Low-Temperature Deposition of Conformal Copper Films in Supercritical CO₂by Catalytic Hydrogen Reduction of Copper Hexafluoroacetylacetonate

Abstract

Conformal copper films were deposited onto various copper diffusion barrier layers with catalytic hydrogen reduction of copper(II) hexafluoroacetylacetonate, Cu(hfa)2, in supercritical CO2. In the presence of 2−5 at. % of Pd(hfa)2 (relative to Cu(hfa)2), device quality copper films (resistivity 2.1 × 10-6 Ω-cm) could be obtained at temperatures as low as 70 °C. The amounts of Pd in the Cu films were found to be very low (∼0.2 at. %) throughout the bulk of the Cu films. Adhesion of Cu films onto barrier layers was strong despite no Cu seed layer being used. The bottom-up supercritical fluid deposition mechanism allowed Cu films to fill up small features patterned on Si wafers.

One-Step Fabrication of Copper Thin Films on Insulators Using Supercritical Fluid Deposition

“…The liquid-like density enables dissolution of various metal organic compounds and thereby enables deposition of metals and metal oxides at relatively high precursor concentrations. [21][22][23][24][25][26][27][28][29][30][31][32][33] This concentrated supply allows surface saturation of the precursors on the growing surface, causing non-linear reaction kinetics known as Langmuir-Hinshelwood (LH) kinetics, where the growth rate is nearly independent of the precursor concentration. Accordingly, SCFD achieves a constant rez E-mail: momo@dpe.mm.t.u-tokyo.ac.jp action rate even at the bottom of HAR features as long as the precursor concentration is high enough.…”

Diffusion Barriers

“…In addition, advanced techniques based on supercritical fluid deposition [12], growth of self-assembled monolayers or barrier-free metallization [13] are evaluated. An important criterion for utilizing these techniques in volume manufacturing is the number of necessary process steps.…”

Supercritical-carbon dioxide-assisted cyclic deposition of metal oxide and metal thin films

“…[1][2][3][4] Most previous work from supercritical CO 2 ͑sc CO 2 ͒ has been performed in a continuous growth mode ͑analogous to chemical vapor deposition͒ where all precursors are introduced simultaneously to the reactor cell. [1][2][3][4] Most previous work from supercritical CO 2 ͑sc CO 2 ͒ has been performed in a continuous growth mode ͑analogous to chemical vapor deposition͒ where all precursors are introduced simultaneously to the reactor cell.…”