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EUV mask surface cleaning effects on lithography process performance

Description: The reflective, multilayer based, mask architectures for extreme ultraviolet (EUV) lithography are highly susceptible to surface oxidation and contamination. As a result, EUV masks are expected to undergo cleaning processes in order to maintain the lifetimes necessary for high volume manufacturing. For this study, the impact of repetitive cleaning of EUV masks on imaging performance was evaluated. Two, high quality industry standard, EUV masks are used for this study with one of the masks undergoing repeated cleaning and the other one kept as a reference. Lithographic performance, in terms of process window analysis and line edge roughness, was monitored after every two cleans and compared to the reference mask performance. After 8x clean, minimal degradation is observed. The cleaning cycles will be continued until significant loss imaging fidelity is found.
Date: June 18, 2010
Creator: George, Simi; Baclea-an, Lorie Mae; Naulleau, Patrick; Chen, Robert J. & Liang, Ted
Partner: UNT Libraries Government Documents Department

Process-Based Quality Tools to Verify Cleaning and Surface Preparation

Description: A test method, the Tensile Brazil Nut Sandwich (TBNS) specimen, was developed to measure mixed-mode interfacial toughness of bonded materials. Interfacial toughness measured by this technique is compared to the interfacial toughness of thin film adhesive coatings using a nanoindentation technique. The interfacial toughness of solvent-cast and melt-spun adhesive thin films is compared and found to be similar. Finally, the Johnson-Kendall-Roberts (JKR) technique is used to evaluate the cleanliness of aluminum substrates.
Date: May 1, 2003
Creator: EMERSON, JOHN A.; GIUNTA, RACHEL K.; REEDY JR., EARL DAVID; ADAMS, DAVID P.; LEMKE, PAUL ALBERT & MOODY, NEVILLE R.
Partner: UNT Libraries Government Documents Department

Optical performance of the TBC-2 solar collector before and after the 1993 mirror lustering

Description: In 1993, the mirror facets of one of Sandia`s point-focusing solar collectors, the Test Bed Concentrator {number_sign}2 (TBC-2), were reconditioned. The concentrator`s optical performance was evaluated before and after this operation. This report summarizes and compares the results of these tests. The tests demonstrated that the concentrator`s total power and peak flux were increased while the overall flux distribution in the focal plane remained qualitatively the same.
Date: February 1, 1995
Creator: Houser, R. & Strachan, J.
Partner: UNT Libraries Government Documents Department

Contamination and uniformity control in plasma processing tools

Description: This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). We have collaborated with industry to build a laboratory to study plasma processing, a surface-cleaning technique that uses short-lived, gaseous reactants in place of chemical solvents. We have performed experiments and developed computer models to understand how complex substrate geometries affect plasma electrical properties and to demonstrate the feasibility of generating metastable molecular oxygen in a plasma.
Date: October 1, 1996
Creator: Selwyn, G.; Brackbill, J.; Jones, M. & Winske, D.
Partner: UNT Libraries Government Documents Department

Preparation of GaAs photocathodes at low temperature

Description: The preparation of an atomically clean surface is a necessary step in the formation of negative electron affinity (NEA) GaAs. Traditional methods to this end include cleaving, heat cleaning and epitaxial growth. Cleaving has the advantage of yielding a fresh surface after each cleave, but is limited to small areas and is not suitable for specialized structures. Heat cleaning is both simple and highly successful, so it is used as a preparation method in virtually all laboratories employing a NEA source on a regular basis. Due to its high cost and complexity, epitaxial growth of GaAs with subsequent in vacuo transfer is not a practical solution for most end users of GaAs as a NEA electron source. While simple, the heating cleaning process has a number of disadvantages. Here, a variety of cleaning techniques related to preparation of an atomically clean GaAs surface without heating to 600 C are discussed and evaluated.
Date: October 1, 1996
Creator: Mulhollan, G.; Clendenin, J. & Tang, H.
Partner: UNT Libraries Government Documents Department

Atomic hydrogen cleaning of semiconductor photocathodes

Description: Negative Electron Affinity (NEA) semiconductor photocathodes are widely used for the production of polarized electron beams, and are also useful for the production of high brightness electron beams which can be modulated at very high frequencies. Preparation of an atomically clean semiconductor surface is an essential step in the fabrication of a NEA photocathode. This cleaning step is difficult for certain semiconductors, such as the very thin materials which produce the highest beam polarization, and those which have tightly bound oxides and carbides. Using a small RF dissociation atomic hydrogen source, the authors have reproducibly cleaned GaAs wafers which have been only degreased prior to installation in vacuum. They have consistently prepared very high quantum efficiency photocathodes following atomic hydrogen cleaning. Details of their apparatus and most recent results are presented.
Date: June 1, 1997
Creator: Sinclair, C. K.; Poelker, B. M. & Price, J. S.
Partner: UNT Libraries Government Documents Department

Acceptance Test Report for the high pressure water jet system canister cleaning fixture

Description: This Acceptance Test confirmed the test results and recommendations, documented in WHC-SD-SNF-DTR-001, Rev. 0 Development Test Report for the High Pressure Water Jet System Nozzles, for decontaminating empty fuel canisters in KE-Basin. Optimum water pressure, water flow rate, nozzle size and overall configuration were tested
Date: October 25, 1995
Creator: Burdin, J.R.
Partner: UNT Libraries Government Documents Department

Corrosion resistance of inconel 690 to borax, boric acid, and boron nitride at 1100{degrees}C

Description: Significant general and localized corrosion was observed on Inconel 690 coupons following exposure to borax, boric acid and boron nitride at 1100{degrees}C. Severe localized attack at and below the melt line was observed on coupons exposed to borax. An intergranular attack at and below the melt line was observed on coupons exposed to borax. An intergranular attack (IGA) of the Inconel 690 was also observed. Severe internal void formation and IGA (30 mils penetration after 3 days) was observed in the coupon exposed to boric acid. Both borax and boric acid remove the protective chromium oxide; however, this layer can be reestablished by heating the Inconel 690 to 975 {degrees}C in air for several hours. Inconel 690 in direct contact with boron nitride resulted in the formation of a thick chromium borate layer, a general corrosion rate of 50 to 90 mils per year, and internal void formation of 1 mil per day.
Date: December 12, 1996
Creator: Imrich, K. J.
Partner: UNT Libraries Government Documents Department

Exposure of GaAs to atomic hydrogen for cleaning prior to NEA photocathode activation

Description: Creating an atomically clean semiconductor surface is an essential step in preparing negative electron affinity (NEA) photoemission cathodes. While bulk GaAs can be satisfactorily cleaned by chemical etching and in situ heat cleaning, many high polarization electron source materials are either much too thin, or have oxides and carbides which are too tightly bound, to be cleaned by these methods. Some polarized source candidate materials may be degraded during the heat cleaning step. It is well established that the exposure of many III-V, II-VI, and elemental semiconductors to atomic hydrogen, typically at elevated temperatures, produces semiconductor surfaces free of contamination. Furthermore, this cleaning, possibly followed by thermal annealing, leaves surfaces which show sharp LEED patterns, indicating good stoichiometry and surface order. Atomic hydrogen cleaning should eliminate the chemical etching step, and might reduce the temperature and/or temperature-time product presently used in forming NEA cathodes. The process is readily adaptable to in situ use in ultrahigh vaccum.
Date: December 31, 1998
Creator: Sinclair, C.K.; Poelker, B.M. & Price, J.S.
Partner: UNT Libraries Government Documents Department

Tritium retention and removal on TFTR

Description: Tritium retention and removal are critical issues for the success of ITER or any DT fusion reactor. The Tokamak Fusion Test Reactor, TFTR, is the first fusion facility to afford the opportunity to study the tritium retention and removal over an extended period. In TFTR, tritium accumulates on all surfaces with line of sight to the plasma by codeposition of tritium with carbon. Measurements of both deuterium and tritium retention fractions have yielded retention between 0.2 and 0.6 of the injected fuel in the torus. Tritium has been successfully removed from TFTR by glow discharge cleaning and by air purges. The in-vessel inventory was reduced by a factor of 2, facilitating machine maintenance. In TFTR, the amount of dust recovered from the TFTR vacuum vessel has varied from several grams to a few kilograms.
Date: November 1, 1997
Creator: Mueller, D.; Blanchard, W. & Doyle, B.L.
Partner: UNT Libraries Government Documents Department

Assessment of surface contamination with contact mechanics

Description: The authors are particularly interested in the work of adhesion measurements as a means to facilitate the understanding of the adhesive failure mechanisms for systems containing encapsulated and bonded components. Of the several issues under investigation, one is the effect of organic contamination on the adhesive strength for several types of polymer/metal interface combinations. The specific question that the authors are trying to address is at what level of contamination does adhesive strength decrease. The use of contact mechanics, the JKR method, is a good approach for studying this question. Another approach being studied is the use of interracial fracture mechanics. The model contaminant is hexadecane--non-polar, medium molecular weight hydrocarbon fluid. They choose hexadecane because it replicates typical machining fluids, is nonreactive with Al surfaces, and should not dissolve readily into the adhesive systems of interest. The application of a uniform, controllable and reproducible hexadecane layer on Al surfaces has proven to be difficult. A primary concern is whether studies of model systems can be extended to systems of technological interest. The JKR theory is a continuum mechanics model of contact between two solid spheres that was developed by Johnson, Kendall and Roberts. The JKR theory is an extension of Hertzian contact theory and attributes the additional increase in the contact area between a soft elastomeric hemisphere to adhesive forces between the two surfaces. The JKR theory allows a direct estimate of the surface free energy of interface as well as the work of adhesion (Wa) between solids. Early studies performed in this laboratory involved the determination of Wa between silicone (PDMS) and Al surfaces in order to establish the potential adhesive failure mechanisms. However, the JKR studies using commercial based PDMS [poly(dimethylsiloxane)] was fraught with difficulty that were attributed to the additives used in commercial PDMS systems. The authors ...
Date: February 21, 2000
Creator: EMERSON,JOHN A.; MILLER,GREGORY V.; SORENSEN,CHRISTOPHER R. & PEARSON,RAYMOND A.
Partner: UNT Libraries Government Documents Department

Investigation of the impact of cleaning on the adhesive bond and the process implications

Description: While surface cleaning is the most common process step in DOE manufacturing operations, the link between a successful adhesive bond and the surface clean performed before adhesion is not well understood. An innovative approach that combines computer modeling expertise, fracture mechanics understanding, and cleaning experience to address how to achieve a good adhesive bond is discussed here to develop a capability that would result in reduced cleaning development time and testing, improved bonds, improved manufacturability, and even an understanding that leads to improved aging. A simulation modeling technique, polymer reference interaction site model applied near wall (Wall PRISM), provided the capability to include contaminants on the surface. Calculations determined an approximately 8% reduction in the work of adhesion for 1% by weight of ethanol contamination on the structure of a silicone adhesive near a surface. The demonstration of repeatable coatings and quantitative analysis of the surface for deposition of controlled amounts of contamination (hexadecane and mineral oil) was based on three deposition methods. The effect of the cleaning process used on interfacial toughness was determined. The measured interfacial toughness of samples with a Brulin cleaned sandblasted aluminum surface was found to be {approximately} 15% greater than that with a TCE cleaned aluminum surface. The sensitivity of measured fracture toughness to various test conditions determined that both interfacial toughness and interface corner toughness depended strongly on surface roughness. The work of adhesion value for silicone/silicone interface was determined by a contact mechanics technique known as the JKR method. Correlation with fracture data has allowed a better understanding between interfacial fracture parameters and surface energy.
Date: May 1, 2000
Creator: EMERSON,JOHN A.; GUESS,TOMMY R.; ADKINS,CAROL L. JONES; CURRO,JOHN G.; REEDY JR.,EARL DAVID; LOPEZ,EDWIN P. et al.
Partner: UNT Libraries Government Documents Department

Precision Cleaning Titanium Components

Description: Clean bond surfaces are critical to the operation of diffusion bonded titanium engine components. These components can be contaminated with machining coolant, shop dirt, and fingerprints during normal processing and handling. These contaminants must be removed to achieve acceptable bond quality. As environmental concerns become more important in manufacturing, elimination of the use of hazardous materials is desired. For this reason, another process (not using nitric-hydrofluoric acid solution) to clean titanium parts before bonding was sought. Initial cleaning trials were conducted at Honeywell to screen potential cleaning techniques and chemistries. During the initial cleaning process screening phase, Pratt and Whitney provided Honeywell with machined 3 inch x 3 inch x 1 inch titanium test blocks. These test blocks were machined with a water-based machining coolant and exposed to a normal shop environment and handling. (Honeywell sectioned one of these blocks into smaller samples to be used for additional cleanliness verification analyses.) The sample test blocks were ultrasonically cleaned in alkaline solutions and AUGER analysis was used by Honeywell FM and T to validate their cleanliness. This information enabled selection of final cleaning techniques and solutions to be used for the bonding trials. To validate Honeywell's AUGER data and to verify the cleaning processes in actual situations, additional sample blocks were cleaned (using the chosen processes) and then bonded. The bond quality of the test blocks was analyzed according to Pratt and Whitney's requirements. The Charpy impact testing was performed according to ASTM procedure {number_sign}E-23. Bond quality was determined by examining metallographic samples of the bonded test blocks for porosity along the bondline.
Date: February 2, 2000
Creator: Hand, T.E. & Bohnert, G.W.
Partner: UNT Libraries Government Documents Department

U.S. Department of Energy National Center of Excellence for Metals Recycle

Description: The US Department of Energy (DOE) National Center of Excellence for Metals Recycle has recently been established. The vision of this new program is to develop a DOE culture that promotes pollution prevention by considering the recycle and reuse of metal as the first and primary disposition option and burial as a last option. The Center of Excellence takes the approach that unrestricted release of metal is the first priority because it is the most cost-effective disposition pathway. Where this is not appropriate, restricted release, beneficial reuse, and stockpile of ingots are considered. Current recycling activities include the sale of 40,000 tons of scrap metal from the East Tennessee Technology Park (formerly K-25 Plant) K-770 scrap yard, K-1064 surplus equipment and machinery, 7,000 PCB-contaminated drums, 12,000 tons of metal from the Y-l2 scrap yard, and 1,000 metal pallets. In addition, the Center of Excellence is developing a toolbox for project teams that will contain a number of specific tools to facilitate metals recycle. This Internet-based toolbox will include primers, computer programs, and case studies designed to help sites to perform life cycle analysis, perform ALARA (As Low As is Reasonably Achievable) analysis for radiation exposures, provide pollution prevention information and documentation, and produce independent government estimates. The use of these tools is described for two current activities: disposition of scrap metal in the Y-12 scrapyard, and disposition of PCB-contaminated drums.
Date: May 1, 1998
Creator: Adams, V.; Bennett, M. & Bishop, L.
Partner: UNT Libraries Government Documents Department

Additional Interface Corner Toughness Data for an Adhesively-Bonded Butt Joint

Description: Over a period of 15 months, five sets of adhesively-bonded butt joints were fabricated and tested. This previously unreported data is used to assess the variability of measured interface corner toughness values, K{sub ac}, as well as the dependence of K{sub ac} on surface preparation. A correlation between K{sub ac} and the size of the adhesive failure zone is also noted.
Date: April 14, 1999
Creator: Guess, T.R. & Reedy, E.D.
Partner: UNT Libraries Government Documents Department

Cu interactions with {alpha}-Al{sub 2}O{sub 3}(0001): Effects of surface hydroxyl groups vs. dehydroxylation by Ar ion sputtering

Description: XPS studies and first principles calculations compare Cu adsorption on heavily hydroxylated sapphire (0001) with a dehydroxylated surface produced by Ar{sup +} sputtering followed by annealing in O{sub 2}. Annealing a cleaned sapphire sample with an O{sub 2} partial pressure of {approximately}5 x 10{sup {minus}6} Torr removes most contaminants, but leaves a surface with {approximately}0.4ML carbon and {approximately}0.4ML OH. Subsequent light (6 min.) Ar ion sputtering at 1 KeV reduces the carbon to undetectable levels but does not dehydroxylate the surface. Further sputtering at higher Ar ion excitation energies (>2 KeV) partially dehydroxylates the surface, while 5 KeV Ar ion sputtering creates oxygen vacancies in the surface region. Further annealing in O{sub 2} repairs the oxygen vacancies in the top layers but those beneath the surface remain. Deposition of Cu on the hydroxylated surface at 300 K results in a maximum Cu(I) coverage of {approximately}0.35 ML, in agreement with theoretical predictions.
Date: February 8, 2000
Creator: NIU,C.; SHEPHERD,K.; MARTINI,D.; KELBER,J.A.; JENNISON,DWIGHT R. & BOGICEVIC,ALEXANDER
Partner: UNT Libraries Government Documents Department

Electrodissolution studies of 304 stainless steel in sodium nitrate electrolyte

Description: To explore the impact of a wide range of operating parameters upon 304 stainless steel (SS) dissolution in sodium nitrate (NaNO{sub 3}) electrolyte, the staff of Engineering Science Applications-Energy and Process Engineering performed a series of beaker experiments. The variables that the authors explored included NaNO{sub 3} concentration, chromate concentration, pH, stirring rate, and current density. They adjusted the run length to obtain approximately 10 mg/cm{sup 2} metal removal so that they could compare surface finishes under similar test conditions. Key findings may be summarized as follows. Current efficiency during dissolution depends most strongly upon current density and electrolyte concentration. At 0.05 A/cm{sup 2}, current density is more dependent upon chromium concentration than they previously thought. They obtained the best surface finish in a classical electropolishing regime at current densities above 1.5 A/cm{sup 2}. Mirror-like finishes were obtained at near 100% current efficiency. At 0.05 a/cm{sup 2} they obtained reasonable surface finishes, particularly at lower electrolyte concentration. Current efficiency was low (30%). At intermediate current densities, they obtained the worst surface finishes, that is, surfaces with severe pitting. Also, they explored preferential attack of the weld zone during electrodissolution of 304 stainless steel cans. Electrodissolution removed approximately twice as much material from cans with unshielded weld zones as from cans with shielded weld zones. The following implications are apparent. While operation above 1 A/cm{sup 2} yields the best surface finish at 100% current efficiency, equipment size and power feedthrough limitations reduce the attractiveness of this option. Because other Los Alamos researchers, obtained more favorable results with the sulfate electrolyte, the authors recommend no further work for the sodium nitrate electrolyte system.
Date: December 1, 1997
Creator: Weisbrod, K.R.; Trujillo, V.L. & Martinez, H.E.
Partner: UNT Libraries Government Documents Department

Electrochemical decontamination system for actinide processing gloveboxes

Description: An electrolytic decontamination technology has been developed and successfully demonstrated at Los Alamos National Laboratory (LANL) for the decontamination of actinide processing gloveboxes. The technique decontaminates the interior surfaces of stainless steel gloveboxes utilizing a process similar to electropolishing. The decontamination device is compact and transportable allowing it to be placed entirely within the glovebox line. In this way, decontamination does not require the operator to wear any additional personal protective equipment and there is no need for additional air handling or containment systems. Decontamination prior to glovebox decommissioning reduces the potential for worker exposure and environmental releases during the decommissioning, transport, and size reduction procedures which follow. The goal of this effort is to reduce contamination levels of alpha emitting nuclides for a resultant reduction in waste level category from High Level Transuranic (TRU) to low Specific Activity (LSA, less than or equal 100 nCi/g). This reduction in category results in a 95% reduction in disposal and disposition costs for the decontaminated gloveboxes. The resulting contamination levels following decontamination by this method are generally five orders of magnitude below the LSA specification. Additionally, the sodium sulfate based electrolyte utilized in the process is fully recyclable which results in the minimum of secondary waste. The process bas been implemented on seven gloveboxes within LANL`s Plutonium Facility at Technical Area 55. Of these gloveboxes, two have been discarded as low level waste items and the remaining five have been reused.
Date: March 1, 1998
Creator: Wedman, D.E.; Lugo, J.L.; Ford, D.K.; Nelson, T.O.; Trujillo, V.L. & Martinez, H.E.
Partner: UNT Libraries Government Documents Department

Decontamination technologies evaluations

Description: Testing has been completed at the Idaho Chemical Processing Plant (ICPP) on in situ recyclable abrasives grit blasting, concrete cleaning (using scabbling, chemicals and electro-kinetics) and laser light ablation of metals. Several small scale tests have also been conducted with strippable coatings, CO{sub 2} pellet blasting and various other techniques. The results of this testing is summarized in this paper.
Date: May 1, 1996
Creator: Tripp, J.
Partner: UNT Libraries Government Documents Department

NSTX Filament Preionization and Glow Discharge Cleaning Systems

Description: Initial NSTX GDC experiments were performed with one moveable anode and a biased filament preionization system that allowed D2 and He Glow Discharge breakdowns at the actual operating pressure, voltage and current. The biased filament system was also operated continuously during ohmic operations, and used to reduce volt-sec consumption for February 1999 plasma discharges up to 280 KA. An upgraded system has been installed with 2 fixed wall anodes and 3 biased filaments; 2 on the mid-plane and one in the divertor region; all separately controllable remotely using a PLC system. Recent applications include assisting in preionization for 800 KA plasma discharges.
Date: November 1, 1999
Creator: H.W. Kugel, W. Blanchard, G. D'Amico, R. Gernhardt, T. Provost
Partner: UNT Libraries Government Documents Department