UC Riverside

Manganese films have been identified as potential candidates for the self-formation of barriers to prevent the diffusion of copper interconnects into the underlying silicon substrate. Given the complex topography of the modern integrated circuits where these diffusion barriers are to be used and the unique nature of chemical vapor deposition (CVD) and atomic layer deposition (ALD), those methods are considered to replace the traditional physical deposition approach, forming more conformal diffusion barriers layers.

In this project, the growth of manganese-based films on silicon substrates via chemical deposition of two Mn metalorganic complexes, bis(N,N'-di-isopropyl-pentylamidinato) Mn(II)) ( Mn Amidinate) and methylcyclopentadienyl-manganese(I) tricarbonyl (MeCpMn(CO)₃, was characterized and contrasted by using an instrument equipped with a reactor coupled to a X-ray photoelectron spectroscopy (XPS) analytical chamber. The goal of this project is to develop a molecular-level understanding of the surface chemistry for the precursor to improve the selection of manganese precursors.

In our initial studies on the nature of films prepared by chemical means using MeCpMn(CO)₃ as the precursor, it was found that a manganese silicate layer grows first and a thin manganese silicide film develops latter at the SiO₂/Si (100) interface between approximately 550 and 750 K. It was also found that a typical nude ion gauge is capable of enhancing the deposition through gas-phase activation of MeCpMn(CO)₃ by electron bombardment. Finally, Mn Amidinate was proved to be highly reactive, affording the deposition of Mn at reasonable rates, higher at higher temperatures, but also leading to the incorporation of nitrogen and additional carbon in the grown Mn(0) films; MeCpMn(CO)₃, by contrast, was quite unreactive, but did not leave nitrogen contaminants on the surface. As with the carbonyl precursor, deposition with the Mn amidinate leads to the formation of a nonstoichiometric mixture of MnOx + SiOx and Mn silicate first, possibly followed by the formation of a thin subsurface Mn silicide layer. The combined Mn silicate/Mn silicide structure acts as an effective diffusion barrier, after which Mn(0) metallic films can be grown on top.

One copper precursor, copper (I)-_N,N'-di-_sec-butylacetamidinate, was also deposited on the as-formed manganese thin film above with different ratios of Mn(0) and Mn silicate. Details of the results from this work are discussed.