Method for determining the alignment of two regions formed in an integrated monolithic (semiconductor) circuit

摘要

A method is described with the aid of which it is possible to determine the alignment of regions (10), produced by means of a first mask, of a first type of an integrated circuit formed in a semiconductor wafer with reference to regions (18, 20, 22), produced by means of a second mask, of a second type in the same integrated circuit. One of the two masks is used in the semiconductor wafer to form a test structure having a region (10) of the first type and to form thereover by means of a second mask and with at least a partial overlap at least one region (18, 20, 22) of the second type. The regions have a prescribed shape with prescribed dimensions. A current is sent through the region (10) of the first type. A voltage drop occurring because of the current flowing through the region (10) of the first type is respectively measured between respectively two tap points, located at the same distance from one another, at one of the two regions. The tap points are provided at locations such that given an exact mutual alignment of the regions of the two types the voltage drops measured between them are the same. The deviation of the regions of the two types from exact mutual alignment is calculated with the aid of the measured voltage drops.