Ion implantation experiments of C, N and O into stainless steel have been performed with beam-line and plasma source ion implantation methods. Acceleration voltages are varied between 27 and 50 kV, with pulsed ion current densities between 1 and 10 mA/cm2. Implanted doses range from 0.5 to 3×1018cm-2, while workpiece temperatures are maintained between 25 and 800°C. The implant concentration profiles, microstructure and surface mechanical properties of the implanted materials are reported.

In order to evaluate the damage caused by a single MeV ion impact, we prepared highly oriented pyrolytic graphite specimens, each implanted with 3.1 MeV Au, Ag, Cu and Si ions at a dose of 2.3×1011 cm-2 (2300 μm-2). We then observed specimens by using friction force microscope, and found round regions caused by single-ion impacts on the implanted surface. The frictional force between the surface and the silicon-nitride tip increased in disordered regions. The number density of the regions differed at individual ion-implanted surface, and was about 1000 μm-2 at the Au-implanted surface, 880 μm-2 at the Ag-implanted surface, 372 μm-2 at the Cu-implanted surface, and 44 μπτ2 at the Si-implanted surface. We calculated the electronic stopping power and the probability of knock-on atom generation by the nuclear collision to determine which process affected the density. We found that the difference in the number density was closely related to that of nuclear collisions.

Focused Ion Beams offer a new method of measuring the size of polymer resist features on integrated circuits. The short penetration range of an ion relative to an electron is shown to offer fundamental advantages for critical dimension (CD) metrology. By confining the polymer damage to the very near surface, ion beams can induce less dimensional change than scanning electron microscopes during the measurement process. This can result in improved CD measurement precision. The erosion rate of polymers to various ion species is also presented, and we show that erosion is non-linear with ion dose. The use of FIB for forming resist cross sections is also demonstrated. An H20 gas assisted etching process for polymers has been developed, and is shown to significantly improve the quality of resist cross sections.

The Gas Field Ion Source, GFIS, promises a 109A/(cm2 str) brightness, small beam sizes, and inert gas ion species. If this performance could be demonstrated on a commercial system, the GFIS might replace the liquid metal ion source as the standard source for FIB applications. Recent work at the Max-Planck-Institut für Kernphysik (MPI-K) in Heidelberg, Germany has shown that a GFIS with a ‘Super Tipped’ emitter can be reliably fabricated and can be run with stable helium beam current for more than 200 hours. However, this GFIS source must operate in a bakable UHV chamber, at cryogenic temperatures, and at high voltages with low vibration. A GFIS is now being integrated with high resolution ion optics and a vacuum chamber designed for studying GFIS image quality and ion induced chemistry.

The ion beam induced metal deposition processes now employed by commercial focused ion beam (FIB) tools all demonstrate less than optimal characteristics for use in circuit repair, a major application of these tools. In particular, the processes have low efficiencies, the metals produced have poor conductivity, and some form of clean up is generally required to remove excess material surrounding the repair site. The gold deposition process developed for x-ray mask repair, in contrast, exhibits efficiencies 10-50 times higher with significantly less material deposited in unwanted areas. Unfortunately, the conductivity of the gold is even poorer than that of materials now used for FIB circuit repair.

In this paper, an annealing step which improves the conductivity of FIB deposited Au is described. Results are presented demonstrating resistivities of 5-15 μΩ-cm while maintaining the high efficiency of the gold deposition process. The suitability of the process for use in FIB circuit repair is discussed.

0.1 and 30 keV Si2+ focused ion beams (FIB) were implanted in two types of GaAs, one of which is semi-insulating (s.i.) GaAs, while the other is grown by molecular beam epitaxy (MBE). Successive regrowth over the implanted surface was performed using MBE-FIB combined system, and the resistance was measured. It was found that for 100 eV Si2+ FIB implantation, the sample was nonconductive without a post annealing at 800°C. After the post annealing, however, the sample became conductive, and the resistance was the same order in magnitude as the sample fabricated using 30 keV Si + FIB irradiation. This suggests a potential of selective formation of Si δ-like doped layers in GaAs and GaAs/AlGaAs using a low-energy FIB.

An exploratory deep level transient spectroscopy (DLTS) study on the possible role of illumination during thermal annealing has been carried out on Si with extended defects generated by Ar implantation and electron cyclotron resonance (ECR) hydrogen plasma. Experiments with rapid thermal anneal (RTA) using quartz-halogen lamps show only a minor role for illumination on anneal of defects generated by Ar ion damage as well as thermal generation of defects under post-hydrogenation anneal. However, significant differences are evident relative to conventional furnace anneal and it appears likely that recombination-assisted defect reactions may be quite significant in Si processing when high intensity sources such as arc lamps are adapted in RTA systems.

The continued decrease in semiconductor device feature size has required much smaller thermal processing budgets in order to achieve the required compact doping profiles. As a result, the impurity profiles have a larger dependence on the ion implant parameters, and more attention must be given to minimizing channeling, which results in deeper implanted profiles. Thus, there is a need for a detailed understanding of the dependence of the implanted profile on the key implant parameters. Since such an understanding does not exist for phosphorus implants in silicon, a detailed study has been performed by obtaining experimental phosphorus impurity profiles for a wide range of implant energies (15 - 180 keV), doses (lx1013- 8×1015 cm–2), tilt angles (0° - 10°), and rotation angles (0° - 360°). Channeling along the <100 axial channel dominates the variations. (110) planar channeling is the next most important channeling effect, appearing at higher (5°) tilt angles, where <100 axial channeling is suppressed. (100) planar channeling is not observed at the lower energies but does manifest itself for energies of 80keV and greater. Dose dependencies play a large role beginning around lxlO14 cm-2.

Silicon-On-Insulator (SOI) and advanced device technologies require the ability to fabricate uniform thin films of silicon (< 50 nm) and silicon dioxide (< 5 nm). A technique for hyper-thinning silicon and silicon dioxide films to these dimensions is described. The method is based upon etching by a high flux beam of hyperthermal (2 to 14 eV translational energy) fluorine atoms generated using Physical Sciences’ FAST technology. The fluorine atom beam contains greater than 95% atoms and less than 0.1% ions. The low ion content of the beam allows damage-free processing of these films. At the available translational energies, the fluorine atom reaction probability with silicon is near unity. Hence, high rate etching can be achieved. Silicon films have been thinned at ambient temperature (20 C) to thicknesses less than 50 nm by this technique with etching rates up to 120 nm/min demonstrated. The hyperthinning is uniform and does not affect the surface finish. Analysis of the processed surface shows no evidence of contamination from the treatment. High rate etching of silicon dioxide films has also been shown. The reaction probability of hyperthermal fluorine atoms with SiO2 films is 0.25.

The use of high dose carbon ion implantation in Si for the production of ultrathin membranes is investigated. Carbon implantations with doses up to 1018 cm-8 and energies up to 300 keV, at room temperature and 500°C were used, followed by 10 hours annealing at 1150°C. Structural and chemical analysis has been performed (including TEM, XPS, Raman and IR spectroscopies), and the etch properties have been investigated for KOH and TMAH etchants. It is found that doses higher than 1017 cm-2 are needed to obtain efficient etch-stop layers in TMAH, independently of the annealing conditions, while in contrast with previous work, it was not possible to obtain satisfactory results using KOH. According to this, ultrathin crystalline membranes (below 500 nm thick) with average surface roughness as low as 4.8 nm, measured by AFM, were obtained, and the structural analysis revealed the formation of a highly stable buried layer of crystalline β-SiC precipitates aligned with the Si matrix. These results corroborate the ability of high dose C ion implantation to obtain buried layers usable for micomachining applications.

The diffusion of Au in Si and its binding to cavities and to precipitates of the equilibrium Au-Si phase were investigated in the temperature range 1023-1123 K using ion implantation and Rutherford backscattering spectrometry. The diffusivity-solubility product for interstitial Au was found to be about an order of magnitude greater than the extrapolation of previous, indirect determinations at higher temperatures. Chemisorption on cavity walls was shown to be more stable than Au-Si precipitation by 0.1-0.3 eV in the investigated temperature range, indicating that cavities are effective gettering centers for Au impurities.

The crucial problem for buried layer formation using MeV implantation is the reduction of anomalous leakage current at the phosphorus dose of lxl014/cm2. We have demonstrated that the origin of anomalous leakage current is dislocations, on {111}Si planes, elongated along the <110 direction and that these defects can be reduced by using a high ramping rate above 50°C /sec. At the low ramping rate below 10°C/sec, high leakage current above 1 nA was observed , which was caused by the extension of dislocations to the surface. On the other hand, by increasing the ramping rate above 50°C/sec, dislocations were formed around the Rp, but they did not extended to the surface and as a result, low leakage current was obtained. These results suggest that some kinds of defects can be suppressed by ramping rate.

A new silicon material, silicon-on-defect-layer (SODL), has been measured by secondary ion mass spectrometry (SIMS) and spreading resistivity (SR) measurements. SIMS data show that the buried defect-layer in SODL consists of silicon oxide due to the gettering of intrinsic oxygen by proton-implanted damage. Furthermore, SODL procedure makes a silicon wafer contain much fewer oxygen in surface-layer on the defect-layer, resulting in a purfied surface-layer. Measurements of SR indicate that the surface-layer of n-type silicon wafer was converted to p-type silicon after SODL procedure. A metal oxide semiconductor (MOS) device with a value of the electron mobility in the inversion mode of 714 cm2/(V s) was fabricated on SODL material. Like isolation function of a well in a complementary MOS (CMOS) device, the p-n junction in SODL material could play a role of isolation between the surface-layer and bulk. In addition, by reducing the implantation energy, SODL technology for making p-n junction, in which built-in field separates light-generated electrons and holes, is a candidate to make cheap solar cells by using low-quality low-cost silicon.

In shallow junction formation with junction depth below 0.1μm, enhanced diffusion control is essential. The purpose of this paper is to investigate the B enhanced diffusion by point defects, introduced by high dose implantation with amorphization. Ge ions were implanted to induce amorphization within the S/D region of pMOS. These results were compared with that of the B enhanced diffusion by point defects, induced by Si+ implant with non-amorphization. These results suggest that the B enhanced diffusion in lateral profiles is much smaller, compared with that in vertical profiles, when point defects were introduced by amorphization.

For low energy B (LEB) implantation into Si, the channeling tail is larger than for BF2+ implantation, so Ge+ preamorphization is expected to provide a shallower junction. We studied the Ge+ and B+ implantation damages and the damage-induced B diffusion. The substrate implanted Ge+ with 2×l014 cm-2, that is, a complete amorphization, retains less residual defects after RTA. However the sheet resistivity (S) is higher than the sample implanted with only LEB. Solid phase epitaxy (SPE) of amorphized layer causes B out-diffusion. The diffusion length of the amorphized substrate is smaller than that of LEB. We expect that the B diffusion is enhanced by the LEB damage, which corresponds to the enhanced diffusion of light damage.

The surface morphology of high dose Co implanted Si has been studied by atomic force microscopy. The Co implantation was performed using a metal vapor vacuum arc (MEVVA) ion source at an extraction voltage of 60 or 70 kV to a dose of 2×l017 or 4×l017 ions cm-2 at substrate temperatures Ts ranging from 210°C to 700°C. When Ts is less than about 600°C, the surface morphology of the implanted samples shows largely similar features of densely distributed narrow asperities. However, for the sample with Ts of 700°C, the surface morphology is significantly different and shows hillocks of much larger size. It is also found that when other parameters are fixed, for Ts less than about 600°C, the root-mean-square roughness Rrms increases exponentially with 7^, from the subnanometer scale to several nanometers. But for the sample with Ts of 700°C, there is an abrupt increase in Rrms to 35 nm. The variation of the surface morphology with other parameters is also discussed.

With increasing levels of integration, future generations of integrated circuit technology will require extremely shallow dopant profiles. Ion implantation has long been used in semiconductor material processing and will be a vitally important technique for obtaining ultra-shallow dopant profiles. However, implant channeling for low energy ion implantation must be understood and minimized. We report the results of a detailed experimental analysis of 275 ultra-shallow boron, BF2, and arsenic as-implanted profiles, and the development of an accurate and computationally efficient model for ultra-shallow implants.

The ultra-shallow dopant profiles have been modeled by using the Dual-Pearson approach, which employs a weighted sum of two Pearson functions to simulate the profiles. The computationally efficient model covers the following range of implant parameters: implant species B, BF2, As; implant energies from 1 keV to 15 keV; any dose; tilt angles from 0° to 10°; all rotation angles (0°-360°). This experimental analysis is important for the development of scaled devices with ultra-shallow junctions, and the computationally efficient model will enable process simulators to predict ultra-shallow as-implanted profiles accurately.

Studies of galvanomagnetic and electrical parameters of p- type Si : SiO2 in the temperature range 80 – 400 K have shown that X-ray irradiation at 80 K (Mo Ka,β and braking radiation hvmax. = 50 heV) leads to various transformations of the spectrum of electron- hole states in the band gap of such material, depending on the flux density of the X-rays. Two main processes are observed: the defect (vacancy and divacancy) formation and a charge exchange of native defects localized at the Si – SiO2 interface. The charge exchange process is rather collective and stimulated one because it is in response to an X-ray-induced ferroelectric phase transition in the SiO2- phase.

MeV ion induced damage and annealing behavior in Si are reported using 3 ion species such as B, P and Si. Si self implantations were done to reveal the intrinsic behavior of secondary defect formation by excluding the possibility of chemical interactions between substrate atoms and dopant atoms. Experimental results of B and P implantations were compared to those of Si. TEM observations showed that interstitial type secondary defects are exclusively formed at around Rp. DCXRD rocking curve analyses indicated that an isolated layer of (+) strain is built up at around Rp after strain relaxation by annealing. Sources for secondary defects were thought to be Si self interstitials. Atomistic mechanisms of secondary defect formation and the effect of ion species on them are discussed.

Maximum hole densities of 4×1018 cm-3 were produced in Al0.3Ga0.7As by C+Ga implantation and subsequent annealing at ∼800°C. The activation efficiency decreases with increasing AlAs mole fraction and the use of higher temperatures for the Ga co-implantation, due to a reduced vacancy concentration under these conditions. The C diffusivity is ≤2×10−13 cm2sec−1 at 950°C in implanted Al0.3Ga0.7As, demonstrating that C is a much more thermally stable acceptor than Be, Mg, or Zn.