Sulfur- and Nitrogen- Containing Molybdenum Films with a Thermally Stable Precursor

Abstract

As devices become more and more complex with each generation, process requirements become more stringent and new materials are necessary. This also translates to the need of new precursors, in particular halide free organometallic precursors with high thermal stability. This combination prevents halide contamination/corrosion of the deposited and neighboring films, and expands the ALD window for processes. However, higher thermal stability should not compromise the reactivity of the precursors in the desired processes.We designed and successfully synthesized a new halide-free Mo precursor. It was characterized by 1H-, and 13C- NMR spectroscopy, and its molecular structure have been confirmed by x-ray crystallography. We studied its thermal stability, volatility, and chemical properties. Thermogravimetric analysis shows good volatility, with T½ of 230 oC and residual mass below 1%.Isothermal TGA at 130 °C indicates that the chemical is volatile and deliverable to the reaction chamber. Its thermal stress analysis showed that it is stable at 200 oC for more than 1 day, with ~1% residue mass. Pyrolysis experiments showed little decomposition at 475 °C.We used this precursor to attempt to deposit MoO, MoN and MoS based materials in mild conditions. ALD with NH3 afforded non uniform films with C contamination, and very low gpc. Similar results were obtained with H2O. On the other hand, films deposited with H2S were of uniform thickness with good gpc and selectivity for W over Si. The S content on the Mo-rich films was dependent on the deposition conditions and values as low as 6% could be obtained. Figure 1