Nitrogen Plasma Ion Implantation into Carbon Films Deposited by the Anodic Vacuum ARc
- PDF / 1,535,241 Bytes
- 6 Pages / 414.72 x 648 pts Page_size
- 7 Downloads / 284 Views
IMAD F. HUSEIN, FAN LI, YUANZHONG ZHOU, RYNE C. ALLEN, AND CHUNG CHAN Plasma Science and Microelectronics Research Laboratory, Department of Electrical and Computer Engineering, Northeastern University, Boston, MA, 02115, USA
ABSTRACT Amorphous carbon films (a-C) deposited by the anodic vacuum arc on Si substrates were implanted with nitrogen using the Plasma Immersion Ion Implantation (PIIl) technique to form carbon nitride films (CN.). Scanning Electron Microscopy (SEM) of the a-C films show a surface morphology with maximum grain size in the order of a few nanometers and the exclusion of macroparticles. Increasing the nitrogen content of the CNx films increased the intensity of the X-ray Photoelecton Spectroscopy (XPS) C Is peak at 286.6 eV and formed a new peak at 285.6 eV which both can be associated with the carbon-nitrogen bond formation. Nanoindentaiton measurements showed that the hardness of the a-C films increased after implanting nitrogen into them. These CNx films exhibited a hardness of 19 GPa.
1. INTRODUCTION
The possibility of forming solids with covalent C-N bonds, such as P3-C 3N4, was proposed by Liu and Cohen in 1989 based on theoretical calculations [1]. They predicted that carbon nitrides with composition C3N4 in the J3 phase, 13-C3N 4, has a high bulk modulus comparable to diamond and its cohesive energy is moderately large. More recently, Liu et al. [2] identified a zinc-blende-like cubic and graphitelike metastable carbon nitrides with a composition of C3N4. Cohesive energy calculations showed that the 03and graphitelike structures have very close cohesive energies which suggest that in forming the 0 phase we have to overcome the competition from the energetically favorable sp2 bond found in the graphitelike phase [2]. Many experimental methods have been tried to synthesize P3-C 3N 4 using different film deposition techniques: ion beam deposition [3], RF diode sputtering [4-6], pulsed laser ablation [7], ion and vapor deposition [8], dc magnetron sputtering [3,9], and plasma decomposition of CH4 and N 2 [10]. In this study amorphous carbon films (a-C) were deposited on Si wafers by the anodic vacuum arc technique [11-13]. Carbon nitride thin films (CNn) were prepared by implanting the a-C films with nitrogen using the Plasma Immersion Ion Implantation (PilI) technique [14]. The films were characterized by X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM), and nanoindentation measurements. 281 Mat. Res. Soc. Symp. Proc. Vol. 388 ©1995 Materials Research Society
2. EXPERIMENTAL PROCEDURES The anodic vacuum arc technique was used to deposit carbon films on silicon wafers. An arc is ignited in vacuum (pressure of lx 10-5 Torr) by an electric trigger between two graphite electrodes of cylindrical geometry and sustained by a consumable anode. The anodic vacuum arc produces a partially ionized carbon vapor plasma (less than 20% ionized) [11]. Films with thickness around 0.8-1.7 i.tm (measured by a Dektak3 surface profilometer) were deposited w
Data Loading...
