New Photosensitive Dielectric Material for High-Density RDL with Ultra-Small Photo-Vias and High Reliability

Abstract

This paper presents an advanced ultra-thin photosensitive dielectric Film (PDM) newly developed with high resolution, low CTE and low residual stress for next-generation high-density redistribution layer (RDL), 2.5D interposer, and high-density fan-out package applications. For high-density RDL, photosensitive dielectric materials need to have low CTE to achieve high package reliability. The CTE of the material is 30–35ppm/K. While maintaining the low CTE, we successfully demonstrated the minimum micro-via diameter of 3um in the 5um thickness. Curing temperature of the PDM is 180°C × 60 min. which is lower than most of the advanced dielectric materials which currently used in industry. Low-temperature curing process results in low stress. We have calculated residual stress in the cured PDM from a test result of warpage measurement on 4 inch wafer. As another benefit of the PDM material in curing process, the PDM can be cured in air oven. Most of advanced photo dielectric materials need to cure in N2 oven due to prevent an oxidation of the material. We have demonstrated copper traces of 2um lines and spaced on the PDM by using semi-additive process (SAP) with sputtered Ti/Cu seed layer. Thanks to the low CTE and low residual stress due to the low-temperature curing, it passed temperature cycle test (1,000 cycles) with daisy chain structure which has 400 vias in the structure. It can be concluded that the newly developed PDM is a promising dielectric material for highly reliable high-density redistribution layer (RDL) for 2.5D interposers and fan-out wafer level package applications.

High-speed hybrid complementary ring oscillators based on solution-processed organic and amorphous metal oxide semiconductors

“…3, PDM (the top layer) enables the formation of the OSC and S/D patterns while PMMA facilitated the stripping of the resist with acetonitrile, thus causing little damage to the OSC. The PDM was laminated on the substrate and patterned by photolithography 42,43 , while the PMMA layer was deposited via spin coating and etched with O 2 plasma. Furthermore, the PDM contributed to the damage-free fabrication of OSC-based TFTs as the solvent content in the dry film was <2 wt.% and the PDM patterning process is based on the polymerization of double bonds rather than the generation of photoacids.…”

Scalable High-Speed Hybrid Complementary Integrated Circuits based on Solution-Processed Organic and Amorphous Metal Oxide Semiconductors

“…thus causing little damage to the OSC. The PDM was laminated on the substrate and patterned by photolithography 40,41 , while the PMMA layer was deposited via spin coating and etched with O2 plasma. Furthermore, the PDM contributed to the damage-free fabrication of OSC-based TFTs as the solvent content in the dry film was less than 2 wt.% and the PDM patterning process is based on the polymerization of double bonds rather than the generation of photoacids.…”

“…Fine patterns of OSC and Au S/D electrodes were achieved by a two-step patterning process based on a dry film resist with a thickness of 5 µm (PDM, Taiyo Ink Mfg. Co., Ltd.) 40,41 . This process is illustrated schematically in Figure S10.…”

Scalable High-Speed Hybrid Complementary Integrated Circuits based on Solution-Processed Organic and Inorganic Transistors

“…As shown in Figure S4, PDM (the top layer) enables the formation of the OSC and S/D patterns while PMMA facilitated the stripping of the resist with acetonitrile, thus causing little damage to the OSC. The dry-film photoresist PDM was laminated on the substrate and patterned by photolithography 43,44 , while the PMMA layer was deposited via spin coating and etched with O2 plasma. Furthermore, the PDM dry film contributed to the damage-free fabrication of OSC-based TFTs as the solvent content in the PDM dry film was less than 2 wt.% and the PDM patterning process is based on the polymerization of double bonds rather than the generation of photoacids.…”

“…Fine patterns of OSC and Au S/D electrodes were achieved by a two-step patterning process based on a dry film resist with a thickness of 5 µm (PDM, Taiyo Ink Mfg. Co., Ltd.) 43,44 . This process is illustrated schematically in Figure S10.…”