Application of thin Au/Ti double-layered films as both low-temperature bonding layer and residual gas gettering material for MEMS encapsulation
Application of thin Au/Ti double-layered films as both low-temperature bonding layer and residual gas gettering material for MEMS encapsulation
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DOI：
10.1016/j.mee.2021.111513
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发表时间：
2021-02-01
影响因子：
2.3
通讯作者：
Takagi, Hideki
中科院分区：
文献类型：
--
作者：
Kurashima, Yuichi;Matsumae, Takashi;Takagi, Hideki
在这项研究中，我们评估了薄Au/Ti双层膜作为微机电系统（MEMS）封装中残留气体的粘合层和吸杂材料的适用性。在具有热SiO2膜的Si衬底上的薄Au/Ti膜在大气中在400 ℃的最高温度下退火1小时，以检查通过Ti原子通过Au膜扩散到表面的吸气剂活化。X射线光电子能谱测量表明，在Au膜下的Ti原子通过在200 ℃以上的温度下的吸气剂活化退火扩散到表面。通过拉伸试验、扫描声学显微镜（SAM）和透射电子显微镜（TEM）研究了Si衬底上Au/Ti薄膜的键合特性。在200摄氏度或低于200摄氏度的结合前退火的情况下，在使用SAM的结合界面处没有观察到明显的空隙，并且在拉伸测试之后在结合界面处没有观察到剥离。相比之下，在300摄氏度的预结合退火下，膜不能结合。在200 ℃或低于200 ℃的键合前退火后制备的键合界面处，即使在300 ℃的键合后退火后，使用截面TEM也没有观察到明显的空隙，300 ℃是作为吸杂层活化所需的温度。结果表明，Au/Ti薄膜既可作为MEMS封装的键合层，又可作为吸气剂材料。
In this study, we evaluated the applicability of thin Au/Ti double-layered films as both bonding layers and gettering material for residual gases in micro-electromechanical system (MEMS) packaging. The thin Au/Ti films on Si substrates with thermal SiO2 films were annealed at a maximum temperature of 400 degrees C for 1 h in atmospheric air to examine getter activation by the diffusion of Ti atoms to the surface through the Au film. X-ray photoelectron spectroscopy measurements revealed that the Ti atoms under the Au film diffused to the surface by the getter activation annealing at temperatures above 200 degrees C. The bonding characteristics of the thin Au/Ti films on the Si substrates were inspected through tensile tests, scanning acoustic microscopy (SAM), and transmission electron microscopy (TEM). With pre-bond annealing at or below 200 degrees C, no significant voids were observed at the bonding interfaces using SAM, and peeling was not observed at the bonding interface after the tensile tests. By contrast, the films could not bond with pre-bond annealing at 300 degrees C. At the bonding interface prepared after pre-bond annealing at or below 200 degrees C, no significant void was observed using cross-sectional TEM even after post-bond annealing at 300 degrees C, which is the required temperature for activation as a gettering layer. The results confirm that the thin Au/Ti films are applicable as both bonding layers and getter materials for MEMS packaging.