LED Separation via Air Bridge Wet Etching
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Solution Overview
Problem
Existing methods for separating compound semiconductor layers, such as GaN, from growth substrates are time-consuming and economically unfavorable, especially for large area films, and can result in film damage due to high-energy laser processes or inefficient wet etching.
Innovation Solution
A method involving the formation of a patterned mask layer on a substrate, followed by the growth of a contact layer with air bridges, allowing for efficient separation of the LED structure from the growth substrate using a wet etch process, which expedites the separation and reduces waste by enabling the reuse of substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wet etching process is used to separate compound semiconductor layer from growth substrate, then separation can be achieved, but the process becomes very time-consuming for large area films
Solution Approach 1:
The patent introduces a sacrificial layer between the compound semiconductor layer and growth substrate before epitaxial growth. This sacrificial layer is specifically designed to be selectively removable, enabling rapid separation without time-consuming wet etching of the entire structure. The preliminary placement of this sacrificial interface allows for quick mechanical or chemical separation later in the process.
Solution Approach 2:
The sacrificial layer acts as an intermediary element between the compound semiconductor layer and the growth substrate. This intermediate layer facilitates easy separation by providing a predefined weak interface that can be selectively removed, avoiding the need for prolonged wet etching of the bonded structures.
2Productivity
If high-energy laser beam is used to separate GaN film from sapphire substrate, then separation can be achieved, but the GaN film may be blown away or fractured
Solution Approach 1:
The sacrificial layer serves as a protective intermediary that absorbs the separation energy mechanically rather than requiring high-energy laser irradiation. This intermediate structure enables separation through controlled removal of the sacrificial material, preventing direct thermal冲击 to the GaN film and avoiding blow-away or fracture effects.
Solution Approach 2:
The patent replaces the optical-mechanical separation method (laser-induced stress) with a chemical or mechanical removal process targeting the sacrificial layer. This substitution eliminates the harmful high-energy laser interaction with the GaN film while achieving the same separation objective through selective sacrificial layer removal.
3Ease of manufacture
If conventional separation methods are used, then separation can be achieved, but substrate reuse is limited increasing costs
Solution Approach 1:
The patent extracts the compound semiconductor layer from the growth substrate through the sacrificial layer interface, allowing the growth substrate to remain intact and reusable. The sacrificial layer is selectively removed while leaving both the substrate and semiconductor layer undamaged, enabling substrate reuse for subsequent growth cycles.
Solution Approach 2:
The sacrificial layer is designed to be the disposable element in the separation process. After serving its purpose of enabling easy separation, it is selectively removed and discarded, while the expensive growth substrate and compound semiconductor layer are recovered intact for reuse in subsequent manufacturing cycles.
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 method significantly reduces the time and cost associated with separating large area films while minimizing damage, allowing for the efficient production of light-emitting diodes by facilitating the detachment of the LED structure from the growth substrate through air bridges that enhance the etching process.
Implementation Method 1
it is separated from its growth substrate by a wet etching process, which selectively etches away the sacrificial layer
Implementation Method 2
The resultant structure is then irradiated from the sapphire side with an intense laser beam. The intense heating of the GaN separates the gallium from gaseous nitrogen
Implementation Method 3
The intense heating of the GaN separates the gallium from gaseous nitrogen, thereby separating the GaN thin film from the sapphire substrate
Data Source
AI summary
A method of forming a light-emitting diode (LED) device and separating the LED device from a growth substrate is provided. The LED device is formed by forming an LED structure over a growth substrate. The method includes forming and patterning a mask layer on the growth substrate. A first contact layer is formed over the patterned mask layer with an air bridge between the first contact layer and the patterned mask layer. The first contact layer may be a contact layer of the LED structure. After the formation of the LED structure, the growth substrate is detached from the LED structure along the air bridge.