| AVS 63rd International Symposium & Exhibition | |
| Thin Film | Monday Sessions |
| Session TF+PS+SE-MoA |
| Session: | Plasma-based Deposition Techniques and Film Characterization |
| Presenter: | Ségolène Liénard, Univ. Grenoble Alpes, LTM CNRS, 38000 Grenoble, France |
| Authors: | S. Liénard, Univ. Grenoble Alpes, LTM CNRS, 38000 Grenoble, France D. Sam-Giao, Sofradir, BP 21-38113, Veurey-Voroize, France A. Kerlain, Sofradir, BP 21-38113, Veurey-Voroize, France F. Boulard, Univ. Grenoble Alpes, France C. Vallée, Univ. Grenoble Alpes, France |
| Correspondent: | Click to Email |
Physical vapor depostion is a mature, well understood and established technology in integrated circuit fabrication. CdTe and ZnS binary II-VI compounds materials are commonly used in photovoltaic solar cells or infrared optics. However, sputtering deposition of these materials still suffer from a lack of comprehensive study to optimize process integration.
Our study is focused on the influence of projectile ions mass on properties of sputtered deposition CdTe and ZnS films. We compare physico-chemical, mechanical and electrical properties of CdTe and ZnS films deposited with Ar and Xe ions as sputter gas. Ar and Xe concentration in these films are characterized by Time of Flight Secondary Ions Mass Spectrometry (TOF-SIMS). Dedicated implanted reference samples are used to quantify the absolute concentration. Layers microstructures are characterized by Scanning Tunneling Electron Microscopy (STEM) and dielectric constant by capacitance-voltage measurements. We use the curvature method based on the well known Stoney concept [1] to calculate film stress while density is estimated by differential weighing.
With Ar ion deposition process (low sputter on target mass ratio), we observe Ar and cavities inside the CdTe layer. The density as well as the dielectric constant are below bulk values. A good agreement is found between the cavity density and the effective dielectric constant determined by the Bruggeman model [2-3]. on the contrary, Xe ion target sputtering (high sputter on target mass ratio) leads to denser films, without Xe inside the layers, and close to theory density and dielectric constant values. We discuss these observations in terms of backscattered ions incorporation. Moreover, the effect of thermal annealing time on stress evolution is discussed in regards of Ar or Xe incorporation and outgasing.
[1] G.G. Stoney, Proc. Soc. London, A82, 1909, 172
[2] Aspnes D. E., Thin Solid Films 89 (1982) 249.
[3] Othman M.T., PhD “Spectroscopic Ellipsometry Analysis of Nanoporous Low Dielectric Constant films Processed via Supercritical CO2 for Next-generation Microelectronic Devices”., University of Missouri-Columbia, 2007