A new test structure to measure metal linewidths using minimum real estate

Abstract

Electrical measurement of metal linewidths is generally more demanding than other layers produced in IC processing because of the low resistivity of the material. To enable accurate measurements to be made, an appreciable voltage must be generated. The trade off that arises is in size of test structure against the accuracy of the voltmeter. Presented here is a new structure and method of reconciling this tradeoff, allowing a level of process control without the overhead of a high resolution voltmeter or an unacceptable use of silicon real estate.