Development of panel-level organic lithography equipment for advanced packaging

Abstract

Background: Heterogeneous integration has been used to enhance functionality and improve operation performance by integrating separately manufactured components into system in package. To realize this high density and high performance system, continuous miniaturization is required for Cu interconnect wiring on an organic substrate.Aim: The aim is to clarify the lithography issues for 5 μm L/S Cu wiring formation in the next generation. Lithographic performances, such as resolution, depth of focus (DOF), and overlay accuracy, are evaluated on an organic substrate, and the improvement of lithographic process margin is also investigated. Here, the exposure field of stepper is wide, that is, 62500 mm 2 .Approach: The DOF is calculated and evaluated based on the negative dry film resist with thickness of 15 μm. Overlay accuracy was measured, using a multipoint alignment procedure. Result and Conclusion:First result is patterning. For realizing 5 μm L/S Cu wiring in semi-additive process, resist patterning of 3.5/6.5 or 3∕7 μm L/S is required due to seed Cu layer etching. Under two projection optics conditions (lens C: 5 μm L/S resolution and lens D: 3 μm L/S resolution), the process margin values of 3.5/6.5 and 3∕7 μm L/S were evaluated. It was found that the process margin of 3.5∕6.5 μm L/S is AE40 μm (lens C)/ AE30 μm (lens D), and the process margin of 3∕7 μm L/S is AE10 μm (lens C) AE20 μm (lens D). These process margin values are enough for 5 μm L/S Cu wiring formation. And the second result is overlay. The overlay of the lithography equipment is 1.0 μm or less for deformed substrates while maintaining productivity by simultaneous multipoint measurement.