Direct-liquid-evaporation chemical vapor deposition of smooth, highly conformal cobalt and cobalt nitride thin films

Abstract

By a direct-liquid-evaporation chemical vapor deposition (DLE-CVD) method, we deposited smooth low-resistance cobalt (Co) and cobalt nitride (CoxN) thin films with excellent conformality at low temperatures down to 200 °C.

Direct-Liquid-Evaporation Chemical Vapor Deposition of Nanocrystalline Cobalt Metal for Nanoscale Copper Interconnect Encapsulation

“…In all depositions, co-reactant gas flows are set to be 100 sccm NH 3 and 100 sccm H 2 , and the precursor solution concentration is fixed at 12 wt%, which were evaluated to be the best conditions for high conformality and smoothness according to our previous report. 23 microelectronics. 7 By plotting the natural logarithm of growth rate versus the reciprocal of temperature (Figure 2b), we calculated the activation energies of Co deposition processes with different precursor flow rates based on the Arrhenius' equation.…”

“…Those results reveal that our DLE-CVD Co film is a mixed phase of fcc-Co and hcp Co, which is in accordance with our previous report. 23 It is our hypothesis that the competing growth between hcp and fcc induced lattice frustration and suppressed the growth of larger crystals, producing nanocrystalline films, which are favorable for Cu liner/capping applications. [35][36] Based on the Co-Cu phase diagram, Co and Cu do not diffuse into each other at temperatures below 700 K, and only partially intermix at temperatures up to 1000 K from the thermodynamic point of view.…”

“…23,26 Tetradecane (Millipore Sigma Chemical Co.) was distilled from sodium to remove moisture before use. All chemical operations were conducted in a glove box with a nitrogen atmosphere.…”

“…21 Recently, our group reported novel direct-liquid-evaporation chemical vapor deposition (DLE-CVD) methods for metal and metal nitride thin films, which provided the feasibility to create higher-quality Co films over a wide range of deposition temperatures and low chance of pre-deposition decomposition of precursors. [22][23] When a precursor is vaporized from a conventional bubbler, the actual rate of vapor delivery is subject to many variables, including drifts in the bubbler temperature, the amount of precursor remaining in the bubbler, and thermal decomposition during long times at high temperatures. In contrast, precursors in DLE-CVD systems are stored at room temperature, so that thermallyinduced decomposition is negligible.…”

Pure and conformal CVD nickel and nickel monosilicide in high-aspect-ratio structures analyzed by atom probe tomography

“…DLE provides a higher vapor pressure of precursors, which is needed to deposit highly conformal CVD films inside high-aspect-ratio features. 15 Moreover, the precursor delivery rate of DLE-CVD is controlled by the very stable injection rate of a liquid precursor or a precursor solution, instead of the variable precursor vapor pressure found in conventional bubblers. 16 These features of DLE-CVD enable formation of films with much higher conformality and better reproducibility.…”