Joost
J. Vlassak
Gordon McKay Professor of
Materials Engineering
Education
Burgerlijk Ingenieur,
1989, Metallurgical Engineering,
M.S., 1990, Materials Science,
Ph.D., 1994, Materials Science,
Contacts
Office: SEAS,
Pierce
Hall 311,
Phone: (617)
496-0424
Fax: (617) 495-9837
E-mail: vlassak"at"esag"dot"harvard"dot"edu
Lab and Group Members
Academic Interests
Materials Engineering
The use of thin films in
integrated circuits and micromachined devices has
created a strong interest in the mechanical properties of thin-film materials
and materials in small volumes. As the complexity of these systems increases,
the materials used in them have to meet more stringent requirements. For
example, until recently integrated circuits consisted of relatively few
materials: single and polycrystalline silicon, various aluminum alloys, silicon
oxides and nitrides of varying composition, as well as barrier films and silicides. Requirements for better electrical performance,
however, have led to the incorporation of a host of new materials including Cu,
silicon carbo-nitrides, and organosilicate-based
dielectrics with low dielectric constants. Integration of these new materials
into integrated circuit process flows poses interesting challenges for engineers
in research and development organizations. A good understanding of the
mechanical properties of these materials and of the interfaces between them is
critical to the successful integration of these materials. Other applications
where mechanical properties of thin films play a critical role include
micro-electromechanical systems (MEMS), electronic packaging, and data storage
(e.g., magnetic storage media).
Professor Vlassak has
developed new experimental techniques for studying the mechanical behavior of
thin films. He has investigated the effect of elastic anisotropy on stiffness
measurements on small volumes of materials using nano-indentation
techniques and has developed a technique for measuring the adhesion of brittle
coatings to ductile substrates using plane-strain indentation. He has also
developed a method for measuring stress-strain curves of freestanding films
using silicon micro-machining techniques that can be applied to films as thin
as a few tens of nanometers.
Current experimental research
projects focus on the effects of microstructural
length scales on the mechanical behavior of thin metal films, on the effect of
environmental species on the adhesion and delamination of multilayered
structures containing low-k dielectrics, on the shape memory effect in thin
films of NiTi, Fe-Pd and Heusler-type
alloys, and on various thin-film combinatorial approaches to alloy development.
Recently, Professor Vlassak's group developed a micromachined parallel nano-differential
scanning calorimeter for the thermal analysis of complex nano-scale
material systems.
Theoretical work
includes a new model for chemical mechanical polishing (CMP) based on contact
mechanics, channel cracking in films on substrates of finite thickness, and
various analyses of the effects of substrate properties and film porosity on
nanoindentation of thin films.
Projects
Professor Vlassak's research group
is involved in both experimental and theoretical projects in thin-film mechanics,
materials science and related areas. Some of our current projects are listed
below:
1. Fracture in Multi-Layered Structures etc. (Youbo Lin,Han Li)
2. Mechanical Behavior and Microstructure of Metallic Thin Films etc. (Yong Xiang)
3. Size Effects in Ti-Ni Shape Memory Alloy Films. (Xi Wang)
4. Micromachined devices for combinatorial materials analysis. (Patrick McCluskey, Jun-Hyun Han)
5. Ferromagnetic Shape Memory
Thin Films. (Patrick McCluskey, Jun-Hyun Han, Prita Pant)
6. Mechanical behavior of hybrid organic/inorganic systems.
7. Problems in Anisotropic Contact Mechanics.
8. Chemical Mechanical Polishing as a Contact Problem.
Courses Offered
Engineering
Sciences 120. Introduction to the Mechanics of Solids
Catalog Number: 1493 Half
course (spring term). M., W., F., at 10. EXAM GROUP: 3
A first course in the mechanical sciences which
introduces elements of continuum mechanics and explains how materials and
structures stretch, bend, twist, shake, buckle, and break. Stress-strain
behavior of materials. Statically determinate and
indeterminate structures. Stress and strain, equations
of motion or equilibrium, strain-displacement relations. Stress waves. Torsion. Beam theory with applications to beam deflections,
vibrations, and buckling. Four laboratory sessions required.
Prerequisite: Physics 11a or 15a, and Applied Mathematics 21a or
Mathematics 21a (previously) and Applied Mathematics 21b or Mathematics 21b
(previously or concurrently).
Applied Physics 190. Materials Physics
Catalog Number: 1087 Half course (spring term). Tu., Th., 10:00-11:30.
EXAM GROUP: 12, 13
Introduces undergraduates in Engineering and Physics to the scientific basis of
our understanding of the structure and properties of materials. Topics to be
covered include chemical bonding and its relation to structure;
crystallography; diffraction; defects in crystals and their effects on material
behavior; electrical, thermal and mechanical properties.
Prerequisite: Thermodynamics (Engineering Sciences 181, Physics 181, or
equivalent), Physics 11a and b, or Physics 15a and b, and Applied Mathematics
21a and b or Mathematics 21a and b.
Engineering Sciences 190. Introduction to Materials Science
Catalog Number: 6973 Half course (spring term). Tu., Th., 10:00. EXAM
GROUP: 12, 13
Introduction to the structure and properties of materials. Bonding
between atoms.
Prerequisite: Engineering Sciences 181 or equivalent, Physics 11 or 15,
and Applied Mathematics 21a,b or Mathematics 21a,b.
Engineering
Sciences 240. Solid Mechanics
Catalog Number: 2984 Half
course (fall term). M., W., F., at 10 and a weekly section to
be arranged. EXAM GROUP: 3
Foundations of continuum mechanics, development of elasticity theory, and
introduction to plasticity and creep. Elastic waves. Basic
elasticity solutions. Variational principles.
Prerequisite: Applied Mathematics 105b or equivalent; introduction to
solid mechanics at the level of Engineering Sciences 120, or Earth and
Planetary Sciences 108 or 166, or Applied Physics 293.
Engineering Sciences 242r. Solid Mechanics:
Advanced Seminar
Catalog Number: 5379 Half
course (spring term). Tu., Th., 10-11:30. EXAM GROUP: 12, 13
Topics in 2001-02. The mechanics of films and multilayers:
deformation, cracking and delamination. Residual stresses in thin films and
their origin. Micron scale plasticity and its applications.
Prerequisite: Engineering Sciences 240.
Engineering Sciences 246. Plasticity and Finite Deformation
Catalog Number: 4271 Half course (fall term). Tu., Th., 2:30-4. EXAM
GROUP: 16,17.
Phenomenological theories for strain hardening materials;
flow and deformation theories. Variational principles and other general theorems. Mechanisms
of plastic deformation, physical theories for strain hardening materials, and polycrystals. Ideal plasticity.
Boundary value problems, plastic collapse, buckling of
structures.
Prerequisite: Engineering Sciences 240, or equivalent
Engineering Sciences 247. Fracture
Mechanics
Catalog Number: 7152 Half
course (fall term). Tu., Th., 2:30. EXAM GROUP: 16, 17
Fundamentals of fracture with applications in materials and structural
mechanics. Micromechanics of fracture in ceramics, metals, and polymers.
Fracture of composite materials. Interfacial fracture mechanics. Fatigue crack
propagation.
Prerequisite: Engineering Sciences 240 or equivalent.
Selected Publications
72.
|
Xi Wang and Joost Vlassak, "The effect of film thickness on the martensitic transformation in equi-atomic NiTi thin films constrained by substrates", submitted (2009).(Download)
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71.
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Han Li, Ting Y.Tsui and Joost Vlassak, "Water diffusion and fracture behavior in nano-porous low-k dielectric film stacks",Journal of Applied Physics,106, 033503 (2009).(Download)
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70.
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Youbo Lin, Ting Y.Tsui and Joost Vlassak, "Adhesion degradation and water diffusion in nanoporous organosilicate glass thin film stacks", submitted (2009).(Download)
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69.
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Nanshu Lu, Xi Wang, Zhigang Suo, Joost Vlassak, "Failure by simultaneous grain growth, strain localization, and interface debonding in metal films on polymer substrates",Journal of Materials Research, 24(2) 379-385 (2009).(Download)
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68.
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Han Li and Joost J. Vlassak, "Determining the elastic modulus and hardness of an ultra-thin film on a substrate using nanoindentation",Journal of Materials Research, 24(3) (2009). (Download)
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67.
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Frank L. Wei,Chee Lip Gan,Tam Lyn Tan,Christine S. Hau-Riege,Amit P. Marathe,Joost J. Vlassak,and Carl V. Thompson, "Electromigration-induced extrusion failures in Cu/low-k interconnects", Journal of Applied Physics,104, 023529(2008). (Download)
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66.
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Youbo Lin, Yong Xiang, Ting Y. Tsui, and Joost J. Vlassak, "PECVD Low-Permittivity Organosilicate Glass Coatings: Adhesion, Fracture and Mechanical Properties", Acta Materialia, 56(17), 4932-4943 (2008). (Download)
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65.
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Han Li, Youbo Lin, Ting Y.Tsui and Joost Vlassak, "The effect of porogen loading on the stiffness and fracture energy of brittle organosilicates", Journal of Materials Research, 24(1) 107-116 (2009). (Download)
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64.
|
H.-J. Kim, J.-H. Han, R. Kaiser, K.H. Oh, J.J. Vlassak, "High-throughput analysis of thin-film stresses using arrays of micromachined cantilever beams", Review of Scientific Instruments, 79(4) 045112 (2008). (Download)
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63. |
Nanshu Lu, Xi Wang , Zhigang Suo and Joost Vlassak, "Metal films on polymer substrates stretched beyond 50%", Applied Physics Letter, 91, 221909 (2007). (Download)
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62. |
X. Wang , M. Rein, J.J. Vlassak, " Crystallization kinetics of amorphous equiatomic NiTi thin films: Effect of film thickness ", Journal of Applied Physics, 103, #023501 (2008). (Download)
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61. |
X. Wang , Y. Bellouard, Z.Y Xue, J.J. Vlassak, " Thermal modeling of laser-annealing-induced crystallization of amorphous NiTi thin films ", Applied Physics A,90,689-694 (2007) . (Download)
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60. |
Huazhi Li,Damon B. Farmer,Roy G. Gordon,Youbo Lin,Joost Vlassak, "Vapor Deposition of Ruthenium from an Amidinate Precursor", Journal of the Electrochemical Society, 154, D642-D647 (2007). (Download)
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59. |
Manhong Zhao, Xi Chen, Yong Xiang, Joost J. Vlassak, Dongyun Lee, Nagahisa Ogasawara, Norimasa Chiba, Yong X. Gan, "Measuring elastoplastic properties of thin films on an elastic substrate using sharp indentation", Acta Materialia, 55(18) 6260-6274 (2007). (Download) |
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58. |
Yong Xiang, James McKinnell, Wie-Ming Ang, and Joost J. Vlassak, "Measuring the fracture toughness of ultra-thin films with application to AlTa coatings", International Journal of Fracture, 144(3),173-179 (2007). (Download) |
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57. |
Jae-Hyun
Kim, and Joost J. Vlassak, "Perturbation
analysis of an undulating free surface in a multi-layered structure", International Journal of Solids and
Structures, 44, 7924-7937 (2007). (Download) |
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56. |
X. Wang, Z.Y. Xue,
Y. Bellouard, J.J. Vlassak, "Laser annealing of
amorphous Ni-Ti shape memory alloy thin films", Shape
Memory and Superelastic Technologies (SMST)
Proceedings, in
press. (Download) |
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55. |
D. Passeri, A. Bettucci, M. Germano, M. Rossi,
A. Alippi, A. Fiori, E. Tamburri, S. Orlanducci, M.L. Terranova, and J.J. Vlassak, "Local indentation
modulus characterization via two contact resonance frequencies atomic force
acoustic microscopy", Micorelectronic
Engineering, 84(3),490-494 (2007). (Download)
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54. |
Jae-Hyun
Kim, and Joost J. Vlassak, "T-Stress Of a
Bi-Material Strip Under Generalized Edge Loads", International Journal of Fracture (Letters section), 142(3-4),315-322
(2006). (Download) |
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53. |
Youbo Lin, Ting Y. Tsui, and Joost J. Vlassak, "Water diffusion and fracture in
organosilicate glass film stacks", Acta Materialia, 55, 2455-2464 (2007). (Download) |
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52. |
Patrick James McCluskey,
and Joost J. Vlassak, "Parallel nano-Differential Scanning Calorimetry:
A New Device for Combinatorial Analysis of Complex nano-Scale
Material Systems", Materials
Research Society Symposium Proceedings, 924E, (2006). (Download) |
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51. |
Y. Kim, P. Chen, M. J. Aziz,
D. Branton, and J.J. Vlassak, "Focused Ion
Beam Induced Deflections of Freestanding Thin Films", Journal of Applied Physics, 100, 104322 (2006). (Download) |
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50. |
Y. Xiang and J.J.
Vlassak, "Bauschinger and size effects in
thin-film plasticity", Acta Materialia, 54, 5449-5460 (2006). (Download) |
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49. |
L. Nicola, Y. Xiang, J.J. Vlassak, E. Van der Giessen,
and A. Needleman, "Plastic deformation of freestanding thin films: experiments
and modeling", Journal
of The Mechanics and Physics of Solids, 54 (10), 2089-2110
(2006). (Download) |
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48. |
Youbo Lin, Ting Y.
Tsui, and Joost J. Vlassak,
"Octamethylcyclotetrasiloxane-based Low-permittivity Organosilicate
Coatings: Composition, Structure and Polarizability", Journal of The Electrochemical Society, 153
(7), F144-F152 (2006). (Download) |
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47. |
Ting Y. Tsui, Andrew
J. McKerrow, and Joost J. Vlassak, "The Effect
of Water Diffusion on the Adhesion of Organosilicate Glass Film Stacks",
Journal of The Mechanics and
Physics of Solids, 54 (5), 887-903 (2006). (Download) |
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46. |
Zhigang Suo, Joost Vlassak, and Sigurd
Wagner, "Micromechanics of macroelectronics",
China Particuology, 3
(6), 321-328 (2005). (Download) |
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45. |
Ting Y. Tsui, Joost J. Vlassak, Kelly Taylor, Andrew J. McKerrow, and
Robert Kraft, "Effects of Absorption of Water and Other Reactive Species
on the Fracture Properties of Organosilicate Glass Thin Films", AMC proceedings,
695-700 (2005). (Download) |
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44. |
Xi Wang, and Joost.J. Vlassak, "Crystallization Kinetics of
Amorphous NiTi Shape Memory Alloy Thin Films",
Scripta Materialia, 54,
925-930 (2005). (Download) |
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43. |
X. Chen, Y. Xiang, and J.J. Vlassak, "A novel technique of
measuring the mechanical properties of porous materials by nanoindentation:
with application to low-k dielectric thin films", Journal of Materials Research, 21
(3), 715-724 (2006). (Download) |
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42. |
Y. Xiang, X. Chen, T.Y. Tsui, J.-I. Jang, and J.J. Vlassak,
"Mechanical properties of porous and fully dense low-k dielectric thin films
measured by means of nanoindentation and the plane-strain bulge test
technique", Journal
of Materials Research, 21 (2), 386-395 (2006). (Download) |
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41. |
Y. Xiang, T.Y. Tsui, and J. J. Vlassak, "The Mechanical
Properties of Freestanding Electroplated Cu Thin Films", Journal of Materials Research, 21
(6), (2006). (Download) |
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40. |
Yong Xiang, Teng Li, Zhigang Suo, and Joost J. Vlassak, "High ductility of a metal film
adherent on a polymer substrate", Applied Physics Letters, 87, 161910 (2005).
(Download) |
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39. |
X. Wang, Y. Bellouard, and J. J. Vlassak, "Laser Annealing of
Amorphous NiTi Shape Memory Alloy Thin Films to
Locally Induce Shape Memory Properties", Acta Materialia, 53
(18), 4955-4961 (2005). (Download) |
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38. |
Ting Y. Tsui, Andrew
J. McKerrow and Joost J. Vlassak, "Constraint
Effects on Cohesive Failures in Low-k Dielectric Thin Films", Materials Research Society Symposium
Proceedings, 863, 3 (2005). (Download) |
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37. |
Ting Y. Tsui, Andrew
J. McKerrow and Joost J. Vlassak, "Constraint
Effects on Thin Film Channel Cracking Behavior", Journal of Materials Research, 20
(9), 2266-2273 (2005). (Download) |
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36. |
Y. Xiang and J.J.
Vlassak, "Bauschinger Effect in Thin Metal
Films", Scripta Materialia,
53, 177-182 (2005). (Download) |
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35. |
Y. Xiang, X. Chen,
and J.J. Vlassak, "The plane-strain bulge test for thin films", Journal of Materials Research, 20
(9), 2360-2370 (2005). (Download) |
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34. |
Zhengwen Li,
Roy G. Gordon, Damon B. Farmer, Youbo Lin and Joost
Vlassak, "Nucleation and Adhesion of ALD Copper on Cobalt Adhesion
Layers and Tungsten Nitride Diffusion Barriers", Electrochemical and
Solid-State Letters 8 (7), G182-G185 (2005). (Download) |
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33. |
Y. Sugimura, |
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32. |
Young-Shin Jun, Treavor
A. Kendall, Scot T. Martin, Cynthia M. Friend and Joost
J. Vlassak, "Heteroepitaxial Nucleation and
Oriented Growth of |
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31. |
Joost J.
Vlassak, Youbo Lin and Ting Y. Tsui, "Fracture of Organosilicate Glass
Thin Films: Environmental Effects", Materials Science and Engineering
A 391, 159-174 (2005). (Download) |
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30. |
Fadila Khelfaoui, Yves Bellouard,
Thomas Gessmann, Xi Wang, Joost
Vlassak and Moustapha Hafez, "An Investigation
of The Oxidation of Laser and Furnace-Annealed Sputter-Deposited Ni-Ti Thin
Films Using Reflectivity Measurements", SMST 2004, |
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29. |
Yuki Sugimura, Tzahi
Cohen-Karni, Patrick McCluskey
and Joost Vlassak, "Fabrication and
Characterization of Fe-Pd Ferromagnetic Shape-Memory Thin Films", MRS
Symposium Proceedings 785, D7.4.1 (2004). (Download) |
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28. |
Yong Xiang, Ting Y. Tsui, Joost J.
Vlassak and Andrew J. McKerrow, "Measuring the Elastic Modulus and
Ultimate Strength of Low-k Dielectric Materials by means of the Bulge
Test", Proceeding of the International Interconnect
Technology Conference (IITC), IEEE, pp. 133-135, (2004). (Download) |
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27. |
Youbo
Lin, Joost J. Vlassak, Ting Y. Tsui and Andrew J.
McKerrow, "Subcritical Delamination of Dielectric and Metal Films from
Low-k Organosilicate Glass (OSG) Thin Films in Buffered pH Solutions", MRS
Symposium Proceedings 795, 93-98 (2004). (Download) |
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26. |
Yong Xiang, Joost J. Vlassak, Maria
T. Perez-Prado, Ting Y. Tsui, Andrew J. McKerrow,
"The effects of passivation layer and film
thickness on the mechanical behavior of freestanding electroplated Cu thin
films with constant microstructure", MRS Symposium Proceedings 795,
417-422 (2004). (Download) |
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25. |
Xi
Wang, Ann Lai, Joost J. Vlassak and Yves Bellouard, "Microstructure Evolution of On-substrate
NiTi Shape Memory Alloy Thin Films", MRS
Symposium Proceedings 795, 275-280 (2004). (Download) |
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24. |
J. J.
Vlassak, "A model for chemical-mechanical polishing of a material
surface based on contact mechanics", Journal of the Mechanics and
Physics of Solids 52, 847-873
(2004). (Download) |
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23. |
Youbo
Lin, Joost J. Vlassak, Ting Y. Tsui, Andrew J.
McKerrow, "Environmental effects on subcritical delamination of
dielectric and metal films from organosilicate glass (osg)
thin films", MRS Symposium Proceedings 766. E9.4 (2003). (Download) |
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22. |
J. J. Vlassak, M. Ciavarella, J.
R. Barber, X. Wang, "The indentation modulus of elastically anisotropic
materials for indenters of arbitrary shape", Journal of the Mechanics
and Physics of Solids 51 (9), 1701-1721 (2003). (Download) |
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21. |
J. J. Vlassak, "Channel cracking in thin films on
substrates of finite thickness", International Journal of Fracture
119 (4), 299-312 (2003). (Download) |
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20. |
M. T. Perez-Prado, J. J.
Vlassak, "Texture evolution of Cu thin films during annealing", Materials
Science Forum 408 (4), 1639-1644 (2002). |
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19. |
M. T. Perez-Prado, J. J.
Vlassak, "Microstructural evolution in
electroplated Cu thin films", Scripta
Materialia 47 (12), 817-823 (2002). (Download) |
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18. |
Y. Xiang, X. Chen, J. J.
Vlassak, "The mechanical properties of electroplated Cu thin films
measured by means of the bulge test technique", Materials Research
Symposium Proceedings 695, L4.9 (2002) (Download) |
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17. |
M. Ciavarella, G. Demelio, M. Schino, J. J.
Vlassak, "The General 3D-Hertzian Contact Problem for Anisotropic
Materials", in Experimental Techniques and Design in Composite
Materials 5, Key Engineering Materials 221-222. 281-292 (2002). |
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16. |
J. J. Vlassak, "A contact-mechanics based model for
dishing and erosion in chemical-mechanical polishing", Materials
Research Symposium Proceedings 671,
M4.6.1 (2001).
(Download) |
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15. |
X. Chen, J. Vlassak, "A numerical study on the
measurements of thin film mechanical properties by means of
nanoindentation", J. Mater. Res.
16 (10), 2974-2982 (2001). (Download) |
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14. |
T. Y. Tsui, J. Vlassak, W. D. Nix, "Indentation
plastic displacement field: Part I. The case of soft films on hard
substrates", J. Mater. Res. 14 (6), 2204-2209 (1999) |
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13. |
T. Y. Tsui, J. J. Vlassak, W. D.
Nix, "Indentation plastic displacement field: Part II. The case of hard
films on soft substrates" J.
Mater. Res. 14 (6), 2196-2203
(1999) |
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12. |
K. W. McElhany,
J. J. Vlassak, W. D. Nix, "Determination of indenter tip geometry and
indentation contact area for depth-sensing indentation experiments", J. Mater. Res. 13 (5), 1300-1306 (1998) |
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11. |
J. J. Vlassak, T. Y. Tsui, W. D. Nix, "A new
technique for visualizing the displacement field of indentations: the case of
a soft film on a hard substrate", Materials Research Symposium
Proceedings 505, 71-76 (1998) |
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10. |
S. Hsu, M. Dusa, J. Vlassak, C. Harker, M. Zimmerman, "Characterization and
optimization of overlay targets for W CMP", Proceedings of the SPIE,
360-370 (1998) |
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9. |
J.J. Vlassak, M. D. Drory, W. D.
Nix, "A simple technique for measuring the adhesion of brittle films to
ductile substrates with application to diamond-coated titanium", J. Mater. Res. 12 (7), 1900-1910 (1997) |
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8. |
R. P. Vinci, J. J. Vlassak, "Mechanical behavior of
thin films", Ann. Rev. Mat. Sc. 26, 431-462 (1996) |
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7. |
V. M. Paviot,
J. J. Vlassak, and W. D. Nix, "Measuring the mechanical properties of
thin metal films by means of bulge testing of micromachined
windows", Materials Research Symposium Proceedings 356, 579-584 (1995) |
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6. |
J. J. Vlassak, W. D. Nix,
"Measuring the elastic properties of anisotropic materials by means of
indentation experiments", J. Mech.
and Phys. of Solids 42 (8),
1223-1245 (1994) (Download) |
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5. |
J. J. Vlassak, W. D. Nix, "Indentation
modulus of elastically anisotropic half spaces", Phil. Mag. A 67 (5), 1045-1056
(1993) |
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4. |
M. K. Small, J. J. Vlassak, S.
F. Powel, B. J. Daniels and W. D. Nix, "Accuracy and reliability of
bulge test experiments", Materials Research Symposium Proceedings,
308, 159-164 (1993) |
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3. |
J. J. Vlassak, W. D. Nix,
"A new bulge test technique for the determination of Young's modulus and
Poisson's ratio of thin films", J.
Mater. Res. 7 (12), 3242-3249
(1992) |
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2. |
M. K. Small, J.J. Vlassak and W.D.
Nix, "Re-examining the bulge test: methods for improving accuracy and
reliability", Materials Research Symposium Proceedings, 239, 493-498 (1992) |
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1. |
J. J. Vlassak, T. Nakayama, T.
J. Konno and W. D. Nix, "Structure and mechanical properties of Fe/Zr multilayers", Materials
Research Symposium Proceedings 239,
493-498 (1992) |
This material in this website is based upon work supported by the National Science Foundation under Grants No. 0133559, 0215902, and 9809363. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.
Last updated: 5/20/2007