Application of thin Au/Ti double-layered films as both low-temperature bonding layer and residual gas gettering material for MEMS encapsulation

Kurashima, Yuichi; Matsumae, Takashi; Higurashi, Eiji; Yanagimachi, Shinya; Kusui, Takaaki; Watanabe, Mitsuhiro; Takagi, Hideki

doi:10.1016/j.mee.2021.111513

Cited by 12 publications

(5 citation statements)

References 25 publications

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“…Therefore, it is necessary to find a new barrier material to improve the sorption performance of the ZrCoCe getter films. For instance, Ti getter films have been widely used because of their good sorption performance and low activation temperature [ 21 , 22 , 23 ]. The densification of the Ti film can reduce the diffusion channel of active gas within, making Ti film an effective barrier layer.…”

Section: Introductionmentioning

confidence: 99%

“…In this study, Ti and ZrCoCe were deposited as barrier layers for getter films. The Ti was selected as the barrier layer material because of its sorption performance [ 22 , 24 ], whereas the ZrCoCe was chosen as the barrier layer material to simplify the process. The sorption performance, binding force, and anti-vibration properties of the ZrCoCe getter films with different barrier layer materials were studied.…”

Section: Introductionmentioning

confidence: 99%

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Influence of Barrier Layers on ZrCoCe Getter Film Performance

Shi

Xiong

Wu³

2023

Materials

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Improving the vacuum degree inside the vacuum device is vital to the performance and lifespan of the vacuum device. The influence of the Ti and ZrCoCe barrier layers on the performance of ZrCoCe getter films, including sorption performance, anti-vibration performance, and binding force between the ZrCoCe getter film and the Ge substrate were investigated. In this study, the Ti and ZrCoCe barrier layers were deposited between the ZrCoCe getter films and Ge substrates. The microtopographies of barrier layers and the ZrCoCe getter film were analyzed using scanning electron microscopes. The sorption performance was evaluated using the constant-pressure method. The surface roughness of the barrier layers and the getter films was analyzed via atomic force microscopy. The binding force was measured using a nanoscratch tester. The anti-vibration performance was examined using a vibration test bench. The characterization results revealed that the Ti barrier layer significantly improved the sorption performance of the ZrCoCe getter film. When the barrier material was changed from ZrCoCe to Ti, the initial sorption speed of the ZrCoCe getter film increased from 141 to 176 cm3·s−1·cm−2, and the sorption quantity increased from 223 to 289 Pa·cm3·cm−2 in 2 h. The binding force between the Ge substrate and the ZrCoCe getter film with the Ti barrier layer was 171 mN, whereas that with the ZrCoCe barrier layer was 154 mN. The results showed that the Ti barrier layer significantly enhanced the sorption performance and binding force between the ZrCoCe getter film and the Ge substrate, which improved the internal vacuum level and the stability of the microelectromechanical system vacuum devices.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Influence of Barrier Layers on ZrCoCe Getter Film Performance

Shi

Xiong

Wu³

2023

Materials

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“…When the Au/Ti layer was annealed, the thermally diffused Ti atoms reached the surface and reacted with the residual gas. We demonstrated that smooth Au/Ti films can form direct bonds at room temperature and absorb residual gas molecules by post-bonding annealing at 200 °C [ 13 ]. It is believed that the direct bonding of the Au/Ti films can contribute to a simple MEMS packaging process in which a wafer coated with the NEG film can form a seal and cause gettering, as illustrated in Figure 1 .…”

Section: Introductionmentioning

confidence: 99%

Wafer-Scale Room-Temperature Bonding of Smooth Au/Ti-Based Getter Layer for Vacuum Packaging

Matsumae

Kariya

Kurashima

et al. 2022

Sensors

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This study demonstrates room-temperature bonding using a getter layer for the vacuum packaging of microsystems. A thick Ti layer covered with an Au layer is utilized as a getter layer because it can absorb gas molecules in the package. Additionally, smooth Au surfaces can form direct bonds for hermetic sealing at room temperature. Direct bonding using a getter layer can simplify the vacuum packaging process; however, typical getter layers are rough in bonding formation. This study demonstrates two fabrication techniques for smooth getter layers. In the first approach, the Au/Ti layer is bonded to an Au layer on a smooth SiO2 template, and the Au/SiO2 interface is mechanically exfoliated. Although the root-mean-square roughness was reduced from 2.00 to 0.98 nm, the surface was still extremely rough for direct bonding. In the second approach, an Au/Ti/Au multilayer on a smooth SiO2 template is bonded with a packaging substrate, and the Au/SiO2 interface is exfoliated. The transferred Au/Ti/Au getter layer has a smooth surface with the root-mean-square roughness of 0.54 nm and could form wafer-scale direct bonding at room temperature. We believe that the second approach would allow a simple packaging process using direct bonding of the getter layer.

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“…Thus, the vacuum packaging process without encapsulation of getters is desirable. 17,18) Our previous study proposed a simple vacuum packaging process using the Au/Pt/Ti (from top to bottom) metal bonding layers. 19,20) It is reported that smooth Au surfaces can form hermetic sealing by atomic diffusion, even at room temperature under atmospheric conditions.…”

Section: Introductionmentioning

confidence: 99%

Simple and low-temperature vacuum packaging process by using Au/Ta/Ti metal multilayer

Kariya

Matsumae

Kurashima

et al. 2022

Jpn. J. Appl. Phys.

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A Au/Ta/Ti metal multilayer was developed to improve the high vacuum packaging process for microdevice fabrication. This study revealed that the wafer coated with the Au/Ta/Ti layer could form direct bonding and absorb residual gas. We investigated the effect of Ta layer thickness on the diffusion of Ti atoms. The Au/Ta/Ti metal multilayers were successfully bonded after a degassing process when the Ta barrier layer is thicker than 1.5 nm. Moreover, the Au/Ta/Ti metal film effectively absorbed the residual gas molecules by annealing at 350 °C. As the annealing temperature for the gas gettering is lower than the previous reports, the Au/Ta/Ti metal multilayer could be useful for the future vacuum packaging process.

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Application of thin Au/Ti double-layered films as both low-temperature bonding layer and residual gas gettering material for MEMS encapsulation

Cited by 12 publications

References 25 publications

Influence of Barrier Layers on ZrCoCe Getter Film Performance

Influence of Barrier Layers on ZrCoCe Getter Film Performance

Wafer-Scale Room-Temperature Bonding of Smooth Au/Ti-Based Getter Layer for Vacuum Packaging

Simple and low-temperature vacuum packaging process by using Au/Ta/Ti metal multilayer

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