Tailoring the Crystallographic Texture and Electrical Properties of Inkjet-printed Interconnects for Use in Microelectronics

Abstract

In this paper, silver nanoparticles with a mean diameter of 40 nm are studied for future applications in microelectronic devices. The enhanced diffusivity of nanoparticles is exploited to fabricate electrical interconnects at low temperature. Sintering condition has been tuned to tailor the grain size so that electrical resistivity can be lowered down to 3.4 µOhm•cm. In this study, a {111}-textured gold thin film has been used to increase diffusion routes. The combined effects of the substrate crystalline orientation and the sintering condition have been demonstrated to have a significant impact on microstructures. In particular, a {111} fiber texture is developed above 300°C in printed silver only if the underlying film exhibits a preferential orientation. This condition appeared as essential for the efficiency of the gold wire-bonding process step. Thus, inkjet-printed interconnects show a prospective potential compared to conventional subtractive technique and offers new opportunities for low cost metallization in electronics packaging.

Crystallographic Orientation Analysis of Nanocrystalline Tungsten Thin Film Using TEM Precession Electron Diffraction and SEM Transmission Kikuchi Diffraction

“…W is preferred as a metal interconnect because it exhibits outstanding properties such as the highest melting point and the lowest thermal expansion among other candidate metals (Dellasega et al, 2012; Girault et al, 2013). The properties of W thin film, such as resistivity (Steinhögl et al, 2005), thermal conductance (Han et al, 2017), electromigration and diffusivity (Cauchois et al, 2012; Liu et al, 2014), as well as mechanical properties (Girault et al, 2013), are known to be inextricably meshed with their grain size, grain structure, and crystallographic orientation (Shen et al, 2000; El-Atwani et al, 2015) and are usually impaired by a reduction in the characteristic size, as device sizes continuously scale down. In particular, as grain boundaries critically affect the electron mobility, the nature of the misorientation and grain boundaries in nanocrystalline W thin films needs to be characterized quantitatively to ensure excellent circuit performance (Musil et al, 1995; Steinhögl et al, 2005).…”

Impact of variable frequency microwave and rapid thermal sintering on microstructure of inkjet-printed silver nanoparticles

“…While densification usually tends to involve bulk diffusion routes, non-densifying surface diffusions mechanisms are easily activated by temperature. 7111 Previous results have been reported on the impact of sintering temperature and time on the final microstructure of silver nanoparticles [9,10]. In this study, fast sintering techniques are explored for low temperature initiation of densifying regimes.…”