ONGOING RESEARCH
Design and synthesis of sustainable dielectric materials for flexible electronics (01/01/2021-12/31/2024)
Flexible electronic materials exhibiting high electrical and mechanical performance are required in the emerging field of flexible devices. There are many potential materials which are required in the fabrication of flexible electronics. These materials range from organic materials, like polymers and other carbon-based molecules, to metals and dielectrics. Among them, the use of dielectric materials has been restricted due to limiting electrical properties and insufficient mechanical durability. The research here establishes highly transparent, strong, and flexible dielectric materials developed through the understanding of the relationship between the physicochemical structure of the dielectric thin films, and their other material properties, under mechanical stress. These flexible dielectric materials would find use in the existing semiconductor device manufacturing as well as in future, more demanding applications.
Dual-sintering with thermal annealing and laser irradiation for copper nanoparticles structures fabrication (08/15/2022-08/14/2023)
The goal of this project is to fabricate an additive conducting copper (Cu) structures with improved structural and mechanical stability.
Laser-assisted thermal sintering of metal nanoparticles for the fabrication of consolidated metallic patterns and structures (01/01/2022-12/31/2022)
The goal of this project is to establish an additive conducting patterns and structures with improved electrical and mechanical stability. First, printing variables for uniform and consistent patterns are determined for desired shape and thickness. Second, the optimized thermal sintering conditions are adopted with carboxylic acids. Third, laser irradiation is applied before or after thermal sintering. Laser irradiation conditions including power, speed, and time affect the sinterability. The results of laser-assisted thermal sintering will be compared to those of one-step sintering between thermal and laser sintering. Highly reliable and stable conducting patterns by the optimized sintering process using additional laser irradiation are a great potential in the additive manufacturing.
Effect of thermal annealing environment on microstructure evolution and material performance of additive metallic nanostructures, LA EPSCoR SURE (01/01/2022-12/31/2022)
Additive metallic nanostructures are constructed by thermal annealing of deposited metal nanoparticles (NPs). Thermal annealing results in an agglomeration and grain growth of metal NPs and thus densification of microstructures. To reinforce the additive structures for a wide range of applications, the mechanical strength should be secured. To enhance the mechanical properties, dense microstructures without defects or voids are required. Annealing conditions including temperature, time, atmosphere, and pressure significantly impact on the microstructure evolution. The goal of the project is to build additive metallic structures with enhanced mechanical performance. The overall objective is to obtain densified metallic nanostructures for high mechanical strength using an optimized thermal annealing condition
Dielectric failure and recovery mechanisms in flexible electronics (06/01/2020-06/30/2023)
As the device features of integrated circuits (ICs) continue to shrink, the RC delay associated with the resistance (R) and the capacitance (C) between the wires is the dominant factor for its performance and reliability. To reduce the RC delay, it is necessary to replace the present interlayer dielectric silicon oxide (dielectric constant, k ~ 4.1), with low-k materials (k ≤ 3.5). Various low-k materials have been developed for existing semiconductor device fabrication. Meanwhile, a variety of flexible electronic devices will be common in everyday use in the near future, like recently released foldable smartphone and rollable TV/display. Flexible electronic materials exhibiting high electrical and mechanical performance are required in the emerging field of flexible electronics. Among flexible electronic materials, flexible high-k (k > 7) materials have been developed with polymers. However, the wide applications of high-k materials are restricted due to their limiting electrical properties and mechanical durability. Moreover, little research has been conducted for flexible low-k materials. In this project, carbon-doped oxide (CDO) films, SixOyHz(CH3)u with the stoichiometry (x:y:z:u), are introduced as flexible and transparent low-k materials, which have excellent optical/electrical/mechanical stability.
PRIOR PROJECT
Sintering mechanism of silver nanoparticles under unique atmosphere using carboxylic acids (01/01/2021-12/31/2021)
The goal of this project is to establish printed Ag NP patterns with high electrical and mechanical performance for broad applications in additive manufacturing. Ag NP inks are used to print patterns with desired shape and thickness and subjected to a sintering process, which removes organic compounds and aids in the consolidation of NPs. The sintering process with carboxylic acid vapors is introduced in order to remove organic moieties effectively, to connect NPs, and to give electrical conductance in the printed Ag patterns.
Metal patterns with a desired thickness from metal nanoparticles for RFID tags (01/01/2020-01/31/2021)
The objective of this project is to develop optimized printing and sintering techniques to fabricate printed electronic devices such as RFID tags and electrical circuits. The proposed research is composed of three procedures: (1) Design material composition and select adequate reducing agents, (2) Fabricate conductive patterns with various shapes and a desired thickness, and (3) Integrate RFID tags or other electrical circuits on flexible substrates.
Development of multiple printed metal layers from the optimized sintering of metal NPs for the fabrication of electrodes, interconnects, or circuits (01/01/2019-12/31/2019)
Metal NPs have attracted significant attention in the fabrication of electrodes or interconnects in various electronic devices. The metal NPs patterns for electrodes, interconnects, or circuits by printing of inks or pastes are subjected to thermal processing. Thermal processing or so-called sintering is an essential process which helps metal NPs bond and agglomerate for improvement of film compaction and transforms a nonconductive printed pattern to a conductive one. The objective of this project is to develop multiple printed metal layers from the optimized sintering of metal NPs for the fabrication of electrodes, interconnects, or circuits. Well established sintering process of multiple printed patterns enable the fabrication of electrical circuits with the desired thickness and improved electrical/mechanical performance.