Direct patterning of low-dielectric constant (low-k) materials via nanoimprint lithography (NIL) has the potential to
simplify fabrication processes and significantly reduce the manufacturing costs for semiconductor devices. We report
direct imprinting of sub-100 nm features into a high modulus methylsilsesquioxane-based organosilicate glass (OSG)
material. An excellent fidelity of the pattern transfer process is quantified with nm precision using critical dimension
small angle X-ray scattering (CD-SAXS) and specular X-ray reflectivity (SXR). X-ray porosimetry (XRP) and positron
annihilation lifetime spectroscopy (PALS) measurements indicate that imprinting increases the inherent microporosity of
the methylsilsequioxane-based OSG material. When a porogen (pore generating material) is added, imprinting decreases
the population of mesopores associated with the porogen while retaining the enhanced microporosity. The net effect is a
decrease the pore interconnectivity. There is also evidence for a sealing effect that is interpreted as an imprint induced
dense skin at the surface of the porous pattern.
Directly patterning dielectric insulator materials for semiconductor devices via nanoimprint lithography has the
potential to simplify fabrication processes and reduce manufacturing costs. However, the prospect of mechanically
forming these materials, especially when they are highly porous, raises concerns about their physical integrity. We
report the direct imprinting of 100 nm parallel line-space patterns into a high modulus poly(methylsilsesquioxane)-based
organosilicate thin film that is capable, in its non-patterned form, of meeting the ultra-low dielectric constant
requirement of k ≈ 2.3. Immediately after imprinting a (5 to 10) % shrinkage in the pattern height of the partially
vitrified patterns relative to the mold is quantified using X-ray reflectivity. Nanoscopic pores with an average diameter
of approximately 2.2 nm are then generated in the patterns at high temperatures, through the volatilization a second
phase porogen, while the material simultaneously vitrifies into a glassy organosilicate network. Pattern shape changes
upon vitrification are also quntified and indicating that a 12 % reduction in the pattern height of the porogen-loaded
imprint is observed with very little change in the pattern width. For a imprint without the added porogen, the shrinkage
is still anisotropic in the height direction, but reduced approximately by 4 %. Our results show that nanoporous low-k
patterns can be replicated via nanoimprint lithography with very little loss in the pattern quality.
This paper describes the first logical approach to the design of chemical amplification resists that are stable toward airborne contamination. This molecular design is based on the observation that uptake of N-methylpyrrolidone (NMP) by thin polymer films is primarily governed by glass transition temperatures (Tg) of the polymers. This concept has led to the design of environmentally very robust chemical amplification resists that provide positive images upon development with aqueous base.
Jerome Swalen, Gary Bjorklund, Stephen Ducharme, William Fleming, Stephan Herminghaus, Dietmar Jungbauer, William Moerner, Barton Smith, Robert Twieg, Do Yoon, C. Grant Willson
Increased interest and activity in optoelectronics has resulted from anticipated applications
of optics to communication, electronic interconnections, information storage and possibly
even logic. Current nonlinear optical (NLO) devices today employ inorganic crystals, such
as lithium niobate for electrooptic modulation and switching and KDP or KNbO3 for
frequency doubling. Organic nonlinear optical materials, that is, poled organic polymeric
films and organic crystals, have the potential to replace some of these inorganic crystals.1
Key advantages include the high intrinsic nonlinearities of some organic molecules, the
ability to optimize the molecular structure for specific applications, low dc dielectric
constant, and low temperature processing. Current progress has also been made in
improving the long term stability of these materials. Here we wish to report on some of our
recent results on measurements of the order parameter, new crosslinked polymeric
materials which exhibit more stability and some device applications with polymeric
materials and organic crystals.
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