Internal Mobile Research Articles

4732865 Self-aligned internal mobile ion getter for multi-layer metallization on integrated circuits

A multi-layer metallization method and structure that permits the use of sodium-ion contaminated titanium-tungsten (Ti:W) as a barrier metal with gold conductor metal on a silicon substrate, without significant degradation of device characteristics. After depositing the barrier and conductor metal layers, a layer of phosphorous-silicate glass (PSG) is anisotropically-etched to expose the field oxide and top surface of the conductor metal but leave PSG layer on each sidewall of the metallization structure. The circuit is then annealed at 400° C. for 30 minutes. Then, an adhesion layer (Si 3 N 4 ) and an insulative layer (SiO 2 ) are deposited over the metallization structure and field oxide, with the adhesion layer in contact with the top surface of the conductor metal and the gettering composition. The resultant circuit has a field threshold voltage shift comparable to devices made without a metal-ion-contaminated barrier layer and the resultant structure reliably retains the PSG layers in contact with the metallization sidewalls.

Photosynthesis in Tall Fescue

Previous work in our laboratory (Krueger, Miles 1981 Plant Physiol 68: 1110-1114) indicated that a decaploid genotype (I-16-2) of tall fescue (Festuca arundinacea Schreb.) which exhibits unusually high net photosynthesis rates also had high potential rates of photosynthetic electron transport through photosystem I (PSI) compared to the typical hexaploid genotype (V6-802). Analysis of electron transport activity revealed that the oxidizing side of PSI as the major site of difference. Examination of the whole thylakoids and subchloroplast particle protein components of the common hexaploid and the decaploid genotypes had major polypeptide differences at 30, 21, and 12.5 kilodaltons. These differences could not be assigned to a specific physiological function in PSI. The decaploid had increased P(700) and plastocyanin content on a chlorophyll basis. Antibodies raised against fescue plastocyanin were used to quantitate plastocyanin in crude (Triton X-100) solubilized extracts of plant material. Results showed that the decaploid had 16% and 40% more plastocyanin on a weight and area basis, respectively. The antibodies did not inhibit electron transport (diaminodiurene to methyl viologen) in isolated thylakoids strengthening the hypothesis of plastocyanin as an internal mobile electron shuttle. The trend of inhibition of plastocyanin by KCN was similar in the two genotypes but the decaploid had 15 to 20% higher rates of electron flow under nearly all inhibiting conditions.

Experimental investigation of the strain rate versus stress dependence in Fe-6at.%Si single crystals

The stress dependence of the strain rate in Fe-6at.%Si single crystals was investigated by means of stress relaxation, strain rate cycling and creep experiments performed at 295 and 475 K. The results obtained by the three techniques are in good agreement with each other and show that the spectrum of localized obstacles to dislocation motion remains essentially unchanged during deformation in the investigated strain range ( γ = 0.04 − 0.60). An analysis of the post-relaxation effects was made and the possible variations in the internal stress and mobile dislocation density during relaxation is discussed.

Interpretation of high temperature plastic deformation in terms of measured effective stresses

The microdynamics of elevated temperature deformation in single and polycrystalline Fe-3 % Si is examined in terms of measured minimum effective stresses. Effective stresses are obtained through the use of a new experimental technique based upon the response of dislocations to the internal and applied stresses. Primary and steady state creep are examined with respect to the measured minimum effective stresses. Modified stress relaxation and strain rate sensitivity techniques are used to study dislocation velocities at elevated temperatures. Dislocation density measurements are made in both steady state creep and stress relaxation experiments and are related to measured effective stresses. Results indicate that the effective stress dependence of the steady state strain rate can be described by e ̇ g3 s ∝ σ min ∗2 where σ min ∗ is the minimum effective stress. Measurements of the tota within the subgrains yielded, p m ∝ σ min ∗ under the assumption that a constant fraction of the total dislocation density within the subgrains is mobile. The indirect measurements of dislocation velocity indicate that at elevated temperatures both the internal stress and mobile dislocation density change reversibly as a unique function of the effective stresses during stress relaxation and strain rate sensitivity tests. Comparison of steady state strain rates with measured dislocation densities supports the assumption of a linear dislocation velocity-effective stress relation.