AVS 63rd International Symposium & Exhibition
    Electronic Materials and Photonics Thursday Sessions
       Session EM+SS+TF-ThA

Paper EM+SS+TF-ThA8
Using X-ray Reflectivity to Measure the Vacuum Ultraviolet Absorption Spectrum in Low-k Dielectrics

Thursday, November 10, 2016, 4:40 pm, Room 102A

Session: Materials and Interfaces for Energy Storage
Presenter: Faraz Choudhury, University of Wisconsin-Madison
Authors: F.A. Choudhury, University of Wisconsin-Madison
H.M. Nguyen, University of Wisconsin-Madison
W. Li, University of Wisconsin-Madison
Y. Nishi, Stanford University
J.L. Shohet, University of Wisconsin-Madison
Correspondent: Click to Email
During plasma processing, low-k dielectrics are exposed to high levels of vacuum ultraviolet (VUV) radiation that can cause severe damage to the dielectric material. The degree and nature of VUV-induced damage depends on the VUV photon energies.[1] In this work, we determine the VUV absorption spectrum of low-k organosilicate glass (OSG) using specular X-ray reflectivity (XRR). Low-k SiCOH films were exposed to synchrotron VUV radiation with energies ranging from 7 to 25 eV and the electron density depth profile of the VUV irradiated films were extracted from the fitting of the XRR experimental data using the Parratt method. The results show that the depth of the VUV induced damage layer is sensitive to the photon energy. Between 7 to 11 eV, the depth of the damaged layer decreases sharply from 110 nm to 60 nm and then gradually increases to 85 nm at 21 eV. The maximum VUV absorption in low-k films occurs between 11 and 15 eV. This method is also utilized to investigate the penetration depth of 5 to 25 eV photons in porous SiCOH films with porosities ranging from 15 to 50%. It is seen that the penetration depth of photons increases with porosity. This work shows that XRR electron density depth profiling can be a very effective, non-destructive tool to determine the penetration depth and absorption coefficients of photons and other reactive species from a plasma in various kinds of dielectric films.

This work was supported by the Semiconductor Research Corporation under Contract 2012-KJ-2359

[1] T. V. Rakhimova et al, J. Phys. D: Appl. Phys. 47 (2014) 025102