The refractive-index contrast in dielectric multilayer structures, optical resonators, and photonic crystals is an important figure of merit that creates a strong demand for high-quality thin films with a low refractive index. A SiO2 nanorod layer with low refractive index of n = 1.08, to our knowledge the lowest ever reported in thin-film materials, is grown by oblique-angle electron-beam deposition of SiO2. A single-pair distributed Bragg reflector employing a SiO2 nanorod layer is demonstrated to have enhanced reflectivity, showing the great potential of low-refractive-index films for applications in photonic structures and devices.

In this paper, a method for the plasma-enhanced (PE) atomic layer deposition (ALD) of palladium on air-exposed, annealed poly(p-xylylene) (Parylene-N, or PPX) is presented. Palladium is successfully deposited on PPX at 80°C using a remote, inductively coupled, hydrogen/nitrogen plasma with palladium (II) hexafluoroacetylacetonate (Pd II (hfac) 2 ) as the precursor. By optimizing the mixture of hydrogen and nitrogen, the polymer surface is modified to introduce active sites allowing the chemisorption of the Pd II (hfac) 2 . In addition, enough free hydrogen atoms are available at the surface for ligand removal and Pd reduction, while at the same time, enough hydrogen atoms are consumed in the plasma to ensure there is no visible degradation of the PPX. X-ray photoelectron spectroscopy (XPS) measurements of the substrate after hydrogen/nitrogen plasma treatment at 50 W clearly show the presence of nitrogen bound to the substrate surface. XPS measurements of the deposited Pd films indicate good quality for both substrates, suggesting that the substrate temperature was low enough to prevent dissociation of the hfac ligand and adequate scavenging of the hfac ligand by the available atomic hydrogen. The remote hydrogen/nitrogen plasma enables Pd film deposition on polymer surfaces, which do not typically react with the Pd precursor, and are not catalysts for the dissociation of molecular hydrogen.

The introduction of porosity in dielectrics is desirable to reduce the dielectric constant; but it causes integration problems such as CVD/ALD precursor penetration for barrier layer/seed layer deposition. CVD Parylene-N has been shown to work as a pore sealant for porous low-materials but penetrates itself slightly into porous dielectric. The depth profile of Parylene-N in porous MSQ can be obtained using the Nuclear Reaction Analysis ͑NRA͒ of 12 C. The penetration of Parylene-N can be controlled by deposition at higher pressure where the deposition rate is also high. High deposition rate can also be attained by adding a carrier gas which also shows low Parylene-N penetration. The experimentally measured dielectric constants, after pore sealing, are compared to those calculated using the NRA data of Parylene-N penetration.

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Copper shows a tendency to drift into contiguous dielectric material under bias and temperature stressing. The stability of different compositions ͑by changing silane gas flow rate͒ of Ti-Si-N-O films has been investigated using metal-oxide-semiconductor ͑MOS͒ capacitors. MOS samples preannealed at 250°C and subjected to bias temperature stressing ͑BTS͒ at 150°C, 200°C under an electrical field of 0.5 or 1 MV/cm show stable capacitance-voltage behavior with no flatband voltage shift from as-annealed to 90 min of BTS for Ti-Si-N-O film with Si/Ti ratio of 0.48. The lack of flatband voltage shift indicates that Ti-Si-N-O film is able to prevent Cu ion penetration. It is found that the electrical stability of Ti-Si-N-O film is reduced with higher Si/Ti ratio. For Ti-Si-N-O film with Si/Ti ratio of 0.91, flatband voltage shifts 0.75 V after 90 min of BTS at 150°C and 0.5 MV/cm, and this shift is attributed to the interface states at the Ti-Si-N-O/oxide interface that were generated during the plasma process and could not be fully healed after 250°C annealing. Thus, it is suggested that with low silane gas flow rate, an electrically stable Ti-Si-N-O film can be achieved with fewer interface states.The implementation of copper in back-end-of-line metallization yields advantages such as low electrical resistivity, superior resistance to electromigration, and faster signal speed. However, copper in comparison to aluminum has a higher tendency to drift into interlevel dielectric as well as into the silicon substrate in the presence of an electrical field even at low temperature, 1-4 resulting in a degradation of the electrical properties. Thus, a barrier layer is required between Cu/dielectric for reliable integration.Various refractory metals and their nitrides have been heavily examined as barrier materials. For example, TaN has been recognized as one of the most promising diffusion barriers for copper due to its high thermal stability, chemical inactivity with Cu, 5,6 and no intermetallic formation at elevated temperatures. 5 Besides TaN, extensive work in the deposition of TiN by both sputtering 7,8 and chemical vapor deposition 9,10 has been reported. A common denominator underlying many of the above references is the columnar structure of TiN, typically with a ͑111͒ or ͑200͒ preferred orientation. Such a structure can lead to short-circuit diffusion paths via grain boundaries and result in the failure of the devices. With the downscaling of devices and more stringent reliability requirements, there is a need for more effective barrier materials. To this end, a class of refractory ternary nitrides, such as Ti-Si-N, Ta-Si-N, and W-Si-N, has been proposed as candidates for the next-generation diffusion barrier in copper/low-k dielectric back-end-of-line device fabrication. 11,12 Various research groups have explored the formation of ternary nitride films by physical vapor deposition ͑PVD͒, metallorganic chemical vapor deposition, and metallorganic atomic layer deposition techniques, documenting their resulting electric...