ZrB2 thin films grown by high power impulse magnetron sputtering from a compound target

Abstract

ZrB 2 thin films were grown on Si by high power impulse magnetron sputtering (HiPIMS) from a compound target in an industrial deposition system. By keeping a constant average power while modifying the HiPIMS pulse repetition frequency, the pulse peak current and thereby the degree of ionisation was varied. The films were characterised using X-ray diffraction techniques, scanning electron microscopy, time-of-flight elastic recoil detection analysis, and four-point probe measurements. It was found that the composition of the films matched closely that of the target material, and the films were low in contamination. The films were crystalline with a strong (000n) preferred orientation, and that the residual stress could be adjusted, from tensile to compressive, by increasing the degree of ionisation. The film morphology appeared dense, with a smooth surface, and the resistivity was found to range from 180 to 250 µΩcm with no clear dependence on frequency in the investigated parameter range.

Direct current magnetron sputtered ZrB2 thin films on 4H-SiC(0001) and Si(100)

“…SEM analysis shows a columnar growth for ZrB2 on Si(100), see Figure 6 for (a) a film deposited at RT and a substrate bias of -80 V and (b) at 550 °C and a substrate bias of -80 V. This behavior is in agreement with the results obtained for DCMS sputtered films in the study of Samuelsson et al [7]. Furthermore, the surface of the deposited films is in general smooth, in particular for films deposited at RT and with a bias voltage > -40 V, which is in accord with the results from the HRTEM investigation.…”

“…This result is in contrast to Mitterer et al who found that the B/Zr ratio increased with increasing deposition temperature [9]. However, the condition that a high bias favors a Zr-rich composition is in accord with previous studies, as re-sputtering of boron during growth of ZrB2 from a compound target have been proposed by Mitterer et al [9] and Samuelsson et al [7], using DCMS and high power impulse magnetron sputtering, respectively. It is likely that a preferential re-sputtering process at moderate bias voltage of -80 V, as applied in our experiments, is eased at elevated temperatures.…”

“…However, the resistivity values of our films are comparable to other magnetron sputtered films that show resistivity values ranging between 160 and 440 µΩcm [7,10,16,17,35].…”

“…This indicates either a textured or an epitaxial growth to 4H-SiC(0001). A 0001 preferred orientation for ZrB2 films deposited on substrate materials such as Si(100), molybdenum, and steel at low growth temperatures has been reported in the literature [7,8,28]. As the substrate temperature is increased the intensity of the 0001 peak reduces and the 0002 peak becomes absent.…”

“…The literature shows that ZrB2 films have been deposited by physical vapor deposition (PVD) [7][8][9][10], as well as chemical vapor deposition (CVD). [11,12].…”