Nanometer‐Scale Depth‐Resolved Atomic Layer Deposited SiO₂ Thin Films Analyzed by Glow Discharge Optical Emission Spectroscopy

Abstract

In this contribution, pulsed radio frequency (rf ) glow discharge optical emission spectroscopy (GDOES) is used to investigate the film properties of SiO 2 deposited by plasma enhanced atomic layer deposition (PEALD), for example, the chemical composition, structural properties and film thickness. The total sputtering time until the interface between the SiO 2 layer and the Si substrate is %13 s. The main impurities in the film, that is, H, C, and N, are detected. It is observed that both C and N intensities decrease with increasing plasma power during deposition of the thin film. The higher plasma power seems to increase the reactivity of the PEALD process and consequently, it might reduce the concentration of impurities in the deposited film. Moreover, the deviation of the GDOES sputtering rates on the film are related to the film density. The thickness of one-hundred-nanometer range SiO 2 film is calculated from the GDOES silicon and oxygen emission profiles, and its difference from ellipsometry and X-ray reflectivity measurements highlights the challenges for the GDOES technique for transparent thin films. Experimental SectionPEALD SiO 2 films deposited on 7 Ω cm, P-doped, (100)-oriented Czochralski silicon polished substrates from bis(tertiary-butylamino)silane (BTBAS) and O 2 plasma with different powers (50, 180, and 300 W) were analyzed in this study. All depositions were done with a Beneq TFS 200 ALD-reactor using a capacitively coupled plasma source at 90 C.

Low-Temperature Plasma-Enhanced Atomic Layer Deposition of SiO2 Using Carbon Dioxide

“…As displayed on the figure, although the intensity of H in “SiO1” is slightly lower than in the other samples, taking into consideration error margins, no significant effects of plasma exposure time on the Si, O, and H contents are observed. This finding is similar to plasma power effects reported in our previous work on PEALD SiO 2 grown using BTBAS and O 2 plasma [22]. In the case of N content, the intensities for “SiO1” and “SiO3” are rather constant, whereas a lower intensity is measured for “SiO6.” This suggests that N impurity removal is more effective during the film densification.…”

“…PEALD SiO 2 films were grown on Si(100) and sapphire substrates at 90 °C using CO 2 (99.5%, Air Products) plasma as oxygen source and bis(tertiary-butylamino)silane (BTBAS) (97%, Strem Chemicals) as Si precursor [22]. The processes were carried out in a Beneq TFS 200 reactor with a remote plasma system using a capacitively coupled 13.56 MHz radio frequency (rf)-operated source.…”

“…The elemental intensities were reported as values integrated over the whole film thickness as described in Ref. [22]. For TOF-ERDA measurements, 40 MeV energy Br ions obtained from a 5MV tandem accelerator were directed on the measured samples.…”

“…Those processes usually require relatively high temperatures (> 150 °C) [12–16]. For processes compatible with thermally sensitive materials such as organic, biological, and polymeric materials, the catalyzed ALD [17–19] and plasma-enhanced atomic layer deposition (PEALD) [9, 20–22] have been used as an effective solution with process temperatures below 100 °C. However, the commonly used H 2 O and O 2 -based oxidants can lead to material degradation in the case of moisture/oxygen sensitive materials.…”

Deposition and Characterization of RP-ALD SiO2 Thin Films with Different Oxygen Plasma Powers

“…The distance between the sensing point and the substrate was 430 mm. According to a research study carried out by the Zhen Zhu group, there is a recognizable effect of the oxygen plasma power on the SiO 2 thin films’ impurity levels [ 22 ]. The OES method has also proven to be useful as a tool for the monitoring of film deposition by PECVD [ 23 ].…”