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Presentation Hall ICM - Internationales Congress Center München SEMICON EUROPA > Strategic Materials Conference > Session 3 - Power
09:10-09:40 h | ICM - Internationales Congress Center München ICM Room 13a, 1st Floor
Subjects: SEMICON EUROPA
Copper metallization is widely used in More than Moore applications for interconnects. Through silicon vias (TSV), copper pillars and redistribution layers are used for chip stacking or in system in package applications. Thick copper metallization for power devices increases the performance of smart power devices or MOSFETs. For all these applications, copper is mainly deposited by electroplating. The advantage of electroplating is that the growth mechanism of the copper film can be tailored for each application by adding the right organic additives to the electrolyte.In this paper, we present how different additive packages influence the solderability and the mechanical properties of the deposited Cu films. Using additive package A (electrolyte A, film A) a more conformal deposition at high deposition rates is achieved compared to additive package B (electrolyte B, film B). However, films deposited with electrolyte A show increased incorporation of sulfur and chlorine compared to electrolyte B. This indicates that more additives are incorporated into films deposited with electrolyte A. This contamination lowers the interface energy between Cu and SnAg balls  for flip chip or Cu pillar applications and therefore more voids are induced at the Cu-SnAg interface after thermal storage compared to electrolyte B.The mechanical properties of Cu films A and B were determined by micro tension tests of freestanding Cu films. The test equipment is heatable and was installed into a SEM to visualize the fracture mechanism . Whereas Cu films A show very small grains after annealing the grains of film B are in the order of the sample geometry. Cu films A show therefore a higher yield stress compared to films B at room temperature; however the fracture mechanism changes with increasing temperature to brittle for film A as a result of segregation of sulfur and chlorine to the grain boundaries .
Infineon Technologies AG
Werner Robl received his PhD in Physics from the University of Regensburg in 1994. After his degree he joined Infineon (former Siemens Semiconductors). Since then he has been working on development of new metallization schemes in Regensburg and Munich, Germany and East Fishkill, USA. Currently he is working as senior principal on new metallization schemes for semiconductors.