In this study, the reliability characteristics of metal-insulator-semiconductor (MIS) capacitor structures with low-dielectric-constant (low-k) materials have been investigated in terms of metal gate area and geometry and thickness of dielectric film effects. Two low-k materials, dense and porous low-k films, were used. Experimental results indicated that the porous low-k films had shorter breakdown times, lower Weibull slope parameters and electric field acceleration factors, and weaker thickness-dependence breakdowns compared to the dense low-k films. Additionally, a larger derivation in dielectric breakdown projection model and a single Weilbull plot of the breakdown time distributions from various areas merging was observed. This study also pointed out that the porous low-k film in the irregular-shaped metal gate MIS capacitor had a larger dielectric breakdown time than that in the square- and circle-shaped samples, which violates the trend of the sustained electric field. As a result, another breakdown mechanism exists in the irregular-shaped sample, which is required to explore in the future work.

The electrical and reliability characteristics of CuSc layer on SiO 2 film are reported. In an integrated CuSc/SiO 2 structure, a selfforming barrier (SFB) was formed at the interface by thermal annealing at 425 °C. After annealing, electrical characteristics, electromigration, and time-dependent-dielectric-breakdown reliability were improved due to the formation of SFB. This shows that CuSc has great potential as a liner-and barrier-free interconnect material.

Self-assembled monolayers (SAMs) are emerging as materials that are candidates of barriers used in back-end-of–line interconnects of integrated circuits for future generations. In this study, SAMs were formed on the SiO2 and porous SiOCH (p-SiOCH) films by using decyltrimethoxysilane (DTMOS) precursor in vapor phase at a temperature of 100 °C. The effects of the formation of SAMs at the surfaces of SiO2 and p-SiOCH films on the electrical characteristics were characterized and compared. With O2 plasma irradiation, SAMs could successfully form on both SiO2 and p-SiOCH films, thereby enhancing the adhesion and dielectric breakdown field. In the p-SiOCH films, SAMs sealed the surface pores and had higher coverage, promoting the effectiveness of the Cu barrier. In the Cu/porous low-k integrated interconnects for advanced technological nodes, therefore, SAMs are promising emerging materials acting as a barrier and adhesive. On the other hand, for SiO2 films, SAMs weakened the barrier; however, they can act as an interfacial adhesion enhancer.

In this study, Cu-2.2 at. % Nd alloy films using a co-sputtering deposition method were directly deposited onto porous low-dielectric-constant (low-k) films (SiOCH). The effects of CuNd alloy film on the electrical properties and reliability of porous low-k dielectric films were studied. The electrical characteristics and reliability of the porous low-k dielectric film with CuNd alloy film were enhanced by annealing at 425 • C. The formation of self-forming barrier at the CuNd/SiOCH interface was responsible for this improvement. Therefore, integration with CuNd and porous low-k dielectric is a promising process for advanced Cu interconnects.

Silicon carbonitride (SiCN) films deposited using silazane singe-precursor with different temperatures were capped onto porous carbon-doped silicon oxide (p-SiOCH) dielectric films. Effects on the electrical and reliability characteristics of the fabricated SiCN/p-SiOCH stacked dielectrics were investigated. Experimental results indicated that increasing the deposition temperature of the SiCN film increased barrier capacity against Cu migration under thermal and electrical stress and time-dependence-dielectric-breakdown reliability for the SiCN/p-SiOCH stacked dielectric. Therefore, this study provides a promising processing to deposit a SiCN barrier by elevating the deposition temperature and using N-methyl-aza-2,2,4-trimethylsilacyclopentane singe-precursor, which can be applied to back-end-of-line interconnects for advanced technological nodes in the semiconductor industry. A larger capacitance, however, is the main issue due to a larger intrinsic dielectric constant of the SiCN film and stronger plasma-induced damage on the p-SiOCH film. As a result, the related actions will be taken in the future research to improve this issue.