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Three dimensional Not-And (3D NAND) flash memory devices are scaling in the vertical direction to more than 200 oxide/sacrificial wordline nitride layers to further increase storage capacity and enhance energy efficiency. The accurate measurement of the thicknesses of these layers is critical to controlling stress-induced wafer warping and pattern distortion. While traditional optical metrology in the UV-vis-NIR range offers a non-destructive inline solution for high volume manufacturing, we demonstrate in this paper, that mid-IR metrology has advantages in de-correlating oxide and nitride thicknesses owing to their unique absorption signatures. Furthermore, because of the depths sensitivity of oxide and nitride absorptions, the simulated measurement results show the ability to differentiate thickness variations in the vertical zones. Good blind test results were obtained with a machine learning model trained on pseudo-references and pseudo spectra with added skew. [ABSTRACT FROM AUTHOR]

Rigorous coupled wave analysis (RCWA) is conducted on in situ spectroscopic ellipsometry data to understand profile evolution during film deposition inside nanotrenches. Lithographically patterned SiO2 nanotrenches are used as test structures. The nanotrenches are 170 nm wide at the top with a taper angle of 4.5° and are 300 nm in depth. Atomic layer deposition of ZnO is used as a model process where the thickness (cycles) of the film is varied from 0 (0 cycles) to 46 nm (300 cycles). The analysis predicts transient behavior in deposition affecting film conformality and changes to the trench taper angle. In the process, the aspect ratio varies from 2.05 at the start of the process to 6.67 at the end. The model predicts changes in the refractive index of the ZnO film as a function of thickness. The real and imaginary parts of the refractive index at a wavelength of 350 nm change from 1.81 to 2.37 and 0.25 to 0.87, respectively. Scanning electron microscopy cross sections confirm thickness at the top and bottom of the trench to within 13% of those predicted by RCWA. The experimentally measured conformality degrades as film deposition proceeds from 97.3% at 100 cycles to 91.1% at 300 cycles. These results demonstrate the potential of using RCWA for continuous and in situ monitoring of growth inside 3D nanostructures. [ABSTRACT FROM AUTHOR]

Objectives. We examined sexually transmitted infection (STI), HIV, and hepatitis virus prevalence and risk behaviors among truck drivers. Methods. We asked participants about their risk behaviors, and we screened them for STIs, HIV, and hepatitis infections. We used logistic regression to identify factors associated with outcomes. Results. Of the 652 enrolled participants, 21% reported sex with sex workers or casual partners in the prior year. Driving solo (odds ratio [OR]=15.04; 95% confidence interval [CI]=1.92, 117.53; P=.01), history of injection drug use (IDU; OR=2.69; 95% CI=1.19, 6.12; P=.02), and history of an STI (OR=2.47; 95% CI=1.19, 5.09; P=.01) were independently associated with high-risk sexual behaviors. Fourteen percent of participants reported drug use in the previous year, and 11% reported having ever injected drugs. Participants tested positive as follows: 54 for HCV antibodies (8.5%), 66 for hepatitis B anticore (anti-HBc) antibodies (10.4%), 8 for chlamydia (1.3%), 1 for gonorrhea (0.2%), 1 for syphilis (0.2%), and 1 for HIV (0.2%). History of injecting drugs (OR=26.91; 95% CI=11.61, 62.39; P Conclusions. Our results suggest a need for hepatitis C screening and STI risk-reduction interventions in this population. (Am J Public Health. 2009;99: 2063-2068. doi: 10.2105/AJPH.2008.145383)

ABSTRACT: All patients attending a sexually transmitted disease (STD) clinic were offered voluntary, anonymous human immunodeficiency virus (HIV)-antibody testing and counseling as part of routine clinical evaluation. During a three-month evaluation period, 82% of patients accepted HIV testing. Testing was accepted equally by men and women and by heterosexual and homosexual men. Black men were more likely to refuse testing than men from other ethnic groups. Eight (0.7%) of 1146 STD clinic patients tested were infected with HIV. A blinded study of 237 patients who refused testing identified nine (3.8%) additional HIV-infected patients. Men who refused testing were 5.3 times more likely to be infected than men who accepted testing. Male homosexuals and black and Hispanic men who refused testing were 7.3 and 8.8 times, respectively, more likely to be infected with HIV than were their counterparts who accepted testing. Human immunodeficiency virus testing and counseling should be routinely offered to STD clinic patients. Male STD clinic patients, especially homosexual or minority men, who refuse voluntary HIV testing should be counseled regarding reducing their risk for HIV transmission.

Using rigorous coupled wave analysis (RCWA) and finite element method (FEM) simulations together, many interesting ellipsometric measurements can be investigated. This work specifically focuses on simulating copper grating structures that are plasmonically active. Looking at near-field images and Mueller matrix spectra, understanding of physical phenomena is possible. A general strategy for combatting convergence difficulties in RCWA simulations is proposed and applied. The example used is a copper cross-grating structure with known slow convergence. Baseline simulations on simple samples are provided for comparison and determination of FEM accuracy. [ABSTRACT FROM AUTHOR]