Aluminum Nitride Films for Surface Acoustic WaveDevice Applications

• Main Authors: Feng-Kun Cheng, 鄭豐昆
• Other Authors: Fu-Der Lai
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/93980713541239707087

碩士 === 國立高雄第一科技大學 === 光電工程研究所 === 94 === Abstract This thesis focus on the growth the c-axis preferred orientation (002) oriented of aluminum nitride (AlN) thin film on Si(100) wafer using DC-reactive magnetron sputtering. We use the Al metal target (99.999% purity) at the in-line sputtering system and adopt a high-purity Ar and N2 as the reaction gas. The experimental parameters are the target to substrate distance is 3cm, Sputtering pressure is 2 mTorr, the N2 contamination is 50%, the sputtering current was varied in the range from 3.5 to 4.5A, and the deposition time is 60 min. The target surface accumulate the nitrides and will decrease the deposition ration of AlN and increase the X-ray diffraction intensity of (002) orientation of AlN because the DC-reactive magnetron sputtering to deposit the AlN was used. The experimental results shows that the different grains orientation of AlN observe by X-ray diffraction (XRD) analysis when at the same deposition parameters of current. Surface acoustic wave (SAW) devices is patterned by lift-off process which is used the near field phase shift photolithography (NFPSL) to fabricate the narrow gap of a period space of IDT. The feature of process are: the narrow gap of IDT is about 180nm, the light source (I-line, λ=365nm) is adopted, the phase shifting mask (PSM) is patterned on the PDMS and the mask is consist of 10μm and 5μm. SAW devices with a high propagation velocity material (AlN) and a period space of IDT (180nm) are adopted. Based on the theoretical, the substrate of AlN(002)/Si(100) can be used to develop the higher harmonic frequency. But maybe due to the oxygen contamination of AlN, which decreased the electromechanical coupling factor. Therefore, we couldn’t effective excite the SAW perturbation on the substrate.