Atomic Layer Deposition of the Solid Electrolyte LiPON for 3D solid state nanobatteries

Since its discovery in the early 1990s, LiPON (lithium phosphorus oxynitride) has been one of the most popular solid state electrolytes used for planar lithium ion microbatteries. University of Maryland demonstrate an ALD process for the solid electrolyte lithium phosphorousoxynitride (LiPON) using lithium tert-butoxide (LiOtBu), H2O, trimethylphosphate (TMP), and plasma N2 (PN2) as precursors using av Ultratech / Cambridge Naotech Fiji 200 PEALD reactor. The results are published in the Open Access article below.

ANSLab at the University of Maryland. Shown, from left to right, is a Cambridge Nanotech Fiji F200 ALD Tool (Luigi), a glovebox for working with air-sensitive materials, a rotary wafer transporter (R2P2), thermal evaporation chamber, and second Cambridge Nanotech Fiji F200 ALD tool (Mario). (source: http://www.terpconnect.umd.edu/~ackozen/Research.html)

Atomic Layer Deposition of the Solid Electrolyte LiPON (OPEN ACCESS)

Alexander C. Kozen, Alexander J. Pearse, Chuan-Fu Lin, Malachi Noked, and Gary W. Rubloff

Chem. Mater., Article ASAP
DOI: 10.1021/acs.chemmater.5b01654

We demonstrate an atomic layer deposition (ALD) process for the solid electrolyte lithium phosphorousoxynitride (LiPON) using lithium tert-butoxide (LiOtBu), H2O, trimethylphosphate (TMP), and plasma N2 (PN2) as precursors. We use in-situ spectroscopic ellipsometry to determine growth rates for process optimization to design a rational, quaternary precursor ALD process where only certain substrate–precursor chemical reactions are favorable. We demonstrate via in-situ XPS tunable nitrogen incorporation into the films by variation of the PN2dose and find that ALD films over approximately 4.5% nitrogen are amorphous, whereas LiPON ALD films with less than 4.5% nitrogen are polycrystalline. Finally, we characterize the ionic conductivity of the ALD films as a function of nitrogen content and demonstrate their functionality on a model battery electrode—a Si anode on a Cu current collector.