A detailed instruction on cross-sectioning of VLSI thin films and device structures for TEM analysis.

The use of XTEM (cross-sectional TEM) as a diagnostic tool for quality control of device processing has experienced a surge of popularity recently due to the need for better feature resolution and the improvement in equipment and techniques for preparing such samples. As device features shrink below one micrometer, interface morphology and the detection of microstructural defects make TEM a most effective imaging tool. However, the demand for XTEM is tempered by problems in sample preparation, which impose restraints on turnaround time and image quality, especially for devices utilizing multilevel metallizations. A reliable technique for preparing these devices for XTEM observations, along with helpful hints that others may be able to integrate into their routine, will be presented. It reduces turnaround time to about a day and a half per group of samples, its rate of successes is high as long as care is exercised, and all parts of the sample, metallized or not, are electron transparent to produce a clear image with minimized brightness contrast between layers. Finally, micrographs will be presented to illustrate what can be achieved with this technique and what features of interest can be observed for failure analysis determination.