Asymmetric fluid-structure dynamics in nanoscale imprint lithography

understanding of the interaction between the fluid-solid interface will be essentialfor the practical development of the SFIL process.1.2 OPTICAL LITHOGRAPHYHistorically, the manufacture of microelectronic devices has utilizedoptical lithography. The processing technologies have evolved over the past fourdecades, moving from 20 µm to 130 nm minimum feature sizes, and are wellestablished in the semiconductor industry. Thus far, the progress in opticallithography has been made primarily through the exploitation of shorterwavelength exposing sources. These have included lines from the emissionspectrum of different light sources: the g-line (mercury-xenon arc lamp, λ ≈ 436nm), the i-line (mercury-xenon, λ ≈ 365 nm), and deep ultraviolet (kryptonfluorideexcimer laser, DUV, λ ≈ 248 nm), etc. Electron beam exposure systemshave been successfully used in specialized applications to pattern micro andnanoscale features while x-ray (λ ~ 1 nm) and ion beam exposure systems havedemonstrated fine feature capability. However, each of these approaches haveproved inferior to optical lithography since they have either lower throughput,higher mask complexity and costs, higher tools costs, etc.The basic scheme of optical lithography is to replicate two-dimensionalpatterns from a master pattern on a durable photomask, typically made of a thinpatterned layer of chromium on a quartz plate [Sheats and Smith 1998]. Thepatterns are developed on semiconductor wafer substrates using photosensitiveresist material, complex projection optics systems, and chemical etch/depositionprocesses. The next section gives a brief summary of the optical lithographyprocess. Then, some of the limitations of optical lithography are discussed.3