High-Power LED Arrays via Segmented Mesa Fabrication

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The yield rate of high-power light-emitting diode (LED) arrays fabricated using wafer bonding methods drops significantly when the size exceeds 1×1 mm2, limiting the production of high-power LEDs with larger light-emitting areas.

Innovation Solution

A method involving etching grooves on a growth substrate to form mesas, fabricating indium gallium aluminum nitride (InGaAlN) multilayer structures, bonding these structures to a conductive substrate, removing the growth substrate, and creating conductive paths to couple adjacent LEDs for a shared power supply, forming high-power LED arrays without reducing yield rates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If wafer bonding is used to manufacture high-power LEDs with size greater than 1×1 mm2, then the light-emitting area and power increase, but the yield rate drops down to 80%

Engineering Contradiction:

ImproveLED powerVSAvoidyield rate

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The invention divides a large-area LED into multiple smaller LED units (e.g., 300×300 μm2) that are fabricated separately on the same wafer using wafer bonding. These small LEDs are then electrically connected in parallel to function as a single high-power LED array. This segmentation allows each small LED to maintain the high yield rate characteristic of wafer bonding while the collective array achieves the high power output of large LEDs.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention combines multiple small LED structures into a unified high-power LED array through electrical interconnection. The individual LEDs are bonded to a common substrate and their electrical contacts are connected in parallel, merging their light output and electrical function to achieve high power while preserving the manufacturing advantages of small-device fabrication.

Inventive Principle:

Principle #5Merging (Combining)

2Area of moving object

If the size of a single LED is increased to greater than 1×1 mm2 to generate high power, then the power output increases, but the fabrication yield rate decreases

Engineering Contradiction:

Improvelight-emitting areaVSAvoidyield rate

Core Design Contradiction:

Area of moving objectVSManufacturing precision

Solution Approach 1:

Instead of fabricating one large LED, the invention segments the light-emitting area into multiple small LED units (e.g., nine 300×300 μm2 LEDs arranged in a 3×3 pattern). Each small LED is fabricated with high precision using standard wafer bonding processes, ensuring high yield rates. The segmented units are then integrated into a functional array that provides the equivalent light output of a single large LED.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention transitions from a single large-area device in two dimensions to a multi-unit array that exploits the third dimension (vertical stacking and lateral arrangement on substrate). By arranging multiple small LEDs in a spatial array configuration, the invention achieves large effective light-emitting area without requiring any single device to be large, thereby maintaining manufacturing precision.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 allows for the fabrication of high-power LED arrays with improved yield rates similar to regular-sized LEDs, enabling increased luminance power without the yield rate decline associated with larger single LED fabrication.

Implementation Method 1

depositing a passivation layer and an electrode layer above the InGaAlN multilayer structures, wherein the passivation layer covers the sidewalls and bottom of the grooves

Methodology Applied

Scientific EffectPhysical vapor deposition: Physical Vapour Deposition

Implementation Method 2

depositing a passivation layer and an electrode layer above the InGaAlN multilayer structures

Methodology Applied

Scientific EffectPhysical vapor deposition: Physical Vapour Deposition

Implementation Method 3

creating conductive paths, which couple a predetermined number of adjacent individual LEDs, thereby allowing the LEDs to share a common power supply

Methodology Applied

Scientific EffectConduction: Conduction (electrical)

Data Source

PatentUS8044416B2Method for fabricating high-power light-emitting diode arrays

Publication Date: 2011.10.25 LATTICE POWER (JIANGXI) CORP

AI summary

One embodiment of the present invention provides a method for fabricating a high-power light-emitting diode (LED). The method includes etching grooves on a growth substrate, thereby forming mesas on the growth substrate. The method further includes fabricating indium gallium aluminum nitride (InGaAlN)-based LED multilayer structures on the mesas on the growth substrate, wherein a respective mesa supports a separate LED structure. In addition, the method includes bonding the multilayer structures to a conductive substrate. The method also includes removing the growth substrate. Furthermore, the method includes depositing a passivation layer and an electrode layer above the InGaAlN multilayer structures, wherein the passivation layer covers the sidewalls and bottom of the grooves. Moreover, the method includes creating conductive paths which couple a predetermined number of adjacent individual LEDs, thereby allowing the LEDs to share a common power supply and be powered simultaneously to form a high-power LED array.