XPS analysis of thin chromium films

Abstract

The surface and mechanical properties of thin Cr films play an essential role in microphotolithographic processes in which an inorganic photoresist based on vacuum-evaporated As,S, is used as a light-sensitive system. The present paper reports some XPS data about thin chromium layers obtained by thermal evaporation, high-frequency sputtering, electron beam evaporation and dc magnetron sputtering. A correlation is found between the surface elemental composition of the metal coating and the possibilities of obtaining good adhesion between the Cr and As& used as the inorganic photoresist. It is shown that the presence of pure Cr on the surface of the samples is a defining condition for photolithography in the submicron region. I N T R O D U C T I O N EXPERIMENTALThe use of thin chromium films for the preparation of metal photomasks in photolithography has increased the interest in studying the main photochemical properties of such films.'-4 The surface and mechanical properties of the chromium coatings are very essential in microlithographic processes using an inorganic photoresist based on vacuum-deposited As2S3 as a lightsensitive ~y s t e m .~ The small thickness of the chalcogenide layer and its amorphous structure allow the reproduction of details with a line width down to 0.35 pm. However, this is possible only if the adhesion between the As2S3 layer and the metallized glass substrate is good. The surface and bulk properties of chromium samples have been of special interest in publications applying AES and XPS methods of analysis.'.6 A system of spectral characteristics of different standards containing Cr has been obtained and it has been shown that during deposition of Cr films by thermal evaporation the contamination of the layers with oxygen and carbon is lower at higher temperatures of the substrate. The reactive properties of thin chromium films obtained by vacuum evaporation have been comparatively well studied.'Regardless of the available information and the experiments performed to determine the elementary composition of the Cr coatings, the above investigations have been more or less methodological in character.The present paper reports some XPS data on thin chromium films obtained by thermal evaporation, highfrequency sputtering, electron beam evaporation and dc magnetron sputtering. The study is performed to explain the correlation between the adhesion of the vacuum-deposited As,S, layers used as inorganic photoresist and the properties of the metal films. The XPS studies were carried out in an Escalab Mk I1 (VG Scientific) electron spectrometer with base pressures in the preparation and analysis chamber of -2 x lo-* and -1 x lo-* Pa, respectively. The photoelectron spectra were excited with a twin-anode x-ray source (Mg Ka at 1253.6 eV and A1 Ka at 1486.6 eV). The instrumental resolution measured as the full width at half-maximum (FWHM) of the Ag 3d,,, photoelectron peak was 1.2 and 1.3 eV for the two sources, respectively. Experiments were carried out with Mg Ka exitation. The photoelectron lines...

Effect of crystallinity of Co layer on perpendicular exchange bias in Au-capped ultrathin Co film on Cr2O3(0001) thin film

“…Moreover, the XP spectra are reproduced by two mixed Lorentz/Gaussian functions, as shown by thin solid lines. The peak at the binding energy of metallic Cr (574.1-574.8 eV [21,22]) is not observed, showing that no metallic Cr is present in our Cr 2 O 3 layer. In the XP spectra of O 2 À , a single peak at 531.1 eV is observed, which is well fitted by mixed Lorentz/Gaussian functions.…”

“…4(a), two peaks are observed at 577.1 and 586.6 eV. The binding energies are in the range of the literature values for Cr2p 3/2 and Cr2p 1/2 in Cr 2 O 3 [21,22]. Moreover, the XP spectra are reproduced by two mixed Lorentz/Gaussian functions, as shown by thin solid lines.…”

“…In the XP spectra of O 2 À , a single peak at 531.1 eV is observed, which is well fitted by mixed Lorentz/Gaussian functions. The observed peak is near the binding energy of O1s in oxides [21,22]. The valence states of the Cr and O ions also indicate that no other oxide phase or metallic Cr is included in our Cr 2 O 3 layer.…”

Study of Topography and Distribution State of the Nanoscale Passivation Film on a Rough Tinplate Surface

“…The measured and fitted Cr2p peaks are shown in Figure 13. The binding energy values of the fitting peaks are listed in Table 6 and the chemical composition of the film was obtained by referring to the relevant literature [8,33,[41][42][43] and comparing the binding energy values. The chemical passivation film is only composed of Cr 2 O 3 .…”

Fabrication of a Cr thin‐film AEM characterization standard

“…Although the Cr film does not contain a known amount of a light element, which would be useful both for calibrating and measuring the low‐energy efficiency of light‐element X‐ray energy dispersive spectrometry (XEDS) detectors, it does offer resistance to thermal and ballistic damage up to 400 kV ( Zaluzec & Mansfield, 1987). Cr is also known to produce a thin (≈ 5 nm) protective oxide film in storage ( Petkov et al ., 1992 ), so that aged Cr is protected by a layer of Cr 2 O 3 which is not likely to experience electron radiation damage in the AEM. Another beneficial characteristic of Cr is the low surface mobility which prohibits the growth of large grains during deposition ( Goldstein et al ., 1992 ).…”