Bringing New Life To Glass For Wafer-Level Packaging Applications

Glass is not a new material for Wafer-Level Packaging (WLP) applications and technologies, however, its use is still very limited. Despite its low material cost and incredibly interesting properties , traditional glass microprocessing technologies inevitably increase its cost while negatively affecting the characteristics of glass that made it initially interesting. Laser Induced Deep Etching (LIDE
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) is a glass processing technology, developed by LPKF Laser & Electronics [1], that enables highly precise and reliable micro featuring of glass. After processing, the glass is completely defect-free (no cracks, induced thermal stress, etc.) and retains all of its properties. LIDE consists of a two-step process: i) a maskless, direct-writing laser process that only requires a single pulse to modify the whole glass thickness, and ii) a wet etching process done in batch. In summary, this is an incredibly economical technology capable of bringing new life to glass for microelectronics and enabling its full potential for WLP applications. In this work, we will show how LIDE unlocks the use of glass for RF applications by taking full advantage of fused silica's low transmission loss and by enabling the creation of metallized paths in glass connected to through glass vias (TGV). We will also present high aspect-ratio glass interposers for more affordable 2.5D architectures. The formation of spacer wafers with high-accuracy openings of any shape, the production of capping wafers with anisotropically-etched straight sidewalls that significantly increase their die density, the use of glass springs for high precision passive die alignment features, and high throughput and quality dicing/singulation of glass wafers will also be introduced