The Effect on Physical, Electrical and Structural Parameters of RF Sputtered Molybdenum Thin Film

Abstract

In this study, the physical, electrical, and structural parameter on radio frequency (RF) sputtered molybdenum thin film is investigated as a function of two deposition parameters: rf power, and argon (Ar) pressure. Films are sputtered onto the substrates nominally held in room temperature in a RF sputtering system at partial argon (Ar) pressure. A number of 10 films are deposited at 8 sccm of Ar pressure while varying the rf power from 90 to 360 watt. Besides, another set of 7 films are deposited at 240 watt RF power while varying the Ar pressure from 8 to 32 watts. All the films are characterized using FESEM, AFM, XRD, and four points probe. The analysis results substantiate that, to fabricate a low resistive thin layer of molybdenum (Mo) both sputtering power, and deposition time Ar pressure plays significant rules. It is found that, with the increase of the RF power (90 to 280 watt) the deposition rate increase from 1.2 A0/sec to 4.4 A0/sec. But at a RF power higher than 280 watt the deposition rate saturated and it does not increase as linear as before. Also resistivity continuously decreases as the RF power increases from 90 watt up to 270 watt, after that the resistivity remain almost same regardless the RF power increased. Besides, by varying the Ar pressure it is found that with the increase of the Ar pressure the deposition rate increase until 20 sccm (up to 2.4 A0/sec). With further increase of the Ar pressure deposition rate start reducing and reached 2.1 A0/sec at 32 sccm. Based on the above investigation and analysis optimized film is deposited and further analyzed. The surface roughness is analyzed using AFM characterization tool and found 27.4519 nm. The FESEM and XRD analysis along with the resistivity of the film is used to measure the strain of the deposited film and found a strain of less than 0.01% on the optimized film, which is essential for MEMS/NEMS device fabrication and energy harvesting applications.