Ion mass spectrometry investigations of the discharge during reactive high power pulsed and direct current magnetron sputtering of carbon in Ar and Ar/N2

Abstract

Ion mass spectrometry investigations of the discharge during reactive high power pulsed and direct current magnetron sputtering of carbon in Ar and Ar/N-2, 2012 Ion mass spectrometry was used to investigate discharges formed during high power impulse magnetron sputtering (HiPIMS) and direct current magnetron sputtering (DCMS) of a graphite target in Ar and Ar/N 2 ambient. Ion energy distribution functions (IEDFs) were recorded in time-averaged and time-resolved mode for Ar þ , C þ , N 2 þ , N þ , and C x N y þ ions. An increase of N 2 in the sputter gas (keeping the deposition pressure, pulse width, pulse frequency, and pulse energy constant) results for the HiPIMS discharge in a significant increase in C þ , N þ , and CN þ ion energies. Ar þ , N 2 þ , and C 2 N þ ion energies, in turn, did not considerably vary with the changes in working gas composition. The HiPIMS process showed higher ion energies and fluxes, particularly for C þ ions, compared to DCMS. The time evolution of the plasma species was analyzed for HiPIMS and revealed the sequential arrival of working gas ions, ions ejected from the target, and later during the pulse-on time molecular ions, in particular CN þ and C 2 N þ . The formation of fullerene-like structured CN x thin films for both modes of magnetron sputtering is explained by ion mass-spectrometry results and demonstrated by transmission electron microscopy as well as diffraction. V C 2012 American Institute of Physics. [http://dx

SiNx Coatings Deposited by Reactive High Power Impulse Magnetron Sputtering: Process Parameters Influencing the Nitrogen Content

“…The mass and dimension of the species determines its time of flight through the plasma as well as its probability for collision, which in turn will affect the corresponding delay time. The origin of the species affects the recorded delay time as ions originating from the target exhibit higher kinetic energies compared to species that are formed by recombination or fragmentation in the plasma 37,48 . Gas rarefaction affects the temporal evolution of intensities of the sputter gases, since the gas depletes temporally in front of the target when energetic, sputtered particles cause gas heating.…”

A comparative study of direct current magnetron sputtering and high power impulse magnetron sputtering processes for CNx thin film growth with different inert gases

“…For example, the C + IEDF shows a difference of ~5 eV for 0 % and 100 % N2 in the plasma. This does not correlate with the corresponding peak target currents of 182 A for the pure Ar discharge and 172 A for the discharge in pure N2, but may be related to an increased sputter yield [28] of C in N2 and altered target surface conditions that contribute to increased sputter yields [12]. As the N2 content in the plasma increases, C dangling bonds are likely to be terminated by N during the long pulse off times.…”

“…ions at low energies of ~2.5 eV. This is commonly observed when DCMS and HiPIMS discharges are compared [12,31,32]. The origin of high energetic ions in HiPIMS processes is a matter of discussion in literature [33].…”

“…At the same time the secondary electron emission yield decreases (cf. table 1) [12] and electron quenching by excitation of N2 reduces the probability of electron impact ionization, leading to lowered peak target currents. This is supported by Langmuir probe measurements, where comparatively high Te were extracted for reactive Ar and pure N2 HiPIMS discharges of C (cf.…”

“…Therefore, high deposition rates and particle energies may counteract the formation of a FL structure. Our earlier comparative report [12] on the direct current magnetron sputtering (DCMS) and high power impulse magnetron sputtering (HiPIMS) discharges for the synthesis of CNx in N2/Ar revealed that a more pronounced FL structure is obtained by HiPIMS processes, even though higher ion energies were measured for corresponding HiPIMS processes. The study suggested the occurrence of a pulse-assisted chemical sputter process not only at the substrate, but also at the target.…”