Song Yiwen, Perez Carlos, Esteves Giovanni, Lundh James Spencer, Saltonstall Christopher B, Beechem Thomas E, Yang Jung In, Ferri Kevin, Brown Joseph E, Tang Zichen, Maria Jon-Paul, Snyder David W, Olsson Roy H, Griffin Benjamin A, Trolier-McKinstry Susan E, Foley Brian M, Choi Sukwon
Department of Mechanical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.
Sandia National Laboratories, Albuquerque, New Mexico 87185, United States.
ACS Appl Mater Interfaces. 2021 Apr 28;13(16):19031-19041. doi: 10.1021/acsami.1c02912. Epub 2021 Apr 14.
Radio frequency (RF) microelectromechanical systems (MEMS) based on AlScN are replacing AlN-based devices because of their higher achievable bandwidths, suitable for the fifth-generation (5G) mobile network. However, overheating of AlScN film bulk acoustic resonators (FBARs) used in RF MEMS filters limits power handling and thus the phone's ability to operate in an increasingly congested RF environment while maintaining its maximum data transmission rate. In this work, the ramifications of tailoring of the piezoelectric response and microstructure of AlScN films on the thermal transport have been studied. The thermal conductivity of AlScN films (3-8 W m K) grown by reactive sputter deposition was found to be orders of magnitude lower than that for -axis-textured AlN films due to alloying effects. The film thickness dependence of the thermal conductivity suggests that higher frequency FBAR structures may suffer from limited power handling due to exacerbated overheating concerns. The reduction of the abnormally oriented grain (AOG) density was found to have a modest effect on the measured thermal conductivity. However, the use of low AOG density films resulted in lower insertion loss and thus less power dissipated within the resonator, which will lead to an overall enhancement of the device thermal performance.
基于AlScN的射频（RF）微机电系统（MEMS）正因其可实现的更高带宽而取代基于AlN的器件，适用于第五代（5G）移动网络。然而，射频微机电系统滤波器中使用的AlScN薄膜体声波谐振器（FBAR）过热限制了功率处理能力，进而限制了手机在日益拥挤的射频环境中保持最大数据传输速率时的运行能力。在这项工作中，研究了调整AlScN薄膜的压电响应和微观结构对热传输的影响。通过反应溅射沉积生长的AlScN薄膜（3 - 8 W m K）的热导率由于合金化效应，比c轴织构的AlN薄膜低几个数量级。热导率对薄膜厚度的依赖性表明，由于过热问题加剧，更高频率的FBAR结构可能会受到功率处理能力有限的影响。发现异常取向晶粒（AOG）密度的降低对测量的热导率有适度影响。然而，使用低AOG密度的薄膜会导致更低的插入损耗，从而使谐振器内耗散的功率更少，这将导致器件热性能的整体提高。
