Thése CIFRE Atom Probe ST IM2NP Septembre 2009

Magali Gregoire

Informations

• Publié par: Cipot
• Nombre de lectures: 296
• Langue: English

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Proposition de thèse CIFRE

IM2NP-Institut Matériaux Microelectronique
Nanosciences de Provence (Marseille) /
STMICROELECTRONICS (Crolles)




La sonde atomique tomographique : applications
aux dispositifs CMOS avancés sub-45nm



Directeur de Thèse : Dominique Mangelinck, IM2NP (Marseille)

Laboratoire d’accueil : IM2NP (Marseille) 80% + STMicroelectronics
Crolles 20%

Co-encadrant côté ST : Marc Juhel/ Magali Grégoire

Début de la thèse : Sept-Octobre 2009

Contacts : Dominique Mangelinck
Tel/Fax: [phone]
WEB: http://www.im2np.fr/
E-mail: [e-mail]

Magali Grégoire
Tel/Fax : [phone]
WEB : http://www.st.com/
E-mail : [e-mail]






M. Grégoire, M. Juhel 1/3 Description:

The increasing scaling down and complexity of microelectronics devices requires the
introduction of new materials and new processes. Moreover, reduction of dimensions
requests the development of new characterization tools and methodologies. One of advanced
characterization methods with very high spatial resolution is the tomographic atom probe
(TAP).
This instrument permits to obtain an analytical imaging of materials in three
dimensions at the atomic scale [Blavette93, Blavette99]. This technique allows
3reconstructing, atom by atom, a small piece of matter (typically 50×50×100 nm ) in the three
directions of the real space and is unique for its (a) spatial resolution in three dimensions (0.2
nm achievable), (b) analytical sensitivity (10 ppm) (c) high detection efficiency (>50%) and
(d) ability to detect all elements. Atom probe tomography uses pulsed field evaporation to
remove individual atoms (as ions) from the surface of a needle-shaped specimen. A position-
sensitive detector (Fig. 1) is used for measurement of flight time (mass-to-charge ratio) and
impact position which enables position from which each atom originates on the specimen
surface to be determined. By pilling up the images of each evaporated layer, a 3D image of
the atoms present in the volume is obtained. The depth resolution of a single atomic layer and
sub-nanometer lateral resolution is readily achieved. Atomic probe tomography has been
applied in the analysis of precipitation or thin film formation of nanometric phases as
silicides.


Fig. 1: Principle of the atom probe tomography. In the laser assisted tomographic atom
probe fs laser pulses are used in place of H.V. pulses.


One of major changes in recent technologies deals with the introduction of new
dielectric compounds for gate oxide layers. The tomographic atom probe could play a
significant role in the very challenging characterization of these new “metal gates” (Fig. 2).
For key electronics applications, a 32nm-CMOS technology based on metal gate and high-k
with gate first scheme is developed. This integration is a revolution in nanoelectronics and
this huge change was motivated by several raisons (better drivability of the transistor with
thinner gate oxide, reliability and power) [Arnaud 08].

M. Grégoire, M. Juhel 2/3 Metal TiN
Oxyde
““HHiigghh--kk””


Fig. 2: TEM cross-section of 32nm-CMOS devices based on the revolutionary metal gate
integration (gate first scheme, [Chudzik’07][Narayanan’08].

The interfaces between high-k materials (La O , HfO , Al O ) and metals in such 2 3 2 2 3
dimensions remain critical. The segregation at interfaces observed for several elements as
Nitrogen or Nitrogen diffusion inside high-k material degrade transistor performances. The
atom probe tomography could also permit to identify clearly structure and chemical
composition at a nanoscale in the complex metal gate device.

A preliminary planning for the 3 years work would be:
- An experimental work on the tomographic atom probe technique focussed on high-k
metal gate characterization. Both sample preparation, analytical parameters (such as laser
wavelength) and data processing will be addressed. This work will drive technical
improvement on spatial resolution and quantification.
- The second part of the work will be to study the thermal diffusion of high-k metal
gate materials in correlation with device performance.
- The samples will be both blanket wafers without pattern and real devices from
STCrolles 45nm and 32nm process technologies.



[Blavette93] D. Blavette, A. Bostel, J. M. Sarrau, B. Deconihout and A. Menand, Nature 363
(1993) 432-435
[Blavette99] D.Blavette, E. Cadel, A. Fraczkiewicz, A. Menand Three-dimensional atomic-
scale imaging of impurity segregation to line-defects SCIENCE Dec 17 (1999) 2317-2319
[Arnaud 08] F. Arnaud et al. VLSI2008


M. Grégoire, M. Juhel 3/3