LED Chip Bonding to Permanent Substrate via Eutectic Layer
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Solution Overview
Problem
Conventional LED manufacturing methods using wafer-bonding techniques face issues such as light absorption by the substrate, mechanical weakness, and efficiency reduction due to high temperatures and alloy procedures, as well as challenges in handling the light-emitting region after substrate removal.
Innovation Solution
The chip-bonding method involves forming ohmic contact dots, a reflecting layer, a barrier layer, and a eutectic layer on the light-emitting region, cutting the structure into chips, and bonding these chips to a permanent substrate using a chip-bonding technique, which allows for improved mechanical strength and reduced temperature processing, enhancing LED efficiency and yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If wafer-bonding technique is used to bond the light-emitting region to the permanent substrate, then the mechanical strength is improved, but the light-emitting region may be degraded due to high temperature processing
Solution Approach 1:
The bonding process is segmented into two stages: first bonding the light-emitting region to a temporary substrate at low temperature, then bonding the temporary substrate assembly to the permanent substrate. This segmentation allows the light-emitting region to avoid high temperature exposure while still achieving strong mechanical bonding to the permanent substrate.
Solution Approach 2:
A temporary substrate is introduced as an intermediary between the light-emitting region and the permanent substrate. The temporary substrate serves as a protective carrier during low-temperature bonding, shielding the light-emitting region from high temperature damage while enabling subsequent bonding to the permanent substrate.
2Loss of energy
If the temporary substrate is removed after light-emitting region formation, then the light absorption problem is solved, but the light-emitting region becomes difficult to handle and may break
Solution Approach 1:
The temporary substrate is removed only after the light-emitting region has been completely formed and bonded to the permanent substrate. This preliminary completion of all formation steps before substrate removal ensures the light-emitting region is stable and supported, eliminating handling difficulties and breakage risks.
3Loss of energy
If wafer-bonding is performed after temporary substrate removal, then the light absorption is reduced, but the light-emitting region is difficult to handle without breaking
Solution Approach 1:
The conventional sequence is inverted: instead of removing the temporary substrate first and then bonding, the light-emitting region is bonded to the permanent substrate while still supported by the temporary substrate. This inversion maintains structural integrity during bonding while still achieving the light transmission benefits.
4Strength
If high temperature wafer-bonding is used, then the bonding strength is improved, but the light-emitting region may be degraded
Solution Approach 1:
The bonding process is segmented into two separate bonding operations: first bonding the light-emitting region to the temporary substrate at low temperature to preserve quality, then bonding the assembly to the permanent substrate at high temperature to achieve strong bonding without degrading the light-emitting region.
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 results in improved LED efficiency by minimizing light absorption, maintaining mechanical strength, and reducing the risk of chip breakage, with the ability to process at lower temperatures, thereby enhancing the overall performance and cost-effectiveness of the LED manufacturing process.
Implementation Method 1
bonding the eutectic layer of the chip to the metal layer utilizing a chip-bonding technique
Implementation Method 2
a reflecting layer, a barrier layer, and a eutectic layer on a first surface of the light-emitting region
Data Source
AI summary
A light emitting diode comprises a permanent substrate having a chip holding space formed on a first surface of the permanent substrate; an insulating layer and a metal layer sequentially formed on the first surface of the permanent substrate and the chip holding space, wherein the metal layer comprises a first area and a second area not being contacted to each other; a chip having a first surface attached on a bottom of the chip holding space, contacted to the first area of the metal layer; a filler structure filled between the chip holding space and the chip; and a first electrode formed on a second surface of the chip. The chip comprises a light-emitting region and an electrical connection between the first area of the metal layer and the light emitting region is realized by using a chip-bonding technology.