Synthesis of highly tetrahedral amorphous carbon by mixed-mode HiPIMS sputtering

Abstract

Tetrahedral amorphous carbon films with an sp 3 content of 80% have been produced by high power impulse magnetron sputtering (HiPIMS) operating in a mixed sputtering/arc mode. In this mode, short-lived cathode spots form in the magnetic racetrack and produce large numbers of carbon ions. The spots move rapidly, inhibiting the formation of macroparticles. An argon pressure below 2.5 mTorr was critical for obtaining films with high sp 3 content, high stress, large Tauc gap and symmetrical Raman spectra, and all four quantities were strongly correlated.

Evolution of target condition in reactive HiPIMS as a function of duty cycle: An opportunity for refractive index grading

“…[6][7][8][9][10] HiPIMS has been a topic of interest over the past decade, as it combines the advantages of magnetron sputtering with those of an ionized depositing flux. 2,11 The presence of ions is favorable as substrate bias can be used to control the kinetic energy of the depositing flux, allowing control of the microstructure of the films and improving adhesion to the substrate. 12,13 In reactive HiPIMS, metal targets are sputtered by argon mixed with reactive gases O 2 /N 2 to deposit metal oxides/ nitrides with functional properties for optical and electronic applications.…”

Noble gas control of diamond-like content and compressive stress in carbon films by arc-mixed mode high power impulse magnetron sputtering

“…Carbon films in their amorphous state may contain various amounts of diamond-like (sp 3 ) bonds, depending on the deposition conditions [1][2][3][4]. When the sp 3 content is dominant, the material is named tetrahedral amorphous carbon (ta-C) which shows the diamond-like properties of chemical inertness, high mechanical hardness, and wide bandgap suitable for particular optical applications [5].…”

“…Carbon films in their amorphous state may contain various amounts of diamond-like (sp 3 ) bonds, depending on the deposition conditions [1][2][3][4]. When the sp 3 content is dominant, the material is named tetrahedral amorphous carbon (ta-C) which shows the diamond-like properties of chemical inertness, high mechanical hardness, and wide bandgap suitable for particular optical applications [5]. Where high resistance to wear is required, especially in applications where fracture resistance is needed, the sp 3 content may be somewhat reduced to optimize the ratio of hardness (H) to the Young's modulus (E) [6] that correlates with fracture toughness.…”

A Strategy for Alleviating Micro Arcing during HiPIMS Deposition of DLC Coatings

“…For the case of magnetron sputtering, significant ionization of sputtered atoms can be usually achieved by applying high power pulses, technique known as high power impulse magnetron sputtering (HiPIMS) [11][12][13][14]. The use of HiPIMS for the deposition of DLC coatings is a relatively new topic, with first reports in 2003 [15] and then explored, adapted and optimized in different variants [16][17][18][19]. In the case of C, the ionization degree is rather small even in HiPIMS, mainly due to the high ionization energy E i of carbon (11.26 eV).…”

“…A stable operating regime can be established in a so called "mixed mode" sputtering [28,29], where a transition to arc occurs towards the end of the pulse and provides potentially higher current intensities and ionisation degrees. This was shown to be useful for obtaining highly tetrahedral amorphous carbon films [19], and studied as a separate version of HiPIMS when dealing with carbon sputtering. Nevertheless, the tendency for arcing and relatively difficult control of the process presents potential additional issues regarding the quality of the thin films, the formation of droplets on the growing film increasing the surface roughness.…”