In-situ Transmission Electron Microscopy Studies of Metal Contact with InGaAs Nanochannels: Correlating Interface Reactions with Properties

University Of California-San Diego, La Jolla CA

Investigators

Abstract

Non-Technical Description: This research project focuses on the development of fundamental understanding and control of metal-semiconductor reactions at nanoscale. The research team utilizes transmission electron microscopy (TEM) to study, at the atomic scale and in real time, the relationship between structure, properties, and functionality of these nanoscale materials similar to the working conditions of a new class of nanoscale transistors. The research is expected to provide new insights into the fundamental materials science on the metal-semiconductor interface and their reactions, an area of technological importance for developing metal contacts for advanced III-V compound semiconductor transistor channels. The outreach and educational activities are well integrated with the research activities and include (1) developing new sections in current graduate and undergraduate courses in the multidisciplinary area of semiconductor heterostructures and microfabrication, and (2) involving high-school and undergraduate students in hands-on research through various outreach activities at UC San Diego, with a particular emphasis on the inclusion of underrepresented groups. Technical Description: In this research project, the PI and his team utilize a novel transmission electron microscopy (TEM) measurement method to monitor, in-situ, reactions of metal contact with III-V semiconductors. Fins of III-V semiconductors are wafer bonded to a Si TEM grid using Ni silicidation to form free-standing nanoscale heterostructures (i.e., nanochannels) for both in-situ heating study and ex-situ electrical measurements. Multiple nanochannels designed with various channel widths, III-V crystallographic orientations, and surface morphologies, can be integrated on the same TEM grid for the combined in-situ and ex-situ studies. With this capability, the team correlates the resulted nanochannel composition, interface structure and the transistor performance with the effects of III-V fin size, crystallographic orientation and stress. In particular, the research work allows experiments on alloy formation between Ni and InGaAs as a function of size and crystal orientation and addresses the following scientific questions: (i) the III-V fin size effects on the structure and composition of the formed NiInGaAs alloys, (ii) the influence of interfaces and strain engineering on the Ni-InGaAs reaction and nucleation in ultra-short channels, and (iii) the effect of a limited Ni diffusion source in a multi-layered contact stack on the alloy composition and structure. The findings are important for developing Ohmic contacts for sub-10 nanometer III-V compound semiconductor transistor channels. The wafer bonding of nanochannel structures on TEM grid for the combined in-situ TEM and ex-situ electrical study can potentially enable fundamental interface studies in other materials systems.