The split-cross-bridge resistor for measuring the sheet resistance, linewidth, and line spacing of conducting layers

A new test structure was developed for evaluating the line spacing between conductors on the same layer by using an electrical measurement technique. This compact structure can also be used to measure the sheet resistance, linewidth, and line pitch of the conducting layer. Using an integrated-circuit fabrication process, this structure was fabricated in diffused polycrystalline silicon and metal layers. These structures were measured optically and electrically, and these measured value were compared. For the techniques used, the optical measurements were typically one-quarter micrometer greater than the electrical measurements for the polysilicon and metal layers. Most electrically measured line pitch values were within 2 percent of the designed value. A small difference between the measured and designed line pitch is used to validate sheet resistance, linewidth, and line spacing values. Test results confirm the structure's self-checking feature based on the line pitch. That is, a small difference between the measured and designed line pitch is used to validate sheet resistance, linewidth, and line spacing values. Rules for designing the test structure are presented in detail.