Three-Dimensional Integration of Power Electronic Devices Using Wafer Level Deposited Copper Sinter Paste
Publikationen: Thesis / Studienabschlussarbeiten und Habilitationsschriften › Masterarbeit
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Publikationen: Thesis / Studienabschlussarbeiten und Habilitationsschriften › Masterarbeit
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TY - THES
T1 - Three-Dimensional Integration of Power Electronic Devices Using Wafer Level Deposited Copper Sinter Paste
AU - Karner, Stefan
N1 - embargoed until 30-06-2020
PY - 2019
Y1 - 2019
N2 - Bond materials are presently intensively investigated for the production of cost-efficient, lead-free, highly conductive and highly reliable interconnections between high power semiconductor devices. In general, pure Cu interconnects, which are fabricated by paste sintering, match these demands and have been further shown to surpass other interconnect technologies regarding cost efficiency, electromigration resistance and high-temperature reliability. In the course of this master thesis, thermal compression and thermosonic bonding were investigated for the three dimensional integration of power electronic devices. Furthermore, wafer level deposited copper (Cu) sinter paste was employed as bonding material, which permits a low-ohmic contact among the stacked devices. A systematic design of experiments (DoE) was conducted to evaluate a mild parameter setup for thermal compression bonding of two power devices. In more detail, the pressureless curing temperature, bonding specifications and an optional post-bond annealing step were considered as parameters within this DoE. The resulting sinter joints were investigated with regards to their morphology, interfacial adhesion and mechanical strength by conducting scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), scanning acoustic microscopy (SAM) and shear test measurements. Moreover, linear regression analysis was conducted to investigate the influence of each parameter on the mechanical quality of the sinter joint in more detail. A feasibility study of thermosonic bonding for the vertical integration of semiconductor devices was additionally performed on dummy chips, with the aim of achieving lower temperature and pressure specifications in comparison to thermal compression bonding. In summary, it was shown that an electrically working interconnect with sufficiently good mechanical properties can be manufactured by thermal compression bonding with temperatures and pressures below 400 °C and 50 MPa. The introduction of ultrasonic energy during bonding additionally shifted the bonding parameters to significantly lower values.
AB - Bond materials are presently intensively investigated for the production of cost-efficient, lead-free, highly conductive and highly reliable interconnections between high power semiconductor devices. In general, pure Cu interconnects, which are fabricated by paste sintering, match these demands and have been further shown to surpass other interconnect technologies regarding cost efficiency, electromigration resistance and high-temperature reliability. In the course of this master thesis, thermal compression and thermosonic bonding were investigated for the three dimensional integration of power electronic devices. Furthermore, wafer level deposited copper (Cu) sinter paste was employed as bonding material, which permits a low-ohmic contact among the stacked devices. A systematic design of experiments (DoE) was conducted to evaluate a mild parameter setup for thermal compression bonding of two power devices. In more detail, the pressureless curing temperature, bonding specifications and an optional post-bond annealing step were considered as parameters within this DoE. The resulting sinter joints were investigated with regards to their morphology, interfacial adhesion and mechanical strength by conducting scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), scanning acoustic microscopy (SAM) and shear test measurements. Moreover, linear regression analysis was conducted to investigate the influence of each parameter on the mechanical quality of the sinter joint in more detail. A feasibility study of thermosonic bonding for the vertical integration of semiconductor devices was additionally performed on dummy chips, with the aim of achieving lower temperature and pressure specifications in comparison to thermal compression bonding. In summary, it was shown that an electrically working interconnect with sufficiently good mechanical properties can be manufactured by thermal compression bonding with temperatures and pressures below 400 °C and 50 MPa. The introduction of ultrasonic energy during bonding additionally shifted the bonding parameters to significantly lower values.
KW - 3D integration
KW - vertical integration
KW - power semiconductor
KW - thermal compression bonding
KW - thermosonic bonding
KW - copper
KW - sinter paste
KW - stencil printing
KW - wafer level
KW - 3D Integration
KW - vertikale Integration
KW - Leistungshalbleiter
KW - Thermokompressionsbonden
KW - Thermosonicbonden
KW - Kupfer
KW - Sinterpaste
KW - Schablonendruck
KW - Waferebene
M3 - Master's Thesis
ER -