Directed Self-Assembly of Lamellar Copolymers: Effects of Interfacial Interactions on Domain Shape

Abstract

The depth-dependent structure of a poly(styreneb-methylmethacrylate) (PS-PMMA) line grating (46 nm pitch) was calculated from quantitative analysis of small-angle X-ray scattering profiles. These data demonstrate that domain shapes are significantly deformed near the substrate interface, where the local PS domain shape resembles an hourglass. The bulk equilibrium dimension is recovered near the center of a 64 nm thick film. Simulations based on self-consistent field theory suggest that deformations near the substrate are caused by extensive penetration of the copolymer domains into the underlying substrate coating (a PS-brush). These findings suggest that new coatings for block copolymer directed self-assembly should consider copolymer penetration lengths in addition to tailoring surface energetics. Furthermore, given the resolution and ensemble-averaging features of synchrotron X-ray scattering, we argue that it has the potential to emerge as a "gold-standard" or "benchmark" dimensional metrology and library validation tool for high density, sub-10 nm features.

Metabolic response of perfused livers to various oxygenation conditions

“…If a higher beam energy were used, then the silicon substrate would have greater transparency and the sampled film volume would increase, thereby improving the signal‐to‐noise. In such a case, the higher‐order CTRs could be detected, so one could measure the depth‐dependent shape of the domains 42…”

“…The in‐plane ordering of perpendicular cylinders and lamellae has been studied extensively,18, 19 and it is known that thermally generated dislocations and disclinations disrupt the lateral correlation lengths 20–23. These in‐plane defects can be minimized through techniques such as shear alignment,24, 25 zone refinement,26–31 graphoepitaxy,32–35 and chemical epitaxy 36–42. Out‐of‐plane defects can distort the size, shape, and positions of desired features,43, 44 so it is important to develop quantitative methods of characterization.…”

“…Out‐of‐plane defects can distort the size, shape, and positions of desired features,43, 44 so it is important to develop quantitative methods of characterization. As shown by several literature studies, X‐ray and neutron scattering techniques can detect relevant characteristics such as depth‐dependent lateral order,45–48 out‐of‐plane domain orientation distributions,12, 49–51 and depth‐dependent domain shape 42…”

Effect of chemoepitaxial guiding underlayer design on the pattern quality and shape of aligned lamellae for fabrication of line-space patterns

“…14 The lamellae need to also form as straight vertically as possible in order to form a proper mask for the anisotropic etch or ion implantation, therefore it is important that during microphase separation no footing of the lamellae should occur, though little work has been done to explore the footing and undercutting of lines. While some work has been done to explore footing due to the geometry of a chemical pattern with no density multiplication, 15,16 this paper seeks to explore the effects varying parameters in a density doubling underlayer (2x density multiplication) has on line quality, both in terms of roughness and footing. The parameters to be explored include the composition of the background region and the width of the pinning stripe.…”

Research Updates: The three M's (materials, metrology, and modeling) together pave the path to future nanoelectronic technologies

“…101 The latter is more challenging due to the sensitivity of polymers to charge based imaging techniques and weak x-ray scattering due to the low electron density of carbon. 102 Adoption of DSA will also ultimately require efficient models that can readily enable design of device components and circuit layout to be directly translated into DSA derived structures and ultimately predict device performance and defect formation. 96 Focusing strictly on metrology, the recent transition to 3D transistor and interconnect structures implies the need for metrologies capable of measuring critical dimensions and detecting defects in 3D nanoscale features.…”