AlN Thin Films Deposited By MF Reactive Magnetron Sputtering

AlN is one of the ideal heat sink materials for its large thermal conductivity. It is widelyused in many fileds for its high breakdown field, high band gap, high chemical and thermalstability and so on. Since AlN thin films can be prepared by various methods, the properties ofAlN thin films have a big gap. In this research, AlN thin films were deposited by MF reactivemagnetron sputtering with ion source. This study explored the process of preparing AlN thinfilms by using a three element （N₂flow, bias, working pressure） and four levels orthogonalexperiment. Then, the influence on AlN thin films, of which preparation process, were basedon the selected process from the orthogonal experiment were explored by changing bias, ionsource power, temperature and respectively. The structure and properties of AlN thin filmswere characterized by scanning electron microscope（SEM）, X ray diffraction instrument（XRD）, Micro hardness tester, scratch tester and flash tester.The results show that: in the orthogonal experiment, the N₂flow play a dominant role inthe film deposition rate and adhesion strength of AlN thin films. Bias has the biggestinfluence on the hardness. Its optimal level is100V in the four level. Although the influenceof working pressure on the qualities of AlN thin flims is not the biggest, large workingpressure would decrease the deposition rate. The SEM micrographs of3#process AlN thinfilms is the best in the sixteen process of orthogonal experiment. The XRD show that there isAlN phase, but the percentage is not big. Considering the comprehensive properties ofsamples,3#is the optimal preparation process. The related parameters are working pressure0.3Pa, bias100V, N₂50sccm.In the research of the influence of single parameter on the AlN thin films’ qualities:（1）When the bias is100V, the thickness and hardness of AlN thin films are the biggest. Withthe bias increasing, the density and adhesion strength of AlN thin films are significantlyincreased, but the films’ deposition rate and the hardness are reduced.（2）The AlN phase isincreased with the power of ion source. The AlN films show （100） orientation obviously whenthe ion source power is more than0.7kW; the AlN thin films have the trend to amorphoustransition when the ion source power is1.3kW. What’s more, the density and adhesionstrength of AlN thin films are obviously increased, but the film deposition rate and hardnessincrease firstly and then decrease with the addition of ion source power.（3）With thetemperature increasing, the hardness of AlN thin films is also increased. The thickness of AlNthin films is firstly increased and then decreased. However, the adhesion strength of AlN thin films has the opposite trend. AlN thin films has the best surface morphology in200℃. If thetemperature is too high, the AlN thin films deposited would happen to lattice distortion.（4）The thermal conductivity of substrate Al is195.23W/（m·K）. Deposted AlN thin films onthe substrate, the thermal conductivity is obviously improved.（5） Ion source power is themost significant factor on the quality of AlN thin films in the three parameters: bias, ionsource power, temperature.