Copper CVD Reactions of Cu(I)(hfae)(vtms) Adsorbed on TiN

Abstract

We have studied the thermal decomposition of a Cu MOCVD precursor, hexafluoroacetylacetonate copper vinyl trim ethylsilane (Cu^I (hfac)(vtms)), on both air-oxidized and N₂ ion beam sputter-annealed single crystal (100) and polycrystalline TiN surfaces. Dosing TiN with Cu^I(hfac)(vtms) at 25°C results in chemisorption of Cu^I(hfac) and desorption of vtms. On oxidized surfaces, litle or no decomposition of CF₃ groups is detected at room temperature, while on sputter-annealed polycrystalline and single crystal surfaces, a small amount of decomposition is indicated by a CF₂ feature in the C(1s) X-ray photoelectron spectroscopy (XPS) spectrum, and a low-binding energy fluoride in the F(1s) spectrum. Between 100 and 250°C, Cu^I(hfac) decomposes to evolve gaseous products and leaves Cu, F, and C on the surface. Further heating leads to diffusion of Cu into the TiN, apparently enhanced by simultaneous diffusion of F. Decomposition of the hfac CF₃ groups at elevated temperature is independent of the nature of the TiN surface (i.e. polycrystalline vs. (100), or clean vs. oxidized). However, Cu diffusion depends strongly on the surface preparation. The onset of Cu diffusion into oxidized polycrystalline, clean polycrystalline, and clean single crystal (100) TiN occurs at 250, 320, and 430°C, respectively.