In situ TEM Study of Ni-InGaAs Solid-State Reactions

In situ TEM Study of Ni-InGaAs Solid-State Reactions

Renjie Chen

• 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.

[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

Introduction

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• 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.

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Content

1. Introduction

• Ni – III-V solid state reaction• In-situ TEM & Our group’s work

2. My Preliminary results

• Process design to fabricate channels on TEM membrane• Recipe modification

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Self-aligned S/D Contact Technology

Kim, S. etc. Electron Devices Meeting (IEDM), pp 26.6. 1-26.6. 4

Ivana; Pan, J. etc. Applied Physics Letters 2011, 99 (1), 012105-3

Subramanian, S.; etc. Journal of The Electrochemical Society 2011, 159 (1), H16-H21

Ni-InGaAs Solid-State Reaction

Crystallographic Study of Ni-GaAs

Lahav, A.; Eizenberg, M.; Komem, Y., Interfacial reactions between Ni films and GaAs. Journal of Applied Physics 1986, 60 (3), 991-1001.

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)

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Ni-InAs in Nanoscale Channels

Chueh, Y.-L., et al. (2008). "Formation and Characterization of NixInAs/InAs Nanowire Heterostructures by Solid Source Reaction." Nano Letters 8(12): 4528-4533

Diffusion Modal with Constant Source:

Diffusion length: X = (Dt)1/2

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In-situ TEM Technique

MRS BULLETIN • VOLUME 33 • FEBRUARY 2008 • www.mrs.org/bulletin

Frances M Ross 2010 Rep. Prog. Phys. 73 114501

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Previous Work in Our Group

Heterogeneous Reactions in Ge/Si Core/Shell Nanowires

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

Dr. Minh’s work, submitted

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Heterogeneous Reactions with presence of TB:

Heterogeneous Reactions with presence of TB and GB:

Nucleation Modeling:

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

Ni

InGaAs[110]

Ni

TEM membrane

Ni

InGaAs[100]

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

Remove InP• 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)

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Approach 2: Ni-InGaAs Bonding

• 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)

Bonding with Ni-InGaAs

InP Removal

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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 9 windows (100um x 100um)

TEM aperture with multiple windows increases the chance for unbroken window:

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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:

MF 319Low T developing process

25% HDMSHigh T developing process

Without surrounding Ni lines With surrounding Ni lines Dense Ni lines

Summary

• In situ TEM observation is powerful to investigate the Ni-InGaAs solid state reaction .

• Diffusion rate, alloy frontier interface, and crystallographic relationship can be studied during in situ TEM observation.

• Currently, the InGaAs membrane was successfully transferred with modified bonding process, and several problems associated with EBL writing has been solved.

• 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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