We present the fundamental concept and experimental results of a new optical sensor structure based on a 1D photonic crystal consisting of a polymer light waveguide, a cladding layer and a nanostructured gold layer. The polysiloxane layers are deposited by spin-coating and dip-coating, respectively. The gold nanostructure is deposited by DCmagnetron sputtering and structured by UV-laser lithography. The gold nanowires have a period of about 400 nm and cover an area of 5×5 mm2. This thin flexible structure shows high sensitivity to inclination and strain. Our method enables the fabrication of a new sensor for non-conducting measurement of strain, force, torque and angle.
Electromigration in sub-micron conductors of Cu and CuAl was studied by 1/f noise measurements for the first time. 1/f noise can serve as a very sensitive indicator for electromigration damage: The 1/f noise level is increased by up to two orders of magnitude whereas the resistance of the damaged interconnects is enhanced by less than a factor of two only. The most striking advantage of the 1/f noise measurement technique compared to the methods frequently used at present for electromigration studies (e.g., the Median Time of Failure, MTF technique) is that it is possible to determine the distribution of the activation energies of the processes involved from a single sample at progressive electromigration damaging. In Cu interconnects a strong increase in the number of mobile defects is observed during electromigration damaging whereas the shape of the distribution of the activation energies (maximum between 0.8 and 0.95 eV) does not change much, except shortly before the failure of the interconnect lines where a shift to higher activation energies (maximum: 1.05 eV) is measured. Significantly higher activation energies observed in undamaged and electromigration damaged CuAl0.5wt% interconnects indicate an advanced resistance of CuAl alloys to electromigration when compared to pure Cu lines.