Doped Ru to enable next generation barrier-less interconnect

An effective method for the formation of a Zn-doped Ru liner is demonstrated that realizes a self-forming barrier to achieve low resistivity interconnects for future back-end of line interconnect nodes. The “Ru–Zn” exhibits significantly improved adhesion to the dielectric and better electrochemical nucleation as compared to those of pristine Ru. In addition, time-dependent dielectric breakdown (TDDB) measurements indicate the inhibition of Cu ions drifting into the dielectric that precedes the TDDB failure. Complementary analysis using x-ray absorption spectroscopy, transmission electron microscope, and energy dispersive spectroscope suggests that the “Ru–Zn” forms an interfacial Zn–Si–O compound, and Zn, being more electronegative than Cu, protects the latter from oxidation. Calculation using density function theory also indicates that the Zn–Si–O compound adopts an intercalated structure at the interface of Ru/dielectric in which Zn occupies the interstitial sites within the Si–O lattice. We propose a twofold mechanism for improved TDDB performance: (1) the intercalated Zn atoms effectively block the diffusion of Cu ions through the dielectric and (2) Zn provides the cathodic protection of Cu that prevents the generation of mobile Cu ions that accelerate the TDDB.

[1]  C. Pao,et al.  Editors' Choice—Interface Engineering Strategy Utilizing Electrochemical ALD of Cu-Zn for Enabling Metallization of Sub-10 nm Semiconductor Device Nodes , 2019, ECS Journal of Solid State Science and Technology.

[2]  K. Laasonen,et al.  Atomic Layer Deposition of Zinc Oxide: Diethyl Zinc Reactions and Surface Saturation from First Principles , 2016 .

[3]  S. Bent,et al.  ALD of Ultrathin Ternary Oxide Electrocatalysts for Water Splitting , 2015 .

[4]  A. Genç,et al.  Electrical and reliability characterization of CuMn self forming barrier interconnects on low-k CDO dielectrics , 2012 .

[5]  S. Bent,et al.  Nanoengineering and interfacial engineering of photovoltaics by atomic layer deposition. , 2011, Nanoscale.

[6]  Yun-Hee Lee,et al.  Combined Rietveld refinement of Zn2SiO4:Mn2+ using X-ray and neutron powder diffraction data , 2010 .

[7]  Daniel Josell,et al.  Size-Dependent Resistivity in Nanoscale Interconnects , 2009 .

[8]  M. Mitrić,et al.  Optical and structural properties of Zn2SiO4:Mn2+ green phosphor nanoparticles obtained by a polymer-assisted sol–gel method , 2008 .

[9]  J. Koike,et al.  Growth behavior of self-formed barrier at Cu–Mn∕SiO2 interface at 250–450°C , 2007 .

[10]  C. Cabral,et al.  On the use of alloying elements for Cu interconnect applications , 2006 .

[11]  Junichi Koike,et al.  Self-forming diffusion barrier layer in Cu–Mn alloy metallization , 2005 .

[12]  B. Nagabhushana,et al.  Solution combustion derived nanocrystalline Zn(2)SiO(4):Mn phosphors: a spectroscopic view. , 2004, The Journal of chemical physics.

[13]  Panayotis C. Andricacos,et al.  Damascene copper electroplating for chip interconnections , 1998, IBM J. Res. Dev..

[14]  G. Kresse,et al.  Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set , 1996 .

[15]  J. Cheon,et al.  Chemical vapor deposition of zinc from diallyl zinc precursors , 1994 .

[16]  K. Croes,et al.  Current Understanding of BEOL TDDB Lifetime Models , 2015 .