We have devised an alternative approach. This involves using suitable organic liquid-phase precursors to deposit thin (typically 100nm) films onto the substrates. The films are then subjected to thermal decomposition, which results in their being converted to a porous oxide, within which are dispersed nano-sized metal particles. We have found that a particularly suitable oxide is zirconium oxide; and a preferred metal is palladium. The palladium behaves as a highly effective catalyst. Consequently when the films are immersed in an appropriate electroless plating bath (containing an aqueous solution of the salt of the metal to be deposited) highly structured, strongly adherent metal films (for example of copper, silver, nickel or gold) are produced. These films show excellent adhesion to a range of substrates, including the combination of copper on glass. In addition, they form strong solder bonds (as measured by quantitative shear force experiments). We believe that the adhesion is provided substantially by the porous zirconia, while the highly structured nature of the deposited metal provides the basis for the improved solderability. In contrast, copper deposited by thermal evaporation is less adherent to glass, and forms much weaker solder joints.

Gold and platinum patterns have been produced by UV-induced decomposition of a range of organometallic films. A nanosecond-pulsed excimer laser operating at 193 or 248 nm was used as the source of illumination. The metal thereby formed has been extensively studied using a wide range of analytical techniques. These include scanning and transmission electron microscopy (SEM, TEM), atomic force microscopy (AFM), and energy dispersive X-ray microanalysis (EDX). This analysis has demonstrated that the metal is polycrystalline with a grain size of typically 10 nm. This technique for producing high-resolution metal patterns has wide ranging applications, especially in microelectronics.

As the trend towards device miniaturisation continues, surface effects and the thermal stability of metal deposits becomes increasingly important. We present here a study of the morphology and composition of platinum films, produced by the UV-induced decomposition of organometallic materials, under various annealing conditions. The surface composition of the metal deposits was studied by X-ray photoelectron spectroscopy, both as-deposited and following thermal treatment. In addition, the morphology of the surface was studied by atomic force microscopy which enabled the investigation of film restructuring. These studies were performed over a range of temperatures up to 1000°C in air and up to 600°C in reducing environments. Complementary information regarding the film morphology has been obtained from transmission electron microscopy. The data has been used to provide an insight into the effects of elevated temperatures on metal films deposited by a direct write method

The scanning tunneling microscope has been used to modify the surface of YBa2Cu3O7−x (YBCO) high Tc superconducting thin films by operating the instrument in the so-called mechanical milling or field-induced evaporation mode. Nanostructures such as holes, lines, and trenches were fabricated on the YBCO thin film surface in a controlled manner. In the surface modification and nanostructure fabrication processes, the effect of bias voltage, tunneling current, and scanning feedback control parameters on the modification efficiency have been investigated.

Material removal from a sample surface by operating a scanning tunneling microscope (STM) in the scanning tunneling spectroscopy (STS) mode can be controlled at the rate of a few angstroms per bias voltage ramping cycle. Monitoring the modified sample surface by tunneling spectroscopy allows determination of the electronic properties of the material. By combining these two capabilities, a novel type of depth profiling based on surface electronic properties has been proposed and studied. This depth profiling technique is based on the removal of small amounts of material obtained by operating the STM in the surface modification mode while simultaneously acquiring tunneling spectra from the material revealed by the tunneling electrons. The I–V curve profile is monitored on a pulse-by-pulse basis which allows the correlation of electronic properties with the etching depth. By this technique, the surface damage on the boron ion-implanted CVD diamond films and argon ion-etched CVD diamond films has been investigated. It has also been demonstrated that this technique can be used to measure thin film thickness. It is envisaged that this experimental technique could find applications in the characterisation of shallow-doped semiconductor devices.

Electron beam irradiation plays a vital role in the manufacture of high-resolution integrated circuits. Most of these devices are produced commercially with the use of photomasks. The photomask consists of a quartz plate, coated with a metal pattern, which in turn is projected onto the surface of the semiconductor by UV light. The manufacture of photomasks is a complex, multi-step process, in which the first stage involves the use of a sophisticated electron beam system to write the required pattern onto a polymer film. Although this can be achieved with high accuracy, the subsequent processing steps cause progressive loss of resolution.We describe here a radically new approach. This involves the use of a newly synthesised range of organometallic compounds which, under the influence of electron beam irradiation, are converted directly to metals. This thereby opens up the prospect of synthesising much-higher-resolution photomasks (including X-ray masks) in essentially a single-step process. Since the technology is capable of producing well-defined deposits of both metals and metal alloys, it also offers the promise of yielding new insights into a range of other disciplines, such as heterogeneous catalysis.

The synthesis and peirastic characterisation of two new organogold(III) complexes with a high molar ratio of gold content is described. The proposed formulae for the complexes in the present study are [C 2 H 2 Au 4 F 8 (PPh 3 ) 4 ] n and [C 2 H 2 Au 4 F 8 (NCCH 3 ) 4 ] n (Figure 1). These complexes were found to be stable to the atmosphere. The aim of this work was to demonstrate that such materials have a high metal to ligand ratio, suitable for physical vapour deposition process (PVD) and, hence, can be used as precursors for the deposition of pure metallic features. Physical and chemical characterisation methods were employed to obtain information about i) the structures, ii) the thermal and chemical stability, iii) the volatility and iv) the adhesion of these materials to specific substrates. These include n.m.r. ( 1 H, 19 F, 13 C and 31 P) IR spectroscopy, EDX (Energy Dispersive X-ray analysis), DSC ( Differential Scanning Calorimetry), TGA (Thermogravimetric Analysis), Powder X-ray Diffraction and Electron Microscopy (Scanning, Transmission and Atomic Force).

High-resolution commercial photomasks and x-ray masks are at present manufactured by a multistep process which involves the use of etching. This route imposes a limitation on the resolution that can be achieved. We describe here a new approach to the fabrication of x-ray masks involving the use of organometallic compounds which undergo direct conversion to metal under the influence of electron beam irradiation. This approach permits fabrication of both x-ray masks and extreme ultraviolet masks in essentially a single processing step. The attainable resolution is unaffected by any limitation incurred by etching processes and is dependent only on such factors as electron scattering and electron beam diameter. We describe here the production of a gold x-ray mask, which was used in conjunction with a compact laser plasma source to demonstrate the lithographic process.

The preparation a nd characterisationo f a novel organoplatinum fluoride is described. The physical vapour deposition (PVD) of the material was performed in the temperature range 160–170°C, and electron beam bombardment or uv irradiation, results in the degradation of the compound to give high quality metal features down to dimensions of ca 60 nm.

A series of novel organometallic materials has been specifically synthesised for metal track deposition under the influence of electron beam bombardment. The materials prepared are a range of organometallic fluorides containing gold or palladium and in one case, a dimer of both metals. The organometallic materials have been deposited as a layer approximately 1 μm in thickness on to a range of substrates. Reduction to the constituent metals is achieved by exposure to an electron beam, giving a final metal track thickness of around 0.1 μm. The resulting metal linewidths are determined by the diameter of the electron beam. Those described here are typically of the order of 1 μm.

Auger electron spectroscopy was carried out on a range of homogeneous SixGey (0.36 < x > 0.75, 0.25 < y > 0.64) films. Various methods of quantifying the composition of the respective films were examined, in terms of both the differential and the direct spectra. Amongst others, differentiation of the direct spectra was carried out by computational means. The removal of the background from the direct spectra by Shirley's inversion formula was investigated. In addition, any change in the composition of the films due to the variation of the inelastic mean free path formula (originated by Seah and Dench and that by Tanuma, Powell and Penn) was studied.

The products of the thermal decomposition of butane at temperatures up to 600 degrees C were identified by Raman spectroscopy. Heating to 500 degrees C resulted in tbe formation of a number of hydrocarbon products, in accordance with established reaction mechanisms. Heating to 600 degrees C, however however, led to methane as the sole product. By contrast, heating in the presence of either Al2O3 or Pt-Al2O3 yielded a different product distribution, attributed to interaction with Lewis acid sites on the Al2O3 surface. The Raman results were compared with data obtained by GC analysis.

Raman spectra have been obtained from a series of Pt/Al2O3 catalysts containing from 0 to 20% CeO2, and a Pt/CeO2 catalyst, prepared by sol-gel processing. Spectra were recorded following calcination of the catalyst Precursors at various temperatures up to 600-degrees-C and compared with thermogravimetric data. The results clearly present evidence for a strong interaction between Pt and CeO2. The surface mixed oxide species persists in an oxidising environment up to 600-degrees-C and in a reducing environment up to 170-degrees-C.

The tendency for carbonaceous deposits to accumulate on steel surfaces exposed to hydro-carbon-containing gaseous environments can be influenced strongly by the chemical nature of the elements present on their surfaces. This is known to be the case for (20% Cr, 25% Ni, ∼1% Nb) steel, which is used to contain the fuel in the core of the British Advanced Gas-Cooled reactor. It is shown here that carbonaceous deposition on to this steel can be monitored dynamically at temperature in an RF plasma discharge system containing CO2/CH4 gas and that the steel can be rendered inert to such deposition, at temperatures up to ∼ 650°C by subjecting it to prior annealing (at 800°C) in H2/H2O, thereby producing a surface which is free from iron or nickel.