Multilayer Barrier Stack Plasma Damage Mitigation
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Solution Overview
Problem
Devices encapsulated with multilayer barrier stacks often suffer from plasma damage during the deposition of barrier and decoupling layers, leading to adverse effects on their electrical and luminescent characteristics, particularly in plasma-sensitive devices like OLEDs, due to interactions with ions, electrons, neutral species, and UV radiation.
Innovation Solution
The method involves depositing a polymeric decoupling layer followed by a first inorganic non-barrier layer under low ion and neutral energy conditions (less than 20 eV) and a second inorganic barrier layer under higher energy conditions (greater than 50 eV), with the option of using a screen to limit neutral flux and applying a protective layer like LiF to mitigate damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If plasma-based deposition processes are used to deposit barrier layers, then barrier properties are improved, but plasma damage to the polymeric decoupling layer occurs
Solution Approach 1:
The inorganic barrier layer is divided into two distinct layers: a first inorganic non-barrier layer deposited under low-energy conditions to protect the polymer, and a second inorganic barrier layer deposited under high-energy conditions to provide barrier properties. This segmentation allows each layer to serve its specific function without compromising the other.
Solution Approach 2:
The first inorganic non-barrier layer is deposited beforehand to create a protective interface between the polymeric decoupling layer and the subsequent high-energy plasma process. This preliminary layer prevents direct plasma damage to the polymer while still allowing the second barrier layer to be effectively deposited.
2Manufacturing precision
If high ion and neutral energy is used during deposition, then barrier layer quality is improved, but damage to the polymeric decoupling layer increases
Solution Approach 1:
Different regions of the inorganic barrier structure have different qualities: the first layer has low-density, non-barrier properties optimized for polymer protection, while the second layer has high-density, barrier properties optimized for gas/vapor blocking. Each layer's quality is tailored to its specific location and function.
Solution Approach 2:
The deposition parameters (ion and neutral energy) are changed between depositing the two layers. The first layer is deposited at low energy (<20 eV) to protect the polymer, while the second layer is deposited at high energy (>50 eV) to achieve barrier properties, demonstrating dynamic parameter adjustment.
3Reliability
If a protective layer is added to prevent plasma damage, then polymer integrity is improved, but device complexity increases
Solution Approach 1:
The first inorganic layer serves multiple functions: it acts as a protective buffer against plasma damage, provides a nucleation substrate for the second barrier layer, and maintains structural integrity. This multi-functionality reduces the need for additional separate protective layers.
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 reduces polymer plasma damage, maintaining the integrity and performance of the encapsulated devices by minimizing the impact of high-energy processes on the polymeric decoupling layers, thereby enhancing the barrier properties without compromising the device's functionality.
Implementation Method 1
depositing a first inorganic layer on the decoupling layer under a first set of conditions wherein an ion and neutral energy arriving at the substrate is less than about 20 eV so that the first inorganic layer is not a barrier layer
Implementation Method 2
depositing a second inorganic layer on the first inorganic layer under a second set of conditions wherein an ion and neutral energy arriving at the substrate is greater than about 50 eV so that the second inorganic layer is a barrier layer
Implementation Method 3
with the option of using a screen to limit neutral flux and applying a protective layer like LiF to mitigate damage
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
An improved barrier stack. The barrier stack (315) is made by the process of depositing the polymeric.decoupling layer (320) on a substrate (305); depositing a first inorganic layer (330) on the decoupling layer under a first set of conditions wherein an ion and neutral energy arriving at the substrate is less than about 20 eV so that the first inorganic layer is not a barrier layer, wherein a temperature of the substrate is less than about 150 -C; and depositing a second inorganic layer (335) on the first inorganic layer under a second set of conditions wherein an ion and neutral energy arriving at the substrate is greater than about 50 eV so that the second inorganic layer is a barrier layer. Methods of reducing damage to a polymeric layer in a barrier stack are also described.