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), th International Workshop on, IEEE: 2011; pp 1-6 Introduction 2/26 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.

3/26 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

4/26 Self-aligned S/D Contact Technology Kim, S. etc. Electron Devices Meeting (IEDM), pp Ivana; Pan, J. etc. Applied Physics Letters 2011, 99 (1), 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), GaAs Zinc Blende (a = Å) Ni 2 GaAs hexagonal (a = 3.83 Å, c = 5.04 Å) NiAs hexagonal (a = Å, c = Å) β-NiGa cesium chloride (a = Å) 5/26

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): Diffusion Modal with Constant Source: Diffusion length: X = (Dt) 1/2 6/26

7/26 In-situ TEM Technique MRS BULLETIN VOLUME 33 FEBRUARY Frances M Ross 2010 Rep. Prog. Phys

8/26 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), Dr. Minh’s work, submitted

9/26 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),

10/26 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

11/26 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)

12/26 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

13/26 Approach 1: Ni-silicide BondingApproach 2: Ni-InGaAs Bonding Decrease Ni film thickness TEM aperture with 1 window (500um x 500um)

14/26 TEM aperture with 9 windows (100um x 100um) TEM aperture with multiple windows increases the chance for unbroken window:

15/26 Fabricate InGaAs Diffusion Channels on Membrane Window 1 st EBL step: Write global/chip marks, followed by evaporation of Ni/Au/Ni 2 nd EBL step: Write Parallel lines on each window, evaporate Ni as both the reaction reservoir and the supporting lines 2 nd EBL step: Write Fin structure in between the Ni lines with different orientation

16/26 MMA/PMMA double layers improve the lift-off process:

17/26 Modified HSQ recipe for Fin writing: MF 319 Low T developing process 25% HDMS High 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. 18/26

Thanks Q&A 19/26