between photoelectric conversion sections, where the low absorption member is positioned further on the light incident side than the wall-like electrode, reducing light absorption and suppressing dark current and white spots.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a conductive light blocking wall is used in the separation region, then light blocking performance is improved, but light absorption increases causing deterioration in condensing characteristic

Engineering Contradiction:

Improvelight blocking performanceVSAvoidlight absorption

Core Design Contradiction:

Object-affected harmful factorsVSLoss of energy

Solution Approach 1:

The separation region is divided into two functional parts: a light blocking wall for blocking oblique light and a low absorption member for minimizing light absorption. This segmentation allows each component to perform its specific function optimally without the drawbacks of a single-material solution.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different materials are used in different locations within the separation region. The light blocking wall (made of high-refractive-index material) is positioned where light blocking is needed, while the low absorption member (made of low-absorption material) is positioned where light transmission is critical, achieving local optimization of optical properties.

Inventive Principle:

Principle #3Local quality

2Object-affected harmful factors

If a light blocking wall is positioned closer to the light incident side, then light blocking effectiveness is improved, but condensing characteristic deteriorates due to increased light absorption

Engineering Contradiction:

Improvelight blocking effectivenessVSAvoidcondensing characteristic

Core Design Contradiction:

Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The separation region is divided into two functional parts: a light blocking wall for blocking oblique light and a low absorption member for minimizing light absorption. This segmentation allows each component to perform its specific function optimally without the drawbacks of a single-material solution.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different materials are used in different locations within the separation region. The light blocking wall (made of high-refractive-index material) is positioned where light blocking is needed, while the low absorption member (made of low-absorption material) is positioned where light transmission is critical, achieving local optimization of optical properties.

Inventive Principle:

Principle #3Local quality

3Quantity of substance

If the photoelectric conversion section is made larger to improve light receiving amount, then saturation charge amount increases, but dark current and white spots increase due to larger area

Engineering Contradiction:

Improvelight receiving amountVSAvoiddark current and white spots

Core Design Contradiction:

Quantity of substanceVSObject-generated harmful factors

Solution Approach 1:

The invention converts the potentially harmful effect of the separation region into a beneficial one by using a low absorption member that not only blocks light between pixels but also acts as a light guide, directing oblique light into the photoelectric conversion section and increasing the light receiving amount without increasing dark current.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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

This configuration effectively suppresses deterioration in the condensing characteristic of photoelectric conversion sections by minimizing light absorption and reducing dark current and white spots, thereby enhancing image quality.

Implementation Method 1

a wall-like electrode and a low absorption member. The wall-like electrode is disposed in a wall shape, and a negative bias voltage is applied thereto

Methodology Applied

Scientific EffectNegative bias voltage: Electric Field

Implementation Method 2

The low absorption member is disposed further on the light incident side than the wall-like electrode and has a light absorption rate smaller than that of the wall-like electrode

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Data Source

PatentUS20240258348A1Solid-state imaging element, method of manufacturing solid-state imaging element, and electronic equipment

Publication Date: 2024.08.01 SONY SEMICON SOLUTIONS CORP

AI summary

A solid-state imaging element according to the present disclosure includes a semiconductor layer and a separation region. The semiconductor layer includes a plurality of photoelectric conversion sections disposed in a matrix. The separation region separates the photoelectric conversion sections adjacent to each other in the semiconductor layer. The separation region includes a wall-like electrode and a low absorption member. The wall-like electrode is disposed in a wall shape, and a negative bias voltage is applied thereto. The low absorption member is disposed further on the light incident side than the wall-like electrode and has a light absorption rate smaller than that of the wall-like electrode.