Deposition Kinetics of Thin Silica-Like Coatings in a Large Plasma Reactor

Abstract

An industrial size plasma reactor of 5 m3 volume was used to study the deposition of silica-like coatings by the plasma-enhanced chemical vapor deposition (PECVD) method. The plasma was sustained by an asymmetrical capacitively coupled radio-frequency discharge at a frequency of 40 kHz and power up to 7 kW. Hexamethyldisilioxane (HMDSO) was introduced continuously at different flows of up to 200 sccm upon pumping with a combination of roots and rotary pumps at an effective pumping speed between 25 and 70 L/s to enable suitable gas residence time in the plasma reactor. The deposition rate and ion density were measured continuously during the plasma process. Both parameters were almost perfectly constant with time, and the deposition rate increased linearly in the range of HMDSO flows from 25 to 160 sccm. The plasma density was of the order of 1014 m−3, indicating an extremely low ionization fraction which decreased with increasing flow from approximately 2 × 10−7 to 6 × 10−8. The correlations between the processing parameters and the properties of deposited films are drawn and discussed.

Langmuir Probe Diagnostics with Optical Emission Spectrometry (OES) for Coaxial Line Microwave Plasma

“…Here, Vs is the space potential, I e is the electron current, I e0 is the saturation electron current. Equation ( 4) can be achieved by transforming Equation (2). Equation (4) shows that the slope of the (ln I)-Vp curve is exactly 1/TeV (which is convenient to write kTe/e as Te/V, the electron temperature in eV) and is a good measure of the electron temperature [5,7].…”

“…In industrial plasma processing, such as microwave plasma chemical vapor deposition (PECVD) [1][2][3], it would be useful to directly control plasma properties such as electron temperature and density [4]. For plasma diagnostics, the Langmuir is widely used [5,6].…”

Distribution of the Deposition Rates in an Industrial-Size PECVD Reactor Using HMDSO Precursor

“…The correlation was obtained by an appropriate calibration and processing of acquired signals. One such sensor was already used in our previous work [26], where the deposition rates measured with such sensor in real time were the same as those measured with time-consuming post-deposition surface analysis such as atomic force microscopy (AFM) (Solver PRO, NT-MDT, Moscow, Russia), X-ray photoelectron spectroscopy (XPS) (TFA XPS Physical Electronics, Münich, Germany) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) depth profiles (ToF-SIMS 5 instrument, ION-TOF GmbH, Münster, Germany).…”