Micro LED Display Coplanar Bonding via Semiconductor Heightening
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Solution Overview
Problem
In micro light-emitting diode displays, the process of fabricating a metal heightening layer increases time and costs, and the film thickness accuracy of this layer can lead to poor bonding yields due to the need for additional processing steps.
Innovation Solution
The use of a semiconductor heightening portion or insulating heightening portion, which is fabricated during the process of creating semiconductor light-emitting mesas, eliminates the need for a separate metal heightening layer, ensuring that the bonding regions for both types of semiconductors are coplanar, thereby reducing process time and costs and improving bonding yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a metal heightening layer is disposed to make bonding regions coplanar, then bonding alignment is improved, but process time and costs increase due to additional fabrication steps
Solution Approach 1:
The patent merges the heightening function with the semiconductor light-emitting mesas themselves by forming them to protrude from the substrate. This combines the light-emitting function and the heightening function into a single structure, eliminating the need for a separate metal heightening layer and its associated fabrication steps.
Solution Approach 2:
The patent extracts the heightening function from the metal layer and transfers it to the semiconductor mesas. By removing the metal heightening layer requirement, the process complexity is reduced while maintaining the coplanar bonding surface capability.
2Manufacturing precision
If a metal heightening layer is disposed to make bonding regions coplanar, then bonding alignment is improved, but manufacturing costs increase due to additional processes
Solution Approach 1:
The patent merges the heightening function with the semiconductor light-emitting mesas themselves by forming them to protrude from the substrate. This combines the light-emitting function and the heightening function into a single structure, eliminating the need for a separate metal heightening layer and its associated fabrication steps.
Solution Approach 2:
The patent uses the semiconductor mesas, which are already being fabricated for light emission, to serve the dual purpose of light emission and heightening. This avoids the need for expensive additional metal layer deposition processes.
3Reliability
If film thickness accuracy of metal heightening layer is increased to ensure coplanar bonding, then bonding yield is improved, but process complexity and costs increase
Solution Approach 1:
The patent merges the heightening function with the semiconductor light-emitting mesas themselves by forming them to protrude from the substrate. This combines the light-emitting function and the heightening function into a single structure, eliminating the need for a separate metal heightening layer and its associated fabrication steps.
Solution Approach 2:
The patent changes the approach from controlling metal layer thickness parameters to controlling semiconductor mesa height parameters. The mesas are formed to a specific height that naturally provides the required coplanar bonding surface, eliminating the need for precise metal film thickness control.
Data Source
AI summary
A micro light-emitting diode display includes a first-type semiconductor base layer, a plurality of semiconductor light-emitting mesas dispersedly disposed on the first-type semiconductor base layer, a semiconductor heightening portion disposed on the first-type semiconductor base layer, a first bonding metal layer disposed on the semiconductor heightening portion, and a plurality of second bonding metal layers respectively disposed on the semiconductor light-emitting mesas. A top surface of the semiconductor heightening portion and a plurality of top surfaces of the semiconductor light-emitting mesas facing away from the first-type semiconductor base layer are coplanar. The top surface of the semiconductor heightening portion forms a first bonding surface adjacent to the first bonding metal layer. The top surfaces of the semiconductor light-emitting mesas respectively form a plurality of second bonding surfaces adjacent to the second bonding metal layers, and the first bonding surface and the second bonding surfaces are coplanar.