LED Matrix Display Manufacturing with Low-Temperature Hybridization
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Solution Overview
Problem
Existing methods for manufacturing high-luminance microscreen display devices using LEDs expose the LED matrix to high temperatures, leading to alignment and connection challenges during the transfer and hybridization of electronic control circuits, and are hindered by materials with different thermal expansion coefficients.
Innovation Solution
A method involving the production of a matrix of LEDs with electrodes on the rear face and light-emitting surfaces on the front face, where a stack of semiconductor, gate dielectric, and conductive gate material layers is joined to form FET transistors, allowing for precise alignment and production of high-density electronic control circuits without exposing the LEDs to high temperatures, using advanced lithography and direct bonding techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional processes for producing transistors with large thermal budgets are used, then the electronic control circuit achieves required performance, but the matrix of LEDs is exposed to excessively high temperatures
Solution Approach 1:
The manufacturing process is divided into two separate stages: first producing the LED matrix at low temperatures, then producing the electronic control circuit at high temperatures on a separate substrate. This segmentation allows each component to be manufactured under optimal temperature conditions without compromising the other.
Solution Approach 2:
A separate substrate is introduced as an intermediary carrier for the electronic control circuit. This substrate allows high-temperature processing of transistors to occur independently, then enables transfer of the completed circuit to the LED matrix substrate through hybridization techniques, protecting the LEDs from thermal damage.
2Illumination intensity
If transfer and hybridization of electronic control circuit on matrix of LEDs is carried out via micro-tubes, then high-luminance microscreen can be produced, but alignment precision of less than 1 μm is required making the process complex
Solution Approach 1:
The electronic control circuit is extracted from the LED matrix production process and manufactured separately on its own substrate. This extraction eliminates the need for complex alignment and connection processes through micro-tubes, while still enabling the production of high-luminance microscreens through subsequent hybridization.
3Reliability
If hybridization is carried out at temperature greater than approximately 100° C., then electronic control circuit can be coupled to matrix of LEDs, but differences in thermal expansion coefficient cause alignment shift and thermal stress leading to substrate rupture
Solution Approach 1:
The electronic control circuit is completely fabricated on its substrate before hybridization, including all high-temperature processing steps. This preliminary action allows the circuit substrate to be pre-stressed and stabilized, reducing thermal expansion mismatches during subsequent low-temperature hybridization with the LED matrix.
Data Source
Figure 1A~1D
Figure 1E~1G
Figure 2A~2C
AI summary
Method for making a display device (1000), comprising at least the implementation of the following steps: - making an LED matrix (100) each having electrodes accessible from a rear face of the LED matrix and light-emitting surfaces from a front face of the LED matrix; - attaching, on the rear face of the LED matrix, a stack of layers comprising at least one semiconductor layer, one gate dielectric layer and one gate conductive material layer; - making, from the stack of layers, an electronic control circuit electrically coupled to the LED electrodes, comprising making FET transistors whose active areas (216) are formed in the semiconductor layer and whose gates (224) are formed in the gate dielectric and gate conductive material layers.