Mask Aligner Lithography for TSV-Structures using a Double-Sided (structured) Photomask

Through-silicon vias (TSV) are important for wafer level packaging (WLP) as they provide patterning holes through thick silicon dies to integrate and interconnect devices which are stacked in z-direction. For economic processing TSV fabrication primarily needs to be cost-effective including especially a high throughput. Furthermore, a lithography process for TSV has to be stable enough to allow patterning on pre-structured substrates with inhomogeneous topography. This can be addressed by an exposure process which offers a large depth of focus. We have developed a mask-aligner lithography process based on the use of a double-sided photomask to realize aerial images which meet these constraints.