Dual channel d.c. low noise measurement system and test methodology

Abstract

A test system having an improved physical layout and electrical design allows the 1/f noise of metal interconnects to be measured at levels close to that of Johnson or thermal noise. A detailed description of examples of operation of the test system provides evidence of the effectiveness of the test system in minimizing system noise to a level significantly lower than Johnson noise. This permits quantitative measurment of the noise contribution attributable to variations in cross-sectional area of connections for various applications and for qualitative prediction of electromigration lifetimes of metal films, particularly aluminum, having different microstructures. The test system includes an enclosure which includes several nested groups of housings including a sample oven within a device under test box which is, in turn, contained within the system enclosure. Wire wound resistors powered by a DC power supply are used to provide heating without interfering with measurement of 1/f noise of a device under test (D.U.T.). A biasing circuit and a bank of batteries are also provided with separate enclosures within the system enclosure.