Solid-State Image Device Contact Activation via Laser Annealing

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Solution Overview

Problem

In solid-state imaging devices, the miniaturization of pixels leads to decreased sensitivity due to reduced photon incidence, and the stacking of photoelectric conversion layers results in issues like false color and junction leakage, particularly when using ion implantation for activation, which causes impurity diffusion and dark current problems.

Innovation Solution

A solid-state imaging device with an organic photoelectric conversion layer and a contact portion formed by self-alignment using a laser annealing process, where a reflecting film on the insulating layer directs laser light to selectively melt and activate the contact portion, preventing impurity diffusion and reducing junction leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If ion implantation with high concentration is used to form the contact portion, then activation is achieved, but impurities diffuse laterally causing junction leakage and dark current

Engineering Contradiction:

Improvecontact portion activationVSAvoidimpurity lateral diffusion

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent employs laser annealing to melt and rapidly solidify the contact portion region, achieving impurity activation through phase transition. This method concentrates the activation effect precisely where needed without causing lateral diffusion, resolving the contradiction between achieving activation and preventing impurity spread.

Inventive Principle:

Principle #36Phase transitions

Solution Approach 2:

The patent replaces the conventional thermal diffusion process with laser-induced phase transition. Instead of using thermal energy that causes lateral diffusion, the patent uses focused laser energy to melt and rapidly solidify the contact portion, achieving activation without the harmful lateral diffusion effect.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If pixel size is decreased for miniaturization, then device integration is improved, but sensitivity deteriorates due to reduced photon incidence

Engineering Contradiction:

Improvepixel integration densityVSAvoidphotoelectric conversion sensitivity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent transitions from planar photoelectric conversion to three-dimensional stacked photoelectric conversion layers. By stacking multiple photoelectric conversion layers vertically, the patent maintains high sensitivity despite pixel miniaturization, as each layer captures photons at different depths, effectively utilizing the vertical dimension to compensate for reduced horizontal area.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Adaptability or versatility

If multiple photoelectric conversion layers are stacked vertically, then color detection capability is improved, but junction leakage and dark current occur at contact portions

Engineering Contradiction:

Improvecolor detection capabilityVSAvoidjunction leakage and dark current

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The patent uses laser annealing-induced phase transition to form highly activated contact portions with precise spatial control. This method eliminates impurity diffusion that causes junction leakage and dark current, while maintaining the vertical stacking structure necessary for multi-color detection capability.

Inventive Principle:

Principle #36Phase transitions

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 approach enhances the reliability and image quality by preventing impurity diffusion and dark current issues, maintaining sensitivity while supporting pixel miniaturization.

Implementation Method 1

activation is carried out by laser annealing

Methodology Applied

Scientific EffectLaser annealing: Laser

Implementation Method 2

melt laser annealing may be used for melting silicon

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 3

a reflecting film reflecting laser light is formed on an insulating layer

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 4

an organic photoelectric conversion part including the organic photoelectric conversion layer is formed above the silicon substrate

Methodology Applied

Scientific EffectPhotoelectric conversion: Photoelectric Effect

Data Source

PatentUS10833128B2Reducing junction leakage and occurrence of dark current at a contact portion of a solid-state image device

Publication Date: 2020.11.10 SONY GROUP CORP

AI summary

There is provided a solid-state imaging device including a semiconductor base element, an organic photoelectric conversion layer formed above the semiconductor base element, a contact hole formed in an insulating layer on the semiconductor base element, a conductive layer formed in the contact hole and electrically connecting a photoelectric conversion part which includes the organic photoelectric conversion layer with the semiconductor base element, and a contact portion which is formed by self-alignment with the conductive layer in the contact hole in the semiconductor base element, and connected to the conductive layer.