A Study of Pad Contamination Defect and Removal

2008 ◽  
Author(s):  
K.A. Mohammad ◽  
L.J. Liu ◽  
S.F. Liew ◽  
S.F. Chong ◽  
D.G. Lee ◽  
...  
Keyword(s):  
Failure Analysis ◽  
Gate Oxide ◽  
Action Plans ◽  
Preventive Action ◽  
Oxide Breakdown ◽  
Reliability Level ◽  
The Future ◽  
Dry Etch ◽  
Removal Technique

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.

Failure Analysis for Gate Oxide Breakdown

2008 ◽  
Author(s):  
Xianfeng Chen ◽  
Ming Li ◽  
Qiang Guo ◽  
Kary Chien ◽  
YanBo Gao
Keyword(s):  
Failure Analysis ◽  
Substrate Surface ◽  
Gate Oxide ◽  
Surface Damage ◽  
Process Window ◽  
Mos Capacitors ◽  
Mos Capacitor ◽  
Oxide Breakdown ◽  
Oxide Deposition ◽  
Process Issue

Abstract Damage-free gate oxide is one of the important factors to ensure device performance and reliability. Special wafer accepts test structures such as a large size MOS capacitor must be laid on test line to monitor the oxide process issue and process window. However, it brings about many challenges to failure analysis engineer. To overcome the EFA and PFA limitations, fresh samples were taken from the passed wafer and the failed ones to identify the root cause of VBD failure. A novel lapping down method was used to access the capacitor structure. Two VBD failure cases were studied. In this study, poor wet clean process was defined as the cause of the silicon substrate surface damage and crystalline defect. It induced poor oxide deposition, which reduced breakdown voltage. Additionally, 12hrs BOE dip was shown to be an effective method for removing poly and oxide layers from large MOS capacitors.

ESD Failure Analysis and Robustness Design in Vertical-Diffused MOS Transistors

2014 ◽  
Vol 926-930 ◽  
pp. 456-461
Author(s):  
Shen Li Chen ◽  
Wen Ming Lee ◽  
Chi Ling Chu
Keyword(s):  
Failure Analysis ◽  
Oxide Layer ◽  
Failure Mode ◽  
Epitaxial Layer ◽  
Gate Oxide ◽  
The Other ◽  
Mos Transistors ◽  
Oxide Breakdown ◽  
Analysis Techniques ◽  
Silicon Epitaxial Layer

This paper deals with a detailed study of ESD failure mode and how to strengthen of the VDMOS used for power applications. The ESD post-zapped failure of power VDMOS transistors due to HBM, MM, and CDM stresses are examined in this work. Through standard failure analysis techniques by using EMMI and SEM were applied to identify the failure locations. The MM failure mode in this power MOSFET was caused by the gate oxide breakdown near n+ region in the source end as an ESD zapping. And, the ESD failure damage under HBM and CDM stresses were caused by the gate material molten near the gate pad and tunneled through the oxide layer into silicon epitaxial layer. Furthermore, the ESD robustness designs of power VDMOS transistors are also addressed in this work. The first ESD incorporated design is Zener diodes back-to-back clamping the gate-to-source pad, and on the other hand, another one excellent design contains two Zener diodes clamping the gate-to-source and gate-to-drain terminals of a VDMOS, respectively.

Failure Analysis Methodology on Systematic Defect in N+ poly/NWELL Varactor in RF Analog_PLL due to Implanter Charging Issue

2012 ◽  
Author(s):  
Ang Ghim Boon ◽  
Chen Changqing ◽  
Ng Hui Peng ◽  
Neo Soh Ping ◽  
Magdeliza G ◽  
...  
Keyword(s):  
Problem Solving ◽  
Failure Analysis ◽  
Gate Oxide ◽  
Oxide Breakdown ◽  
Root Cause ◽  
Path Tracing ◽  
Analysis Methodology ◽  
Problem Solving Process ◽  
Access To Data ◽  
Analog Circuitry

Abstract In this paper, a zero yield case relating to a systematic defect in N+ poly/N-well varactor (voltage controlled capacitor) on the RF analog circuitry will be studied. The systematic problem solving process based on the application of a variety of FA techniques such as TIVA, AFP current Imaging and nano-probing, manual layout path tracing, FIB circuit edit, selective etching together with Fab investigation is used to understand the root cause as well as failure mechanism proposed. This process is particularly critical for a foundry company with restricted access to data on test condition setup to duplicate the exact failure as well as no layout tracing available at time of analysis. The systematic defect was due to gate oxide breakdown as a result of implanter charging. It serves as a good reference to other wafer Fabs encountering such an issue.

A New Failure Analysis Flow of Gate Oxide Integrity Failure in Wafer Fabrication

2009 ◽  
Author(s):  
Hua Younan ◽  
Chu Susan ◽  
Gui Dong ◽  
Mo Zhiqiang ◽  
Xing Zhenxiang ◽  
...  
Keyword(s):  
Failure Analysis ◽  
Gate Dielectric ◽  
Dielectric Breakdown ◽  
Defect Density ◽  
Gate Oxide ◽  
Oxide Thickness ◽  
Fault Isolation ◽  
Wafer Fabrication ◽  
Root Cause ◽  
Gate Oxide Integrity

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.

Analysis Approach on DMOS Transistor Vth Mismatch Due to Trapped Charges

2015 ◽  
Author(s):  
Hashim Ismail ◽  
Ang Chung Keow ◽  
Kenny Gan Chye Siong
Keyword(s):  
Failure Analysis ◽  
Threshold Voltage ◽  
Gate Oxide ◽  
Analysis Approach ◽  
Test Results ◽  
Root Cause ◽  
Switching Event ◽  
Output Transistor ◽  
Event Based ◽  
Trapped Charge

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.

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

2008 ◽  
Author(s):  
Suk Min Kim ◽  
Jung Ho Lee ◽  
Jong Hak Lee ◽  
Hyung Ki Kim ◽  
Myung Sick Chang ◽  
...  
Keyword(s):  
Failure Analysis ◽  
Failure Mechanisms ◽  
Electrical Characteristics ◽  
The Future ◽  
Electrical Analysis

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.

Fundamental Considerations for CDM Failure in 90nm Products

2006 ◽  
Author(s):  
Nobuyuki Wakai ◽  
Yuji Kobira ◽  
Hidemitsu Egawa ◽  
Masayoshi Tsutsumi
Keyword(s):  
Breakdown Voltage ◽  
High Speed ◽  
Gate Oxide ◽  
Critical Parameters ◽  
Protection Device ◽  
Oxide Breakdown ◽  
Technology Products ◽  
Charged Device ◽  
Device Size ◽  
Fundamental Consideration

Abstract Fundamental consideration for CDM (Charged Device Model) breakdown was investigated with 90nm technology products and others. According to the result of failure analysis, it was found that gate oxide breakdown was critical failure mode for CDM test. High speed triggered protection device such as ggNMOS and SCR (Thyristor) is effective method to improve its CDM breakdown voltage and an improvement for evaluated products were confirmed. Technological progress which is consisted of down-scaling of protection device size and huge number of IC pins of high function package makes technology vulnerable and causes significant CDM stress. Therefore, it is expected that CDM protection designing tends to become quite difficult. In order to solve these problems in the product, fundamental evaluations were performed. Those are a measurement of discharge parameter and stress time dependence of CDM breakdown voltage. Peak intensity and rise time of discharge current as critical parameters are well correlated their package capacitance. Increasing stress time causes breakdown voltage decreasing. This mechanism is similar to that of TDDB for gate oxide breakdown. Results from experiences and considerations for future CDM reliable designing are explained in this report.

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