Mark F. Roll

para-Octaiodophenylsilsesquioxane, [p-IC6H4SiO1.5]8, a Nearly Perfect Nano-Building Block

The cubic symmetry of octafunctional octaphenylsilsesquioxanes [ROPS, (RC6H4SiO(1.5))8] coupled with a 1 nm diameter offers exceptional potential to assemble materials in three dimensions with perfect control of periodicity and the potential to tailor global properties at nanometer length scales. OPS itself is very inert and insoluble and can only be functionalized via electrophilic reactions with difficulty and with poor substitutional selectivity. However, functionalized OPS products are robust and highly soluble, offering easy purification and processing. In contrast to previous studies, we report here that OPS reacts with ICl at sub-ambient temperatures to provide (following recrystallization) [p-IC6H4SiO(1.5)]8, or I8OPS, in good yields and with excellent selectivity: >99% mono-iodo substitution with >93% para substitution as determined by H2O2/F- cleavage of the Si-C bonds to produce iodophenols. I8OPS in turn can be functionalized using conventional catalytic coupling reactions to provide sets of >93% para-substituted, functionalized compounds (alkynes, alkenes, aryl amines, phosphonates, aryl amines, polyaromatics, etc.), suggesting the potential to develop diverse nano-building blocks for the assembly of a wide variety of materials, some with novel photonic, electronic, and structural properties.

Polyoxometalate Hybrid Nano-Building Blocks for Extreme Ultra-Violet Photoresists

Extreme Ultra-violet Lithography (EUVL), regardless of some setbacks, has continued its push as a viable option for next generation nodes of photolithography. Utilizing a 13.5nm wavelength, EUV is still showing promise as a natural progression of optical lithography in the semiconductor industry. Despite this upside, EUVL also has its drawbacks, one of which includes the development of a suitable photoresist material. The development and characterization of polyoxometalate (POM) hybrid nano-building blocks (NBBs) shows great potential as a candidate for improving the patterning of semiconductor devices using EUVL. Octamolybdate macromolecules were synthesized using literature methods. These primary materials were modified for improvements using a combination of physical mixtures with photoacids (resist sensitivity) and epoxide (mechanical stability). In addition, tellurium atoms (EUV absorption) were incorporated chemically and will be explored with similar mixtures to better understand the relatively limited knowledge of POM materials as functional photoresists and dielectric materials.

An Investigation of Polyoxometalate Hybrid Materials as Patternable Dielectrics and Lithographic Resists

Polyoxometalate (POM) hybrid materials have shown potential as spin-coatable, patternable dielectric thin-films and components for lithographic resists. In particular, the octamolybdate cluster has been shown to possess good spin-coating properties and the patterning capabilities of hybrid octamolybdate thin-films were explored using a combination of broadband UV and electron beam lithography (EBL) techiniques. Dielectric properties of these films were determined by ellipsometry, and octamolybdate clusters were subsequently investigated as negative resists in various blends for potential uses in next-generation photolithography, where contrast, sensitivity, and line edge roughness characteristics were determined. Preliminary evidence for the suppression of the diffusion of photo-generated acids is presented.

Refractory Thin‐Films Derived from Organometallic Polymers

Refractory materials are critical for the ultra-high temperature environments that are encountered in diverse settings, from turbine blades to the leading edges of objects travelling at hypersonic speeds through the atmosphere, such as railgun projectiles or reentry craft. Hafnium carbide and hafnium diboride are refractory materials with melting points in excess of 3200°C. Our goal is to develop a versatile polymer precursor-based route to produce hafnium carbide and hafnium diboride using reductive techniques to couple haloform monomers and oxidative methods to couple borohydride monomers. The flexibility of the system we describe will also enable us to produce hafnium carbide and tantalum carbide solid solutions, which possess the highest reported melting point of any refractory, >4200°C. Critically, these polymeric precursors will provide potential pathway for producing conformal, thin and thick films suitable for the leading edges of hypersonic projectiles or reentry craft.