새로운 공정을 이용한 AlN 체적 탄성파 소자의 제작 및 다양한 금속 전극막에 따른 주파수 응답 특성 분석

Abstract

- AlN-based film bulk acoustic resonator (FBAR) devices which adopt a membrane-type configuration such as Mo/AlN/bottom-metal/Si are fabricated by employing a novel process. The proposed resonator structure does not require any supporting layer above the substrate, which leads to the reduction in energy loss of the resonators. For all the FBAR devices, the frequency response characteristics are measured and the device parameters, such as return loss and input impedance, are extracted from the frequency responses, and analyzed in terms of the various metals such as Al, Cu, Mo, W used in the bottom-electrode. The mass-loading effect caused by the used bottom-electrode metals is found to be the main reason for the difference revealed in the measured characteristics of the fabricated FBAR devices. The results obtained in this study also show that the degree of match in lattice constant and thermal expansion coefficient between piezoelectric layers and electrode metals is crucial to determine the device performance of FBAR.