Thermal Oxidation of Tungsten Coatings for Detection by Infrared Spectrometry Method

Abstract

Physical vapor deposition (PVD) of metallic thin films is used extensively in the fabrication of semiconductor technology devices - use as of lately for them have grown. Tungsten (W) is a low resistivity, refractory metal, that is often deposited by PVD methods for use as a gate contact to semiconductor devices and due to the low work function and high thermal stability, W can be used for the fabrication of field emitters in microelectronics [1-3]. In order to monitor quality of the synthesized thin films by magnetron sputtering method, it is necessary to develop methodology suitable for the analysis of these thin films. Infrared spectrometry is a sensitive method for the analysis of chemical bonds, but W thin films contain weakly polar and non-polar W-W bonds, that cannot be directly detected by infrared spectrometry, therefore oxidation of W is selected as thermal oxidation method for detecting oxidized products for thin films of thickness 150 nm, for instance, W-O bonds. After oxidation, it was observed, that the oxidation of W thin films takes place already at a 600 °C in the air atmosphere. The Fourier transform infrared spectrometry (FTIR) spectra of modified coatings showed formation of additional new signals in the region of 700-900 cm−1 attributed to W-O, O-W-O, W=O bonds - formation of W-oxygen bonds on Si-SiO2 substrate was achieved. For coating homogeneity and production quality formation, additionally synthesized control samples are recommended for FTIR analysis.

Estimation of Thermal Stability of Si-SiO2-W Nanolayered Structures with Infrared Spectrometry

“…Meanwhile, in the samples where the Si-SiO 2 is covered with the W layer, the resulting FTIR spectrum intensity is almost a straight line, which is explained by the metallic properties of W and an absence of polar bonds in the metallic W coating. This observation allows us to estimate the coverage efficiency of the Si-SiO 2 with W and can be used as an indicator for analyzing the stability of the layers under various exposure conditions, such as oxidation at high temperatures [ 32 ].…”

“…The corresponding surface morphologies are shown in Figure 5, while the element distributions of the non-treated and thermally treated samples are shown in Figure 6. The signals in the FTIR spectra include peaks at about 435 cm −1 , corresponding to Si-O bending; 515 cm −1 , for Si-O-Si bonds; 565 cm −1 , for Si-O-Si bending; 600-630 cm −1 , for Si-Si asymmetric vibrations [32]; 700, 740, and 780 cm −1 , for Si-O-Si symmetric stretching; 825 and 910 cm −1 , for Si-O asymmetric vibrations; 960 cm −1 , for Si-O-Si bonds [35]; and 1010 and 1110 cm −1 , attributed to Si-O-Si bonds [36][37][38].…”

Tungsten–SiO2–Based Planar Field Emission Microtriodes with Different Electrode Topologies

“…Sin tip cathodes may also be preferred in applications where a high degree of special res tion is required, which is provided by the small size and sharpness of the emitting tip Furthermore, we evaluate the quality of the layers of the fabricated microtriode analyzing their surface roughness, elemental composition, and work function. The mal properties and infrared spectroscopic analysis of the microtriode layers have described in other works [21,22].…”

“…Furthermore, we evaluate the quality of the layers of the fabricated microtriodes by analyzing their surface roughness, elemental composition, and work function. The thermal properties and infrared spectroscopic analysis of the microtriode layers have been described in other works [21,22].…”