This paper explains how to localize metal-to-metal short failures in DRAM using mechanical grinding, plasma FIB delayering, and electron beam induced resistance change (EBIRCH) analysis. Experiments show that the slope created during grinding is compensated by PFIB delayering, producing a high-quality planar surface in the target layer and site. Target layers can thus be prepared at any location (site-free), likewise, defective areas can be delayered to any depth without damage (layer-free). After delayering, exposed surfaces are generally flat enough to allow an electron beam to evenly penetrate the device for precise EBIRCH analysis. With the use of more advanced device preparation methods, EBIRCH analysis has a higher chance of successfully localizing metal line/via shorts even in large regions that include the aluminum layer.

In this paper, we describe the difference between oscilloscope pulsing tests and waveform generator fast measurement unit (WGFMU) tests in analyzing high-resistance defects in DRAM main cells. Nanoprobe systems have various constraints in terms of pulsing whether it involves an oscilloscope or pulse generator. There are certain types of devices, such as DRAM cells, for which these systems are ineffective because saturation currents are too small. In this paper, we address this constraint and propose a new way to conduct pulsing tests using the WGFMU's arbitrary linear waveform generator in combination with an electro-optical nanoprobe.