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Purpose: Hyperperfusion syndrome (HPS) after carotid artery stenting (CAS) causes serious symptoms; therefore, early evaluation after CAS is considered to be important. Measurement of cerebral blood volume using C‑arm computed tomography (C-arm CBV) has recently become possible. Here, the usefulness of C‑arm CBV for the evaluation of hyperperfusion was investigated.Methods: C-arm CBV was measured before and immediately after CAS in 30 patients. The regions of interest (ROI) were set in the bilateral middle cerebral artery perfused regions, and the affected/healthy side ratio of measured C‑arm CBV (CBV ratios) was determined to evaluate cerebral perfusion. For comparing values before and after CAS, the CBV ratio increase rate (postoperative CBV ratios/preoperative CBV ratios) was also determined.Results: C-arm CBV was successfully measured in 30 patients. Intracerebral hemorrhage (ICH) was detected in 3 patients, and no other patient had hyperperfusion syndrome. In the patients who developed ICH, postoperative C‑arm CBV on the affected side was high, and a marked increase was confirmed in the postoperative CBV ratios. Postoperative CBV ratios were 1.03 ± 0.40 and 1.45 ± 0.68 in the non-ICH and ICH groups, and CBV ratio increase rates were 2.7 ± 24.0% and 28.5 ± 26.7% in the non-ICH and ICH groups, respectively; these differences were statistically significant (P < 0.01).Conclusion: C-arm CT allows CBV measurements immediately after CAS without requiring transport of the patient out of the angiography room, and it may enable the evaluation of hyperperfusion before and after CAS. [ABSTRACT FROM AUTHOR]

Steep channel profiles of scaled transistors are a promising approach for advancing transistor generation in bulk complementary metal–oxide–semiconductor (MOS). In this paper, a carbon-doped Si (Si:C) layer under an undoped Si layer is proposed to form steep p-type channel profiles in n-channel MOS field-effect transistors (nMOSFETs) due to extremely low diffusivity of boron and indium in Si:C layers. This structure with low channel impurity improves mobility and suppresses threshold voltage (VTH) variation. Both items are essential for aggressively scaled MOSFETs with a gate length less than 25 nm. We demonstrated well-controlled, high-performance, and low VTH variability nMOSFETs with a Si:C-Si epitaxial channel structure. [ABSTRACT FROM PUBLISHER]

We have successfully fabricated uniaxially strained SOI (SSOI) FinFETs with high electron mobility and low parasitic resistance. The high electron mobility enhancement on the (110) fin sidewall surfaces was obtained by utilizing effective subband engineering through uniaxial tensile strain along (110), while the substantial reduction of the parasitic resistance was achieved by selective Si epitaxy on the source and drain regions. It was experimentally found that the electron mobility on the (110) sidewall surfaces was significantly enhanced (2.6 x ) and even surpassed the (100) universal mobility (1.2 x). This high mobility enhancement is mainly attributed to the electron repopulation from fourfold valleys having a heavier mass along (110) to twofold valleys having a lighter one. In addition, the effective mass reduction of the twofold valleys due to conduction band warping and/or the suppressed surface roughness scattering can also be responsible for the mobility enhancement. Thanks to these high electron mobility enhancement and low parasitic resistance large performance enhancement of 35% was realized in uniaxially SSOI FinFETs with a gate length of 50 nm. This enhancement was evaluated to be as high as ~80% (= 35%/45%) of the intrinsic strain-induced enhancement of the short-channel device performance (45%) at the same strain level (0.8%, ~1.5 GPa) and gate length. [ABSTRACT FROM AUTHOR]

Meningioma usually grows and expands into the brain, but invasion into the brain parenchyma is relatively rare. Meningioma arises from arachnoid cap cells, and infiltration into dura mater is the main growth pattern of meningiomas. However, little is known about the mechanism of meningioma invasion into the dura mater. In this study, seven specimens, including dural attachments, from seven cases of meningioma were used for immunohistochemical analysis. Matrix metalloproteinase (MMP)-1, -2, -9, urokinase-type plasminogen activator (uPA), vascular endothelial growth factors (VEGF), flt-1, E-cadherin, estrogen receptor (EgR), progesterone receptor (PgR), and aquaporin (AQP)-1, -4 were used as primary antibodies. There were several patterns of meningioma invasion into the dura mater: papillary-shaped invasion with destruction of dural structure, infiltration along the fibers of the dura mater, and invasion of several tumor cell units with fibroblast infiltration. Strong immunostaining was obtained with MMP-1, followed by AQP-1 and uPA, within the invading tumor cells. Neovasculature and extravasated erythrocytes, which stained with AQP-1, were also occasionally observed around the invading tumor cells. Simpson grade II removal of meningiomas results in high recurrence rates, and the inhibition of meningioma growth via dural invasion will facilitate improved remission in many cases with meningioma. In this study, MMP-1, AQP-1, and uPA are considered to have some role in the dural infiltration of meningioma cells. The fact that AQP-1 was highly expressed at the dural attachment and invading front of meningioma may indicate that dural invasion of the meningioma may be facilitated by AQP-1-induced water flow and neovascularization. [ABSTRACT FROM AUTHOR]

Pituitary carcinomas are very rare. The diagnosis of pituitary carcinoma is defined by evidence of craniospinal and/or systemic metastasis, rather than by histological malignancies. We report a case of prolactin-secreting pituitary macroadenoma invading the cavernous sinuses at the time of initial treatment, which later metastasized to the cerebellum, medulla oblongata, and spinal axis. The patient survived approximately nine years following the initial diagnosis of a pituitary tumor and two years following the diagnosis of metastatic disease. Histological examination of the metastatic cerebellar tumor showed an adenoma with high cellularity and hyperchromasia, but no mitoses. [ABSTRACT FROM AUTHOR]

It is well known that substitutional carbon (C) atoms can capture excess self-interstitial silicon (Si) atoms and suppress the diffusion of ion-implanted interstitial-type dopants, such as boron (B), in Si. In the case of B concentrations as high as ∼1×1021 cm-3, the B activation ratio in Si decreases with C incorporation. Thus, many studies on stable B-containing clusters and/or precipitates in heavily doped Si with a C additive have thus far been conducted. However, the impact of the C incorporation on the activation and clustering of B atoms in Si is yet to be researched. In this work, the chemical bonding features of B and C atoms in heavily B-doped Si with different C contents after high-temperature annealing were characterized systematically by high-resolution X-ray photoelectron spectroscopy (XPS). It was found that the C incorporation enhances B-clustering at B concentrations higher than ∼1×1021 cm-3 after 1050 °C spike annealing. In addition, the formation of C–B bonds with accompanying B-clustering was confirmed by photoemission measurement using a hard X-ray. As a result, the intrinsic B-diffusion was observed to be markedly suppressed by the C incorporation under thermodynamic equilibrium annealing at 1000 °C. [ABSTRACT FROM AUTHOR]

Carbon doped SiGe (SiGe:C)/Si(001) heterostructure were grown by reduced pressure chemical vapor deposition using silane, germane and methylsilane as a source of Si, Ge, and C, respectively. We performed a systematic experiment of growth of SiGe:C and carried out measurements to determine the surface roughness and occupation sites of carbon atoms as functions of C source flow, Ge concentration, growth temperature and growth rate. Ge concentration range was from 0 to 23.0%. Growth temperature was 575 to 625 °C. The range of Growth rate was between 1.5 and 4.3 Å/s. These SiGe:C analyzed by atomic force microscopy (AFM), secondary ion mass spectrometry (SIMS), high-resolution X-ray diffraction (HR-XRD) and cross-sectional transmission electron microscopy (TEM). Total C compositions did not depend on growth temperature with the constant Ge concentration and with SiH3CH3 flow ratio. Surface roughness of SiGe:C with high Ge concentration increased with the increase of C source gas flow. Interstitial C concentration in SiGe:C films with rough surface increased with the increase of C source gas flow. The roughness of SiGe:C layer grown constant C gas source flow ratio decreased for low growth temperature and/or faster growth rate. From these results, we revealed that the mechanism of defect formation with localized C as the cause of rough. The excess migration can suppress surface roughness. [ABSTRACT FROM AUTHOR]

It is well-known that the coimplantation of carbon (C) in a concentration range comparable to the range of boron (B) concentrations could suppress B diffusion, resulting in a boxlike B profile. Substitutional C atoms can capture excess self-interstitial Si atoms and suppress the diffusion of ion-implanted intersitial-type dopants such as B in silicon (Si). However, the effect of C on activation properties in wide C and B concentration ranges has not been sufficiently investigated. In this work, in the experiment in wide C and B concentration ranges, it was clarified for the first time that the B activation ratio of Si increases or decreases varies depending on the concentration of C incorporated. The activation ratio of the B activation layer was increased markedly by C incorporation in the case of light B implantation such as in the concentration range of 8×1019 to 3×1020 cm-3. This might be attributed to the interaction of C with Si interstitials and the suppression of the boron Si-interstitial clustering induced by C incorporation. In contrast, in the case of heavy B implantation such as at a 1×1021 cm-3 concentration, the activation ratio was decreased slightly by C incorporation. When stable B-containing clusters and precipitates were formed at high B concentrations, the effect of C incorporation on activation ratio was considered to be small. [ABSTRACT FROM AUTHOR]

Since the lattice constant of silicon-carbon (Si:C) is smaller than that of Si, Si:C embedded in the source and drain (e-Si:C S/D) can induce tensile stress in the channel and improve the electron mobility of n-metal–oxide–semiconductor field-effect transistor (nMOSFETs). In this research, molecular carbon (C) ion implantation and recrystallization schemes employed to achieve strained Si:C films with a high substitutionally incorporated carbon concentration ([C]sub) and a high ratio of substitution were studied. Several recrystallization techniques including rapid-thermal-annealing (RTA)-based solid phase epitaxy (SPE), spike annealing, and nonmelt laser annealing have been used to optimize C incorporation into Si and strain application. Results of these different implantation and annealing techniques are compared and discussed. Furthermore, we proposed the first recrystallization by nonmelt laser annealing and the co-incorporation of a dopant that increases the rate of Si regrowth and has a covalent radius slightly different from that of Si. These processes markedly promoted the recrystallization of C densely incorporated in an amorphous Si layer and improved the crystallinity of strained Si:C films while maintaining a high [C]sub at a high ratio of substitution. [ABSTRACT FROM AUTHOR]

In conventional self-aligned nickel (Ni) silicide (SALICIDE) process, Ni silicidation is usually carried out by using tungsten–halogen lamp annealing and pn junction leakage current increases with the miniaturization of junction area and depth. The junction leakage is closely related to Ni-silicide thickness determined by absorption coefficient of infrared light from the halogen lamp. We proposed a new method for Ni silicidation based on natural convective heat transfer to the wafer and confirmed that this method can drastically improve the pattern dependence of pn junction leakage because of better uniformity of Ni-silicide thickness independent of pattern size of active areas. [ABSTRACT FROM AUTHOR]

The impacts of source and drain (S/D) doping on device performance in embedded SiGe (e-SiGe) p-channel metal–oxide–semiconductor field-effect transistor (pMOSFET) are presented. An in situ boron-doped e-SiGe S/D device exhibits higher drive current than a boron-implanted e-SiGe S/D device owing to its enhanced hole mobility and reduced parasitic resistance. The precise control of the recessed Si shape and the SiGe proximity to the channel is essential for utilizing the intrinsic benefit of an in situ boron-doped e-SiGe S/D. Moreover, it was confirmed that the channel stress induced by e-SiGe S/D increases as MOSFET size decreases. This indicates that the use of in situ boron-doped e-SiGe S/D is a promising technique for 32 nm node pMOSFET. [ABSTRACT FROM AUTHOR]