Moth-Eye Image Sensor Structure for Low Reflection and Film Adhesion

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Solution Overview

Problem

Existing solid-state image pickup devices face issues with light reflection, leading to phenomena such as flare, ghost, and blooming, which can cause noise and deteriorate the device's sensitivity and yield due to the moth-eye structure's influence on insulation films and color filters.

Innovation Solution

The device incorporates a moth-eye section with recessed and projected portions on the semiconductor substrate, where the recessed portion has a curvature or polygonal shape, and a region with a different refractive index, to reduce light reflection and prevent uneven mold or peeling of the insulation film and color filter, enhancing adhesion and sensitivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a moth-eye structure is formed on the semiconductor substrate to reduce light reflection, then light reflection is reduced, but uneven mold or peeling occurs in the insulation film or color filter, causing noise and deteriorating sensitivity

Engineering Contradiction:

Improvelight reflectionVSAvoidadhesion of insulation film and color filter

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent applies curvature to the recessed portions of the moth-eye structure, transforming the sharp corners into rounded surfaces. This curvature prevents stress concentration and eliminates uneven mold or peeling in the insulation film and color filter, while maintaining the light reflection reduction effect of the moth-eye structure

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The patent modifies only the local geometry of the recessed portions (adding curvature) while keeping the overall moth-eye structure intact. This localized modification addresses the adhesion problem without compromising the global light reflection reduction function

Inventive Principle:

Principle #3Local quality

2Object-affected harmful factors

If a moth-eye structure is formed on the semiconductor substrate, then light reflection is reduced, but noise is caused on the interface between the insulation film or color filter and the semiconductor substrate

Engineering Contradiction:

Improvelight reflectionVSAvoidnoise on interface

Core Design Contradiction:

Object-affected harmful factorsVSLoss of information

Solution Approach 1:

By rounding the recessed portions of the moth-eye structure, the patent eliminates sharp corners that cause stress concentration and interface defects. This curvature modification prevents noise generation at the interface between the insulation film/color filter and semiconductor substrate

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Object-affected harmful factors

If a moth-eye structure is formed on the semiconductor substrate, then light reflection is reduced, but the yield of the solid-state image pickup device is lowered

Engineering Contradiction:

Improvelight reflectionVSAvoidyield

Core Design Contradiction:

Object-affected harmful factorsVSProductivity

Solution Approach 1:

The curvature modification of recessed portions prevents manufacturing defects such as uneven mold and peeling, thereby improving process yield without requiring additional manufacturing steps or complex processes

Inventive Principle:

Principle #14Spheroidality (Curvature)

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 effectively reduces light reflection, prevents noise, and improves the yield and sensitivity of the solid-state image pickup device by ensuring better adhesion between the semiconductor substrate and the insulation film or color filter, thereby enhancing the device's performance.

Implementation Method 1

A moth-eye section 125 that includes recesses and projections formed on a surface on a light incident side in the semiconductor substrate... providing a moth-eye structure allows the refractive index to slowly vary along the incident direction of light, thereby reducing the reflection of light

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 2

a photoelectric conversion section that is arranged on a semiconductor substrate and configured to photoelectrically convert an incident light

Methodology Applied

Scientific EffectPhotoelectric conversion: Photoelectric Effect

Data Source

PatentUS12015039B2Image pickup device and electronic apparatus

Publication Date: 2024.06.18 SONY GROUP CORP

AI summary

The present technology relates to an image pickup device and an electronic apparatus that are configured to enhance characteristics. A solid-state image pickup device includes a photoelectric conversion section that is arranged on a semiconductor substrate and configured to photoelectrically convert an incident light, a moth-eye section that includes recesses and projections formed on a surface on a light incident side in the semiconductor substrate and has, when a cross section approximately parallel to a direction toward the photoelectric conversion section from the light incident side is viewed, a recessed portion protruding toward the side of the photoelectric conversion section, the recessed portion having a curvature or a polygonal shape, and a region that is arranged adjacent to and opposite to the photoelectric conversion section of the moth-eye section and has a refractive index different from a refractive index of the semiconductor substrate.