Nickel Germanide Thin Films by Atomic Layer Deposition

Abstract

This work presents preparation of nickel germanide (Ni 2 Ge) thin films by atomic layer deposition (ALD). The films were grown using NiCl 2 (tmpda) (tmpda = N,N,N′,N′,-tetramethyl-1,3-propanediamine) and tributylgermanium hydride serving as a new, efficient reducing agent. This is the first time ALD Ni x Ge y films are prepared directly upon the combination of two precursors and without any annealing treatment. Ni x Ge y is an important contact material for enabling Ge-based transistors and thus circumventing the scaling issues related to current microelectronics. The Ni 2 Ge process was examined at low temperatures of 160−200 °C. Self-limiting, saturative growth with a high growth rate of 0.91 Å/cycle was observed at 180 °C. The films were thoroughly analyzed in terms of morphology, crystallinity, composition, and resistivity. The Ni 2 Ge films were pure, with the sum of contaminants being less than 1 at. %. Owing to their high purity, the films exhibited low resistivity, suggesting suitability for contact applications.

A low-temperature thermal ALD process for nickel utilizing dichlorobis(triethylphosphine)nickel(ii) and 1,4-bis(trimethylgermyl)-1,4-dihydropyrazine

“…NiCl 2 (tmpda) sublimes cleanly at 160 -180 °C / 0.5 mbar and withstands temperatures up to 250 °C. 24 As compared with other known Ni and Co precursors, this volatility is among average. However, especially when elemental metal films are to be deposited, the volatility should be as high as possible to enable lowest possible deposition temperature to minimize agglomeration for getting smoother films, and thereby continuous films at lower thickness.…”

“…Earlier we have introduced diamine adducts of nickel and cobalt halides as cost effective precursors to ALD. 18,19,23,24 Nickel and cobalt halides as such are solids with polymeric structures and poor volatility. Sublimation temperatures above 350 °C are typically needed.…”

Facile Access to an Active γ‐NiOOH Electrocatalyst for Durable Water Oxidation Derived From an Intermetallic Nickel Germanide Precursor

“…Among the existing NiGe x phases, nickel monogermanide (NiGe) has been regarded as a highly promising material due to its low electric resistivity (metallic property), enhanced stability in a wide temperature range, low‐temperature synthetic approach, and facile chemical processing [11] . Thus, it is the most favored contact material in complementary to metal‐oxide‐semiconductor devices [10a,d, 12] . Until now, however, the synthesis of NiGe nanomaterials is challenging and has been rarely reported [10b] .…”

“…[9] Intermetallic nickel phases such as nickel germanides are an important class of metal semiconductors that are wellknown for their high thermal stability as well as their applications in the areas of microelectronics,p hotovoltaics, magnetism, and thermoelectrics. [10] Among the existing NiGe x phases,n ickel monogermanide (NiGe) has been regarded as ah ighly promising material due to its low electric resistivity (metallic property), enhanced stability in awide temperature range,low-temperature synthetic approach, and facile chemical processing. [11] Thus,itisthe most favored contact material in complementary to metal-oxide-semiconductor devices.…”

Thermal Chemistry of Nickel Diketonate Atomic Layer Deposition (ALD) Precursors on Tantalum and Silicon Oxide Surfaces

“…Being a chemistry-based technique, ALD requires the use of appropriate chemicals. − For the deposition of nickel, many metal organic compounds have been tested, including nickel tetracarbonyl (Ni­(CO) 4 ), nickel cyclopentadienyls such as bis­(cyclopentadienyl)nickel (NiCp 2 ), − bis­(methylcyclopentadienyl)­nickel (Ni­(MeCp) 2 ]), − bis­(ethylcyclopentadienyl)­nickel (Ni­(EtCp) 2 ), , and (η 3 -cyclohexenyl)­(η 5 -cyclopentadienyl)nickel (Ni­(Chex)­(Cp)]), nickel diamines such as NiCl 2 ( N , N , N ′, N ′,-tetramethyl-1,3-propanediamine) (NiCl 2 (TMPDA)), , diazadienyls such as bis­(1,4-diisopropyl-1,3-diazabutadienyl)­nickel (Ni­( i Pr-DAD) 2 ) and bis­(1,4-di- tert -butyl-1,3-diazabutadienyl)nickel (Ni­( t But-DAD) 2 ), − nickel acetamidinates such as bis­( N , N ′-diisopropylacetamidinato)nickel (Ni­( i Pr-amd) 2 ) and bis­( N , N ′-di- tert -butylacetamidinato)­nickel (Ni­( t But-amd) 2 ), − β-diketonates such as bis­(acetylacetonate)nickel (Ni­(acac) 2 ) − and bis­(2,2,6,6-tetramethyl-3,5-heptanedionate)nickel (Ni­(TMHD) 2 , or Ni­(thd) 2 ), − mixed nickel diamine-diketonates such as ( N , N , N ′, N ′-tetramethylethylenediamine)­(bis­(2,4-pentanedionato)­nickel (Ni­(acac) 2 (tmeda)), , and nickel amino-alkoxides such as bis­(1-dimethylamino-2-methyl-2-butoxide)nickel (Ni­(dmamb) 2 ). − …”