Epitaxial growth of NiSi 2 induced by sulfur segregationat the NiSi 2 /Si(100) interface

  • PDF / 1,193,731 Bytes
  • 5 Pages / 584.957 x 782.986 pts Page_size
  • 52 Downloads / 285 Views

DOWNLOAD

REPORT


S.B. Mi and C.L. Jia Institute of Solid-State Research, Forschungszentrum Ju¨lich GmbH, 52425 Ju¨lich, Germany

C. Urban, C. Sandow, S. Habicht, and S. Mantl Institute of Bio- and Nanosystems (IBN1-IT), and Center of Nanoelectronic Systems for Information Technology (CNI), Forschungszentrum Ju¨lich GmbH, 52425 Ju¨lich, Germany (Received 30 May 2008; accepted 23 September 2008)

Epitaxial growth of a NiSi2 layer was observed on Sþ ion-implanted Si(100) at a low temperature of 550  C. Depending on the Sþ dose and the Ni thickness, we identified different nickel silicide phases. High quality and uniform epitaxial NiSi2 layers formed at temperatures above 700  C with a 20-nm Ni on high dose Sþ implanted Si(100), whereas no epitaxy was observed for a 36-nm Ni layer. We assume that the presence of sulfur at the silicide/Si(100) interface favors the nucleation of the NiSi2 phase. The S atom distributions showed ultrasteep S depth profiles (3 nm/decade) in the silicon, which results from the snow-plow effect during silicidation and the segregation of S to the interface due to the low solubility of S in both Si and the silicide.

I. INTRODUCTION

As the dimensions of metal-oxide-semiconductor field-effect transistors (MOSFET) are scaled below 32 nm, the source and drain contacts determine greatly the parasitic series resistance. Replacing the conventional highly doped source/drain (S/D) contacts by metallic Schottky junctions holds great potential for nanometer scale devices because of several advantages: lower parasitic S/D resistance, abrupt junctions, reduced capacitive coupling, and device processing at much lower temperatures. However, Schottky barrier (SB) transistors manufactured with conventional silicides suffer on too low on-currents because of the limitation of the tunneling current through the SB. S/D junctions with an ultralow or an even negative SB height (SBH) would increase the on-current substantially. Recently, we developed a method to tune the SBH of NiSi on Si(100) by using sulfur ion implantation and silicidation induced S segregation.1,2 Sþ ions were implanted into the Si(100) substrate before the Ni deposition. During the following silicidation at temperatures around 500  C the whole Sþ implanted Si region was consumed, and segregation of S at the NiSi/Si(100) interface occurred a)

Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/JMR.2009.0006 J. Mater. Res., Vol. 24, No. 1, Jan 2009

http://journals.cambridge.org

Downloaded: 14 Mar 2015

due to the snow-plow effect. As a result, the SBH of NiSi decreased on n-Si(100) and increased correspondingly on p-Si(100).1 By lowering the SBH of the silicide S/D to the channel interfaces, the performance of the SB transistor could be improved reflected by higher on-currents and lower off-currents.2 Silicide films with atomically flat silicide/Si interfaces are particularly beneficial for nanoscaled devices. Such silicide/Si contacts can be realized with epitaxial silicides, which have superior properties because of the exce

Data Loading...