Extraction of Sheet Resistance and Line Width From All-Copper ECD Test Structures Fabricated From Silicon Preforms

Test structures have been fabricated to allow electrical critical dimensions (ECD) to be extracted from copper features with dimensions comparable to those replicated in integrated circuit (IC) interconnect systems. The implementation of these structures is such that no conductive barrier metal has been used. The advantage of this approach is that the electrical measurements provide a nondestructive and efficient method for determining critical dimension (CD) values and for enabling fundamental studies of electron transport in narrow copper features unaffected by the complications of barrier metal films. This paper reports on the results of tests which have been conducted to evaluate various extraction methods for sheet resistance and line width values from the current design.