It is important to note that the properties of the BC\({}_{\rm x}\)N\({}_{\rm y}\) films depend on a type of CVD process, the precursors' nature, their concentration in the initial gas mixture, the type of additional gases, as well as on the reactor chamber geometry, the substrate temperature, the total pressure of the gas mixture in the reactor, the parameters of the plasma generator (in case of PECVD processes), laser wavelength and power (in case of LCVD processes), and other deposition parameters appropriate to a particular method. To obtain BC\({}_{\rm x}\)N\({}_{\rm y}\) films in CVD processes, volatile boron fluoride, boron chloride, and diborane can be used as a source of boron and sources of carbon (hydrocarbons or CCl\({}_{4}\)) and nitrogen (N\({}_{2}\), NH\({}_{3}\)), which sometimes require separate supply channels [3; 23; 24]. It should be noted that the aforementioned precursors are toxic and pyrophoric substances, the danger of which increases at high operating temperatures. A limited number of works [23; 25] dealt with the use of diborane B\({}_{2}\)H\({}_{6}\) and dimethylamine (CH\({}_{3}\))\({}_{2}\)NH, which contains two other components (nitrogen and carbon), or nitrogen with trimethylboraneB(CH\({}_{3}\))\({}_{3}\) containing both carbon and boron in the LCVD processes. The alternative way of synthesis of BC\({}_{\rm x}\)N\({}_{\rm y}\) films is through the use of organoboron compounds with various compositions and structures. They are single source-precursors containing all the necessary elements in one molecule. These compounds, including alkylamine boranes, are of special interest because the molecular structure of the initial organoboron precursor affects the chemical and phase compositions and the microstructure of deposited films [26; 27; 28; 29; 30]. They are stable under normal conditions, less toxic than volatile binary boron compounds, non-combustible, and relatively cheap [31]. One of them is trimethylamine borane (CH\({}_{3}\))\({}_{3}\)N\(\cdot\)BH\({}_{3}\) (TMAB) [32; 33]. Previously, a number of works has already been carried out using TMAB as a precursor. Table 1 contains the data on the conditions of the CVD syntheses of the BC\({}_{\rm x}\)N\({}_{\rm y}\) films from TMAB and their chemical composition and functional properties. As one can see, the main attention was paid to LPCVD and RF-PECVD methods. To date, there are relatively few studies devoted to the MW-PECVD technique. An important advantage of using plasma-activated processes is a decrease in the film synthesis temperature. The literature analysis and results summarized in Table 1 show that special attention was devoted to the determination of elemental composition, chemical structure and mechanical characteristics of BC\({}_{\rm x}\)N\({}_{\rm y}\) films depending on the film growth conditions. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multicol  
BC\({}_{\rm x}\)N\({}_{\rm y}\) films obtained by chemical vapor deposition are usually amorphous which was demonstrated by the conventional X-ray diffraction method. Therefore, it is generally accepted to judge their structure by the nearest atomic environment, which can be studied using spectroscopic methods such as IR-Fourier, Raman, X-ray photoelectron spectroscopy (XPS), electron energy loss spectroscopy, X-ray absorption near edge structure spectroscopy, synchrotron radiation-based total reflection X-ray fluorescence analysis combined with near-edge X-ray absorption fine structure spectroscopy (TXRF-NEXAFS), and some others. The first three of these methods are the most common and, when used together, provide information on interatomic bonds in the film's material and its local chemical structure. The elemental composition of films is significantly affected by the method of gas-phase activation. As a result of the thermal decomposition of TMAB, the boron content in the films is high, while the nitrogen content is negligible. Using PECVD processes significantly decreases the boron content and increases the content of carbon and nitrogen.