& CONCLUSIONSCDM (Charged Device Model) is still concerned reliability topic of ESD (Electrostatic Discharge). ESD breakdown voltage tends to lower with Silicon technology down scaling because of lack of energy change in source of ESD stress. Severity for the recent device and reality for actual situation are the reasons why many engineers are investigating aggressively. Fundamental consideration for CDM (Charged Device Model) in the point of breakdown and reliability designing were investigated with the recent semiconductor technology to achieve good endurant device for CDM.According to the result of failure analysis for CDM failed semiconductor device, it was found that gate oxide breakdown was critical failure mode in CDM. For the parameters investigation, Peak intensity and rise time of discharge current are well correlated their package capacitance. To consider this discharge phenomenon in the points of protection circuit, device and package is effective method to achieve well reliable design for CDM breakdown.Moreover there is further investigation. Increasing zapping time in CDM test causes breakdown voltage lowering, which mechanism is similar to that of TDDB for gate oxide breakdown. There is a tendency that an enlargement of semiconductor product scale which is represented with increasing of IC-pin number raises total zapping times in CDM test. Then, excessive CDM zapping stress accumulates its damage into critical gate oxide film and causes breakdown by lower voltage. This phenomenon might be near future concern.These result and consideration from our experiences are explained in this report.
An effective procedure to determine the Burn-In acceleration factors for latest System LSI (Large Scale Integration) with 90nm and 65nm technology are discussed in this paper. The relationship among yield, defect density, and reliability, is well known and well documented for defect mechanisms. In particular, it is important to determine the suitable acceleration factors for temperature and voltage to estimate the exact Burn-In conditions needed to screen these defects. The approach in this paper is found to be useful for recent Cu-processes which are difficult to control from a defectivity standpoint. Performing an evaluation with test vehicles of from 130nm to 65nm technology, the following acceleration factors were obtained, Ea>0.9ev and γ (Gamma)>-5.85.In addition, it was determined that a lower defect density gave a lower Weibull shape parameter. As a result of failure analysis, it is found that the main failures in these technologies were caused by particles, and their Weibull shape parameter "β" was changed depending of the related defect density. These factors can be applied for an immature time period where the process and products have failure mechanisms dominated by defects. Thus, an effective Burn-In is possible with classification from the standpoint of defect density, even from a period of technology immaturity.
Fundamental consideration for CDM (Charged Device Model) breakdown was investigated with 90nm technology products and others. According to the result of failure analysis, it was found that gate oxide breakdown was critical failure mode for CDM test. High speed triggered protection device such as ggNMOS and SCR (Thyristor) is effective method to improve its CDM breakdown voltage and an improvement for evaluated products were confirmed. Technological progress which is consisted of down-scaling of protection device size and huge number of IC pins of high function package makes technology vulnerable and causes significant CDM stress. Therefore, it is expected that CDM protection designing tends to become quite difficult. In order to solve these problems in the product, fundamental evaluations were performed. Those are a measurement of discharge parameter and stress time dependence of CDM breakdown voltage. Peak intensity and rise time of discharge current as critical parameters are well correlated their package capacitance. Increasing stress time causes breakdown voltage decreasing. This mechanism is similar to that of TDDB for gate oxide breakdown. Results from experiences and considerations for future CDM reliable designing are explained in this report.
An effective procedure to determine the Burn-In acceleration factors for 130nm and 90 nm processes are discussed in this paper. The relationship among yield, defect density, and reliability, is well known and well documented for defect mechanisms. In particular, it is important to determine the suitable acceleration factors for temperature and voltage to estimate the exact Burn- In conditions needed to screen these defects. The approach in this paper is found to be useful for recent Cu-processes which are difficult to control from a defectivity standpoint. Performing an evaluation with test vehicles of 130nm and 90nm technology, the following acceleration factors were obtained, Ea>0.9ev and β (Beta)>-5.85. In addition, it was determined that a lower defect density gave a lower Weibull shape parameter. As a result of failure analysis, it is found that the main failures in these technologies were caused by particles, and their Weibull shape parameter “m” was changed depending of the related defect density. These factors can be applied for an immature time period where the process and products have failure mechanisms dominated by defects. Thus, an effective Burn-In is possible with classification from the standpoint of defect density, even from a period of technology immaturity.
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