DC sputtering of highly c-axis AlN films on top of 3C-SiC (111)-on-Si (111) substrates under various N2 concentrations

Abstract

This article reports on the direct current sputtering of AlN thin films on top of a cubic-silicon carbide (111) on silicon (111) substrates. The authors varied the nitrogen (N2) concentrations, while keeping other process parameters fixed at the power of 1200 W, the substrate temperature of 350 °C, the target to substrate distance of 20 cm, and the sputtering pressure of 2 mT. The total N2/Ar gas flow is 50 sccm, and the poison mode starts at 40%. The x-ray diffraction results show that the AlN films are highly oriented along the (002) orientation at various N2 concentrations. The values of the three parameters support this observation, namely, (1) the extracted full width at half maximum (FWHM) of (002) diffraction peaks with the median of 0.28° and the standard deviation of 0.012°, (2) the area of AlN (002) under the curve is between 92% and 97%, and (3) the grain sizes are between 30.11 and 32.3 nm. The omega scan rocking curve of two samples at 40% and 80% N2 concentrations depicts good quality AlN (002) films with the FWHM values of 1.5° and 2°, respectively. The relationship between the N2 concentrations and the film's properties is elucidated. Finally, the authors discuss the effect of the lattice mismatch of 1% between AlN (002) and 3C-SiC (111).

The sputtering of AlN films on top of on- and off-axis 3C-SiC (111)/Si (111) substrates at various substrate temperatures

“…The choices of sputtering power that can be selected are DC, pulsed DC or RF. From the previous experiment [17], the reactive gas i.e. N2 formed a coating (insulator) on the target that would lead to the arcing and instabilities using the DC power.…”

“…The pulsed DC sputtering of the AlN thin films on top of the 3C-SiC-on-Si (111) substrates was performed using a magnetron sputtering system (Gamma 1000, Surrey Nano Systems, Newhaven, UK) at the sputtering power of 1800 W. This value has been determined to be the optimized power from previous experiment [17]. The pulsed DC power supply (Pinnacle Plus, Advanced energy, Fort Collins, USA) was utilized at 250 kHz with the time off of 0.4 µs to avoid the electrical arcing.…”

“…One practical solution was to employ the 3C-SiC buffer layer to reduce the CTE difference to 18%, which was done by our group. In our previous work [17], we investigated the influence of Nitrogen (N2) concentration on the crystal quality of the c-axis oriented AlN thin film on top of a Si (111) substrate with a 3C-SiC (111) buffer layer. However, we experienced arching issue with the DC sputtering system.…”

Reactive Sputtering of Aluminum Nitride (002) Thin Films for Piezoelectric Applications: A Review

“…For each parameter, selected works that investigate its effect will be mentioned. In addition to using the works that were already summarized in Table 2 , i.e., references [ 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 ], we also highlight additional articles that are not included in that table i.e., references [ 63 , 64 , 65 , 66 , 67 , 68 , 69 , …”

“…The group who needed the pure N 2 concentration argued that the closed-pack (002) plane could only be assembled with lower surface energies, where N 2 particles dominate. The details of both theories and their implications could be read in reference [ 69 ]. It should be noted that this is our own paper.…”