As advanced device technologies scale to 5nm with dimensions getting smaller and materials change, it is difficult to control the sample preparation delayering end pointing by polishing. Therefore, it requires an alternative solution such as Xe+ PFIB (Plasma Focused Ion beam) Microscopy for accurate delayering control. PFIB can be used for planar Failure Analysis (FA) delayering but also for nanoprobing sample preparation. This paper introduces the detail of nanoprobing sample preparation by PFIB and discusses nanoprobing results on 5nm FinFET technology.

Convention hand polishing, which is widely used for delayering, is becoming increasingly difficult as metal lines and stacks in semiconductor devices get thinner. For one thing, endpointing at the exact targeted layer and region of interest is a major challenge. The presence of cobalt and its propensity to oxidize, thus complicating electrical measurements, is another challenge. In this study, the authors demonstrate an alternative delayering method based on plasma focused ion beam (PFIB) milling aided by DX gas. The workflow associated with the new method is more efficient than that of conventional hand polishing and can help prevent cobalt oxidation.

This paper describes the development and implementation of a TEM-based measurement procedure and shows how it is used to determine the verticality or etching angle of channel holes in V-NAND flash with more than 200 layers of memory cells. Despite the high aspect ratio of the region of interest, the method can resolve offsets down to a few nm. Such precision is critical, as the paper explains, because the radius and thus electrical characteristics of each memory cell is determined by the etching angle.

This paper discusses the development of an automated cell layer counting process for preparing 3D NAND flash memory samples for TEM analysis. In an initial proof-of-concept, several line markings were inscribed on the test device in evenly spaced intervals in order to evaluate its helpfulness for a human operator. A more automated procedure was then developed in which cell layers were counted to a desired target layer starting from a reference layer set by the operator. At that point, the operator could begin preparing the TEM sample.

Focused ion beam (FIB) microscopy is an essential technique for the site-specific sample preparation of atom probe tomography (APT). The site specific APT and automated APT sample preparation by FIB have allowed increased APT sample volume. In the workflow of APT sampling, it is very critical to control depth of the sample where exact region of interest (ROI) for accurate APT analysis. Very precise depth control is required at low kV cleaning process in order to remove the damaged layer by previous high kV FIB process steps. We found low kV cleaning process with 5 kV and followed by 2kV beam conditions delivers better control to reached exact ROI on Z direction. This understanding is key to make APT sample with fully automated fashion.

Correlation across applications and imaging platforms is essential and brings increased insurance for fault isolation in advance of destructive imaging. This paper demonstrates an approach for a detailed advanced packaging defect isolation and analysis workflow. To determine the effectiveness of the proposed workflow, a 28nm flip-chip was used as a test vehicle. By using this workflow, the yield in determining the fault location has increased from 60% to over 85%. To further improve the result, a surface charging mitigation scheme was used and the resulting measured correlative offset between the two systems was found to be less than 10um. This creates novel opportunities in reducing the size of the cross-section and increasing the overall throughput to find the defect, with high confidence. This workflow creates unique abilities in fault localization and analysis as it can detect both opens and shorts between the different techniques that are employed.

In semiconductor manufacturing technology, copper has been widely used for BEOL process due to better conductivity than aluminum. TEM (Transmission Electron Microscopy) characterization has been played in key role to understand the process of semiconductor manufacturing. Gallium base Focused Ion Beam (FIB) is widely used on TEM sample preparation. The experiment to understand the impact of gallium which is from sample preparation process on Cu layer was performed. In-situ TEM studies have shown real time material characteristic of Cu at various temperature [1]. We observed the gallium aggregation phenomenon on Cu layer at round the temperature of 400°C. This thermal aggregation of gallium on Cu layer has been confirmed by EDS analysis in the study. Detectable amount of gallium was found in whole area in the sample before heating the sample at in-situ TEM work. This paper also introduces alternative solutions to resolve this gallium aggregation in copper layer including the sample preparation technique using Xe Plasma Focused Ion Beam (PFIB) [2]. This Xe PFIB showed the substantial improvement of specimen quality for the in-situ TEM experiment of sample preparation.