Enhanced Ti0.84Ta0.16N diffusion barriers, grown by a hybrid sputtering technique with no substrate heating, between Si(001) wafers and Cu overlayers

Marlene Mühlbacher; Grzegorz Greczynski; Bernhard Sartory; Nina Schalk; Jun Lu; Ivan Petrov; J E Greene; Lars Hultman; Christian Mitterer

doi:10.1038/s41598-018-23782-9

Enhanced Ti_0.84Ta_0.16N diffusion barriers, grown by a hybrid sputtering technique with no substrate heating, between Si(001) wafers and Cu overlayers

Sci Rep. 2018 Mar 29;8(1):5360. doi: 10.1038/s41598-018-23782-9.

Authors

Marlene Mühlbacher^{1

2

3}, Grzegorz Greczynski⁴, Bernhard Sartory⁵, Nina Schalk⁶, Jun Lu⁴, Ivan Petrov^{4

7}, J E Greene^{4

7}, Lars Hultman⁴, Christian Mitterer⁶

Affiliations

¹ Department of Physical Metallurgy and Materials Testing, Montanuniversität Leoben, Franz-Josef-Strasse 18, A-8700, Leoben, Austria. marlene.muehlbacher@unileoben.ac.at.
² Thin Film Physics Division, Department of Physics, Chemistry, and Biology (IFM), Linköping University, S-581 83, Linköping, Sweden. marlene.muehlbacher@unileoben.ac.at.
³ Department of Materials Physics, Montanuniversität Leoben, Franz-Josef-Strasse 18, A-8700, Leoben, Austria. marlene.muehlbacher@unileoben.ac.at.
⁴ Thin Film Physics Division, Department of Physics, Chemistry, and Biology (IFM), Linköping University, S-581 83, Linköping, Sweden.
⁵ Materials Center Leoben Forschung GmbH, Roseggerstrasse 12, A-8700, Leoben, Austria.
⁶ Department of Physical Metallurgy and Materials Testing, Montanuniversität Leoben, Franz-Josef-Strasse 18, A-8700, Leoben, Austria.
⁷ Department of Materials Science, Physics, and the Frederick Seitz Materials Research Laboratory, University of Illinois, Urbana, Illinois, 61801, USA.

Abstract

We compare the performance of conventional DC magnetron sputter-deposited (DCMS) TiN diffusion barriers between Cu overlayers and Si(001) substrates with Ti_0.84Ta_0.16N barriers grown by hybrid DCMS/high-power impulse magnetron sputtering (HiPIMS) with substrate bias synchronized to the metal-rich portion of each pulse. DCMS power is applied to a Ti target, and HiPIMS applied to Ta. No external substrate heating is used in either the DCMS or hybrid DCMS/HiPIMS process in order to meet future industrial thermal-budget requirements. Barrier efficiency in inhibiting Cu diffusion into Si(001) while annealing for 1 hour at temperatures between 700 and 900 °C is investigated using scanning electron microscopy, X-ray diffraction, four-point-probe sheet resistance measurements, transmission electron microscopy, and energy-dispersive X-ray spectroscopy profiling. Ti_0.84Ta_0.16N barriers are shown to prevent large-scale Cu diffusion at temperatures up to 900 °C, while conventional TiN barriers fail at ≤700 °C. The improved performance of the Ti_0.84Ta_0.16N barrier is due to film densification resulting from HiPIMS pulsed irradiation of the growing film with synchronized Ta ions. The heavy ion bombardment dynamically enhances near-surface atomic mixing during barrier-layer deposition.