In this work, two analysis methods for word line (WL) defect localization in NAND flash memory array are presented. One is to use the Emission Microscope (EMMI) and Optical Beam Induced Resistance Change (OBIRCH) to analyze the device through backside, which has no risk of damage during sample preparation. Depending on the I-V characteristics of defects, different analysis tools can be applied. The second method is to analyze a device defect location that is hard to detect through backside analysis. The precise defect site can be localized by Electron Beam Induce Resistance Change (EBIRCH) [1,2], and the defect profile can be observed. The large memory array in NAND flash structure leads to the wide sample movement during EBIRCH analysis. The sub-stage movement function used successfully solves this problem.

Redistribution layer (RDL) bonding pad over active circuitry is utilized to re-route the original bond pad to other location for wire bonding using RDL. The damages in the active circuitry beneath the RDL bond pad induced by stress from wire bonding and package must be evaluated for reliability in the product development. The experimental approach and test structures are proposed in this paper. Functional fail was detected in electrical test after reliability tests on packaged IC. The dielectric cracking initiated by wire bonding that corresponds to the functional fail is identified by physical failure analysis and Transmission-Electron-Microscopy (TEM) at a specific location beneath the RDL bond pad. Finite element simulations are used to analyze the wire bonding stress distribution and circuit-under-pad design effect. The predicted maximum stress for the dielectric cracking matches to the location observed in the physical failure analysis. Based on the experiment and the simulation data, design rules for the circuit routing beneath the RDL bond pad have been successfully developed that all product reliability tests pass later with extend bonding power. The results lead to significant improvements in the robustness of circuit routing structure beneath the RDL bond pad for dielectric cracking without modifications of the existing processes for the product.

A recently developed technique known as Electron Beam Induced Resistance Change (EBIRCH) equipped with a scanning electron microscope (SEM) utilizes a constant electron beam (e-beam) voltage across or current through the defect of interest and amplifies its resistance variation. In this study, EBIRCH is applied for a 3D NAND structure device fault isolation but suffered from nearby dielectric film deformation. The characterization of such dielectric deformation and the possible mechanisms of e-beam induced damage are discussed. As well, a threshold condition to avoid from triggering the occurrence of dielectric damage is presented for shallow defect analysis in EBIRCH application.

Gas quenching is drawing increasing attention within the heat treat industry. The heat transfer coefficient (HTC) for gas quenching can reach 2000 when using high pressure and high velocity nitrogen, helium, or mixtures of these gases. The HTC in water quenching is between 3000 and 4000. The lower HTC of gas quenching may result in workpieces with less distortion and residual stress after quenching. Compared to water, polymer, and oil quenching, gas quenching is environmentally friendly, and the surface of the part is clean after quenching.

A finite element (FE) method was used to determine the important heat treating process parameters that impact the residual stress and distortion in steel. The FE model combines a commercially available heat treatment software DANTE to the finite element analysis software ABAQUS. A thermomechanical FE model was developed to model the evolution of microstructure, the volumetric changes associated with the kinetics of martensitic phase transformation and the formation and distribution of residual stress during quenching of steel. Alternative quenching parameters such as different steel grades, quenching orientation, immersion speed, quenching agent, quenching temperature, austenitizing temperature and part geometry were ranked based on their impact. The main purpose of this paper is to provide processing guidelines to control residual stress and distortion.

To experimentally investigate the effect of tempering temperature and time on the structure and composition of martensite, AISI 52100 was austenized at 1000°C for 40 minutes and quenched in agitated water at 21°C. The as-quenched steel contained body-centered tetragonal (BCT) martensite with 22% retained austenite. These samples were tempered at 100°C, 200°C, and 300°C with different holding times and then were characterized by x-ray diffraction (XRD) to determine the effect on the structure of the martensite. It was found that the content of retained austenite did not change after tempering at 100°C. Retained austenite decomposed after tempering for 40 minutes at 300°C. The changes in crystal structures and lattice parameters for tempered martensite with different holding times and temperatures were measured. The effect of sample preparation on retained austenite and the structure of martensite and tempered martensite was evaluated. An effective technique for carbide extraction and collection in steel is introduced.

This paper presents the results of an experimental investigation of the effect of three types of post-heat treatments: 1) solution treatment and aging, 2) stress relieving, and 3) annealing on the corrosion behavior of Ti-6Al-4V fabricated via direct metal laser sintering (DMLS). The microstructure and phase evolution as affected by heat treatment temperature were examined through scanning electron microscopy and via x-ray diffraction. The Vicker’s microhardness, as it was affected by various heat treatments, was compared. The corrosion behavior of the specimens was measured electrochemically in simulated body fluid at 37°C. It was found that the nonequilibrium α’ phase with a small amount of β nuclei was formed in the as-fabricated sample. Heat treatments allow the formation of the β phase and the agglomeration of β precipitates to occur at elevated temperatures. Transformed β phase with various morphologies was observed as a result of the heat treatments. Different degrees of improvement in the corrosion resistance were observed in the solution-treated and aged samples, 650 °C stress relieved, and annealed samples.

Gas quench, with advantages such as reducing distortion and residual stress, is developing rapidly with the intent to replace liquid quench. Medium and high hardenability steels are needed for gas quench, since the quenching power is lower compared to liquid quench 1 . The traditional Jominy end quench test and Grossmann test, designed for liquid quench steel hardenability, didn’t properly determine the hardenability of high alloyed steels. In order to determine gas quench steel hardenability, a new test is required. In this paper, a critical heat transfer coefficient (HTC) test based on the Grossmann test is proposed. Critical HTC, a concept like critical diameter, was successfully proved to describe the gas quench hardenability of steel. The critical HTC of AISI 4140 steel is 430 W/m 2 C and the critical HTC of AISI 52100 steel is 820 W/m 2 C, which reveals that the gas quench hardenability of 4140 is better than 52100. In the paper, the critical HTC test requirements are presented and discussed.

The 2-bit/cell nitride-trapping device (NROM/Nbit) is an important type of NVM (Non-Volatile Memory). The NROM/Nbit is a potential candidate for replacing FG-type NVM devices below the 45nm node. In this study, electrical and physical failure analyses (PFA) were used. The failure mechanisms and root causes of failure for the test vehicle, a 130nm NBit device, were determined. Because cell dimensions and spacing requirements for high-density memory are quite aggressive, these observations help to optimize process and improve yield.

This report summarizes the analysis results of 0.13µm technology 256Mbits NBit HTOL (High Temperature Operational Life) induced standby current failures caused by STI (Shallow Trench Isolation) punch through induced leakage degradation. Electrical analysis, EMMI and stress experiment on test devices are employed to identify the failure mechanisms, root causes, and corrective solutions. From this study, improvements could be achieved by circuit layout modification.