The availability of high brilliance 3rd generation synchrotron sources together with progress in achromatic focusing optics allow to add submicron spatial resolution to the conventional century-old X-ray diffraction technique. The new capabilities include the possibility to map in-situ, grain orientations, crystalline phase distribution and full strain/stress tensors at very local level, by combining white and monochromatic X-ray microbeam diffractions. This is particularly relevant for nowadays industry where the understanding of material properties at microstructural level becomes increasingly important. After describing the latest advances in the submicron X-ray diffraction technique at the ALS, we will give some examples of its application in material science for the measurement of strain/stress in metallic thin films and interconnects, MEMS devices and composite materials. Its use in the field of environmental science will also be discussed.

The structural properties of thin film as well as bulk samples are critically determined by their mesoscale structure (i.e. the submicron to micron range structure of grain boundaries, dislocations, inclusions, voids,+). The ability to measure with high accuracy local texture and triaxial stress variations is primary for the understanding of major scientific and technological issues such as failure in integrated circuit interconnects and deformation and grain growth during material synthesis. For this purpose we have developed at the Advanced Light Source, a dedicated X-ray microdiffraction beamline combining white and monochromatic beam capabilities. By bending into plane ellipses a pair of Kirkpatrick-Baez flat mirrors, we were able to achieve a beam size of about 0.8 by 0.9 microns. A 4-crystal Ge or Si monochromator in front of the focussing mirrors can be moved in and out of the beam and allows the ability to be able to switch back and forth between white and monochromatic beam, whilst illuminating the same small spot on the sample. The actual measurement technique consists of illuminating the sample with the submicron broad bandpass (white) beam and collecting the X-ray outgoing reflections using a large area (9 x 9 cm) CCD detector. The orientation and the full deviatoric (distortional) strain/stress tensor of the illuminated area are directly derived from the analysis of the resulting Laue patterns. The dilatational component of the strain is obtained by switching to monochromatic beam and making energy scans on selected reflections. The sample is mounted on a precise positioning stage that allows the sample to be scanned This procedure has been successfully applied to the study of residual strain in passivated Al and Cu interconnect tests structures as well as in Cu blanket films. The evolution of the inter- and intragranular texture and strain has also been studied as a function of temperature. In situ electromigration experiments have been carried out on

The availability of high brilliance synchrotron sources, coupled with recent progress in achromatic focusing optics and large area 2D detector technology, have allowed us to develop an X-ray synchrotron technique capable of mapping orientation and strain/stress in polycrystalline thin films with submicron spatial resolution. To demonstrate the capabilities of this instrument, we have employed it to study the microstructure of aluminum thin film structures at the granular and subgranular level. Owing to the relatively low absorption of X-rays in materials, this technique can be used to study passivated samples, an important advantage over most electron probes given the very different mechanical behavior of buried and unpassivated materials.

When crystalline materials are mechanically deformed in small volumes, higher stresses are needed for plastic flow. This has been called the "smaller is stronger" phenomenon and has been widely observed. Various size-dependent strengthening mechanisms have been proposed to account for such effects, often involving strain gradients. Here we report on a search for strain gradients as a possible source of strength for single-crystal submicron pillars of gold subjected to uniform compression, using a submicron white-beam (Laue) X-ray diffraction technique. We have found, both before and after uniaxial compression, no evidence of either significant lattice curvature or subgrain structure. This is true even after 35percent strain and a high flow stress of 300 MPa were achieved during deformation. These observations suggest that plasticity here is not controlled by strain gradients or substructure hardening, but rather by dislocation source starvation, wherein smaller volumes are stronger because fewer sources of dislocations are available. (31 References).

In the present paper the evolution of the dislocation structure during electromigration in different regions along the Al(Cu) interconnect line is considered. It is shown that plastic deformation increases in the regions close to cathode end of the interconnect line. A coupling between the dissolution, growth and re-precipitation of Al2Cu precipitates and the electromigration-induced plastic deformation of grains in interconnects is observed. Possible mechanism of the Cu doping effect on the improved electromigration resistance of the Al(Cu) interconnects is discussed.

The mass transport of Cu during electromigration (EM) testing is typically dominated by interface diffusion. If a mechanism other than interface diffusion begins to affect the overall transport process, then the effective diffusivity, D, of the EM process would deviate from that of interface diffusion only. This would have fundamental implications. We have preliminary evidence that this might be the case, and we report its implications for EM lifetime assessment in this manuscript. (11 References).