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Daniel Josell (Fed)

Dr. Daniel Josell joined NIST as a National Research Council postdoctoral researcher in the Metallurgy Division of the Materials Science and Engineering Laboratory in 1992. He became a permanent staff member in 1994. He has been Deputy Chief of the Metallurgy Division of NIST's Materials Science and Engineering Laboratory as well as Leader of the Division's Thin Film and Nanostructure Processing Group. He has also been a Technology Analyst in NIST's Program Office. He is author of more than 140 technical papers and book chapters and five US patents.

He has received the:

  • Federal Laboratory Consortium Award for Excellence in Technology Transfer (1999) 
  • Gold Medal Award of the U.S. Department of Commerce (2001)
  • Samuel Wesley Stratton Award of the National Institute of Standards and Technology (2011)
  • Electrodeposition Division Research Award of The Electrochemical Society (2020)
  • Excellence in Technology Transfer Award of the National Institute of Standards and Technology (2023)

Over the last decade his research has focused on advanced electrochemical deposition processes for void-free, defect-free filling of recessed features, including for fabrication of interconnects for microelectronics and gratings for X-ray phase contrast imaging:

  • Detailed theoretical and experimental study of superconformal deposition of metals in trenches and vias ranging from tens of nanometer to nearly a millimeter in depth
  • Explained superconformal electrodeposition and superconformal surfactant catalyzed chemical vapor deposition of copper
  • Achieved and quantified superconformal silver and gold electrodeposition
  • Demonstrated seedless processing for copper superfill
  • Developed bottom-up gold filling of high aspect ratio trenches in X-ray Phase Contrast Imaging (XPCI) diffraction gratings for soft tissue imaging

He has also examined the mechanical and thermal transport properties of multilayered materials, the thermodynamics of interfaces and the stability of nanoscale materials and structures. 

  • Creep and tensile testing of multilayer thin films including study of capillary influences that affect their stability
  • Experimental and computational studies of solder joint geometries
  • Pyrometry and polarimetry studies of the rapid melting of refractory alloys
  • Determination of thermal transport properties of thin film and multilayer coatings at room and elevated temperatures

Results for some efforts are given below (full details can be found in the publications).

Superfill for interconnect fabrication: Superconformal deposition has enabled damascene copper interconnects in microelectronics. Models based on the Curvature Enhanced Accelerator Coverage (CEAC) mechanism capture all aspects of superfill: incubation period of conformal growth, accelerating bottom-up filling, and overfill bump formation

CEAC filling derivatived
Experiment and prediction of copper superfill in trenches

CEAC-derived superconformal deposition is generic, as shown by silver superfill.

Silver superfill
Silver superfill evolution

 

 

 

 

 

 

 

Filling of larger features by S-NDR mechanism: Electrolytes that allow passivation of a portion of the surface while another portion is actively depositing can yield bottom-up deposition in patterned features. The mechanism underlies copper filling of Through Silicon Vias (TSV) for wafer stacking applications in microelectronics. S-NDR models explain this phenomenon, having provided quantitative prediction of copper, nickel, cobalt and gold feature filling, including two quite different geometries from the same mechanism:

S-NDR two geometries
Predicted superconformal filling geometries and demonstrations with nickel (top) and copper (bottom) derived from suppressed-electrolytes through S-NDR mechanism

S-NDR models predict bottom-up Cu deposition in micrometer size TSV

Cu fill map
Processing map for bottom-up superconformal copper filling of annular through silicon vias (TSV) through S-NDR mechanism

as well as much larger, millimeter size vias

mm-TSV bottom-up fill
Superconformal copper filling of millimeter-size vias in electrolyte through S-NDR mechanism

and Through-Hole vias for printed circuit boards

Through hole simulations
Simulations of S-NDR derived superconformal copper filling of through vias with "butterfly" evolution

The models also explain activation of the feature bottom as well as a portion of the sidewalls observed with systems exhibiting substantial suppressor incorporation, including cobalt

Cobalt S-NDR fill
Localized and superconformal cobalt deposition in annular TSVs through S-NDR mechanism.

Bottom-up gold deposition for diffraction gratings: A newly developed process yields void-free, defect-free bottom-up gold deposition in tall and high aspect ratio features. In its third year, the effort received support from NIST's Associate Director for Laboratory Program through the Technology Maturation Accelerator Program. Collaborations focus on transferring NIST's Au filling technology for fabrication of diffraction gratings used in imaging applications.

Bottom-up gold
Bottom-up gold filling of damascene size trenches

Filling of taller features requires a shift to more positive potentials that yield an increasingly long period of passive deposition prior to bottom-up filling.

Bottom-up gold incubation
Bottom-up gold filling  of trenches having intermediate aspect ratios

The process can be made self-passivating, filling automatically halting at a controllable distance from the field.Void-free filling of trenches up to 210 micrometers deep and with aspect ratio (height/width) up to 30 has been detailed.

bottom-up fill 45 micron
Bottom-up gold filling in trenches of intermediate depth and aspect ratio. The microstructure results mainly from recrystallization originating at the sidewalls.
Josell Au fill
Microstructure of gold fill in 21 micrometer wide, 300 micrometer deep trench manifests bottom-up filling in central region
Credit: Josell

 

Void free, bottom-up gold filling has been demonstrated in trenches of aspect ratio 60 on fully patterned 100 mm diameter silicon wafers, the deposition system shown below. This includes fabrication of the "gratings" of parallel trenches on the wafers shown below as well as arrays of vias and fractal patterns.

Au fill deposition system
Bottom-up gold filling of gratings at the wafer scale.

The below images of gold filled gratings whose trenches are approximately 60 times taller than their 1 micrometer width exhibit flat fill on the upper profiles that captures not only the self-passivation of the process but also makes clear the ability to fill even higher aspect ratio features.

Gold filled grating AR 60
Bottom-up gold filling of high aspect ratio trenches in a grating.

The gold filled gratings are used in X-ray Phase Contrast Imaging (XPCI) systems that provide high contrast, high resolution images of soft tissue rather than just imaging of bones in conventional X-ray absorption imaging. Inexpensive XPCI systems can thus provide general medical imaging in place of expensive MRI systems (with associated need for increasingly expensive helium) or CT scans that require injection of gadolinium dyes into the patient.

Mouse Heart XPCI imaged
A mouse heart as viewed by phase contrast imaging using bottom-up gold filled gratings

3D microstructured photovoltaics: Photovoltaic devices with interdigitated back contacts are fabricated using a single lithography step followed by (non)selective deposition of p-type and n-type materials.

3D CdSe-CdTe
A CdTe-CdSe dual back-contact solar cell.

Optical response of structures with systematically varied geometries (e.g., electrode height, width and pitch) can be used to characterize the properties of materials and interfaces in structured photovoltaic devices.

Map of response
Local assessment of the dual back-contact photocell efficiency.

The role of surface passivation in eliminating defects that reduce define performance is also examined, using both standard i-V response under illumination as well as spatial mapping.

Map of response with passivation
Dual back-contact solar cell operating performance, macroscopic and local assessment.

Exploding wire experiments and modeling - studies of alloy melting: Surface morphology of rapidly melted TiNb alloys near critical features of the melting plateau reflect solidus and liquid temperatures that are measured through combination of pyrometry and polarimetry.

Surface morphology capturing TiNb alloy melting localized to grain boundaries as well as within the bulk of grains.

The impact of grain size on local melting rate, and thus solute diffusion, is captured in rescaled data.

Liquidus and solidus temperatures
Assessment of alloy melting

 

 

 

 

 

 

 

Thermal transport in multilayered films: Measurements using the "Mirage" technique enable measurement of thermal transport both in-plane and normal to the surface of thin film samples. These results showed the impact of decreasing the nanometer-scale bilayer thickness in Ti/Al multilayers of total thickness 3 micrometers.

Geometry of mirage-technique measurement system
Thermal transport normal to Ti and Al layering
Thermal transport parallel to Ti and Al layering

 

 

 

 

 

 

Interpretation of these and other properties of multilayer thin films must necessarily consider their microstructure, including interfacial mixing as evident in TEM images and associated composition maps of some of the Ti/Al multilayers.

Atomic scale imaging of Ti-Al layering
Atomic resolution image of multilayer material
Ti and Al layering in material

 

 

Awards

  • Federal Laboratory Consortium Award for Excellence in Technology Transfer (1999) 
  • Gold Medal Award of the U.S. Department of Commerce (2001)
  • Samuel Wesley Stratton Award of the National Institute of Standards and Technology (2011)
  • Electrodeposition Division Research Award of The Electrochemical Society (2020)
  • Excellence in Technology Transfer Award of the National Institute of Standards and Technology (2023)

Selected Publications

Publications

Bottom-up Au Filling of Trenches in Curved Wafers

Author(s)
Daniel Josell, Thomas P. Moffat, Thomas Gnaupel-Herold, David Raciti, Martin Stauber, Yu Q, Liyang Chen, M Rawlik, Marco Stampanoni, Lucia Romano
A 〖Bi〗^(3+)-stimulated Au electrodeposition process in slightly alkaline 〖Na〗_3 Au(〖SO〗_3 )_2+〖Na〗_2 〖SO〗_3 electrolytes has been previously demonstrated for

Implementation of a dual-phase grating 1 interferometer for multi-scale characterization of 2 building materials by tunable dark-field imaging

Author(s)
Daniel Josell, Caori Organista, Ruizhi Tang, Zhitian Shi, Konstantins Jefimovs, Lucia Romano, Simon Splindler, Pierre Kibleur, Benjamin Blykers, Marco Stampanoni, Matthieu Boone
The multi-scale characterization of building materials is necessary to understand macroscale mechanical processes, with the goal of developing new, better

Emission Ghost Imaging: reconstruction with data augmentation

Author(s)
Kevin J. Coakley, Heather H. Chen-Mayer, Bruce D. Ravel, Daniel Josell, Nikolai Klimov, Sarah Robinson, Daniel S. Hussey
Ghost Imaging enables 2D reconstruction of an object even though particles transmitted or emitted by the object of interest are detected with a single pixel

Patents (2018-Present)

Curved Metallic Grating And Process For Making Same

NIST Inventors
Daniel Josell and Thomas P. Moffat
Making a curved metallic grating for matching angular divergence of incident radiation includes: providing a mandrel with a curved receiving surface; disposing a planar substrate on the curved receiving surface; applying a clamping force to the planar substrate at the planar field surface; bending

Process for Making a Metallic Grating

NIST Inventors
Daniel Josell and Thomas P. Moffat
A metallic grating is formed to include a substrate; a plurality of high aspect ratio trenches disposed in the substrate such that the high aspect ratio trenches are spaced apart from one another by a field surface of the substrate; a metallic superconformal filling formed and disposed in the high

Metallic Grating

NIST Inventors
Daniel Josell and Thomas P. Moffat
A metallic grating includes a substrate; a plurality of high aspect ratio trenches disposed in the substrate such that the high aspect ratio trenches are spaced apart from one another by a field surface of the substrate; a metallic superconformal filling formed and disposed in the high aspect ratio
Created October 9, 2019, Updated February 8, 2024