- The highly sensitive fault localization technique of current imaging, combined with parametric extraction ability of the AFP, form a powerful analytical tool. Extension of the single probe atomic force microscope (AFM) technique to a multiple-probe AFP allows the user to perform all necessary measurements to characterize either a failure or to evaluate a process at the contact node level. Imaging requires a few minutes and IV curve extraction a few minutes more. The Resolution of this imaging mode is better than 15pA.
- In the AFP image above, PicoCurrent imaging reveals variations in conductivity across an IC polished to the tungsten contact level. Low resistance paths to ground show higher current and hence darker features. Higher resistances are proportionately lighter. Such contrast provides an instant look at the sample layout, allowing process defects like CVD seams and mis-aligned diffusions to be easily and quickly identified. A corresponding diagram shows how the PicoCurrent sensor operates with the AFP to produce such an image.
- The features of PicoCurrent imaging have been detailed in this Application Note.