This article reports on structure, phase composition and high- T oxidation resistance of sputtered Mo-Si-N films. These films were dc reactively sputtered using an unbalanced magnetron equipped with a Mo Si2 alloyed target in a mixture Ar and N2. A continuous increase of partial pressure of nitrogen p N2 from 0 to 0.6 Pa makes it possible to produce two groups of composites: (1) Mo Six +a- Si3 N4 and (2) a- Si3 N4 +Mo Nx. The composites of the first group are crystalline and contain a low amount of the a- Si3 N4 phase. On the contrary, the composites of the second group are amorphous and the a- Si3 N4 phase dominates in these films. Sputtered films were characterized using XRD, EPMA, microhardness measurements, thermogravimetric measurements and SEM. It was found that the thermal annealing of Mo-Si-N films in flowing air at temperatures Ta ≥900 °C results in a loss of the film mass (Δm<0). This loss of weight is due to the decomposition of Mo Nx>1 →Mo+ N(g) and the formation of volatile Mo Ox oxides, which diffuse out of film. This process results in (i) the formation of thin porous oxide surface layer and (ii) the loss of film mass. A very low (Δm≈0.01 mg cm3) decrease of the film mass is obtained in the case when the Mo-Si-N film contains a large (>60 vol %) amount of Si3 N4 phase and stoichiometric (x=1) or substoichiometric (x<1) Mo Nx nitride. In these films the loss of weight does not increase with increasing Ta up to 1300 °C. This fact demonstrates the high- T oxidation resistance of the a- Si3 N4 Mo Nx<1 composite. The temperature Ta =1300 °C is not a physical limit of the high- T oxidation resistance of the a- Si3 N4 Mo Nx≤1 composite but only the limit of Si substrate used in our annealing experiments. The microhardness H of the a- Si3 N4 Mo Nx<1 composite is also quite high and achieves approximately up to 25 GPa.
|Number of pages||8|
|Journal||Journal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures|
|Publication status||Published - 1 Dec 2005|
ASJC Scopus subject areas
- Condensed Matter Physics
- Electrical and Electronic Engineering