Pixelated Optoelectronic Stack Layout for Low-Crosstalk Pixels

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Solution Overview

Problem

Current methods for fabricating pixelated optoelectronic devices face issues such as crosstalk noise between pixels, surface defects, reduced reflectivity, and adhesion problems due to the etching process, especially when scaling down pixel size, and challenges in scaling up organic/inorganic film devices for CMOS fabrication.

Innovation Solution

A method involving forming an optoelectronic stack on a bottom electrode before pixelating both, using a patterned hard-mask to replicate the pixel pattern, and then applying an electrically insulating layer to isolate pixels, minimizing thermal treatment and ambient exposure to prevent degradation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If the bottom electrode is pixelated by selective etching before depositing the optoelectronic stack, then crosstalk noise between pixels is reduced, but surface defects are introduced and reflectivity is reduced

Engineering Contradiction:

Improvecrosstalk noiseVSAvoidsurface smoothness

Core Design Contradiction:

Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The optoelectronic stack is deposited on the continuous bottom electrode before pixelation occurs. This preliminary deposition ensures that the electrode surface remains smooth and defect-free during the stacking process, and pixelation is performed afterward when the stack provides protection and context for the etching process.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The conventional sequence is inverted: instead of pixelating the bottom electrode first and then depositing the stack, the method deposits the complete optoelectronic stack on the continuous electrode first, and only then performs pixelation through selective etching. This inversion resolves the contradiction by ensuring the electrode surface remains intact during stack formation.

Inventive Principle:

Principle #13The other way round (Inversion)

2Productivity

If pixel size is scaled down to increase pixel density, then device integration is improved, but crosstalk noise dramatically increases

Engineering Contradiction:

Improvepixel densityVSAvoidcrosstalk noise

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The optoelectronic stack is deposited before pixelation, creating a continuous protective layer over the entire electrode surface. When pixelation subsequently occurs through selective etching, this pre-formed stack structure helps contain and isolate charge carriers within future pixel boundaries, reducing crosstalk even as pixel dimensions shrink and spacing decreases.

Inventive Principle:

Principle #10Preliminary action

3Object-affected harmful factors

If the bottom electrode is etched before stack deposition, then pixel isolation is improved, but adhesion between stack and electrode deteriorates

Engineering Contradiction:

Improvecrosstalk noiseVSAvoidadhesion

Core Design Contradiction:

Object-affected harmful factorsVSStrength

Solution Approach 1:

The optoelectronic stack is deposited on the continuous, unetched bottom electrode surface before pixelation occurs. This ensures optimal adhesion between the stack and electrode, as the electrode surface remains clean and intact during deposition. Pixel isolation is subsequently achieved through selective etching of the already-adhered stack structure, preserving both adhesion strength and pixel isolation.

Inventive Principle:

Principle #10Preliminary action

4Stability of the object's composition

If thermal treatment time is increased during fabrication, then material crystallization is improved, but organic material degradation increases

Engineering Contradiction:

Improvematerial crystallizationVSAvoidmaterial degradation

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The optoelectronic stack is deposited before pixelation and subsequent thermal processing steps. This preliminary deposition allows the stack materials to be deposited in their optimal form, and subsequent thermal treatment during pixelation can be better controlled and localized, reducing overall thermal exposure time and preventing organic material degradation while still achieving necessary crystallization.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS11929385B2Method for forming a pixelated optoelectronic device on a substrate

Publication Date: 2024.03.12 INTERUNIVERSITAIR MICRO ELECTRONICS CENT (IMEC VZW)

AI summary

A method for forming a pixelated optoelectronic stack comprises forming a stacked layer structure that comprises a bottom electrode layer, an optoelectronic layer over the bottom electrode layer, and a patterned hard-mask comprising a pattern over the optoelectronic layer. The method comprises replicating the pattern into the optoelectronic layer and the bottom electrode layer, thereby forming a first intermediate pixelated stack comprising at least two islands of stack separated from one another by stack-free areas; providing an electrically insulating layer on the first intermediate pixelated stack; removing a top portion of the electrically insulating layer and removing any remaining hard-mask so that a top surface of the electrically insulating layer is coplanar with an exposed top surface of the first intermediate pixelated stack, yielding a second intermediate pixelated stack; and forming a top transparent electrode layer over the second intermediate pixelated stack.