Accurate low voltage measurements are essential to many semiconductor tests. Often, test structures such as contact chains, vias, and metal structures have resistances on the order of tens to hundreds of milliohms. Measuring such small resistances accurately usually requires forcing current and measuring voltage because most source-measurement instruments have limited low-voltage source accuracy. However, even when current is forced through these structures, the resulting voltages are small, necessitating the use of an accurate voltage measuring instrument, such as a digital multimeter (DMM) with at least 6½ digits of resolution.