Stacked Image Sensor Oxide Film for Stable Charge Transfer

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Solution Overview

Problem

Japanese Patent Laid-Open No. 2016-063165 describes image pickup elements with oxide semiconductor layers, but oxygen loss on the surface of these layers leads to degraded charge transfer characteristics, affecting image quality.

Innovation Solution

An image pickup element with a photoelectric conversion section including a first electrode, a photoelectric conversion layer, and a second electrode, where an oxide film and an oxide semiconductor layer are formed below the photoelectric conversion layer, optimizing energy levels to enhance charge transfer by forming an oxide film on the oxide semiconductor layer to prevent oxygen deficiency and stabilize energy levels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an oxide semiconductor layer is used in the image pickup element, then photoelectric conversion efficiency is improved, but oxygen loss on the surface leads to degraded charge transfer characteristics

Engineering Contradiction:

Improvecharge transfer characteristicsVSAvoidoxygen loss

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The patent applies preliminary anti-action by forming a protective oxide film on the oxide semiconductor layer surface before oxygen loss can occur. This preventive measure counteracts the harmful effect of oxygen loss by establishing a stable oxide layer that maintains charge transfer characteristics throughout the device operation.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The patent converts the harmful oxygen loss into a beneficial protective oxide film. Instead of preventing oxide formation entirely, the invention allows controlled oxidation to create a stable surface layer that actually protects the underlying oxide semiconductor from further degradation and maintains reliable charge transfer.

Inventive Principle:

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

2Reliability

If a protective oxide film is formed on the oxide semiconductor layer, then charge transfer efficiency is improved, but device structure complexity increases

Engineering Contradiction:

Improvecharge transfer efficiencyVSAvoidlayer structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the protective oxide film formation with the existing oxide semiconductor layer deposition process. By forming the protective oxide film in-situ or as an integrated step in the manufacturing process, the design adds minimal structural complexity while achieving the desired charge transfer efficiency improvement.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent optimizes the thickness and composition parameters of the oxide film to achieve effective charge transfer protection with minimal added complexity. By carefully controlling film thickness within specific ranges and selecting appropriate oxide materials, the invention balances protective functionality with structural simplicity.

Inventive Principle:

Principle #35Parameter changes

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 improves charge storage and transfer efficiency, preventing image quality degradation and ensuring reliable migration of charge from the photoelectric conversion layer to the oxide semiconductor layer, thus enhancing the quality of captured images.

Implementation Method 1

a photoelectric conversion layer (light receiving layer) is sandwiched between two electrodes. The stacked image pickup element requires a structure for storing and transferring signal charge generated in the photoelectric conversion layer on the basis of photoelectric conversion.

Methodology Applied

Scientific EffectPhotoelectric conversion: Photovoltaic Effect

Implementation Method 2

an oxide film and an oxide semiconductor layer are formed immediately below the photoelectric conversion layer from the photoelectric conversion layer side... optimizing energy levels to enhance charge transfer by forming an oxide film on the oxide semiconductor layer to prevent oxygen deficiency and stabilize energy levels

Methodology Applied

Scientific EffectCharge transfer: Conduction (electrical)

Data Source

PatentUS20250008751A1Image pickup element, stacked image pickup element, and solid image pickup apparatus

Publication Date: 2025.01.02 SONY SEMICON SOLUTIONS CORP

AI summary

An image pickup element includes a photoelectric conversion section including a first electrode, a photoelectric conversion layer including an organic material, and a second electrode stacked on one another. Between the first electrode and the photoelectric conversion layer, an oxide semiconductor layer and an oxide film are formed from the first electrode side.