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In addition to the well-known positive space charge, electron irradiation of MOS capacitors with 25-keV electrons is shown to introduce additional uncharged electron traps into the oxide layer. These traps persist after most of the positively charged defects have been removed by the usual low-temperature (~ 0c) anneals. Their presence after this anneal is determined by injecting hot electrons into the oxide where they are captured by existing defects. The effective trap densities increase with increasing electron fluence and are reduced by forming-gas anneals at temperatures in excess of 500°C. Observed electron-capture cross sections are between 10-15 and 10-18 cm 2 • The residual radiation damage in oxides exposed to 10-4 Ccm-2 of 25-keV electrons and subsequently annealed at 4OQ°C results in an additional neutral density of 5 X 1011 trapscm-2 with cross sections distributed over the above range. Electron-trapping cross sections and effective trap densities associated with this damage are found to be identical at 77 and 295 K. The traps are possibly associated with dipolar defects formed when valence electrons localize around an ion after the bonds are broken.

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We report the voltage-dependence of voltage acceleration for ultra-thin oxides from 2.2V to 5V over a range of Tox values from 1.7nm to 5.0 nm. This unique behavior manifest itself as a power-law voltage-dependence for time-to-breakdown (TBD) over a variety of experimental observations. Using the concept of energy-to-breakdown, we explore the possible scenarios such as fractional energy or defect generation probability as a function of voltage to account for the increase in voltage acceleration with decreasing voltages.

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The location of positive trapped charge in the dry thermally grown films of SiO2 on Si in MOS structures has been investigated by combining the internal photoemission-voltage dependence from both interfaces with the capacitance-voltage technique. Trapped holes have been produced in the SiO2 by vacuum ultraviolet (vuv) photons, x rays, and high-field stressing. After irradiation under positive gate bias, trapped holes have been found to reside near the Si-SiO2 interface with an upper limit of about 50 Å determined for their centroid from this interface. After irradiation under negative bias, a similar situation was found to occur near the Al-SiO2 interface; and in addition some positive charge was found approximately at the Si-SiO2 interface. After high-field stressing under negative bias, positive charge was found approximately at the Si-SiO2 interface. The charge locating technique is described in detail as well as the implications of the results to radiation damage and insulator breakdown.

With wide application of low-dielectric constant (low-k) dielectric materials in multilevel VLSI circuits, the long-term reliability of such materials is rapidly becoming one of the most critical challenges for technology development. Among all the reliability issues, low4 time dependent dielectric breakdown (TDDB) is commonly considered a crucial problem. In this study, the effect of process variations on chemical-vapor deposited (CVD), carbon doped oxide dielectrics comprised of Si, C, 0, and H (SiCOH) TDDB degradation at the 65nm technology node is investigated. SiCOH TDDB is found to be sensitive to all aspects of integration.Based on extensive experimental data, an electrochemical-reactioninduced, three-step degradation model is proposed to explain the SiCOH dielectric breakdown process. Finally, we demonstrate that with careful process and materials optimization, a superior SiCOH TDDB performance at the 65nm technology node can be achieved for 300" fabrication. The projected lifetime, based on a conservative modeling approach and aggressive test structure is far beyond the most stringent reliability target. [

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