A novel scanned mask imaging system for high resolution solid state laser ablation

Abstract

A technology gap has emerged between the sub-micron semiconductor manufacturing technologies used in the manufacture of integrated circuits and the semi-additive processes used to manufacture advanced chip packages which are currently limited to feature sizes greater than 10 µm. Embedding conductors in laser ablated circuit features is one of the proposed solutions to address this technology gap in the advanced chip packaging industry. Excimer laser systems are currently the only available production tools capable of the high throughput laser ablation of circuit features down to 2 µm. In this thesis I have developed an ablative, solid state laser, mask imaging system for the high volume 3D structuring of organic dielectrics. This system enables the ablation of circuit features down to 2 µm which are of comparable quality to excimer laser ablation. The system architecture has a throughput exceeding that of an excimer laser production system. I have developed an illumination system, which I have tested at both a feasibility stage and at a prototype stage, with custom designed optical components. The illumination system consists of a galvanometer scan head which is used to raster scan a solid state laser beam across a binary mask, the image of which is then projected onto the substrate. The system I present enables the use of multimode, UV, solid state lasers in well-developed and high resolution mask imaging optical systems. Through the use of a less expensive laser technology, the system I have developed has a cost of ownership estimated to be less than 50% of that of an excimer production system, thus reducing the cost of high resolution, high throughput laser ablation.