Photodetector Condenser with Multi-Layer Inorganic Refractive Index Structure

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Solution Overview

Problem

Current photodetectors with avalanche photodiodes face challenges in achieving high light collection efficiency due to complex manufacturing processes and the need for advanced lithography techniques, making it difficult to miniaturize pixels while maintaining effective light collection.

Innovation Solution

A photodetector design featuring a semiconductor substrate with a photoelectric converter and a condenser that includes a first inorganic material layer with a higher refractive index overlapping the converter and a second layer with a lower refractive index covering it, improving light collection efficiency without requiring intricate manufacturing processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a single-layer condenser structure is used, then the manufacturing process is simple, but the light collection efficiency is insufficient

Engineering Contradiction:

Improvemanufacturing process simplicityVSAvoidlight collection efficiency

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The condenser is divided into multiple inorganic material layers with different refractive indices. This segmentation allows each layer to contribute differently to light collection, improving overall efficiency while maintaining a relatively simple manufacturing process using standard semiconductor fabrication techniques.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The condenser uses composite inorganic material layers with different refractive indices stacked together. This composite structure optimizes light collection by utilizing the optical properties of each material layer, achieving high light collection efficiency without requiring complex manufacturing processes.

Inventive Principle:

Principle #40Composite materials

2Manufacturing precision

If advanced lithography techniques are used to improve light collection efficiency, then the light collection efficiency increases, but the device complexity and manufacturing difficulty increase

Engineering Contradiction:

Improvelight collection efficiencyVSAvoidmanufacturing process complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

Instead of using advanced lithography to create complex single-layer patterns, the patent segments the condenser into multiple inorganic material layers. This approach achieves high light collection efficiency through material layering rather than complex lithographic patterning, reducing device complexity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the refractive index parameter by using different inorganic materials for each layer. This parameter change approach improves light collection efficiency through material selection rather than geometric complexity, avoiding the need for advanced lithography techniques.

Inventive Principle:

Principle #35Parameter changes

3Area of moving object

If pixel size is reduced for miniaturization, then the device integration increases, but the light collection efficiency decreases

Engineering Contradiction:

Improvepixel sizeVSAvoidlight collection efficiency

Core Design Contradiction:

Area of moving objectVSManufacturing precision

Solution Approach 1:

The multi-layer inorganic material condenser uses composite materials with different refractive indices to maximize light collection within the reduced pixel area. This composite structure allows efficient light collection even in miniaturized pixels where single-layer condensers would be insufficient.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

Each inorganic material layer is positioned and sized to optimize light collection locally within the pixel structure. This local optimization through stratified material placement ensures high light collection efficiency even when the overall pixel dimensions are reduced for miniaturization.

Inventive Principle:

Principle #3Local quality

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 design simplifies the manufacturing process and enhances light collection efficiency, allowing for more efficient detection of near-infrared light while maintaining excellent temperature characteristics, thus improving the reliability and performance of photodetectors.

Implementation Method 1

a condenser opposed to the photoelectric converter and including a first inorganic material layer and a second inorganic material layer with a refractive index lower than a refractive index of the first inorganic material layer

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentUS20230164462A1Photodetector, solid-state image sensor, and method of manufacturing photodetector

Publication Date: 2023.05.25 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

A photodetector includes a semiconductor substrate; a photoelectric converter in the semiconductor substrate; and a condenser light-transmissive and opposed to the photoelectric converter. The condenser includes: an inorganic material layer at least partially overlapping the photoelectric converter in a plan view; and an inorganic material layer covering the inorganic material layer and having a refractive index lower than a refractive index of the inorganic material layer.