Abstract
In this work, we have demonstrated chemically coupled (3-aminopropyl)trimethoxysilane (APTMS) and 3-mercaptopropionic acid (MPA) self-assembled monolayers (SAMs) to enhance the diffusion barrier properties against copper (Cu) as well as the adhesion properties towards SiO2 and Cu electrode. The coupled-SAM (C-SAM) can attach to both Cu and SiO2 strongly which is expected to enhance both the diffusion barrier and adhesion properties. A carbodiimide-mediated amidation process was used to link NH2 terminated APTMS to COOH terminated MPA. The resulting C-SAM shows a low root-mean-square roughness of 0.44 nm and a thickness of 2 nm. Time-dependent dielectric breakdown (TDDB) tests are used to evaluate APTMS and C-SAM for their ability to block Cu ion diffusion. The average time-tofailure (TTF) is enhanced over 4 times after the MPA attachment, and is even comparable to TaN barriers. Capacitance-voltage (C-V) measurements are also conducted to monitor Cu ion diffusion. Negligible change in the flatband voltage and C-V curve is observed during the constant voltage stress C-V measurement. Enhancement of the adhesion properties are measured using four-point bending tests and shows that the C-SAM has a 33% enhancement in the adhesion properties between SiO2 and Cu compared to APTMS. The C-SAM shows potential as an ultra-thin Cu diffusion barrier which also has good adhesion properties.
Original language | English |
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Pages (from-to) | 60123-60130 |
Number of pages | 8 |
Journal | RSC Advances |
Volume | 4 |
Issue number | 104 |
DOIs | |
State | Published - 2014 |