High density through glass vias for advanced chip packaging

Glass is a promising material from which advanced interposers for high density electrical interconnects for 2.5D chip packaging can be produced. The supply of ultra-thin glass wafers with thicknesses of 100 µm and below is cost-comparable relative to polished thin wafers made of silicon. As thin glass is extremely brittle, micromachining to create through glass vias is particularly challenging and laser processing using deep UV excimer lasers at a wavelength of 193 nm and ultra-short pulse laser provide a viable solution.In this work, the through glass via drilling capabilities using high energy excimer lasers are shown. Smallest through glass via diameters down to 10 µm with smallest pitch size can be realized using an ultrashort excimer laser wavelength of 193 nm at high laser fluence of several Joules per square centimeter.In favour of volume processing economics, large field size mask illumination supports parallel drilling of up over 1,000 through vias in 30 to 100 µm thin glass sheets. Recent laser ...