Date

2023-1-25

Author

Yurdakul, Özgün

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Electronic systems may be sealed by slicing the wafer into individual circuits and then packaging them or by packaging an integrated circuit while still part of the wafer. The latter enables the packaging of all detectors on complementary metal oxide semiconductors (CMOS) simultaneously, considerably decreasing manufacturing costs and increasing efficiency. Regarding a suitable packaging process for microbolometers, the most crucial parameter appears to be the compatibility of the packaging procedure with the detectors and the CMOS-based chips. Besides, as the MEMS's complexity and durability increase, more robust packaging is needed to achieve better packaging. For this purpose, in this study, a combinatorial approach that obtains multiple compositions for bonding purposes in a single deposition run was studied to investigate the best composition-property relation for MEMS packaging using binary Gold-Indium (Au-In) material system and Transient Liquid Phase (TLP) bonding method. In addition, a Gold – Indium – Tin (Au-In-Sn) ternary material system that has not been studied before in the literature for Wafer Level Packaging (WLP) has been studied to enhance the properties of the MEMS package. As a result of studies in this thesis, various compositions for the Au-In binary system were achieved with a combinatorial approach. According to comparing the results of characterization stages, the most efficient composition value was found for packaging MEMS devices with the Au-In TLP bonding method. Concerning that, almost %40 of the AuIn – AuIn2 intermetallic region has been investigated with only 3 In deposition run with a combinatorial approach. Furthermore, with single In deposition run via combinatorial deposition, up to 8% wt In composition range has been obtained. After combinatorial optimizations, 22 MPa average shear strength was achieved with 46.0 wt% In composition. Therefore, this thesis has studied optimizing the composition/property relationship with the combinatorial approach. Furthermore, after optimization of the composition of the In in Au-In binary system, WLP was done with a cap cavity to observe of hermetic properties of the structure. 8 µm cap deflection depth has been achieved with 24 µm membrane thickness, providing 0.2 mbar pressure inside the package without any gas penetration. Moreover, with an optimized composition value, 28 MPa package strength was observed in that sample. Although Au-In-Sn ternary bonding system seems to be one of the candidate materials systems for WLP packaging of MEMS since TLP bonding conditions have been obtained according to Differential Scanning Calorimetry results, higher than 49 MPa shear strength was achieved and high bond integrity has been acquired concerning Scanning Acoustic Microscope inspection, this system requires re-evaluation for use as a result of the low yield of successfully packaged chips after bonding experiments.

Subject Keywords

Wafer-level packaging, Combinatorial approach, Au-In alloy, Transient liquid phase bonding, MEMS packaging

URI

https://hdl.handle.net/11511/102568

Collections

Graduate School of Natural and Applied Sciences, Thesis