Investigation on hexamethyldisilazane vapor treatment of plasma-damaged nanoporous organosilicate films T. Rajagopalan a , B. Lahlouh a , J.A. Lubguban b , N. Biswas a , S. Gangopadhyay b, * , J. Sun c , D.H. Huang c , S.L. Simon c , D. Toma d , R. Butler d a Department of Physics, Texas Tech University, Lubbock, TX 79409, USA b Department of Electrical and Computer Engineering, University of Missouri, Columbia, MO 65211, USA c Department of Chemical Engineering, Texas Tech University, Lubbock, TX 79409, USA d TEL, Austin, TX, USA Received 2 June 2005; accepted 22 August 2005 Available online 27 September 2005 Abstract Hexamethyldisilazane (HMDS) vapor treatment of plasma-damaged nanoporous organosilicate thin films has been studied as a function of treatment temperature in this work. Although, the HMDS vapor treatment facilitated incorporation of methyl (CH 3 ) groups subsequent to the removal of free hydroxyl (OH) groups in the damaged films at treatment temperature as low as 55 8C, the bonded OH groups were not removed. More significantly, detailed analysis of the results reveals that HMDS vapor modified only the surface of the plasma-damaged samples and not the entire film as expected. This is attributed to the formation of a thin solid layer on the surface, which effectively prevents penetration of HMDS vapors into the bulk. The Fourier transform- infrared (FT-IR) absorption and dielectric constant measurements confirm that the vapor treatment assists only partial curing of the plasma-damaged films. Alternative processes of curing the films with HMDS dissolved in supercritical carbon dioxide (SCCO 2 ) as a medium of reaction in static and pulsed modes were also attempted and the results are presented in this paper. # 2005 Elsevier B.V. All rights reserved. Keywords: Plasma-damage; Porous films; Low-k; Supercritical CO 2 1. Introduction High on-chip speeds require the use of low dielectric constant (k) materials for insulation. Low- ering the k-value reduces the cross-talk noise and minimizes the dissipated power in the circuit by lowering the resistance–capacitance (RC) constant of the device [1–3]. Many research groups are involved in the development of a suitable low-k material. A wide range of spin-on and plasma enhanced chemical vapor deposited films are being explored as potential www.elsevier.com/locate/apsusc Applied Surface Science 252 (2006) 6323–6331 * Corresponding author. E-mail address: gangopadhyays@missouri.edu (S. Gangopadhyay). 0169-4332/$ – see front matter # 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.apsusc.2005.08.060