Dopant influence on polysilicon capacitor oxide failure
In this work, we investigate polysilicon capacitor oxide defectivity as a function of dopant contamination in a 0.5 /spl mu/m mixed signal process. Experiments show that shallow n and p type dopant implants, used to mimic a cross contamination problem discovered in a PECVD cluster tool, can significantly degrade oxide integrity. Various possible mechanisms of the increased defectivity are discussed.
The effect of gate doping on the electrical conduction and reliability of thick gate oxides
Previous investigations have shown that excessive gate oxide leakage currents at negative gate potentials observed in MOS power products are due to the presence of phosphorus in the gate oxide. During polysilicon gate doping some phosphorus atoms may pile up at the PSi/SiO2 interface and also may diffuse into the gate oxide due to high diffusion temperatures and longer soaking times. Subsequent high temperatures and plasma processing steps result in the ionization of these atoms. The neutralization of these ions during negative gate voltage testing gives rise to abnormal gate oxide leakage currents. It is shown that the presence of any Column V element in the gate oxide, if ionized, will result in excessive gate oxide leakage currents at negative potentials. The level of excessive leakage will depend on the amount of pile up of the impurity at the polysilicon gate/SiO2 interface. Data show that abnormally high gate oxide leakages due to the presence of these impurities in the gate oxide of MOS, IGBT and MCT devices may adversely affect the yield and the long term reliability.
0.6 mu m EPROM cell design based on a new scaling scenario
A novel scaling guideline is proposed for further scaling of EPROM (electrically programmable ROM) cells. Lateral and vertical scaling factors are independently introduced to clarify the scaling effects on cell reliabilities and performances. Based on the proposed scaling scenario, device dimensions and operation voltage designs for 16-Mb EPROM cells are given. 0.6- mu m EPROM cells have been fabricated and the validity of the guideline has been experimentally confirmed.<<ETX>>