Sputtered amorphous carbon films: Microstructure, density, optical and mechanical properties

Journal Article · Sun Jan 30 04:00:00 EST 2000 · International Journal of Modern Physics B

DOI:https://doi.org/10.1142/S0217979200000121· OSTI ID:20023260

Logothetidis, S

Amorphous carbon (a-C) films, single and multilayered, were deposited by rf magnetron sputtering, from graphite, on c-Si substrates. In-situ and real-time Spectroscopic Ellipsometry (SE) was used to determine the optimum deposition conditions where the formation of controllable sp{sup 3} sites can be achieved. The growth mechanisms of sputtered a-C films and their properties (optical, compositional, density and mechanical) were studied using a variety of novel characterization techniques. SE data analysis provides: (1) the sp{sup 3} and sp{sup 2} volume fractions and (2) the optical properties, that are combined well with the density, the internal stresses and the elastic properties of ultra-thin to thick a-C films. In sputtering, the applied substrate bias voltage V{sub b} (up to {minus}200V) controls the energy (30{le}E{le}230 eV) of the Ar{sup +} ions bombarding the growing film surface, affecting all film properties and responses and classifying the films in three types. The films developed with E{approx}30 eV (rich in sp{sup 2} sites)and 30{le}E{le}130 eV (rich in sp{sup 3} sites) are defined by type 1 and 2, respectively. Type 3 is defined by films developed with E>130 eV, where the formation of a new and dense carbon phase is detected, exhibiting a semi-metallic optical behavior. The experimental results show: (a) in films of type 1 and 2 the stress, density, hardness and elastic modulus are directly related with the sp{sup 3} content and described well with the so far proposed models on the formation mechanism of tetrahedral carbon, and (b) the density and the elastic properties, in type 3 films, depend not only on the sp{sup 3} content but also on the new carbon phase. a-C films deposited by sputtering exhibit unique properties that can be tailored to meet specific application requirements. For example, the combination of single a-C films of type 1 and 2 in developing multilayered films resulted to the growth of stable, thick and highly sp{sup 3} bonded films with improved elastic properties.

• Research Organization: Aristotle Univ. of Thessaloniki (GR)
• OSTI ID: 20023260
• Journal Information: International Journal of Modern Physics B, Journal Name: International Journal of Modern Physics B Journal Issue: 2-3 Vol. 14; ISSN IJPBEV; ISSN 0217-9792
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AMORPHOUS STATE
CARBON
DENSITY
MECHANICAL PROPERTIES
MICROSTRUCTURE
OPTICAL PROPERTIES
SPUTTERING