Electroluminescent Pixel Etching for Thick Dielectric Layers

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Solution Overview

Problem

Existing methods for manufacturing electroluminescent devices, particularly those using gallium nitride nanowires, face issues such as pixel degradation due to ionized gas bombardment and etching depth variability, especially when the dielectric layer is thick, leading to unwanted beveling and etch stop phenomena.

Innovation Solution

A method involving directional etching of the dielectric layer between pixel matrices, followed by selective chemical etching using hydrofluoric acid, which protects the upper pixel parts and allows precise control over the etching process, reducing degradation and etching stopping problems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If plasma etching is used to etch the dielectric layer, then etching efficiency is improved, but pixel degradation occurs due to intense ionized gas bombardment

Engineering Contradiction:

Improveetching efficiencyVSAvoidpixel degradation

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The etching process is divided into two distinct stages: a first plasma etching step that etches through the carbon mask and removes the upper portion of the dielectric layer, and a second plasma etching step that completes the etching after the mask is removed. This segmentation allows the carbon mask to protect pixels during the first stage while enabling complete dielectric layer removal in the second stage.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A carbon-based mask is deposited on the dielectric layer before the first plasma etching step. This preliminary action provides protective coverage for the pixel structures during the initial etching process, preventing ionized gas bombardment damage while allowing controlled etching of the dielectric layer.

Inventive Principle:

Principle #10Preliminary action

2Length of stationary object

If the thickness of the dielectric layer is increased to improve device performance, then device performance is improved, but etching stoppage occurs during plasma etching

Engineering Contradiction:

Improvedielectric layer thicknessVSAvoidetching consistency

Core Design Contradiction:

Length of stationary objectVSReliability

Solution Approach 1:

The etching of thick dielectric layers is divided into multiple plasma etching steps with intermediate mask removal and recarbonization. This segmentation prevents etching stoppage by refreshing the carbon mask coverage during the process, maintaining consistent etching rates throughout the entire thickness of the dielectric layer.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The carbon mask is continuously maintained and refreshed throughout the etching process. After the first etching step, the mask is removed, pixels are recarbonized, and the mask is redeposited before the second etching step. This continuous maintenance of the protective carbon layer ensures consistent etching action throughout the entire process.

Inventive Principle:

Principle #20Continuity of useful action

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 effectively protects the columnar pixels from degradation and ensures consistent etching without affecting the upper parts, overcoming the limitations of traditional plasma etching, especially for thick dielectric layers, thereby enhancing the manufacturing process for electroluminescent devices.

Implementation Method 1

perform a directional etch, along the normal to the surface of the substrate, of a portion of the dielectric layer extending between the pixels of the pixel arrays

Methodology Applied

Scientific EffectDirectional etching:

Implementation Method 2

perform a selective chemical etch of the remaining portion of the dielectric layer; step c) being carried out with a chemical etching agent allowing selective etching of the remaining portion of the dielectric layer with respect to the encapsulation layer

Methodology Applied

Scientific EffectSelective chemical etching:

Implementation Method 3

selective chemical etching with hydrofluoric acid vapor phase

Methodology Applied

Scientific EffectHydrofluoric acid vapor phase etching:

Implementation Method 4

step b) is executed with a photolithography mask having patterns arranged to face the pixels of the pixel matrices

Methodology Applied

Scientific EffectPhotolithography masking:

Data Source

PatentEP4492469A1Method for manufacturing a light emitting device

Publication Date: 2025.01.15 COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES

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AI summary

A method for manufacturing an electroluminescent device, comprising the steps: a) using a stack comprising successively: - a substrate (1), having a surface (10); - columnar pixel arrays (2), formed on the surface (10) of the substrate (1); - an encapsulation layer (3), arranged to cover the pixel arrays (2); - a dielectric layer (4), formed on the encapsulation layer (3); b) performing a directional etching, along the normal to the surface (10) of the substrate (1), of a portion of the dielectric layer (4) extending between the pixels (2) of the pixel arrays (2); the dielectric layer (4) having a remaining portion (40) after step b); c) perform a selective chemical etching of the remaining part (40) of the dielectric layer (4), with a chemical etching agent allowing a selective etching of the remaining part (40) of the dielectric layer (4) with respect to the encapsulation layer (3).