| AVS 60th International Symposium and Exhibition | |
| Thin Film | Thursday Sessions |
| Session TF+EM+NS+SS-ThA |
| Session: | Thin Film: Growth and Characterization II |
| Presenter: | K. Bernal Ramos, The University of Texas at Dallas |
| Authors: | K. Bernal Ramos, The University of Texas at Dallas R.K. Kanjolia, SAFC Hitech Y.J. Chabal, The University of Texas at Dallas |
| Correspondent: | Click to Email |
Tungsten nitride (WNx) films have been reported to form amorphous or amorphous-like phases that are desirable to be used as a diffusion barrier for copper metallization or other contact materials in microelectronics applications. The properties of tungsten nitride, such as high melting temperature, relatively low resistivity and chemical inertness, make it an attractive material for a variety of applications. Its deposition using Atomic Layer Deposition (ALD) is however poorly understood, hindering a wider use.
This work focuses on the ALD of WNx using a novel tungsten-based ALD precursor, dicarbonyl(methylcyclopentadienyl)nitrosyl tungsten (MeCpW(CO)2(NO)) and hydrazine as its co-reactant. We first examine the reactivity of MeCpW(CO)2(NO) with OH-terminated oxidized silicon surfaces (O3Si-OH) in order to better understand and control thin film deposition. In situ infrared (IR) absorption spectroscopy is used to uncover the film growth mechanisms. The spectra indicate that, at a substrate temperature range of 200-300 °C, there is a nucleation period of 5-6 cycles, after which tungsten nitride begins to grow through an expected ligand exchange mechanism, with appearance of N-H vibrational modes at ~3280 and ~1600 cm-1 after the hydrazine pulse. X-ray photoelectron spectroscopy (XPS) provides additional information on impurity concentration, such as carbon and oxygen, in addition to confirmation of the growth chemistry. XPS results indicate a low concentration of C impurities in the film bulk.
This study provides insight into the surface chemistry of the precursor’s initial reactions necessary to enable future process development and deposition of W-based materials for a wide range of applications.