Same-Surface Electrode Bonding for Micro-LED Contrast
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Solution Overview
Problem
The production of micro-LED chips faces challenges in connecting N-type and P-type electrodes to a drive circuit board without additional steps, leading to reduced contrast and external quantum efficiency due to light leakage and color mixing, and the existing methods do not achieve high yield or efficient light emission.
Innovation Solution
The LED unit features a nitride semiconductor with an N-type layer, light emitting layer, and P-type layer laminated in order, with a first wiring penetrating between the N-type and P-type layers and a second wiring connecting the P and N electrodes on the same surface, allowing simultaneous bonding of both electrodes to the drive circuit board.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If micro-LED chips are arranged in a two-dimensional array form, then light emission efficiency and long-term reliability are improved, but device complexity increases due to the need for separate connection of N-type and P-type electrodes to the drive circuit board
Solution Approach 1:
The patent merges the N electrode and P electrode onto the same surface of the micro-LED chip. The N electrode is formed on the same surface as the P electrode through a wiring structure that routes the N-type layer connection to the front surface, enabling both electrodes to be connected to the drive circuit board simultaneously in a single bonding process, thus reducing device complexity while maintaining high light emission efficiency
2Manufacturing precision
If additional connection steps are used to connect N-type and P-type electrodes separately, then manufacturing precision can be maintained, but productivity decreases due to multiple additional steps
Solution Approach 1:
The patent combines multiple electrode connection operations into a single bonding step by forming both N and P electrodes on the same surface. This merging of operations maintains manufacturing precision through consistent bonding conditions while significantly improving productivity by eliminating multiple separate connection steps and reducing the risk of defects from repeated handling
3Device complexity
If N-type GaN layer is not separated for each pixel, then device complexity is reduced, but contrast deteriorates due to light leakage to adjacent pixels
Solution Approach 1:
The patent applies segmentation by forming pixel separation grooves that divide the N-type GaN layer into isolated regions corresponding to individual pixels. This segmentation prevents light leakage from one pixel to adjacent pixels through the N-type layer, improving contrast while maintaining a relatively simple overall structure by using groove-based isolation rather than complete layer separation
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 configuration enables efficient connection of N and P electrodes to the drive circuit board in a single step, improving contrast, reducing light leakage, and enhancing external quantum efficiency, thereby addressing the issues of light emission and color rendering.
Implementation Method 1
a nitride semiconductor in which an N-type layer, a light emitting layer, and a P-type layer are laminated in this order
Data Source
AI summary
An N electrode and a P electrode formed on the same surface are respectively bonded to a cathode electrode and an anode electrode of a drive circuit board through a connection step performed once. An LED unit includes a first wiring (21) that is disposed inside a groove formed in a nitride semiconductor (13) to penetrate between an N-type layer (10) and a P-type layer (12) and is electrically connected to the N-type layer (10), and a second wiring that includes a P electrode (30) connected to the P-type layer (12) and an N electrode (31) connected to the first wiring (21), in which the N electrode (31) and the P electrode (30) are formed on the same surface.