Recent advances in laser assisted polymer intermediate layer bonding for MEMS packaging

This paper presents the recent advances in the development of a laser assisted fast polymer bonding method for electronic packaging applications. In this method a high power diode laser is used to cure a polymer adhesive material to bond substrates together. A unique beam forming method using custom designed optical phase plate elements was developed to transform a fiber delivered laser beam into top-hat and frame shaped beam profiles for energy efficient polymer bonding for electronics manufacturing. In addition it has been found that the frame shaped beam profile can produce a desirable temperature distribution for MEMS packaging in which the surface temperature at the center of the substrate is lower by ~50degC than the packaging temperature (~300degC) when bonding a glass cap to a silicon substrate. An accurate temperature monitoring method using an embedded thin film microsensor array has been developed and has been used successfully for process monitoring. Defect-free fast bonding (~10 seconds) of transparent cap (glass) and non-transparent cap (silicon) to a silicon chip has been demonstrated. This work illustrates the potential of the diode laser based photonic technology for advanced MEMS packaging and electronics manufacturing.