Design and characterization of a high-precision resistor ladder test structure

A new subsite stepped multiresistor test structure is introduced. This test structure is used for studying and improving small resistance mismatch patterns in resistor ladders for high-resolution analog-to-digital converter applications. By utilizing wafer prober subsite movements and contact pad cross connections in the test structures, in combination with a Kelvin measurement method and dedicated statistical data evaluation technique, this approach enables identification of very small (<0.05%) systematic resistance mismatch patterns in realistic high- precision resistor ladder implementation. The most disturbing mismatch pattern was found to be caused by mechanical stress from the resistor ladder head layout, while others are attributed to decananometer scale reticle writing artefacts.