Main properties of silicides of the Mo - Si system

Abstract

Using magnetron-ion sputtering, a layer of metallic molybdenum 1–2 μm thick was deposited on the surface of a silicon single crystal grown by the Czochralski method in an atmosphere of an inert argon gas at ambient temperature. According to the results of the experiment, pure Mo layers 2 μm thick deposited by magnetron reactive sputtering from a highly pure metal molybdenum target onto a cold silicon wafer substrate with a thickness of 1.5 mm. They have simultaneously high conductivity and transparency only in the case when a strictly defined deposition rate of molybdenum metal corresponds to a given partial pressure of argon in the volume. The sputtered targets are disks 40 mm in diameter with a thickness of 3-4 mm. The technological cycle of product processing includes the stage of target cleaning. Sputtering of a metal Mo target in pure argon Ar without the addition of oxygen promotes the formation of opaque metal films with very good conductivity. X-ray diffraction analysis of silicon monocrystals with a Mo metal-coated surface revealed compounds Mo3Si and MoSi0.65 in the molybdenum-silicon system. Silicon silicide MoSi2 was found to undergo an allotropic transformation in the temperature range 1850 ÷ 1900 °C, and the low- temperature variety α-MoSi2 has a tetragonal structure. The high- temperature form of β-MoSi2 has a hexagonal structure. The results of the study with an atomic scanning microscope showed that the chains of silicon atoms, connecting with Mo atoms, form zigzags passing through the prisms of the Mo structure along parallel X and Y axes.