Heterojunction Image Sensor for Selective Infrared Charge Transfer

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Solution Overview

Problem

Existing solid-state imaging devices face challenges in efficiently using near-infrared or short-wave infrared light and achieving appropriate selective carrier transfer due to interference from diffusion layers between photodiodes and gates, as described in PTL 1.

Innovation Solution

A solid-state image sensor with a first semiconductor composed of Ge or Ge compounds and a second semiconductor of silicon, featuring a heterojunction configuration with transfer controllers and carrier storages, allowing selective transfer of charge carriers without large-capacitance capacitors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a cooling structure is added to reduce heat accumulation in high-aperture lenses, then heat dissipation is improved, but device complexity and manufacturing difficulty increase

Engineering Contradiction:
Improveheat accumulationVSAvoidstructure complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The patent combines the lens holder and cooling structure into a single integrated component. The lens holder serves dual functions: supporting the lens and dissipating heat through built-in heat dissipation fins, eliminating the need for separate cooling structures and reducing overall device complexity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The lens holder is designed with multi-functionality, simultaneously performing mechanical support for the lens and thermal management through integrated heat dissipation fins. This universal design reduces the number of components while effectively addressing both structural and thermal requirements.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If the number of lenses is increased to expand the imaging range, then adaptability is improved, but manufacturing precision and assembly difficulty worsen

Engineering Contradiction:
Improveimaging rangeVSAvoidassembly precision
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent divides the imaging system into multiple independent lens units, each capable of capturing a specific field of view. These segmented lens units can be independently manufactured and calibrated, then assembled together to achieve a comprehensive wide-angle imaging capability, reducing the precision requirements for each individual component.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transitions from a single-lens design to a multi-lens array configuration, adding spatial dimensionality to the imaging system. This dimensional change allows the system to capture a broader field of view by combining multiple narrow-field lenses, making the imaging range expansion more manageable through modular assembly.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Illumination intensity

If lens aperture is increased to improve light intake, then illumination intensity is improved, but heat accumulation worsens

Engineering Contradiction:
Improvelight intakeVSAvoidheat accumulation
Core Design Contradiction:
Illumination intensityVSTemperature

Solution Approach 1:

The patent converts the harmful heat generated by high-aperture lenses into a manageable thermal management challenge by integrating heat dissipation fins directly into the lens holder. The same structure that supports the high-aperture lens also actively dissipates the heat it generates, turning a potential failure mode into a controlled thermal management solution.

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

Enables efficient use of near-infrared or short-wave infrared light and achieves appropriate selective carrier transfer, improving the imaging device's performance and reducing noise from external light.

Implementation Method 1

a plurality of infrared detectors arranged in an array fashion are respectively coupled to the plurality of microlenses

Methodology Applied
Scientific EffectPhotoelectric Effect: Photoelectric Effect

Data Source

PatentEP4131940B1Solid-state image sensor and imaging system
Publication Date: 2026.05.06 TOPPAN INC
  • EP4131940B1 patent drawingFigure 1
  • EP4131940B1 patent drawingFigure 2
  • EP4131940B1 patent drawingFigure 3~4

AI summary

A solid-state image sensor includes a first semiconductor, and a second semiconductor having a composition different from that of the first composition and electrically connected to the first semiconductor. The first semiconductor includes a photodiode configured to convert light incident on the photodiode into charge carriers; a plurality of first carrier storages for storing the charge carriers; and a transfer gate configured to transfer the charge carriers to a selected one of the first carrier storages. The second semiconductor includes a plurality of second carrier storages and a potential detection node. The second carrier storages are each configured to store charge carriers based on the charge carriers stored in a corresponding one of the first carrier storages. The potential detection node is configured to detect the electric potential of each of the second carrier storages. The solid-state image sensor further includes a reset transistor configured to reset the electric potential of each of the first carrier storages to a predetermined electric potential.