The 20th Annual Device Packaging Conference (DPC), Arizona

From March 18 to 21, 2024, the Annual Device Packaging Conference (DPC) will take place in Fountain Hills, Arizona. The event is organized by the International Microelectronics Assembly and Packaging Society (IMAPS).

On March 20, starting at 2 pm, Prof. Dr. Tsvetina Dobrovolska, D.Sc. will give a presentation in the session "WP2: Fan-Out, Wafer Level Packaging & Flip Chip Track: Process and Materials":

Annealing Behavior of Electroplated  Nanograined Copper

Copper bonding (direct and hybrid) in interconnection – one of these concepts, will benefit from an electroplated nanograined copper. The copper grain size for this purpose should not change for up to 1 month at RT, but increases up to 10 times under bonding conditions.  It is desirable that the electroplated copper has low impurities and achieves strong Cu2Cu bonds at low temperatures without voids.

The electrodeposition of nanograined copper with IntraCu® SC-4 electrolyte was investigated with voltammetry, SEM, EBSD, GDEOS and SIMS methods. The effect of current density, grain size of seed layer and geometry of vias on the structure of nanograined copper was   established. The resulting coatings were characterized for: 

Grain size (less than 150nm) stability at room temperature storage  - unchangeable more than 3 weeks (almost suppressed self-annealing behavior);
Increasing  of the size of copper grains  after different annealing temperature and duration – from 120⁰ to the 260⁰ C, from 1 to 10 hours, also with different annealing profile. Size of grains is shown to increase more than 7 times-10, even at lower than 200⁰ C temperature
A linear relationship between the impurities, voids in the layer and the concentration of additives (as well  current density)  was found. According to this relation, the size, stability in time, impurities and annealing behavior of the nanocrystals could be predicted and controlled.

Further information about the event can be found on the conference website.