Physical Failure Analysis techniques for Cu/low k technology

Author(s):  
Huixian Wu ◽  
B. Hooghan ◽  
J. Cargo
Author(s):  
Amy Poe ◽  
Steve Brockett ◽  
Tony Rubalcava

Abstract The intent of this work is to demonstrate the importance of charged device model (CDM) ESD testing and characterization by presenting a case study of a situation in which CDM testing proved invaluable in establishing the reliability of a GaAs radio frequency integrated circuit (RFIC). The problem originated when a sample of passing devices was retested to the final production test. Nine of the 200 sampled devices failed the retest, thus placing the reliability of all of the devices in question. The subsequent failure analysis indicated that the devices failed due to a short on one of two capacitors, bringing into question the reliability of the dielectric. Previous ESD characterization of the part had shown that a certain resistor was likely to fail at thresholds well below the level at which any capacitors were damaged. This paper will discuss the failure analysis techniques which were used and the testing performed to verify the failures were actually due to ESD, and not caused by weak capacitors.


Author(s):  
Kuo Hsiung Chen ◽  
Wen Sheng Wu ◽  
Yu Hsiang Shu ◽  
Jian Chan Lin

Abstract IR-OBIRCH (Infrared Ray – Optical Beam Induced Resistance Change) is one of the main failure analysis techniques [1] [2] [3] [4]. It is a useful tool to do fault localization on leakage failure cases such as poor Via or contact connection, FEoL or BEoL pattern bridge, and etc. But the real failure sites associated with the above failure mechanisms are not always found at the OBIRCH spot locations. Sometimes the real failure site is far away from the OBIRCH spot and it will result in inconclusive PFA Analysis. Finding the real failure site is what matters the most for fault localization detection. In this paper, we will introduce one case using deep sub-micron process generation which suffers serious high Isb current at wafer donut region. In this case study a BEoL Via poor connection is found far away from the OBIRCH spots. This implies that layout tracing skill and relation investigation among OBIRCH spots are needed for successful failure analysis.


Author(s):  
I. Österreicher ◽  
S. Eckl ◽  
B. Tippelt ◽  
S. Döring ◽  
R. Prang ◽  
...  

Abstract Depending on the field of application the ICs have to meet requirements that differ strongly from product to product, although they may be manufactured with similar technologies. In this paper a study of a failure mode is presented that occurs on chips which have passed all functional tests. Small differences in current consumption depending on the state of an applied pattern (delta Iddq measurement) are analyzed, although these differences are clearly within the usual specs. The challenge to apply the existing failure analysis techniques to these new fail modes is explained. The complete analysis flow from electrical test and Global Failure Localization to visualization is shown. The failure is localized by means of photon emission microscopy, further analyzed by Atomic Force Probing, and then visualized by SEM and TEM imaging.


Author(s):  
D. Zudhistira ◽  
V. Viswanathan ◽  
V. Narang ◽  
J.M. Chin ◽  
S. Sharang ◽  
...  

Abstract Deprocessing is an essential step in the physical failure analysis of ICs. Typically, this is accomplished by techniques such as wet chemical methods, RIE, and mechanical manual polishing. Manual polishing suffers from highly non-uniform delayering particularly for sub 20nm technologies due to aggressive back-end-of-line scaling and porous ultra low-k dielectric films. Recently gas assisted Xe plasma FIB has demonstrated uniform delayering of the metal and dielectric layers, achieving a planar surface of heterogeneous materials. In this paper, the successful application of this technique to delayer sub-20 nm microprocessor chips with real defects to root cause the failure is presented.


Author(s):  
C. Ramachandra ◽  
B.M. Sweety ◽  
U.G. Chandan ◽  
D. Jaypal ◽  
Sarat Kumar Dash ◽  
...  

Abstract Removal of polyimide layer after decapsulation of IC package is essential for many of the failure analysis techniques. An alternative method for polyimide removal is described in this paper. The method suggests appropriate modification of dual acid decapsulation system for this purpose. Device integrity is verified after removal of polyimide layer. This method becomes promising for devices which are sensitive / vulnerable for exposure to plasma.


Author(s):  
Robert Chivas ◽  
Scott Silverman ◽  
Michael DiBattista ◽  
Ulrike Kindereit

Abstract Anticipating the end of life for IR-based failure analysis techniques, a method of global backside preparation to ultra-thin remaining silicon thickness (RST) has been developed. When the remaining silicon is reduced, some redistribution of stress is expected, possibly altering the performance (timing) of integrated circuits in addition to electron-hole pair generation. In this work, a study of the electrical invasiveness due to grinding and polishing silicon integrated circuits to ultra-thin (< 5 um global, ~ 1 um local) remaining thickness is presented.


Author(s):  
Huixian Wu ◽  
James Cargo ◽  
Huixian Wu ◽  
Marvin White

Abstract The integration of copper interconnects and low-K dielectrics will present novel failure modes and reliability issues to failure analysts. This paper discusses failure modes related to Cu/low-K technology. Here, physical failure analysis (FA) techniques including deprocessing and cross-section analysis have been developed. The deprocessing techniques include wet chemical etching, reactive ion etching, chemical mechanical polishing and a combination of these techniques. Case studies on different failure modes related to Cu/low k technology are discussed: copper voiding, copper extrusion; electromigration stress failure; dielectric cracks; delamination-interface adhesion; and FA on circuit-under-pad. For the cross-section analysis of copper/low-K samples, focused ion beam techniques have been developed. Scanning electron microscopy, EDX, and TEM analytical analysis have been used for failure analysis for Cu/low-K technology. Various failure modes and reliability issues have also been addressed.


Author(s):  
Charles Zhang ◽  
Matt Thayer ◽  
Lowell Herlinger ◽  
Greg Dabney ◽  
Manuel Gonzalez

Abstract A number of backside analysis techniques rely on the successful use of optical beams in performing backside fault isolation. In this paper, the authors have investigated the influence of the 1340 nm and 1064 nm laser wavelength on advanced CMOS transistor performance.


Author(s):  
Dima A. Smolyansky

Abstract The visual nature of Time Domain Reflectometry (TDR) makes it a very natural technology that can assist with fault location in BGA packages, which typically have complex interweaving layouts that make standard failure analysis techniques, such as acoustic imaging and X-ray, less effective and more difficult to utilize. This article discusses the use of TDR for package failure analysis work. It analyzes in detail the TDR impedance deconvolution algorithm as applicable to electronic packaging fault location work, focusing on the opportunities that impedance deconvolution and the resulting true impedance profile opens up for such work. The article examines the TDR measurement accuracy and the comparative package failure analysis, and presents three main considerations for package failure analysis. It also touches upon the goal and the task of the failure analysts and TDR's specific signatures for the open and short connections.


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