Investigation of plasma species, etch products and surface modification during etching of Ge, Sb and Se-based materials in CH4-H2-Ar plasmas

International audienceOrganometallic positive ions were identified in inductively coupled plasmas by means of mass spectrometry during the etching of Ge-Sb-Se materials in CH4-H2-Ar mixtures. Observation of polymetallic species (Mx-R, M = Ge, Sb, Se, x &gt; 2, R = Hy or CHz) points out that recombination reactions occur in the plasma. Correlation with x-ray photoelectron analysis, showing the presence of C-M moieties indicates that chemical etching processes take place.</div

Mass spectrometry and in situ x-ray photoelectron spectroscopy investigations of organometallic species induced by the etching of germanium, antimony and selenium in a methane-based plasma

International audienceOrganometallic positive ions were identified in inductively coupled plasmas by means of mass spectrometry during the etching of Ge, Sb, Se materials. A preliminary study was focused on identifying M x H y + (M = Ge, Sb, Se) positive ion clusters during a H 2 /Ar etching process. The methane addition to the H 2 /Ar mixture generates CH x reactive neutral species. The latter react with the metalloids within gas phase to form M x C y H z + organometallic ions. In addition, the etching of Sb 2 Se 3 and Ge 19.5 Sb 17.8 Se 62.7 bulk targets forms mixed products via ion-molecule reactions as evidenced by the presence of SeSbC x H y + ion clusters. Changes in surface composition induced by the newly formed organometallic structures were investigated using in situ x-ray photoelectron spectroscopy. In the case of the Ge and Sb surfaces, (M)–M–C x environments broadened the Ge 2p 3/2 , Ge 3d, Sb 3d and Sb 4d spectra to higher values of binding energy. For the Se surface, only the hydrogen and methyl bonding could explain the important broadening of the Se 3d core level. It was found that the Ge 39 Se 61 thin film presents an induced (Ge)–Ge–Se entity on the Ge 2p 3/2 and Ge 3d core levels