GaN LED Substrate Removal via Stressor Spalling
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Solution Overview
Problem
GaN-based light-emitting diodes (LEDs) require expensive growth substrates, and existing methods for improving light intensity, such as distributed Bragg reflectors and substrate texturing, do not effectively address the cost and efficiency of substrate reuse and heat dissipation.
Innovation Solution
A method involving the formation of alternating material layers to create a reflector on the back side of the LED structure, deposition of a stressor layer, and adherence of a handle substrate, followed by a spalling process to separate the LED from the growth substrate, allowing for efficient substrate reuse and improved heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If distributed Bragg reflectors and substrate texturing are employed to improve light intensity, then light emission intensity is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The LED structure is divided into multiple functional layers including n-type and p-type semiconductor layers with alternating orientations, allowing each layer to be optimized independently for light emission while simplifying the overall manufacturing process
Solution Approach 2:
The patent transitions from conventional planar LED structures to vertically stacked three-dimensional structures with alternating layer orientations, enabling improved light extraction in the vertical dimension while maintaining manufacturing efficiency
2Duration of action of stationary object
If conventional LED structures are used, then manufacturing is simpler, but heat dissipation is insufficient and lifetime is reduced
Solution Approach 1:
Different regions of the LED structure have different orientations and properties - alternating n-type and p-type layers with perpendicular orientations create localized thermal pathways that improve heat dissipation from specific high-heat-generation regions
Solution Approach 2:
The LED employs composite semiconductor structures with alternating crystal orientations and doping types, creating a multi-phase material system that provides both optical functionality and enhanced thermal management through anisotropic heat conduction pathways
3Ease of manufacture
If substrate reuse is implemented, then cost is reduced, but manufacturing process complexity increases
Solution Approach 1:
The LED structure is designed with alternating layer orientations during the initial growth phase on the substrate, preparing the structure in advance for subsequent substrate removal and reuse, thereby simplifying the overall process despite the initial complexity
Solution Approach 2:
The substrate is temporarily used during LED fabrication, then deliberately removed and reused for subsequent LED structures, converting a consumable into a reusable component while maintaining manufacturing efficiency through standardized processes
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 enables the fabrication of high-quality LEDs with enhanced light emission and reduced substrate costs by employing a stressor layer for mechanical splitting, resulting in efficient substrate removal and improved thermal management.
Implementation Method 1
forming alternating material layers on an LED structure, formed on a substrate, to form a reflector on a back side opposite the substrate
Implementation Method 2
depositing a stressor layer on the reflector. A handle substrate is adhered to the stressor layer. The LED structure is separated from the substrate using a spalling process
Data Source
AI summary
A method for fabrication a light emitting diode (LED) includes forming alternating material layers on an LED structure, formed on a substrate, to form a reflector on a back side opposite the substrate. A handle substrate is adhered to a stressor layer deposited on the reflector. The LED structure is separated from the substrate using a spalling process to expose a front side of the LED structure.