Several potential solutions exist for patterning large area panels with a resolution of 2-micron line and space or better. This resolution is required for flip chip mounting of modern chips having a pad pitch of 40 microns or less.
- Use of flat panel display (FPD) technology. The CANON MPAsp-E903T is a wide-field lithographic system capable of resolving 1.2µm line and space features across Gen6 glass panels that measure 1500 x 1850mm.
- Maskless imaging by EV GROUP achieves 2µm line and space resolution with no substrate size limitation. This equipment may be too slow for volume production but could be used to prototype microelectronic modules.
- Use of SHINKO technology for producing finely patterned redistribution layers on organic substrates, following their i-THOP substrate structure.
However, a fourth possibility could enable the desired result without requiring a huge investment in new equipment. The proposed solution involves stepping-and-repeating of reticle images using available lithographic equipment.
If each tile is associated with a reticle-sized image, a pattern comprising multiple tiles can be step-and-repeated across a large size panel. If each tile implements an independently operable cluster of components, a minimal set of interconnections may be required between neighboring tiles. The interconnections may be created by stitching, wherein overlay errors of the order of 10µm may be acceptable.