The development of flexible integrated circuits based on thin-film transistors

The use of thin-film transistors in liquid crystal display applications was commercialized about 30 years ago. The key advantages of thin-film transistor technologies compared with traditional silicon CMOS (complementary metal-oxide-semiconductor) transistors are their ability to be manufactured on large substrates at a low-cost per unit area and at low processing temperatures, which allows the transistors to be directly integrated onto a variety of flexible substrates. Here, I discuss the potential of thin-film transistor technologies in the development of low-cost, flexible integrated circuits for applications beyond flat-panel displays, including the Internet-of-Things and lightweight wearable electronics. Focusing on the relatively mature thin-film transistor technologies that are available in semiconductor fabrication plants today, the different technologies are evaluated in terms of their potential circuit applications and the implications they will have in the design of integrated circuits, from basic logic gates to more complex digital and analogue systems. I also discuss microprocessors and non-silicon, near-field communication (NFC) tags that can communicate to smartphones, and I propose the concept of a Moore’s law for flexible electronics.