D. Fink

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 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.

Mass and energy dependence of implanted ion profiles in the AZ111 photoresist

Profiles of Bi, Xe, Sn, Kr, Ga, Fe, K, Ar, P, Na, and F implanted into the AZ111 photoresist are compared with recent theoretical predictions. With the exception of the noble gases and F, the experimental results are well fitted by the Biersack–Haggmark [Nucl. Instrum. Methods 174, 257 (1980)] Monte Carlo calculations. For the noble gases we obtain ranges up to a factor of 2 shorter than the above predictions. Fluor changes the profile as function of energy, being nearly Gaussian at 30 keV and distributing according to the calculated ionization at 70 keV.

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.

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.

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.

Background reduction in light element depth profiling by a coincidence technique

Abstract The background for B and Li depth profiling which usually limits the detection sensitivity to about 10 −6 (corresponding to 1 ppm (atomic)) in the (n, α) spectrometry, can be reduced to values of typically 10 −10 −10 −12 by a simple coincidence circuit, in combination with proper energy discrimination, thus enabling the measurement of B and Li depth profiles in the order of some parts per trillion concentration. Limiting factors are the measuring time and the natural impurity concentration in the samples examined. The sensitivity enhancement seems possible also for He depth profiling by the He(n, p)T reaction. This opens a large field of new possible applications of this technique. The reader is encouraged to apply this technique for his problems, too.

Range measurements and thermal stability study of AZ111 photoresist implanted with Bi ions

The Rutherford backscattering technique has been used to determine the range parameters of Bi ions implanted into AZ111 photoresist film at energies from 10 to 400 keV. An overall good agreement is found between the experimental results and the theoretical predictions by Biersack, Ziegler, and Littmark. It is also observed that a variation in the implantation dose does not affect the projected range and range straggling results, despite the fact that chemical modification of the implanted polymer layer is detected. In addition, we find that a shallow implantation of the polymer film with Bi ions increases the temperature at which the photoresist starts to decompose. Finally, at 300 °C the implanted Bi atoms diffuse preferentially toward the bulk. For this temperature, two different diffusion coefficients are estimated, one for the damaged region Dd=1.2×10−5 cm2/s and another for the bulk Db=1.2×10−14 cm2/s.

Universal relations between range and damage profile parameters

Abstract A critical review of the numerous results on range profiles obtained with our Monte Carlo code TRIM (in its latest version) showed that there exist several, as yet unknown, universal relations between the moments of range and damage profiles. In combination with the well-known PRAL algorithm or other recently developed analytical formulae for the energy-range relation, one may use these relations to obtain improved range and damage profile predictions with a pocket calculator. For dominant nuclear and dominant electronic interactions mostly different relations are found. The influence of the surface on the moments is smaller than commonly assumed. As the relations derived here from theoretical results are intended essentially to help experimenters in their work, we find it appropriate to give the reader a feeling for the accuracy of experimentally obtainable range profile parameters to compare with the theoretical predictions. Therefore, the influence of various effects on the range parameters is...

Range profiles of helium in solids

Abstract 50–1500 keV range profiles of 3He are presented in about 30 solid elemental targets for a wide range of doses. Theoretical predictions are compared to experimental results in each case. The four moments of the distribution are given. The backscattering yields are also presented. In addition to our own results, some representative depth profiles from other authors are included.