Download In situ TEM Study of Ni-InGaAs Solid

In situ TEM Study of Ni-InGaAs
Solid-State Reactions
Renjie Chen
Introduction
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As conventional Si CMOS scaling
approaches the end of the roadmap, III-V
based MOSFETs are seriously being
considered as an alternative technology to
continue Moore’s law.[1]
•
To
realized
high-performance
III-V
MOSFETs, reliable contact metals for S/D
with low contact resistance is essential,
especially in highly scales devices.
•
An atomic level understanding of the metal-semiconductor solid-state reaction can
can shed light on material-electronic property interactions at nano-scale, especially
when the intentional or unintentional defects are present.
[1] Takagi, S.; Takenaka, M. In High mobility material channel CMOS technologies based on heterogeneous integration, Junction
Technology (IWJT), 2011 11th International Workshop on, IEEE: 2011; pp 1-6
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Content
1. Introduction
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Ni – III-V solid state reaction
In-situ TEM & Our group’s work
2. My Preliminary results
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Process design to fabricate channels on TEM membrane
Recipe modification
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Ni-InGaAs Solid-State Reaction
Self-aligned S/D Contact Technology
Ivana; Pan, J. etc. Applied Physics Letters 2011, 99 (1), 012105-3
Kim, S. etc. Electron Devices Meeting (IEDM), pp 26.6. 1-26.6. 4
Subramanian, S.; etc. Journal of The Electrochemical Society
2011, 159 (1), H16-H21
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Crystallographic Study of Ni-GaAs
GaAs Zinc Blende (a = 5.654 Å)
Ni2GaAs hexagonal (a = 3.83 Å, c = 5.04 Å)
NiAs hexagonal (a = 3.602 Å, c = 5.009 Å)
β-NiGa cesium chloride (a = 2.887 Å)
Lahav, A.; Eizenberg, M.; Komem, Y., Interfacial reactions between Ni films and GaAs. Journal of Applied Physics 1986, 60 (3), 991-1001.
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Ni-InAs in Nanoscale Channels
Diffusion Modal with Constant Source:
Diffusion length: X = (Dt)1/2
Chueh, Y.-L., et al. (2008). "Formation and Characterization of NixInAs/InAs Nanowire Heterostructures by Solid Source Reaction." Nano Letters
8(12): 4528-4533
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In-situ TEM Technique
Frances M Ross 2010 Rep. Prog. Phys. 73 114501
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MRS BULLETIN • VOLUME 33 • FEBRUARY 2008 • www.mrs.org/bulletin
Previous Work in Our Group
Heterogeneous Reactions in Si Nanowires
Tang, W.; Dayeh, S. A.; Picraux, S. T.; Huang, J. Y.; Tu, K.-N., Ultrashort Channel Silicon Nanowire Transistors with Nickel Silicide
Source/Drain Contacts. Nano Letters 2012, 12 (8), 3979-3985
Heterogeneous Reactions in Ge/Si Core/Shell Nanowires
Dr. Minh’s work, submitted
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Heterogeneous Reactions with presence of TB:
Nucleation Modeling:
Heterogeneous Reactions with presence of TB and GB:
r µe
- DG* /kT
Tang, W.; Picraux, S. T.; Huang, J. Y.; Gusak, A. M.; Tu, K.-N.; Dayeh, S. A., Nucleation and Atomic Layer Reaction in
Nickel Silicide for Defect-Engineered Si Nanochannels. Nano Letters 2013, 13 (6), 2748-2753
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Transfer InGaAs Membrane onto TEM Aperture
TEM membrane
TEM membrane
InGaAs
[100]
InGaAs
[110]
Ni
Ni
Ni
Ni
Standard cubic stereographic projections
for the [001] oriented crystal
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Approach 1: Ni-silicide Bonding
Multiple Dielectric layers
Deposition
Bonding with Si
TEM aperture
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HfO2 is used for HF resist layer (10 nm)
Al2O3 acts as block layer for F-etch (6 nm)
SiO2 prevents electronic leakage (200 nm)
Ni is used for Nickel Silicide bonding (Ti 25 nm, Ni 100 nm)
Remove InP
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Approach 2: Ni-InGaAs Bonding
Bonding with Ni-InGaAs
InP Removal
• No need to remove SiNx layer
• The broken window provides natural hollow square for Ni film evaporation
• Ni for Ni-InGaAs bonding (Ti 5 nm, Ni 20 nm)
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Approach 1: Ni-silicide Bonding
Approach 2: Ni-InGaAs Bonding
Decrease Ni film thickness
TEM aperture with 1 window (500um x 500um)
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TEM aperture with multiple windows increases the chance for unbroken window:
TEM aperture with 9 windows (100um x 100um)
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Fabricate InGaAs Diffusion Channels on Membrane Window
1st EBL step: Write global/chip marks, followed by evaporation of Ni/Au/Ni
2nd EBL step: Write Parallel lines on each window, evaporate Ni as both the reaction reservoir and
the supporting lines
2nd EBL step: Write Fin structure in between the Ni lines with different orientation
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MMA/PMMA double layers improve the lift-off process:
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Modified HSQ recipe for Fin writing:
Without surrounding Ni lines
With surrounding Ni lines
Dense Ni lines
MF 319
Low T developing process
25% HDMS
High T developing process
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Summary
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In situ TEM observation is powerful to investigate the Ni-InGaAs solid state
reaction .
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Diffusion rate, alloy frontier interface, and crystallographic relationship can be
studied during in situ TEM observation.
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Currently, the InGaAs membrane was successfully transferred with modified
bonding process, and several problems associated with EBL writing has been
solved.
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Further experiments need to be done in order to prepare the sample ready for
TEM study.
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Thanks
Q&A
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