Influence of high power impulse magnetron sputtering plasma ionization on the microstructure of TiN thin films

• Published in: Journal of applied physics 2011-05, Vol.109 (10), p.104314-104314-15
• Main Authors: Ehiasarian, A. P., Vetushka, A., Gonzalvo, Y. Aranda, Sáfrán, G., Székely, L., Barna, P. B.
• Format: Article
• Language: English
• Subjects: CHARGED PARTICLES; COHERENT SCATTERING; DEPOSITION; DIFFRACTION; DISSOCIATION; ELECTRIC PROBES; ELECTRON MICROSCOPY; ELECTRON TUBES; ELECTRONIC EQUIPMENT; ELEMENTS; IONIZATION; IONS; LANGMUIR PROBE; MAGNETRONS; MASS SPECTROSCOPY; MATERIALS SCIENCE; MICROSCOPY; MICROSTRUCTURE; MICROWAVE EQUIPMENT; MICROWAVE TUBES; NITRIDES; NITROGEN; NITROGEN COMPOUNDS; NONMETALS; PHYSICAL VAPOR DEPOSITION; PLASMA DENSITY; PNICTIDES; POROSITY; PROBES; SCATTERING; SPECTROSCOPY; SPUTTERING; SURFACE COATING; THIN FILMS; TITANIUM COMPOUNDS; TITANIUM IONS; TITANIUM NITRIDES; TRANSITION ELEMENT COMPOUNDS; TRANSMISSION ELECTRON MICROSCOPY; X-RAY DIFFRACTION
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.3579443

HIPIMS (High Power Impulse Magnetron Sputtering) discharge is a new PVD technology for the deposition of high-quality thin films. The deposition flux contains a high degree of metal ionization and nitrogen dissociation. The microstructure of HIPIMS-deposited nitride films is denser compared to conventional sputter technologies. However, the mechanisms acting on the microstructure, texture and properties have not been discussed in detail so far. In this study, the growth of TiN by HIPIMS of Ti in mixed Ar and N 2 atmosphere has been investigated. Varying degrees of metal ionization and nitrogen dissociation were produced by increasing the peak discharge current ( I d ) from 5 to 30 A. The average power was maintained constant by adjusting the frequency. Mass spectrometry measurements of the deposition flux revealed a high content of ionized film-forming species, such as Ti 1+ , Ti 2+ and atomic nitrogen N 1+ . Ti 1+ ions with energies up to 50 eV were detected during the pulse with reducing energy in the pulse-off times. Langmuir probe measurements showed that the peak plasma density during the pulse was 3×10 16 m −3 . Plasma density, and ion flux ratios of N 1+ : N 2 1+ and Ti 1+ : Ti 0 increased linearly with peak current. The ratios exceeded 1 at 30 A. TiN films deposited by HIPIMS were analyzed by X-ray diffraction, and transmission electron microscopy. At high I d , N 1+ : N 2 1+ >1 and Ti 1+ : Ti 0 >1 were produced; a strong 002 texture was present and column boundaries in the films were atomically tight. As I d reduced and N 1+ : N 2 1+ and Ti 1+ : Ti 0 dropped below 1, the film texture switched to strong 111 with a dense structure. At very low I d , porosity between columns developed. The effects of the significant activation of the deposition flux observed in the HIPIMS discharge on the film texture, microstructure, morphology and properties are discussed.