Solution-based fabrication promises to be an inexpensive and effective means of producing integrated circuits on flexible substrates for a variety of applications, since it will allow the use of ultra low cost printing-based fabrication methods. In order to develop a successful solution-based manufacturing technology, we need access to materials analogous to soluble conductors, dielectrics, and semiconductors. In this project, we are developing a library of such materials, and applying them to various device and circuit architectures. Conductors are a necessary element for device contacts, interconnects, capacitor plates, and inductive elements. We form highly conductive films from solutions that can be deposited on a variety of materials. In order to achieve this we have taken advantage of the low anneal temperatures associated with nano-crystals. We have already developed ink-jet printable gold nano-crystals that, upon anneal at 120 C, result in extremely low-resistance conductive films. We have also developed novel syntheses for silver and copper nano-crystals to be used in similar applications.
Development of suitable dielectrics is another key challenge to the solution-based manufacturing of devices and circuits. Both high-K and low-K dielectrics are needed for device gating and passivation respectively. We are currently developing novel, solution-based materials for the formation of Hafnium, Zirconium, Titanium, and Aluminum oxides as high-K dielectrics, and polyimide-based passivation dielectrics.
The development of a soluble high-performance semiconducting material is perhaps one of the greatest challenges facing the solution-based manufacturing of circuits. Prompted by recent efforts in the field, we are exploring the development of a soluble precursor of pentacene . This modified pentacene molecule is soluble in a variety of solvents, and efficiently converts to pentacene, itself, upon mild heating. We have already manufactured organic FETs using these molecules and are in the process of further enhancing this technology.