Failure Mechanism Studies and Elimination of Galvanic Corrosion (Al-Cu Cell) on Microchip Aluminum Bondpads in Copper Process

2015 ◽  
Author(s):  
Hua Younan ◽  
Chen Yixin ◽  
Fu Chao ◽  
Li Xiaomin
Keyword(s):  
Failure Mechanism ◽  
Galvanic Corrosion ◽  
Metal Layer ◽  
Al Alloy ◽  
Weak Point ◽  
Root Cause ◽  
Weak Points ◽  
Barrier Metal ◽  
Root Cause Identification

Abstract In the authors' previous papers, the failure mechanism and elimination solutions of galvanic corrosion (Al-Cu cell) on microchip Al bondpads in the Al process (0.18un and above) have been studied [1-2]. In this paper, the authors will further study the failure mechanism and root cause of galvanic corrosion (Al-Cu cell) on microchip Al bondpads in the Cu process (0.13um and below) with Ta barrier metal. Based on our results, the root cause of galvanic corrosion (Al-Cu cell) in the Al process is only one way and Al-Cu cell is from Al alloy (Al + 0.5%Cu) on Al bondpads. However, in the Cu process it may be from two ways and Al-Cu cell can be from both Al alloy (Al + 0.5%Cu) on Al bondpads and the Cu metal layer below the barrier metal Ta when Ta has weak points or pinhole. As such, the pinhole defects on Al bondpad caused by galvanic corrosion (Al-Cu cell) in the Cu process might be more serious than that in the Al process. In this paper, TEM is used for root cause identification. Based on the TEM results, galvanic corrosion was due to the weak point/pinhole at the Ta barrier metal layer and Al-Cu diffusion.

Failure Mechanism Studies and Root Cause Identification of Nonstick on Pad on Microchip Al Bondpads

2014 ◽  
Author(s):  
Hua Younan ◽  
Zhou Yongkai ◽  
Chen Yixin ◽  
Fu Chao ◽  
Li Xiaomin
Keyword(s):  
Failure Analysis ◽  
Failure Mechanism ◽  
Wafer Fabrication ◽  
Assembly Process ◽  
Root Cause ◽  
Barrier Metal ◽  
Root Cause Identification ◽  
Induced Defects

Abstract It is well-known that underetch material, contamination, particle, pinholes and corrosion-induced defects on microchip Al bondpads will cause non-stick on pads (NSOP) issues. In this paper, the authors will further study NSOP problem and introduce one more NSOP failure mechanism due to Cu diffusion caused by poor Ta barrier metal. Based on our failure analysis results, the NSOP issue was not due to the assembly process, but due to the wafer fabrication. The failure mechanism might be that the barrier metal Ta was with pinholes, which caused Cu diffused out to the top Al layer, and then formed the “Bump-like” Cu defects and resulted in NSOP on Al bondpads during assembly process.

Case Study—Failure Analysis of a Printed Circuit Board Latent Failure and Resulting Implication of Weaknesses in Panel Coupons and Lot DPA

2017 ◽  
Author(s):  
Tom Tuite
Keyword(s):  
Failure Mechanism ◽  
Printed Circuit Board ◽  
Short Circuit ◽  
Circuit Board ◽  
System Level ◽  
Drilling Process ◽  
Printed Circuit ◽  
Root Cause ◽  
Ionic Contamination ◽  
Root Cause Identification

Abstract Multiple, independent, system level test failures that occurred around the same time were traced back to a short circuit on the same type of printed circuit board (PCB). The PCBs were removed from the application and sent to the authors' lab for analysis. This paper reviews the analysis techniques and results that led to the failure mechanism being identified. The discussion focuses on steps taken to exonerate the authors' lab and processes as possible sources of contamination. Additional investigation that leads to the conclusion that the issue is systemic is also covered. The paper then focuses on the containment effort as well as root cause identification at the manufacturers. It was concluded that the failure mechanism causing the short circuit in the failed PCB is due to ionic contamination trapped inside the PCB. The normal chemistry required to process the plated through holes contaminated the voids/fractures created by drilling process.

Analysis of Leakage Failures in Flash Memory Devices and Root Cause Identification

2000 ◽  
Author(s):  
J. N. C. de Luna ◽  
M. O. del Fierro ◽  
J. L. Muñoz
Keyword(s):  
Flash Memory ◽  
Electromagnetic Interference ◽  
Yield Loss ◽  
High Amplitude ◽  
Physical Analysis ◽  
Input Buffer ◽  
Automated Test Equipment ◽  
Root Cause ◽  
Root Cause Identification ◽  
Test Process

Abstract An advanced flash bootblock device was exceeding current leakage specifications on certain pins. Physical analysis showed pinholes on the gate oxide of the n-channel transistor at the input buffer circuit of the affected pins. The fallout contributed ~1% to factory yield loss and was suspected to be caused by electrostatic discharge or ESD somewhere in the assembly and test process. Root cause investigation narrowed down the source to a charged core picker inside the automated test equipment handlers. By using an electromagnetic interference (EMI) locator, we were able to observe in real-time the high amplitude electromagnetic pulse created by this ESD event. Installing air ionizers inside the testers solved the problem.

Investigation of High Frequency Failures on a 0.35μm CMOS IC

1999 ◽  
Author(s):  
Alan Kennen ◽  
John F. Guravage ◽  
Lauren Foster ◽  
John Kornblum
Keyword(s):  
Failure Analysis ◽  
Failure Mechanism ◽  
Integrated Circuit ◽  
Metal Layer ◽  
Ion Beam ◽  
Stress Test ◽  
Design For Test ◽  
Interface Failure ◽  
Serial Interface ◽  
High Impedance

Abstract Rapidly changing technology highlights the necessity of developing new failure analysis methodologies. This paper will discuss the combination of two techniques, Design for Test (DFT) and Focused Ion Beam (FIB) analysis, as a means for successfully isolating and identifying a series of high impedance failure sites in a 0.35 μm CMOS design. Although DFT was designed for production testing, the failure mechanism discussed in this paper may not have been isolated without this technique. The device of interest is a mixed signal integrated circuit that provides a digital up-convert function and quadrature modulation. The majority of the circuit functions are digital and as such the majority of the die area is digital. For this analysis, Built In Self Test (BIST) circuitry, an evaluation board for bench testing and FIB techniques were used to successfully identify an unusual failure mechanism. Samples were subjected to Highly Accelerated Stress Test (HAST) as part of the device qualification effort. Post-HAST electrical testing at 200MHz indicated that two units were non-functional. Several different functional blocks on the chip failed electrical testing. One part of the circuitry that failed was the serial interface. The failure analysis team decided to look at the serial interface failure mode first because of the simplicity of the test. After thorough analysis the FA team discovered increasing the data setup time at the serial port input allowed the device to work properly. SEM and FIB techniques were performed which identified a high impedance connection between a metal layer and the underlying via layer. The circuit was modified using a FIB edit, after which all vectors were read back correctly, without the additional set-up time.

A New Approach for SRAM Soft Defect Root Cause Identification

2007 ◽  
Author(s):  
Peter Egger ◽  
Stefan Müller ◽  
Martin Stiftinger
Keyword(s):  
Integrated Circuits ◽  
Top Down ◽  
Feature Size ◽  
Design Rules ◽  
New Approach ◽  
Root Cause ◽  
Wafer Fab ◽  
Sram Cell ◽  
Tcad Simulation ◽  
Root Cause Identification

Abstract With shrinking feature size of integrated circuits traditional FA techniques like SEM inspection of top down delayered devices or cross sectioning often cannot determine the physical root cause. Inside SRAM blocks the aggressive design rules of transistor parameters can cause a local mismatch and therefore a soft fail of a single SRAM cell. This paper will present a new approach to identify a physical root cause with the help of nano probing and TCAD simulation to allow the wafer fab to implement countermeasures.

Ethical-cultural Maps of Classical Greek Philosophy: the Contradiction between Nature and Civilization in Ancient Cynicism

Cultura ◽  
2019 ◽  
Vol 16 (1) ◽  
pp. 39-53
Author(s):  
Vytis VALATKA ◽  
Vaida ASAKAVIČIŪTĖ
Keyword(s):  
Swot Analysis ◽  
Greek Philosophy ◽  
Ancient Greek ◽  
Positive Aspect ◽  
Weak Point ◽  
Dio Chrysostom ◽  
Weak Points ◽  
Cultural Maps ◽  
Classical Greek Philosophy ◽  
Ancient Cynicism

This article restores the peculiar ethical-cultural cartography from the philosophical fragments of Ancient Greek Cynicism. Namely, the fragments of Anthistenes, Diogenes of Sinope, Crates, Dio Chrysostom as well as of the ancient historians of philosophy (Diogenes Laertius and Joanes Stobaeus) are mainly analyzed and interpreted. The methods of comparative analysis as well of rational restoration are applied in this article.The authors of the article concentrate on the main characteristics of the above mentioned cartography, that is, the contradiction between maps of nature and civilization. The article comes to the conclusion that the basis of this contradiction is the concept of the main value as well as virtue in the above mentioned cynicism, namely, natural radical temperance. According to ancient cynics, this virtue is absolutely incompatible with pleasure-driven civilization, as the latter annihilates the former. Therefore, cynics interpreted the whole territory of the world known at that time as divided between maps of nature and civilization that never overlap or even intersect. Moreover, according to ancient cynics, the territory covered by maps of civilization is considerably smaller than that enframed by the maps of nature. Moreover, the areas of nature are continuously being diminished, as civilization resolutely goes ahead. In such a situation that threatens survival of human nature the only possible way out is a return to the natural value of radical temperance. After cynics, the only effective strategy of achieving that challenging goal is askesis as excercises of temperance dedicated both to body and spirit.The authors of the article also give a certain SWOT analysis of the above mentioned cartography in the context of contemporary society. According to them, such a cartography possesses both strong and weak points. The main weak point is the contradiction itself between maps of culture and civilization. As a matter of fact, civilization does not annihilate the possibility of natural temperance, whereas a human being, according to his/her nature, is a creator of culture and civilization. On the other hand, the main positive aspect is an emphasis on virtue of temperance, which is actual, significant and relevant in any epoch, culture and civilization, and which is pretty much forgotten nowadays.

scholarly journals Investigation of Zirconium Effect on the Corrosion Resistance of Aluminum Alloy Using Electrochemical Methods and Numerical Simulation in an Acidified Synthetic Sea Salt Solution

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1982 ◽  
Author(s):  
Yong-Sang Kim ◽  
Jong Park ◽  
Byeong-Seon An ◽  
Young Lee ◽  
Cheol-Woong Yang ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Galvanic Corrosion ◽  
Sea Salt ◽  
Al Alloy ◽  
Alloying Element ◽  
Intermetallic Particles ◽  
Transmission Electron ◽  
Corrosion Simulation

Corrosion resistance of Zr that has been added to an Al alloy (U1070) is higher than that of a commercial Al alloy (A1070). A decreasing number and size of Al3Fe intermetallic particles (IMPs) were observed by electron microprobe analysis and transmission electron microscopy. Based on the numerical corrosion simulation, it was confirmed that decreasing the number and size of IMPs was favorable for improving the corrosion resistance of the Al alloy due to the reduction of the galvanic effect. In addition, Al3Zr was found to be insignificant in promoting galvanic corrosion within the Al matrix. Thus, Zr is an advantageous alloying element for improving the corrosion resistance of the Al alloy.

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