摘要:

Langmuir probes combined with an energy resolved mass analyzer make satisfying contributions to the characterization of plasmas. The probes provide spatially resolved information on the well known plasma parameters, while the mass analyzer gives information on the energy distribution functions for ions/neutrals originating from some point in the plasma volume. These diagnostic tools have been used to investigate the glow discharge of the triode ion plating system of Balzers (BAI 640), a physical vapor deposition installation for the production of hard coatings. Two identical, planar Langmuir probes, positioned in the main argon plasma body, and an energy-resolved mass analyzer (Balzers PPM 421), directed to the crucible, were used to investigate the influence of the four most important process parameters, i.e., (1) the low voltage (LV) arc current, (2) the high voltage (HV) electron gun current, (3) the total pressure, and (4) the substrate voltage on the plasma parameters and on the energy spectra of ions and neutrals, during the evaporation of titanium without reactive gases. The substrate bias had no significant influence on the plasma parameters and on the energy spectra, but is very important for the microstructure of the thin film. The HV electron gun, used to melt the titanium, changed the plasma parameters only at high current values, but the energy spectra of the Ti ions changed drastically. The LV arc current and the total pressure are the process parameters that do affect both the probe characteristics and the energy spectra of ions and neutrals.

ISSN:0734-2101    

DOI:10.1116/1.581426

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

A twin-source plasma chemical vapor deposition (p-CVD) method has been designed and tested for high rate deposition ofSiO2films. In the p-CVD system, two kinds of source gases are decomposed in the plasma generators independently, and then introduced onto the substrate. The gas in front of the substrate is excited successively by a third plasma generated by coupling of rf power into the electrode just below the substrate. The films were formed at room temperature. The setup increased the collision probability of reactiveO*andSiHx*,and a high deposition rate of 1.9 μm/min was achieved by the high density of the precursors.

ISSN:0734-2101    

DOI:10.1116/1.581427

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

A new-type microwave plasma source has been developed for materials processing. The plasma reactor employed a launcher of azimuthally symmetric surface waves at a frequency of 2.45 GHz and also magnetic multicusp fields around the reactor chamber walls. This configuration yielded high-density(Ne≳1011cm−3)plasmas sustained by surface waves even at low gas pressures below 10 mTorr, following easy plasma ignition by electron cyclotron resonance (ECR) discharges. Electrical and optical diagnostics were made to obtain the plasma properties in Ar. It was shown that a transition occurs from ECR exited to surface-wave excited plasmas under conditions where the plasma electron density exceeds a critical value ofNe∼1×1011cm−3.

ISSN:0734-2101    

DOI:10.1116/1.581428

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

As parts of targets used in laser–matter interaction experiments, hydrocarbon plasma polymerized coatings of thickness between 100 nm and 30 μm with a smooth surface finish (rms⩽100 nm) are realized. For this work, a mixture of transbutene and hydrogen with the substrate in or out of the discharge is used in a low frequency (2.4 kHz) plasma reactor. The plasma is characterized by emission spectroscopy and mass spectrometry. The best results are obtained in postdischarge conditions: rms=18 nm for 2.6 μm thickness.

ISSN:0734-2101    

DOI:10.1116/1.581429

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

Molybdenum thin films were deposited onto both soda lime glass andAl2O3film by an alternate supply ofMoCl5and Zn. Zinc was used as a reducing agent. The film growth was performed over a temperature range of 400–500 °C in order to study the temperature effect on the growth. In addition to the growth temperature, the purge length after zinc was also seen to have a considerable effect on the growth. The films were analyzed by energy dispersive x-ray spectroscopy, scanning electron microscopy, elastic recoil detection analysis, x-ray diffraction and four point resistance measurements in order to determine their chemical and physical characteristics.

ISSN:0734-2101    

DOI:10.1116/1.581430

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

Titanium-based multiphase ceramic coatings were deposited by electron-beam plasma-assisted physical vapor deposition, evaporating mixtures of Ti,TiB2,and(Ti0.6Al0.4)B2.19N1.47material in Ar orAr/N2plasmas. All exhibited dense microstructures, however varying amounts of droplets or spits incorporated in the coatings produced could be observed for the different evaporation materials depending on their fabrication route. Results on the chemical composition of the coatings, obtained from glow discharge optical emission spectroscopy and Auger electron spectroscopy, showed no preferential evaporation of any element from the different evaporation source materials used, resulting in very similar compositions between evaporant and coating. Hardness values of up to 40 GPa were found for Ti–B–N based coatings containing bothTiB2andc-BNphases. Lower hardness values of around 30 GPa were observed for coatings deposited within the quaternary Ti–Al–B–N system, due to the presence ofh-BN.Two micron thick Ti–Al–B–N coatings showed only minimal wear in pin-on-disk sliding wear tests against cemented tungsten carbide balls and, with increasingh-BNcontent, a slight decrease in “stick–slip” oscillation and friction coefficient. In contrast to Ti–Al–B–N coatings (whose impact adhesion was relatively poor) Ti–B–N coatings approximately 1.5 μm thick showed no coating spallation in impact tests against cemented tungsten carbide balls and consequently superior impact wear resistance.

ISSN:0734-2101    

DOI:10.1116/1.581431

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

It is well established that the microstructure of a thin film strongly influences its physical and chemical properties. Microstructure, in turn, is determined by a number of deposition and process parameters which control the energy delivered to the growing film. The closed-field unbalanced magnetron sputtering (CFUBMS) process has now been developed to the stage where it can be routinely used to deposit very high quality, well adhered coatings of a wide range of metals and ceramics. A key factor in the success of this process is the ability to transport large ion currents to the substrate. This can enhance the formation of fully dense coating structures at relatively low homologous temperatures, compared to other sputtering systems. The importance of microstructure on the performance of a coating has led to the development of models designed to describe coating structure in terms of specific deposition parameters. Several such structure zone models (SZMs) relating to various physical vapor deposition (PVD) processes have been published. However, because of the advantages of operating in the CFUBMS mode, the structure of coatings deposited in this mode do not conform to those predicted by existing SZMs relating to other PVD processes. Also, in most existing SZMs, the final coating structure is described in terms of the homologous temperature of the coating and one other parameter which attempts to describe the additional influence on the structure of the simultaneous ion bombardment of the growing film. Several parameters have been used to fill this role including coating pressure, substrate bias voltage, and an energy parameter defined as the average energy carried by the arriving ions per condensing atom. However, other studies have shown that ion energy and ion flux are fundamental parameters in ion-assisted PVD processes and their effects must be considered separately when describing coating structures. A detailed investigation has now been carried out into the CFUBMS process. As a result of this, a SZM relating to the CFUBMS system has been developed, in which coating structures are described in terms of homologous temperature, bias voltage and the ion-to-atom ratio incident at the substrate. This is a novel model which allows the influence of ion flux and ion energy to be considered separately. This study has also highlighted a number of other characteristics of the CFUBMS system. For example, both ion current density and deposition rate are directly proportional to the target current, although their coefficients of proportionality differ. Deposition rate decreases more rapidly with increasing substrate-to-target separation than ion current. Consequently the ion-to-atom ratio incident at the substrate increases with separation. Indeed, with magnetrons of fixed magnetic configuration, in order to increase the ion-to-atom ratio for any set of deposition parameters, it is necessary to increase the substrate-to-target separation.

ISSN:0734-2101    

DOI:10.1116/1.581432

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

Thin titanium nitride films were deposited by rf reactive sputtering. The N/Ti ratio varied between 0.88 and 1.12. The optical constants have been determined by ellipsometric measurements between 1.5 and 5 eV. The normal reflectivity was measured between 0.5 and 5.5 eV. The results have been fitted by a model dielectric function based on a set of Drude–Lorentz oscillators. In this way the contributions due to free carriers and to interband transitions could be unambiguously sorted out. The analysis of the optical properties sheds light on the nature of the stoichiometry-related defects ofTiNx.It is shown that TiN contains one conduction electron per TiN unit, and that inTiNxthe square of the plasma frequency varies in a manner indicating a loss of about one electron to each nitrogen interstitial and a gain of about one conduction electron for each nitrogen vacancy. In substoichiometric material the most significant defect is the nitrogen vacancy and in nitrogen-richTiNxexcess nitrogen behaves like an interstitial defect. The occasional presence of titanium defects is also detected.

ISSN:0734-2101    

DOI:10.1116/1.581433

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

The physical, chemical, and electrical quality of the bottom electrode plays a key role in the fabrication of ferroelectric capacitors. In this article, we have used x-ray diffraction and transmission electron microscopy to study the stability of thePt/TiN/Ti/SiO2/Sistack before PZT film investigations. The Pt layer deposited by radio-frequency (rf) magnetron sputtering on such structure was strongly 〈111〉 oriented. The nucleation, growth, and orientation of lead zirconate titanate[Pb(Zr0.40Ti0.60)O3]thin film, performed by rf magnetron sputtering from ceramic target on 〈111〉 oriented platinum electrode and crystallized by rapid thermal annealing, have been investigated. The studies reveal that the PZT thin films deposited at 200 °C, with a substrate-target distance equal to 5.5 cm, using 1 Pa Ar pressure, and plasma power density of1.7 W/cm2allow good control of the film composition. The optimal annealing conditions have been then determined to achieve a pure perovskite structure (mainly 〈111〉 oriented). Ferroelectric hysteresis loop measurements indicated a remanent polarization of22.0 μC/cm2and coercive field of 50 kV/cm for the phase composition Zr/Ti=40/60.

ISSN:0734-2101    

DOI:10.1116/1.581434

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

A new device intended for UV-light generation and based on cold electron emission is proposed and analyzed theoretically. The device operation is based on the excitation by the field emitted electrons of the surrounding nitrogen(N2)molecules, which in turn emit UV light. The device should operate at low pressures compatible with field emission. The proposed device involves electrons moving in crossed electricEand magneticBfields. Equations for the electron time evolution (both radial and angular position) are obtained. When moving inside the device, the electron has a periodical cycloid-like trajectory which is always confined between two coaxial cylinders. The inner cylinder has the same radius and position with the circular array of emitters used for electron generation. The position of the outer cylinder (and so the width of the confinement zone) is controlled byEandB.The described analytical-numerical approach is used to analyze the device operation as function of model parameters.

ISSN:0734-2101    

DOI:10.1116/1.581435

出版商:American Vacuum Society    

年代:1998

数据来源: AIP