OLED Thin-Film Encapsulation with Plasma SiN Barrier Stacks

Solution Overview

Problem

Conventional thin-film encapsulants for OLED devices are thick, reducing flexibility and durability due to their moisture and oxygen-blocking properties, leading to potential cracking under stress and limited OLED device lifespan.

Innovation Solution

A method involving the use of high-density plasma chemical vapor deposition to form thin-film encapsulants with reduced thickness, comprising multiple layers of silicon nitride barrier layers and buffer layers, which effectively block moisture and oxygen while maintaining flexibility and durability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the thin-film encapsulant thickness is increased to improve moisture and oxygen blocking properties, then the barrier performance is improved, but the flexibility and durability of the OLED device deteriorate due to cracking under stress

Engineering Contradiction:

Improvemoisture and oxygen blocking performanceVSAvoidflexibility and durability

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The encapsulant is divided into multiple thin alternating layers of first and second materials with different stress properties. This segmentation allows each layer to be thinner individually while collectively providing the required barrier performance, and the alternating stress characteristics prevent cracking under bending stress.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention uses a composite structure with alternating layers of different materials (first material and second material) that have different stress characteristics. This composite approach combines the moisture-blocking capability of thin layers with the flexibility and crack-resistance of materials having opposing stress properties, resolving the contradiction between barrier performance and mechanical durability.

Inventive Principle:

Principle #40Composite materials

2Strength

If the thin-film encapsulant thickness is reduced to improve flexibility and durability, then the flexibility and durability are improved, but the moisture and oxygen blocking performance deteriorates

Engineering Contradiction:

Improveflexibility and durabilityVSAvoidmoisture and oxygen blocking performance

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The encapsulant is divided into multiple thin alternating layers of first and second materials with different stress properties. This segmentation allows each layer to be thinner individually while collectively providing the required barrier performance, and the alternating stress characteristics prevent cracking under bending stress.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention uses a composite structure with alternating layers of different materials (first material and second material) that have different stress characteristics. This composite approach combines the moisture-blocking capability of thin layers with the flexibility and crack-resistance of materials having opposing stress properties, resolving the contradiction between barrier performance and mechanical durability.

Inventive Principle:

Principle #40Composite materials

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

The method achieves improved moisture and oxygen-blocking properties with reduced encapsulant thickness, enhancing the flexibility and durability of OLED devices and preventing cracking under stress, while maintaining effective barrier performance.

Implementation Method 1

depositing a first barrier layer comprising silicon and nitrogen over the OLED by generating a second plasma comprising silicon and nitrogen in the process chamber

Methodology Applied

Scientific EffectPlasma enhanced chemical vapor deposition: Plasma Enhanced Chemical Vapour Deposition

Implementation Method 2

generating a first plasma in a process chamber, the first plasma having an electron density of at least 10^11 cm^-3

Methodology Applied

Scientific EffectPlasma: Plasma

Data Source

PatentUS11770964B2Thin-film encapsulation

Publication Date: 2023.09.26 APPLIED MATERIALS INC

AI summary

A method of encapsulating an organic light emitting diode (OLED) is provided. The method includes generating a first plasma in a process chamber, the first plasma having an electron density of at least 1011 cm−3 when an OLED device is positioned within the process chamber. The OLED device includes a substrate and an OLED formed on the substrate. The method further includes pretreating one or more surfaces of the OLED and substrate with the first plasma; depositing a first barrier layer comprising silicon and nitrogen over the OLED by generating a second plasma comprising silicon and nitrogen in the process chamber, the second plasma having an electron density of at least 1011 cm−3, and depositing a buffer layer over the first barrier layer; and depositing a second barrier layer comprising silicon and nitrogen over the buffer layer by generating a third plasma comprising silicon and nitrogen in the process chamber.