GaN-on-Glass Micro LED Display with Buffer Layers
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Solution Overview
Problem
The high manufacturing cost of micro LED display devices is attributed to the expensive process of transferring LED chips, and the difficulty in forming gallium nitride-based transistors and light emitting diodes on amorphous glass substrates due to the high temperature requirements of sapphire substrates.
Innovation Solution
A display device configuration that includes a transistor and a light emitting diode with gallium nitride layers formed over an amorphous glass substrate using a sputtering method with titanium or aluminum nitride buffer layers, allowing for low-temperature crystal growth and electrical connection between the transistor and light emitting diode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If gallium nitride layers are formed on sapphire substrates using MOCVD or HVPE, then high crystallinity and proper crystal orientation are achieved, but the manufacturing cost increases and the substrate temperature must be maintained at 800-1000 degrees
Solution Approach 1:
The patent introduces a buffer layer as an intermediary between the amorphous glass substrate and the gallium nitride layer. This buffer layer enables low-temperature formation of high-quality gallium nitride crystals on cost-effective amorphous glass substrates, eliminating the need for expensive sapphire substrates and high-temperature MOCVD/HVPE processes while maintaining proper crystal orientation and reducing manufacturing costs
Solution Approach 2:
The patent changes the substrate material from sapphire to amorphous glass and reduces the formation temperature from 800-1000 degrees to lower temperatures using sputtering method. By adjusting the buffer layer composition and using alternative deposition techniques, the patent achieves proper crystal orientation and high crystallinity under milder conditions, reducing both cost and energy consumption
2Ease of manufacture
If gallium nitride layers are formed on amorphous glass substrates using sputtering method, then manufacturing cost is reduced, but achieving high crystallinity and proper crystal orientation becomes difficult
Solution Approach 1:
The buffer layer serves as a critical intermediary that mediates between the amorphous glass substrate and the gallium nitride layer. It provides a crystalline template that guides the formation of high-quality gallium nitride crystals during low-temperature sputtering, enabling proper crystal orientation and high crystallinity to be achieved on cost-effective amorphous glass substrates
Solution Approach 2:
The patent replaces the high-temperature MOCVD or HVPE processes with the sputtering method for forming gallium nitride layers on amorphous glass substrates. By using sputtering with a carefully designed buffer layer, the patent achieves comparable or superior crystallinity at lower temperatures, reducing manufacturing complexity and cost
3Reliability
If micro LED display devices are manufactured by transferring LED chips to backplanes, then high efficiency and high brightness are achieved, but the manufacturing cost increases due to the expensive transfer process
Solution Approach 1:
The patent merges the transistor and light emitting diode formation processes into a single integrated manufacturing flow on the same amorphous glass substrate. Both components are formed using the same low-temperature sputtering method and buffer layer approach, eliminating the need for separate chip transfer processes and reducing manufacturing cost while maintaining high efficiency and brightness
Solution Approach 2:
The patent develops a universal manufacturing approach using sputtering with buffer layers that can form both transistors and light emitting diodes on amorphous glass substrates. This multi-functional process eliminates the need for specialized high-temperature equipment and chip transfer operations, providing a cost-effective method for manufacturing micro LED display devices with high efficiency
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 reduces manufacturing costs by enabling the formation of gallium nitride-based components on large-sized amorphous glass substrates, maintaining proper crystallinity and facilitating electrical connectivity, thus providing a cost-effective and efficient method for producing micro LED display devices.
Implementation Method 1
a gallium nitride layer formed over the buffer layer
Data Source
AI summary
A display device includes an amorphous glass substrate, a first buffer layer on a first surface of the amorphous glass substrate, a transistor including a first gallium nitride layer over the first buffer layer, a second buffer layer on the first surface of the amorphous glass substrate, and a light emitting diode including a second gallium nitride layer over the second buffer layer. The transistor and the light emitting diode are electrically connected to each other.