F.C. Zawislak

Distributions of light ions and foil destruction after irradiation of organic polymers

It is found that light ions (6Li, 10B) distribute neither according to their calculated range nor to their nuclear damage distributions but according to their ionization distributions after implantation into organic polymers. Also, the profile of chemical destruction after low dose light ion implantation (typically 1012–1014 ions/cm2) into organic foils obeys the ionization distribution rather than the range or nuclear damage distributions. After annealing, or at higher implanted doses, a slight shift of the implantation or destruction profiles towards the nuclear damage distribution is found. The reason for this implantation behavior may be partly understood in terms of diffusion and subsequent recombination with the created radicals. Li and B distributions in carbon (which may be regarded as the final product of polymer destruction) show a shape which can be described by range profiles with subsequent diffusion and trapping at homogeneously distributed defects. In contrast to light ions, implanted heavy...

Range parameters study of medium-heavy ions implanted into light substrates

Abstract Carbon films were implanted with Cs, Xe, Sn, Rb, Kr, Ga and Cu and boron films with Bi, Pb, Au, Yb, Cs and Rb ions in an energy range of 10 to 300 keV. Range parameters were determined using the Rutherford backscattering technique. The experimental results are 20–40% higher than the theoretical predictions by Ziegler, Biersack and Littmark. Good agreement is achieved only when inelastic effects are included in the nuclear stopping regime. These features are also observed when previously published range parameter data for medium-heavy ions implanted into Be films are analyzed.

Non-regular depth profiles of light ions implanted into organic polymer films

Abstract 3 He and 10 B implantation profiles in several polymers are examined by means of a NRA technique with thermal neutrons. 200 keV 10 B ions were implanted into different kinds of polymers. In all the cases, it is found that the resulting depth profiles have a nonregular shape. A fraction which depends on the target material distributes along a tail directed towards the surface. Due to the nonregularity of the depth profiles, we present only the most probable ranges and the full width half maxima of the distributions. These results are compared with the Ziegler, Biersack and Littmark prediction. On the other hand, 3 He implanted into Mylar is found to be mobile at room temperature, as after ten days no trace of the implanted material is found in the substrate.

Range profiles of 10 to 390 keV ions (29 ≦ Z1 ≦ 83) implanted into amorphous silicon☆

Abstract Our recent range profile measurements for a series of elements (29 ≦ Z1 ≦ 83) implanted from 10 to 390 keV in amorphous silicon are compared with the Biersack-Ziegler (BZ) calculations. While the theoretical predictions are in good agreement with the experimental ranges at implantation energies larger than 70 keV, the results for several elements at lower energies are strongly underestimated by the calculations. These differences are ascribed to the Z1-range oscillation effect. In the present work we perform range calculations simulating a decrease of the elastic interaction at low energies. This approach is phenomenologically related to modifications of the charge distribution during the collisions. The results obtained show a better agreement between the calculations and the great majority of the existing low energy experimental ranges in silicon substrates.

Implanted boron depth profiles in the az111 photoresist

The isotope 10B has been implanted into the photoresist AZ111 in the 30–150 keV energy range. The corresponding depth profiles have been analyzed using the 10B(n,α)7Li reaction. At 60 keV, the profile changes from a regular shape to one with an additional tail directed towards the surface. Despite the nonregular shape of the ion distributions, it is possible to extract the characteristic range parameters such as projected range Rp, most probable range R, and full width at half‐maximum. Good agreement is found between the experimental results and the calculations by Ziegler, Biersack, and Littmark (ZBL). It is also shown that the tail distribution follows closely the ZBL calculated ionization profiles. A tentative explanation of this behavior is given.

Ranges in Si and lighter mono and multi-element targets

Abstract In the present review we describe experimental range studies for ions implanted into Si and lighter mono and multi-element targets. The experimental results are compared with current theories, in particular with the Ziegler, Biersack and Littmark (ZBL) calculations. It is found that for Si targets at implanted energies from 10 to 390 keV and for a large set of ion-Si combinations (29 ≤ Z 1 ≤ 83) there is overall a good agreement (better than 10%) between the experimental data and the ZBL calculations. However, for Au, Yb and Eu, significant theoretical-experimental differences are found when these ions are implanted at energies lower than 70 keV. The disagreement is removed when a cut-off in the interatomic potential is performed. On the other hand, systematic range studies performed in C, B, Be, SiC and polymer target films have shown that whenever medium-heavy ions are implanted in an energy range of 10 keV–7.5 MeV the experimental data are underestimated by the theory by as much as 40%. Using a simple model which takes into account the influence of the inelastic collisions on the nuclear stopping power this last difference is removed and a very good agreement is achieved between the calculated and experimental results. Finally the status for H, B and Li deep implants into Si at energies where the electronic stopping power reaches its maximum, is also reviewed.

Nucleation and growth of platelet bubble structures in He implanted silicon

He a ions were implanted into (1 0 0) Si at energies from 30 to 120 keV and fluences from 5 · 10 15 to 1 · 10 16 cm ˇ2 . After implantation, pieces of these samples were subjected to rapid thermal annealing for 600 s at temperatures ranging from 300∞C to 700∞C. The samples were analyzed by Transmission Electron Microscopy (TEM) and by Rutherford Backscattering and channeling spectrometry (RBS/C). The TEM observations were related to the RBS/C measurements and the results discussed in terms of a nucleation model to explain the formation of overpressurized bubbles in He implanted and annealed silicon. ” 1998 Published by Elsevier Science B.V.

Dose and energy dependence of implanted ion profiles (9:≦ 1 ≦ 83) in the AZ111 photoresist

The projected ranges and range stragglings of Bi, Xe, Sn, Kr, Ga, Fe, K, Ar, P, Na and F implanted into AZ111 photoresist have been measured and compared with the Biersack-Ziegler (BZ) and Gibbons et al. predictions. With the exception of the noble gases and F, the experimental results are well fitted by the BZ Monte Carlo TRIM code calculation, being independent of dose and energy. For the noble gases (Ar, Kr and Xe) we obtain ranges up to a factor of four shorter than the above predictions. The profile of fluorine changes as a function of energy. At 30 keV has a transition shape between the predicted TRIM range and ionization distributions and at 70 keV distributes according to the calculated ionization. No diffusion of implanted Bi was observed for annealings from 20 to 200°C.

Damage of ion irradiated C60 films

Abstract Thin C60 films deposited on clean silicon substrates were ion irradiated and subsequently investigated by using the Raman spectroscopy technique. The C60 films were bombarded with He, N and Bi ions at energies from 30 to 800 keV and fluences in the range 1011⩽φ⩽1016 ions cm−2. Our results reveal that both, the nuclear (Sn) and the electronic (Se) energy transfers destroy the C60 molecules. In addition it is shown that there is a well established relationship between the total energy density transfer φ(Snxa0+xa0Se) and the amount of destroyed C60 molecules. The damage process of the C60 starts when the total transferred energy density reaches the value required to release one atomic bond of C60, and the destruction is completed at a transferred energy ⩾0.5 eV A−3, which corresponds to the energy density of the C60 molecule.

Tilted angle ion implantation

Abstract Both horizontal and vertical depth profiles of implanted particles, and the spatial distribution of vacancies and ionization created by them was studied as a function of the implantation angle by means of the binary collision computer code TRIM, for a frequently examined system (100 keV boron in silicon). These predictions were checked experimentally by means of a special nuclear reaction technique with thermal neutrons. In spite of general agreement, some deviations are found for the 2nd and 4th moments.