Calibration of MEMS-based test structures for predicting thermomechanical stress in integrated circuit interconnect structures

This paper uses a rotating-beam-sensor structure to show that the extrinsic stress from the mismatch in expansion coefficient between the aluminum and the silicon substrate dominates over the compressive stress from the sputter growth. Sintering the layers at temperatures above 150/spl deg/C reduces this compressive stress due to the action of creep. Calibration of the rotation of the device has been undertaken by direct comparison to high resolution X-ray-diffraction measurements and these show that the sensor has a resolution better than 2.8 MPa. Furthermore, we have used the sensor to investigate the variation of in-plane stress with the compliance of the intermetal dielectric, by directly comparing sensors fabricated on SiO/sub 2/ and polyimide layers.     

Effect of protein malnutrition on the glycolytic and glutaminolytic enzyme activity of rat thymus and mesenteric lymph nodes

Genotyping of hepatitis C virus (HCV) of liver disease patients in the Dominican Republic was performed. Eighty-four samples positive for HCV antibody, which were confirmed by ELISA, particle agglutination, and recombinant immunoblot assay III tests, were subjected to HCV genotyping by polymerase chain reaction using type-specific primers located in the nonstructural protein 5 region. Of the 84 samples tested, 50 (59%) were found to have genotype 1a/I and this genotype was the most frequent type detected in the present study. The numbers of isolates of genotypes 1b/II, 2a/III, 2b/IV, and 3a/V were three (3.6%) six (7.1%), two (2.4%), and two 2.4%), respectively. The number of samples having mixed genotype populations was 16 (19%). The possible causes of the high prevalence of genotype 1a/I in the Dominican Republic compared with other countries and of the high detection ratio of samples having mixed genotypes are discussed.     

Spherical particles of phenolic resin treated with iron oxide

This paper describes the preparation and characterization of phenolic resins’ thermospheres covered by a magnetic phase of iron oxide. The thermospheres were prepared by allowing phenol and formaldehyde to react under dispersion polymerization conditions and the iron oxide phase was incorporated in situ onto the phenolic resin particles by adding concentrated NH₃ to FeCl₂ in DMSO. This reaction was conducted at 70 °C under nitrogen atmosphere in a controlled temperature vessel, and the modified resin was isolated and dried in vacuo. Both pure and modified resins were characterized by DRX, TG-DTA, and MEV/EDX. The modified particles were attracted by a magnetic field, indicating the fixation of magnetic iron oxide. No diffraction peaks were observed in DRX analysis; thermal analysis (DTA) of both pure and modified resins presented exothermic events between 300 and 680 °C, and 300 and 570 °C, respectively, indicating the microstructure of the resin was modified after the treatment. Thermogravimetric analysis (TGA) of the pure resin registered a 2.0% residue, compared to 8.0% for the modified resin. These residues correspond to about 7.0% of fixed iron oxide. MEV/EDX analyses confirm the modification of the resins by the process of fixing iron oxide.     

Dependence of process parameters on stress generation in aluminum thin films

The dependence of residual stress on the process parameters for aluminum metallization has been studied using a rotating beam sensor. This shows increasing tensile stress with both the target power and ambient pressure used during the sputter deposition of the aluminum layer. The bulk resistivity of the deposited aluminum has been measured using a Van der Pauw technique on test structures fabricated alongside the sensors and this shows different trends with respect to the target power and ambient pressure. This indicates that the stress in an interconnect feature is dominated by extrinsic components, which result from the mismatch in thermal expansion coefficient between the constituent layers, rather than the defects formed during the sputter deposition of the metallization. This indicates the suitability of the stress sensor technique to the monitoring of interconnect features in a production line environment.     

Acute extracellular fluid volume changes increase ileocolonic resistance to saline flow in anesthetized dogs

We determined the effect of acute extracellular fluid volume changes on saline flow through 4 gut segments (ileocolonic, ileal, ileocolonic sphincter and proximal colon), perfused at constant pressure in anesthetized dogs. Two different experimental protocols were used: hypervolemia (iv saline infusion, 0.9% NaCl, 20 ml/min, volume up to 5% body weight) and controlled hemorrhage (up to a 50% drop in mean arterial pressure). Mean ileocolonic flow (N = 6) was gradually and significantly decreased during the expansion (17.1%, P < 0.05) and expanded (44.9%, P < 0.05) periods while mean ileal flow (N = 7) was significantly decreased only during the expanded period (38%, P < 0.05). Mean colonic flow (N = 7) was decreased during expansion (12%, P < 0.05) but returned to control levels during the expanded period. Mean ileocolonic sphincter flow (N = 6) was not significantly modified. Mean ileocolonic flow (N = 10) was also decreased after hemorrhage (retracted period) by 17% (P < 0.05), but saline flow was not modified in the other separate circuits (N = 6, 5 and 4 for ileal, ileocolonic sphincter and colonic groups, respectively). The expansion effect was blocked by atropine (0.5 mg/kg, i.v.) both on the ileocolonic (N = 6) and ileal (N = 5) circuits. Acute extracellular fluid volume retraction and expansion increased the lower gastrointestinal resistances to saline flow. These effects, which could physiologically decrease the liquid volume being supplied to the colon, are possible mechanisms activated to acutely balance liquid volume deficit and excess.