Next-generation lithography for 22 and 16 nm technology nodes and beyond

Abstract

In this paper, next-generation lithography (NGL) for the 22 and 16 nm technology nodes and beyond is reviewed. A broad range of topics, including history, technologies, critical challenges, and the most plausible candidates are discussed. The 22 and 16 nm technology nodes rely on NGL. NGLs have been extensively studied. Because of technological issues, the semiconductor industry has stopped pursuing several NGLs, such as X-ray proximity lithography, ion projection lithography, and scattering with angular limitation projection electron lithography. Currently, the primary candidate technologies are extreme ultraviolet lithography (EUVL), maskless lithography (ML2), and nanoimprint lithography (NIL), with EUVL being the leading candidate. Since EUVL was first proposed in 1988, many studies have been conducted. Currently, there is no "show stopper" for EUVL. Moreover, challenges are present in almost all aspects of EUVL technology. Almost all primary semiconductor manufacturing companies plan to implement commercial pre-production step-and-scan exposure tools in 2011. However, EUVL power at an intermediate focusing level has not yet met the volume manufacturing requirements. EUVL resists have been significantly improved recently, but there is still a critical need to meet requirements on resolution, line width roughness, and sensitivity. Creating a defect-free EUVL mask is another obstacle to the application of EUVL. ML2 and NIL, like EUVL, have also undergone significant progress recently, but throughput, defect control, and cost remain the critical impediments for practical application.

Efficient light confinement with nanostructured optical microfiber tips

“…Finally, another important application is the diagnosis of defects. In fact, at the moment, there are no ways to investigate defects with size smaller than 22 nm [58,59].…”

Sub-20 nm laser ablation for lithographic dry development

“…Tanaka et al showed that capillary forces during the drying of developed patterns cause collapse, as indicated by line bending, breaking, and loss of adhesion [1]. Since this initial finding, pattern collapse has been noted as one of the critical hurdles for reaching 16 nm nodes and beyond in microelectronics [2]. Researchers have tried to reduce pattern collapse via surfactants [3][4][5][6], surface modifiers [7], alternative drying solvents [8], modulus increase [9] and mechanical supports [10].…”

Ultra-sensitive EUV resists based on acid-catalyzed polymer backbone breaking

“…The development of exposure tools that have ever-shorter wavelengths constitutes one of the major trends in lithography, in the effort of achieving mass production of devices with sub-20nm and even sub-10nm feature sizes. In this context, extreme UV lithography (EUVL) at a wavelength of 13.5nm is the main candidate for nextgeneration lithography technology [1][2][3]. However, EUV lithography requires high-performance photoresists with high sensitivity (<20mJ/cm 2 ) to enable high throughput in high volume manufacturing environment.…”