Three-terminal transistor printing via inverted electrode contact
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Solution Overview
Problem
Current methods fail to effectively design and interconnect microscopic 3-terminal devices, such as transistors, for printing due to difficulties in achieving proper orientation and making electrical contacts, leading to poor performance in printed circuits.
Innovation Solution
A semiconductor wafer is formed with 3-terminal devices having a bottom, top, and intermediate electrode, which are singulated and mixed into a solution to be printed on a substrate, allowing for self-planarization and connection of electrodes in parallel, ensuring proper orientation and electrical contact through multiple conductor layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If 3-terminal devices are printed using conventional 2-terminal LED printing methods, then the printing process can be simplified, but the devices cannot be properly interconnected because the electrodes are oriented incorrectly and cannot make proper electrical contact
Solution Approach 1:
The patent inverts the conventional approach by printing the intermediate conductor layer first, then printing the devices so that their electrodes contact this pre-formed layer. This reversal allows the intermediate electrode to make proper contact with the intermediate conductor layer, enabling correct interconnection of 3-terminal devices while maintaining a simplified printing process.
Solution Approach 2:
The patent introduces a third conductor layer dimension between the top and bottom electrodes, creating a multi-layer conductor structure. This dimensional addition enables proper interconnection of all three terminals (top, intermediate, bottom) by allowing each electrode to contact its corresponding conductor layer in parallel, solving the interconnection problem while maintaining manufacturing simplicity.
2Reliability
If multiple conductor layers are added to enable proper electrode contact, then electrical contact reliability improves, but device complexity increases
Solution Approach 1:
The patent segments the conductor structure into three distinct parallel layers (top, intermediate, bottom conductor layers), each dedicated to contacting a specific electrode. This segmentation simplifies the design by assigning each conductor layer a specific function, making the multi-layer structure manageable and enabling reliable electrical contact without excessive complexity.
Solution Approach 2:
The intermediate conductor layer serves multiple functions: it contacts the intermediate electrode, provides a conductive path between top and bottom circuits, and enables proper orientation of the 3-terminal devices. This multi-functionality reduces overall system complexity by combining several roles into a single layer.
3Manufacturing precision
If devices are printed in a monolayer with self-planarization, then manufacturing precision improves, but the ability to ensure proper electrode orientation and contact becomes more difficult
Solution Approach 1:
The patent performs preliminary action by pre-forming the intermediate conductor layer before printing the devices. This allows the intermediate electrode to automatically contact the pre-positioned conductor layer during the self-planarization process, ensuring reliable electrical contact while maintaining the benefits of monolayer printing precision.
Solution Approach 2:
The patent utilizes the self-planarization property of the printed ink to automatically ensure proper electrode-conductor contact. The ink's surface tension and flow characteristics cause it to self-level and fill gaps, making the devices self-align with the conductor layers without requiring additional alignment steps, thus maintaining manufacturing precision while ensuring contact reliability.
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 efficient printing of 3-terminal devices in a monolayer with high orientation accuracy, allowing for the formation of complex circuits like logic gates and flash memory arrays with improved reliability and performance.
Implementation Method 1
The ink is then printed on the substrate and self-planarizes by surface tension so that the layer does not cover any features above the thickness of the layer.
Implementation Method 2
The solvent is then evaporated by heat using, for example, an infrared oven.
Data Source
AI summary
A layer of microscopic, 3-terminal transistors is printed over a first conductor layer so that bottom electrodes of the transistors electrically contact the first conductor layer. A first dielectric layer overlies the first conductor layer, and a second conductor layer over the first dielectric layer contacts intermediate electrodes on the transistors between the bottom electrodes and top electrodes. A second dielectric layer overlies the second conductor layer, and a third conductor layer over the second dielectric layer contacts the top electrodes. The devices are thus electrically connected in parallel by a combination of the first conductor layer, the second conductor layer, and the third conductor layer. Separate groups of the devices may be interconnected to form more complex circuits. The resulting circuit may be a very thin flex-circuit.