New test structure for evaluating low-k dielectric interconnect layers by using ring-oscillators and metal comb/serpentine patterns

We have developed a new test structure for evaluating low-k materials. New structure is composed of several ring-oscillators with metal comb loads and metal serpentine patterns. Metal serpentine pattern was used for correcting the shape effect. Four kinds of low-k materials were evaluated by using the test structures, and relative dielectric constants for these materials were successfully measured. The advantage of the new structure has been confirmed.