The Materials Science of Thin Films 2011 Part 15 ppt

678 Emerging Thln-Film Materlals and Applications oxidation and sputter rates are equal and the oxide thickness is self-limiting. After the terminal oxide is established, new oxide continually sputters off. The result is removal of contaminants and uniform thickness on all base electrodes. A further materials problem aired in Section 9.5.3 concerns barrier mechan- ical stability during thermal cycling. The use of Sb in the Pb electrode (Fig. 14-22) is to harden it in order to prevent hillock formation. Finally, it must have occurred to the reader, well before this point, that high-T, Josephson junction devices should offer significant benefits relative to low- T, devices. Unfortunately very small coherence lengths and unstable surfaces coupled with fabrication and lithography difficulties has hindered progress. Nevertheless, Josephson tunneling across grain boundaries, serving as weak links, has been reported (Ref. 51). High-T, Josephson devices will probably not approach the sensitivities reached by low-T, devices because of thermal noise in measurement. 14.9. CONCLUSION This appears to be an opportune time to end the book or, more truthfully, to abandon it. Much remains to be said about other thin-film applications includ- ing displays, sensors, and assorted electronic, optical, thermal, and surface acoustic devices. The book by Chopra and Kaur (Ref. 52) is recommended for these and other applications. EXERCISES 1. A (100) Si wafer is covered with a SiO, mask film. A square window in the SiO, is opened to the bare Si surface by photolithography methods. If the sides of the square lie along [l IO] directions, sketch the shapes of the holes produced in the Si after etching in KOH-H,O if a. b. C. d. etching is isotropic. etching is anisotropic (Note: Anisotropic etchants create faceted holes composed of crystal planes that are etched slowest.) the initial square mask window is widened and the etching time is reduced. What shapes are produced if the initial window has a rectangular shape? Exercises 679 2. The KOH-H,O anisotropic etchant attacks lightly doped Si much more rapidly than heavily doped Si. Design a processing schedule involving doping to produce large area membranes of arbitrary thickness in Si wafers. One application is X-ray masks (see p. 410). 3. Three thin-film computer-memory schemes (magnetic film, magnetic bubble and superconducting) have been considered in this book. Com- ment on the materials properties issues and technical difficulties that have presently rendered these schemes "all but a memory." 4. Estimate the maximum thickness of a CVD diamond film that can grow epitaxially on bulk diamond without generating misfit dislocations. 5. Consider the web coating of a polymer film of thickness, d,, by a magnetic alloy of thickness, d,, in the manufacture of magnetic tape. The alloy film is sputtered and the thermal power flux density delivered to the substrate is P. This heat is removed by the chill roll and the resulting temperature history of the web is given by (see Eq. 3-34) p = web density c = web heat capacity T,= chill roll temperature h = heat transfer coefficient between web and chill roll a. Derive an expression for the web temperature if it moves at velocity v and a length L is exposed to the depositing atoms at any given instant. b. At what velocity must the web travel if d, = 10oO A, d, = 0.05 mm, = 20 "C, and L = 40 cm. Assume the maximum permissible web temperature is 100 'C, p = 1.4 g/cm3, c = 0.2 cal/g-"C, and that h = 9 x cal/cm'-sec-"C. The energy per depositing atom is 20 eV 6. a. Estimate the substrate temperature that would be required for MBE b. Diamond has an extraordinarily high surface energy. What are the growth of diamond films. prospects for heteroepitaxial growth of diamond films? 7. Consider a film medium used for magnetic recording that is perpendicu- larly magnetized with parallel stripe domains separated by 180" bound- aries. Both magnetostatic (E,,,,) as well as domain wall energy (E,) contribute to the total energy (ET). If the film thickness if d, the distance 680 Emerglng Thin-Film Materials and Applications between walls is d,, and EM = 1.07 x 1OSM~d, (in mks units). a. Show that d E~ = E,- + 1.07 x 105~:d,. dw b. What is the equilibrium value of d,? c. If M, = 0.05 T and E, = 1.7 x lop3 J/m2, what is d, if d = 2000 A? 8. By directly counting all Y, Ba, Cu, and 0 atoms in the unit cell depicted in Fig. 14-6, demonstrate that the crystal stoichiometry corresponds to the formula YBa,Cu,07 . 9. Assume that a quantum well infrared detector device based on a semicon- ductor with Eg = 0.9 eV can be simply modeled by an infinite well potential. The effective masses of conduction-band electrons and valence-band holes are 0.06mo and 0.42m0, respectively. a. In order to tune operation to 1.0-eV radiation, what well width is b. For a 1 .O-eV transition solely between conduction-band electron levels 10. The probability P that electrons launched with kinetic energy E toward a rectangular barrier (of potential energy V and thickness d) will penetrate it by quantum mechanical tunneling is given by required? how thin must the well be? 1 V2 87r2m, P(E) = 1+ si*’( 7 (V - S)‘:’dJ 4E( V - E) 0 a. Suppose V = 0.1 eV, E = 0.05 eV, and d = 40 A. Evaluate P. b. For a 10% change in d by what factor does P change? c. Is the tunneling probability enhanced more by decreasing V or increas- ing E by the same amount of energy. 11. predict values of A E, and AE, for the following rectangular quantum well structures: a* A10.3Ga0.7As/GaAs/A10.3Ga0.7As b. Alo~,,Ino~,2As/Gao~,,Ino~,2As/Alo~,,Ino~s2As lattice matched to InP. References 681 12. In the A10,,,Gao,,,As/GaAs/Alo,35Gao~65As rectangular quantum well, AEc = 0.33 eV, AE” = 0.18 eV, m:(w) = 0.067m0, mz(w) = 0.340m0, mz( b) = 0.095m0 and mX( b) = 0.36m0. If the well width is 150A, a. determine the first two electron and hole levels. b. indicate four different electron-hole transitions that could be measured with a spectrometer. c. What are the energies (in eV) of these transitions? REFERENCES 1. 2.* 3. 4.* 5. 6. 7. 8. 9. 10 11. 12.* 13.* 14. D. W. Hess, in Microelectronic Materials and Processes, ed. R. A. Levy, Kluwer Academic, Dordrecht (1989). S. Wolf and R. N. Tauber, Silicon Processing for the VLSI Era, Lattice Press, Sunset Beach, Calif. (1986). G. N. Taylor in Microelectronic Materials and Processes, ed. R. A. Levy, Kluwer Academic, Dordrecht (1989). I. Brodie and J. A Muray, The Physics of Microfabrication, Plenum Press, New York (1982). J. B. Angell, S. C. Terry, and P. W. Barth, Scientific American 248, 44 (1983). M. Mehregany, K. J. Gabriel, and W. S. N. Trimmer, ZEEE Trans. Elec. Dev. 35, 719 (1988). K. Skidmore, Semiconductor Zni. 11(9) 15 (1988). W. W. Tai, Silicon Micromachining, M. S. Thesis, Stevens Institute of Technology, Hoboken, NJ (1989). W. von Bolton, 2. Electrochem 17, 971 (1911). P. D. Bridgeman, Scientific American 233, 102 (1975). B. V. Derjaguin and D. V. Fedeseev, Scientific American 233, 102 (1975). R. C. DeVries, Ann. Rev. Mater. Sci. 17, 161 (1987). H C. Tsai and D. B. Bogy, J. Vac. Sci. Tech. A5, 3287 (1987). D. Dimos and D. R. Clarke, Surfaces and Interfaces of Ceramic Materials, eds. L. C. Dufour, C. Monty, and G. P. Ervas, Kluwer Academic, Dordrecht ( 1989). *Recommended texts or reviews. 682 Emerging Thin-Film Materials and Appllcatlons 15. J. M. Tarascon and B. G. Bagley, MRS Bull. XIV(l), 53 (1989). 16. R. Simon, Solid State Tech. 32(9), 141 (1989). 17.* J. K. Howard, J. Vac. Sci. Tech. 4A, 1 (1986). 18. T. C. Arnoldussen and E. M. Rossi, Ann. Rev. Mater. Sci. 15, 379 (1985). 19. H. N. Bertram, Proc. IEEE 74, 1494 (1986). 20.* T. C. Arnoldussen, Proc. IEEE 74, 1526 (1986). 21 ,* J. Isailovic, Videodisc and Optical Memory Systems, Prentice-Hall, Englewood Cliffs, NJ (1985). 22.* A. E. Bell in Handbook of Laser Science and Technology, Vol. V, ed. M. J. Weber, CRC Press, Boca Raton (1987). 23. M. Hartmann, B. A. J. Jacobs, and J. J. M. Breat, Philips Tech. Rev. 42, 37 (1985). 24. M. H. Kryder, J. Appl. Phys. 57, 3913 (1985). 25. J. S. Gau, Mat. Sci. Eng. B3, 371 (1989). 26. W. H. Meiklejohn, Proc. IEEE 74, 1570 (1986). 27. D. J. Gravesteijn, C. J. van der Poel, P. M. L. 0. Scholte, and C. M. J. van Uijen, Philips Tech. Rev., 44, 250 (1989). 28.* R. G. Hunsperger, Integrated Optics: Theory and Technology, Springer-Verlag , Berlin (1 984). 29. E. M. Conwell and R. D. Burnham, Ann. Rev. Mater. Sci. 8, 135 (1978). 30.* R. C. Alferness, IEEE J. Quantum Electro. QE 17, 946 (1981). 31. 32. 33. 34. 35. 36. 37. 38. 39. S. E. Miller, Bell Syst. Tech. J. 48, 2059 (1969). C. Chartier, in Integrated Optics, Physics and Applications, eds. S. Martellucci and A. N. Chester, Plenum Press, New York (1983). T. Suhara and H. Nishihara, IEEE J. Quantum Dev. QE-22, 845 (1986). L. Esaki and R. Tsu, IBM J. Res. Dev. 14, 61 (1970). L. Esaki, in Symposium on Recent Topics in Semiconductor Physics, eds. H. Kamimura and Y. Toyozawa, World Scientific (1982). R. E. Eppenga and M. F. H. Schuurmans, Philips Tech. Rev. 44, 137 (1988). R. Dingle, W. Wiegmann, and C. Henry, Phys. Rev. Lett. 33, 827 ( 1974). R. F. Kopf, Ph. D. Thesis, Stevens Institute of Technology, Hoboken, New Jersey (1991). I. K. Schuller, in Physics, Fabrication and Applications of Multilay- ered Structures, eds. P. Ghez and C. Weisbuch, Plenum Press, New York (1988). References 683 40.* F. Capasso, Science 235, 172 (1987). 41. F. Capasso and S. Dam, Physics Today 43(2), 74 (1990). 42.* R. E. Howard, W. J. Skocpol, and L. D. Jackel, Ann. Rev. Mater. Sci. 16, 441 (1986). 43. H. I. Smith and H. G. Craighead, Physics Today 43(2), 24 (1990). 44. J. Clarke, Nature 333(5), 29 (1988). 45. A. M. Wolsky, R. F. Giese, and E. J. Daniels, Scientific American 260, 61 (1989). 46. A. H. Silver, IEEE Trans. Magnetics 15(1), 268 (1979). 47. J. Clarke and R. H. Koch, Science 242, 217 (1988). 48. 0. Dossel, M. H. Kuhn, and H. Weiss, Philips Tech. Rev. 44, 259 (1989). 49. J. Matisoo, Scientific American 242(5), 50 (1980). 50. W. Anacker, IEEE Spectrum 16(5), 26 (1979). 51. R. B. Laibowitz, R. H. Koch, A. Gupta, G. Koren, W. J. Gallagher, V. Foglietti, E. Oh, and J. M. Viggiano, Appl. Phys. Lett. 56, 686 (1990). K. L. Chopra and I. Kaur, Thin Film Device Applications, Plenum Press, New York (1983). 52. Appendix 7 fi Physical Constants CONSTANT Angstrom Avogadro constant Boltzmann constant Gas constant Electronic charge Electron mass Permittivity in vacuum Planck constant Speed of light SYMBOL A NA k VALUE ZA = 10-8 cm = IO-' nm 6.022 x particles/mole = 8.617 x eV/"K 1.38 x 10-23 J/OK 1.987 cal/mole OK I .602 x IO- I9 coulomb 8.85 x F/cm 6.626 x Joule-sec 2.998 x 10" cm/sec 9.11 x 10-28g 685 Appendix 2 =E=% Selected Conversions 1 Atm = 1.013 x lo6 dynes/cm2 = 1.013 x lo5 Pa = 1.013 x lo5 N/m2 1 Torr = 1 mm Hg = 133.3 Pa 1 Bar = 0.987 Atm = 750 Torr 10’’ dynes/cm2 = lo9 N/m2 = lo9 Pa = 146000 psi 1 erg = 1 dyne-cm = lop7 Joule 1 eV = 1.602 x 1 eV/atom = 23060 callmole 1 Weber/m2 = lo4 Gauss = 1 Tesla 1 Poise (P) = 1 dyne sec/cm2 erg = 1.602 x lopi9 Joule 68 7 [...]... expansion, table, 552 Thermal history, sputtering, 115 Thermal shock, diamond, 636 Thermal shock parameter, 553 Thermal spike, 611 Thermal stress, 419, 427, 553 Thermodynamics, 21 chemical, 23 CVD, 155 nucleation, 198 Si-CI-H system, 159 -160 Thick film resistors, 463 Thin film, resistors, 463 Thin film model, 239 perfect structure, 240 stacking fault, 240 Thin film optics, 524 Thomson model, 458 Throughput,... amorphous films, 238 Au-CO, 237 cross section, 273 dark field, 271 film cross section, 229 nucleation, 196, 219 Tensile properties, metal films, 407 Tensile strength, 409 Tensile stress, 405 Tetrahedral bond, 6, 9 Thermal barrier coating, 584 Thermal coatings, 547, 584 Thermal conductivity, diamond, 636 table, 552 Thermal cycling, 437 Thermal diffusion, 596 Thermal expansion, table, 552 Thermal history,... 83 heat of, 99 Sublimation furnace, 98 Substrate, temperature-time, 117 thermal history, 115- 116 Substrate temperature, nucleation, 203 Sulfidation, 583 Superconductingmaterials, 481 type 1,482 type 11, 482 Superconductivity, 480, 482, 641 tunneling, 483 Superconductor, 641 Superconductor film, thermal cycling, 437 Superlattice, 661-662 compositional, 663 doping, 663 strained layer, 664 table of systems,... deposited by, 140 In,O,:Sn, 515 In20,:Sn02(ITO), transparent conductor, 517 Ids, CVD, 154 proPertjes, 325 Index of absorption, 509 Index of refraction, 509, 513 Indirect energy band gap, 324, 326 Induced dipole, 514 Inelastic collisions, 108 InGaAs, MBE, 339 quantum well, 664 InP, 330, 350 CVD, 154 MBE, 339 properties, 325 InSb, properties, 325 Instantaneous stress, 423 Insulating films, 465 Integrated optics,... semiconductors, 515, 517 Optical recording, 650-651, 653 Optical waveguides, 655-656 channel, 657 embedded, 657 thin film, 658 Optoelectronics, 323 Orbitals, sp, 636, 640 Ostwald ripening, 214- 215 Outgassing, 74 Oval defect, 321 Oxidation, 396, 581 -582 CVD, 150 kinetics, 397 Oxidation rate, 582 inverse logarithmic, 583 logarithmic, 583 Oxidation wear, 574 Oxygen, content in films, 96 PzO,, CVD, 150 Packing... thermodynamics of CVD, 158 Si-Au, amorphous, 605 Si-Bi, 604 Si,N,, 151 conduction, 470-47 1 Sic, 161, 547 CVD, 150 Silicide, Kirkendall effect, 369 Silicides, 389 formation (table), 390 ion beam mixing, 618 Siliciding, 580 Silicon nitride, 181 CVD, 182 properties, 182 Silicon on insulator, LEGO,333 Silicon on insulator (SOI), 3 10 SIMOX, 623 SIMS, 250, 275, 296-297 spectrometer, 298 static, 299 Sintering, 214- 215. .. deposition 642 thermal stability 678 Hillock, formation, 438 Hillocks, 678 Homoepitaxy , 307 Homogeneous nucleation, 200 Hooke’s law, 16,407,418, 569 Hot mirror, 537 Hot wall reactor, 175 Hydride process, CVD, 153 Hydrogen, PECVD films, 183 Hyperfine magnetic field, 492 Hysteresis, magnetic, 487, 493 single domain, 498 I IAD, 137, 521 films deposited by, 138 ICB, 138-139 cluster nucleation, 144 films deposited... index, 329 AIGaAs-GaAs, laser, 323 Alloy films, 374 AISb, properties, 325 Aluminum, vapor pressure, 82 Aluminizing, 580, 581 Amorphous carbon, 637 f l ,resistivity, 238 im films, 653 films, Au-Co, Ni-Zr, 236 phase, 609 si, 602 solid, 8 thin films, 235 zone, 612 Amorphous-crystalline, optical recording, 654 Analog grading, 667 Analytical techniques (table), 250 Anisotropy, magnetic, 486-487 perpendicular,... 480 superconducting materials, 48 1 Critical nucleus, 200 Critical temperature, 480 superconducting materials, 48 1 Critical wave length, 514 Cross-tie wall, 494 energy, 495 Crucible source, evaporation, 98 Cryopump, 68 schematic, 69 Crystal oscillator, 253, 263 film thickness, 264 crystal structure, Bravais lattice, 3 Diamond cubic, 4 rock salt, 4 zinc blende, 4 CSVT, materials synthesized by, 166 CU,... silicon nitride, 182 LSS theory, 611, 615 Lubrication, 572, 578 M Laminar flow 56, 163 Magnetic bubbles, 499 Laser, 323, 540, 589-590, 593, 595-596, size, 499 598-600,602,607, 609,650-651 speed, 500 cw, 592 Magnetic disk, 645 heating, 597 Magnetic domains 489,494 interaction time, 590 Magnetic film, 649 power density, 590 Magnetic materials, pulsed, 592 hard, 487,488 Q-switched, 592 soft, 487,488 sources, . window in the SiO, is opened to the bare Si surface by photolithography methods. If the sides of the square lie along [l IO] directions, sketch the shapes of the holes produced in the Si. Consider the web coating of a polymer film of thickness, d,, by a magnetic alloy of thickness, d,, in the manufacture of magnetic tape. The alloy film is sputtered and the thermal. all base electrodes. A further materials problem aired in Section 9.5.3 concerns barrier mechan- ical stability during thermal cycling. The use of Sb in the Pb electrode (Fig. 14-22)