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of superhydrophobic surfaces and
fluorine-free materials to preempt future
chemical restrictions.
References
1. Y. Ito, et al., “Impact of chip-
edge str uctures on alignment
accuracies of self-assembled dies for
microelectronic system integration,”
vol. 25, no. 1, p. 91-100, Feb. 2016.
2. B. Chang, et al., “Self-transport and
self-alignment of microchips using
microscopic rain,” Sci. Rep. Nat.,
2015.
3. V. Dubey, et al., ”Physics of
self-aligned assembly at room
temperature,” Phys. Fluids, vol. 30,
no. 1, Jan. 2018.
Figure 6: Super-hydrophobic surface integrated with a hydrophilic area. 4. F. Grossi, “Techniques innovantes
d’auto-assemblage, d’auto-alignement
Hydrophobic and super- Components Research have worked on the et de connectique de puces sur
hydrophobic surface fabrication integration of an alternative F-free material substrat basées sur le collage direct,”
As pa r t of i nvest igat ion s i nto to comply with future Registration, PhD work report, 2010.
se l f- a s se m b l y p ro c e s se s , s o m e Evaluation, Authorisation and Restriction 5. S. Mermoz, “Auto-assemblage
academic groups have reported on of Chemicals (REACH) restrictions [9]. assisté par capillarité et collage
the use of superhydrophobic surfaces. direct,” PhD work report, 2015.
Superhydrophobicity is defined as a WCA Summary 6. A. Jouve, et al., “Self-assembly
exceeding 120°C. At CEA-Leti, we are The capillary force of a water droplet process for 3D die-to-wafer using
also investigating these types of surfaces can be exploited to quickly align dies direct bonding: A step forward
and their integration to assess how they and produce self assembly. It could toward process automatisation,”
affect alignment capability. We have be a good option to increase both ECTC Conf., 2019.
integrated a superhydrophobic area, with throughput and alignment capabilities 7. A. Bond, et al., “Collective die-
a water contact angle of 150°C, next to a compared to direct placement D2W. In- to-wafer self-assembly for high
hydrophilic surface (WCA <15°C). Tests depth work to integrate this process alignment accuracy and high
will now be performed on the alignment has been undertaken jointly by CEA- throughput 3D integration,” ECTC
capability of this area (Figure 6). Leti and Intel Components Research, Conf., 2022.
Another topic linked to hydrophobic with results so far revealing good 8. E. Bourjot, et al., “Integration and
surfaces is the use of organofluorinated compatibility with the fabrication process challenges of self assembly
hydrocarbon compounds. This year, the of microelectronics assemblies. The applied to die-to-wafer hybrid
European Chemical Agency is debating the next steps for the development of this bonding,” ECTC Conf., 2023.
restriction of such fluorinated compounds, technology are electrical validation of 9. P. M o n t m é a t , e t a l. , “ H i g h
which are persistent substances that the assemblies, and the development cleanliness and high hydrophobic/
accumulate in the environment and in of an industrial assembly tool. To hydrophilic contrast done by direct
the human body. Those materials are c ont i nue t he ex plor at ion of t he wafer bonding for die-to-wafer
very widely used in industry for their fabrication of hydrophobic areas, CEA- self-assembly,” ECS meeting,
hydrophobic properties. CEA-Leti and Intel Leti is investigating the integration Gothenburg, Sweden, Oct. 2023.

Biographies
Emilie Bourjot is a Project Manager at CEA-Leti, Grenoble, France. Her current activities involve
developing advanced hybrid bonding schemes for 3D integration. Prior to joining CEA-Leti, she worked with
GlobalFoundries (Germany, USA) and within the IBM Alliance (USA) on the development of advanced FDSOI
technologies and sub-3nm nodes. She holds a Masters in Materials Physics from INSA Lyon, France, and a PhD
from Aix-Marseille U., France. Email emilie.bourjot@cea.fr
Frank Fournel is the head of wafer bonding technology engineering at CEA-Leti, Grenoble, France. He is
also a board member of the international ECS Wafer Bonding Symposium conference, the International Wafer Bond conference,
and the Low Temperature Bonding 3D conference. He has more than 180 international publications, 120 deposited patents. He
graduated from the “Ecole Supérieure de Physique et de Chimie Industrielle” de la ville de Paris (ESPCI) with a masters in
Materials Science, and received his PhD in 2001.

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