Modeling of the effect of radicals on plasmas used for etching in microelectronics

Plazma nagrizanje predstavlja jedan od kritičnih koraka u izradi integrisanih kola. Dalja optimizacija plazma uređaja je potrebna jer nove generacije u tehnologiji zahtevaju različitu plazma hemiju. U ovom radu bavimo se uticajem radikala na plazma karakteristike, što je često zanemarivano u plazma modelima. Radikali dominiraju zahvatom elektrona čineći da je bazna smeša za nagrizanje slabo elektronegativna, a oni takođe modifikuju brzinu drifta preko modifikovanog balansa momenta. Mi smo koristili numerička rešenja Bolcmanove jednačine i Monte Karlo simulacije (MCS) za određivanje transportnih koeficijenata elektrona.Plasma etching represents one of the critical steps in manufacturing of integrated circuits. Further optimization of plasma equipment is needed since new generations in technology require different plasma chemistry. In this paper, we will study the influence of radicals on the plasma characteristics, since it was often neglected in plasma models. The radicals dominate attachment of electrons as the basic etching mixture is weakly electronegative and they also affect the drift velocity through modified momentum balance. We have used numerical solutions to the Boltzmann equation and Monte Carlo simulations (MCS) to determine the transport coefficients of electrons

Modeling of the effect of radicals on plasmas used for etching in microelectronics

Plazma nagrizanje predstavlja jedan od kritičnih koraka u izradi integrisanih kola. Dalja optimizacija plazma uređaja je potrebna jer nove generacije u tehnologiji zahtevaju različitu plazma hemiju. U ovom radu bavimo se uticajem radikala na plazma karakteristike, što je često zanemarivano u plazma modelima. Radikali dominiraju zahvatom elektrona čineći da je bazna smeša za nagrizanje slabo elektronegativna, a oni takođe modifikuju brzinu drifta preko modifikovanog balansa momenta. Mi smo koristili numerička rešenja Bolcmanove jednačine i Monte Karlo simulacije (MCS) za određivanje transportnih koeficijenata elektrona.Plasma etching represents one of the critical steps in manufacturing of integrated circuits. Further optimization of plasma equipment is needed since new generations in technology require different plasma chemistry. In this paper, we will study the influence of radicals on the plasma characteristics, since it was often neglected in plasma models. The radicals dominate attachment of electrons as the basic etching mixture is weakly electronegative and they also affect the drift velocity through modified momentum balance. We have used numerical solutions to the Boltzmann equation and Monte Carlo simulations (MCS) to determine the transport coefficients of electrons

Role of pressure in transport of F- ions in BF3 gas for technological applications

U ovom radu predstavili smo transportne parametre dobijene za F- jone u molekularnom gasu BF3 neophodne za formiranje globalnih modela za kompleksne sudarne plazme. Novi rezultati za set preseka i dobijeni transportni koeficijenti za F- jone u BF3 koji se mogu koristiti u takvim modelima su predstavljeni. Prvo smo koristili Nanbu teoriju za određivanje preseka binarnih sudara F- jona sa molekulima BF3. Presek za sudar tri tela uključuje egzotermni binarni presek normiran na izabrani pritisak. Koristili smo Monte Karlo metodu za dobijanje transportnih parametara na temperaturi od T = 295 K i pritisaku od 133.32 Pa (1 Torr).In this work we present swarm data obtained for F- ions in molecular gas BF3 necessary to form the global models for the complex collisional plasmas. The new results for scattering cross section set and proposed transport coefficients for F- ions in BF3 that can be used in such models are presented. First we used Nanbu's theory based on thermodynamic threshold energies to calculate cross sections for binary collisions of Fions with BF3 molecules. Cross section for three body association reaction is included by using exothermic cross section for binary reaction normalized at selected pressure. Monte Carlo method is used to obtain swarm parameters at temperature of T=295 K and pressure of 133.32 Pa (1 Torr)

Role of pressure in transport of F- ions in BF3 gas for technological applications

U ovom radu predstavili smo transportne parametre dobijene za F- jone u molekularnom gasu BF3 neophodne za formiranje globalnih modela za kompleksne sudarne plazme. Novi rezultati za set preseka i dobijeni transportni koeficijenti za F- jone u BF3 koji se mogu koristiti u takvim modelima su predstavljeni. Prvo smo koristili Nanbu teoriju za određivanje preseka binarnih sudara F- jona sa molekulima BF3. Presek za sudar tri tela uključuje egzotermni binarni presek normiran na izabrani pritisak. Koristili smo Monte Karlo metodu za dobijanje transportnih parametara na temperaturi od T = 295 K i pritisaku od 133.32 Pa (1 Torr).In this work we present swarm data obtained for F- ions in molecular gas BF3 necessary to form the global models for the complex collisional plasmas. The new results for scattering cross section set and proposed transport coefficients for F- ions in BF3 that can be used in such models are presented. First we used Nanbu's theory based on thermodynamic threshold energies to calculate cross sections for binary collisions of Fions with BF3 molecules. Cross section for three body association reaction is included by using exothermic cross section for binary reaction normalized at selected pressure. Monte Carlo method is used to obtain swarm parameters at temperature of T=295 K and pressure of 133.32 Pa (1 Torr)

Self-aggregation of soil humic acids with respect to their structural characteristics

The main goal of this work was to estimate the influence of carboxyl and phenolic groups, as well as aromatic, aliphatic and polysaccharide components, on the soil humic acids (HA) self-aggregation process. Soil HAs (leptosol and regosol) were separated using base resin getting fractions with different functional group contents. Blocking of carboxyl groups was performed using the esterification procedure to estimate the participation of each functional group in the HA aggregation. The presence of HA structural components was evaluated by potentiometric titration and ATR-FTIR. The aggregation was monitored at pH 3 using dynamic light scattering. Results indicated that the higher group content, the HA aggregation is less pronounced. A significant positive correlation of aliphatic C and aggregate size revealed their dominant influence in the HA self-aggregation. A lower abundance of aliphatic C in HA fractions could be considered as not sufficient to start the process. An increase of aromatic C in esters likely pointed out to its participation in hydrophobic bonding and, consequently, more pronounced aggregation. The relation of HA self-aggregate size with carboxyl and phenolic group, as well as aliphatic C, at low pH, could be considered universal regardless of the structural characteristics of the original or modified HA forms

Hyperbaric oxygenation in prevention of amputations of diabetic foot

Background/Aim. Diabetic foot is the term for the pathological changes on foot in patients with diabetes. It is caused by diabetic angiopathy, polyneuropathy and osteoarthropathy. The treatment is complex and long-term and often leads to the loss of the extremity. The appliance of hyperbaric oxygen therapy (HBOT) has a lot more important place in adjuvant treatment of this disease. The aim of this study was to determine the influence of HBOT on the wound healing in comparison with the conventional treatment, the possibility of shortening the time of the treatment in patients with diabetic foot. Methods. In a five-year period a retrospective-prospective multicentric study, involving 60 patients with diabetic foot divided into two groups, was performed. The first group (group A) consisted of 30 patients treated by combined therapy (with medications, surgical therapy and HBOT). All the patients were receiving HBOT in the Special Hospital for Hyperbaric Medicine, CHM Hollywell-Neopren in Belgrade. The control group (group B) also consisted of 30 patients treated with medications and surgical therapy, but without HBOT. Results. The demographic data, the types of diabetes, as well as the Wagner classification stage of diabetic ulcers and radiography scans of changes in bones were equal in both groups. The median healing time of the Wagner grade III ulcer in the group A was 37.36 days [mean +/- standard deviation (SD) = 65.6 +/- 45.8 days], and in the group B 99.78 days (mean +/- SD = 134.8 +/- 105.96 days) and it was statistically significant (p = 0.074). The median time of recovery in patients of the group A with the Wagner grade IV was 48.18 days (mean +/- SD = 49.7 +/- 33.8 days), and in the group B 85.05 days (mean +/- SD = 86.7 +/- 71.6 days) and that was statistically significant (p = 0.121). The foot amputations were performed in both groups in 3 (10%) patients. In the group A there were no high amputations, whereas in the group B there were 4 (13.33%) below-knee amputations and 4 (13.33%) above-knee amputations which was highly statistically significant (p lt 0.0001). Conclusion. In this study, HBOT definitely showed positive adjuvant role in the treatment of diabetic foot. For the good treatment result it is essential the timely and successful surgical treatment of the ulcer and the use of bandage with the healing dressings. In case of the clear signs of local infection, the antibiotic therapy according to the antibiogram is necessary

Self-aggregation of soil humic acids with respect to their structural characteristics

The main goal of this work was to estimate the influence of carboxyl and phenolic groups, as well as aromatic, aliphatic and polysaccharide components, on the soil humic acids (HA) self-aggregation process. Soil HAs (leptosol and regosol) were separated using base resin getting fractions with different functional group contents. Blocking of carboxyl groups was performed using the esterification procedure to estimate the participation of each functional group in the HA aggregation. The presence of HA structural components was evaluated by potentiometric titration and ATR-FTIR. The aggregation was monitored at pH 3 using dynamic light scattering. Results indicated that the higher group content, the HA aggregation is less pronounced. A significant positive correlation of aliphatic C and aggregate size revealed their dominant influence in the HA self-aggregation. A lower abundance of aliphatic C in HA fractions could be considered as not sufficient to start the process. An increase of aromatic C in esters likely pointed out to its participation in hydrophobic bonding and, consequently, more pronounced aggregation. The relation of HA self-aggregate size with carboxyl and phenolic group, as well as aliphatic C, at low pH, could be considered universal regardless of the structural characteristics of the original or modified HA forms

Microstructure and Properties of Gravity Sintered 316L Stainless Steel Powder with Nickel boride Addition

The present work demonstrates a procedure for synthesis of stainless steel powder by gravity sintering method. As an additive to the basic powder, NiB powder was added in the amount of 0.2 - 1.0 wt.%. Gravity sintering was done in vacuum, at the temperatures of 1100 degrees C - 1250 degrees C, in the course of 3 - 60 min, using ceramic mould. Structural characterization was conducted by XRD, and microstructural analysis by optical and scanning electron microscope (SEM). Mechanical properties were investigated by tensile tests with steel rings. Density and permeability were determined by standard techniques for porous samples. Gravity sintered stainless steel with NiB addition had more superior mechanical and physico-chemical properties compared to stainless steel obtained by standard powder metallurgy procedures - pressing and sintering

Properties of humic acids from copper tailings 20 years after reclamation

Part of Cu post flotation tailings of Serbia ZiJin Bor Copper, Serbia, was reclaimed by restoration of top soil with arable soils, and revegetation in 1991. Humic acids isolated from these Technosols were investigated to find out if their properties underwent any changes since reclamation. Two groups of control samples were used. Elemental composition (CHNS analysis) falls within the range of average soil humic acids. Humic acids belong to the type B pointing out to its lower humification degree (UV?Vis). Relative abundances of functional groups are ranged as follows: polysaccharide C ??aromatic C > carboxyl C > OH group > aliphatic C. Aromaticity indexes are low, 1.88? 3.25 (ATR-FTIR). Basic units at pH 10 are in the 11.7?26.8 nm range. Pronounced reaggregation (1462-?5218 nm) at pH 3 points out to less expressed humic acid sol stability, as well as to increase in aromatic condensation degree (dynamic light scattering). No significant changes have occurred in technosol humic acids since the recultivation, confirming stability of their properties over time (PCA). Nevertheless, humic acids from very strongly acidic Technosols show higher humifycation degree possibly originating from arable soils used in reclamation, but more likely from low soil pH and low litter input, results of unsuccessful reclamation

Removal of Cs Ions from Aqueous Solutions by Using Matrices of Natural Clinoptilolite and its Safe Disposal

The possibility to use natural zeolite - clinoptilolite as a host material for radioactive Cs immobilization has been investigated. Cs-exchanged form of clinoptilolite which was prepared by treatment of clinoptilolite powder with 0.25 M CsCl solution was compacted. Both, powder and powder compact of exchanged clinoptilolite were thermally treated at 1200 C-0. The XRPD analysis showed that Cs was successfully immobilized after heat treatment by formation of stable cesium dodecaoxo-alumopentasilicate in both, powder sample and compact. The newly formed compound showed satisfactory Cs ions retention during leaching test. The sintered compact showed somewhat better resistance to Cs leaching than the thermally treated powder. The compressive strength of sintered compact was close to 200 MPa which is more than enough for easy handling and safe storage