Fast Etching of Molding Compound by an Ar/O2/CF4 Plasma and Process Improvements for Semiconductor Package Decapsulation

Abstract

Decapsulation of a SOT23 semiconductor package with 23 um copper wire bonds is conducted with an especially designed microwave induced plasma system. It is found that a 30%-60% CF4 addition in the O2/CF4 etchant gas results in high molding compound etching rate. Si3N4 overetching which is encountered in plasma decapsulation is solved by an improved etching process. Critical processing parameters are investigated and 350 um thick molding compound on top of the die is removed selectively by pure plasma etching for 6 minutes, which is at least 10 times faster than conventional plasma etchers.