An in situ air gaps fill-in approach was investigated by conducting a convenient way in dual-beam FIB. We employed a well-controlled deposition to precisely fill carbon into air gaps. It greatly reduced formation of the artifacts and avoided the profiles of air gaps by reducing striations and damages during FIB milling. Generally, the effect of air gaps between wordlines or between metal lines, as well as some unexpected defect voids can be eliminated in most cases if this ideal method is applied.

In cold spraying, oxide-free interface is an important factor for fresh metal bonding between particles and substrate, which determines the bonding strength and final coating quality. In this study, a well-designed experiment was performed to examine the deformation behaviour of the oxide film on copper alloy particle surface after deposition. The experiment results show that partial oxide film could be disrupted during the high-speed impact. However, most of the oxide films were found to remain intact after particle deposition, which limited the exposure of oxide free interface. The presence of oxide film at the interfaces between deposited particles and substrate seriously affected the metallurgical bonding. Besides, substrate material is found to have a strong influence on the deformation behaviour and final state of the oxide film. The study also demonstrated that the bonding mode between deposited particle and substrate strongly depends on the type of substrate.

Since cold spray is widely considered as an additive manufacturing and damage repair technology, it is crucial to understand the coating build-up process and the temperature evolution. In this work, a 3D numerical model was developed to simulate the transient coating build-up process as well as the heat transfer in cold spray. By coupling the heat transfer with the ALE (Arbitrary Lagrangian–Eulerian) moving mesh and coating thickness model, this 3D model is able to investigate the temperature evolution of a coating which simultaneously grows according to the nozzle trajectory. The nozzle trajectory that represents the heat source and mass flux of particle impact is generated and simulated in the offline programming software RobotStudio. By assigning the results of coating thickness distribution, the simultaneous build-up of coating computational domain is achieved by ALE moving mesh method. The validation of the FEA (finite element analysis) model was carried out by measuring the coating surface temperature via an infrared imaging camera. With the proposed model, it is able to study the actual coating build-up process as well as the heat transfer phenomena, which may provide more insights for the application in additive manufacturing and damage repair.

In this study, a numerical model is developed to simulate cold-spray coating profiles based on spray angle, nozzle traverse speed, and scan step. An extension of the model was also developed that predicts coating thickness distributions based on kinematics data obtained using robot trajectory monitoring equipment. Experimental studies were also conducted to validate the numerical models and assess the simulated results.

In this work, we present two case studies on the utilization of advanced nanoprobing on 20nm logic devices at contact layer to identify the root cause of scan logic failures. In both cases, conventional failure analysis followed by inspection of passive voltage contrast (PVC) failed to identify any abnormality in the devices. Technology advancement makes identifying failure mechanisms increasingly more challenging using conventional methods of physical failure analysis (PFA). Almost all PFA cases for 20nm technology node devices and beyond require Transmission Electron Microscopy (TEM) analysis. Before TEM analysis can be performed, fault isolation is required to correctly determine the precise failing location. Isolated transistor probing was performed on the suspected logic NMOS and PMOS transistors to identify the failing transistors for TEM analysis. In this paper, nanoprobing was used to isolate the failing transistor of a logic cell. Nanoprobing revealed anomalies between the drain and bulk junction which was found to be due to contact gouging of different severities.

As silicon manufacturing processes move to smaller feature sizes, new silicon fault isolation and debug challenges arise. This paper presents a methodology for silicon fault isolation/debug that allows for simultaneous probing of multiple locations on the die using static infrared emission logic state imaging. Recent tool enhancements leading to more efficient fault isolation and debug are reviewed. Cases are presented from debug of 65nm products showing how this methodology was used to achieve very low throughput times on a variety of complex new failure mechanisms.

The effect of ash chemistries, N2/H2 and H2, on time-dependent dielectric breakdown (TDDB) lifetime has been investigated for Cu damascene structure with a carbon-doped CVD ultra low-k (ULK, k=2.5) intermetal dielectric. Two failure modes, interfacial Cu-ion-migration and Cu diffusion through the bulk intermetal ULK were attributed to the TDDB degradation for the H2 ash.The interfacial Cu-ion-migration was the only dominated failure mode for the N2/H2 ash. The nitrogen species in the N2/H2 plasma proved to be capable of forming a nitrided protection layer on the surface of the ULK. This nitrided layer suppressed further plasma damage during the ash process and thus lessened the TDDB degradation by preventing Cu diffusion through the bulk ULK.