University of Tokyo first to demo III-V self-aligned source/drain

by Laura Peters, contributing editor

IEDM Previews:
Intel fabs highest mobility pFET with Ge channel
University of Tokyo first to demo III-V self-aligned source/drain
IBM, Macronix identify phase-change memory failure mode
Record photodiode quantum efficiency from Taiwan lab
How strain can protect devices from ESD
SEMATECH tipping III-V MOSFET, FinFET, and resistive RAM
TSMC anneal for gate-last HKMG process
Imec IEDM presentations to cover More than Moore, ITRS
When do TSV stresses affect device operation?
Multi-threshold-voltage flexibility in FDSOI
CMOS imager works from light to night
Carbon nanotube vias approach production densities
IBM Alliance simplifies pFET HKMG
IM Flash details 25nm NAND

November 23, 2010 - Deeply scaled MOSFETs require a self-aligned source/drain (S/D) manufacturing strategy. For the upcoming III-V semiconductors with high-mobility channels, low-resistance contact with self-aligned S/D is essential, but has not been successfully demonstrated. However, at the upcoming International Electron Devices Meeting (IEDM, 12/6-8 in San Francisco, CA), researchers from the University of Tokyo, the National Institute of Advanced Industrial Science and Technology (AIST, Ibaraki, Japan) and Sumitomo Chemical Co. (Ibaraki), will present promising results on the fabrication of a Ni-InGaAs alloy, formed by direct reaction of nickel and InGaAs, to yield low-resistance, self-aligned S/D InGaAs MOSFETs for the first time.

A major challenge the researchers faced is the low electron Schottky barrier height (SBH) with InGaAs. In their studies of the I-V characteristics of n-type and p-type InGaAs diodes, among the metals Ni, Ti, Sn and Al, nickel provided the highest current in the n-InGaAs contact and good rectifying behavior with an on/off ratio of 105 in the p-InGaAs contact. Also, a 1-min 250°C anneal is sufficient to provide a uniform Ni-InGaAs alloy layer.

The Schottky barrier height was determined to be 83-120meV. To lower this further, the team fabricated Ni-InGaAs/InxGa1-xAs Schottky diodes with varying concentrations of indium (x=0.4, 0.53, 0.6, 0.7, 0.8). The indium layers, with a thickness of 500nm, were grown on InP substrate by metalorganic vapor phase epitaxy. The nickel was deposited by evaporation. The I-V characteristics (Figure 1) showed an enhancement of the reverse current with increasing indium content, but the rectifying behavior was weakened because of the bandgap lowering. The Schottky barrier height was zero for indium content of 0.7 and 0.8 (Figure 2). Sheet resistance was low and constant with indium content.

Figure 1: I-V characteristics of Ni-InGaAs alloy/n- InxGa1-xAs and Ni-InGaAs/p- InxGa1-xAs diodes with x=0.4, 0.53, 0.6, 0.7, 0.8.

With favorable electrical results, the team went on to fabricate In0.7Ga0.3As MOSFETs.

With higher indium content came simultaneous increases in drive current and lowering of S/D resistance. The lower Schottky barrier height and low sheet resistance of Ni-InGaAs alloy delivers reduced S/D resistance in InGaAs MOSFETs with high electron mobility.

Figure 2: Increasing indium content brings down the Schottky barrier height of the as-deposited diode and Ni-InGaAs/ InxGa1-xAs after RTA.


Easily post a comment below using your Linkedin, Twitter, Google or Facebook account. Comments won't automatically be posted to your social media accounts unless you select to share.

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>



Edwards launches new vacuum pumps at SEMICON China 2016
03/15/2016Edwards announced the availability of two new vacuum pump product families at SEMICON China: the iXM Series for semiconductor etch and chemical v...
Low-outgassing Faraday Isolators to improve lifetime and reliability of optical systems
02/18/2016Qioptiq, an Excelitas Technologies company introduces the LINOS Low-outgassing Faraday Isolators, the first of th...
Versatile high throughput SEM from JEOL
11/04/2015JEOL's new JSM-IT100 is the latest addition to its InTouchScope Series of Scanning Electron Microscopes....