Carbon Coating for Electron Beam Testing and Focus Ion Beam Reconfiguration

Author(s):  
P. Perdu ◽  
G. Perez ◽  
M. Dupire ◽  
B. Benteo

Abstract To debug ASIC we likely use accurate tools such as an electron beam tester (Ebeam tester) and a Focused Ion Beam (FIB). Interactions between ions or electrons and the target device build charge up on its upper glassivation layer. This charge up could trigger several problems. With Ebeam testing, it sharply decreases voltage contrast during Image Fault Analysis and hide static voltage contrast. During ASIC reconfiguration with FIB, it could induce damages in the glassivation layer. Sample preparation is getting a key issue and we show how we can deal with it by optimizing carbon coating of the devices. Coating is done by an evaporator. For focused ion beam reconfiguration, we need a very thick coating. Otherwise the coating could be sputtered away due to imaging. This coating is use either to avoid charge-up on glassivated devices or as a sacrificial layer to avoid short circuits on unglassivated devices. For electron beam Testing, we need a very thin coating, we are now using an electrical characterization method with an insitu control system to obtain the right thin thickness. Carbon coating is a very cheap and useful method for sample preparation. It needs to be tuned according to the tool used.

Author(s):  
Z. G. Song ◽  
S. K. Loh ◽  
X. H. Zheng ◽  
S.P. Neo ◽  
C. K. Oh

Abstract This article presents two cases to demonstrate the application of focused ion beam (FIB) circuit edit in analysis of memory failure of silicon on insulator (SOI) devices using XTEM and EDX analyses. The first case was a single bit failure of SRAM units manufactured with 90 nm technology in SOI wafer. The second case was the whole column failure with a single bit pass for a SRAM unit. From the results, it was concluded that FIB circuit edit and electrical characterization is a good methodology for further narrowing down the defective location of memory failure, especially for SOI technology, where contact-level passive voltage contrast is not suitable.


Author(s):  
Julien Goxe ◽  
Béatrice Vanhuffel ◽  
Marie Castignolles ◽  
Thomas Zirilli

Abstract Passive Voltage Contrast (PVC) in a Scanning Electron Microscope (SEM) or a Focused Ion Beam (FIB) is a key Failure Analysis (FA) technique to highlight a leaky gate. The introduction of Silicon On Insulator (SOI) substrate in our recent automotive analog mixed-signal technology highlighted a new challenge: the Bottom Oxide (BOX) layer, by isolating the Silicon Active Area from the bulk made PVC technique less effective in finding leaky MOSFET gates. A solution involving sample preparation performed with standard FA toolset is proposed to enhance PVC on SOI substrate.


Author(s):  
H. Lorenz ◽  
C. Engel

Abstract Due to the continuously decreasing cell size of DRAMs and concomitantly diminishing thickness of some insulating layers new failure mechanisms appear which until now had no significance for the cell function. For example high resistance leakage paths between closely spaced conductors can lead to retention problems. These are hard to detect by electrical characterization in a memory tester because the involved currents are in the range of pA. To analyze these failures we exploit the very sensitive passive voltage contrast of the Focused Ion Beam Microscope (FIB). The voltage contrast can further be enhanced by in-situ FIB preparations to obtain detailed information about the failure mechanism. The first part of this paper describes a method to detect a leakage path between a borderless contact on n-diffusion and an adjacent floating gate by passive voltage contrast achieved after FIB circuit modification. In the second part we will demonstrate the localization of a DRAM trench dielectric breakdown. In this case the FIB passive voltage contrast technique is not limited to the localization of the failing trench. We can also obtain the depth of the leakage path by selective insitu etching with XeF2 stopped immediately after a voltage contrast change.


Author(s):  
Carolyn F. H. Gondran ◽  
Emily Morales

Abstract It is shown that a focused ion beam (FIB) grounding technique can be used to alleviate charge buildup on samples that would otherwise charge in the electron beam to the point where analysis by Auger electron spectroscopy (AES) was limited or impossible. FIB grounding alleviates the sample charging and permits AES analysis. The grounding technique is quick, easy and well understood as it has been used extensively for voltage-contrast analysis. The technique is shown to be useful for enabling analysis on electrically isolated conductive features as well as insulating samples.


Author(s):  
P. E. Russell ◽  
Z. J. Radzimski ◽  
D. A. Ricks ◽  
J. P. Vitarelli

Fundamentally, voltage contrast is a well established technique for determination of voltages on metal surface which can be directly probed with an electron beam. However, actual integrated circuits (IC) consist of two or more conducting layers (metal and doped polysilicon) separated by dielectrics and covered by a dielectric passivation layer. Our work has addressed: i) the removal of dielectric layers (depassivation) by reactive ion etching (RIE) or selectively by focused ion beam etching to allow access to exposed metal lines; ii) modelling effort to understand how the materials and geometric parameters of multilevel IC's affect voltage contrast measurements, and iii) improvements in retarding field spectrometer based measurement techniques.


1998 ◽  
Vol 523 ◽  
Author(s):  
Paul D. Brown ◽  
Colin J. Humphreys

AbstractThe characterisation of semiconductor thin films and device structures increasingly requires the use of a variety of complementary electron microscope-based techniques as feature sizes decrease. We illustrate how layer electrical and structural properties can be correlated: firstly averaged over the bulk and then on the individual defect scale, e.g. scanning transmission electron beam induced conductivity can be used to image the recombination activity of orthogonal <110> misfit dislocations within relaxed MBE grown Si/Si1-xGex/Si(001) heterostructures on the sub-micrometre scale. There is also need for improved understanding of sample preparation procedures and imaging conditions such that materials issues relevant to ULSI development can be addressed without hindrance from artefact structures. Hence, we consider how point defects interact under the imaging electron beam and the relative merits of argon ion milling, reactive ion beam etching, focused ion beam milling and plasma cleaning when used for TEM sample preparation. Advances in sample preparation procedures must also respect inherent problems such as thin foil surface relaxation effects, e.g. cleaved wedge geometries are more appropriate than conventional cross-sections for the quantitative characterisation of δ-doped layers. Choice of the right imaging technique for the problem to be addressed is illustrated through consideration of polySi/Si emitter interfaces within bipolar transistor structures. The development of microscopies for the rapid analysis of electronic materials requires wider consideration of non-destructive techniques of assessment, e.g. reflection high energy electron diffraction in a modified TEM is briefly described.


Author(s):  
Corey Senowitz ◽  
Hieu Nguyen ◽  
Ruby Vollrath ◽  
Caiwen Yuan ◽  
Fati Rassolzadeh ◽  
...  

Abstract The modern scanning transmission electron microscope (S/TEM) has become a key technology and is heavily utilized in advanced failure analysis (FA) labs. It is well equipped to analyze semiconductor device failures, even for the latest process technology nodes (20nm or less). However, the typical sample preparation process flow utilizes a dual beam focused ion beam (FIB) microscope for sample preparation, with the final sample end-pointing monitored using the scanning electron microscope (SEM) column. At the latest technology nodes, defect sizes can be on the order of the resolution limit for the SEM column. Passive voltage contrast (PVC) is an established FA technique for integrated circuit (IC) FA which can compensate for this resolution deficiency in some cases. In this paper, PVC is applied to end-pointing cross-sectional S/TEM samples on the structure or defect of interest to address the SEM resolution limitation.


Author(s):  
Hagit Barda ◽  
Irina Geppert ◽  
Avraham Raz ◽  
Rémy Berthier

Abstract An experimental setup is presented, that allows in-situ Transition Electron Microscopy (TEM) investigation of void formation and growth within fully embedded interconnect structure, as a response to an external bias. A special TEM holder is employed to perform in-situ I-V measurements across the Via, simultaneously monitoring the morphological and chemical changes surrounding the void. This work presents in detail a Focused Ion Beam (FIB) based sample preparation method that allows the analysis of a Cu single Via structure found in the advanced microelectronic 14nm FinFET technology, as well as preliminary TEM observations.


2003 ◽  
Vol 11 (2) ◽  
pp. 22-25 ◽  
Author(s):  
H.J. Engelmann ◽  
B. Volkmann ◽  
Y. Ritz ◽  
H. Saage ◽  
H Stegmann ◽  
...  

TEM sample preparation using Focused Ion Beam (FIB) methods becomes more and more interesting for microscopists because the technique allows for reliable and very efficient sample preparation. The first application of TEM sample preparation by FIB-cutting was reported more than 10 years ago. Meanwhile, a lot of experience has been gathered that allows one to discuss the capabilities and limits of the FIB technique in detail.Several TEM sample preparation techniques are known that all include FIB-cutting but differ in sample pre-preparation, sample handling,etc. This paper focuses on the actual FIB process, FIB tools are closely related to Scanning Electron Microscopes, but instead of an electron beam an ion beam (mostly Ga+ions) is used to remove and deposit material.


2002 ◽  
Vol 733 ◽  
Author(s):  
Brock McCabe ◽  
Steven Nutt ◽  
Brent Viers ◽  
Tim Haddad

AbstractPolyhedral Oligomeric Silsequioxane molecules have been incorporated into a commercial polyurethane formulation to produce nanocomposite polyurethane foam. This tiny POSS silica molecule has been used successfully to enhance the performance of polymer systems using co-polymerization and blend strategies. In our investigation, we chose a high-temperature MDI Polyurethane resin foam currently used in military development projects. For the nanofiller, or “blend”, Cp7T7(OH)3 POSS was chosen. Structural characterization was accomplished by TEM and SEM to determine POSS dispersion and cell morphology, respectively. Thermal behavior was investigated by TGA. Two methods of TEM sample preparation were employed, Focused Ion Beam and Ultramicrotomy (room temperature).


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