Suspended Greek cross test structures for measuring the sheet resistance of non-standard cleanroom materials

A novel method is reported to measure the sheet resistance of materials that are incompatible with a CMOS process, using suspended polysilicon Greek cross test structures. To demonstrate the technique, gold (Au) was blanket evaporated in various thicknesses onto the test structures and the sheet resistance extracted. Sheet resistances ranging from 0.30Ω/□to 0.10Ω/□were measured for the deposited Au films on Greek cross structures with arm widths ranging between 5 and 20 μm. The extracted resistivity of 4.85×10^-8Ωm agrees with values found in the literature (3.0×10^-8Ωm-5.0×10^-8Ωm) demonstrating that the structures are fully capable of measuring sheet resistance of blanket deposited films.