Development of novel fine line 2.1 D package with organic interposer using advanced substrate-based process

Development of 2.1D package with organic interposer in panel size based on the high resolution dry film photo resist and the ultra-thin electro-less copper seed layer will be reported in this paper. The aim of 2.1D technology is to focus on the reducing of production cost and increase I/O counts simultaneously. Compare to the wafer level lithography process, substrate-based process leads to the benefit in cost reduction and risk elusion form chip first process. Dry film photo resist and electro-less copper seed layer processes can significantly save the equipment and material cost compared to the wafer patterning process. High density interconnection routings are integrated on an organic film in 25 μm thickness. Micro-bump is designed as 25 μm size with 40 μm pitch. Embedded trace substrate (ETS) also reported here by using plated nickel seed layer as etching resistance, copper trace with 3 μm width and spacing embedded in the organic film can be achieved. This designed 2.1D organic interposer substrate has passed MSL3 (Moisture Soaking Level 3) standard and TCT (Thermal Cycling Test) reliability test with 1000 cycles. In terms of electrical property study, the electrical measurement including DC resistance and S-parameter is performed to tell apart the different performance of dielectric and photo resist materials, and the result show agreement with the formed appearance of copper traces.