On the Deposition Rates of Magnetron Sputtered Thin Films at Oblique Angles

Abstract

We describe the magnetron sputtering deposition of thin films at oblique angles. A general relation between the deposition rate of the film and experimental parameters such as gas pressure or substrate tilt angle is deduced and experimentally tested. The model also permits the direct determination of the thermalization mean free path of the sputtered particles in the plasma gas, a key magnitude defining the balance between ballistic and diffusive flows in the deposition reactor. The good agreement between experimental and calculated results supports the validity of our description to explain the main features of the magnetron sputtering deposition of thin films at oblique angles.

Influence of the sputtering flow regime on the structural properties and magnetic behavior of Fe-Ga thin films (Ga ∼ 30 at.%)

“…To know the flow regime for each L, it is necessary to calculate λ. FollowingÁlvarez et al [18], we use the expression…”

“…For example, neutrals (atoms ejected from the target upon the impact of energetic particles) suffer collisions during their movement from target to substrate [18][19][20]. If the number of collisions is low, neutrals keep their momentum and energy until the substrate and the sputtering process takes place under ballistic flow [18]. However, neutrals lose their kinetic energy and momentum, reaching the substrate just with thermal energy if the number of collisions is large enough to produce their thermalization [21].…”

“…Although several papers deal with the growth of Fe-Ga thin films by sputtering [11][12][13][14][15][16][17], the impact of different phenomena occurring during sputtering deposition has not been completely clarified or quantified. For example, neutrals (atoms ejected from the target upon the impact of energetic particles) suffer collisions during their movement from target to substrate [18][19][20]. If the number of collisions is low, neutrals keep their momentum and energy until the substrate and the sputtering process takes place under ballistic flow [18].…”

Growth and thermal oxidation of Ru and ZrO2 thin films as oxidation protective layers

“…The sputter gas pressure is a regulator of the particle kinetic energy, becoming slower and more diffusive for higher pressures due to higher scattering, which leads to increasing amount of thermalized (random) sputtered particles and a reduction of the ballistic (straight trajectory) flux. 150,156 The effect of the gas pressure can significantly influence the structure and the morphology of the deposited films. 141,161 Therefore, this parameter has been adapted in all chapters of this thesis, together with the sputtering power, to control the deposition rate and the energy distribution profile of the incoming material flux, and hence controlling the final properties such as the mass density or roughness of our grown films.…”

“…The main deposition parameters include: target-substrate distance and target-substrate angle, 150,151 sputtering power, 152 substrate bias, 153 target self-bias, 154 and sputter gas (type, pressure, and mixture composition for reactive sputtering). 155,156,157 From all these parameters, the relevant ones, which are varied in this thesis are: the sputtering power, and both sputter gas pressure and mixture composition (in the case of reactive sputtering). These three relevant deposition parameters are discussed as follows.…”