Intermittent Sputtering for Display Electrode Defect Control
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Solution Overview
Problem
In the manufacturing of display devices with organic electroluminescent elements, foreign substances generated during the sputtering process can lead to defects in the sealing layer, causing moisture to enter and deteriorate the organic layer, which existing methods fail to effectively prevent due to limitations in film deposition techniques.
Innovation Solution
An intermittent film deposition method is employed, where film deposition by sputtering is alternated with vacuum evacuation to control the growth of particles, reducing the adhesion of foreign substances to the substrate, and a cleaning treatment is applied to manage the accumulated film thickness and remove deposits in the non-erosion region of the sputtering target.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If continuous sputtering deposition is used to form the second electrode, then the film thickness can be controlled, but foreign substances accumulate and adhere to the substrate causing sealing layer defects
Solution Approach 1:
The continuous sputtering deposition process is segmented into multiple intermittent deposition cycles. Each cycle consists of a deposition step followed by a vacuum evacuation step. This segmentation prevents foreign substance accumulation by removing particles from the vacuum chamber between deposition cycles, while still achieving the target film thickness through repeated thin layer deposition.
Solution Approach 2:
The sputtering deposition is performed periodically with alternating deposition steps and vacuum evacuation steps. This periodic action allows the system to deposit thin film layers while intermittently clearing accumulated foreign substances from the chamber, thereby maintaining film quality and preventing sealing layer defects over the course of forming the complete second electrode.
2Reliability
If sputtering is performed to deposit transparent conductive film, then the electrode can be formed with desired conductivity, but ions and high energy electrons damage the underlying organic layer
Solution Approach 1:
Instead of using high-power continuous sputtering that would damage the organic layer, the patent uses multiple low-power intermittent deposition steps. Each step deposits a thin layer with sufficient conductivity while the low power setting prevents excessive ion and electron bombardment that would damage the underlying organic layer. The cumulative effect achieves the desired electrode conductivity without harmful damage.
3Reliability
If the sealing layer is formed to protect the organic EL element, then moisture protection is improved, but defects from foreign substances cause moisture ingress
Solution Approach 1:
The patent performs preliminary vacuum evacuation steps between each sputtering deposition cycle to remove foreign substances before they can adhere to the substrate and create defects. By proactively clearing the vacuum chamber of particles during the electrode formation process, the subsequent sealing layer can be formed without underlying defects, ensuring intact moisture protection.
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 significantly reduces the number of large foreign substances adhering to the substrate, minimizing defects in the sealing layer and improving the reliability of the display device by preventing moisture ingress and organic layer deterioration.
Implementation Method 1
A transparent conductive film such as indium tin oxide is fabricated by a sputtering method.
Implementation Method 2
film deposition by sputtering is alternated with vacuum evacuation to control the growth of particles
Data Source
AI summary
A method for manufacturing a display device includes forming an insulating layer embedding a transistor arranged on a substrate, forming a first electrode electrically connected with the transistor above the insulating layer, forming a partition wall layer having an opening part covering a periphery edge part of the first electrode and exposing an inner side region of the first electrode, forming an organic layer including an organic electroluminescent material above the first electrode, forming a second electrode above the partition layer and the organic layer, and forming a sealing layer above the second electrode. Deposition of the second electrode includes a film deposition step of an electrode layer having a thinner film thickness than a target film thickness of the second electrode, and a waiting step after completion of the deposition step of the electrode layer.