Influence Of Reactive Gas Research Articles

Phase formation and microstructure evolution of reactively r.f. magnetron sputtered Cr–Zr oxynitride thin films

Thin films in the system Cr–Zr–O–N were deposited by reactive r.f. magnetron sputtering at a substrate temperature of 500°C in various argon–oxygen–nitrogen plasmas. The depositions were realized by an experimental combinatorial approach: five substrates were placed linearly in front of a circular segmented target consisting of a metallic Cr and Zr half plate. Consequently, the coated samples exhibit different elemental compositions (with respect to their position in relation to the target half plates, i.e. from Cr-rich to Zr-rich) and constitutions. Additionally to the impact of the Cr/Zr concentration ratio (mainly determined by the sample position in relation to the target) the influence of reactive gases, i.e. oxygen and nitrogen, on phase formation, microstructure evolution, hardness and Young's modulus was investigated. For this purpose, the O2 and N2 gas flows were varied systematically, while the total gas pressure was kept constant for all depositions. The coatings were characterized by electron probe micro analysis (EPMA), X-ray diffraction (XRD) and microindentation. In dependence of the sample position and the reactive gas flow ratio coatings with various phases were grown: i) coatings with a high Cr/(Cr+Zr) concentration ratio (i.e. grown at the Cr-rich side of the target) exhibited a single-phase solid solution corundum structure with up to 1.9at.% nitrogen incorporation, (Cr,Zr)2(O,N)3. ii) coatings with similar Cr and Zr concentration (i.e. grown at the center positions of the target) exhibited a single-phase solid solution cubic ZrO2 structure with approximately 2at.% nitrogen incorporation, c-(Zr,Cr)(O,N)2. iii) coatings with a higher Zr concentration (i.e. grown at the Zr-rich side of the target) grew in mixed-phase monoclinic and tetragonal structure, incorporating up to 2.3at.% nitrogen, m+t-(Zr,Cr)(O,N)2.These coating structures developed over a wide range of oxygen and nitrogen gas flow settings and substrate positions. It indicates that oxygen determines the microstructure evolution under the chosen experimental conditions, and only little nitrogen contents can be incorporated into these oxide structures. For high nitrogen gas flows (i.e. N2/(N2+O2)>0.75) this situation changed significantly, and only coatings with face-centered-cubic CrN structures were grown. These contained up to 11.4at.% oxygen and were clearly understoichiometric in the non-metal sites. All deposited coatings exhibited hardness values between 15GPa and 27GPa, indicating their suitability as protective coatings.

Influence of reactive gas and temperature on structural properties of magnetron sputtered CrSiN coatings

CrSiN coatings were deposited on stainless steel (Grade: SA304) and silicon Si(100) substrates, with varying argon–nitrogen gas proportions and deposition temperature, using reactive magnetron sputtering technique in the present work. The influence of sputtering (Ar) and reactive gas proportions (N2) and temperature on the structural properties of the CrSiN coating was investigated. A small amount of silicon content (3.67at.% Si) plays a crucial role in addition to the nitrogen content for the formation of different phases in the CrSiN coatings as observed in the present work. For example, the coating with comparatively low nitrogen content, 40% N2, during deposition, formed a crystalline structure consisting of nano-crystalline CrN which is separated by an amorphous SiN phase, as evident from X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. The formation of CrN(111) and Cr2N(111) phases has occurred at 30% N2 with 3.67% Si content, which transformed in to CrN(111) and CrN(200) with increase in N2 content but with same Si content. The surface topography and morphology of the coatings were analyzed by atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM), respectively. A less columnar growth is observed in CrSiN coatings deposited at low argon content, Ar:N2 (20:80), and with 3.67at.% Si in the coatings. However, it becomes dense with increase in nitrogen content and temperature. The XRD analysis showed that the intensity of a dominating peak (111) is decreasing from (80:20) to (60:40) argon:nitrogen environment. With a further increase of nitrogen content, from (60:40), in the sputtering gas mixture, to (40:60) argon–nitrogen, there is a sudden increase in (111) peak and above (40:60), the peak reduction rate is very slow than the previous one. The (111) and (200) peak intensity variations are very limited due to high nitrogen content, above 50%, and considerable amount of Si atoms, 3.67at.%, present in the CrN coatings.

Optical emission characteristics of glow discharge in the N 2–H 2–Sn(CH 3) 4 and N 2–Ar–Sn(CH 3) 4 mixtures

Optical emission spectroscopy (OES) and optical actinometry were used to investigate 100 kHz low-pressure discharge in nitrogen–hydrogen–tetramethyltin and nitrogen–argon–tetramethyltin mixtures. High energy species have been identified in plasma phase. The emission intensities of main species were monitored as a function of plasma composition. The influence of reactive gases on the decomposition of tetramethyltin was investigated and plasma processes were discussed. Glow discharge plasma was characterized by optical temperatures (the electron excitation temperatures of Sn, Ar, H, vibrational temperatures of CN, N 2, N 2 + and rotational temperature of N 2 +) and by the electron number density. The obtained results revealed a strong deviation of plasma from LTE state for both analyzed mixtures. The X-ray diffraction method was applied to investigate the structure of deposited materials, being solid products of the tetramethyltin decomposition.

Influence of reactive gas on ion energy distributions in filtered cathodic vacuum arcs

The energy with which depositing species impinge on a growth surface is one of the main factors influencing the microstructure and properties of the thin films fabricated in plasma deposition processes. In this letter, we examine the effects of a variety of deposition parameters on the ion energy distribution beyond the magnetic filter in a filtered cathodic vacuum arc (FCVA). The results indicate that the ion energy distributions do not vary significantly with the magnetic field strength, magnetic field configuration, lateral position in the beam, or bias on the filter duct wall in the ranges studied. The energy distribution was however strongly affected by the presence of a reactive background gas. A reduction of 10 eV was recorded for a background pressure of 10−3 Torr of N2 gas in a carbon FCVA. This result has implications for all FCVA depositions carried out in a gas atmosphere and is consistent with the view that ion transport in the magnetic filter occurs due to an electrostatic guiding potential well.

Methods of production of short-lived isotopes at the ISOLDE (isotope separator on-line) mass separator

A survey of the target and ion-source techniques used at the ISOLDE (isotope separator on-line) facility for the production of short-lived mass-separated nuclei is given. The production of high-intensity beams of radioactive nuclei by bombardment of thick targets with 600-MeV protons or 910-MeV 3He is discussed. The release properties of various refractory target materials are presented, and the influence of reactive gases and the development of ion sources are considered. Results of on-line tests are given.

Methods for Production of Intense Beams of Unstable Nuclei: New Developments at ISOLDE

An overview of progress in the target and ion source techniques at the ISOLDE on-line mass separator is given. The production of high intensity beams of mass-separated radioactive nuclei by bombardment of targets with 600 MeV protons and 910 MeV 3He from the CERN synchro-cyclotron is discussed. Off-line tests performed in order to clarify the release properties of different target materials are described. The targets are metal powders or foils, alloys, carbides, oxides, intermetallic compounds or molten metals. The influence of reactive gases on the release rates and progress in ion-source techniques are also discussed. Recent on-line tests are described in details, and systems are suggested for the production of elements which are not yet available as primary products in on-line mass separators.

Influence of reactive gases on the conductance type of reactively sputtered NiCr layers: I Trifonov and M Czermann, Industrial Research Institute for Electronics, Budapest, Hungary pf 348

Influence of reactive gases on the conductance type of reactively sputtered NiCr layers: I Trifonov and M Czermann, Industrial Research Institute for Electronics, Budapest, Hungary pf 348

On the influence of reactive gases on sputtering and secondary ion emission

As a continuation of earlier sputtering yield measurements in an ion microprobe, the influence of oxygen and nitrogen on sputtering yield, ionisation efficiency and depth resolutions has been studied. For inert gas bombardment the yield of Ti and V falls sharply at a certain oxygen exposure. While this decrease in yield can be correlated with an increase in surface binding energy in the case of titanium, cone formation causes the yield to drop for oxygen exposed vanadium. In contrast, during nitrogen bombardment the only effect of oxygen exposure is a drastic increase of the ionisation efficiency; the sputtering yield or the depth resolution Δz/z is hardly influenced by oxygen coverage. As was observed earlier in the case of Cu−Ni layers, Δz is essentially constant for erosion depthsz≳800 A, thus yielding better resolution at large depths than is to beexpected from a sequential layer removal model. The extent of the transition zone Δz, is determined by surface topography and thus depends on the target composition as well as its structure.

1042. The influence of reactive gases on the ion bombardment-induced light emission from surfaces: G E Thomas and E E de Kluizenaar,Vide, 28 (167), 1973, 190–193

1042. The influence of reactive gases on the ion bombardment-induced light emission from surfaces: G E Thomas and E E de Kluizenaar,Vide, 28 (167), 1973, 190–193