Niobium nitride films formed by rapid thermal processing (RTP): a study of depth profiles and interface reactions by...

Area of Science:

• Materials Science
• Thin Film Technology
• Surface Chemistry

Background:

• Niobium films are crucial in microelectronics.
• Understanding nitridation is key for device performance.
• Rapid thermal processing (RTP) offers controlled film modification.

Purpose of the Study:

• Compare the reactivity of ammonia and molecular nitrogen for niobium film nitridation.
• Investigate nitride and oxynitride phase formation.
• Analyze the impact of nitridation on film microstructure and elemental distribution.

Main Methods:

• Electron beam evaporation for niobium film deposition on SiO(2)/Si substrates.
• Rapid thermal processing (RTP) at 800°C using N(2) or NH(3).
• Characterization using X-ray diffraction (XRD), secondary neutral mass spectrometry (SNMS), transmission electron microscopy (TEM), energy-filtered TEM (EFTEM), and electron energy loss spectroscopy (EELS).

Main Results:

• Ammonia exhibits higher reactivity than molecular nitrogen in nitride formation and SiO(2) interaction.
• Oxynitride formation occurs near the Nb/SiO(2) interface due to oxygen out-diffusion and nitrogen in-diffusion.
• SNMS profiles show a nitrogen diffusion tail attributed to grain boundary transport.

Conclusions:

• Ammonia is a more effective nitriding agent for niobium films compared to molecular nitrogen.
• The nitridation process influences the interfacial layer composition and film microstructure.
• Grain boundaries play a significant role in nitrogen diffusion within the niobium film.