Synthesis of Ultrathin Ta-C Films by Twist-Filtered Cathodic Arc Carbon Plasmas

Abstract

The application of cathodic-arc-deposited films has been very slow due to the infamous macroparticle problem. We report about the application of the open Twist Filter as the key component to an advanced filtered cathodic arc system. Ultrathin tetrahedral amorphous carbon (ta-C) films have been deposited on 6 inch wafers. Film properties have been investigated with respect to application in the magnetic data storage industry. Films can be deposited in a reproducible manner where film thickness control relies on arc pulse counting once deposition rates have been calibrated. Films of 3 nm thickness have been deposited that passed acid and Battelle corrosion tests. Monte Carlo Simulation of energetic carbon deposition shows the formation of an intermixed transition layer of about I inm. The simulation indicates that because the displacement energy of carbon is not smaller than of magnetic materials, films thinner than 2 nm are either not high in sp 3 content or represent a carbidic phase, i.e. contain substrate material. The last finding is general and not limited to cathodic arc deposited ta-C films.

Effect of high substrate bias and hydrogen and nitrogen incorporation on density of states and field-emission threshold in tetrahedral amorphous carbon films

“…It was observed that there was further enhancement in properties with hydrogen and nitrogen incorporation. The best properties measured with in the range of hydrogen and nitrogen incorporation in the present study were N ͑E F ͒ = 8.0ϫ 10 16 cm −3 eV −1 , E turn-on = 7.6 V / m, and J = 23.7 mA/ cm 2 , respectively. © 2010 American Vacuum Society.…”

“…The relatively low values of electronic defect density ͓N ͑E F ͒ = 8.0ϫ 10 16 cm −3 eV −1 ͔, field assisted electron emission threshold ͑E turn-on = 7.6 V / m͒, and a corresponding higher emission current density ͑J = 23.7 mA/ cm 2 ͒ during varying conditions of hydrogen and nitrogen incorporation in ta-C films grown at higher substrate bias ͑Ϫ300 V͒ clearly shows that there is a further scope to tailor ta-C as an electronic material by further studying and optimizing the process parameters and substrate bias could be a very critical parameter. The electron fieldemission data are explained by using the Fowler-Nordheim theory and are found to depend on the sp 3 / sp 2 ratio, microstructure, and density of states of these films.…”

“…The efficiency of the removal of macroparticles can also be improved using an S-bend magnetic filter, although it decreases the deposition rates due to reduced iontransport efficiency. [12][13][14][15][16][17] The pulsed mode of the plasma also allows better filtering of the macroparticle because the ions tend to be entrained in the plasma beam during the pulse but fall out of the plasma when the beam stops. [18][19][20][21][22] All these processes mentioned above are highly energetic processes, and the control of ion energy leads to the variation in the material properties.…”

Diamond like carbon coatings for tribology: production techniques, characterisation methods and applications

“…Introducing baffles along the filter and/or by constructing an "S" shaped filter can improve the filtering capabilities by a factor of 100. [37][38][39][40][41][42] Another advantage of FCVA is that, unlike IBD, the depositing plasma beam is neutral, and hence can deposit films onto insulating surfaces. The disadvantages of this method are the relative complexity, insufficient filtering ability for certain applications (e.g.…”

Doping of Nano-Sized Diamond Like Carbon Films and Their Characterization by Micro Raman Spectroscopy

“…extracted ion energy. From the source calibration data, extracted ion energy versus implemented rf power, the maximal percentage of sp 3 carbon coordination can be expected at the rf power of 450 W. This power should correspond to the extracted ion energy of ~95-100 eV/carbon ion [6,7].…”