X-ray photoelectron spectroscopy, depth profiling, and elemental imaging of metal/polyimide interfaces of high density interconnecct packages subjected to temperature and humidity

摘要

X-ray photoelectron spectroscopy was used to analyze surfaces adn buried interfaces of a tape ball grid array interconnect packate that was exposed to temperature and humidity lesting. Two metallization structures, employing 3.5 and 7.5nm Cr adhesion layers, respectively, showed dramatically different results in the PCT. For the metallization with 3.5nm Cr, spontaneous failre occurred on the polymer side of jthe metal/polyimide inerface. Copper and other metals were detected by XPS on and below this polymer surface. For the metallization with 7.5nm Cr, which did not delaminate in the PCT, the metallization was manually peeled away and also showed failure at the polymer side of the interface. Conventional XPS taken from a 1 mm diameter area showed the presence of metals on and below this polymer surface. Detailed spatially-resolved analysis using small area XPS and imaging XPS showed that this metal did not migrate through and below the metal/poly mer interface, but around and outside of jthe metallized area.