Copper films given multiple sequences of Ta implantation and Cu depositions were analyzed using electron microscopy, backscattering, and Auger spectroscopy. Ta retention is 92% following direct implantation, and 100% retention was achieved for the same Ta dose if sputtered Cu is replaced during implantation. Lateral migration of Ta and microroughness were observed for all cases studied. Evidence for TaC formation is presented.

Characteristics of maskless patterning of Cr films using focused Sb+ ion implantation have been investigated. Dose and depth dependence of the etching rate of Sb-implanted layers during plasma etching using CCl4 were measured. Sb profiles were also measured by Rutherford backscattering techniques. It was found that a sharp threshold dose exists to form an etch-resistant layer by Sb implantation. It was also found that a latent image of an Sb implanted pattern at a dose ≥3.8×1015/cm2 was developed by the plasma etching, and that Cr patterns with a thickness of a few hundred nanometers were formed by the present maskless patterning technique.

Ion implantation is emerging as a versatile tool for the control of carrier lifetime in silicon. We present results on the use of argon and proton implantations to reduce lifetime. Particle energies used imply submicron penetration depths into the silicon. We find that within the first micrometer from the surface, the generation lifetime can be reduced by several orders of magnitude, and varies inversely with dose. A change in doping concentration was found only at the highest dose used (1014 cm−2). Effects of the implantations on surface generation velocity and oxide charges were also studied.

A novel low-temperature process to enhance the grain size of a polycrystalline film on an amorphous substrate has been previously reported. In this process, ion implantation is used to selectively anorphize the film, and undamaged grains act as seed crystals in a subsequent low-temperature anneal. In this work, a 120 nm polycrystalline silicon film was implanted from three angles with phosphorous at 150°K. The total dose was l.0×l015/cm2 . Transmission electron micrographs after a partial anneal (700°C for 30 minutes) indicate that some crystallites survived implantation due to ion channelling in the (111) plane. After a 60 minute anneal at 700°C, 7 μm grains were observed.

The synthesis of polymeric films under ion bombardment of frozen benzene has been investigated for the dependence of the thickness on the fluence and beam energy of keV proton and argon ions. Chemical analyses have been performed to characterize the films.

Bi single crystals have been implanted with isoelectronic ions (As, Sb and Bi) and the electronic structur of these implanted materials has been studied using the magnetoreflection technique. Since the ion penetration depth and optical skin depths are of roughly the same magnitude, this technique provides a sensitive test for implantation-induced changes in the electronic structure. Explicitly, the magnetoreflection spectra show changes in lineshape, resonant frequency and in some cases the introduction of Landau level transitions forbidden in unimplanted bismuth. In particular, implantation-induced changes in the resonance lineshapes indicate an increase in plasma frequency as either the fluence of the implants or the ion size is increased. Further analysis of the data shows that the Lax model, which accounts for the magnetoreflection spectra of unimplanted bismuth, is equally applicable to bismuth implanted with isoelectronic ions. Our results yield measurable changes in the L-point band gap and smaller relative changes in the band parameter combination Eg/m* . The mechanism responsible for these changes in the electronic structure of bismuth is suggested.

Irradiation with high energy heavy ion beams has been investigated as a technique for improving the quality of highly reflecting metallic surfaces to be used as laser mirrors. Properties such as reflectivity, corrosion resistance, film bonding, and threshold to laser surface damage have been examined. Modifications of composition and microstructure of the material associated with the heavy ion irradiation have been measured with RBS, TEM, SEM, Auger, and ESCA. Reflectivity and extinction coefficient measurements were made using ellipsometry techniques. Observations indicate that keV heavy ion irradiations in the fluence range of 1015 to 1016 cm−2 produce significant surface smoothing. Additionally, MeV implants of heavy ions into films of Cu, Ag, Au and Al deposited on molybdenum substrates resulted in improvements to both tarnish resistance and structural bonding integrity.

The adhesion of Pt films (10–330nm thick) sputter deposited on prepared substrates of yttria stabilized zirconia (YSZ) and alumina has been observed to be remarkably enhanced after irradiation with 2 MeV He++ ions and 5–30 keV electrons. The adhesion enhancement has been studied as a function ot beam energy, dose and film thickness. Thermal stability of adhesion enhancement and of the microstructure of ‘stitched’ films has been investigated. The electrochemical behaviour of ‘stitched’ Pt electrodes on YSZ has been studied by complex impedance spectroscopy.

The superconducting transition temperature, Tc, of a series of non-transition metals was improved by implantation of H and D into these metals kept below 10 K. In all cases the increase of Tc was considerably larger for H and D implantation with respect of He implantation causing only radiation effects. It could be shown that the enhancement of Tc depends on the electron-phonon coupling constant of the host metal, suggesting that mainly phonon effects dominate the improvement of Tc.

Boron ions were implanted into completed planar and edge Nb/Nb oxide/PbAuIn Josephson tunnel junctions to directly trim the Josephson pair currents, Io. The implantation caused an increase in Io and in the junction subgap conductance and a decrease in the junction energy gap. For a fixed junction fabrication procedure, the variations were observed to be monotonic with 11B implant dose. Optimum trimming was found when the 11B ions were implanted such that the peak in the depth distribution occurred at the tunnel barrier. The implantation caused an increase in Io and in the junction subgap conductance and a decrease in the junction energy gap. The implanted junctions are stable at 80°C and under storage.

A review of tribomechanical studies supported by surface analysis finds ion implantation capable of increasing the sliding wear resistance of ion implanted metals in two ways. First, it can reduce friction by modifying the surface composition (e.g. Ti+ into steel) or by promoting the growth of low friction oxide layers (e.g. N into Ti). Second, it can modify the subsurface composition and structure to resist fracture and debris formation. These modifications harden the surface, change its work-hardening behavior and/or increase residual stresses. Microindentation hardness measurements indicate that many but not all of the wear resistant surfaces are hardened by implantation; thus, surface hardness is a contributing but not necessarily a controlling factor in wear resistance. These mechanisms of wear reduction and the chemical and microstructural modifications responsible for them are discussed. Evidence for wear reduction through the migration of N during wear is critically reviewed. It is concluded that the principal benefit of ion implantation is to prevent or delay the formation of wear particles, thereby changing the wear mode during run-in and permitting metals to reach load-carrying capacities up to their elastic limits.

Implantation of nitrogen into steels is known to affect surface sensitive mechanical properties. Tensile properties of thin foils implanted with either nitrogen or helium at 300 K have been measured. Fluences greater than 1 × 1016 ions/cm2 raise the yield stress and fracture stress and reduce the plastic strain to failure. Both nitrogen and helium give comparable stress-strain responses for equal average concentrations of implanted ions. The mechanical response is discussed in terms of plastic flow of laminated structures and hardening mechanisms. Initial results of atom probe field ion microscopy examinations of nitrogen implanted Fe-15 wt.% Cr-12 wt.% Ni alloy are described.

One measure of the surface mechanical properties of materials can be obtained through microhardness data. The success of microhardness in predicting the improvements in wear resistance of ion implanted metals has been mixed. In this paper the cases of N implantation into 304 S.S. and Ti implantation into 52100 bearing steel will be examined. Microhardness data indicates little or no hardness changes whereas large wear rate changes are observed. From these two examples it is clear that the wear mechanism, the chemical nature of the surface, the ductility, and the toughness can be more important than the hardness changes.

Concentration vs. depth profiles have been calculated for Ti and C in 52100 Ti-implanted steel. A computer formalism was developed to account for diffusion and mixing processes, as well as sputtering and lattice dilation. A Gaussian distribution of Ti was assumed to be incorporated at each time interval. The effects of sputtering and lattice dilation were then included by means of an appropriate coordinate transformation. C was assumed to be gettered from the vacuum system in a one-to-one ratio with the surface Ti concentration up to a saturation point. Both Ti and C were allowed to diffuse. A series of experimental (Auger) concentration vs. depth profiles of Ti implanted steel were analyzed using the above-mentioned assumptions. A best fit procedure for these curves yielded information on the values of the sputtering yield, range and straggling, as well as the mixing processes that occur during the implantation. The observed values are in excellent agreement with the values predicted by existing theories.

Future applications of ion implantation require a knowledge of how the retention of implanted ions varies with angle of ion incidence. In this work the retention of 150-keV Ar,Ti,Cr,and Ta ions in AISI-M50 and 52100 bearing steels was measured for incidence angles up to 60° off normal. Fluences between 3×1015 and 3×1017/cm2 were used, typically on 3/8” diameter cylindrical samples. Retention was measured for Ar, Ti, and Cr by ion induced x-ray emission and for Ta by backscattering of He ions. Range and sputtering parameters needed for model calculations were experimentally determined from Ta-implanted thin Fe film samples. Generally, at the low-fluence limit a near-cos θ dependence obtained while at the high-fluence limit a (cos θ)8/3 dependence applied where θ is the angle between the sample normal and the beam direction.

The use of ion implantation for non-semiconductor applications has evolved steadily over the last decade. To date, industrial trials of this technology have been mainly directed at the wear reduction of steel and cobalt-cemented tungsten carbide tools by high dose nitrogen implantation. However, several other surface sensitive properties of metals such as fatigue, aqueous corrosion, and oxidation, have benefitted from either i)direct ion implantation of various ion species, ii)the use of ion beams to “intermix” a deposited thin film on steel or titanium alloy substrates, or iii)the deposition of material in conjunction with simultaneous ion bombardment.

This paper will concentrate on applications that have experienced the most industrial trials, mainly high dose nitrogen implantation for reducing wear, but will present the features of the other ion beam based techniques that will make them appear particularly promising for future commercial utilization.

Although the mechanical properties of nitrogen implanted cemented carbides show significant improvements in performance over unimplanted specimen, the chemical or physical mechanisms giving rise to these improvements are not well understood. Furthermore, the mechanical properties of the implanted samples under thermal stress may not be stable. This study presents analytical results obtained for a series of nitrogen implanted cemented carbides that were subsequently characterized by Auger Electron Spectrometry (AES) and Thermal Desorption Mass Spectrometry (TDMS). Results show that, in the fluence range of 0.5 to 2.5×1017 N2/cm2, peak nitrogen concentration is linear and reaches a maximum concentration of 25 a/o for the highest fluence and 180 keY energy. During vacuum heating, the implanted nitrogen is evolved rapidly between 600–700°C, which corresponds to an activation energy of approximately 7 kcal/mole (.30 ev). A small quantity of nitrogen is still present after heating to 1000°C, at an estimated average concentration of 3 a/o with little diffusional broadening as a result of post-implant heating.

Dry sliding friction tests and relative abrasive wear measurements were used to investigate the effects of ion implantation on the tribology of a centrifugally cast Co-Cr-W-C alloy. Titanium implantation was found to significantly reduce the friction and wear of the alloy. Auger spectroscopy showed that vacuum carburization of the surface occurred during Ti implantation. Similar Ti and C profiles were seen in both carbide and (Co-rich) matrix phases. The abrasive wear resistance of the alloy decreased as a result of N-implantation. Nitrogen implantation did not reduce the friction during dry sliding, however, a change in the wear mode was observed.

Commercially pure Al was implanted with 300 keV Si+ and 200 keV Pb+ to doses of between l011 and 1017 ions/cm2. Changes in friction, wear, oxidation and hardness were investigated. Silicon increased the hardness and wear resistance of Al and significantly decreased friction and the oxidation of the implanted surface. These changes were observed to be almost proportional to the implanted dose. The implantation of Pb+ resulted in a linear increase in hardness and a decrease in surface oxidation with dose. Friction decreased and wear resistance increased but the changes were not dose dependent. The implantation of Si+ did not significantly alter the distribution of impurities, such as Fe and Cu within the Al matrix, but Pb+ resulted in a diffusion of Fe to the implanted surface. Formation of precipitates was observed and the improvements in the surface properties studied are considered to result from precipitation hardening, which involves the impediment of dislocation movement by the precipitates during plastic deformation of the implanted Al.

Pin-on-disk tests were performed for comparative friction and wear behavior on flat and graded profile boron implanted beryllium samples. Peak, intended boron concentrations of 10, 20, 30 and 40 atom percent were investigated. Auger Electron Spectroscopy was used to determine the boron concentration as a function of depth. Preliminary work was performed to study the effects of (1) a low temperature (450°C, 1–1/2 hours) heat treatment of the implanted specimens and (2) a change in the pin material. All of the boron implanted beryllium samples showed significant improvement versus unimplanted beryllium and an anodized beryllium surface. Graded samples showed comparable friction coefficients but inferior wear resistance with respect to the flat profile samples.