The Investigation of Oven Contamination and Corresponding Methodology

Author(s):  
W. F. Hsieh ◽  
Henry Lin ◽  
Vincent Chen ◽  
Jun Liu ◽  
Irene Ou ◽  
...  

Abstract Contamination and particle reduction are critical to semiconductor process control. Lots of failure analysis had been focused on finding the root cause of the particle and contamination. The particle and contamination effect were also easily found in circuit probing (CP) process, and therefore induced yield loss and wafer scrap. In the first part of this paper, an oven contamination case was studied. The second part of this paper focus on oven contamination monitoring. In the beginning, a die flying failure was papered at the stage of blue tape and die sawing. This event clearly indicated bad adhesion between die and plastic tape. This bad adhesion was suspected to be a particle/contamination layer formed on bad die surface. Three failure analysis (FA) approaches were performed to find out the root cause. The SEM/EDS result identified the main elements of big particle, but that is insufficient to identify the root cause. The OM/FTIR, however, showed the contamination may be related to polydimethylsiloxane (PDMS). The last failure analysis was the time of fly Secondary Ion Mass Spectrometer (TOF-SIMS), the result confirmed that there was a thin PDMS layer formed on the contaminated bad die surface. The high temperature CP process induced PDMS is believed to be the contamination root cause. In order to prevent the oven contamination event, a methodology based on contact angle and wettability of Si matrix sample was set up for regular monitor in oven operation. The details of contact angle test (CAT) sample preparation, measurement and analysis results were also discussed in this paper.

2018 ◽  
Author(s):  
Andrew Sabate ◽  
Rommel Estores

Abstract The advent of lock-in thermal imaging application on semiconductor failure analysis added capability to localize failures through thermal activity (emission) of the die. When coupled with creative electrical set-up and material preparations, lock-in thermography (LIT) [1, 2] application gives more possibility in exploring the failure of the device using low power settings. This gives higher probability of preserving the defect which leads to a more conclusive root cause determination.


1988 ◽  
Vol 27 (3) ◽  
pp. 333-335
Author(s):  
Khwaja Sarmad

This book is a comprehensive analysis of farmers' movements in India with a focus on the movements in Tamil Nadu, Maharashtra, Punjab and Karnatka. It examines the economic, social and political aspects of the farmers' struggle for a better deal within regional and national perspectives and evaluates the potential impact of these struggles on economic development in general, and on rural development, in particular. In a most competent way the author has presented the current state of the debate on the subject. He deals exhaustively with the subject of agricultural price policy and argues against the proposition that favourable price-setting for farm products is adequate to alleviate rural poverty. A better way to tackle this problem is to improve the per capita output in the rural sector, since the root cause of the problem is not unfavourable terms of trade but the increasing proportion of land holdings, which are economically not viable. Agricultural price policy is analyzed within the context of class relations, which enables to establish a link between the economic and political demands of the farmers. This analysis leads the author to conclude, that in contrast with the peasants' movements in India, which helped to break up the feudal agrarian set-up, the recent farmers' movements, with a few exceptions, have little revolutionary content. Their leadership has been appropriated by the rich landowners, who have transformed the movements into a lobby for advancing their own interests, within the existing power structure, to the neglect of the poorer peasantry.


Author(s):  
Hua Younan ◽  
Chu Susan ◽  
Gui Dong ◽  
Mo Zhiqiang ◽  
Xing Zhenxiang ◽  
...  

Abstract As device feature size continues to shrink, the reducing gate oxide thickness puts more stringent requirements on gate dielectric quality in terms of defect density and contamination concentration. As a result, analyzing gate oxide integrity and dielectric breakdown failures during wafer fabrication becomes more difficult. Using a traditional FA flow and methods some defects were observed after electrical fault isolation using emission microscopic tools such as EMMI and TIVA. Even with some success with conventional FA the root cause was unclear. In this paper, we will propose an analysis flow for GOI failures to improve FA’s success rate. In this new proposed flow both a chemical method, Wright Etch, and SIMS analysis techniques are employed to identify root cause of the GOI failures after EFA fault isolation. In general, the shape of the defect might provide information as to the root cause of the GOI failure, whether related to PID or contamination. However, Wright Etch results are inadequate to answer the questions of whether the failure is caused by contamination or not. If there is a contaminate another technique is required to determine what the contaminant is and where it comes from. If the failure is confirmed to be due to contamination, SIMS is used to further determine the contamination source at the ppm-ppb level. In this paper, a real case of GOI failure will be discussed and presented. Using the new failure analysis flow, the root cause was identified to be iron contamination introduced from a worn out part made of stainless steel.


1998 ◽  
Author(s):  
Leo G. Henry ◽  
J.H. Mazur

Abstract The task of differentiating precisely between EOS and ESD failures continues to be a challenging one for Failure Analysis Engineers. Electrical OverStress (EOS) failures on the die surface (burnt/fused metallization) of an IC can be characterized mainly by the discoloration at the site of the failures. This is in direct contrast to the lack of discoloration characteristic of ESD failures, which occur almost exclusively below the die surface (oxide and junction failures). To aid in this distinction, this paper attempts to present the underlying physics behind the discoloration produced in the EOS failures. For the EOS failures, the metal fuses due to the longer pulse widths (sec to msec), while for the ESD failures, the silicon melts because of the shorter pulse widths (< < 500 nsec) and higher energy. After EOS, the aluminum surface becomes dark and rough and the oxide in the surrounding area becomes deformed and distorted, resulting in the discoloration observed in the light microscope. This EOS discoloration could be due to one or more of the following: 1) morphological and structural changes at the metal/glass interface and the glass itself; 2) changes in the thickness and scattering behavior of the glass and metal in the failed areas.


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):  
Hashim Ismail ◽  
Ang Chung Keow ◽  
Kenny Gan Chye Siong

Abstract An output switching malfunction was reported on a bridge driver IC. The electrical verification testing revealed evidence of an earlier over current condition resulting from an abnormal voltage sense during a switching event. Based on these test results, we developed the hypothesis that a threshold voltage mismatch existed between the sense transistor and the output transistor. This paper describes the failure analysis approach we used to characterize the threshold voltage mismatch as well as our approach to determine the root cause, which was trapped charge on the gate oxide of the sense transistor.


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):  
Erik Paul ◽  
Holger Herzog ◽  
Sören Jansen ◽  
Christian Hobert ◽  
Eckhard Langer

Abstract This paper presents an effective device-level failure analysis (FA) method which uses a high-resolution low-kV Scanning Electron Microscope (SEM) in combination with an integrated state-of-the-art nanomanipulator to locate and characterize single defects in failing CMOS devices. The presented case studies utilize several FA-techniques in combination with SEM-based nanoprobing for nanometer node technologies and demonstrate how these methods are used to investigate the root cause of IC device failures. The methodology represents a highly-efficient physical failure analysis flow for 28nm and larger technology nodes.


Author(s):  
Keith Harber ◽  
Steve Brockett

Abstract This paper outlines the failure analysis of a Radio Frequency only (RF-only) failure on a complex Multimode Multiband Power Amplifier (MMPA) module, where slightly lower gain was observed in one mode of operation. 2 port S-parameter information was collected and utilized to help localize the circuitry causing the issue. A slight DC electrical difference was observed, and simulation was utilized to confirm that difference was causing the observed S-parameters. Physical analysis uncovered a very visible cause for the RF-only failure.


2018 ◽  
Author(s):  
Ong Pei Hoon ◽  
Ng Kiong Kay ◽  
Gwee Hoon Yen

Abstract Chemical etching is commonly used in exposing the die surface from die front-side and die backside because of its quick etching time, burr-free and stress-free. However, this technique is risky when performing copper lead frame etching during backside preparation on small and non-exposed die paddle package. The drawback of this technique is that the copper leads will be over etched by 65% Acid Nitric Fuming even though the device’s leads are protected by chemical resistance tape. Consequently, the device is not able to proceed to any other further electrical measurements. Therefore, we introduced mechanical preparation as an alternative solution to replace the existing procedure. With the new method, we are able to ensure the copper leads are intact for the electrical measurements to improve the effectiveness and accuracy of physical failure analysis.


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