Failure Analysis of Single Shared Column Fail in DRAM Using Nano-Probing Technique

Author(s):  
Suk Min Kim ◽  
Jung Ho Lee ◽  
Jong Hak Lee ◽  
Hyung Ki Kim ◽  
Myung Sick Chang ◽  
...  

Abstract We report an analysis of a single shared column fail on DRAM technology using a nano-probing technique in this work. The electrical characteristics of the failed transistors show that the column fails were caused by two different failure mechanisms: abnormal contact and implant profiles. We believe that electrical analysis using nano-probing will be a powerful tool for non-visible failure analysis in the future because it is impossible to clearly reveal these two different failure mechanisms solely using physical failure methods.

Author(s):  
Randal Mulder ◽  
Sam Subramanian ◽  
Ed Widener ◽  
Tony Chrastecky

Abstract Single bit failures are the dominant failure mode for SRAM 6T bit cell memory devices. The analysis of failing single bits is aided by the fact that the mechanism is localized to the failing 6T bit cell. After electrically analyzing numerous failing bits, it was observed that failing bit cells were consistently producing specific electrical signatures (current-voltage curves). To help identify subtle bit cell failure mechanisms, this paper discusses an MCSpice program which was needed to simulate a 6T SRAM bit cell and the electrical analysis. It presents four case studies that show how MCSpice modeling of defective 6T SRAM bit cells was successfully used to identify subtle defect types (opens or shorts) and locations within the failing cell. The use of an MCSpice simulation and the appropriate physical analysis of defective bit cells resulted in a >90% success rate for finding failure mechanisms on yield and process certification programs.


Author(s):  
Ng Sea Chooi ◽  
Chor Theam Hock ◽  
Ma Choo Thye ◽  
Khoo Poh Tshin ◽  
Dan Bockelman

Abstract Trends in the packaging of semiconductors are towards miniaturization and high functionality. The package-on-package(PoP) with increasing demands is beneficial in cost and space saving. The main failure mechanisms associated with PoP technology, including open joints and warpage, have created a lot of challenges for Assembly and Failure Analysis (FA). This paper outlines the sample preparation process steps to overcome the challenges to enable successful failure analysis and optical probing.


Author(s):  
E. Widener ◽  
S. Tatti ◽  
P. Schani ◽  
S. Crown ◽  
B. Dunnigan ◽  
...  

Abstract A new 0.5 um 1 Megabit SRAM which employed a double metal, triple poly CMOS process with Tungsten plug metal to poly /silicon contacts was introduced. During burn-in of this product, high currents, apparently due to electrical overstress, were experienced. Electrical analysis showed abnormal supply current characteristics at high voltages. Failure analysis identified the sites of the high currents of the bum-in rejects and discovered cracks in the glue layer prior to Tungsten deposition as the root cause of the failure. The glue layer cracks allowed a reaction with the poly/silicon, causing opens at the bottom of contacts. These floating nodes caused high currents and often latch-up during burn-in. Designed experiments in the wafer fab identified an improved glue layer process, which has been implemented. The new process shows improvement in burn in performance as well as outgoing product quality.


Author(s):  
K.A. Mohammad ◽  
L.J. Liu ◽  
S.F. Liew ◽  
S.F. Chong ◽  
D.G. Lee ◽  
...  

Abstract The paper focuses on the pad contamination defect removal technique. The defect is detected at the outgoing inspection step. The failure analysis results showed that the defect is Fluorine type contamination. The failure analysis indicated many source contributors mainly from Fluorine based processes. The focus is in the present work is in the rework method for the removal of this defect. The combination of wet and dry etch processing in the rework routine is utilized for the removal of the defect and preventive action plans for in-line were introduced and implemented to avoid this event in the future. The reliability of the wafer is verified using various tests including full map electrical, electrical sort, gate oxide breakdown (GOI) and wafer reliability level, passivation quick kill to ensure the integrity of the wafer after undergoing the rework routine. The wafer is monitored closely over a period of time to ensure it has no mushroom defect.


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):  
Tomokazu Nakai

Abstract Currently many methods are available to obtain a junction profile of semiconductor devices, but the conventional methods have drawbacks, and they could be obstacles for junction profile analysis. This paper introduces an anodic wet etching-based two-dimensional junction profiling method, which is practical, efficient, and reliable for failure analysis and electrical characteristics evaluation.


Author(s):  
J.G. van Hassel ◽  
Xiao-Mei Zhang

Abstract Failures induced in the silicon substrate by process marginalities or process mistakes need continuous attention in new as well as established technologies. Several case studies showing implant related defects and dislocations in silicon will be discussed. Depending on the electrical characteristics of the failure the localization method has to be chosen. The emphasis of the discussion will be on the importance of the right choice for further physical de-processing to reveal the defect. This paper focuses on the localization method, the de- processing technique and the use of Wright etch for subsequent TEM preparation.


Author(s):  
Cha-Ming Shen ◽  
Yen-Long Chang ◽  
Lian-Fon Wen ◽  
Tan-Chen Chuang ◽  
Shi-Chen Lin ◽  
...  

Abstract Highly-integrated radio frequency and mixed-mode devices that are manufactured in deep-submicron or more advanced CMOS processes are becoming more complex to analyze. The increased complexity presents us with many eccentric failure mechanisms that are uniquely different from traditional failure mechanisms found during failure analysis on digital logic applications. This paper presents a novel methodology to overcome the difficulties and discusses two case studies which demonstrate the application of the methodology. Through the case studies, the methodology was proven to be a successful approach. It is also proved how this methodology would work for such non-recognizable failures.


Author(s):  
Julie Segal ◽  
Arman Sagatelian ◽  
Bob Hodgkins ◽  
Tom Ho ◽  
Ben Chu ◽  
...  

Abstract Physical failure analysis (FA) of integrated circuit devices that fail electrical test is an important part of the yield improvement process. This article describes how the analysis of existing data from arrayed devices can be used to replace physical FA of some electrical test failures, and increase the value of physical FA results. The discussion is limited to pre-repair results. The key is to use classified bitmaps and determine which signature classification correlates to which type of in-line defect. Using this technique, physical failure mechanisms can be determined for large numbers of failures on a scale that would be unfeasible with de-processing and physical FA. If the bitmaps are classified, two-way correlation can be performed: in-line defect to bitmap failure, as well as bitmap signature to in-line defect. Results also demonstrate the value of analyzing memory devices failures, even those that can be repaired, to gain understanding of defect mechanisms.


Author(s):  
Hui Peng Ng ◽  
Ghim Boon Ang ◽  
Chang Qing Chen ◽  
Alfred Quah ◽  
Angela Teo ◽  
...  

Abstract With the evolution of advanced process technology, failure analysis is becoming much more challenging and difficult particularly with an increase in more erratic defect types arising from non-visual failure mechanisms. Conventional FA techniques work well in failure analysis on defectively related issue. However, for soft defect localization such as S/D leakage or short due to design related, it may not be simple to identify it. AFP and its applications have been successfully engaged to overcome such shortcoming, In this paper, two case studies on systematic issues due to soft failures were discussed to illustrate the AFP critical role in current failure analysis field on these areas. In other words, these two case studies will demonstrate how Atomic Force Probing combined with Scanning Capacitance Microscopy were used to characterize failing transistors in non-volatile memory, identify possible failure mechanisms and enable device/ process engineers to make adjustment on process based on the electrical characterization result. [1]


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