Reports, briefs and technical notes from Cools on semiconductor packaging technology and industry.
Technical noteThermal controlHybrid bonding heats an entire wafer for 0.5 to 4 hours to complete the Cu bond, even though the heat is needed only within a few micrometres of the interface. This technical note sets out an approach that transmits 1500 nm light through the silicon substrate and generates heat for nanoseconds only in an absorbing layer behind the Cu pad, together with the reasoning behind the design.
Technical noteBonding materialsAttempts to replace silver with copper in power semiconductor die attach go back a long way. What has blocked the switch is a copper oxide film a few nanometres thick. This technical note sets out an approach that addresses that barrier with a PDA functional layer combining reduction and oxidation resistance in a single surface layer, together with the supporting evidence.
Technical noteGlass substratesGlass package substrates and glass interposers differ in via size and wiring density but share the same manufacturing principle. This technical note covers the point at which moving to large areas changes the reliability requirement itself, and the trade-off in conventional TGV metallization that forced a choice between film continuity and access to the deep interior.