Large-aperture focusing of Al K(α) 1.49 keV x-ray photons using micropore optics made from a dry-etched 4 in. (100 mm) silicon wafer is demonstrated. Sidewalls of the micropores are smoothed with high-temperature annealing to work as x-ray mirrors. The wafer is bent to a spherical shape to collect parallel x rays into a focus. Our result supports that this new type of optics allows for the manufacturing of ultralight-weight and high-performance x-ray imaging optics with large apertures at low cost.

The suppression of oxygen precipitation in Czochralski silicon (Cz-Si) using the ultrahigh-temperature rapid thermal oxidation (ultrahigh-temperature RTO) technique was investigated by infrared (IR) tomography. The oxygen precipitate nuclei generated during crystal growth were completely dissolved, and the formation of new nuclei due to ultrahigh-temperature RTO was also restrained by controlled slowing of the cooling rate. The ultrahigh-temperature RTO technique is demonstrated to effectively control the oxygen precipitate nucleus formation to yield either uniformly distributed precipitates or completely suppressed precipitation. Our results indicate the flexible and precise control of oxygen precipitation nucleus using ultrahigh-temperature RTO technique is beneficial for device fabrication. Oxygen precipitates in Czochralski Silicon (Cz-Si) wafers effectively act as getter sites for heavy metal impurities in semiconductor devices, 1,2 and they also increase the mechanical strength of the wafer by precipitation hardening.3 Both these roles are important for stable device manufacturing, but oxygen precipitates are also responsible for decreasing the mechanical strength of the wafers if their size and density are not appropriately controlled. 4 In addition, when oxygen precipitates remain in the device formation region, they can result in failure due to current leakage. 5 For this reason, oxygen precipitation must sometimes be suppressed depending on the kind, structure, and process conditions of a semiconductor device. In particular, because of current advances in device structures such as scaling and threedimensional chip integration, precise control of oxygen precipitation will become more significant as the stress induced in Si wafers during device fabrication becomes increasingly crucial.6-8 Therefore, an effective method that can be used for either promoting or suppressing oxygen precipitation in Cz-Si crystals is needed.Many studies have been performed on methods for achieving such precise control of oxygen precipitation. However, maintaining the stability of the growing crystal both in the pulling and radial directions still remains difficult. Thus, both local and widespread nonuniformity often exists in the grown crystal. 9,10 To address this very important problem, we have proposed rapid thermal oxidation (RTO) at ultrahigh temperature (ultrahigh-temperature RTO).11 Our results obviously demonstrated that the oxygen precipitates generated during the crystal growth were dissipated entirely, and dense oxygen precipitate nuclei were formed uniformly in the radial direction during RTO at temperatures over 1350• C. We believed that the newly formed oxygen precipitates in the wafers that had been subjected to ultrahigh-temperature RTO were closely related to preserved vacancies. In particular, each oxygen precipitate nucleus is thought to consist of an oxygen-vacancy complex (for example, O 2 V). 12Ultrahigh-temperature annealing using rapid thermal processing (RTP) has great advantages in terms of uniformit...

Coupled theoretical and computational work is presented aimed at understanding and modelling stimulated Raman backscattering (SRBS) relevant to laser-plasma interactions in large-scale, homogeneous plasmas. With the aid of a new code for simulating and studying the nonlinear coupling in space-time of a large number of modes, and an Eulerian Vlasov-Maxwell code for studying the evolution of large amplitude electron plasma waves, we report results and their interpretations to elucidate the following five observed, nonlinear phenomena associated with SRBS: coupling of SRBS to Langmuir decay instabilities (LDIs); effect of ion-acoustic damping on SRBS; cascading of LDI; stimulated Raman scattering cascades; and stimulated electron acoustic wave scattering (SEAS).

Si(110) and Si(100) directly bonded (DSB) substrates are paid attention as candidate materials for the substrate of next-generation complementary metal oxide semiconductors (CMOSs). From a practical viewpoint on DSB substrates, we have investigated the gettering efficiency at the bonded interfaces of DSB substrates. In our experiments, DSB substrates were intentionally contaminated with 3d transition metals (Fe, Cu, and Ni) and then annealed at 1000 °C. The dependence of the concentrations of these metals on the depth of what was evaluated by secondary ionization mass spectrometry (SIMS). It was found that the bonded interface has a good gettering ability for these metals. Results of the preferential etching method support the results of SIMS. Transmission electron microscopy (TEM) showed that (i) the gettered Fe and Ni formed the silicides FeSi2 and Ni2Si3, respectively; however, (ii) no Cu precipitates formed at the bonded interface. Furthermore, we confirmed that the bonded interface can be effective gettering sites for Cr and Ti. This result indicates that the bonded interface can become effective gettering sites for metals with low diffusivities, if they reach the interface just below the device active layer.

An all-electron density functional theory study of the structure and properties of the neutral and singly charged M 12 and M 13 clusters: M = Sc-Zn Influence of 3d transition metals on the stability and electronic structure of MgH2 J. Appl. Phys. 111, 093720 (2012); 10.1063/1.4714549 When does the non-variational nature of second-order Møller-Plesset energies manifest itself? All-electron correlation energies for open-shell atoms from K to Br J. Chem. Phys. 136, 054107 (2012); 10.1063/1.3679969Atomic diffusion bonding of wafers with thin nanocrystalline metal films Direct silicon bonded ͑DSB͒ substrates with ͑110͒/͑100͒ hybrid orientation technology are attracting considerable attention as a promising technology for high performance bulk complementary metal-oxide semiconductor technology. We have investigated the structure and the gettering efficiency of the ͑110͒/͑100͒ interface parallelling each ͗110͘ direction ͑DSB interface͒ by molecular dynamics ͑MD͒ and first-principles calculation. In MD calculations, initial calculation cells of 15 atomic-configurations with coincidence-site lattices were prepared. It was found that ͑i͒ the calculated DSB interface was stable independent of the initial atomic-configurations and ͑ii͒ the interfacial structures were essentially the same among the calculated models. Moreover, the calculated interfacial structure corresponds to the reported TEM observation. The first-principles calculation showed that Si atoms in the DSB interface formed covalent bonding. The dangling bonds in Si ͑110͒ and ͑100͒ surfaces disappeared due to restructuring in the DSB interface. Furthermore, the DSB interface, which exists just below the device active region, was found to be an efficient gettering site for Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, and Hf atoms.