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Some experiments on the growth of cubic boron nitride (c-BN) show that the content of c-BN in BN films depends on the film thickness. Non-cubic phases, such as amorphous and hexagonal BN, can be identified, particularly near the substrate. To understand these phase variations, elemental depth profiles of thin BN films were measured by high resolution elastic recoil detection (ERD). BN films have been prepared by r.f. glow discharge (r.f = 13.56 MHz) from a mixture of B2H6 (10% in argon) and N2. Layers 48 nm and 90 nm thick have been deposited on crystalline silicon with integrated portions of the cubic phase of 55% and 67% respectively. ERD measurements showed that the integrated boron-to-nitrogen ratio is close to unity for the thicker film, but significant enhancements of boron are found near the interface with the silicon substrate and at the surface. These enhancements are coupled with a decrease in the hydrogen content, which is about 9% on average. The elemental fluctuations will be correlated with the occurrence of different BN phases and improvements for c-BN deposition will be suggested.

Boron nitride thin films have been deposited in a magnetic field r.f. glow discharge by the decomposition of diborane and nitrogen. The influence of ion current density, bias voltage, deposition time and gas composition are measured and can be explained in terms of the subplantation model developed by Robertson for the formation of highly tetrahedral bonded amorphous carbon. The ion bombardment of the growing film creates defects (interstitials) leading to an increase in the compressive stress which is consistent with the compressive stress model suggested by McKenzie et al. The crystallization process can be explained by rearrangement processes within the high temperature region of the ion impact induced thermal spike. The validity of the subplantation model is supported by computer simulations of the ion bombardment of a hexagonal boron nitride layer. For a description of the densification process a term nmax is defined which was tested for carbon and boron nitride layers.

c-BN films have been successfully prepared in a magnetic field enhanced r.f. glow discharge ( v r.f. = 13.56MHz). Without the magnetic field, only h-BN could be detected in the infrared (IR) spectra of the deposited films. The dependence of the c-BN content on the process parameters, such as ion energy, substrate temperature, magnetic field and gas composition, was investigated by IR spectroscopy, Auger electron spectroscopy, X-ray diffraction and ellipsometric measurements. Optical emission spectroscopy of the plasma supports the assumption that this CVD process is comparable to PVD processes. A threshold value of 1.1 for the B/N ratio in the BN deposits is assumed, above which only h-BN growth is possible.

a-C:H layers prepared at different ion energies have been characterised by several methods such as13C-NMR, EELS and ESR. With increasing ion energies from 30 eV to 170 eV, the sp2 fraction of the samples rises from 27% to about 60% and the spin density increases by more than one order of magnitude due to less incorporation of hydrogen into the film. Simulaneously, the linewidth of the ESR signal becomes narrower. This can be interpreted as an increasing cluster size from single benzene rings to 3 or 4 fused 6-fold rings. Measurements of the ion energy distribution (IED) of the positive ion flux to the substrate surface indicate a saddle-shaped peak structure typical of a resistive plasma sheath. Mass spectra of the ion flux can be correlated, to a certain degree, to the appearance potentials of electron-molecule and ion-molecule collisions.

A novel arrangement for the production of a microwave plasma by electron cyclotron resonance is described. Ion currents with current densities of up to 2.5 mA cm−2 can be homogeneously extracted from the plasma over surfaces having diameters of up to 10 cm. The microwave plasmatron can be operated by various working gases. Its application in the deposition of hydrogenated amorphous carbon (a-C:H) layer has been investigated. At a high deposition rate (200 nm min−1), a-C:H layers were deposited presenting properties which were also obtained by other workers who applied different techniques.

Amorphous hydrogenated carbon films were prepared in an inductively-coupled 13.56 MHz r.f.-glow discharge. The C2H2 pressure varied between 4 × 10−4 mbar and 8.2 × 10−3 mbar. The average ion energies were in the range of about 30–350 eV. The films were characterized by measuring the hardness, stress, density and hydrogen content. Additional investigations were made by visible ion spectroscopy-infrared spectroscopy, electron energy loss spectroscopy and electron diffraction. Magnetic resonance methods like 13C nuclear magnetic resonance and electron spin resonance have been used to determine the ratio of sp2- to sp3-hybridized C atoms and the spin density.

In the present study mass spectrometric measurements were carried out on the ion flux to the substrate during the a-C:H deposition process by ion plating and r.f. glow discharge. For this purpose a portion of ion flux striking the substrate was passed through an aperture into a differentially pumped chamber, in which the energy distribution of the ions is measured by an electrostatic analyser and the e/m value by a quadrupole mass spectrometer. The discharge conditions were measured with a Langmuir probe. Depending on the discharge conditions and the hydrocarbon gas used, typical ion groups are observed. These ion groups are generated by electron impact or ion-molecule reactions.

An inductively coupled r.f. discharge was used to prepare amorphous hydrogenated carbon (a-C:H) films in a wide pressure range, at different ion energies, and at different substrate temperatures. Because of the inductive coupling the substrate bias and the r.f. power can be varied independently. The gas pressure ranged from 3 × 10−2 to 5 × 10−4 mbar and rather high deposition rates of 30 A s−1 at 8 × 10−4 mbar have been obtained. Depending on the plasma parameters and the substrate temperature, polymer-like or hard a-C:H films were prepared. Their properties were analysed by IR and visible spectrometry, and measuring the electrical conductivity, the hydrogen content, the Knoop hardness, the adhesion to different substrates, and the internal stress. Strong correlations exist between the optical gap, the relative IR absorption coefficients for the CC vibrational mode, for the integrated CHx (x = 1,2,3) stretching modes, and the conductivity of the polymer-like films. Measurements of the temperature dependence of the conductivity indicate a superposition of activated conductivity and hopping conductivity at the Fermi level. The hard a-C:H films were prepared with average ion energies between 80 and 330 eV. The films exhibited significant enhancement of the Knoop hardness from 700 kgf mm−2 (7 GPa) to 2000 kgf mm−2 (20 GPa) and density up to 2.0 g cm−3 with increasing ion energy from 80 to 160 eV. A further increase in the ion energy up to about 300 eV does not influence the film properties. Films deposited on silicon wafers had a stress of 1–6 GPa, and the critical load in scratch tests was between 20 and 30 N, being equivalent to an adhesion of about 300 MPa. The influence of the r.f. power (for constant ion energy) on the film properties was also examined.

Amorphous hydrogenated carbon films have been prepared in an inductively coupled rf reactor. Due to the inductive coupling, the ion energy and the ion current density can be varied independently. At low pressures (8 × 10 −4 mbar ) rather high deposition rates (30 A s −1 ) have been obtained. Films were prepared in a pressure range from 1.2 × 10 −3 mbar to 5.2 × 10 −4 mbar . Mechanical properties of the a-C:H films such as internal stress, the Knoop hardness and the adhesion of different substrates have been measured. In addition, physical characterization was performed by SIMS, AES, ir and vis spectrometry. Also, film properties prepared at different H 2 /C 2 H 2 ratios were examined.

Eine endgultige Beurteilung der neuen Methode der Prostatavereisung ist auf Grund der Angaben in der Literatur und eigenen Erfahrungen noch nicht moglich. Fur Nicht-Risikopatienten halten wir die Vereisung vorlaufig wegen der langeren Abstossungsphase der Nekrosen und der unvollstandigen Adenomentfernung nicht fur indiziert. Bei Patienten mit hochstem Operationsrisiko konnte sich der neuen Methode wegen der ausserordentlich geringen Operationsbelastung ein Anwendungsfeld erschliessen.