The Materials Science of Thin Films 2011 Part 15 ppt

Much remains to be said about other thin-film applications includ- ing displays, sensors, and assorted electronic, optical, thermal, and surface acoustic devices.. Three thin-film compu

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

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

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 ( E T ) If the film thickness if d , the distance

680 Emerglng Thin-Film Materials and Applications

between walls is d,, and

EM = 1.07 x 1 O S M ~ d , (in mks units)

a Show that

d E~ = E,- + 1.07 x 105~:d,

d w

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

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 A E , 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?

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,

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

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

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

1 Bar = 0.987 Atm = 750 Torr

10’’ dynes/cm2 = lo9 N/m2 = lo9 Pa = 146000 psi

1 erg = 1 dyne-cm = l o p 7 Joule

1 eV = 1.602 x

1 eV/atom = 23060 callmole

1 Weber/m2 = l o 4 Gauss = 1 Tesla

1 Poise (P) = 1 dyne sec/cm2

erg = 1.602 x lopi9 Joule

68 7

Ag-Au-Pb, x-ray diffraction, 274

Ag-Li, residual stress, 415

B

Ball bearings, 577-578 Ballistic transport, 673 Band gap engineering, 668-670 Barrier height, 393, 468

Barrier limited conduction, 466

Bamer oxide, 677

BC, 547 BCS theory, 482 Beamsplitter, 532 Bending, 418 Bias sputtering, 129 Biaxial stress, 418, 423-424 Bilayer metals, ion beam mixing, 618 Bloch wall, 494

energy, 495

BN, CVD, 150 Bond coat, 584 Bonding, 14 covalent, 18 ionic, 17 metallic, 16 van der Waals, 19 Borides, 551 Boronizing, 580

Borophosphosilicate glass, 177 Boundary layer, 163, 165 Bragg’s law, 7, 343-344 Bravais lattice, 2-3 Broadband filter, 539 Bubbles, magnetic, 499, 501 Bulge testing, 410

Bulk diffusion, 224 Bulk limited conduction, 467 Burger’s vector, 11

C

C-V characteristic, 476 Cantilever beam, stress measurement, 42 1

Capillarity, 198 Carbides, 551 alloy, 558 Carbon, amorphous, 637 ion beam, 637 Carburizing, 580-581 CARIS, 253, 258

Chemical reaction, thermodynamics, 22

Chemical reaction rate, 39

Chemical vapor deposition (CVD), see CVD

Compensation point recording, 651

Complementary error function (Erfc), 35

lattice constant, 328 materials, 324 properties, 325 table, 325 Compounds, AuA1,-Au,AI, 377 Computer memory, 488 magnetic bubble, 501 SQUID, 675 thin film, 500-501 Computer simulation, film morphology, 230 microstructure, 232 complete, 210 extreme incomplete, 213 incomplete, 210 Conductance, 54 cold trap assembly, 59 orifice, 57

various shapes, 58 barrier limited, 465 bulk limited, 465 insulators, 465 intrinsic, 466

ionic, 466

mechanisms, 466 metals, 456 Poole-Frenkel, 466

Schottky emission, 466

Si,N,, 470 space charge limited, 466 tunneling, 466

Conduction band offset, 665 Cone formation, 621-622 Conformal coverage, 93 Constitutional supercooling, 606

Convection, 167 Cooper pairs, 483 Copper, structure, 3

Curie point writing, 651

Current-voltage characteristics, tunneling, 484

D

de Broglie, 662, 670 Debonding, 569 Defectless flow, 434 Defects in solids, 10 Deformation map, 436 Delamination, 569 Demagnetizing field, 486 Density, 232, 233 Depletion, 475 Deposition rate, 95 nucleation, 203 Desorption, 201, 340

Diamond, 27, 547, 635-636, 638, 640

properties, 325 table, 639 Diamond films, 638

applications, 640

properties, 639 wear, 573

Diamondlike, carbon, 637, 640 Dielectric breakdown, 477-479 Dielectric isolation, 333 Dielectric mirror, 540 Dielectric stack, 534 Dies, 620

Diffraction, optical simulation, 239 Diffusion, 33, 164, 355, 580 alloy films, 374

atomistic, 36

Au in Au, 364-365 compounds, 367 Cr-Cu-Au, 313

Domains, in garnet films, 499

Edge dislocation, motion, 12 EDX, see Energy dispersive x-ray analysis

Effusion cell, 336 Electrical conduction, insulators, 465

Elastic collisions, IO7 Elastic strain energy, 316 Elasticity, 405

Electrical properties, 451 Dependence on electrodes, 453 Dependence on film preparation, 452 Electro-optical phase modulator, 657 Electromigration, 379, 383-384

393

damage, 382 film life, 381 energy bands, 19

energy levels, 14 free, 16 mean free path, 457 Electron attachment, 109

Electron beam evaporation, 99 Electron beam induced current (EBIC), 269 Electron beam source, 100

Electron current, plasma, 106

Electron cyclotron resonance (ECR), 184

Electron microprobe, 283 Electron motion, Electron,

in magnetic and electric fields, 124 magnetic and electric fields, 125

grain boundary, 461 Electron scattering, 457, 459 Electron spectrometer, AES, XPS, 284 Electron spectroscopy, 277

Electronic packaging, 404 Electronic stopping power, 611 Ellingham diagram, 24-25

Ellipsometry, 258-260 film thickness, 253 Endothermic reaction, 173 Energy,

level, 14

of adhesion, 439 Energy band, diagrams, 19-20

694

Index

Energy band gap, 514

Energy dispersive x-ray (EDX) analysis, 269,

Energy gap, 20

superconductivity, 483

Energy levels, 665

Energy loss, ions, 610-61 1

Energy transfer function, 108

Eutectics, ion beam mixing, 618

Evaporated films, zone structure, 225 Evaporated metal films, internal stress, 422 Evaporation, 88, 102-103, 131, 132

AI-Cu, 86

alloys, 85

compounds, 84-85 early aplications, 79 electron beam, 99 fdm uniformity, 90

geometry, 87 hardware, 97 materials characteristics, 102- 103 magnetic film, 649

power density, 99 reactive, 96

uniform deposition, 92 Evaporation flux, 81 Evaporation rate, 81

Evaporation source, cosine dependence, 88 refractory metal, 97 tungsten, 97 Exchange energy, 486 Excitation, 108 Exothermic reaction, 173

F

Fabry-Perot, 507, 540 Faraday effect, 498 Fatigue wear, 573

Fe, 598 Fermi energy, 20 Fermi level, 2 1 Ferromagnetism, 485 Ferromagnets, 485

amorphous, 492

Fick’s law, gas diffusion, 165 Field energy density, magnetic, 485 Film coverage, 93

Film deposition, superconductors, 642 Film growth, 197

Mossbauer spectra, 493

diffusion limited, 397 reaction limited, 397 Film growth rate, CVD, 168 Film purity, 95

properties, 325 Garnet, 498 Gas diffusion, 165

Gas flow, 56

Gas impingement rate, 53 Gas transfer pump, 62 Gas transport, 55, 162 Gas velocities, 49-50 GaSb, Properties, 325 Gases in films, 96

GdCo, 235

Ge,

CVD, 151

properties, 325 Ge-Si, phase diagram, 28

M e , 235 GeSi-Si, 309 epitaxy, 3 18 superlattice, 664

Gibbs Phase Rule, 26, 161 Gibbs-Thompson equation, 2 15 Glow discharge, 101

Glue layer, 373 Graded base transistor, 670 Grain boundaries, 10 Grain boundary,

dc, 104

diffusion, 358, 361, 374 dislocation model, 12 electron scattering, 461 Kirkendall effect, 375 stress, 431

Grain growth, 227 Grain size, 10 Grain stmcture, simulation, 230 Graphite, 636, 639

Gray filter, 538 Griffith crack theory, 568

Growth kinetics, CVD, 167, 171

Guided mode, 656

Hagen-Poiseuille flow, 164 Hall-Petch equation, 409, 564 Hard carbon, 637, 649

Hydrogen, PECVD films, 183

Hyperfine magnetic field, 492

films deposited by, 138

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, 654-656 devices, 657-658

materials, 659

rf spectrum analyzer, 660

Interfaces, film-substrate, 440

Interference, 528 optical, 507 Interference pattern, stress, 424 Interferometry, 253

FECO, 255

film stress, 421

Tolanslq method, 254 transparent films, 256 Internal stress, 413, 416 evaporated metal fdms, 422 measurement techniques, 421 sputtered films, 428 Intrinsic conduction, 466,469 Intrinsic stress, 425 metals, nonmetals, (table), 426 recrystallization, 430 temperature dependence, 427 theories, 429

thickness dependence, 426 Inversion, 476

Ion assisted deposition (IAD), see IAD

Ion beam, 622 Ion beam evaporation, 135 Ion beam mixing, 617 Ion beam modification, 623 Ion beams, 610

Ion bombardment, 622 Ion channeling, 296 Ion current, plasma, 106

Kinetic energy, sputtered metals, 116

Kinetic theory of gases, 47

Lateral epitaxial growth, 334

Metal carbides, alloy, 558

Metal compounds, hard, 551

Ag, Al, 513 Misfit dislocations, 322

Mo, CVD, 149 MOCVD, 186-187 superlattice, 663 composition, 613 mechanically functional surfaces, 618

of Si, 622 structure, 610 Modification

Modification of surfaces, 589 Modulation doping, 667-668 Molecular beam epitaxy (MBE), see MBE Molecular field, 491

Molecular velocities, 48 MOMBE, 338 Monolayer gas coverage, 54

Morphology, columnar, 228 MOS capacitance, 476 MOS structure, 475 Mossbauer effect, 492-493 Multilayer coatings, 559-560 Multilayer optical films, 53 1

Multilayers, 668 Multiple beam interferometry, 253

M o l a l a r flow, 56-57

N

Na vapor lamp, 536 Nanoindenter, 412-413, 564 Narrow band filter, 540

NbN, 675

N h l wall 494 energy, 495 Nernst-Einstein equation, 39, 356, 435 electromigration, 383

Neutral filter, 538

Ni, 598, 601 CVD, 149 implanted in stainless steel, 615 Ni-Si, 391

Ni-Zr, 236 Ni,Si, 391

NiA1, 581

Nisi, 391 Nisi,, 391 Nitrides, 551 alloy, 558 TEM micrograph, 239