Metastable ternary concentration diagram of phase formation in are-deposited films Ti-Si-N(O) (C-Si < 30 at.%) at T (dep) = 300-500 K is presented in this paper along with comparison of the diagram with equilibrium isothermal cross-sections of Ti-Si-N and Ti-Si-O systems. At a temperature of 300 K and C-Si > 10-15 at.% a transition takes place from metastable supersaturated cubic solution TiSixNyOz to amorphous state TiSixNyOz. Intermediate bi-phase area (TiSixNyOz + Ti5Si3 (O,N) with heterogeneous structure, preceding forming an amorphous state, was found. In the context of the heterogeneous nucleation, kinetics of the deposition of the phases TiSixNyOz, Ti5Si3(O,N) was analyzed. It was shown that heterogeneous microstructure of these films and concentration range ton silicon) of the forming bi-phase area is defined by energy parameters of growth kinetics of critical Ti5Si3 (O,N) crystal nucleus. Applicable to the system Ti-Si-N(O) (C-Si < 30 at.%) criterion of forming an amorphous phase TiSixNyOz was considered. Amorphous structures in are-condensed films of Ti-SiN(O) (15 < C-Si < 30 at.%) were established to be characterized with a short-range compositional ordering of silicon and titanium atoms. Nitrogen (oxygen) atoms occupy either the positions of silicon atoms or pores in the amorphous TiSix framework, and Ti-N(O) bonds are more preferable as compared to Si-N(O) bonds.