Ion Implantation and Synthesis of Materials - Studium

Problems 177Behrisch, R., Wittmaack, K. (eds.): Sputtering by Particle Bombardment. III.Characteristics of Sputtered Particles, Technical Applications, Topics in AppliedPhysics, vol. 64. Springer, Berlin Heidelberg New York (1991)Matsunami, N., Yamamura, Y., Itikawa, Y., Itoh, N., Kazumata, Y., Miyagawa, S., Morita,K., Shimizu, R., Tawara, H.: Energy dependence of the ion-induced sputtering yieldsof monatomic solids. At. Data Nucl. Data Tables 31, 1–84 (1984)Nastasi, M., Mayer, J.W., Hirvonen, J.K.: Ion–Solid Interactions: Fundamentals andApplications, chap. 9. Cambridge University Press, Cambridge (1996)Sputtering, Y., Yamamura, Y., Itoh, N.: In: Itoh, T. (ed.) Ion Beam assisted Film Growth,chap. 4. Elsevier, Amsterdam (1989)Problems12.1 Consider the case of (1) Si ions incident on Au; and (2) Au ions incidenton Si; both cases for 100 keV incident energies at normal to the sample.Which would have the largest value(a) The dimensionless energy, ε;(b) The electronic energy-loss-rate, dE/dx| e ;(c) Nuclear energy-loss-rate, dE/dx| n ;(d) The projected range, R P(e) Sputtering yield, Y:, (assume binding energy U = 5 eV);(f) Maximum concentration of implanted species.12.2 Calculate the sputtering yield values of Ne, Ar, and Xe incident on Si at45 keV using the expressions for ZBL nuclear stopping given in Chap. 5and a binding energy of 4.6 eV:(a) Compare your values with the data given in Fig. 12.1(b) Calculate values of the dimensionless energy ε for the three cases.Are these ε values in a region where nuclear stopping rates woulddominate? (See Chap. 5.)(c) For a current of 10 µA cm −2 of Ar, now many monolayers(10 15 atoms cm −2 ) would be removed per second.12.3 (a) Calculate the sputtering yields for 45 keV Ge incident on Si(U = 4.5 eV), and compare with the data in Fig. 12.2a for 45 keV Arions incident on Si compare your values with the data given in Fig. 12.1(b) Estimate the maximum concentration of implanted Ge forpreferential sputtering factor values of 2 and 1/212.4 Assume you have a target of Si 50 Ge 50 sputtered by 50 keV Ar ions witha preferential sputtering yield of Si twice that of Ge. AssumeR P (Ar) = 50 nm(a) What is the initial sputter yield ratio Y Si /Y Ge ?(b) What is the steady state yield ratio Y Si /Y Ge ?(c) What is the surface concentration ratio of Si to Ge at steady state?(d) How thick a layer of SiGe must be removed to achieve steady state?