Target heating and plasma dynamics during hot magnetron sputtering of Nb

Abstract

In this work, the direct current (DC) hot magnetron sputtering (HMS) of Nb has been studied and compared with the conventional cold magnetron sputtering (CMS) discharge. Particularly, these two magnetron systems were investigated in terms of current-voltage trends, behaviour of spectral lines, target temperature, and deposition rate. The current-voltage evolution showing strong variations over time in the HMS system was used to monitor the moment when a thermionic emission becomes considerable. Meanwhile, thanks to the time-resolved optical emission spectroscopy (OES), the dynamics of plasma particles and the population of their electronic levels were analysed as a function of the target temperature. The target temperature was measured owing to both pyrometry and OES-based approach, i.e., by fitting an emission spectrum baseline. Finally, in the configuration used in this work, the deposition rate up to 100 nm/min was obtained at the applied power density of 30 W/cm2, which is 3 times higher than the maximum power density applicable to the classical CMS system. However, with further increase in the power density, the deposition rate values were found to be saturated, which is likely caused by a significant increment in a number of thermal electrons in the discharge area.

Ion formation in thermionic-emission-assisted hot magnetron sputtering discharge

“…Ar has been used as a working gas with the pressure of 1 Pa to ignite DC magnetron sputtering discharge. The target temperature has been measured based on the Planck's radiation curve fitting, as explained elsewhere [4].…”

“…First, it allows applying a higher electrical power density to the source, i.e. to increase the target erosion rate, without a risk to overheat the magnets inside the cathode [4]. Second, target heating by ion bombardment may lead to evaporation or sublimation of particular materials and increase the deposition rate several times [5].…”

Simulation of Target Surface Chemical State in a Hot-Target Hipims Process

“…Deposition of single-material films in hot-target magnetrons has been studied in a number of recent papers, including Sn, Cu, Cr, Si, Ni, Fe, Ge, Ti [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26].…”