TGV Microfabrication Technology for 3D Packaging

Glass is expected to be applied to a core material for panel size interposer for 3D package system nowadays. The most important challenge for glass as an interposer is the development of through hole formation with cost-effective and high-throughput. Several through hole drilling technologies such as wet etching, deep reactive-ion etching, sandblasting, laser ablation and the use of photosensitive glass have been studied and reported so far. However, the glass microfabrication technology combining both high-throughput and large area processability have not been reported yet. This study explored the new glass fabrication method by means of electrical discharge to realize high throughput and fine pitch hole drilling. An alkali-free glass substrate was used. Focused and controlled electrical discharge induced dielectric breakdown of glass material and also created Joule heat induced ablation and ejection of glass. Approximately 50 – 60 micron in diameter through hole was made. The result shows, even serial process can have a potential for high high-throughput solution, because this phenomenon can complete as an ultrashort process time of 1msec or less. In terms of fine pitch processability, 100um pitch hole drilling was confirmed. In this study, several glass fabrication technologies were compared by SEM and optical microscope observation for hole shape characteristic. Additionally a potential of industrialization and fine pitch hole drilling were considered. This study pointed out necessary development subjects towards an application, glass core material for 3D interposer substrate.