This paper presents a case study on reliability reject on a Freescale mixed-mode IC. It focuses on a novel use of one of most frequently used failure localization techniques: static emission microscopy (EMMI) to localize a failure due to an electrical transient behavior. This work helped Freescale to identify a wafer fab process limitation and contributed to test improvement.

This paper presents a case study on scan test reject in a mixed mode IC. It focuses on the smart use of combined mature FA techniques, such as Soft Defect Localization (SDL) and emission microscopy (EMMI), to localize a random scan test anomaly at the silicon bulk level.

The failure localization on analog & mixed mode ICs in functional mode (AC signals) has become more and more challenging in the last few years. Due to an increasing integration and complexity of these devices, the number of defects, especially those named “soft”, raised considerably. The classical Dynamic Laser Stimulation (DLS) techniques showed some limitations when applied to analog & mixedmode ICs. The SDL (Soft Defect Localization) technique [1] based on binary output signal allows us to localize only the most sensitive areas. The defect in this type of circuits, which are very sensitive to the laser beam [2], is often characterized by a weaker sensitivity than that of “healthy” regions. Hence, xVM (Variation Mapping) techniques were introduced to map some parameters in an analog way (the different sensitivity levels are visualized). To date, the T-LSIM technique [3], the Delay and the Phase Variation Mapping techniques were published [4, 5]. We have already had some interesting results by using these techniques [6] but not every “soft” defect case study could be resolved in that way. In this paper we propose to look at some different parameters which characterize an analog signal and can be used as an input for laser mapping. By applying a simple setup, without any additional sophisticated tool, we show on a “golden” commercial IC the added value of this analysis. We also deal with amplifying the weak signal variations induced by the laser beam scan which often are hidden by the high signal variations in analog or mixed-mode ICs.

Soft defect localization techniques based on laser stimulation have become key techniques for a wide range of FA/debug issues. In this paper, we demonstrate the ability of these techniques to solve critical design issue in mixed-mode device for automotive application which includes analog, logic, RF and power. Utilizing a wide range of laser stimulation techniques, we have determined the most efficient approach for this device to achieve the shortest cycle time. We have established a clear link between fault isolation by laser stimulation techniques and the abnormal behavior of the device with relevant and complete simulation at transistor level.