Deposition of amorphous carbon nitride films using Ar/N2 supermagnetron sputter
Introduction
Field emission from carbon-based materials is of great technological and fundamental interest due to its possible application in display devices and in vacuum microelectronics. Amorphous carbon (a-C) film is of considerable interest due to its unique properties such as high hardness, low stress and chemical inertness. a-C films can be deposited by a variety of techniques. Commonly used techniques for growing a-C films include the plasma decomposition of hydrocarbon gas or the use of ion sources of different kinds [1], [2]. Besides plasma-enhanced chemical vapor deposition (PECVD), other techniques include laser ablation of graphite [3], filtered cathodic vacuum arc [4], hot-filament CVD [5], ion beam-assisted deposition [6], and magnetron sputter deposition [7]. Recent studies show that the unique properties of a-C films can be modified by incorporating nitrogen into the films. Because nitrogen addition can cause the reduction of the electrical resistivity and optical band gap width, nitrogen-incorporated amorphous carbon (a-C:N or a-CNx) has been proposed as a superior electronic material to amorphous carbon. In electron field emission, doping with nitrogen strongly influences the emission properties of amorphous carbon films [8]. Nitrogen is a very suitable atom as an n-type dopant because the atomic size is similar to C and the nitrogen atom is a donor in amorphous carbon film [9]. Supermagnetron plasma CVD has been used for the deposition of hydrogenated amorphous carbon nitride (a-CNx:H) films using hydrocarbon gas (i-C4H10) [10]; however, the supermagnetron sputter used in this study is suited to the deposition of a-CNx without hydrocarbon gas. By N2 or Ar/N2 magnetron sputter, a-CNx films with high N concentration (> 20 at.%) could be formed [11], [12]. Supermagnetron sputter is also a promising method for forming a-CNx films with higher N concentration than those of a-CNx:H films formed by supermagnetron plasma CVD (< 20 at.%) [13]. Supermagnetron sputter is also suited to high-performance sputtering of the target due to its nearly uniform erosion.
In this study, we deposited a-CNx films using supermagnetron sputter and investigated the physical and chemical properties of the resulting films. To examine the electron field emission characteristics, we applied the a-CNx films to a flat-face field emitter. The threshold electric field for field emission was measured as a function of gas pressure.
Section snippets
Experimental
For the deposition of a-CNx films, a supermagnetron sputter apparatus with two parallel magnetron electrodes was used (Fig. 1) [14]. Two different rf power sources with the same rf frequency (13.56 MHz) and a phase difference of 180° were supplied to two electrodes with respect to the grounded metal chamber. The lower electrode (i.e., substrate stage) was heated to 30 °C during a-CNx deposition. However, the substrate was heated by plasma heating in this experiment. Using intermittent sputter
Results and discussion
The DC self-bias voltage (VDC) of both the upper and lower electrode with respect to the ground potential was measured at upper and lower electrode rf powers (UPRF/LORF) of 200/15 W as a function of N2 and/or Ar gas pressure, as shown in Fig. 2. The VDC of the lower electrode decreased from − 57 V to − 80 V with the increase of gas pressure from 30 to 100 mTorr, almost independently of gas species. It seems that the ion-bombarding energy on the substrate increased slightly with the increase of gas
Conclusions
a-CNx films were deposited using N2 and/or Ar supermagnetron sputter at 200/15 W or 200 W/GND. The deposition rate and optical band gap increased with the increase of gas pressure (30–100 mTorr). The hardness decreased with the increase of gas pressure, and FT-IR absorption spectra showed increases of OH, NH and CH bonds with the increase of gas pressure, indicating that a-CNx films became polymer-like with the increase of gas pressure. The nitrogen concentration of a-CNx films deposited at 200/15
References (22)
- et al.
Surf. Coat. Technol.
(1996) - et al.
Diamond Relat. Mater.
(2003) - et al.
Thin Solid Films
(1999) - et al.
Thin Solid Films
(2005) - et al.
Thin Solid Films
(2008) - et al.
Thin Solid Films
(2002) - et al.
Appl. Surf. Sci.
(2005) - et al.
Thin Solid Films
(2008) - et al.
J. Appl. Phys.
(1998) - et al.
J. Vac. Sci. Technol., A
(1996)
Appl. Phys. Lett.
Cited by (3)
Deposition of amorphous carbon films using Ar and/or N <inf>2</inf> magnetron sputter with ring permanent magnet
2012, Thin Solid FilmsCitation Excerpt :Besides plasma-enhanced chemical vapor deposition, other techniques include laser ablation of graphite [4], ion beam-assisted deposition [5] and magnetron sputter deposition [6], etc. Supermagnetron plasma CVD has been used for the deposition of hydrogenated amorphous carbon films using hydrocarbon gas (i-C4H10) [7,8]; the supermagnetron sputter whose structure is similar to a supermagnetron plasma CVD apparatus, using Ar and/or N2 gases instead of hydrocarbon gas, was found to be suited to the deposition of amorphous carbon [9]. It has already been shown that a-CNx films at high N concentrations (> 20 at.
Research progress in carbon nitride in field emission cold cathode materials
2022, Cailiao Gongcheng/Journal of Materials Engineering