Failure Analysis Case Study in 0.18μm Flash Memory Devices and Root Cause Identification

2003 ◽  
Author(s):  
Wen-Rong Chen ◽  
Mao-Sheng Wu ◽  
Chi-Ling Chu
Keyword(s):  
Flash Memory ◽  
Defect Density ◽  
Failure Mechanisms ◽  
Storage Test ◽  
Root Cause ◽  
High Temperature Storage ◽  
Program Function ◽  
Root Cause Identification ◽  
Temperature Storage

Abstract This report summarizes the analysis of 0.18µm Flash ROM technology qualification failure cases at Macronix. The cases include single cell read failures, erase/program function failures, and high temperature storage test failures. Electrical analysis, EMMI and physical check by chemical de-processing, parallel lapping, FIB, SEM, PVC and TEM techniques were employed to identify the failure mechanisms, root causes, and solutions. From this study, improvements were achieved in process defect density, test fault coverage and product reliability of the 0.18µm Flash ROM technology.

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.

Copper Ball Voids: Failure Mechanisms and Methods of Controlling at High Temperature Automotive Application

2019 ◽  
Vol 2019 (DPC) ◽  
pp. 000519-000530
Author(s):  
Chu-Chung Lee ◽  
TuAnh Tran ◽  
Varughese Mathew ◽  
Rusli Ibrahim ◽  
Poh-Leng Eu
Keyword(s):  
High Temperature ◽  
Void Formation ◽  
High Volume ◽  
Automotive Application ◽  
Corrosion Mechanism ◽  
Adhesion Promoter ◽  
Storage Test ◽  
Ball Bond ◽  
High Temperature Storage ◽  
Temperature Storage

Since 2008, fine gauge (≤ 35 μm diameter) copper (Cu) wire has been rapidly replacing fine gauge gold (Au) wire in consumer, commercial, and industrial products [2–4]. The first wave of Cu wire products used bare, uncoated Cu wire which is soon to known having Cu-Al IMC corrosion induced by mobile chlorine ions in the epoxy mold compound system when IC parts are subjected to moisture related package stress tests such as biased HAST (Highly Accelerated Stress Test) [1–7]. Additionally, when comparing to Au wires, the 2nd bond process window of bare Cu wire can be very narrow and becomes a concern of moving into HVM (high volume manufacturing) [8]. Thus, palladium-coated Cu (PdCu) wire was introduced to the semiconductor assembly market aiming to provide more margin of passing biased HAST and enhance 2nd bond process capability [9–13]. However, the use of Pd-Cu wire is not a panacea to all Cu wire bond problems. One unique anomaly for Pd-Cu wire is the Cu ball void [1] which is observed only with Pd-Cu and not bare Cu ball bonds during HTSL (high temperature storage life) tests. The mechanism of forming Cu ball voids was proven to be the galvanized corrosion mechanism with Pd-Cu coupling. Significant factors affecting the formation rate of Cu ball voids are found to be baking temperature, EFO current settings, bonding parameters and mold compound additives (sulfur). Both anodic and cathodic chemical reactions will be proposed for Cu voids in this paper. Even though Cu void can be considered as a cosmetic defect for the majority of application since the peak temperature of device mission profile is always no larger than 175C. The application at extreme high temperature (for example, 190C) can actually cause electrical failure at the ball bon region due to the Cu void formation in terms of size and location at the Cu-Al IMC region. The main effect is due to the selected mold compound having high amount of metallic adhesion promoter which is sulfur-based and extensive high temperature storage test condition (190C). The FIB/SEM picture of failing ball bond due to Cu voids from this particular device will be presented in the paper. Thus, a newly developed doped Cu wire without Pd coating has been proposed by many wire suppliers to overcome Cu ball voids. However, doped Cu wires without Pd coating have suffered the same high volume manufacturing issues observed by bare Cu wires. For example, short tail and mean time between assist (MTBA) for doped Cu wires without Pd coating are both as poor as bare Cu wires. We will present high temperature storage test results obtained by doped PdCu wires in this paper. To balance high volume manufacturing issues and Cu void formation, doped PdCu wires are also proposed recently. Several doped PdCu wires whose extensive high temperature storage results (220C) will be presented in this paper. The worst case mold compound with high amount of sulfur based adhesion promoter has been used to test the effectiveness of these new wire types. At such harsh testing condition, there is one doped PdCu wire in our test can actually survive without electrical failed ball bond due to Cu voids. Factors of effectiveness of doped PdCu wires will be discussed in this paper. Authors have chosen to focus on Cu voids at both 1st bond (ball bond) and 2nd bond (wedge). 20 um wire diameter has been used for all test vehicle in this study. All controlling factors of eliminating Cu voids will surely be included at the end of this paper.

scholarly journals Spatial Qualification Tests for Highly Selective Compact Micromachined Band Pass Planar Filters

2012 ◽  
Vol 2012 ◽  
pp. 1-4
Author(s):  
Raghida Hajj ◽  
Matthieu Chatras ◽  
Pierre Blondy ◽  
Olivier Vendier ◽  
Wolfgang Tschanum ◽  
...  
Keyword(s):  
Center Frequency ◽  
Band Pass Filter ◽  
Storage Test ◽  
Pass Filter ◽  
Small Influence ◽  
High Temperature Storage ◽  
Radiation Test ◽  
Band Pass ◽  
Insertion Losses ◽  
Temperature Storage

A highly selective planar band pass filter is proposed for satellite receivers to suppress intermodulation components. The 4-pole filter has a center frequency of 19.825 GHz with a bandwidth of 240 MHz. The measured quality factor is over 600 and the insertion losses are 4.1 dB. The micromachining technological process is used to fabricate this filter. A BCB (benzocyclobutene) thin layer is used as an electrical and mechanical support for the filter. The compatibility of the BCB with the spatial constraints was tested. Various tests were accomplished for this purpose and the results of all these tests are presented in the paper. The tests showed a very small influence of the temperature variation and high temperature storage test and practically no influence of the radiation test on the circuit.

Stability Investigation of High Heat-Resistant Resin under High Temperature for Ultra-High Blocking Voltage SiC Devices

2013 ◽  
Vol 740-742 ◽  
pp. 669-672 ◽  
Author(s):  
Toru Izumi ◽  
Tetsuro Hemmi ◽  
Toshihiko Hayashi ◽  
Katsunori Asano
Keyword(s):  
High Temperature ◽  
Linear Thermal Expansion ◽  
High Heat ◽  
Storage Test ◽  
Heat Resistant ◽  
Blocking Voltage ◽  
High Temperature Storage ◽  
Higher Temperature ◽  
Insulation Performance ◽  
Temperature Storage

The reliability of three kinds of high heat-resistant resins has been evaluated under high temperatures. These resins were applied to insulation substrates and a high temperature storage test has been carried out. The insulation performance of the resins was evaluated by applying 20 kV between a pair of electrodes on the substrate covered with resin. The insulation performance at 20 kV was maintained in samples with two of the three kinds of resins for 1,000 hours at 225oC. In a higher temperature storage test at 250oC, samples with one of the kinds of resin were not able to maintain insulation of 20 kV for 200 hours, while the two remaining resins were not able to maintain the insulation for 1,000 hours. In most samples that were not able to maintain the insulation, cracks or detachments were seen. Hardening caused by oxidation of the resin and differences in the coefficient of linear thermal expansion (CTE) are considered as causes of the cracks or detachments. It is thought to be necessary to lower the CTE of the resin and inhibit its oxidation in order to use it at more than 250oC for long periods of time.

scholarly journals Root Cause Analysis of a Printed Circuit Board (PCB) Failure in a Public Transport Communication System

2022 ◽  
Vol 12 (2) ◽  
pp. 640
Author(s):  
Cher-Ming Tan ◽  
Hsiao-Hi Chen ◽  
Jing-Ping Wu ◽  
Vivek Sangwan ◽  
Kun-Yen Tsai ◽  
...  
Keyword(s):  
Printed Circuit Board ◽  
Failure Modes ◽  
Essential Element ◽  
Circuit Board ◽  
Cause Analysis ◽  
Printed Circuit ◽  
Root Cause ◽  
Burn Out ◽  
Root Cause Identification

A printed circuit board (PCB) is an essential element for practical circuit applications and its failure can inflict large financial costs and even safety concerns, especially if the PCB failure occurs prematurely and unexpectedly. Understanding the failure modes and even the failure mechanisms of a PCB failure are not sufficient to ensure the same failure will not occur again in subsequent operations with different batches of PCBs. The identification of the root cause is crucial to prevent the reoccurrence of the same failure. In this work, a step-by-step approach from customer returned and inventory reproduced boards to the root cause identification is described for an actual industry case where the failure is a PCB burn-out. The failure mechanism is found to be a conductive anodic filament (CAF) even though the PCB is CAF-resistant. The root cause is due to PCB de-penalization. A reliability verification to assure the effectiveness of the corrective action according to the identified root cause is shown to complete the case study. This work shows that a CAF-resistant PCB does not necessarily guarantee no CAF and PCB processes can render its CAF resistance ineffective.

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