Characteristics of HfO2 and SiO2 on p-type silicon wafers using terahertz spectroscopy

Altan H., Sengupta A., Pham D., Grebel H., Federici J. F.

SEMICONDUCTOR SCIENCE AND TECHNOLOGY, vol.22, no.5, pp.457-463, 2007 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 22 Issue: 5
  • Publication Date: 2007
  • Doi Number: 10.1088/0268-1242/22/5/001
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.457-463
  • Middle East Technical University Affiliated: Yes


The effect of high-kappa dielectric HfO2 films on 200 mm diameter p-type silicon substrates was investigated and compared with conventional dielectric material, SiO2. We employed all-optical characterization methods using terahertz (THz) time-domain spectroscopy and visible cw pump/THz probe spectroscopy. Measurements were performed on two sets of samples, each set containing both HfO2 and SiO2 coated wafers with varying thickness of oxide layer. One set had a protective coating of either photoresist or Si3N4 deposition above the oxide layer which in turn was on a heavily doped p+ layer on p-type silicon. The samples exhibited similar linear transmission in the THz frequency range studied. However, when using an Ar+-ion laser as an optical pump source, differential measurements (with and without the pump source) showed that the transmission was far smaller for the high-kappa dielectric HfO2 films than its conventional dielectric SiO2 counterparts, indicating the presence of large photo-generated carrier density in the p-type substrate.