Annual Survey of Virginia Law: Employment Law

This survey covers legislative and judicial developments in Virginia employment law between June 1986 and June 1987. It does not address the workers\u27 compensation and unemployment compensation statutes but focuses on state labor and fair employment laws and the employment-at-will doctrine

Zinc Downregulates HIF-1α and Inhibits Its Activity in Tumor Cells In Vitro and In Vivo

Hypoxia inducible factor-1α (HIF-1α) is responsible for the majority of HIF-1-induced gene expression changes under hypoxia and for the "angiogenic switch" during tumor progression. HIF-1α is often upregulated in tumors leading to more aggressive tumor growth and chemoresistance, therefore representing an important target for antitumor intervention. We previously reported that zinc downregulated HIF-1α levels. Here, we evaluated the molecular mechanisms of zinc-induced HIF-1α downregulation and whether zinc affected HIF-1α also in vivo.Here we report that zinc downregulated HIF-1α protein levels in human prostate cancer and glioblastoma cells under hypoxia, whether induced or constitutive. Investigations into the molecular mechanisms showed that zinc induced HIF-1α proteasomal degradation that was prevented by treatment with proteasomal inhibitor MG132. HIF-1α downregulation induced by zinc was ineffective in human RCC4 VHL-null renal carcinoma cell line; likewise, the HIF-1αP402/P564A mutant was resistant to zinc treatment. Similarly to HIF-1α, zinc downregulated also hypoxia-induced HIF-2α whereas the HIF-1β subunit remained unchanged. Zinc inhibited HIF-1α recruitment onto VEGF promoter and the zinc-induced suppression of HIF-1-dependent activation of VEGF correlated with reduction of glioblastoma and prostate cancer cell invasiveness in vitro. Finally, zinc administration downregulated HIF-1α levels in vivo, by bioluminescence imaging, and suppressed intratumoral VEGF expression.These findings, by demonstrating that zinc induces HIF-1α proteasomal degradation, indicate that zinc could be useful as an inhibitor of HIF-1α in human tumors to repress important pathways involved in tumor progression, such as those induced by VEGF, MDR1, and Bcl2 target genes, and hopefully potentiate the anticancer therapies

Depassivation of Latent Plasma Damage in n-MOSFETs

Indispensable in CMOS manufacturing, plasma treatments may result in a latent damage in gate oxides. We propose a method to detect this latent damage as a function of the area of the multifingered metal pad connected to the gate, by using an experimental method based on constant current stress and oxide trapped charge measurements. We measured a power law behavior describing the dependence of the trapped charge on the injected charge

Radiation induced depassivation of latent plasma damage

The radiation impact on antenna devices can give new insights on basic mechanisms underlying the latent plasma damage nature and radiation hardness of commercial CMOS technologies for space applications. When MOS structures are exposed to ionizing radiation, electron-hole (e/sup -/-h/sup +/) pairs are created along the track of the incident particle. Some fraction of these e/sup -/-h/sup +/ pairs will recombine, and that fraction is a function of the oxide material, the kind of radiation, and the applied oxide electric field. In general, thinner oxides are less prone to radiation effects than thicker ones; applied bias permits to investigate (modulate) the trap creation in the bulk oxide and at the interface. In this study X-rays and e-beam sources have been considered. Although an e-beam LINAC with 8 MeV electrons is a standard source for radiation hardness characterization, its use is difficult for irradiating wafer with a large diameter. On the other side, fully automated protestations with X-ray tubes are commercially available. As a fair comparison, for a given dose and SiO/sub 2/ oxide technology, X-rays usually have a larger detrimental impact on MOSFET I-V characteristics with respect to the e-beam. Electrical stresses reactivate the latent plasma damage as well as ionizing radiation, but fewer studies have addressed the latter aspect and most of them date back to the older MOS technologies of the 70's and 80's. More recently, plasma damage reactivation in a 17.5- nm oxide due to ionizing, radiation has been addressed. The rapid evolution of plasma equipments and MOS technologies, such as the reduction of the gate oxide thickness well below 10 nm and the increase of the metal levels, suggests extending this investigation to more recent CMOS generations. This has been the purpose of this work, which is concentrated on the latent damage reactivation induced by ionizing radiation on a commercial 0.35 /spl mu/m (t/sub ox/=7 nm) CMOS technology

Impact of band structure on charge trapping in thin SiO2/Al2O3/Poly-Si gate stacks

Electron and hole trapping were studied in sub-2-nm SiO2 Al2O3 poly-Si gate stacks. It was found that during substrate injection, electron trapping is the dominant mechanism. Conversely, during gate injection both hole and electron trapping can be observed, depending on the applied bias. These hot carrier effects are closely linked to the band structure of SiO2 Al2O3 poly-Si system

Low field latent plasma damage depassivation in thin oxide MOS

A novel plasma-process induced damage depassivation method is proposed. Using a staircase-like stress voltage and varying the stress time, we were able to depassivate the latent damage at very low-field on both nMOS and pMOS devices. The dynamic of the interface traps generation is studied; pMOS devices show a peculiar behavior, which can be explained understanding the mechanisms involved in damage depassivation. The energy of carriers is identified as the damaging factor

A new experimental technique to evaluate the plasma induced damage at wafer level testing

Plasma processing has become an integral part of the IC fabrication, since it offers advantages in terms of directionality, low temperature and process convenience. However plasma processing induces an oxide charging damage, which is function of process conditions and gate interconnect layout. At the end of the process the plasma damage is "hidden" by hydrogen passivation and becomes latent. At a first electrical inspection all the devices on wafer present nearly the same electrical parameters, whereas a small stress is enough to reveal the plasma damage, producing again a drift of all transistor parameters. In fact the applied stress both depassivate the latent plasma damage and introduce newly defects, which are electrically undistinguishable from plasma damage and depend on applied stress conditions. In our contribution we propose an experimental stress methodology to investigate both the latent damage depassivation effect and the net contribution of plasma damage

Depassivation of latent plasma damage in pMOS devices

While plasma-induced charging damage has been widely studied in recent years, much of the work has concentrated upon the impact on n-channel MOSFET reliability [1-6]. This work focuses the impact of plasma damage on pMOS devices from the viewpoint of oxide trapped charge and interface states with the experimental featuring two parameters Q(P) and Delta N-P, linked respectively to the oxide charge and the interface state density. This experimental method is valid for pMOS devices in two different technologies and permits to fully compare devices with different oxide thickness. Furthermore, we demonstrate that, for a given antenna, the plasma damage roughly has the same net impact on transistor characteristics, regardless of oxide thickness