Interconnect characterization of X architecture diagonal lines for VLSI design

This paper addresses the manufacturability, yield, and reliability aspects of X Architecture interconnects (diagonal lines) in a very large scale integrated (VLSI) design that enables integrated circuit (IC) chips to become faster and smaller (area) compared to the same design in Manhattan routing. Test chips that consist of comb/serpentine, maze, via chain, as well as resistance and capacitance structures are designed and fabricated using both 130- and 90-nm copper processes. A new technique to characterize interconnect physical parameters (top and bottom line widths, metal line, and dielectric thickness) is developed that requires capacitance measurement on sets of special test structures. An excellent agreement is found between the extracted process parameters, for both diagonal and Manhattan lines, using this technique and those of SEM/FIB data. Measurements of the line resistance, capacitance, and SEM/FIB data on different types of test structures show that 1:1 design rule ratio (Manhattan versus X Architecture) is manufacturable, and the uniformity and fidelity of the diagonal lines are as good as Manhattan lines. The current generation of mask, lithography, wafer processing techniques are applicable to X Architecture designs.

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