The effect of low-energy ion bombardment on ion-beam-sputtered yttrium-oxide films was studied. Yttria films were subjected to argon ions accelerated by a potential of up to 500 V with current densities of up to 8 μA/cm2 and were deposited at differing substrate temperatures. Yttria films bombarded during deposition were found to be amorphous, and trends observed with increased ion energy include reduced amount of residual compressive stress, increased argon content, and decreased refractive index, depending on deposited energy and substrate temperature.

Thermal oxidation resistance, in a temperature range of 600 to 1100° C, of AIN-Al2O3 composite, AIN and θ-A12 O3 films has been studied. The films were prepared by microwave plasma CVD using an AlBr3 -H2 -N2 -Ar gas system at a substrate temperature of 430° C. AIN-Al2O3 composite film was found to have good surface stability below an oxidaton temperature of 1100°C and to have the best properties for insulation film.

Key words: microwave plasma CVD, AIN-Al2O3 composite, passivation film, oxidation resistance, AlBr3

Direct ion beam deposition of carbon films on silicon in the ion energy range of 15–500eV and temperature range of 25–800°C has been studied using mass selected C+ ions under ultrahigh vacuum. The films were characterized with X-ray photoelectron spectroscopy, Raman spectroscopy, and transmission electron microscopy and diffraction analysis. Films deposited at room temperature consist mainly of amorphous carbon. Deposition at a higher temperature, or post-implantation annealing leads to formation of microcrystalline graphite. A deposition temperature above 800°C favors the formation of microcrystalline graphite with a preferred orientation in the (0001) direction. No evidence of diamond formation was observed in these films.

Thin films of cubic boron nitride (c-BN) together with hexagonal one (h-BN) have been prepared by using the ion beam deposition method (IBD). Boron was deposited onto silicon wafers by a sputtering beam of 600 eV argon ions, and the growing films were simultaneously irradiated by nitrogen ions at 200 eV. The films were subsequently characterized by infrared absorption (IR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and microhardness measurements. The IR spectra show the evidence of BN layer formation by the absorption peaks at about 1350, 1120 and 810 cm−1, which are in good agreement with those of bulk BN.

Fluorinated silicon nitride films deposited from SiF4/NH3 gas mixtures by PACVD at two different frequencies have been investigated. At 13.56 MHz, low deposition rate was detected and no appreciable changes were observed when the deposition parameters varied in a wide range. On the contrary, higher deposition rates were achieved when a 35 KHz frequency was applied. These low frequency silicon nitride films showed an increase in the fluorine content In their structure when the SiF4 flow ratio in the gas mixture was increased, as detected by analytical resolution of the IR spectra. In addition, analysis of the plasma emission spectra has been performed in order to explain the effect of the plasma frequency in the deposition process.

We have studied the effect of hydrogen dilution on the structural and optical properties of plasma-deposited amorphous hydrogenated carbon. Electron spin resonance reveals that the dangling bond density does not change with hydrogen dilution, presumably because there is an excess of hydrogen present during these depositions. Information from 13C NMR, however, shows that hydrogen dilution induces changes in composition, hydrogenation, sp2/sp3 carbon bonding ratio, and the size of sp2 bonded clusters. These changes modify the electronic band structure, as observed by shifts in optical measurements.

This work investigates the modification of Fe based ion beam sputtered magnetic multilayer films in order to realize good soft-magnetic properties. Fe is used as the main magnetic material because it is the single element with the highest saturation magnetization. Then, I attempt to obtain Fe with zero magnetostriction and soft-magnetic properties artificially using a multilayering technique, while maintaining the highest possible saturation magnetization. Magnetostriction is changed by one of two following causes: by a change in the balance between positive and negative magnetostriction layers, as seen in for example Fe/Co film, or by a change in crystal orientation, as seen in for example Fe/Si02 film. Multilayer film with positive and negative magnetostriction layers is confirmed to show the same inverse magnetostrictive effect as that in uniform film. Also, the small crystal grains and the magnetostatic coupling cause a decrease in anisotropy dispersion, and lead to soft-magnetic properties, in the multilayer films. Additionally, the minimum coercivity in Fe/ SiO2 film corresponds well to the maximum in-plane uniaxial anisotropy and the minimum perpendicular anisotropy where magnetization is restricted almost completely in the plane.

A high-current, low-energy multi-ion beam deposition system has been developed for the fabrication of tailored new materials. This system consists of two ion sources, a dual-sector type mass analyzer and a deceleration system. Several ion species can be extracted successively from the two ion sources by switching the mass analyzer selection. Artificially structured materials, especially having a layered structure, can be grown by the fine control of the growth process of each layer. Ar* ion deceleration characteristics of this ion beam deposition system and preliminary results about the epitaxial growth of Ca film on Si(100) are shown.

The optical emission spectra resulting from ion beam sputtering a BaTiO3 target were observed as a function of position. A collimated optical fiber bundle parallel to the plane of the sputter target was translated vertically and horizontally to spectroscopically profile the sputter process. The Ar contours provide an image of the incident beam and its distortion by the presence of the target. Comparison of the Ar and O contours indicate that the oxygen atmosphere in the vicinity of the target is determined by sputtering events as well as the incident beam. The shapes of the Ba and Ti contours are elliptical with some differences in intensity gradients. Comparison is made with species contours observed during rf sputtering of an Y-Ba-Cu-O target.

The x-ray reflectivity and surface morphology of C/W multilayers fabricated by ion beam sputtering (IBS) method was evaluated. Also the surface roughness and amorphous structure of C and W films fabricated by direct ion beam deposition (DIBD) method were evaluated as a function of ion energy. The reflectivity was measured by the C-K line (4.47nm) and STM was used for surface roughness measurement and root-mean-square value of correlation function of the RHEED pattern was used for evaluation of amorphous structure. The reflectivity of C/W multilayer was about 69% of the theoretical one, and micro-columnar structures were observed from STM images. The film structure and surface roughness of DIBD film were changed with the depositing ion energy. The surface roughness of films becomes smaller as the depositing energy becomes higher in the energy range from 20 to 140eV.

The short time ion bombardment during ion milling resulted in a dramatic change in the surface composition of alpha-brass, selectively removing up to 2/3 of the Zn atoms during the first 5 to 10 minutes of ion milling. This differential sputtering occurred at various ion beam energies and at target temperatures as low as −196°C (LN2 temperature). The effect of differential sputtering completely disappeared after ion milling times in excess of three hours. Such a dramatic change in composition could not be attributed either to a difference in sputtering yield or to different ion milling conditions. It was shown that under constant ion milling conditions this differential sputtering depends strongly and only on the condition of the foil surface. The unexpected disappearance of the effect of differential sputtering with time was attributed to stabilization of a characteristic surface topography produced by long time ion bombardment.

We describe here a novel technique for surface modification in which a metal plasma is employed and by which various blends of plasma deposition and ion implantation can be obtained. The new technique is a variation of the plasma immersion technique described by Conrad and co-workers. When a substrate is immersed in a metal plasma, the plasma that condenses on the substrate remains there as a film, and when the substrate is then implanted, qualitatively different processes can follow, including ‘conventional’ high energy ion implantation, recoil implantation, ion beam mixing, ion beam assisted deposition, and metallic thin film and multilayer fabrication with or without species mixing. Multiple metal plasma guns can be used with different metal ion species, films can be bonded to the substrate through ion beam mixing at the interface, and multilayer structures can be tailored with graded or abrupt interfaces. We have fabricated several different kinds of modified surface layers in this way.

Selective deposition of copper in SiO2 trenches has been carried out using plasma immersion ion implantation and electroless Cu plating. To form the seed layer for electroless Cu plating on SiO2 , sputtered Pd and Si atoms were partially ionized by the Ar plasma and then deposited at bottoms of SiO2 trenches; Ar ions also assisted the ion beam mixing of the deposited Pd/Si films with the SiO2 substrate. We found a threshold Pd dose of 2–3×1014/cm2 is required to initiate the electroless plating of Cu. By controlling the Pd dose and the tapering angle of the SiO2 trench sidewalls, 1 μm wide Cu filled lines with flat surfaces suitable for planarized multilevel metallization were successfully fabricated.

Plasma etching of Al-1%Si-2%Cu presents serious challenges in corrosion, residue, and critical dimension (CD) control in single wafer etchers. One approach is to pattern the metal with oxide mask so chlorine can no longer be trapped in resist and sidewall polymers to cause corrosion. The magnetron-enhanced reactive-ion-etching (MERIE) offers a high degree of ionization at very low pressure, so anisotropic etching with reasonably high etch rate can be achieved even without sidewall protection. This paper summarizes our MERIE process characterization in terms of the effects of SiCl4 flow rate and plasma power on selectivity and CD control using an oxide mask. Typical etching was performed at 1000 watts and 40 sccm SiCl4 with the unthrottled pressure at 4.0 mTorr and a self-induced dc bias of 75 V. A 2-minute NF3 plasma at 250 watts and 100 sccm of NF3 flow served as the passivation step. This metal etch process has been successfully implemented in a doublelayer-metal interconnect technology.

Argon plasma exposure has been used to induce surface chemical modification of aluminium thin films, causing a drastic change in etch rate in standard HNO3/CH3COOH/H3PO4 etchant. The inhibition period was found to increase with power and Ar plasma exposure time. Auger electron and x-ray photoelectron spectroscopies have indicated formation of an aluminium fluoride (AlF3) surface layer due to fluorine contamination originating from the residue left in the plasma chamber during CF4 processing. The high etch selectivity between unexposed and argon plasma exposed regions has been exploited as a new technique for resistless patterning of aluminium.