Comparison of Self-Assembled Monolayers on SiO2 and Porous SiOCH Dielectrics by Decyltrimethoxysilane Vapor Treatment

Abstract

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.

Comparison of Self-Assembled Monolayers Using 3-Aminopropyltrimethoxysilane and Decyltrimethoxysilane in Vapor Phase for Porous SiOCH Dielectrics

“…For the pristine p-SiOCH film, Si-O-Si stretching, Si-CH3 bending, and CHx stretching modes, which are located at the wavenumbers of 1030, 1250, and 2850 cm −1 , respectively, are the main peaks [22,23]. The broad Si-O-Si stretching peak in the p-SiOCH film was attributed to the overlap of three types of Si-O-Si stretching mode (network, suboxide, cage) [19]. The FTIR spectra in Figure 1 shows that after APTMS or DTMOS treatment, a broad peak in the 3100-3500 cm −1 region, attributed to adsorbed water induced by O2 plasma irradiation, showed a decreased intensity.…”

“…The backbone, which is typically a hydrocarbon-based chain, provides Van der Waals forces to form a well-ordered molecular layer and controls the thickness of SAMs. The terminal group reacts with the upper substrate to form a strong chemical bonding [14][15][16][17][18][19].…”