{"id":{"repo_id":"tu-berlin","oai_identifier":"oai:depositonce.tu-berlin.de:11303/26271"},"canonical_url":"https://search.dev.ndltd.org/etd/tu-berlin/oai:depositonce.tu-berlin.de:11303/26271","repository":{"repo_id":"tu-berlin","name":"Technische Universität Berlin","base_url":"https://api-depositonce.tu-berlin.de/server/oai/request"},"display":{"title":"Degradation modes of the top-side contacting of SiC power semiconductors","abstract":"This dissertation investigates the reliability of assembly and interconnection technologies in silicon carbide power modules, specifically focusing on top-side interconnections using aluminum and copper bond wires. Driven by the increasing demand for robust and high-performance silicon carbide modules for applications in electric mobility and power electronics requiring high power densities, switching frequencies, and operating temperatures, two module types—aluminum modules (aluminum bond wires, aluminum metallization) and copper modules (copper bond wires, copper metallization)—were designed, fabricated, and tested using active power cycling. Modules were subjected to varying temperature cycles (110 - 170 Kelvin) under two environmental conditions: uncapped and nitrogen flooded, to assess the impact of oxidation on reliability. Experimental lifetime data were compared with established lifetime models (CIPS 08, SKiM 63) and literature data. Finite element method simulations complemented the experimental analysis to investigate stress and strain distribution in the bond interconnections and to better understand degradation mechanisms. In the Al module, thermomechanical stresses led to bond wire lift-off, with cracks starting at the bond foot and spreading along the bond interface due to the coefficient of thermal expansion (CTE) mismatch between aluminum and SiC. Microscopic analyses showed recrystallization and grain coarsening, which weakened the material strength. In the Cu modules, the increase in thermal resistance led to the degradation of the Ag-sinter die-attach connection. Oxidation in non-encapsulated modules promoted brittle crack formation, while nitrogen-flooded modules exhibited longer lifetimes. Oxidation in non-encapsulated Cu modules caused brittle, vertical cracks in the Cu metallization, extending close to the SiC semiconductor structures. Compared to the Al module, this is a new failure mechanism. In nitrogen-flooded Cu modules with minimal oxidation, a horizontal crack formed below the bond interface in the Cu metallization. Prolonged APC stress may lead to delamination of the metallization from the bond, which also degrades heat dissipation and represents a failure mechanism similar to that observed in the Al module. Finite element method simulations corroborated the experimental findings, showing that the highest plastic strains occur in the aluminum bond feet and the copper bond wire foot near the metallization interface. For both aluminum and copper, thinner bond wires and thicker metallizations resulted in reduced plastic strain and thus increased lifetime. The simulations underscore the importance of optimized assembly and interconnection technologies design, particularly metallization thickness, for the reliability of silicon carbide power modules. This work elucidates the influence of material, oxidation, and metallization thickness on the lifetime of bond interconnections in silicon carbide power modules, providing insights for the development of highly reliable assembly and interconnection technologies concepts. Copper proves to be a promising bond wire material for silicon carbide chips. Future research should focus on optimizing copper metallization, the influence of encapsulation materials, investigating the impact of aging and humidity under realistic operating conditions, and refining simulation models to improve lifetime predictions and understanding of the complex failure mechanisms.","abstract_html":"This dissertation investigates the reliability of assembly and interconnection technologies in silicon carbide power modules, specifically focusing on top-side interconnections using aluminum and copper bond wires. Driven by the increasing demand for robust and high-performance silicon carbide modules for applications in electric mobility and power electronics requiring high power densities, switching frequencies, and operating temperatures, two module types—aluminum modules (aluminum bond wires, aluminum metallization) and copper modules (copper bond wires, copper metallization)—were designed, fabricated, and tested using active power cycling. Modules were subjected to varying temperature cycles (110 - 170 Kelvin) under two environmental conditions: uncapped and nitrogen flooded, to assess the impact of oxidation on reliability. Experimental lifetime data were compared with established lifetime models (CIPS 08, SKiM 63) and literature data. Finite element method simulations complemented the experimental analysis to investigate stress and strain distribution in the bond interconnections and to better understand degradation mechanisms. In the Al module, thermomechanical stresses led to bond wire lift-off, with cracks starting at the bond foot and spreading along the bond interface due to the coefficient of thermal expansion (CTE) mismatch between aluminum and SiC. Microscopic analyses showed recrystallization and grain coarsening, which weakened the material strength. In the Cu modules, the increase in thermal resistance led to the degradation of the Ag-sinter die-attach connection. Oxidation in non-encapsulated modules promoted brittle crack formation, while nitrogen-flooded modules exhibited longer lifetimes. Oxidation in non-encapsulated Cu modules caused brittle, vertical cracks in the Cu metallization, extending close to the SiC semiconductor structures. Compared to the Al module, this is a new failure mechanism. In nitrogen-flooded Cu modules with minimal oxidation, a horizontal crack formed below the bond interface in the Cu metallization. Prolonged APC stress may lead to delamination of the metallization from the bond, which also degrades heat dissipation and represents a failure mechanism similar to that observed in the Al module. Finite element method simulations corroborated the experimental findings, showing that the highest plastic strains occur in the aluminum bond feet and the copper bond wire foot near the metallization interface. For both aluminum and copper, thinner bond wires and thicker metallizations resulted in reduced plastic strain and thus increased lifetime. The simulations underscore the importance of optimized assembly and interconnection technologies design, particularly metallization thickness, for the reliability of silicon carbide power modules. This work elucidates the influence of material, oxidation, and metallization thickness on the lifetime of bond interconnections in silicon carbide power modules, providing insights for the development of highly reliable assembly and interconnection technologies concepts. Copper proves to be a promising bond wire material for silicon carbide chips. Future research should focus on optimizing copper metallization, the influence of encapsulation materials, investigating the impact of aging and humidity under realistic operating conditions, and refining simulation models to improve lifetime predictions and understanding of the complex failure mechanisms.","abstract_has_math":false,"creators":["Sankari, Rasched"],"institution":null,"degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2025,"date_issued":"2025","date_published":"2025","updated_at":"2026-07-27T21:28:37Z","subjects":[],"languages":["en"],"rights":[],"rights_urls":["https://creativecommons.org/licenses/by/4.0/"],"identifier_entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://doi.org/10.14279/depositonce-25099"],"render_values":[{"text":"https://doi.org/10.14279/depositonce-25099","href":"https://doi.org/10.14279/depositonce-25099","code":true}]}]},"links":{"outbound_url":"https://depositonce.tu-berlin.de/handle/11303/26271","outbound_label":"Repository record","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Sankari, Rasched"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2026-03-17T14:52:36Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2026-03-17T14:52:36Z"]},{"key":"dc:date.issued","label":"Date","values":["2025"]},{"key":"dc:type","label":"Dc Type","values":["Doctoral Thesis"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en"]},{"key":"dc:rights.uri","label":"Rights URI","values":["https://creativecommons.org/licenses/by/4.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://depositonce.tu-berlin.de/handle/11303/26271","https://doi.org/10.14279/depositonce-25099"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Is version of: Sankari, R. (2025): Degradationsmodi der Oberseitenkontaktierung von SiC-Leistungshalbleitern. Technische Universität Berlin. DOI: 10.14279/depositonce-24576"]},{"key":"dc:description.abstract","label":"Abstract","values":["This dissertation investigates the reliability of assembly and interconnection technologies in silicon carbide power modules, specifically focusing on top-side interconnections using aluminum and copper bond wires. Driven by the increasing demand for robust and high-performance silicon carbide modules for applications in electric mobility and power electronics requiring high power densities, switching frequencies, and operating temperatures, two module types—aluminum modules (aluminum bond wires, aluminum metallization) and copper modules (copper bond wires, copper metallization)—were designed, fabricated, and tested using active power cycling. Modules were subjected to varying temperature cycles (110 - 170 Kelvin) under two environmental conditions: uncapped and nitrogen flooded, to assess the impact of oxidation on reliability. Experimental lifetime data were compared with established lifetime models (CIPS 08, SKiM 63) and literature data. Finite element method simulations complemented the experimental analysis to investigate stress and strain distribution in the bond interconnections and to better understand degradation mechanisms. In the Al module, thermomechanical stresses led to bond wire lift-off, with cracks starting at the bond foot and spreading along the bond interface due to the coefficient of thermal expansion (CTE) mismatch between aluminum and SiC. Microscopic analyses showed recrystallization and grain coarsening, which weakened the material strength. In the Cu modules, the increase in thermal resistance led to the degradation of the Ag-sinter die-attach connection. Oxidation in non-encapsulated modules promoted brittle crack formation, while nitrogen-flooded modules exhibited longer lifetimes. Oxidation in non-encapsulated Cu modules caused brittle, vertical cracks in the Cu metallization, extending close to the SiC semiconductor structures. Compared to the Al module, this is a new failure mechanism. In nitrogen-flooded Cu modules with minimal oxidation, a horizontal crack formed below the bond interface in the Cu metallization. Prolonged APC stress may lead to delamination of the metallization from the bond, which also degrades heat dissipation and represents a failure mechanism similar to that observed in the Al module. Finite element method simulations corroborated the experimental findings, showing that the highest plastic strains occur in the aluminum bond feet and the copper bond wire foot near the metallization interface. For both aluminum and copper, thinner bond wires and thicker metallizations resulted in reduced plastic strain and thus increased lifetime. The simulations underscore the importance of optimized assembly and interconnection technologies design, particularly metallization thickness, for the reliability of silicon carbide power modules. This work elucidates the influence of material, oxidation, and metallization thickness on the lifetime of bond interconnections in silicon carbide power modules, providing insights for the development of highly reliable assembly and interconnection technologies concepts. Copper proves to be a promising bond wire material for silicon carbide chips. Future research should focus on optimizing copper metallization, the influence of encapsulation materials, investigating the impact of aging and humidity under realistic operating conditions, and refining simulation models to improve lifetime predictions and understanding of the complex failure mechanisms.","Diese Dissertation untersucht die Zuverlässigkeit von Aufbau- und Verbindungstechniken in Siliziumkarbid (SiC)-Leistungsmodulen, insbesondere die Oberseitenkontaktierung mit Aluminium- und Kupfer-Bonddrähten. Motiviert durch den steigenden Bedarf an robusten und leistungsfähigen SiC-Modulen für Anwendungen in der Elektromobilität und Leistungselektronik, die hohe Leistungsdichten, Schaltfrequenzen und Betriebstemperaturen erfordern, wurden zwei Modultypen konzipiert, aufgebaut und mit Hilfe von Active Power Cycling erprobt: ein Aluminium-Modul (Aluminium-Bonddrähte, Aluminium-Metallisierung des SiC-Halbleiters) und ein Kupfer-Modul (Kupfer-Bonddrähte, Kupfer-Metallisierung des SiC-Halbleiters). Die Module wurden unter variierenden Temperaturhüben (110 - 170 K) und zwei unterschiedlichen Umgebungsbedingungen – unverkapselt oder mit Stickstoff geflutet – getestet, um den Einfluss der Oxidation auf die Zuverlässigkeit zu untersuchen. Die experimentell ermittelten Lebensdauerdaten wurden mit etablierten Lebensdauermodellen (CIPS 08, SKiM 63) und Literaturdaten verglichen. Finite-Elemente-Simulationen ergänzten die experimentelle Analyse, um die Spannungs- und Dehnungsverteilung in den Bondverbindungen zu untersuchen und die Degradationsmechanismen besser zu verstehen. Beim Al-Modul führten thermomechanische Spannungen zum Bonddraht-Lift-off, wobei Risse am Bondfuß begannen und sich entlang des Bondinterfaces ausbreiteten, aufgrund des Wärmeausdehnungskoeffizienten (CTE)-Mismatchs zwischen Aluminium und SiC. Mikroskopische Analysen zeigten Rekristallisation und Kornvergröberung, die die Materialfestigkeit schwächten. Bei den Cu-Modulen führte der Anstieg des thermischen Widerstands zur Degradation der Ag-Sinter-Die-Attach-Verbindung. Oxidation in unverkapselten Modulen förderte spröde Rissbildung, während stickstoffgeflutete Module eine längere Lebensdauer aufwiesen. Oxidation in unverkapselten Cu-Modulen verursachte spröde, vertikale Risse in der Cu-Metallisierung, die sich bis in die Nähe der SiC-Halbleiterstrukturen erstreckten. Im Vergleich zum Al-Modul ist dies ein neuer Versagensmechanismus. Bei stickstoffgefluteten Cu-Modulen mit minimaler Oxidation bildete sich ein horizontaler Riss unterhalb des Bondinterfaces in der Cu-Metallisierung. Längere APC-Belastung könnte zur Delamination der Metallisierung mit Bond führen, was ebenfalls die Wärmeableitung verschlechtert und einen ähnlichen Versagensmechanismus wie beim Al-Modul darstellt. Die Finite-Elemente-Simulationen bestätigten die experimentellen Befunde und zeigten, dass die höchsten plastischen Dehnungen in den Al-Bondfüßen bzw. im Cu-Bonddrahtfuß nahe der Grenzfläche zur Metallisierung auftreten. Sowohl bei Aluminium als auch bei Kupfer führen dünnere Bonddrähte und dickere Metallisierungen zu reduzierten plastischen Dehnungen und somit zu einer gesteigerten Lebensdauer. Die Simulationen unterstreichen die Bedeutung einer optimierten Aufbau- und Verbindungstechnik-Gestaltung, insbesondere der Metallisierungsdicke, für die Zuverlässigkeit von SiC-Leistungsmodulen. Die Ergebnisse dieser Arbeit verdeutlichen den Einfluss von Material, Oxidation und Metallisierungsdicke auf die Lebensdauer von Bondverbindungen in SiC-Leistungsmodulen und liefern Erkenntnisse für die Entwicklung hochzuverlässiger Aufbau- und Verbindungstechnik-Konzepte. Kupfer erweist sich als vielversprechendes Bonddrahtmaterial für SiC-Chips. Zukünftige Forschung sollte die Optimierung der Kupfer-Metallisierung, den Einfluss der Verkapselungsmaterialien, die Untersuchung des Einflusses von Alterung und Feuchte unter produktnahen Betriebsbedingungen sowie die Verfeinerung der Simulationsmodelle fokussieren, um die Lebensdauerprognosen zu verbessern und das Verständnis der komplexen Ausfallmechanismen zu vertiefen."]},{"key":"dc:title","label":"Title","values":["Degradation modes of the top-side contacting of SiC power semiconductors"]}]}],"canonical_facts":{"dc:creator":["Sankari, Rasched"],"dc:date.accessioned":["2026-03-17T14:52:36Z"],"dc:date.available":["2026-03-17T14:52:36Z"],"dc:date.issued":["2025"],"dc:description":["Is version of: Sankari, R. (2025): Degradationsmodi der Oberseitenkontaktierung von SiC-Leistungshalbleitern. Technische Universität Berlin. DOI: 10.14279/depositonce-24576"],"dc:description.abstract":["This dissertation investigates the reliability of assembly and interconnection technologies in silicon carbide power modules, specifically focusing on top-side interconnections using aluminum and copper bond wires. Driven by the increasing demand for robust and high-performance silicon carbide modules for applications in electric mobility and power electronics requiring high power densities, switching frequencies, and operating temperatures, two module types—aluminum modules (aluminum bond wires, aluminum metallization) and copper modules (copper bond wires, copper metallization)—were designed, fabricated, and tested using active power cycling. Modules were subjected to varying temperature cycles (110 - 170 Kelvin) under two environmental conditions: uncapped and nitrogen flooded, to assess the impact of oxidation on reliability. Experimental lifetime data were compared with established lifetime models (CIPS 08, SKiM 63) and literature data. Finite element method simulations complemented the experimental analysis to investigate stress and strain distribution in the bond interconnections and to better understand degradation mechanisms. In the Al module, thermomechanical stresses led to bond wire lift-off, with cracks starting at the bond foot and spreading along the bond interface due to the coefficient of thermal expansion (CTE) mismatch between aluminum and SiC. Microscopic analyses showed recrystallization and grain coarsening, which weakened the material strength. In the Cu modules, the increase in thermal resistance led to the degradation of the Ag-sinter die-attach connection. Oxidation in non-encapsulated modules promoted brittle crack formation, while nitrogen-flooded modules exhibited longer lifetimes. Oxidation in non-encapsulated Cu modules caused brittle, vertical cracks in the Cu metallization, extending close to the SiC semiconductor structures. Compared to the Al module, this is a new failure mechanism. In nitrogen-flooded Cu modules with minimal oxidation, a horizontal crack formed below the bond interface in the Cu metallization. Prolonged APC stress may lead to delamination of the metallization from the bond, which also degrades heat dissipation and represents a failure mechanism similar to that observed in the Al module. Finite element method simulations corroborated the experimental findings, showing that the highest plastic strains occur in the aluminum bond feet and the copper bond wire foot near the metallization interface. For both aluminum and copper, thinner bond wires and thicker metallizations resulted in reduced plastic strain and thus increased lifetime. The simulations underscore the importance of optimized assembly and interconnection technologies design, particularly metallization thickness, for the reliability of silicon carbide power modules. This work elucidates the influence of material, oxidation, and metallization thickness on the lifetime of bond interconnections in silicon carbide power modules, providing insights for the development of highly reliable assembly and interconnection technologies concepts. Copper proves to be a promising bond wire material for silicon carbide chips. Future research should focus on optimizing copper metallization, the influence of encapsulation materials, investigating the impact of aging and humidity under realistic operating conditions, and refining simulation models to improve lifetime predictions and understanding of the complex failure mechanisms.","Diese Dissertation untersucht die Zuverlässigkeit von Aufbau- und Verbindungstechniken in Siliziumkarbid (SiC)-Leistungsmodulen, insbesondere die Oberseitenkontaktierung mit Aluminium- und Kupfer-Bonddrähten. Motiviert durch den steigenden Bedarf an robusten und leistungsfähigen SiC-Modulen für Anwendungen in der Elektromobilität und Leistungselektronik, die hohe Leistungsdichten, Schaltfrequenzen und Betriebstemperaturen erfordern, wurden zwei Modultypen konzipiert, aufgebaut und mit Hilfe von Active Power Cycling erprobt: ein Aluminium-Modul (Aluminium-Bonddrähte, Aluminium-Metallisierung des SiC-Halbleiters) und ein Kupfer-Modul (Kupfer-Bonddrähte, Kupfer-Metallisierung des SiC-Halbleiters). Die Module wurden unter variierenden Temperaturhüben (110 - 170 K) und zwei unterschiedlichen Umgebungsbedingungen – unverkapselt oder mit Stickstoff geflutet – getestet, um den Einfluss der Oxidation auf die Zuverlässigkeit zu untersuchen. Die experimentell ermittelten Lebensdauerdaten wurden mit etablierten Lebensdauermodellen (CIPS 08, SKiM 63) und Literaturdaten verglichen. Finite-Elemente-Simulationen ergänzten die experimentelle Analyse, um die Spannungs- und Dehnungsverteilung in den Bondverbindungen zu untersuchen und die Degradationsmechanismen besser zu verstehen. Beim Al-Modul führten thermomechanische Spannungen zum Bonddraht-Lift-off, wobei Risse am Bondfuß begannen und sich entlang des Bondinterfaces ausbreiteten, aufgrund des Wärmeausdehnungskoeffizienten (CTE)-Mismatchs zwischen Aluminium und SiC. Mikroskopische Analysen zeigten Rekristallisation und Kornvergröberung, die die Materialfestigkeit schwächten. Bei den Cu-Modulen führte der Anstieg des thermischen Widerstands zur Degradation der Ag-Sinter-Die-Attach-Verbindung. Oxidation in unverkapselten Modulen förderte spröde Rissbildung, während stickstoffgeflutete Module eine längere Lebensdauer aufwiesen. Oxidation in unverkapselten Cu-Modulen verursachte spröde, vertikale Risse in der Cu-Metallisierung, die sich bis in die Nähe der SiC-Halbleiterstrukturen erstreckten. Im Vergleich zum Al-Modul ist dies ein neuer Versagensmechanismus. Bei stickstoffgefluteten Cu-Modulen mit minimaler Oxidation bildete sich ein horizontaler Riss unterhalb des Bondinterfaces in der Cu-Metallisierung. Längere APC-Belastung könnte zur Delamination der Metallisierung mit Bond führen, was ebenfalls die Wärmeableitung verschlechtert und einen ähnlichen Versagensmechanismus wie beim Al-Modul darstellt. Die Finite-Elemente-Simulationen bestätigten die experimentellen Befunde und zeigten, dass die höchsten plastischen Dehnungen in den Al-Bondfüßen bzw. im Cu-Bonddrahtfuß nahe der Grenzfläche zur Metallisierung auftreten. Sowohl bei Aluminium als auch bei Kupfer führen dünnere Bonddrähte und dickere Metallisierungen zu reduzierten plastischen Dehnungen und somit zu einer gesteigerten Lebensdauer. Die Simulationen unterstreichen die Bedeutung einer optimierten Aufbau- und Verbindungstechnik-Gestaltung, insbesondere der Metallisierungsdicke, für die Zuverlässigkeit von SiC-Leistungsmodulen. Die Ergebnisse dieser Arbeit verdeutlichen den Einfluss von Material, Oxidation und Metallisierungsdicke auf die Lebensdauer von Bondverbindungen in SiC-Leistungsmodulen und liefern Erkenntnisse für die Entwicklung hochzuverlässiger Aufbau- und Verbindungstechnik-Konzepte. Kupfer erweist sich als vielversprechendes Bonddrahtmaterial für SiC-Chips. Zukünftige Forschung sollte die Optimierung der Kupfer-Metallisierung, den Einfluss der Verkapselungsmaterialien, die Untersuchung des Einflusses von Alterung und Feuchte unter produktnahen Betriebsbedingungen sowie die Verfeinerung der Simulationsmodelle fokussieren, um die Lebensdauerprognosen zu verbessern und das Verständnis der komplexen Ausfallmechanismen zu vertiefen."],"dc:identifier.uri":["https://depositonce.tu-berlin.de/handle/11303/26271","https://doi.org/10.14279/depositonce-25099"],"dc:language.iso":["en"],"dc:rights.uri":["https://creativecommons.org/licenses/by/4.0/"],"dc:title":["Degradation modes of the top-side contacting of SiC power semiconductors"],"dc:type":["Doctoral Thesis"]},"updated_at":"2026-07-27T21:28:37Z"}