Copper/low-k process characterization for 90nm technology using SEM and TEM imaging
Artificial vertical and lateral shrinkage of different carbon-doped oxide (CDO) low-k materials is observed for electron beam exposure. The effect depends on SEM and TEM imaging conditions and sample preparation procedures. Typical artifacts include layer thinning and delamination of the CDO material from surrounding materials. TEM imaging is less critical compared to SEM. This is partly due to the favorable conditions during TEM sample preparation employing ion milling steps, which avoid the mechanical stress of conventional SEM sample cross-sectioning. Samples also absorb less energy from the electron beam during TEM scanning, which minimizes the impact of CDO shrink. Some artifacts are difficult to distinguish from real process issues, e.g. de-lamination caused by poor layer adhesion. Therefore, careful sample preparation and imaging are necessary to provide meaningful information.
Failures in copper interconnects-localization, analysis and degradation mechanisms
In this paper, we focussed about the failures in copper interconnects and on analytical techniques that are applied for physical failure analysis. Electromigration test structure after partial degradation by voiding was observed using SEM images.
TEM Sample Preparation Using Focused Ion Beam - Capabilities And Limits
TEM sample preparation using Focused Ion Beam (FIB) methods becomes more and more interesting for microscopists because the technique allows for reliable and very efficient sample preparation. The first application of TEM sample preparation by FIB-cutting was reported more than 10 years ago. Meanwhile, a lot of experience has been gathered that allows one to discuss the capabilities and limits of the FIB technique in detail. Several TEM sample preparation techniques are known that all include FIB-cutting but differ in sample pre-preparation, sample handling, etc. This paper focuses on the actual FIB process, FIB tools are closely related to Scanning Electron Microscopes, but instead of an electron beam an ion beam (mostly Ga+ ions) is used to remove and deposit material.