The 2,2,6,6-tetramethyl-2-sila-3,5-heptanedione route to the chemical vapor deposition of copper for gigascale interconnect applications

A new class of copper(II) precursors containing silylated β-diketonate ligands has been developed for the chemical vapor deposition (CVD) growth of copper for applications in ultralarge scale integration interconnect schemes, including conformal seed layer for gigascale Cu integration and ultrathin Cu lines with enhanced conductivity characteristics. Cu(tmshd)₂ (tmshdH = 2,2,6,6-tetramethyl-2-sila-3,5-heptanedione) has been studied as a representative compound and is appreciably more volatile than nonsilylated compounds such as Cu(tmhd)₂ or Cu(tmod)₂ (tmhdH = 2,2,6,6-tetramethyl-3,5-heptanedione; tmodH = 2,2,7-trimethyl- 3,5-octanedione). The CVD process employs Cu(tmshd)₂ as the metalorganic precursor and hydrogen as the reducing and carrier gas. These films were deposited using a custom made, cold wall, stainless steel CVD. Copper films were produced at a substrate temperature of 250 - 320 °C, hydrogen flow rates of 20 - 100 sccm, deposition pressure of 0.2 - 1 Torr, and a source temperature of 120 - 135 °C. The films were analyzed by X-ray photoelectron spectroscopy, cross section scanning electron microscopy, transmission electron microscopy, four-point resistivity probe, Rutherford backscattering spectrometry and Auger electron spectroscopy.