The distributions of B atoms in samples previously implanted with F+ and Ne+ with doses of 1.2×1013 cm−2 and 1.5×1015 cm−2 before and after annealing were investigated by secondary ion mass spectrometry. After annealing at 900 °C, a strong dependence of B redistribution rate on F concentration was shown. The presence of F decreased B redistribution, while that of Ne (close to F in the periodic table, but inert) did not. When postimplantation annealing was carried out at 1000 °C, the B distribution did not depend on the type of the previously implanted ions. At this temperature F atoms exit the crystal. The experiment showed that the redistribution of B implanted in Si depended on the chemical activity of the impurity present in a crystal and on its concentration.

The effect of fluorine on the redistribution of boron in ion‐implanted silicon

* Ion-Stimulated Processes * Transmutation Doping of Semiconductors by Charged Particles * Doping of Semiconductors Using Radiation Defects * Formation of Buried Porous and Damaged Layers

Radiation defect engineering

Single crystal n-type silicon samples were implanted at room temperature sequentially by molecular oxygen (16O2+) and nitrogen (14N2+) in different proportions to high fluence levels ranging from 5 × 1016 to 1 × 1018 ions cm−2 to synthesize silicon oxynitride layers of various compositions. Rapid thermal annealing (RTA) of some samples was carried out at different temperatures in nitrogen ambient. Fourier transform infrared (FTIR) measurements were performed on as-implanted and on annealed samples. The FTIR studies show that the structure of ion-beam synthesized oxynitride layers are strongly dependent on total ion-fluence as well as on the ratio of implanted oxygen and nitrogen. The SixOyNz structures formed at lower fluence levels are homogeneous, at intermediate fluence levels are composed of separate phases of oxide, nitride and some complexes of O, N and Si and at higher fluence levels seem to have again homogeneous silicon oxynitride complex structures (SixOyNz) due to sputter limited profile of implanted ions. RTA studies show pronounced structural changes of the ion-beam synthesized layers on heat treatment at different temperatures. The spectra of annealed samples showed shift of the peak towards higher wave number. The ESR signal of silicon samples implanted to different fluence levels exhibited an isotropic g-value of 2.0045 corresponding to D-center with line width 8 G. The spin density was found to decrease with increase in ion-fluence.

Synthesis of silicon oxynitride layers by dual ion-implantation and their annealing behaviour

The mechanisms of defect formation in single crystalline epitaxial iron garnet thin films implanted with intermediate energy He+, B+, and Si+ ions have been investigated. X-ray diffraction and modeling of the implantation process are used to show the effectiveness of defect formation from the electronic energy losses of ion implants decelerating in the target. High temperature diffractometry demonstrates the existence of two centers of disorder in the crystal lattices of ion-implanted thin films: one due to the defect formation from the electronic energy losses and the other – from the nuclear energy losses of the implant ions.

Implantation of single crystalline iron garnet thin films with He+, B+, and Si+ ions

Silicon oxynitride (SixOyNz) buried insulating layers were synthesized by SIMNOX (separation by implanted nitrogen–oxygen) process by 14N+ and 16O+ ion implantation to high fluence levels 1 × 1017, 2.5 × 1017 and 5 × 1017 ions cm−2 sequentially in the ratio 1:1 at 150 keV into p-type (1 0 0) silicon wafers. The identification of structures and defects in the ion beam synthesized buried layers were carried out by FTIR, XRD and ESR measurements before and after RTA treatments at different temperatures in nitrogen ambient. The FTIR spectra show single broad absorption band in the wavenumber range 1250–600 cm−1 confirming the formation of silicon oxynitride. The integrated absorption band intensity is found to increase with increasing ion fluence and on annealing indicating gradual chemical transformation of the ion implanted layer into silicon oxynitride. The XRD data of the implanted samples show the formation of Si2N2O (O) phase of silicon oxynitride. On annealing the samples, SiO2 (H)/Si3N4 (H) phases are also formed in addition to Si2N2O (O) phase. The concentration of the formed phases is found to increase with increase in the ion fluence as well as the annealing temperature. The ESR studies both at room temperature and at low temperatures reveal the presence of a defect center associated with silicon dangling bonds. The increase in ion fluence gives rise to small variations in g-values and increase in the spin density. The spin density decreases in general with increasing the annealing temperature.

Synthesis of buried silicon oxynitride layers by ion implantation for silicon-on-insulator (SOI) structures

The synthesis of silicon oxynitride buried layers, using the sequential implantation of substoichiometric doses of oxygen and nitrogen ions, has been studied. By using cross-sectional transmission electron microscopy (XTEM), secondary ion mass spectroscopy (SIMS) and infrared transmission spectroscopy we have shown that there is an interrelation between the structure of synthesized layer and the oxygen to nitrogen dose ratio. It has been found that for the chosen implantation and annealing regimes the synthesized structure: consists of buried dielectric, structurally dense, layers which have thicknesses of between 0.12 and 0.185 μm. When the nitrogen to oxygen dose ratio is 3.5, the whole buried layer is amorphous and the interfaces of the buried layer are perfect.

Peculiarities of buried silicon oxynitride layer synthesis by sequential oxygen and nitrogen ion implantation in silicon

The effects of implantation of O + ions with an energy of 150 keV and dose of 1.2 × 10 17 cm −2 into (100) n-type silicon at different wafer temperatures have been investigated. After the implantation, the samples were annealed in an Ar flow furnace at 1200°C for 2 h. The composition and microstructure were determined using SIMS and XTEM methods. It is found that the spatial localization of SiO 2 inclusions in the buried layer can be narrowed by increasing the implantation temperature. However, the best spatial localization of the synthesised oxide precipitates occurs when the implantation temperature is sufficiently low that an amorphous buried layer is formed. An explanation for this phenomenon is discussed.

Spatial localization of the buried ion-beam synthesized layer of silicon dioxide inclusions in silicon

Interaction of Implanted into Silicon Fluorine with Radiation Defects

Behavior of Implanted Nitrogen in Si with the Buried Layer of SiO2 Precipitates

In this work, using Rutherford backscattering of 4He+ ions combined with channeling and cross-section transmission electron microscopy, we studied the solid phase epitaxial recrystallization (SPER) of buried layers of amorphous silicon (a-Si), obtained by Ar+, Ge+ or 29Si+ ion bombardment. The SPER process of buried a-Si layers is characterized by the different motion velocities of the external and internal amorphous-crystalline interfaces. At least two factors affect the motion of the a-c interfaces: the existence of implanted impurities and the difference in concentration of defects in the regions adjacent to the a-c interfaces. Both factors are the consequence of an asymmetry in the distribution of impurity and defects with respect to the initial position of a-c interfaces. A model of the recrystallization process, taking into consideration the influence of vacancies and interstitial defects on the motion of the a-c interfaces has been proposed.

A.A. Malinin

Papers

Peculiarities of buried silicon oxynitride layer synthesis by sequential oxygen and nitrogen ion implantation in silicon

Spatial localization of the buried ion-beam synthesized layer of silicon dioxide inclusions in silicon

Interaction of Implanted into Silicon Fluorine with Radiation Defects

Behavior of Implanted Nitrogen in Si with the Buried Layer of SiO2 Precipitates

Solid phase epitaxial regrowth of buried amorphous silicon layers obtained by ion irradiation