We demonstrated the operation of phase-change memory cells that enabled 1.

The decomposition process of tetraethylorthosilicate (TEOS) and ozone at atmospheric pressure was measured in a closed vessel by in-situ Fourier-transform infrared absorption (FT-IR) analysis, and the changes of the deposition rate and the overall sticking probability β of the film precursor were obtained along the flow direction in a flow-type reactor. It has been found that the film precursors are formed by TEOS decomposition with O-atoms and/or ozone in the gas phase, and that CH3CHO may be the first product, followed by the oxidation to CO2 and H2O via HCHO. It is also shown that the film quality changes along the flow direction, that is, O-H bonds in the film decrease and the β-value increases as the reaction proceeds. These results may show that there are several kinds of precursors, and the sticky (unstable) precursors become dominant in the later stages.

One rhesus macaque displayed severe encephalomyelitis and another displayed severe enterocolitis following infection with molecularly cloned simian immunodeficiency virus (SIV) strain SIVmac239. Little or no free anti-SIV antibody developed in these two macaques, and they died relatively quickly (4 to 6 months) after infection. Manifestation of the tissue-specific disease in these macaques was associated with the emergence of variants with high replicative capacity for macrophages and primary infection of tissue macrophages. The nature of sequence variation in the central region (vif, vpr, and vpx), the env gene, and the nef long terminal repeat (LTR) region in brain, colon, and other tissues was examined to see whether specific genetic changes were associated with SIV replication in brain or gut. Sequence analysis revealed strong conservation of the intergenic central region, nef, and the LTR. However, analysis of env sequences in these two macaques and one other revealed significant, interesting patterns of sequence variation. (i) Changes in env that were found previously to contribute to the replicative ability of SWVmac for macrophages in culture were present in the tissues of these animals. (ii) The greatest variability was located in the regions between VI and V2 and from "V3" through C3 in gpl20, which are different in location from the variable regions observed previously in animals with strong antibody responses and long-term persistent infection. (iii) The predominant sequence change of D-N at position 385 in C3 is most surprising, since this change in both SIV and human immunodeficiency virus type 1 has been associated with dramatically diminished affinity for CD4 and replication in vitro. (iv) The nature of sequence changes at some positions (146, 178, 345, 385, and "V3") suggests that viral replication in brain and gut may be facilitated by specific sequence changes in env in addition to those that impart a general ability to replicate well in macrophages. These results demonstrate that complex selective pressures, including immune responses and varying cell and tissue specificity, can influence the nature of sequence changes in env.

Electrical properties of (Ba, Sr)TiO3 [BST] films have been investigated on RuO2/Ru and Ru electrodes instead of Pt, because they are easy to be etched. BST films were deposited at a substrate temperature of T s=420° C and a reactor pressure of P=1.5 Torr by employing a two-step liquid source chemical vapor deposition (CVD) process. BST films on RuO2/Ru were electrically shorted, which was considered to be caused by surface roughening during BST film deposition and/or post-annealing. In the case of Ru electrodes, an equivalent SiO2 thickness of t eq=0.50 nm (a dielectric constant of ε r=190), a leakage current of J L=4.6×10-8 A/cm2 at +1.1 V, and a dielectric loss of tan δ=0.018 were achieved at a total film thickness of 250 Å, by restricting Ru surface oxidation and its surface roughening. Moreover, BST film deposition on Ru storage nodes, 0.24 µ m wide, 0.6 µ m deep, 0.15 µ m high, and each spaced by 0.3–0.14 µ m, verified that the storage capacitance can be successfully increased by using sidewalls of the storage node, without a significant increase in the leakage current.

Protrusions of (Ba, Sr)TiO3 (BST) crystallites were found to appear on BST film surfaces prepared by liquid source chemical vapor deposition (CVD) at a substrate temperature T s=420° C and a reactor pressure P=1.5 Torr. Such protrusions were successfully suppressed by two-step deposition, where BST films consisted of a buffer layer and a main layer; the buffer layer was a CVD-BST film about 60 Å thick annealed in N2 ambient. By this two-step deposition on Pt electrodes, the BST film properties of equivalent SiO2 thickness t eq=0.56 nm, leakage current J L=1.2×10-8 A/cm2 at +1.1 V and dielectric loss tan δ=0.011 were achieved at a total film thickness of 230 Å, along with a coverage of 80% at a trench of aspect ratio 0.65 and sufficiently low absorption current.