We present experimental results of IC package decapsulation carried out using Ar and O2 gas mixture remote plasma generated by atmospheric microwave plasma needle (“a-MPN”). Depth etch rate of up to 6.5 µm/min and volume etch rate of up to 0.1 mm3/min were shown to be obtained by a-MPN process operated at 15 W microwave power. SEM imaging suggested no damage to the bonding wire, pads, or passivation.

Decap methods which have been used for copper wire packages are not effective for silver wire packages, and the authors recognized the need for the development of a novel method. This paper discusses the development of various processes to decap silver wire packages with acid. The first decap method developed for a silver wire package was to add hydrochloric acid to fuming nitric acid. This method proved insufficient to prevent silver wire from dissolving when solution temperature is 60 degree. The authors then developed the Saturation Etch method for decapsulating silver wire packages using a chemical solution. When dissolution amount of silver wire put in normal fuming HNO3 is defined as 100%, the authors were able to achieve its reduction to less than 3% by using saturated acid. This method is also effective for copper wire packages, and damages to wires can be minimized by dissolving copper into acid.