Status and Prospects For VUV Ellipsometry (Applied to High K and Low K Materials)

Abstract

The recent commercialization of Vacuum Ultraviolet spectroscopic ellipsometry (VUV SE) instruments means that it is now possible to routinely perform SE measurements at wavelengths below 190 nm. This new capability has obvious implications for lithographic work but also for the characterization of other materials of importance to the Si industry. These are materials that are nominally transparent at long wavelengths but that possess unique absorption signatures in the VUV, such as newly emerging high-k gate materials (e.g. Al 2 O 3 , HfO 2 , ZrO 2 , Y 2 O 3 ) and low k materials (porous SiO 2 , organo-silicate glasses), as well as more familiar dielectrics (e.g. SiO x N y , Si 3 N 4 , SiOF, and TEOS). We provide a review of recent progress and a critical assessment of the capabilities of VUV SE with respect to a selected examples of these materials, with special emphasis on low k and high k materials. These capabilities include increased access to unique VUV spectral features as a means of tuning process parameters and increased ability to determine the thickness of thin films grown on Si. We also address the initial challenges that had to be overcome in order to develop optical constants at short wavelengths and to enable this sort of materials characterization.

Optical vs electronic gap of hafnia by ab initio Bethe-Salpeter equation

“…On the one hand, both X-ray (XPS) and ultraviolet (UPS) photoemission spectroscopy (PES), and inverse photoemission (IPS) have been used to study the electronic structure. 10,11 On the other hand, X-ray or optical absorption, 12,13 spectroscopic ellipsometry (SE), [7][8][9][14][15][16] and electron energyloss spectroscopy (EELS) [17][18][19][20][21][22] have been used to study the optical and dielectric properties. By using linearization and extrapolation techniques over measured speca) Electronic mail: benoit.sklenard@cea.fr tra, these experiments extracted gap values ranging from 5.1 13 to 5.95 eV 16 .…”