Conductive thin film residues often referred to as puddles could be challenging fails to detect. A large extant film with no distinct boundaries would make the task more challenging for a comparison between good and bad region. Advanced node 20nm and 14nm technologies mandate use of several conductive thin films in the front end of line processes, and hence a potential for high defects during initial product development stage. Use of other electrical characterization techniques in combination with scanning electron microscopy inspection will be a very powerful tool to detect the root cause affirmatively. Cross-sectional images are necessary to understand the root cause of the fails for corrective actions. This work uses three cases of power supply shorts as a platform to demonstrate the idea, demonstrating a few situations where traditional techniques might reach its limits while the authors depend on additional characterization tools to confidently detect and confirm fails.

Infra-red Thermal Laser Stimulation (TLS) signatures obtained on semiconductor materials can be difficult to interpret and to distinguish from signatures from metallic materials. Investigations presented here consist in the study of TLS signals on unsilicided/silicided polycrystalline and diffused silicon resistors of 0.18µm technology. The influence of each process parameter on the TLS signal has been observed and evaluated from the front and back side of the circuit. This allowed us to quantify the effect of the silicon substrate thickness on TLS signal detection and to determine the ideal silicon thickness for sample preparation. This study also completes our methodology based on the TCR parameter which aims at improving defect localization in the depth (Z) of circuitry. As it will be shown through failure analysis case studies, this methodology increases the physical analysis success rate and reduces the turnaround time.

Ultra-short pulse laser ablation is applied to IC backside sample preparation. It is contact-less, non-thermal, precise and can ablate the various types of material present in IC packages. This study concerns the optimization of ultra-short pulse laser ablation for silicon thinning. Uncontrolled silicon roughness and poor uniformity of the laser thinned cavity needed to be tackled. Special care is taken to minimize the silicon RMS roughness to less than 1µm. Application to sample preparation of 256Mbit devices is presented.

We developed a system and a method to characterize the magnetic field induced by circuit board and electronic component, especially integrated inductor, with magnetic sensors. The different magnetic sensors are presented and several applications using this method are discussed. Particularly, in several semiconductor applications (e.g. Mobile phone), active dies are integrated with passive components. To minimize magnetic disturbance, arbitrary margin distances are used. We present a system to characterize precisely the magnetic emission to insure that the margin is sufficient and to reduce the size of the printed circuit board.

Several considerations related to the implementation of the thermal laser stimulation method (OBIRCH, TIVA) in a failure analysis laboratory will be discussed. At the CNES (French Space Agency), we implemented this method on a dual system which includes an emission microscope and a laser-scanning microscope. The amplifier used for amplifying the weak voltage or current variations caused by thermal laser stimulation was shown to be a key factor. The design of such a low noise, high gain and fast voltage amplifier is described. From a 3D finite element ANSYS model of the thermal laser stimulation effect combined with three practical case studies we show that thermal laser stimulation is a rapid and precise method for localizing metallic short type faults in ICs. In order to interpret the thermal laser stimulation signal, a simple CMOS inverter model is also presented.

Emission microscopy and thermal laser stimulation (OBIRCH, TIVA) are two key methods for backside failure analysis. They are both dedicated for localizing current leakage faults in ICs. The complementary relationship of these two techniques is illustrated through six practical case studies. Thermal laser stimulation was able to precisely and directly localize defects such as shorts in the IC’s metallic elements that where not readily detectable by emission microscopy. The case studies also illustrate the ability of thermal laser stimulation to detect and physically localize defects in the IC’s polysilicon layers and silicon substrate.

To deal with failure analysis laboratory tasks, we have developed a modular and smart test system. We demonstrate that Smart Testing Interface can keep a device in the proper electrical state for defect localization. It is a key part of our system and can be easily adapted on a wide range of electrical testers. It offers a unique combination of a slave and a standalone mode. In slave mode, it has a non-disruptive interface between the tester and the component. In stand-alone mode, it is an electrical stimuli generator that can keep the device under test in the correct internal electrical state during IC defect localization. A battery or a power supply powers it up. It can be readily carried in stand-alone mode from one tool to another tool. In stand-alone mode, it has a range of eight hours or more according to the battery capacity and device consumption. We will review a failure analysis laboratory needs and then describe test solutions with our Modular and Smart Test System and a 344 I/O Smart Testing Interface. It is used for EMMI and OBIRCH applications on PHEMOS 1000.

A new ultra-short pulse laser ablation based backside sample preparation method has been developed. This technique is contact-less, non-thermal, precise, repetitive and adapted to each type of material present in IC packages. Backside preparation examples are presented on a conventional DIL plastic package, on a TSOP plastic package with an oversized silicon die, on a DIL ceramic package and on a CCD device. Feasibility of silicon thinning using laser ablation is also discussed.