@article{maheshwari_stevie_myneni_ciovati_rigsbee_dhakal_griffis_2014, title={SIMS analysis of high-performance accelerator niobium}, volume={46}, ISSN={["1096-9918"]}, DOI={10.1002/sia.5461}, abstractNote={Niobium is used to fabricate superconducting radio frequency accelerator modules because of its high critical temperature, high critical magnetic field, and easy formability. Recent experiments have shown a very significant improvement in performance (over 100%) after a high‐temperature bake at 1400 °C for 3 h. SIMS analysis of this material showed the oxygen profile was significantly deeper than the native oxide with a shape that is indicative of diffusion. Positive secondary ion mass spectra showed the presence of Ti with a depth profile similar to that of O. It is suspected that Ti is associated with the performance improvement. The source of Ti contamination in the anneal furnace has been identified, and a new furnace was constructed without Ti. Initial results from the new furnace do not show the yield improvement. Further analyses should determine the relationship of Ti to cavity performance. Copyright © 2014 John Wiley & Sons, Ltd.}, journal={SURFACE AND INTERFACE ANALYSIS}, author={Maheshwari, P. and Stevie, F. A. and Myneni, G. R. and Ciovati, G. and Rigsbee, J. M. and Dhakal, P. and Griffis, D. P.}, year={2014}, month={Nov}, pages={288–290} }
 @article{stevie_maheshwari_pierce_adekore_griffis_2013, title={SIMS analysis of zinc oxide LED structures: quantification and analysis issues}, volume={45}, ISSN={["1096-9918"]}, DOI={10.1002/sia.4919}, abstractNote={Zinc oxide (ZnO) is a wide band gap semiconductor that shows great promise for development of light emitting diode structures. Interest in this technology has increased significantly, but even though controlled n‐type doping can be readily achieved, p‐type doping has been difficult. Numerous potential p‐type dopants were investigated in this SIMS study using a CAMECA IMS‐6F. The dopants and other elements of interest were quantified by use of ion implantation into ZnO substrates. Relative sensitivity factor values were obtained for H, Li, N, F, Na, Mg, Al, Si, K, Ga, As, Se, Ag, Cd, Te. Sample charging was encountered for some specimens, and adjacent electron neutralization procedures were employed. ZnO structures were prepared and subsequently analyzed with both O2+ and Cs+ primary beams. Depth profiles exposed a number of analysis issues. Because of the large number of elements, especially those at low atomic number, that were present in the structures, many mass interferences were encountered. Ag in particular was very difficult to monitor. Matrix effects were also noted, especially when high Mg doping was used. The need to monitor Al, Na, and K in the near surface region required analysis without conductive Au coating to reduce contamination. With careful choice of secondary ion species, it was possible to monitor the elements of primary interest using O2+ primary beam. SIMS demonstrated the ability to characterize the layers in the ZnO structure, including quantum wells, and to determine dopant and contaminant levels. Copyright © 2012 John Wiley & Sons, Ltd.}, number={1}, journal={SURFACE AND INTERFACE ANALYSIS}, author={Stevie, F. A. and Maheshwari, P. and Pierce, J. M. and Adekore, B. T. and Griffis, D. P.}, year={2013}, month={Jan}, pages={352–355} }
 @article{penley_stevie_griffis_2012, title={Quantification of cesium surface contamination on silicon resulting from SIMS analysis}, volume={30}, ISSN={["2166-2746"]}, DOI={10.1116/1.3698400}, abstractNote={In order to improve the understanding of unintended cesium (Cs) contamination that occurs during SIMS depth profiling, Cs concentrations on sample surfaces were measured before analysis and at various distances from a depth profile crater after analysis. Cs concentrations in excess of 1 at. % were found directly adjacent to the depth profile analysis site. Cs was also detected at significant concentrations hundreds of micrometers from the depth profile measurement location. This Cs contamination can originate from a number of sources including Cs beam tails, Cs neutral beam, and secondary sputtering from instrument optics and other structures. Since the presence of cesium significantly affects the secondary ion yield of electronegative elements (e.g., phosphorus) in silicon, the unintended presence of cesium on the surface of a previously analyzed sample can strongly affect the reproducibility and accuracy of low dose electronegative element measurements, especially at the surface.}, number={3}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B}, author={Penley, C. and Stevie, F. A. and Griffis, D. P.}, year={2012} }
 @article{zhou_li_garcia_crawford_beck_hinks_griffis_2012, title={Time-of-Flight-Secondary Ion Mass Spectrometry Method Development for High-Sensitivity Analysis of Acid Dyes in Nylon Fibers}, volume={84}, ISSN={["1520-6882"]}, DOI={10.1021/ac3025569}, abstractNote={A minimally destructive technique for the determination of dyes in finished fibers provides an important tool for crime scene and other forensic investigations. The analytical power and the minimal sample consumption of time-of-flight-secondary ion mass spectrometric (TOF-SIMS) analysis provides the ability to obtain definitive molecular and elemental information relevant to fiber identification, including identification of dyes, from a very small volume of sample. For both fiber surface analysis and, with the aid of cryomicrotomy, fiber cross-section analysis, TOF-SIMS was used to identify various dyes in finished textile fibers. The analysis of C.I. Acid Blue 25 in nylon is presented as a representative example. The molecular ion of C.I. Acid Blue 25 with lower than 3% on weight-of-fiber (owf) dye loading cannot be identified on dyed nylon surfaces by TOF-SIMS using a Bi(3)(+) primary ion beam. Sputtering with C(60)(+) provided the ability to remove surface contamination as well as at least partially remove Bi-induced damage, resulting in a greatly improved signal-to-noise ratio for the Acid Blue 25 molecular ion. The use of C(60)(+) for damage removal in a cyclic manner along with Bi for data acquisition provided the ability to unambiguously identify Acid Blue 25 via its molecular ion at a concentration of 0.1% owf from both fiber surfaces and cross sections.}, number={22}, journal={ANALYTICAL CHEMISTRY}, author={Zhou, Chuanzhen and Li, Min and Garcia, Roberto and Crawford, Anne and Beck, Keith and Hinks, David and Griffis, Dieter P.}, year={2012}, month={Nov}, pages={10085–10090} }
 @article{maheshwari_stevie_myeneni_ciovati_rigsbee_griffis_2011, title={Analysis of Interstitial Elements in Niobium with Secondary Ion Mass Spectrometry (SIMS)}, volume={1352}, ISBN={["978-0-7354-0909-5"]}, ISSN={["0094-243X"]}, DOI={10.1063/1.3579233}, abstractNote={Superconducting Radio Frequency (SRF) cavities provide enhanced efficiency and reduced energy utilization in present day particle accelerators. Niobium (Nb) is the material of choice for these cavities due to its high critical temperature and critical magnetic field. In order to understand why certain treatments, especially a low temperature bake, improve performance, it is important to study Nb surface characteristics and identify elemental contamination that can affect the performance of the cavity. H, C, O, and N are of interest because they are interstitial impurities in Nb. In earlier work, SIMS analysis using a CAMECA IMS‐6F with Cs+ primary beam showed that C and N were probably not significant factors impacting performance but there was a very high level of H in the Nb. Ion implants of C, N, O, and D into Nb provided quantification of C, N, O and indicated that D is very mobile in the Nb. Further analyses showed that heat treated Nb has lower levels of surface H than non heat treated Nb and subseq...}, journal={INTERNATIONAL SYMPOSIUM ON THE SUPERCONDUCTING SCIENCE & TECHNOLOGY OF INGOT NIOBIUM}, author={Maheshwari, P. and Stevie, F. A. and Myeneni, G. and Ciovati, G. and Rigsbee, J. M. and Griffis, D. P.}, year={2011}, pages={151-+} }
 @article{zhou_li_chiang_lucia_griffis_2011, title={Chemical and Spatial Differentiation of Syringyl and Guaiacyl Lignins in Poplar Wood via Time-of-Flight Secondary Ion Mass Spectrometry}, volume={83}, ISSN={["1520-6882"]}, DOI={10.1021/ac200903y}, abstractNote={As a major component in plant cell walls, lignin is an important factor in numerous industrial processes, especially in wood saccharification and fermentation to biofuels. The ability to chemically differentiate and spatially locate lignins in wood cell structures provides an important contribution to the effort to improve these processes. The spatial distribution of the syringyl (S) and guaiacyl (G) lignins, both over larger regions and within a single cell wall, on poplar ( Populus trichocarpa ) wood cross-sections was determined via time-of-flight secondary ion mass spectrometry (ToF-SIMS). This is the first time that direct chemically specific mass spectrometric mapping has been employed to elucidate the spatial distribution of S and G lignins. In agreement with results obtained by UV microscopy, ToF-SIMS images clearly show that the guaiacyl lignin is predominantly located in the vessel cell walls of poplar wood while syringyl lignin is mainly located in the fiber cell walls. The G/S ratio in vessel cell walls was determined to be approximately twice that found in fiber cell walls. A combination of Bi ToF-SIMS spectral image acquisition and C(60) sputtering provided the ability to attain the combination of spatial resolution and signal-to-noise necessary to determine the distribution of S and G lignins in a single cell wall. By this technique, it was possible to demonstrate that more guaiacyl lignin is located in the middle lamella layer and more syringyl lignin is located in the inner cell wall area.}, number={18}, journal={ANALYTICAL CHEMISTRY}, author={Zhou, Chuanzhen and Li, Quanzi and Chiang, Vincent L. and Lucia, Lucian A. and Griffis, Dieter P.}, year={2011}, month={Sep}, pages={7020–7026} }
 @article{maheshwari_tian_reece_kelley_myneni_stevie_rigsbee_batchelor_griffis_2011, title={Surface analysis of Nb materials for SRF cavities}, volume={43}, ISSN={["1096-9918"]}, DOI={10.1002/sia.3513}, abstractNote={Abstract}, number={1-2}, journal={SURFACE AND INTERFACE ANALYSIS}, author={Maheshwari, P. and Tian, H. and Reece, C. E. and Kelley, M. J. and Myneni, G. R. and Stevie, F. A. and Rigsbee, J. M. and Batchelor, A. D. and Griffis, D. P.}, year={2011}, pages={151–153} }
 @article{wong_haslauer_anantharamaiah_pourdeyhimi_batchelor_griffis_2010, title={Focused Ion Beam Characterization of Bicomponent Polymer Fibers}, volume={16}, ISSN={["1431-9276"]}, DOI={10.1017/s1431927610000115}, abstractNote={Abstract}, number={3}, journal={MICROSCOPY AND MICROANALYSIS}, author={Wong, K. C. and Haslauer, C. M. and Anantharamaiah, N. and Pourdeyhimi, B. and Batchelor, A. D. and Griffis, D. P.}, year={2010}, month={Jun}, pages={282–290} }
 @article{ciovati_myneni_stevie_maheshwari_griffis_2010, title={High field Q slope and the baking effect: Review of recent experimental results and new data on Nb heat treatments}, volume={13}, ISSN={["1098-4402"]}, DOI={10.1103/physrevstab.13.022002}, abstractNote={Here, the performance of superconducting radio-frequency (SRF) cavities made of bulk Nb at high fields (peak surface magnetic field greater than about 90 mT) is characterized by exponentially increasing rf losses (high-field Q-slope), in the absence of field emission, which are often mitigated by low temperature (100-140 °C, 12-48 h) baking. In this contribution, recent experimental results and phenomenological models to explain this effect will be briefly reviewed. New experimental results on the high-field Q-slope will be presented for cavities that had been heat treated in a vacuum furnace at high temperature without subsequent chemical etching. These studies are aimed at understanding the role of hydrogen on the high-field Q-slope and at the passivation of the Nb surface during heat treatment. Improvement of the cavity performances, particularly of the cavities’ quality factor, have been obtained following the high temperature heat-treatments, while SIMS surface analysis measurements on Nb samples treated with the cavities revealed significantly lower hydrogen concentration than for samples that followed standard cavity treatments.}, number={2}, journal={PHYSICAL REVIEW SPECIAL TOPICS-ACCELERATORS AND BEAMS}, author={Ciovati, G. and Myneni, G. and Stevie, F. and Maheshwari, P. and Griffis, D.}, year={2010}, month={Feb} }
 @article{penley_stevie_griffis_siebel_kulig_lee_2010, title={Secondary ion mass spectrometry characterization of anomalous behavior for low dose ion implanted phosphorus in silicon}, volume={28}, ISSN={["2166-2746"]}, DOI={10.1116/1.3406141}, abstractNote={Significant changes over time have been observed in surface and near surface phosphorus concentration for low dose phosphorus implants measured using secondary ion mass spectrometry (SIMS) with cesium bombardment. These variations in concentration affect the ability to make reproducible dose measurements. Phosphorus measurements have been documented for samples from wafers kept at ambient conditions and also for those stored in a range of other conditions including heat, high humidity, low humidity, and liquid nitrogen. An initial study of wafers ion implanted over a range of doses showed that the change in the surface phosphorus concentration was most apparent for the lowest phosphorus dose (1×1012 atoms/cm2) and that heating the sample resulted in the most significant change (increase in almost three orders of magnitude) in apparent surface P concentration. Only the specimens stored at liquid nitrogen temperature showed no change in P surface concentration. SIMS analysis conditions were optimized and a second set of analyses were performed on wafers that included different wafer processing (thicker surface oxide, preamorphization, and anneal) in an effort to reduce the change in surface phosphorus. Significant improvement in P dose reproducibility was noted for the wafer that had been implanted through a 5 nm oxide and stored in dry conditions.}, number={3}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B}, author={Penley, C. and Stevie, F. A. and Griffis, D. P. and Siebel, S. and Kulig, L. and Lee, J.}, year={2010}, month={May}, pages={511–516} }
 @article{zhu_stevie_griffis_2008, title={Model study of electron beam charge compensation for positive secondary ion mass spectrometry using a positive primary ion beam}, volume={254}, DOI={10.1016/j.apsusc.2007.10.008}, abstractNote={A new modeling approach has been developed to assist in the SIMS analysis of insulating samples. This approach provides information on the charging phenomena occurring when electron and positive primary ion beams impact a low conductivity material held at a high positive potential. The concept of effective leakage resistance aids in the understanding of the dynamic electrical properties of an insulating sample under dynamic analysis conditions. Modeling of steady state electron beam charge compensation involves investigation of electron injection and charge drift. Using a Monte Carlo program to simulate electron injection and dc conduction calculations to predict charge drift, detailed information regarding charging phenomena can be determined.}, number={9}, journal={Applied Surface Science}, author={Zhu, Z. M. and Stevie, F. A. and Griffis, D. P.}, year={2008}, pages={2708–2711} }
 @article{stevie_griffis_2008, title={Quantification in dynamic SIMS: Current status and future needs}, volume={255}, ISSN={["0169-4332"]}, DOI={10.1016/j.apsusc.2008.05.041}, abstractNote={Dynamic SIMS has made great strides in quantification. The use of ion-implanted standards has made quantification routine for any element in a wide range of matrices. Both contaminant and matrix measurements can be reliably quantified in the same depth profile for selected multi-element substrates, such as SiGe and AlGaN. Dose measurements with less than 1% reproducibility have been demonstrated for magnetic sector, quadrupole, and time-of-flight instruments. Progress has been made in quantification at the surface, at interfaces, in thin layers, in insulators, within small areas, and for two and three dimensions. Current challenges include quantification in a proliferation of layers, interfaces, and elements, and obtaining quantitative information from the smallest possible area. Analyses using complementary techniques will be useful for these difficult SIMS measurements. Focused ion beam specimen preparation has shown promise for small area and three-dimensional analyses. Developments in ion sources show potential for small area analysis using focused ion beam SIMS.}, number={4}, journal={APPLIED SURFACE SCIENCE}, author={Stevie, F. A. and Griffis, D. P.}, year={2008}, month={Dec}, pages={1364–1367} }
 @article{zhu_gu_stevie_griffis_2007, title={Improved understanding of an electron beam charge compensation method for magnetic sector secondary ion mass spectrometer analysis of insulators}, volume={25}, ISSN={["0734-2101"]}, DOI={10.1116/1.2746044}, abstractNote={Good charge compensation has historically been difficult to achieve for secondary ion mass spectrometry positive secondary ion depth profile analysis of highly insulating samples using a magnetic sector secondary ion mass spectrometer. A new charge compensation method has been developed utilizing an adjacent electron beam approach. A combination of computational simulation and quantitative characterization of the charge compensation phenomenon was used to elucidate the underlying mechanisms of this charge compensation technique with the goal of further improving this method. Results of this approach show that a low intensity electron shower consisting of secondary and backscattered electrons resulting from the impact of the primary electron beam with elements in the electron beam flight path may be responsible for charge compensation. It is also determined that the charge compensation provided by the adjacent impact technique can be further improved to provide better profile stability, higher mass resolut...}, number={4}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A}, author={Zhu, Z. and Gu, C. and Stevie, F. A. and Griffis, D. P.}, year={2007}, pages={769–774} }
 @article{harton_zhu_stevie_griffis_ade_2007, title={Mass fractionation of carbon and hydrogen secondary ions upon Cs+ and O-2(+) bombardment of organic materials}, volume={25}, ISSN={["1520-8559"]}, DOI={10.1116/1.2718957}, abstractNote={A phenomenon known as mass fractionation has been probed in organic materials using secondary ion mass spectrometry (SIMS). Mass fractionation occurs because two isotopes of a particular species (i.e., identical number of protons, but different number of neutrons) do not have identical secondary ion yields in a constant chemical environment. Two primary ion probes, Cs+ and O2+, have been utilized with detection of negative and positive secondary ions, respectively, using a magnetic sector mass spectrometer. These two analysis conditions have been found to yield considerably different mass fractionation effects as a result of different sputtering and ionization mechanisms. Also, as determined previously with SIMS analysis of inorganic materials, the lower molecular weight species carbon and hydrogen are particularly susceptible to mass fractionation effects. Because organic materials are primarily composed of carbon and hydrogen, and because isotopic labeling is often utilized to accurately analyze such materials, knowledge of these effects in organic materials is essential for quantitative SIMS analysis.}, number={3}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A}, author={Harton, Shane E. and Zhu, Zhengmao and Stevie, Frederick A. and Griffis, Dieter P. and Ade, Harald}, year={2007}, pages={480–484} }
 @article{a.d. garetto_a.d. batchelor_griffis_p.e._russell_2007, title={Transferable Internal Reservoir Device for Electron and Ion Beam Induced Chemistry}, volume={86}, journal={Microscopy and Analysis}, author={A.D. Garetto, R.R. Garcia and A.D. Batchelor, C.L. Progl and Griffis, D.P. and P.E. and Russell}, year={2007}, pages={5–6} }
 @article{gu_stevie_bennett_garcia_griffis_2006, title={Back side SIMS analysis of hafnium silicate}, volume={252}, ISSN={["1873-5584"]}, DOI={10.1016/j.apsusc.2006.02.099}, abstractNote={Abstract High-k dielectrics are under study as part of the effort to continually reduce semiconductor device dimensions and hafnium silicate (HfSixOy) is one of the most promising high-k materials. A requirement of the dielectric is that the constituent elements cannot diffuse into adjacent device regions during thermal processing. Analysis for inter-diffusion using front side SIMS of high-k dielectrics has been complicated by matrix and sputtering effects. Use of a back side analysis sample preparation procedure that was successful for copper diffusion and site specific studies produced a HfSiO specimen that has less than 250 nm silicon remaining and minimal slope over the analysis region. Magnetic Sector (CAMECA IMS-6F) SIMS analysis of this specimen with low energy O2+ bombardment does not show the matrix and sputtering effects noted in the front side data. Sufficient depth resolution was obtained to define the interface between the silicon substrate and the HfSiO layer and indicate what appears to be an interfacial layer. There is no indication of hafnium diffusion into the silicon substrate.}, number={19}, journal={APPLIED SURFACE SCIENCE}, publisher={Elsevier BV}, author={Gu, C. and Stevie, F. A. and Bennett, J. and Garcia, R. and GriffiS, D. P.}, year={2006}, month={Jul}, pages={7179–7181} }
 @article{harton_stevie_griffis_ade_2006, title={SIMS depth profiling of deuterium labeled polymers in polymer multilayers}, volume={252}, ISSN={["0169-4332"]}, DOI={10.1016/j.apsusc.2006.02.146}, abstractNote={Abstract Thin planar polymer films are model systems for probing physical phenomena related to molecular confinement at polymer surfaces and polymer/polymer interfaces. Existing experimental techniques such as forward recoil spectrometry (FRES) and neutron reflectometry (NR) have been used extensively for analysis of these systems, although they suffer from relatively low depth resolution (FRES) or difficulties associated with inversion to real space (NR). In contrast, secondary ion mass spectrometry (SIMS) can provide real-space depth profiles of tracer labeled polymers directly with sufficient depth resolution for optimal analyses of these systems. Deuterated polystyrene (dPS) has been employed as the tracer polymer and has been embedded in a matrix of either unlabeled polystyrene (PS) or poly(cyclohexyl methacrylate) (PCHMA). These doped films have been placed on either poly(methyl methacrylate) (PMMA) or poly(2-vinyl pyridine) (P2VP) and thermally annealed. Varied analysis conditions for a magnetic sector SIMS instrument (CAMECA IMS-6f) were used to optimize the depth resolution and detection sensitivity while minimizing matrix effects and sample charging. Both Cs+ and O2+ primary ions have been used along with detection of negative and positive secondary ions, respectively. Impact energy and primary ion species have been shown to affect matrix secondary ion count rate for the various films studied.}, number={19}, journal={APPLIED SURFACE SCIENCE}, author={Harton, Shane E. and Stevie, Fred A. and Griffis, Dieter P. and Ade, Harald}, year={2006}, month={Jul}, pages={7224–7227} }
 @article{gu_stevie_hitzman_saripalli_johnson_griffis_2006, title={SIMS quantification of matrix and impurity species in AlxGa1-xN}, volume={252}, ISSN={["1873-5584"]}, DOI={10.1016/j.apsusc.2006.02.148}, abstractNote={The quantification in Al x Ga 1-x N with different AlN mole fraction (x) is challenging because of matrix effects and charging effects. For quantitative characterization of both matrix and impurity elements in Al x Ga 1-x N, a novel charge neutralization method was employed and calibration curves were created using an O 2 + primary beam with positive secondary ion detection and a Cs + primary beam with negative and MCs + secondary ion detection. Over the range of 0 < x < 0.58, the matrix ion intensity ratios of Al + /Ga + and AlCs + /GaCs + appear linear with the mole fraction ratio x/(1-x), and the ratio of AlN - /GaN - is linear with AlN mole fraction (x). The sputter rate decreases as AlN mole fraction increases, while the relative sensitivity factors (RSF's) of impurities have an exponential relationship with AlN mole fraction. These calibration curves allow the quantification of both matrix and impurity species in AlGaN with varying AlN mole fraction. The technique can be employed for impurity control, composition and growth rate determination, as well as structural analysis of the finished optoelectronic and electronic devices.}, number={19}, journal={APPLIED SURFACE SCIENCE}, author={Gu, C. J. and Stevie, F. A. and Hitzman, C. J. and Saripalli, Y. N. and Johnson, M. and Griffis, D. P.}, year={2006}, month={Jul}, pages={7228–7231} }
 @article{sivasubramani_lee_kim_kim_gnade_wallace_edge_schlom_stevie_garcia_et al._2006, title={Thermal stability of lanthanum scandate dielectrics on Si(100)}, volume={89}, ISSN={["0003-6951"]}, DOI={10.1063/1.2405418}, abstractNote={The authors have examined the thermal stability of amorphous, molecular beam deposited lanthanum scandate dielectric thin films on top of Si (100) after a 1000°C, 10s rapid thermal anneal. After the anneal, crystallization of LaScO3 is observed. Excellent suppression of lanthanum and scandium diffusion into the substrate silicon is indicated by the back-side secondary ion mass spectrometry (SIMS) analyses. In contrast, front-side SIMS and high-resolution electron energy loss analyses of the amorphous Si∕LaScO3∕Si (100) stack indicated the outdiffusion of lanthanum and scandium into the silicon capping layer during the anneal.}, number={24}, journal={APPLIED PHYSICS LETTERS}, author={Sivasubramani, P. and Lee, T. H. and Kim, M. J. and Kim, J. and Gnade, B. E. and Wallace, R. M. and Edge, L. F. and Schlom, D. G. and Stevie, F. A. and Garcia, R. and et al.}, year={2006}, month={Dec} }
 @article{mosselveld_makarov_lundquist_griffis_russell_2004, title={Circuit editing of copper and low-k dielectrics in nanotechnology devices}, volume={214}, ISSN={["1365-2818"]}, DOI={10.1111/j.0022-2720.2004.01337.x}, abstractNote={Summary}, journal={JOURNAL OF MICROSCOPY}, author={Mosselveld, F and Makarov, VV and Lundquist, TR and Griffis, DP and Russell, PE}, year={2004}, month={Jun}, pages={246–251} }
 @article{pivovarov_stevie_griffis_2004, title={Improved charge neutralization method for depth profiling of bulk insulators using O-2(+) primary beam on a magnetic sector SIMS instrument}, volume={231}, ISSN={["1873-5584"]}, DOI={10.1016/j.apsusc.2004.03.070}, abstractNote={Use of electrons for charge neutralization during positive secondary ion SIMS analysis of insulators has typically been achieved using coincident primary ion and electron beams. The normal incidence electron gun on CAMECA magnetic sector SIMS instruments can effectively eliminate sample charging during analysis of thin insulating films if the electron energy is sufficient to penetrate the film. However, positive secondary ion SIMS bulk insulator analysis using this instrument can be difficult, especially if high sputtering rates are required. A neutralization method has been developed utilizing electron beam impact of a region adjacent to the sputtered area. Prior to analysis, the surface of the sample is coated with gold which provides a conductive surface layer and which has a high secondary and backscattered electron yield. Results have been obtained showing excellent neutralization for a variety of bulk insulators including glass, silica, alumina, and lithium niobate. Sputtering rates exceeding 2 nm/s have been achieved in bulk silica. The technique should be applicable to minerals and possibly for other materials in cases where the analyzed area cannot be directly irradiated with an electron beam.}, journal={APPLIED SURFACE SCIENCE}, author={Pivovarov, AL and Stevie, FA and Griffis, DP}, year={2004}, month={Jun}, pages={786–790} }
 @article{kachan_hunter_kouzminov_pivovarov_gu_stevie_griffis_2004, title={O-2(+) versus Cs+ for high depth resolution depth profiling of III-V nitride-based semiconductor devices}, volume={231}, ISSN={["1873-5584"]}, DOI={10.1016/j.apsusc.2004.03.211}, abstractNote={Abstract Optimum depth resolution with adequate sensitivity for the elements of interest is required to obtain the information desired from SIMS analysis of multilayer nitride III–V structures. For many of the species of interest, particularly the p-type dopants, O2+ bombardment at low energy is often used. Use of Cs+ bombardment and detection of the cesium attachment secondary ions (CsM+ where M is the element of interest) may provide several advantages over O2+ analysis. Using similar low primary ion impact energy analysis conditions for O2+ and Cs+ on CAMECA IMS-6f and IMS-4f instruments, the depth resolution obtained for positive secondary ions is compared.}, journal={APPLIED SURFACE SCIENCE}, author={Kachan, M and Hunter, J and Kouzminov, D and Pivovarov, A and Gu, J and Stevie, F and Griffis, D}, year={2004}, month={Jun}, pages={684–687} }
 @article{gu_pivovarov_garcia_stevie_griffis_moran_kulig_richards_2004, title={Secondary ion mass spectrometry backside analysis of barrier layers for copper diffusion}, volume={22}, ISSN={["1071-1023"]}, DOI={10.1116/1.1617278}, abstractNote={Secondary ion mass spectrometry (SIMS) backside analyses have been performed on a Cu/TaN/Ta/SiO2/Si structure to determine barrier effectiveness for Cu diffusion. Sample backside access to the barrier layers was obtained by removal of the Si substrate using a polishing method that maintains parallelism between the sample surface and the polished back side by monitoring changes in facets at the four corners of the specimen. Determination of the Si thickness remaining during the polishing process was improved through the use of optical interference measurements using a narrow band pass optical filter. Samples having slopes with respect to the original surface less than 6 nm over 60 μm have been obtained. A difference in polishing rate between SiO2 and Si was exploited to obtain this parallelism. For SIMS analyses, the presence of a SiO2 layer required electron gun charge neutralization for the O2+ 0.5 keV impact energy analysis. SIMS analyses show the ability to distinguish all layers and to monitor copper through the barrier material. With the high depth resolution conditions used, SIMS analyses were able to provide detailed elemental distribution information such as the presence of nitrogen at specific interfaces.}, number={1}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B}, author={Gu, C and Pivovarov, A and Garcia, R and Stevie, F and Griffis, D and Moran, J and Kulig, L and Richards, JF}, year={2004}, pages={350–354} }
 @article{gu_garcia_pivovarov_stevie_griffis_2004, title={Site-specific SIMS backside analysis}, volume={231}, ISSN={["1873-5584"]}, DOI={10.1016/j.apsusc.2004.03.140}, abstractNote={For maximum SIMS depth resolution for any layer in a sample, the depth profile should begin only as far from the layer as necessary to establish a constant implant concentration of the primary ion beam species. Depth resolution and detection limit can be severely degraded if it is necessary to sputter through an over layer having non uniform sputtering properties or containing a high level of the impurity of interest prior to reaching the layer of interest. A SIMS backside analysis method based on mechanical polishing is extended to allow site-specific SIMS backside depth profile analysis. Optical microscopy employing a red filter was used to allow direct viewing of the site to be depth profiled both during polishing and in situ during SIMS analysis. Depth profile analyses were performed on 100μm×100 μm device test structures. Sample charging resulting from insulator layers present in these device test structures was alleviated using a modified sample mounting technique. Backside SIMS depth profile analysis using an O2+ primary ion beam having an impact energy of 1.25 keV was used to determine if boron had penetrated a thin SiO2 layer.}, journal={APPLIED SURFACE SCIENCE}, publisher={Elsevier BV}, author={Gu, C and Garcia, R and Pivovarov, A and Stevie, F and Griffis, D}, year={2004}, month={Jun}, pages={663–667} }
 @article{pivovarov_gu_stevie_griffis_2004, title={Utilization of electron impact ionization of gaseous and sputtered species in the secondary ion acceleration region of a magnetic sector SIMS instrument}, volume={231}, ISSN={["1873-5584"]}, DOI={10.1016/j.apsusc.2004.03.069}, abstractNote={Negative secondary ion insulator analysis using a normal incidence electron gun (NEG) on CAMECA magnetic sector SIMS instruments can be difficult due to an inability to adequately determine the electron beam impact region during NEG alignment. The electron impact energy is too low to utilize phosphor cathodoluminescent materials that can be used for NEG alignment for positive secondary ion analyses. Detection of electron beam desorbed H− is often used for NEG alignment, but the presence of H on the surface is not always uniform and it is transient, making it difficult to determine whether variations in the H− secondary ion intensity are due to non-uniformity of the electron beam or of the H on the sample. To overcome this difficulty, a new technique has been developed that takes advantage of sputtering of the sample surface by positive ions created by electron impact ionization in the spectrometer secondary ion acceleration region between the sample and the immersion lens of the mass spectrometer. The formation of the ions occurs by interaction of residual gas species in the spectrometer secondary ion acceleration region with the NEG electron beam. This method is used to align the NEG for negative secondary ion charge neutralization.}, journal={APPLIED SURFACE SCIENCE}, author={Pivovarov, A and Gu, C and Stevie, F and Griffis, D}, year={2004}, month={Jun}, pages={781–785} }
 @misc{russell_griffis_gonzales perez_2003, title={Chemically enhanced focused ion beam micro-machining of copper}, volume={6,645,872}, number={2003 Nov. 11}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Russell, P. E. and Griffis, D. P. and Gonzales Perez, J. C.}, year={2003} }
 @article{wang_griffis_garcia_russell_2003, title={Etching characteristics of chromium thin films by an electron beam induced surface reaction}, volume={18}, ISSN={["0268-1242"]}, DOI={10.1088/0268-1242/18/4/302}, abstractNote={In this paper, we demonstrate the etching of chromium (Cr) film on quartz through a surface reaction induced by an electron beam and enhanced with XeF2 gas. We have studied the influences of the electron beam energy, the gas flow rate and the specimen composition on the etch rate. The electron beam energy has significant influence on the etch rate. The etch rate made by an electron beam of 20 keV is five times higher compared to that made by a beam of 10 keV. The XeF2 gas flow rate shows little effect on the etch rate when the gas pressure is higher than 2 × 10−6 Torr. The structure and grain size of the Cr film did not show any apparent change under exposure to XeF2 or when irradiated by an electron beam, while the composition of Cr has a significant effect on the etch process. The material removal of Cr induced by an electron beam means that it can be applied to the direct fabrication of microstructures on Cr films and that it solves the contamination problem in Cr mask repair.}, number={4}, journal={SEMICONDUCTOR SCIENCE AND TECHNOLOGY}, author={Wang, JH and Griffis, DP and Garcia, R and Russell, PE}, year={2003}, month={Apr}, pages={199–205} }
 @article{pivovarov_stevie_griffis_guryanov_2003, title={Optimization of secondary ion mass spectrometry detection limit for N in SiC}, volume={21}, ISSN={["0734-2101"]}, DOI={10.1116/1.1595108}, abstractNote={Controlled changes in the Cs+ primary ion beam density and analytical expressions describing the sources (bulk concentration, memory effect, and adsorption of N from the residual vacuum) of secondary ion mass spectrometry analyte secondary ion intensities were used to determine the contributions to the N secondary ion intensity obtained during the analysis of trace levels of N in bulk SiC. This methodology allows the determination of N concentrations that can be substantially less than the apparent N secondary ion background intensity. It was shown that for the Cameca IMS-6F instrumental conditions used, memory effect is the main contributor to the N background signal. Taking into consideration the Cs+ beam diameter, the raster size, the diameter of the ion-extracted area, and the impurity secondary ion intensity, an optimized combination of primary ion beam current and raster size was determined that resulted in the best detection limit for N in bulk SiC. This detection limit for N in bulk SiC (∼6×1014 atoms/cm3) was obtained for a primary ion current of 100 nA, a raster size of 45 μm×45 μm, and a secondary ion extraction area diameter of 30 μm.}, number={5}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A}, author={Pivovarov, AL and Stevie, FA and Griffis, DP and Guryanov, GM}, year={2003}, pages={1649–1654} }
 @article{loesing_guryanov_phillips_griffis_2002, title={Comparison of secondary ion mass spectroscopy analysis of ultrashallow phosphorus using Cs+, O-2(+), and CsC6- primary ion beams}, volume={20}, ISSN={["2166-2746"]}, DOI={10.1116/1.1450588}, abstractNote={It is well known that reducing the work function of the sample surface using Cs+ ions increases the negative ion yield of phosphorus. It is also well known that a shallow primary beam implantation depth (RP) is required for achieving high depth resolution during the analysis of ultrashallow implant profiles. The combination of the opposite polarities of the positive Cs+ primary ion beam and the negatively biased sample (the combination most often used for P analysis using magnetic sector secondary ion mass spectroscopy) unfortunately accelerates the Cs+ ions towards the sample thus limiting the degree to which the primary ion impact energy can be reduced [R. Loesing, G. M. Guryanov, J. L. Hunter, and D. P. Griffis, J. Vac. Sci. Technol. B 18, 509 (2000)]. A low primary ion beam impact energy and high impact angle, both of which result in lower RP, can be obtained using a negatively charged cluster ion such as CsC6− (Peabody negative ion source) impacting on a negatively biased sample [G. Gillen, L. King, B. Freibaum, R. Lareau, and J. Bennett, in Secondary Ion Mass Spectrometry, SIMS XII, edited by A. Benninghoven et al. (Elsevier, Amsterdam, 2000), p. 279; R. Loesing, G. M. Guryanov, and D. P. Griffis, in Proceedings of the 13th Annual SIMS Workshop, Lake Tahoe, 2000, p. 36]. If, however, Cs is not required to improve secondary ion yield, a low energy O2+ primary beam impacting on a positively biased sample can be used [I. M. Abdelrehim, T. H. Büyüklimanli, S. P. Smith, and C. W. Magee, in Secondary Ion Mass Spectrometry SIMS XII, edited by A. Benninghoven (Elsevier, Amsterdam, 2000), p. 279; S. P. Smith, C. J. Hitzman, and C. W. Magee, in Secondary Ion Mass Spectrometry, SIMS XI, edited by G. Gillen (Wiley, Chichester, 1998), p. 277]. In this case, the reduction in sensitivity for P due to the loss of the negative ion yield enhancing Cs can be partly compensated by flooding the sample surface with oxygen. In this study Cs+, CsC6−, and O2+ primary ions are compared for depth profiling of ultrashallow phosphorus in Si in terms of decay length, sensitivity, and crater bottom roughness.}, number={2}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B}, author={Loesing, R and Guryanov, GM and Phillips, MS and Griffis, DP}, year={2002}, pages={507–511} }
 @article{gonzalez_silva_griffis_russell_2002, title={Improvements in focused ion beam micromachining of interconnect materials}, volume={20}, ISSN={["2166-2746"]}, DOI={10.1116/1.1515310}, abstractNote={Focused ion beam micromachining (FIBM) of integrated circuits continues to be an important tool for design debug, editing, and verification; for metrology; and for process control. FIBM of copper interconnects has presented challenges not faced when micromachining aluminum interconnects and the introduction of low-k dielectrics present additional challenges. A new approach to chemically assisted FIBM of thin film Cu, SiO2, and SiLK low-k material using polar precursor molecules has been investigated. Polar alcohols were used to reduce the sputter rate of SiO2 and SiLK while having a minimal effect on the Cu sputter rate. A new FIBM process based on the reduction of the FIB Ga+ energy from the typical 25 to 15 keV is also introduced. The new low energy FIBM process was shown to increase the sputter rate of polycrystalline Cu with strong (111) crystallographic texture by a factor of 2.5. This increase in the sputter rate of Cu combined with a slight reduction of the sputter rate of SiO2 and SiLK results in a Cu/SiO2 selectivity of greater than 7 and a Cu/SiLK selectivity of approximately 3. These are the largest selectivity values reported until now for both systems. The Onderdelinden theory of single-crystal sputtering was used to explain this seemingly anomalous increase of the Cu sputter rate with the reduction of the FIB Ga+ energy.}, number={6}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B}, author={Gonzalez, JC and Silva, MIN and Griffis, DP and Russell, PE}, year={2002}, pages={2700–2704} }
 @article{gonzalez_griffis_miau_russell_2001, title={Chemically enhanced focused ion beam micromachining of copper}, volume={19}, ISSN={["2166-2746"]}, DOI={10.1116/1.1418406}, abstractNote={Chemically enhanced focused ion beam micromachining of thin film Cu on Si substrates has been investigated. Barrier layers and dielectric layers were considered as well. The gases investigated include the Cl containing examples of C2Cl4, C2H4Cl2, and CHCl2CCl3 as well as the oxygen containing gases ethanol, and methanol and water vapor. Crystallographic channeling effect results in nonuniform Cu milling, insufficient selectivity and poor end-point detection. However, the gases investigated were shown to enhance the milling homogeneity, improve the end-point detection, and provide higher selectivity. A Cu/SiO2 selectivity of greater than 4 was obtained when using ethanol as the etching gas.}, number={6}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B}, author={Gonzalez, JC and Griffis, DP and Miau, TT and Russell, PE}, year={2001}, pages={2539–2542} }
 @article{phillips_griffis_russell_2000, title={Channeling effects during focused-ion-beam micromachining of copper}, volume={18}, ISSN={["0734-2101"]}, DOI={10.1116/1.582300}, abstractNote={The rapid introduction of copper metallization for semiconductor devices has prompted increased research into focused-ion-beam micromachining of copper. Studies with the aim of increasing the material removal rate of Cu by focused-ion-beam micromachining have been complicated by variable micromachining behavior apparently resulting from differing Cu film morphologies produced by the various Cu deposition procedures. This work examined the micromachining behavior of thin copper films produced by physical-vapor deposition (PVD) and electroplating, as well as single-crystal copper samples. PVD copper films were found to be preferentially textured along 〈111〉, with a columnar grain structure. Channeling effects within this type of grain structure provide a geometric enhancement of the material removal rate of 30% when the sample normal is tilted 12° from the incident ion beam, regardless of sample rotation. Single-crystal (111) copper was found to exhibit similar material removal rate enhancement (averaged over 360° rotation) when tilted 12°, verifying that the etching enhancement observed in the PVD films is directly related to their 〈111〉 texture. Compared to the PVD film, electroplated (EP) copper thin films contained a significantly more random grain orientation. Consequently, the EP films did not exhibit any appreciable variation in material removal rate beyond the expected cosine dependence when tilted with respect to the incident Ga+ beam normal. Micromachining of the electroplated films, which have larger randomly oriented grains, results in grain decoration due to preferential etching producing severe micromachining-induced topography.}, number={4}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS}, author={Phillips, JR and Griffis, DP and Russell, PE}, year={2000}, pages={1061–1065} }
 @misc{russell_griffis_shedd_stark_vitarelli_2000, title={Method for water vapor enhanced charged-particle-beam machining}, volume={6,140,655}, number={2000 Oct. 31}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Russell, P. E. and Griffis, D. P. and Shedd, G. M. and Stark, T. J. and Vitarelli, J.}, year={2000} }
 @inbook{hunter_bates_patel_loesing_guraynov_griffis_2000, title={Optimization of SIMS analysis conditions for ultra-shallow phosphorus and arsenic implants}, volume={165}, ISBN={0750306858}, number={2000}, booktitle={Microbeam Analysis 2000: proceedings of the Second Conference of the International Union of Microbeam Analysis Societies held in Kailua-Kona, Hawaii, 9-14 July 2000}, publisher={Bristol: Institute of Physics Publishing}, author={Hunter, J. L. and Bates, T. B. and Patel, S. B. and Loesing, R. and Guraynov, G. and Griffis, D. P.}, editor={Williams, D. B. and Shimizu, R.Editors}, year={2000}, pages={327–328} }
 @article{loesing_guryanov_hunter_griffis_2000, title={Secondary ion mass spectrometry depth profiling of ultrashallow phosphorous in silicon}, volume={18}, ISSN={["1071-1023"]}, DOI={10.1116/1.591222}, abstractNote={High-precision quantitative secondary ion mass spectrometry (SIMS) trace analyses of ultrashallow P31 distributions in Si (i.e., junction depths of 50 nm or less) require the ability to eliminate the Si130H mass interference while simultaneously minimizing primary ion impact energy and maximizing sensitivity. Elimination of Si130H requires a relatively high mass resolution SIMS instrument such as the Cameca IMS-6f used in this work. A range of Cs+ primary ion energies ranging from 9.5 to 1.6 keV was investigated to determine which provided the best depth resolution as measured by decay length for ultrashallow depth profiles of 2 keV P in Si. Improvements (or lack thereof) in decay length as the primary ion impact energy was reduced were correlated with crater bottom roughness measurements. Changes in the ion yields of P and Si resulting from both the appreciable fraction of the analyzed depth made up of the surface native oxide and also from the depth required for the primary ion yield enhancing Cs+ to reach a constant level were also investigated utilizing bulk-doped P in Si. The resulting ion yield transients obtained were then used to generate an empirical correction function with the aim of improving the quantitative accuracy of the ultrashallow depth profile selected as having the minimum decay length obtained in this work. Finally, improvements in the P detection limit provided by optimization of the secondary ion postacceleration system are discussed.}, number={1}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B}, author={Loesing, R and Guryanov, GM and Hunter, JL and Griffis, DP}, year={2000}, pages={509–513} }
 @misc{russell_griffis_shedd_stark_vitarelli_1999, title={Method for water vapor enhanced charged-particle-beam machining}, volume={5,958,799}, number={1999 Sept. 28}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Russell, P. E. and Griffis, D. P. and Shedd, G. M. and Stark, T. J. and Vitarelli, J.}, year={1999} }
 @article{bremser_perry_nam_griffis_loesing_ricks_davis_1998, title={Acceptor and donor doping of AlxGa1-xN thin film alloys grown on 6H-SiC(0001) substrates via metalorganic vapor phase epitaxy}, volume={27}, ISSN={["0361-5235"]}, DOI={10.1007/s11664-998-0392-9}, number={4}, journal={JOURNAL OF ELECTRONIC MATERIALS}, author={Bremser, MD and Perry, WG and Nam, OH and Griffis, DP and Loesing, R and Ricks, DA and Davis, RF}, year={1998}, month={Apr}, pages={229–232} }
 @article{russell_stark_griffis_phillips_jarausch_1998, title={Chemically and geometrically enhanced focused ion beam micromachining}, volume={16}, ISSN={["1071-1023"]}, DOI={10.1116/1.590197}, abstractNote={Improvements in focused ion beam (FIB) material removal rates utilizing geometric and chemical enhancement were investigated. Geometrical optimization of FIB micromachining of Permalloy and diamond was investigated to determine the magnitude of material removal rate gains that could be attained by increasing the angle of the ion beam with respect to the sample surface normal. The combination of geometrical optimization with chemical enhancement (C2Cl4 for Permalloy and H2O and XeF2 for diamond) was then investigated to determine whether additional gains in material removal rate could be attained. FIB sharpening of a diamond nanoindenter tip is also presented as a practical example of diamond micromachining with H2O as the removal rate enhancing species.}, number={4}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B}, author={Russell, PE and Stark, TJ and Griffis, DP and Phillips, JR and Jarausch, KF}, year={1998}, pages={2494–2498} }