Photosensitive polymer reliability for fine pitch RDL applications

We present the reliability results obtained on a two-metal level copper RDL patterned on a photosensitive polymer with a target pitch below 4 μm. Our polymer has been submitted to high temperature storage at 150 °C and to temperature humidity stress at 85 °C/85 %RH for 1000 hours. A thermal cycling...

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Bibliographic Details
Main Authors: Chery, Emmanuel, Duval, Fabrice F. C., Stucchi, Michele, Slabbekoorn, John, Croes, Kristof, Beyne, Eric
Format: Conference Proceeding
Language:English
Subjects:
3D packaging
Copper
Corrosion
Fine pitch RDL
high temperature storage
High-temperature superconductors
Moisture
photosensitive polymer
Polymers
reliability
Stress
thermal cycling
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Summary:We present the reliability results obtained on a two-metal level copper RDL patterned on a photosensitive polymer with a target pitch below 4 μm. Our polymer has been submitted to high temperature storage at 150 °C and to temperature humidity stress at 85 °C/85 %RH for 1000 hours. A thermal cycling stress between -50 °C and 125 °C for 1000 cycles was also performed on these samples.Collected electrical data indicate an increase in the copper wires resistivity and via resistance after 1000 hours at 150 °C. Failure analyses performed on the stressed samples reveal the formation of a copper oxide layer on top of the metal lines and at the bottom of the vias resulting from the presence of water at the interface metal/polymer. The presence of moisture inside the polymer is further confirmed by Fourier-transform infrared spectroscopy (FTIR) measurements. These results emphasize the need of a capping layer on top of the metal lines and reiterate the need of a continuous Ti barrier for a reliable process.
ISSN:2377-5726
DOI:10.1109/ECTC32862.2020.00197