Nano Lithography

Chapter 5

Patterning with Self-Assembling Block Copolymers ¹

5.1. Block copolymers: a nano-lithography technique for tomorrow?

Since 1960, the microelectronics industry has witnessed enormous progress focused essentially on the development and application of Metal Oxide Semiconductor (MOS) transistor technologies. Indeed, whereas in 1962 the first integrated circuit included two transistors, today the most powerful microprocessors are composed of several tens of millions of MOS transistors per chip (e.g. 42 million for Intel's Pentium 4). This rapid expansion of microelectronics is driven by the perpetual requirement to manage and store larger quantities of data on increasingly smaller supports, with less energy consumption. This incessant reduction of device dimensions will soon reach the limits of conventional fabrication processes and traditional technologies, such as optical lithography and etching, and will probably not be able to create high density objects of a size c.18 nm, the length predicted for transistors in 2018 [ITR 01]. In this context, the use of block copolymer (BCP) thin films seems to be a powerful alternative for quite specific applications to overcome the intrinsic limitations of traditional lithographic techniques. This technology, based on the self-organization of polymeric chains similar to conventional polymer photoresist chains used in semiconductor fabrication, allows the realization of regular patterns whose dimensions cannot be achieved by optical ...