Figure 1. Application space for i-line, DUV and e-beam lithography platforms is plotted as a function of feature size (primary / assist) and CD uniformity. The poly-gate line is based on gate level specifications for 180nm, 130nm and 90nm technology nodes.
ABSTRACTIn the recent past significant work has been done to isolate and characterize suitable single layer Chemically Amplified Resist (CAR) systems for DUV printing applicable to photomask fabrication. This work is complicated by the inherent instability of most DUV CAR systems, particularly in air, showing unacceptable CD degradation over the normal photomask write time in today's DUV mask pattern generators. The high reflectivity of most photomask substrates at DUV wavelengths, creating unacceptable standing waves in the photo resist profile, further compounds this problem.A single layer CAR system suitable for 90nm technology node mask fabrication with DUV printing has been characterized and optimized. Results of this optimization in terms of relevant mask making parameters will be detailed. Furthermore, comparison of the properties of this resist system to other commercially available systems, including FEP-171, will be shown.The pattern fidelity of DUV laser generated masks has been studied in considerable detail. A demonstration of the capabilities of the Etec Systems ALTA™ 4300 will be shown.The pattern fidelity achieved will be compared/contrasted to that achieved with today's leading edge 50KeV vector scan e-beam systems. Advanced methods for modulating the DUV printed patterns' fidelity will be detailed.Finally, the cost and cycle time implications of inserting the DUV laser pattern generator into the mask manufacturing flow will be discussed.