@misc{lucovsky_niimi_2004, title={Remote plasma-assisted oxidation of SiC: a low temperature process for SiC-SiO2 interface formation that eliminates interfacial Si oxycarbide transition regions}, volume={16}, ISSN={["1361-648X"]}, DOI={10.1088/0953-8984/16/17/018}, abstractNote={Remote plasma-assisted oxidation of SiC is a low temperature process, 300 °C, for the formation of device quality interfaces on SiC. This paper discusses two aspects of the process: (i) the motivation for eliminating high temperature oxidation processes that can generate silicon oxycarbide, Si–O–C, interfacial regions which can be a source of interfacial defects and (ii) the kinetics of the remote plasma-assisted oxidation process that effectively eliminates interfacial Si oxycarbide transition regions. The differences between interfacial relaxation at Si–SiO2 and SiC–SiO2 are based on the relative stabilities of the suboxides of Si and SiC, SiOx and (Si,C)Ox, respectively.}, number={17}, journal={JOURNAL OF PHYSICS-CONDENSED MATTER}, author={Lucovsky, G and Niimi, H}, year={2004}, month={May}, pages={S1815–S1837} }
 @article{khandelwal_niimi_lucovsky_lamb_2002, title={Low-temperature Ar/N-2 remote plasma nitridation of SiO2 thin films}, volume={20}, ISSN={["0734-2101"]}, DOI={10.1116/1.1513635}, abstractNote={Low-temperature nitridation of SiO2 thin films by Ar/N2 remote plasma processing was investigated using on-line Auger electron spectroscopy, angle-resolved x-ray photoelectron spectroscopy (ARXPS), and optical emission spectroscopy (OES). Nitridation experiments were performed at 300 °C using 30 W Ar/N2 remote plasmas at 0.1 and 0.3 Torr. Ar/N2 remote plasma exposure of 5 nm SiO2 films for 30 min results in nitrogen incorporation throughout the films, independent of process pressure and plasma reactor configuration (i.e., upstream versus downstream N2 injection). ARXPS indicates a N–Si3 local bonding configuration with second nearest neighbor oxygen atoms. Ar/N2 remote plasma exposure at 0.1 Torr results in higher nitrogen concentrations (8–10 at. %). Reactor configuration has a negligible effect at 0.1 Torr; conversely, downstream N2 injection results in higher nitrogen concentrations (5–6 at. %) than upstream injection (3–4 at. %) at 0.3 Torr. OES indicates that the Ar/N2 remote plasmas contain N2 triplet excited states and ground-state N atoms. The Ar emission intensities and the saturation N concentrations in the resultant films follow similar trends with processing pressure and reactor configuration; the N2 first positive emission intensities run counter to these trends. We infer that low-temperature SiO2 nitridation by Ar/N2 remote plasmas is a two-step process: O removal by Ar+ ion bombardment and N insertion by plasma-generated active N species. Moreover, the first step appears to be rate limiting under the conditions employed in this study. Annealing the oxynitride films in N2 at 900 °C decreases the N concentration and results in a more uniform nitrogen distribution.}, number={6}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS}, author={Khandelwal, A and Niimi, H and Lucovsky, G and Lamb, HH}, year={2002}, pages={1989–1996} }
 @article{niimi_khandelwal_lamb_lucovsky_2002, title={Reaction pathways in remote plasma nitridation of ultrathin SiO2 films}, volume={91}, ISSN={["1089-7550"]}, DOI={10.1063/1.1419208}, abstractNote={Low-temperature nitridation of 3 nm SiO2 films using He/N2 and N2 remote radio frequency (rf) plasmas was investigated. On-line Auger electron spectroscopy and angle-resolved x-ray photoelectron spectroscopy (ARXPS) were employed to determine the concentration, spatial distribution, and local chemical bonding of nitrogen in the resultant films. Experiments were performed using a substrate temperature of 300 °C and 30 W rf power. Nitridation using an upstream He/N2 remote plasma at 0.1 Torr incorporates nitrogen at the top surface of the SiO2 film. In contrast, a lower concentration of nitrogen distributed throughout the film is obtained when the process pressure is increased to 0.3 Torr. ARXPS indicates a N–Si3 local bonding configuration, irrespective of the spatial distribution of N atoms. Slightly more nitrogen is incorporated using a downstream He/N2 plasma at each process pressure. By comparison, nitridation of SiO2 films using a N2 remote plasma at 0.1 Torr is very slow. Optical emission spectroscopy indicates that He dilution enhances the generation of N2+(B 2Σu+) species by altering the plasma electron energy distribution and by providing an additional kinetic pathway (Penning ionization). Changing the He/N2 remote plasma configuration from upstream to downstream (at 0.1 and 0.3 Torr) also enhances N2+(B 2Σu+) generation. For upstream He/N2 remote plasmas, the intensity of N2 first positive emission from N2(B 3Πg) states increases with pressure, whereas the N2+ first negative emission from N2+(B 2Σu+) states decreases. We infer from these observations that N2+ species are primarily responsible for top surface nitridation at 0.1 Torr, and that neutral species [N2(A 3Σu+) metastables and N atoms] are associated with sub-surface nitrogen incorporation.}, number={1}, journal={JOURNAL OF APPLIED PHYSICS}, author={Niimi, H and Khandelwal, A and Lamb, HH and Lucovsky, G}, year={2002}, month={Jan}, pages={48–55} }
 @article{niimi_yang_lucovsky_keister_rowe_2000, title={Barrier layer model determined by XPS data for tunneling current reductions at monolayer nitrided Si-SiO(2) interfaces}, volume={166}, ISSN={["0169-4332"]}, DOI={10.1016/S0169-4332(00)00480-3}, abstractNote={This paper builds on previous work that has demonstrated that interfacial suboxide transition regions at Si–SiO2 interfaces modify tunneling oscillations in the Fowler–Nordheim regime. This paper extends this approach to the direct tunneling regime, emphasizing differences in interfacial transition regions between Si–SiO2 interfaces with and without monolayer level interface nitridation. Tunneling currents in devices with the same oxide-equivalent thickness are reduced by monolayer level interfacial nitrogen with respect to devices without interface nitridation for both substrate and gate injection in both the direct and Fowler–Nordheim tunneling regimes. These decreases have been combined with physically thicker stacked oxide/nitride dielectrics to yield significantly reduced tunneling compared to devices with oxides of the same equivalent oxide thickness, tox-eq; e.g., tunneling currents ∼5×10−3 A/cm2 at 1 V for tox-eq∼1.6 nm have been obtained.}, number={1-4}, journal={APPLIED SURFACE SCIENCE}, author={Niimi, H and Yang, HY and Lucovsky, G and Keister, JW and Rowe, JE}, year={2000}, month={Oct}, pages={485–491} }
 @article{brillson_young_white_schafer_niimi_lee_lucovsky_2000, title={Depth-resolved detection and process dependence of traps at ultrathin plasma-oxidized and deposited SiO2/Si interfaces}, volume={18}, number={3}, journal={Journal of Vacuum Science & Technology. B, Microelectronics and Nanometer Structures}, author={Brillson, L. J. and Young, A. P. and White, B. D. and Schafer, J. and Niimi, H. and Lee, Y. M. and Lucovsky, G.}, year={2000}, pages={1737–1741} }
 @article{lucovsky_niimi_wu_yang_2000, title={Independent interface and bulk film contributions to reduction of tunneling currents in stacked oxide/nitride gate dielectrics with monolayer nitrided interfaces}, volume={159}, ISSN={["1873-5584"]}, DOI={10.1016/S0169-4332(00)00071-4}, abstractNote={Direct tunneling limits aggressive scaling of thermally-grown oxides to about ∼1.6 nm, a thickness at which the tunneling current at 1 V is ∼1 A/cm2. This paper presents experimental results, supported by interface characterizations and model calculations, which demonstrate that multi-layer or stacked gate dielectrics prepared by remote plasma processing comprised of (i) ultra-thin nitrided SiO2 interface layers, and (ii) either silicon nitride or oxynitride bulk dielectric films, can extend the oxide-equivalent thickness, tox-eq, limit down to ∼1.1–1.0 nm. A similar stacked gate dielectric, which substitutes higher-k oxides such as Zr(Hf)O2–SiO2 ‘silicate’ alloys or Ta2O5 for the nitrides or oxynitride alloys, is projected to further reduce tox-eq to ∼0.6–0.7 nm.}, journal={APPLIED SURFACE SCIENCE}, author={Lucovsky, G and Niimi, H and Wu, Y and Yang, H}, year={2000}, month={Jun}, pages={50–61} }
 @article{lucovsky_yang_niimi_keister_rowe_thorpe_phillips_2000, title={Intrinsic limitations on device performance and reliability from bond-constraint induced transition regions at interfaces of stacked dielectrics}, volume={18}, number={3}, journal={Journal of Vacuum Science & Technology. B, Microelectronics and Nanometer Structures}, author={Lucovsky, G. and Yang, H. and Niimi, H. and Keister, J. W. and Rowe, J. E. and Thorpe, M. F. and Phillips, J. C.}, year={2000}, pages={1742–1748} }
 @article{lucovsky_yang_niimi_thorpe_phillips_2000, title={Intrinsic limitations on ultimate device performance and reliability at (i) semiconductor-dielectric interfaces and (ii) internal interfaces in stacked dielectrics}, volume={18}, number={4}, journal={Journal of Vacuum Science & Technology. B, Microelectronics and Nanometer Structures}, author={Lucovsky, G. and Yang, H. and Niimi, H. and Thorpe, M. F. and Phillips, J. C.}, year={2000}, pages={2179–2186} }
 @article{johnson_niimi_lucovsky_2000, title={New approach for the fabrication of device-quality Ge/GeO2/SiO2 interfaces using low temperature remote plasma processing}, volume={18}, ISSN={["0734-2101"]}, DOI={10.1116/1.582331}, abstractNote={It has been shown that low temperature (300 °C) remote plasma enhanced processing can separately and independently control interface formation and bulk oxide deposition on silicon substrates. Plasma processing is followed by a low thermal budget thermal anneal, e.g., 30 s at 900 °C. In this article, this process has been modified and applied to germanium substrates to determine if it can provide a successful pathway to device-quality Ge–dielectric interfaces. The new process also employs a three-step process: (i) an O2/He plasma-assisted, predeposition oxidation of the germanium surface to form a superficial germanium–oxide passivating film, (ii) deposition of a SiO2 bulk film by remote plasma-enhanced chemical vapor deposition from SiH4 and O2, and (iii) a postdeposition anneal for chemical and structural relaxation. The resulting interfaces are improved by the predeposition, plasma-assisted oxidation step, but are still far too defective for device applications.}, number={4}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS}, author={Johnson, RS and Niimi, H and Lucovsky, G}, year={2000}, pages={1230–1233} }
 @article{lucovsky_yang_wu_niimi_2000, title={Plasma processed ultra-thin SiO2 interfaces far advanced silicon NMOS and PMOS devices: applications to Si-oxide Si oxynitride, Si-oxide Si nitride and Si-oxide transition metal oxide stacked gate dielectrics}, volume={374}, ISSN={["1879-2731"]}, DOI={10.1016/S0040-6090(00)01153-6}, abstractNote={Abstract The substitution of alternative gate dielectrics for thermally-grown SiO 2 and nitrided SiO 2 in aggressively scaled devices requires a significant processing change in going from thermally-grown to deposited dielectrics. This requires separate and independent steps for (i) the formation of Si-dielectric interface and (ii) the deposition of the dielectric thin film, which can be (a) Si nitride, or a Si oxynitride alloy, or (b) a high- k oxide. It is demonstrated that ultra-thin, nitrided Si–SiO 2 interface layers prepared by 300°C remote plasma processing can be effective in insulating device performance and reliability from deleterious effects associated direct deposition of alternative dielectric materials directly on to hydrogen-terminated Si surfaces. These interfaces perform equally well with Si nitride, Si oxynitride and high- k oxides, and contribute approximately 0.3–0.4 nm to the overall electrical oxide thickness (EOT), limiting aggressive scaling of EOT to approximately 0.6 nm.}, number={2}, journal={THIN SOLID FILMS}, author={Lucovsky, G and Yang, HY and Wu, Y and Niimi, H}, year={2000}, month={Oct}, pages={217–227} }
 @article{lucovsky_wu_niimi_yang_keister_rowe_2000, title={Separate and independent reductions in direct tunneling in oxide/nitride stacks with monolayer interface nitridation associated with the (i) interface nitridation and (ii) increased physical thickness}, volume={18}, ISSN={["0734-2101"]}, DOI={10.1116/1.582318}, abstractNote={Direct tunneling limits aggressive scaling of thermally grown oxides to about 1.6 nm, a thickness at which the tunneling current density Jg at 1 V is ∼1 A/cm2. This article demonstrates that stacked gate dielectrics prepared by remote plasma processing and including (i) ultrathin nitrided SiO2 interfacial layers and (ii) either silicon nitride or oxynitride bulk dielectrics can extend the equivalent oxide thickness to 1.1–1.0 nm before Jg exceeds 1 A/cm2. Significant reductions in direct tunneling are derived from (i) interface nitridation at the monolayer level and (ii) the increased physical thickness of the nitride or oxynitride alloy layers. The “portability” of the interface contribution is demonstrated by combining the nitrided SiO2 interface layers with transition-metal oxides, e.g., Ta2O5, in stacked gate dielectric structures and obtaining essentially the same reductions in tunneling current on n- and p-type substrates with respect to non-nitrided plasma-grown interface layers.}, number={4}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A}, author={Lucovsky, G and Wu, Y and Niimi, H and Yang, H and Keister, J and Rowe, JE}, year={2000}, pages={1163–1168} }
 @article{yang_niimi_keister_lucovsky_2000, title={The effects of interfacial sub-oxide transition regions and monolayer level nitridation on tunneling currents in silicon devices}, volume={21}, ISSN={["0741-3106"]}, DOI={10.1109/55.821673}, abstractNote={Direct tunneling (D-T) in Si metal-oxide-semiconductor (MOS) devices having 1.8 to 3 nm thick gate oxides is reduced approximately tenfold by monolayer Si-dielectric interface nitridation with respect to devices with nonnitrided interfaces. The reduction is independent of gate oxide-equivalent thickness, and gate or substrate injection, and extends into the Fowler-Nordheim tunneling (F-N-T) regime for thicker oxides as well. A barrier layer model, including sub-oxide transition regions, has been developed for the interface electronic structure for tunneling calculations using X-ray photoelectron spectroscopy data. These calculations provide a quantitative explanation for the observed tunneling current reductions.}, number={2}, journal={IEEE ELECTRON DEVICE LETTERS}, author={Yang, H and Niimi, H and Keister, JW and Lucovsky, G}, year={2000}, month={Feb}, pages={76–78} }
 @article{keister_rowe_kolodziej_niimi_madey_lucovsky_1999, title={Band offsets for ultrathin SiO2 and Si3N4 films on Si(111) and Si(100) from photoemission spectroscopy}, volume={17}, number={4}, journal={Journal of Vacuum Science & Technology. B, Microelectronics and Nanometer Structures}, author={Keister, J. W. and Rowe, J. E. and Kolodziej, J. J. and Niimi, H. and Madey, T. E. and Lucovsky, G.}, year={1999}, pages={1831–1835} }
 @article{lucovsky_wu_niimi_misra_phillips_1999, title={Bonding constraint-induced defect formation at Si-dielectric interfaces and internal interfaces in dual-layer gate dielectrics}, volume={17}, number={4}, journal={Journal of Vacuum Science & Technology. B, Microelectronics and Nanometer Structures}, author={Lucovsky, G. and Wu, Y. and Niimi, H. and Misra, V. and Phillips, J. C.}, year={1999}, pages={1806–1812} }
 @article{lucovsky_wu_niimi_misra_phillips_1999, title={Bonding constraints and defect formation at interfaces between crystalline silicon and advanced single layer and composite gate dielectrics}, volume={74}, ISSN={["1077-3118"]}, DOI={10.1063/1.123728}, abstractNote={An increasingly important issue in semiconductor device physics is understanding of how departures from ideal bonding at silicon–dielectric interfaces generate electrically active defects that limit performance and reliability. Building on previously established criteria for formation of low defect density glasses, constraint theory is extended to crystalline silicon–dielectric interfaces that go beyond Si–SiO2 through development of a model that quantifies average bonding coordination at these interfaces. This extension is validated by application to interfaces between Si and stacked silicon oxide/nitride dielectrics demonstrating that as in bulk glasses and thin films, an average coordination, Nav, greater than three yields increasing defective interfaces.}, number={14}, journal={APPLIED PHYSICS LETTERS}, author={Lucovsky, G and Wu, Y and Niimi, H and Misra, V and Phillips, JC}, year={1999}, month={Apr}, pages={2005–2007} }
 @article{young_bandhu_schafer_niimi_lucovsky_1999, title={Cathodoluminescence spectroscopy of nitrided SiO2-Si interfaces}, volume={17}, ISSN={["0734-2101"]}, DOI={10.1116/1.581806}, abstractNote={We use cathodoluminescence spectroscopy (CLS) to investigate the electronic states of ultrathin gate dielectrics with nitrided SiO2–Si interfaces, known to improve reliability in advanced complementary metal–oxide–semiconductor devices. The 5 nm thick films investigated were: (i) as-deposited (at 300 °C) structures, (ii) 400 °C hydrogen anneal, (iii) 900 °C rapid thermal anneal (RTA), and (iv) a combination of both anneals. CLS emission energies and intensities versus excitation energy were essentially unchanged for the as-deposited interface compared to non-nitrided plasma-processed interfaces. In the near-infrared, features appear at 0.8 and 1.0 eV, with the 1.0 eV peak Si substrate intensity increasing with increasing depth. From depth variation measurements at higher photon energy, a 3.4 eV peak is also shown to arise from the Si substrate, and a 2.7 eV feature is shown to come from the interface region. After hydrogenation, the CLS is essentially the same as for non-nitrided interfaces, except for an increase in the relative intensity of a broad background luminescence ranging from 1.5 to 2.5 eV. However, the RTA and the combination of the RTA and hydrogenation do not completely suppress emission near 2.0 eV feature as for non-nitrided interfaces. From the behavior of the CLS features, we are able to clearly distinguish between interfacial defects and substrate features, which are significantly reduced by the combined RTA/hydrogen anneal, and features that are not reduced by the annealing procedures.}, number={4}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS}, author={Young, AP and Bandhu, R and Schafer, J and Niimi, H and Lucovsky, G}, year={1999}, pages={1258–1262} }
 @article{therrien_niimi_gehrke_lucovsky_davis_1999, title={Charge redistribution at GaN-Ga2O3 interfaces: A microscopic mechanism for low defect density interfaces in remote plasma processed MOS devices prepared on polar GaN faces}, volume={48}, ISSN={["0167-9317"]}, DOI={10.1016/s0167-9317(99)00394-9}, abstractNote={Abstract Interfacial defect densities are typically two orders of magnitude higher at [III–V]-dielectric interfaces than at SiSiO 2 interfaces. This paper demonstrates GaN devices with significantly reduced interfacial defect densities using a two step remote plasma process to form the GaN-dielectric interface and then deposit the dielectric film. Separate plasma oxidation and deposition steps have previously been used for fabrication of aggressively scaled Si devices. Essentially the same 300°C remote plasma processing has been applied to GaN metal-oxide semiconductor (MOS) capacitors and field effect transistors (FETs). This paper i) discusses the low temperature plasma process for GaN device fabrication, ii) briefly reviews GaN device performance, and then iii) presents a chemical bonding model that provides a basis for the improved interface electrical properties.}, number={1-4}, journal={MICROELECTRONIC ENGINEERING}, author={Therrien, R and Niimi, H and Gehrke, T and Lucovsky, G and Davis, R}, year={1999}, month={Sep}, pages={303–306} }
 @article{misra_lazar_wang_wu_niimi_lucovsky_wortman_hauser_1999, title={Interfacial properties of ultrathin pure silicon nitride formed by remote plasma enhanced chemical vapor deposition}, volume={17}, number={4}, journal={Journal of Vacuum Science & Technology. B, Microelectronics and Nanometer Structures}, author={Misra, V. and Lazar, H. and Wang, Z. and Wu, Y. and Niimi, H. and Lucovsky, G. and Wortman, J. J. and Hauser, J. R.}, year={1999}, pages={1836–1839} }
 @article{niimi_lucovsky_1999, title={Monolayer-level controlled incorporation of nitrogen at Si-SiO(2) interfaces using remote plasma processing}, volume={17}, ISSN={["0734-2101"]}, DOI={10.1116/1.582041}, abstractNote={We demonstrate three different ways to incorporate nitrogen at Si–SiO2 interfaces: (i) an O2/He plasma oxidation of the Si surface followed by an N2/He plasma nitridation, (ii) an N2/He plasma nitridation of the Si surface, and (iii) a Si3N4 film deposition on to the Si surface. The two-step interface formation, the O2/He plasma oxidation followed by the N2/He plasma nitridation, is shown to yield significantly better interface device properties than the other two approaches. These differences in interface properties are explained by an application of constraint theory based on comparisons of the average bonding coordination of the dielectric layer at the interface with the Si substrate.}, number={6}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A}, author={Niimi, H and Lucovsky, G}, year={1999}, pages={3185–3196} }
 @article{niimi_lucovsky_1999, title={Monolayer-level controlled incorporation of nitrogen in ultrathin gate dielectrics using remote plasma processing: Formation of stacked 'N-O-N' gate dielectrics}, volume={17}, number={6}, journal={Journal of Vacuum Science & Technology. B, Microelectronics and Nanometer Structures}, author={Niimi, H. and Lucovsky, G.}, year={1999}, pages={2610–2621} }
 @article{keister_rowe_kolodziej_niimi_tao_madey_lucovsky_1999, title={Structure of ultrathin SiO2/Si(111) interfaces studied by photoelectron spectroscopy}, volume={17}, ISSN={["1520-8559"]}, DOI={10.1116/1.581805}, abstractNote={Device-grade ultrathin (9–22 Å) films of silicon dioxide, prepared from crystalline silicon by remote-plasma oxidation, are studied by soft x-ray photoelectron spectroscopy (SXPS). The 2p core-level spectra for silicon show evidence of five distinct states of Si, attributable to the five oxidation states of silicon between Si0 (the Si substrate) and Si4+ (the thin SiO2 film). The relative binding energy shifts for peaks Si1+ through Si4+ (with respect to Si0) are in agreement with earlier work. The relatively weaker signals found for the three intermediate states (I1, I2, and I3) are attributed to silicon atoms at the abrupt interface between the thin SiO2 film and substrate. Estimates of the interface state density from these interface signals agree with the values reported earlier of ∼2 monolayers (ML). The position and intensity of the five peaks are measured as a function of post-growth annealing temperature, crystal orientation, and exposure to He/N2 plasma. We find that annealing produces more abrupt interfaces (by reducing the suboxide interface state density), but never more abrupt than ∼1.5 monolayers. We observe a 15%–20% drop in the interface thickness (in particular the “Si2+” peak intensity) with increasing annealing temperature. Somewhat different behavior is observed with small amounts of nitrogen in the SiO2 film where an apparent increase in interface state density is seen. A quantitative analysis is presented which explores the effects of these sample preparation parameters in terms of relative interface state density and modeling of the SXPS data.}, number={4}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A}, author={Keister, JW and Rowe, JE and Kolodziej, JJ and Niimi, H and Tao, HS and Madey, TE and Lucovsky, G}, year={1999}, pages={1250–1257} }
 @article{wu_niimi_yang_lucovsky_fair_1999, title={Suppression of boron transport out of p(+) polycrystalline silicon at polycrystalline silicon dielectric interfaces}, volume={17}, number={4}, journal={Journal of Vacuum Science & Technology. B, Microelectronics and Nanometer Structures}, author={Wu, Y. and Niimi, H. and Yang, H. and Lucovsky, G. and Fair, R. B.}, year={1999}, pages={1813–1822} }
 @article{yang_niimi_wu_lucovsky_keister_rowe_1999, title={The effects of interfacial suboxide transition regions on direct tunneling in oxide and stacked oxide-nitride gate dielectrics}, volume={48}, ISSN={["0167-9317"]}, DOI={10.1016/s0167-9317(99)00395-0}, abstractNote={This paper builds on previous work that has demonstrated the effects of interfacial suboxide transition regions at SiSiO2 interfaces on tunneling oscillations in the Fowler-Nordheim regime. This paper extends thes effects to the direct tunneling regime and focuses on differences in interfacial transition regions between SiSiO2 interfaces with, and without monolayer level interface nitridation. Tunneling currents in devices with the same oxide-equivalent thickness are reduced by monolayer level interfacial nitrogen with respect to devices without interface nitridation for i) substrate and gate injection and ii) in both the direct and Fowler-Nordheim tunneling regimes.}, number={1-4}, journal={MICROELECTRONIC ENGINEERING}, author={Yang, H and Niimi, H and Wu, Y and Lucovsky, G and Keister, JW and Rowe, JE}, year={1999}, month={Sep}, pages={307–310} }
 @article{young_schafer_jessen_bandhu_brillson_lucovsky_niimi_1998, title={Cathodoluminescence measurements of suboxide band-tail and Si dangling bond states at ultrathin Si-SiO2 interfaces}, volume={16}, number={4}, journal={Journal of Vacuum Science & Technology. B, Microelectronics and Nanometer Structures}, author={Young, A. P. and Schafer, J. and Jessen, G. H. and Bandhu, R. and Brillson, L. J. and Lucovsky, G. and Niimi, H.}, year={1998}, pages={2177–2181} }
 @article{koh_niimi_lucovsky_green_1998, title={Controlled nitrogen incorporation at Si-SiO2 interfaces by remote plasma-assisted processing}, volume={37}, ISSN={["0021-4922"]}, DOI={10.1143/JJAP.37.709}, abstractNote={ 
    This paper presents experimental studies in which N-atoms have been incorporated at Si–SiO2   interfaces by forming the interface and oxide film by a 300°C remote plasma assisted   nitridation/oxidation process using N2O. Process dynamics have been studied by on-line Auger   electron spectroscopy (AES) by interrupted plasma processing. Based on AES studies using N2O,   O2 and sequenced N2O and O2 source gases, reaction pathways for i) N-atom incorporation at   and/or ii) removal from buried Si–SiO2 interfaces have been identified, and contrasted with reaction   pathways for nitridation using conventional furnace processing. 
    }, number={2}, journal={JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS}, author={Koh, K and Niimi, H and Lucovsky, G and Green, ML}, year={1998}, month={Feb}, pages={709–714} }
 @article{schafer_young_brillson_niimi_lucovsky_1998, title={Depth-dependent spectroscopic defect characterization of the interface between plasma-deposited SiO(2) and silicon}, volume={73}, ISSN={["0003-6951"]}, DOI={10.1063/1.122003}, abstractNote={We demonstrate the use of low-energy cathodoluminescence spectroscopy (CLS) to study optical transitions at defect bonding arrangements at Si–SiO2 interfaces prepared by low-temperature plasma deposition. Variable-depth excitation achieved by different electron injection energies provides a clear distinction between luminescence derived from (i) the near-interface region of the oxide film, (ii) the Si–SiO2 interface, and (iii) the underlying crystalline Si substrate. Cathodoluminescence bands at ∼0.8 and 1 eV are assigned to interfacial Si atom dangling bonds with different numbers of back-bonded Si and O atoms. CLS also reveals higher photon energy features: two bands at ∼1.9 and 2.7 eV assigned to suboxide bonding defects in the as-grown oxide films, as well as a substrate-related feature at ∼3.4 eV. The effects of hydrogenation at 400 °C and rapid thermal annealing at 900 °C, and especially the combination of both process steps is shown to dramatically reduce the intensities of the CLS features assigned to interfacial and suboxide bonding defects.}, number={6}, journal={APPLIED PHYSICS LETTERS}, author={Schafer, J and Young, AP and Brillson, LJ and Niimi, H and Lucovsky, G}, year={1998}, month={Aug}, pages={791–793} }
 @article{lucovsky_niimi_golz_kurz_1998, title={Differences between silicon oxycarbide regions at SiC-SiO(2) prepared by plasma-assisted oxidation and thermal oxidations}, volume={123}, ISSN={["0169-4332"]}, DOI={10.1016/S0169-4332(97)00469-8}, abstractNote={The initial stages of SiCSiO2 interface formation by low temperature (300°C) remote plasma assisted oxidation (RPAO) have been studied by on-line Auger electron spectroscopy (AES) for flat and vicinal 6H SiC(0001) wafers with Si(0001) and C faces (0001), focusing on (i) interfacial bonding and (ii) oxidation rates for thickness up to about 2 nm.}, journal={APPLIED SURFACE SCIENCE}, author={Lucovsky, G and Niimi, H and Golz, A and Kurz, H}, year={1998}, month={Jan}, pages={435–439} }
 @article{lucovsky_niimi_koh_green_1998, title={Monolayer nitrogen atom incorporation at buried Si-SiO2 interfaces: Preparation by remote plasma oxidation/nitridation and characterization by on-line auger electron spectroscopy}, volume={5}, ISSN={["0218-625X"]}, DOI={10.1142/S0218625X98000323}, abstractNote={ This paper presents experimental studies in which N-atoms have been incorporated at Si-SiO 2 interfaces by forming the interface and oxide film by a 300°C remote-plasma-assisted nitridation/oxidation process using N 2 O . Process dynamics have been studied by on-line Auger electron spectroscopy (AES) by interrupted plasma processing. Based on AES studies using N 2 O , O 2 and sequenced N 2 O and O 2 source gases, reaction pathways for (i) N-atom incorporation at and/or (ii) removal from buried Si-SiO 2 interfaces have been identified, and contrasted with reaction pathways for nitridation using conventional furnace processing. }, number={1}, journal={SURFACE REVIEW AND LETTERS}, author={Lucovsky, G and Niimi, H and Koh, K and Green, ML}, year={1998}, month={Feb}, pages={167–173} }
 @article{lucovsky_niimi_wu_parker_hauser_1998, title={Optimization of nitrided gate dielectrics by plasma-assisted and rapid thermal processing}, volume={16}, ISSN={["0734-2101"]}, DOI={10.1116/1.581291}, abstractNote={This article addresses several aspects of nitrogen atom (N atom) incorporation into ultrathin gate oxides including: (i) monolayer incorporation of N atoms at the Si–SiO2 interfaces to reduce tunneling currents and improve device reliability; and (ii) the incorporation of silicon nitride films into stacked oxide–nitride (ON) gate dielectrics to (a) increase the capacitance in ultrathin dielectrics without decreasing film thickness, and (b) suppress boron atom (B atom) diffusion from p+ polycrystalline Si gate electrodes through the dielectric layer to the Si substrate channel region. The results of this article demonstrate that these N-atom spatial distributions can be accomplished by low thermal budget, single wafer processing which includes (i) low-temperature (300 °C) plasma assisted oxidation, nitridation, and/or deposition to achieve the desired N-atom incorporation, followed by (ii) low thermal budget (30 s at 900 °C) rapid thermal annealing to promote chemical and structural bulk and interface relaxation.}, number={3}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A}, author={Lucovsky, G and Niimi, H and Wu, Y and Parker, CR and Hauser, JR}, year={1998}, pages={1721–1729} }
 @article{koh_niimi_lucovsky_1998, title={Plasma-engineered Si-SiO2 interfaces: monolayer nitrogen atom incorporation by low-temperature remote plasma-assisted oxidation in N2O}, volume={98}, ISSN={["0257-8972"]}, DOI={10.1016/S0257-8972(97)00392-7}, abstractNote={Abstract This paper presents experimental studies in which N-atoms have been incorporated at Si−SiO 2 interfaces by forming the interface and oxide film by a 300 °C remote plasma-assisted nitridation/oxidation process using N 2 O. Process dynamics have been studied by interrupted plasma processing using on-line Auger electron spectroscopy (AES). Based on the on-line AES, and complementary ex situ secondary ion mass spectroscopy and optical second harmonic generation results, monolayer nitrogen atom interface coverage has been confirmed. The factors that contribute to preferential nitrogen atom attachment at the Si−SiO 2 interface have been identified.}, number={1-3}, journal={SURFACE & COATINGS TECHNOLOGY}, author={Koh, K and Niimi, H and Lucovsky, G}, year={1998}, month={Jan}, pages={1524–1528} }
 @article{yang_niimi_lucovsky_1998, title={Tunneling currents through ultrathin oxide/nitride dual layer gate dielectrics for advanced microelectronic devices}, volume={83}, ISSN={["0021-8979"]}, DOI={10.1063/1.366976}, abstractNote={Direct and Fowler–Nordheim tunneling currents through oxide and dual layer silicon oxide–silicon nitride dielectrics are investigated for substrate and gate injection. The calculations include depletion effects in the heavily doped (n+) polysilicon gate electrodes as well as quantization effects in the less heavily doped n-type substrates. The Wentzel–Kramers–Brillouin (WKB) effective mass approximation has been compared with exact calculations for the tunneling probability, and based on these comparisons it has been found that the WKB approximation is adequate for single layer dielectrics, but is not for the dual layer dielectrics that are the focus of this article. Using exact tunneling transmission calculations, current-voltage (I–V) characteristics for ultrathin single layer oxides with different thicknesses (1.4, 2.0, and 2.3 nm) have been shown to agree well with recently reported experiments. Extensions of this approach demonstrate that direct tunneling currents in oxide/nitride structures with oxide equivalent thickness of 1.5 and 2.0 nm can be significantly lower than through single layer oxides of the same respective thickness.}, number={4}, journal={JOURNAL OF APPLIED PHYSICS}, author={Yang, HY and Niimi, H and Lucovsky, G}, year={1998}, month={Feb}, pages={2327–2337} }
 @article{niimi_lucovsky_1998, title={Ultrathin oxide gate dielectrics prepared by low temperature remote plasma-assisted oxidation}, volume={98}, ISSN={["0257-8972"]}, DOI={10.1016/S0257-8972(97)00389-7}, abstractNote={Monolayer N-atom incorporation at Si−SiO2 interfaces in device-quality SiO2 gate oxides has been accomplished by a three-step low-thermal budget process: (i) 300°C remote plasma-assisted oxidation in N2O to form the nitrided Si−SiO2 interface, (ii) 300°C remote plasma-assisted chemical vapor deposition from SiH4 and O2 or N2O to form the oxide layer, and (iii) a 30 s 900°C post-deposition rapid thermal anneal for chemical and structural relaxation. This paper reports on an extension of lowtemperature plasma processing to ultra-thin gate dielectrics (<3 nm) that is based on the first of the three steps identified above: the 300°C remote plasma-assisted oxidation in O2 or N2O. This paper: (i) highlights interrupted processing Auger electron spectroscopy measurements to monitor (a) growth rate and (b) interfacial nitrogen; (ii) discusses the reactions pathways for the plasma-assisted oxide growth process; (iii) contrasts (a) plasma-assisted and (b) furnace and rapid thermal oxidation processes.}, number={1-3}, journal={SURFACE & COATINGS TECHNOLOGY}, author={Niimi, H and Lucovsky, G}, year={1998}, month={Jan}, pages={1529–1533} }
 @article{lucovsky_banerjee_niimi_koh_hinds_meyer_lupke_kurz_1997, title={Elimination of sub-oxide transition regions at Si-SiO2 interfaces by rapid thermal annealing at 900 degrees C}, volume={117}, ISSN={["1873-5584"]}, DOI={10.1016/S0169-4332(97)80079-7}, abstractNote={In many spectroscopic studies, particularly by X-ray photoelectron spectroscopy, XPS, it has been generally assumed that the existence of sub-oxide transition regions at SiSiO2 interfaces were not strongly dependent on synthesis chemistries and processing conditions. This paper presents experimental evidence for a kinetically-limited phase transition at SiSiO2 interfaces at approximately 900°C that can minimize and to a large degree eliminate significant interfacial sub-oxide transition regions. The paper emphasizes a connection between (i) differences in photoluminescence from SiOx bulk films before and after 900°C annealing and (ii) differences in electrical performance of SiSiO2 interfaces and optical second harmonic generation from SiSiO2 interfaces, also before and after 900°C annealing}, journal={APPLIED SURFACE SCIENCE}, author={Lucovsky, G and Banerjee, A and Niimi, H and Koh, K and Hinds, B and Meyer, C and Lupke, G and Kurz, H}, year={1997}, month={Jun}, pages={202–206} }
 @article{golz_lucovsky_koh_wolfe_niimi_kurz_1997, title={Plasma-assisted formation of low defect density SiC-SiO2 interfaces}, volume={15}, number={4}, journal={Journal of Vacuum Science & Technology. B, Microelectronics and Nanometer Structures}, author={Golz, A. and Lucovsky, G. and Koh, K. and Wolfe, D. and Niimi, H. and Kurz, H.}, year={1997}, pages={1097–1104} }
 @article{niimi_koh_lucovsky_1997, title={Ultra-thin gate dielectrics prepared by low-temperature remote plasma-assisted oxidation}, volume={127}, ISSN={["0168-583X"]}, DOI={10.1016/S0168-583X(96)00958-5}, abstractNote={Abstract This paper discusses the formation of ultra-thin nitrided gate oxides by a low temperature plasma assisted oxidation process using remotely excited N2O as the source gas for both oxygen and nitrogen atoms. Three aspects of this process are addressed: (i) the differences in oxide growth rates for O2 or N2O plasma oxidation processes; (ii) the reaction pathways for the incorporation of nitrogen at the SiSiO2 interface for the N2O plasma process; and (iii) possible nitrogen atom depletion during processing steps that follow the plasma assisted oxidation/nitridation process.}, journal={NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS}, author={Niimi, H and Koh, K and Lucovsky, G}, year={1997}, month={May}, pages={364–368} }