Real-time monitoring of silicon nitride composition during plasma enhanced chemical vapor deposition

• Published in: Japanese Journal of Applied Physics Vol. 34; no. 4B; pp. 2172 - 2181
• Main Authors: BAILEY, A. D, GOTTSCHO, R. A
• Format: Conference Proceeding Journal Article
• Language: English
• Published: Tokyo Japanese journal of applied physics 01.04.1995
• Subjects: Applied sciences; Chemical vapor deposition (including plasma-enhanced cvd, mocvd, etc.); Cross-disciplinary physics: materials science; rheology; Electronics; Exact sciences and technology; Lithography, masks and pattern transfer; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Microelectronic fabrication (materials and surfaces technology); Physics; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Interfacial layer; Plasma; Fourier transform spectroscopy; Inorganic compounds; Process control; Binary compounds; Amorphous state; Solid-solid interfaces; Infrared spectra; Experimental study; CVD; Microelectronic fabrication; Chemical preparation; Hydrogen additions; Silicon nitrides; Chemical composition; Thin film transistor; Total reflection; PECVD
• ISSN: 0021-4922; 1347-4065
• DOI: 10.1143/JJAP.34.2172

The study of bulk and interfacial material properties during thin film deposition or growth is important for learning how to optimize and control processing conditions. Unfortunately, there have been no techniques available that offer simultaneously non-intrusive in situ monitoring, sufficient sensitivity to permit real-time data acquisition, and chemical specificity to determine how process parameters affect composition. In this work, we demonstrate that attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy can be used to provide all these capabilities for the study of plasma enhanced chemical vapor deposition of amorphous, hydrogenated silicon nitride (a-SiN:H). We use this technique to develop a low temperature deposition process where bulk H concentrations are low enough that the material could be useful as a thin film transistor gate dielectric. At the interface between the single crystallne Si substrate and the a-SiN:H layer, we observe a thin layer where the concentration of -Si-H is enriched. The appearance of two distinct absorption bands at 2190 cm -1 and 2050 cm -1 suggests that this interfacial layer is formed by amorphisation and hydrogenation of the single crystalline Si substrate. At the interface between the deposited nitride and the reactive plasma, there is an enriched layer of -N-Si-H that appears to act as an intermediate to a-SiN:H growth.