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High depth resolution medium energy ion scattering (MEIS) has been used to examine the influence of dynamic defect annealing on the damage formed in silicon substrates irradiated with ultralow energy ions (1 keV B+, 2.5 keV As+). Samples were implanted to doses ranging from 3×1014 to 2×1016 cm−2 at sample temperatures −150/−120, 25, and 300 °C. For all doses examined, B implantation at 25 and 300 °C produced a near-surface disordered layer 3–4 nm thick. For doses above 1×1015 cm−2, a second, deeper damaged layer was resolved at a depth greater than the peak of the projected range (Rp) of the implanted ions. For irradiations at −150 °C, MEIS and transmission electron microscope studies indicated the formation of a continuous amorphous layer, extending from the deeper damage region to the surface. However, epitaxial regrowth of this layer was not complete after a 30 s anneal at 600 °C, being arrested near Rp by clusters containing B. The dependence of B transient enhanced diffusion on the implant temperature as observed in secondary ion mass spectrometry (SIMS) measurements is discussed in terms of different dynamic annealing conditions and the subsequent availability of interstitials that result from implantation at different temperatures. MEIS studies of the damage formation and rapid thermal annealing due to the heavier As implants, carried out at 2.5 keV to a dose of 1.5×1015 cm−2 at room temperature, confirmed that all the implanted As was trapped up to this dose. Following epitaxial regrowth at 600 °C for 20 s, approximately half of the As was observed to be in substitutional sites, consistent with the reported formation of AsnV clusters (n⩽4), while the remainder had segregated to and become trapped at the oxide interface. The damage produced by the As implant also displayed a strong dependence on the substrate temperature. Irradiation with 2.5 keV ions at −120 and 25 °C resulted in amorphous Si layers. In contrast, the damaged Si remained crystalline below the near-surface damage layer, when irradiated under the same conditions at 300 °C. Notably different As distributions were observed by SIMS in these samples following high temperature (900–1100 °C) annealing. The significant influence of complex defect agglomeration during ion bombardment on the subsequent annealing behavior is discussed.

Mass analyzed low-energy ion beams delivered into a UHV growth chamber have enormous potential for novel materials studies. However, there are significant practical problems in the production of useful ion fluxes at energies down to a few electron volts. Many of these problems have been investigated during the testing of a unique new instrument. This instrument consists of a dual source, mass analyzed, low-energy, ion beam system attached to an ultrahigh-vacuum (UHV) deposition chamber which houses equipment for in situ Auger electron spectroscopy and reflection high-energy electron diffraction analysis of the deposited material. A second UHV chamber, connected to the deposition chamber by means of a vacuum lock and sample transfer device, houses equipment for in situ low-energy electron diffraction and time-of-flight scattering and recoiling spectrometry. The instrument is briefly described herein and data are presented to illustrate the effects of various parameters on the performance of the ion beam. The parameters considered are beam line pressure, field penetration, electromagnetic fringing fields, retarding lens configuration, and ion arrival energy at the target (from 5 eV to 10 keV). The effects of these parameters on the energy spread and profile of the beam, ion-beam flux on target for various species, high-energy neutral atom content and electron content of the beam, and target chamber pressure are discussed. Examples showing the utilization of the instrument for (1) synthesis of the metastable binary compound carbon nitride, (2) deposition of ultrathin Al/Si multilayers, and (3) studying the growth mechanism of Si thin films, are presented. The prospects for materials research, film deposition, surface modification, and ion/surface chemistry studies using such an instrument are assessed.

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Ultrathin high-k layers such as hafnium oxide ͑HfO 2 ͒ in combination with a subnanometer SiO 2 or Hf silicate have emerged as Si compatible gate dielectric materials. Medium energy ion scattering ͑MEIS͒ analysis has been carried out on a range of such metal oxide chemical vapor deposition grown HfO 2 / SiO 2 and HfSiO x ͑60% Hf͒ / SiO 2 gate oxide films of thickness between 1 and 2 nm on Si͑100͒, before and after decoupled plasma nitridation ͑DPN͒. The ability of MEIS in combination with energy spectrum simulation to provide quantitative layer information with subnanometer resolution is illustrated and the effect of the DPN process is shown. Excellent agreement on the deduced layer structures and atomic composition with the as grown layer parameters, as well as with those obtained from cross section electron microscopy and other studies, is demonstrated. MEIS analysis of a high-k, metal gate TiN / Al 2 O 3 / HfO 2 / SiO 2 / Si stack shows the interdiffusion, after thermal treatment, of Hf and Al from the caplayer, inserted to modify the metal gate workfunction.