Light-Emitting Device Substrate Segmentation for Defect Reduction
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Solution Overview
Problem
Conventional light-emitting device manufacturing processes result in irregularities and defects such as point and line defects due to steps formed in the layer below the light-emitting elements, limiting the area for forming these elements and reducing yield.
Innovation Solution
The light-emitting device is manufactured by forming the light-emitting element and driver circuit on different substrates and electrically connecting them, allowing for separate processing steps and reduced surface irregularities, thereby minimizing defects and improving yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If light-emitting elements and driver circuits are formed on the same substrate in stacked layers, then integration is achieved, but surface irregularities and steps occur that limit the area for forming light-emitting elements and cause coverage defects
Solution Approach 1:
The device is divided into two separate substrates: a first substrate for forming light-emitting elements and a second substrate for forming driver circuits. This segmentation eliminates the surface irregularities caused by stacking multiple functional layers on a single substrate, while still achieving integration through electrical connection between the substrates.
Solution Approach 2:
Instead of integrating functions vertically within the same plane (2D integration leading to stacked layers), the invention transitions to 3D integration by using separate substrates that can be electrically connected through conductive structures extending between substrates. This dimensional change allows both functions to coexist without surface interference.
2Reliability
If driver circuits are formed in the layer below light-emitting elements, then electrical connection is achieved, but steps and irregularities cause coverage defects and reduce yield
Solution Approach 1:
By separating driver circuits and light-emitting elements onto different substrates, the invention eliminates coverage defects caused by surface steps, thereby improving manufacturing yield while maintaining electrical connection reliability through dedicated conductive pathways between substrates.
3Reliability
If insulating films are added to separate driver circuits from light-emitting elements, then electrical isolation is achieved, but the area for forming light-emitting elements is limited due to steps from lower layers
Solution Approach 1:
Placing driver circuits and light-emitting elements on separate substrates eliminates the need for thick insulating films to cover steps from lower layers. This segmentation maximizes the usable area on each substrate while maintaining proper electrical isolation between the two functional components.
Data Source
AI summary
To prevent a point defect and a line defect in forming a light-emitting device, thereby improving the yield. A light-emitting element and a driver circuit of the light-emitting element, which are provided over different substrates, are electrically connected. That is, a light-emitting element and a driver circuit of the light-emitting element are formed over different substrates first, and then electrically connected. By providing a light-emitting element and a driver circuit of the light-emitting element over different substrates, the step of forming the light-emitting element and the step of forming the driver circuit of the light-emitting element can be performed separately. Therefore, degrees of freedom of each step can be increased, and the process can be flexibly changed. Further, steps (irregularities) on the surface for forming the light-emitting element can be reduced than in the conventional technique.