Integration of SiCN as a low κ etch stop and Cu passivation in a high performance Cu/low κ interconnect

Abstract

This paper describes the integration of a silicon carbon nitride (SiCN) copper passivation and etch stop layer into a Cu low k dielectric interconnect technology. The incorporation of SiCN improves interconnect performance by virtue of its lower dielectric constant as compared to silicon nitride, and through changes to the process integration made possible by the improved etch selectivity and good copper interface properties.

Low‐kMaterials: Recent Advances

“…The first interface results from the ILD deposition on a capping layer, which serves to protect the underlying copper metal (see Figure 1.3 (a) ). Capping layers composed of SiN x , SiC x N y and SiC x are commonly employed and present surface chemistries considerably different from those based on SiO x [21][22][23][24][25]. Coupled with the fact that adhesive properties scale inversely with porosity [26,27], this combination may lead to severe delamination during chemical-mechanical polishing (CMP) and chip-package interaction (CPI).…”

Study of electromigration-induced voiding mechanisms in Cu interconnects

“…Electromigration mechanisms in Cu and issues with damascene interconnect structures are also being studied but conflicting results are reported and electromigration mechanism in dual-damascene interconnects is not studied in depth [1]. The problem of electromigration is further perplexed by the introduction of new low-k materials having significantly different thermo-mechanical properties than conventional SiC>2 dielectric [12][13][14][15][16][17][18][19][20]. The fundamental electromigration-induced voiding mechanism in Cu damascene needs to be understood to address these issues.…”

Investigating the electromigration reliability of copper interconnects

“…Cu interconnects have the lowest activation energy for interface diffusion, with the interface between the dielectric cap and the Cu conductive line serving as the fast diffusion path [15,23]. Efforts on Cu surface modification include surface treatments after and/or surface coating before dielectric cap deposition and the use of different dielectric-cap layers such as SiN x , SiNC and variants thereof [24][25][26][27][28][29]. Although some initial efforts in this field are emerging in electromigration, the effects of these changes and a change of dielectric cap composition on electromigration are still of great importance.…”

“…If we take Z eJ e=30* 1.6* 10'19 C and Cu resistivity p=l. 7*10-8 Q'm, then the electron force during one atom jump is approximately 2.5 xlO'29 J. Therefore, the function of thermal gradient is at least four orders of magnitude lower than that of electron wind force.…”