Fabrication and characterization of entirely inkjet-printed polysilicon thin film transistors

Abstract

In this paper, the fabrication and material innovation involved in the first and only entirely inkjet-printed polysilicon thin film transistors (TFTs) are described. To form TFT layers, five inkjet printing inks were developed with the goal of fabricating TFTs by using purely additive processing without vacuum deposition or conventional lithography. A silicon ink was developed to form both the channels and polysilicon gates, and boron and phosphorus dopant inks were developed for N+ and P+ doping. In addition, a silver nanoparticle (NP) ink was developed to form interconnect traces, and a palladium chloride ink was formulated to create palladium silicide for the ohmic contacts between the source and the drain. The first N-type metal-oxide-semiconductor (MOS) polysilicon TFT was fabricated with a top-gate self-alignment scheme. This exhibited a mobility of approximately 80 cm2 V s−1. Next, P-type MOS transistors as well as complementary MOS devices were also successfully fabricated.

Large‐area, high‐temperature stainless steel foil substrate for manufacturing low‐cost and flexible CMOS polysilicon TFTs

“…To fabricate low-cost TFTs, we made years of effort to use solution process and demonstrated fully ink-jet printed polysilicon TFTs with the highest mobility among all ink-jet printed TFTs. 9 What we also learned was that when using any current printing technique, it is not possible to fabricate polysilicon TFTs which meet specification of our products and customer requirements which need 4-/8-μm dimension TFTs with LTPS level mobility. We concluded it is necessary to take hybrid process as intermediate step to move to volume production of this performance of TFTs for low-cost and volume application soon.…”

Optimizing Aerosol Jet Printing Process of Platinum Ink for High-Resolution Conductive Microstructures on Ceramic and Polymer Substrates

“…In recent years, printing processes have gained interest as a means of making costeffective electronic circuits and devices [1,2]. The most known traditional printing processes are lithography, etching, and sputtering [3,4].…”

Formulation and characterization of screen printable dopant ink for fabrication of polysilicon TFTs

“…For example, entirely ink-jet printed CMOS TFTs on silicon wafers using poly-hydrosilane ink for active layers and polygate implementations were developed. Novel inks compatible with inkjet printing were also developed for N+ and P+ dopants, silicide contacts, and silver interconnects [1]. However, the industrial inkjet printing technology proved immature due to jet inconsistency which drove up maintenance and slowed production.…”