Atomic Layer Deposition of Ruthenium Thin Films for Copper Glue Layer

Abstract

Ruthenium thin films were produced by atomic layer deposition ͑ALD͒ using an alternating supply of bis͑ethylcyclopentadi-enyl͒ruthenium ͓Ru(EtCp) 2 ͔ and oxygen at a deposition temperature of 270°C. The relative ratio of the Ru(EtCp) 2 adsorbed on the film surface to the oxygen partial pressure in the following oxygen pulse determines whether Ru or RuO 2 film was obtained. At the range with higher relative ratio the film was composed of ruthenium, but the film deposited at the lower range was revealed to be ruthenium oxide. In case of the ruthenium thin film, the film thickness per cycle was saturated at 0.15 nm/cycle, and its resistivity was about 15 ⍀ cm. The impurities of carbon and oxygen were incorporated into the film with less than 2 atom %. It was also demonstrated that the ruthenium thin films prepared by ALD can be used as an excellent glue layer to improve the interfacial adhesion of metallorganic chemical vapor deposited copper to TiN. Secondary ion mass spectroscopy analysis showed that the ruthenium glue layer suppressed the interfacial contaminants, such as carbon and fluorine, which originated from the metallorganic precursors of copper.

Atomic Layer Deposition of Ruthenium Thin Films from an Amidinate Precursor

“…[2] Ru has a conductive oxide, RuO 2 , which makes it an ideal substrate for oxide dielectrics deposited with ozone, such as rutile phase TiO 2 . [3] Ru thin films have been deposited by both physical vapor deposition and chemical vapor deposition.…”

“…The cyclopentadienyl (Cp) compounds, such as RuCp 2 and Ru(EtCp) 2 , [2,4,5] and the tris--diketonates (thd) compounds, such as Ru(thd) 3 , [6] have been studied with O 2 as co-reactant. The ruthenium amidinate precursor, bis(N,N'-di-tert-butylacetamidinato)ruthenium(II) dicarbonyl, has been synthesized in our group and used to deposit ruthenium thin films with or without NH 3 as co-reactant.…”

Smooth, Low-Resistance, Pinhole-Free, Conformal Ruthenium Films by Pulsed Chemical Vapor Deposition

“…3 Ru can also be used as a seed layer for electrodeposition of copper interconnects. 4 Many chemical processes use ruthenium as a catalyst. 5 Preparing thin Ru films with good properties, such as high density, low resistivity, and pinhole-free smooth surfaces, has raised much interest in industry recently.…”

Synthesis and Characterization of Ruthenium Amidinate Complexes as Precursors for Vapor Deposition

“…They are basically divided into *Address correspondence to these authors at the Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA; E-mail: Gordon@chemistry.harvard.edu two categories: ruthenium organometallic compounds containing Ru-C bonds such as Ru 3 (CO) 12 [10] and ruthenocenes [11,12] such as Ru(Cp) 2 and Ru(EtCp) 2 [13] (Cp = cyclopentadienyl); and ruthenium -diketonates [14] or Ru(CO) 2 ( -diketonates) 2 [15]. These precursors lack sufficient reactivity with common second reactants such as hydrogen, water, and ammonia.…”