Light Detector Pixel Isolation for Crosstalk Suppression

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Solution Overview

Problem

Current light detectors face challenges in increasing sensitivity while minimizing crosstalk noise, particularly as the thickness of the semiconductor region increases, leading to enhanced detection of long-wavelength light but with increased crosstalk noise and manufacturing complexities.

Innovation Solution

The light detector design incorporates a structure body with a first insulating portion, a second insulating portion, and a metal-including portion, where the thickness of the first insulating portion is greater than the second insulating portion, and the metal-including portion is positioned above the first insulating portion, effectively suppressing secondary photon penetration and crosstalk noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the thickness of the semiconductor region is increased to enhance sensitivity and detect long-wavelength light, then the sensitivity is improved, but the crosstalk noise increases

Engineering Contradiction:
ImprovesensitivityVSAvoidcrosstalk noise
Core Design Contradiction:
Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The patent divides the light detector into multiple independent pixel regions separated by structure bodies. Each pixel region is isolated by insulating portions and metal-including portions that prevent secondary photons generated in one pixel from affecting adjacent pixels, thereby suppressing crosstalk noise while maintaining the benefit of increased semiconductor thickness for sensitivity

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces structure bodies comprising insulating portions and metal-including portions as intermediary elements between adjacent pixel regions. These structure bodies act as barriers that absorb or reflect secondary photons, preventing them from penetrating into neighboring pixels and causing crosstalk, while allowing the semiconductor region thickness to be increased for improved sensitivity

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If the thickness of the semiconductor region is increased to improve light detection capability, then the detection performance is enhanced, but the manufacturing complexity increases

Engineering Contradiction:
Improvelight detection capabilityVSAvoidmanufacturing complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the detector into modular pixel regions with standardized structure bodies between them. This segmentation allows for systematic manufacturing where the same structure body design can be replicated across the device, making the increased thickness manageable through modular fabrication processes rather than requiring entirely new manufacturing approaches

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies different properties to different regions: the semiconductor region has increased thickness for light detection, while the structure bodies provide localized isolation functions. This local differentiation allows the thick semiconductor region to be manufactured using established processes, with the structure bodies added as specialized components to address crosstalk without complicating the overall manufacturing

Inventive Principle:
Principle #3Local quality

3Measurement precision

If the thickness of the semiconductor region is increased to detect long-wavelength light, then the long-wavelength detection is improved, but the crosstalk noise between adjacent pixels increases

Engineering Contradiction:
Improvelong-wavelength light detectionVSAvoidcrosstalk noise
Core Design Contradiction:
Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The patent introduces structure bodies comprising insulating portions and metal-including portions as intermediary elements between adjacent pixel regions. These structure bodies act as barriers that absorb or reflect secondary photons, preventing them from penetrating into neighboring pixels and causing crosstalk, while allowing the semiconductor region thickness to be increased for improved sensitivity

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent extracts harmful secondary photons from the system by using metal-including portions within the structure bodies to absorb or reflect them. This removal of harmful photons prevents them from causing crosstalk in adjacent pixels, allowing the semiconductor thickness to be increased for long-wavelength detection without the penalty of increased noise

Inventive Principle:
Principle #2Taking out (Extraction)

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 enhances the sensitivity of the light detector while maintaining low crosstalk noise, allowing for deeper semiconductor regions and improved light detection without the manufacturing difficulties associated with increased thickness.

Implementation Method 1

a first insulating portion, a metal-including portion, and a second insulating portion. The metal-including portion is provided above the first insulating portion

Methodology Applied
Scientific EffectElectrical insulation: Dielectric

Implementation Method 2

the metal-including portion is positioned above the first insulating portion, effectively suppressing secondary photon penetration and crosstalk noise

Methodology Applied
Scientific EffectPhoton reflection and absorption: Reflection

Implementation Method 3

A light detector detects light incident on a semiconductor region

Methodology Applied
Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentEP3886171A1Light detector, light detection system, lidar device, and vehicle
Publication Date: 2021.09.29 KK TOSHIBA
  • EP3886171A1 patent drawingFigure 1
  • EP3886171A1 patent drawingFigure 2
  • EP3886171A1 patent drawingFigure 3

AI summary

According to one embodiment, a light detector (100) includes an element (10), and a structure body (20). The element (10) includes a first semiconductor region (1), a second semiconductor region (2), and a third semiconductor region (3). The second semiconductor region (2) is provided on the first semiconductor region (1). The third semiconductor region (3) is provided on the second semiconductor region (2). The structure body (20) is provided around the element (10) in a first plane perpendicular to a first direction. The structure body (20) includes first and second insulating portions (21, 22) and a metal-including portion (25). The metal-including portion (25) is provided above the first insulating portion (21). A position in the first direction of at least a portion of the metal-including portion (25) is same as a position in the first direction of the third semiconductor region (3). The second insulating portion (22) is positioned between the metal-including portion (25) and the element (10) in the first plane. A thickness of the first insulating portion (21) is greater than a thickness of the second insulating portion (22) in the first plane.