Atomic Layer Deposition (ALD) of high-dielectric constant materials such as, HfO2, Y2O3, TiO2

Fabrication of HfO2 & TiO2 nanotubes by ALD on electrospun polymeric templates;

Abstract

Ultrathin structures of new high-dielectric constant materials are the key of the success of the future fabrication of semiconductor devices. The use of traditional silicon dioxide as a gate dielectric insulating layer has reached its fundamental limits in terms of gate controlled mobility without excess leakage current of gate channel diffusion. These problems need to be solved by finding alternate materials, such as high-dielectric constant materials.

Hafnium oxide (k~20) has been heralded as the new high dielectric constant material for the gate dielectric layer in the future transistors and capacitive memory cells. However, further device scaling necessary for maintaining the Moore’s law would require dielectric materials with even higher permittivity. Interestingly, the cubic and tetragonal polymorphs of hafnium oxide hold promise because of their higher permittivities (k~29 and k~70, respectively) based on theoretical calculations. My goal is to achieve those high-k polymorphs states by doping yttria to the hafnia films using atomic layer deposition.

The project of fabrication of HfO2 and TIO2 nanotubes is actually a joint project with another group where the polymeric template could be made by electrospun. I’m now working on how to smooth the ALD process to achieve more uniform HfO2/TiO2 coatings on the polymeric template.