Conductive-AFM for Inline Voltage Contrast Defect Characterization at Advanced Technology Nodes

Author(s):  
Chuan Zhang ◽  
Jochonia Nxumalo ◽  
Esther P.Y. Chen

Abstract Voltage contrast (VC) mode inline E-beam inspection (EBI) at post contact layer provides electrical readout of critical yield signals at an early stage, which could be months before a wafer reaches functional test. Similar to the passive voltage contrast (PVC) technique that is widely used in failure analysis labs, inline VC scanning is based on scanning electron microscopy, where a low keV electron beam scans across the wafer. Conductive atomic force microscopy (CAFM) was successfully implemented as a characterization method for inline VC defects. In this paper, three challenging VC defect analysis case studies are considered: bright voltage contrast (BVC) gate to active short, BVC Junction leakage, and Dark Voltage Contrast gate contact open. Defects exhibiting a hard electrical short, junctional leakage, and open gate contact are used to illustrate how CAFM provides a powerful and comprehensive solution for in-depth characterization of the inline VC defects.

Author(s):  
Chuan Zhang ◽  
Oh Chong Khiam ◽  
Esther P.Y. Chen

Abstract The increase in complexity of process, structure, and design not only increases the amount of failure analysis (FA) work significantly, but also leads to more complicated failure modes. To meet the need of high success rate and fast throughput FA operation at the leading-edge nodes, novel FA techniques have to be explored and incorporated into the routine FA flow. One of the novel techniques incorporated into the presented scan logic FA flow is the conductive-atomic force microscopy (CAFM) technique. This paper demonstrates CAFM technique as a powerful and efficient solution for scan logic failure analysis at advanced technology nodes. Several failure modes in scan logic FA are used as examples to illustrate how CAFM provides excellent solutions to some of the very challenging FA problems. The gate to active short in nFET devices, resistive contact, and open defect on gate contact are some modes used.


Author(s):  
Lucile C. Teague Sheridan ◽  
Linda Conohan ◽  
Chong Khiam Oh

Abstract Atomic force microscopy (AFM) methods have provided a wealth of knowledge into the topographic, electrical, mechanical, magnetic, and electrochemical properties of surfaces and materials at the micro- and nanoscale over the last several decades. More specifically, the application of conductive AFM (CAFM) techniques for failure analysis can provide a simultaneous view of the conductivity and topographic properties of the patterned features. As CMOS technology progresses to smaller and smaller devices, the benefits of CAFM techniques have become apparent [1-3]. Herein, we review several cases in which CAFM has been utilized as a fault-isolation technique to detect middle of line (MOL) and front end of line (FEOL) buried defects in 20nm technologies and beyond.


Author(s):  
Jon C. Lee ◽  
J. H. Chuang

Abstract As integrated circuits (IC) have become more complicated with device features shrinking into the deep sub-micron range, so the challenge of defect isolation has become more difficult. Many failure analysis (FA) techniques using optical/electron beam and scanning probe microscopy (SPM) have been developed to improve the capability of defect isolation. SPM provides topographic imaging coupled with a variety of material characterization information such as thermal, magnetic, electric, capacitance, resistance and current with nano-meter scale resolution. Conductive atomic force microscopy (C-AFM) has been widely used for electrical characterization of dielectric film and gate oxide integrity (GOI). In this work, C-AFM has been successfully employed to isolate defects in the contact level and to discriminate various contact types. The current mapping of C-AFM has the potential to identify micro-leaky contacts better than voltage contrast (VC) imaging in SEM. It also provides I/V information that is helpful to diagnose the failure mechanism by comparing I/V curves of different contact types. C-AFM is able to localize faulty contacts with pico-amp current range and to characterize failure with nano-meter scale lateral resolution. C-AFM should become an important technique for IC fault localization. FA examples of this technique will be discussed in the article.


2016 ◽  
Vol 56 (2) ◽  
Author(s):  
Pavel Geydt ◽  
Prokhor A. Alekseev ◽  
Mikhail S. Dunaevskiy ◽  
Tuomas Haggrén ◽  
Joona-Pekko Kakko ◽  
...  

Current–voltage (I–V) characteristics of vertical p-GaAs nanowires (NWs) covered by different surface passivation materials were experimentally measured by conductive atomic force microscopy (C-AFM). The obtained I–V curves for individual NWs with a diameter of 100 nm covered with AlGaAs, GaN, GaP or InP shell layers were compared to analyse the influence of surface passivation on the density of surface states and choose the most beneficial passivating material for technological applications. We have found the absence of a Schottky barrier between the golden catalytic cap on the top of a NW and the nanowire situated below and covered with an ultrathin GaP passivating layer. It was suggested that passivating material can arrange the heterostructure configuration with the GaAs NW near the Au cap. The latter mechanism was proposed to explain a strong energy barrier found in nanowires covered with InP passivation. AlGaAs passivation affected the forward threshold voltage of nanowires for NWs, which was measured simultaneously with the resistivity of each individual vertical structure from an array by means of AFM in the regime of measuring the I–V curves and onefold calculations. We made an attempt to develop the methodology of measurement and characterization of electric properties of passivated NWs.


2008 ◽  
Vol 112 (49) ◽  
pp. 19680-19685 ◽  
Author(s):  
Pavels Birjukovs ◽  
Nikolay Petkov ◽  
Ju Xu ◽  
Janis Svirksts ◽  
John J. Boland ◽  
...  

2011 ◽  
Vol 1321 ◽  
Author(s):  
Antonín Fejfar ◽  
Petr Klapetek ◽  
Jakub Zlámal ◽  
Aliaksei Vetushka ◽  
Martin Ledinský ◽  
...  

ABSTRACTMicroscopic characterization of mixed phase silicon thin films by conductive atomic force microscopy (C-AFM) was used to study the structure composed of conical microcrystalline grains dispersed in amorphous matrix. C-AFM experiments were interpreted using simulations of electric field and current distributions. Density of absorbed optical power was calculated by numerically solving the Maxwell equations. The goal of this study is to combine both models in order to simulate local photoconductivity for understanding the charge photogeneration and collection in nanostructured solar cells.


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