We have developed a process for forming an ultra-thin HfSiOx interfacial layer (HfSiOx-IL) for high-k gate stacks. The HfSiOx-IL was grown by the solid-phase reaction between HfO2 and Si-substrate ...performed by repeating the sequence of ALD HfO2 deposition and RTA. The HfSiOx-IL grown by this method enables the formation of very uniform films consisting of a few mono-layers, and the dielectric constant of the HfSiOx-IL is about 7. The FUSI-NiSi/HfO2 gate stacks with HfSiOx-IL have achieved 0.6 nm EOT, a very low gate leakage currents between 1 A/cm2 and 5X10-2 A/cm2, an excellent subthreshold swing of 66mV/dec, and a high peak mobility of 160 cm2/Vs compared to the reference samples without HfSiOx-IL. These results indicate that the HfSiOx-IL has a good quality compared to the SiO2 interfacial layer grown by oxygen diffusion through HfO2 films.
The clinical significance of adenomyomatosis of the gallbladder remains unclear. This study aimed to clarify the relationship between segmental adenomyomatosis and gallbladder carcinoma, and to ...elucidate the histogenesis of gallbladder carcinoma associated with segmental adenomyomatosis. A total of 4,560 consecutive patients underwent cholecystectomy. The specimens were examined grossly and histologically. Adenomyomatosis of the gallbladder was divided into segmental, fundal, and diffuse types. Sixty noncancerous gallbladders with segmental adenomyomatosis were examined for epithelial metaplasia. The incidence of gallbladder carcinoma was higher in patients with segmental adenomyomatosis (22/334, 6.6%) than in those without (181/4226, 4.3%; P=0.049). This difference was more marked among patients equal to or older than 60 years of age (15/96,15.6% versus 147/2407, 6.1%, respectively; P<0.001). The other types of adenomyomatosis did not show any significant increases in the incidence of gallbladder carcinoma. In all 22 patients with both segmental adenomyomatosis and carcinoma, the tumors developed only in the fundal mucosa. Epithelial metaplasia was more marked in the fundal mucosa of segmental adenomyomatosis than in the neck mucosa (P=0.003). Segmental adenomyomatosis is a high-risk condition for gallbladder carcinoma, especially in elderly patients. Epithelial metaplasia appears to be related to increased carcinogenesis in the fundal mucosa of segmental adenomyomatosis.
To identify the neural correlates for impaired performance on the clock drawing test (CDT) in patients with Alzheimer's disease (AD), we examined the relationship between the CDT performances and the ...regional cerebral blood flow (rCBF) in 100 AD patients. The patients were equally divided into a mildly impaired CDT group, a severely impaired CDT group, and two normal CDT groups, with age and dementia severity matched. Between-group comparisons revealed that rCBF reduction in the posterolateral region of the left temporal lobe was consistently associated with mild to severe impairment of the CDT in AD. Correlation analysis also showed that the rCBF in the left posterolateral temporal cortex was linearly correlated with CDT performance. The CDT scores in AD were significantly improved for the copy condition relative to the drawing-to-command condition. These findings suggest that CDT performance has a close relationship with the left posterior temporal function, and that semantic memory deficit may at least partly contribute to impaired CDT performance in AD.
To evaluate the possible relation between the rate of cognitive deterioration in patients with probable Alzheimer's disease (AD) and the distribution pattern of neural dysfunction.
The regional ...cerebral blood flow (rCBF) was measured in rapidly and slowly progressing groups of AD patients using single-photon emission computed tomography and was compared between the groups. While controlling for demographic and clinical factors that could be associated with the stage and prognosis of the illness, the deterioration rate of the Mini Mental State Examination (MMSE) score was significantly greater in the rapidly progressing group than that in the slowly progressing group.
The rCBF in the right posterodorsal, anterior and superior prefrontal cortices and the inferior parietal cortex was significantly lower in the rapidly progressing patients. Moreover, lower perfusion in these regions correlated significantly with rapid deterioration in the MMSE.
These findings suggest that the rCBF values in these cortical regions could be useful in predicting which AD patients will show a relatively rapid cognitive decline.
In order to explore the factor structure of a modified version of the Wisconsin Card Sorting Test (mWCST) and to identify the dimensions of deficit in patients with Alzheimer's disease (AD) and mild ...cognitive impairment (MCI), conventional mWCST scores in 55 AD patients, 17 MCI patients, and 22 controls were subjected to factor analysis. Three factors, perseveration, inefficient sorting, and nonperseverative error, were obtained. Perseveration score was significantly poorer in both AD and MCI than in controls. By contrast, the MCI group showed significantly poorer scores on the nonperseverative error factor than did the AD patients, and the controls yielded intermediate values between the two patient groups. The perseveration factor was significantly correlated with the other estimates of executive function. This study suggested that the many mWCST scores could be reduced to three major factors, and that the perseveration score may effectively represent an aspect of executive dysfunction in AD and MCI patients.
We studied the effect of post-deposition annealing on a HfO
2/Si interface of by extremely asymmetric X-ray diffraction.
Comparing the rocking curves before annealing the sample with those of the ...annealed sample, it is found that an interfacial layer with a density of 3
g/cm
3 grows at the interface between the HfO
2 layer and the substrate during post-deposition annealing. The wavelength dependency of the integrated intensities of the rocking curve for the as-deposited sample fluctuated with the observation position. This fluctuation was suppressed by annealing. From these results we concluded that the strain introduced into the substrate becomes homogeneous by annealing. Moreover, a quantitative estimation of the strain by curve fitting reveals the existence of compressive strain under the HfO
2 layer.
Platinum thin films grown by chemical vapor deposition (CVD) using a liquid precursor of (methylcyclopentadienyl)trimethylplatinum were characterized in terms of crystallographic nature, morphology, ...contaminants, and their influence on electrical properties. The lattice constant of these CVD films (3.91–3.92 Å) is smaller than that of bulk platinum. A high oxygen contaminant is observed, irrespective of the oxygen ratio during growth. A film grown at low oxygen content consists of randomly oriented micro-grains and contains a large amount of carbon contaminants. When the film is grown under oxidative conditions, it shows a 111-textured cylindrical morphology with increasing thickness. The electric resistivity is higher than the bulk standard, and it increases with decreasing oxygen ratio during the film growth. These results indicate that the carbon contaminant causes the randomly oriented micro-grains and contributes to the high residual resistivity.
Effective work function (m,eff) values of Hfx Ru1-x alloy gate electrodes on SiO2 metal-oxide-semiconductor (MOS) capacitors were carefully examined to assess whether the m,eff was determined by the ...crystalline structure or the composition of the HfxRu1-x alloy. X-ray diffraction results indicated that the crystalline structures of HfxRu1-x alloy were divided into hexagonal-Ru, cubic-HfRu or hexagonal-Hf with the increase of Hf content. The m,eff values could be controlled continuously from 4.6 to 4.0 eV by changing the Hf content. The experimental m,eff value showed a good agreement with theoretical results considering the compositional ratio of pure Hf and Ru. These results suggest that the m,eff of HfxRu1-x alloy gates on SiO2 MOS capacitors is dominantly determined by the HfxRu1-x composition rather than the crystalline structure.
