Potential and Limits of Texture Measurement Techniques for Inlaid Copper Process Optimization

For future technology nodes with shrunken interconnect dimensions, a thorough texture analysis of the metal interconnects becomes increasingly important in order to optimize and to control the inlaid-copper process. In comparison to plane metal layers deposited on wafers, the microstructure of the metal is more complicated in copper lines and vias which were produced using an inlaid process. Therefore, advanced texture-measurement techniques like X-ray microdiffraction, electron backscatter diffraction (EBSD), and TEM combined with automated crystallography analysis (ACT) are needed to obtain the required microstructure information. These complementary methods are suitable to pick up local as well as integral information on the crystallographic orientation of the copper interconnects and liner materials. Potential and limits of the available techniques and the respective instrumentation are discussed in this paper. Examples of process-monitoring capabilities and of development support, especially with regard to interconnect reliability, are presented.