Sample Preparation and Preservation for TEM Analysis of Copper Interconnect Integrated Circuit

Author(s):  
Qiang Gao ◽  
Mark Zhang ◽  
Ming Li ◽  
Chorng Niou ◽  
W.T. Kary Chien

Abstract This paper examines copper-interconnect integrated circuit transmission electron microscope (TEM) sample contamination. It investigates the deterioration of the sample during ion milling and storage and introduces prevention techniques. The paper discusses copper grain agglomeration issues barrier/seed step coverage checking. The high temperature needed for epoxy solidifying was found to be harmful to sidewall coverage checking of seed. Single beam modulation using a glass dummy can efficiently prevent contamination of the area of interest in a TEM sample during ion milling. Adoption of special low-temperature cure epoxy resin can greatly reduce thermal exposure of the sample and prevent severe agglomeration of copper seed on via sidewall. TEM samples containing copper will deteriorate when stored in ordinary driers and sulphur contamination was found at the deteriorated point on the sample. Isolation of the sample from the ambient atmosphere has been verified to be very effective in protecting the TEM sample from deterioration.

1998 ◽  
Vol 4 (S2) ◽  
pp. 862-863 ◽  
Author(s):  
B. Foran ◽  
F. Shaapur ◽  
V. Blaschke

Sample preparation for transmission electron microscopy (TEM) has been a source of speculation with regards to potential for the creation of artifacts which may confound data gleaned from TEM analysis. For semiconductor integrated circuit (IC) materials characterization, the most common sample preparatory methods are based on final thinning by ion beam milling. The latest shift towards Copper / low dielectric constant (k) composite systems in the semiconductor IC industry provides several challenges for TEM sample preparation resulting from differences in milling rates and materials properties for neighboring features.In conjunction with process development for integration of Cu / low-k materials, conducted at SEMATECH, we have systematically studied the effects of TEM sample preparation by ion milling in order to search for artifacts that could result from sample thinning procedures. For this purpose we have studied wafers with patterned copper lines isolated by a low-k polymer. One sample was stressed by thermal and electronic bias, while a second was subjected to only thermal stress.


Author(s):  
F. Shaapur

Non-uniform ion-thinning of heterogenous material structures has constituted a fundamental difficulty in preparation of specimens for transmission electron microscopy (TEM). A variety of corrective procedures have been developed and reported for reducing or eliminating the effect. Some of these techniques are applicable to any non-homogeneous material system and others only to unidirectionalfy heterogeneous samples. Recently, a procedure of the latter type has been developed which is mainly based on a new motion profile for the specimen rotation during ion-milling. This motion profile consists of reversing partial revolutions (RPR) within a fixed sector which is centered around a direction perpendicular to the specimen heterogeneity axis. The ion-milling results obtained through this technique, as studied on a number of thin film cross-sectional TEM (XTEM) specimens, have proved to be superior to those produced via other procedures.XTEM specimens from integrated circuit (IC) devices essentially form a complex unidirectional nonhomogeneous structure. The presence of a variety of mostly lateral features at different levels along the substrate surface (consisting of conductors, semiconductors, and insulators) generally cause non-uniform results if ion-thinned conventionally.


Author(s):  
Stanley J. Klepeis ◽  
J.P. Benedict ◽  
R.M Anderson

The ability to prepare a cross-section of a specific semiconductor structure for both SEM and TEM analysis is vital in characterizing the smaller, more complex devices that are now being designed and manufactured. In the past, a unique sample was prepared for either SEM or TEM analysis of a structure. In choosing to do SEM, valuable and unique information was lost to TEM analysis. An alternative, the SEM examination of thinned TEM samples, was frequently made difficult by topographical artifacts introduced by mechanical polishing and lengthy ion-milling. Thus, the need to produce a TEM sample from a unique,cross-sectioned SEM sample has produced this sample preparation technique.The technique is divided into an SEM and a TEM sample preparation phase. The first four steps in the SEM phase: bulk reduction, cleaning, gluing and trimming produces a reinforced sample with the area of interest in the center of the sample. This sample is then mounted on a special SEM stud. The stud is inserted into an L-shaped holder and this holder is attached to the Klepeis polisher (see figs. 1 and 2). An SEM cross-section of the sample is then prepared by mechanically polishing the sample to the area of interest using the Klepeis polisher. The polished cross-section is cleaned and the SEM stud with the attached sample, is removed from the L-shaped holder. The stud is then inserted into the ion-miller and the sample is briefly milled (less than 2 minutes) on the polished side. The sample on the stud may then be carbon coated and placed in the SEM for analysis.


Author(s):  
Ching Shan Sung ◽  
Hsiu Ting Lee ◽  
Jian Shing Luo

Abstract Transmission electron microscopy (TEM) plays an important role in the structural analysis and characterization of materials for process evaluation and failure analysis in the integrated circuit (IC) industry as device shrinkage continues. It is well known that a high quality TEM sample is one of the keys which enables to facilitate successful TEM analysis. This paper demonstrates a few examples to show the tricks on positioning, protection deposition, sample dicing, and focused ion beam milling of the TEM sample preparation for advanced DRAMs. The micro-structures of the devices and samples architectures were observed by using cross sectional transmission electron microscopy, scanning electron microscopy, and optical microscopy. Following these tricks can help readers to prepare TEM samples with higher quality and efficiency.


Author(s):  
Chin Kai Liu ◽  
Chi Jen. Chen ◽  
Jeh Yan.Chiou ◽  
David Su

Abstract Focused ion beam (FIB) has become a useful tool in the Integrated Circuit (IC) industry, It is playing an important role in Failure Analysis (FA), circuit repair and Transmission Electron Microscopy (TEM) specimen preparation. In particular, preparation of TEM samples using FIB has become popular within the last ten years [1]; the progress in this field is well documented. Given the usefulness of FIB, “Artifact” however is a very sensitive issue in TEM inspections. The ability to identify those artifacts in TEM analysis is an important as to understanding the significance of pictures In this paper, we will describe how to measure the damages introduced by FIB sample preparation and introduce a better way to prevent such kind of artifacts.


1991 ◽  
Vol 254 ◽  
Author(s):  
John Benedict ◽  
Ron Anderson ◽  
Stanley J. Klepeis

AbstractCross sections of material specimens for TEM analysis must be produced in the shortest time possible, contain few, if any, artifacts and have a large area available for analysis. The analyst must also be able to prepare these cross sections from specified areas of complex, heterogeneous structures on a routine, reproducible basis to meet the growing needs of the semiconductor industry for TEM analysis. The specimen preparation spatial resolution required for preparing precision cross sections is substantially less than one micron. Cross sections meeting these requirements can be prepared by mounting a specimen to the Tripod Polisher and mechanically polishing on one side of the specimen, using a sequence of progressively finer grit diamond lapping films, until the area of interest is reached. This polished surface is then very briefly polished on a cloth wheel with colloidal silica to attain the final polish on that side. The specimen is then flipped over on the Tripod Polisher and polished from the other side, using same sequence of diamond lapping films to reach the predefined area of interest. The Tripod Polisher is set at a slight angle, to produce a tapered, wedge-shaped specimen, which has the area of interest at the thinnest edge of the taper. The specimen is polished with the diamond lapping films and the colloidal silica until it is 1000 Angstroms or less in thickness. The specimen is removed from the polisher and mounted on a 2 × 1mm slotted grid with M-Bond 610 epoxy. After the epoxy is cured the specimen can be taken directly to the microscope for analysis. The need for ion milling has been eliminated or reduced to a few minutes in most of our work because of the thinness of the final specimen. The total specimen preparation time is between 2.5 and 4 hours, depending on the specimen and the size of the specified area. The area available for analysis ranges from 0.5mm up to the full size of the mounting grid opening. The wedge shape of the specimen provides the mechanical stability needed for a long thin specimen.


2021 ◽  
Author(s):  
JungSik Park ◽  
Yoon-Jung Kang ◽  
SunEui Choi ◽  
YongNam Jo

Abstract The main purpose in this paper is a sample preparation of transmission electron microscopy (TEM) for the lithium-ion secondary battery in the form of micro-sized powders. To avoid artefacts of the TEM sample preparation, the use of ion slicer milling for thinning and maintaining the intrinsic structure is described. Argon-ion milling techniques have been widely examined to make the optimized specimen, which makes TEM analysis more reliable. In the past few years, the correction of spherical aberration (Cs) in scanning transmission electron microscopy (STEM) has been developing rapidly, that results in the direct observation with the atomic level resolution not only for the high acceleration voltage but also its deaccelerated voltage as well. Especially, low-kV application has been markedly increased that needs the sufficient-transparent specimen without the structural distortion during the process of the sample preparation. In this study, the sample preparation for the high-resolution STEM observation has been greatly accomplished and investigations of its crystal integrity are carried out by Cs-corrected STEM.


2000 ◽  
Vol 6 (S2) ◽  
pp. 528-529
Author(s):  
C. Urbanik Shannon ◽  
L. A. Giannuzzi ◽  
E. M. Raz

Automated specimen preparation for transmission electron microscopy has the obvious advantage of saving personnel time. While some people may perform labor intensive specimen preparation techniques quickly, automated specimen preparation performed in a timely and reproducible fashion can significantly improve the throughput of specimens in an industrial laboratory. The advent of focused ion beam workstations for the preparation of electron transparent membranes has revolutionized TEM specimen preparation. The FIB lift-out technique is a powerful specimen preparation method. However, there are instances where the “traditional” FIB method of specimen preparation may be more suitable. The traditional FIB method requires that specimens must be prepared so that the area of interest is as thin as possible (preferably less than 50 μm) prior to FIB milling. Automating the initial specimen preparation for brittle materials (e.g., Si wafers) may be performed using the combination of cleaving and sawing techniques as described below.


Author(s):  
S. J. Kirch ◽  
Ron Anderson ◽  
Stanley J. Klepeis

The continuing reduction in the sizes of features of interest for integrated circuit failure analysis requires greater precision in transmission electron microscopy (TEM) sample preparation. With minimum feature sizes approaching 0.5 μm, the mere finding of such a feature at a polished edge, let alone preparing a TEM sample containing it becomes a formidable task. The required substantial thinning also increases the risk of loss of what may be a unique sample.We present in this paper a technique that allows localized thinning of cross-sectional TEM samples using a focused ion beam (FIB) machine. Standard preparation techniques are used to make a cross-sectional TEM sample that would otherwise be too thick to be very useful for TEM analysis. This sample is then placed in the FIB machine, which is used as a micromachining tool. No special surface preparation is necessary and the secondary electron signal generated by the ion beam provides an image that can be used to locate the feature of interest.


Author(s):  
C.S. Bonifacio ◽  
P. Nowakowski ◽  
M.J. Campin ◽  
J.T. Harbaugh ◽  
M. Boccabella ◽  
...  

Abstract The sub-nanometer resolution that transmission electron microscopy (TEM) provides is critical to the development and fabrication of advanced integrated circuits. TEM specimens are usually prepared using the focused ion beam, which can cause gallium-induced artifacts and amorphization. This work presents the use of a concentrated argon ion beam for reproducible TEM specimen preparation using automatic milling termination and targeted ion milling of device features; the result is high-quality and electron-transparent specimens of less than 30 nm. Such work is relevant for semiconductor product development and failure analysis.


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