Recent Events

Field Trip: March 28th 2002

Center for Semiconductor Research at Research Triangle Park,

The tour was directed by Dr. Rama Venkatasubramanian,   
Senior Program Director

For more information: http://www.rti.org/units/es/csr.cfm    

Pictures Related to this Event:       

Click on the pictures to enlarge.

MRS Chapter Meeting:

The following talks were given in the meeting

"Chemical, Electrical and Structural Properties of Au/Pd Contacts on Chemical Vapor Cleaned p-type GaN Surfaces" by Phil Hartlieb

"Electrical Activity at Interfaces, Z-contrast Imaging" by Gerd Duscher

We would like to thank the Chemistry Department of NC State for providing drinks and pizza for this event

 April 18, 2002: MRS Student Chapter Meeting

"Mechanical and Electrical Properties of Nanocrystalline and Epitaxial TiN Films:" 

By Haiyan Wang
Materials Science and Engineering Dept.
Department of Materials Science and Engineering,
North Carolina State University, Raleigh, North Carolina 27695-7916

ABSTRACT: 

High-temperature materials such as TiN have been successfully applied as wear corrosion protection, decorative coatings, electrical contacts and diffusion barriers in electronic devices. However the poor toughness and ductility have limited some of these applications. To alleviate some of these problems, reduction of grain size can enhance grain boundary sliding and grain boundary diffusion related creep phenomena. We have investigated mechanical and electrical properties of TiN as a function of microstructure varying from nanocrystalline to single crystal TiN films deposited on (100) silicon substrates. By varying the substrate temperature from 25^oC to 700^oC during pulsed laser deposition, the microstructure of TiN films changed from nanocrystalline (having uniform grain size of 8 nm) to a single crystal epitaxial film on the silicon (100) substrate. The microstructure and epitaxial nature of these films were investigated using X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). Hardness measurements were made using nanoindentation techniques. Resistivity measurements were performed by van der Pauw method. The hardness of TiN films decreased with decreasing grain size in nanoscale. This behavior has been modeled recently involving grain boundary sliding which is particularly relevant in the case of hard materials such as TiN. The dependence of resistivity of TiN as a function of the deposition temperature is discussed. TaN, a new generation diffusion barrier material for Cu interconnections, can be grown on Si(100) and Si(111) substrate epitaxially using  single crystal TiN buffer layer. It is the first time to report the single crystal cubic TaN growth on Si substrate.

Awards: MRS 2001 fall meeting graduate student award silver metal winner.

Student member: MRS, ASM, TMS, APS.