S. Hussain, Abhishek Verma, K. Bera, Shahid Rauf, M. Goeckner
This study examines the transition of 13.56 MHz, capacitively coupled plasmas (CCP) from low to intermediate pressure regimes. Here, we investigate power deposition/plasma production in argon, nitrogen, and oxygen discharges as a function of pressure. These three feed gases were chosen as they provide a set of electropositive and electronegative gases and they are widely discussed in the existing literature. Experiments were conducted for all combinations of pressures: 0.5, 1.5, and 2.5 Torr, and nominal power density between 0.1 and 0.7 W/cm2 for each feed gas at a fixed electrode gap of 24 mm, a commonly employed gap in many industrial processes. Our study shows that increasing pressure results in an increase in current at a given electrode bias in argon and oxygen discharges, while there is no discernible pressure-induced change in nitrogen discharges. We attribute this increase to an increase in plasma density, which might result from a change in power deposition or ionization processes. It is likely that heating via secondary electrons becomes more important at intermediate pressures, resulting in increased plasma density and current. Specifically, based on our measurements, it appears that the mechanisms through which power is deposited into the plasma change with increasing pressure for both argon and oxygen discharges but not for nitrogen discharges. Our experimental results align with the outcomes of our simulations and the simulation results of CCP discharges conducted by other researchers under similar conditions.
{"title":"Power measurement analysis of moderate pressure capacitively coupled discharges","authors":"S. Hussain, Abhishek Verma, K. Bera, Shahid Rauf, M. Goeckner","doi":"10.1116/6.0003366","DOIUrl":"https://doi.org/10.1116/6.0003366","url":null,"abstract":"This study examines the transition of 13.56 MHz, capacitively coupled plasmas (CCP) from low to intermediate pressure regimes. Here, we investigate power deposition/plasma production in argon, nitrogen, and oxygen discharges as a function of pressure. These three feed gases were chosen as they provide a set of electropositive and electronegative gases and they are widely discussed in the existing literature. Experiments were conducted for all combinations of pressures: 0.5, 1.5, and 2.5 Torr, and nominal power density between 0.1 and 0.7 W/cm2 for each feed gas at a fixed electrode gap of 24 mm, a commonly employed gap in many industrial processes. Our study shows that increasing pressure results in an increase in current at a given electrode bias in argon and oxygen discharges, while there is no discernible pressure-induced change in nitrogen discharges. We attribute this increase to an increase in plasma density, which might result from a change in power deposition or ionization processes. It is likely that heating via secondary electrons becomes more important at intermediate pressures, resulting in increased plasma density and current. Specifically, based on our measurements, it appears that the mechanisms through which power is deposited into the plasma change with increasing pressure for both argon and oxygen discharges but not for nitrogen discharges. Our experimental results align with the outcomes of our simulations and the simulation results of CCP discharges conducted by other researchers under similar conditions.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":" 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140691702","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Cooper A. Voigt, Matthew Reingold, Alex Dube, Lawrence S. Early, Brent K. Wagner, Eric M. Vogel
The effects of substrate choice, substrate temperature, Se/In flux ratio, and cooling rate after deposition on the phase composition, surface morphology, and stoichiometry of indium selenide films synthesized via molecular beam epitaxy are presented. In2Se3 films were synthesized on sapphire, Si(111) and highly oriented, pyrolytic graphite (HOPG) substrates. The phase composition, stoichiometry, and surface morphology of the films were characterized via Raman spectroscopy, x-ray photoelectron spectroscopy, and atomic force microscopy, respectively. Higher substrate temperature combined with higher Se/In ratio promoted formation of β-In2Se3 over γ and/or κ-In2Se3 on all substrates. Higher Se/In ratio also independently promoted β-In2Se3 over γ and/or κ-In2Se3 on all substrates at 673 K. The lateral dimensions of In2Se3 flakes increased as the substrate temperature increased on all substrates, and the largest lateral dimensions were observed for β-In2Se3 flakes on HOPG at 973 K. No evidence of α-In2Se3 was observed in the Raman spectra of any of the films at any of the synthesis conditions in this study. β-In2Se3 films on HOPG were cooled at 1200, 120, and 12 K/h and no evidence of a β to α-In2Se3 phase transition was observed. Some evidence of β to α-In2Se3 phase transition was observed in temperature-dependent XRD of In2Se3 powders, suggesting that another parameter besides cooling rate is locking the In2Se3 films into the β-phase.
{"title":"Molecular beam epitaxy synthesis of In2Se3 films","authors":"Cooper A. Voigt, Matthew Reingold, Alex Dube, Lawrence S. Early, Brent K. Wagner, Eric M. Vogel","doi":"10.1116/6.0003508","DOIUrl":"https://doi.org/10.1116/6.0003508","url":null,"abstract":"The effects of substrate choice, substrate temperature, Se/In flux ratio, and cooling rate after deposition on the phase composition, surface morphology, and stoichiometry of indium selenide films synthesized via molecular beam epitaxy are presented. In2Se3 films were synthesized on sapphire, Si(111) and highly oriented, pyrolytic graphite (HOPG) substrates. The phase composition, stoichiometry, and surface morphology of the films were characterized via Raman spectroscopy, x-ray photoelectron spectroscopy, and atomic force microscopy, respectively. Higher substrate temperature combined with higher Se/In ratio promoted formation of β-In2Se3 over γ and/or κ-In2Se3 on all substrates. Higher Se/In ratio also independently promoted β-In2Se3 over γ and/or κ-In2Se3 on all substrates at 673 K. The lateral dimensions of In2Se3 flakes increased as the substrate temperature increased on all substrates, and the largest lateral dimensions were observed for β-In2Se3 flakes on HOPG at 973 K. No evidence of α-In2Se3 was observed in the Raman spectra of any of the films at any of the synthesis conditions in this study. β-In2Se3 films on HOPG were cooled at 1200, 120, and 12 K/h and no evidence of a β to α-In2Se3 phase transition was observed. Some evidence of β to α-In2Se3 phase transition was observed in temperature-dependent XRD of In2Se3 powders, suggesting that another parameter besides cooling rate is locking the In2Se3 films into the β-phase.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":" 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140691387","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Inho Seong, Ye-bin You, Youngseok Lee, M. Choi, Dain Sung, Geunyoung Yeom, Shinjae You
Reducing greenhouse gas emissions from semiconductor manufacturing has been attracting enormous interest in both industry and academia as global warming issues have increased in significance year by year. Among various strategies, the search for etch precursors that have low global warming potential is actively underway worldwide to reduce the use of conventional precursors with high global warming potential. In this paper, we explore the use of C6F6, a promising candidate to replace the widely utilized perfluorocarbon precursor C4F8, for plasma atomic layer etching (ALE) of SiO2. In situ ellipsometry results indicated that acceptable ALE characteristics were obtained with C4F8 and C6F6 each in their own specific ALE window, while C6F6 showed superior ALE performance. Investigation into the ALE performance with different precursors was then conducted based on plasma diagnostics for radical density, electron density, and plasma potential, and the results of which showed that the difference in the radical composition between precursors significantly affected the resulting ALE trends and also that the excellent ALE performance with C6F6 might originate from its significant polymeric characteristics. We expect the present findings to contribute to the wider adoption of low global warming potential precursors in the etching process.
随着全球变暖问题的重要性逐年增加，减少半导体制造过程中的温室气体排放引起了工业界和学术界的极大兴趣。在各种策略中，全世界都在积极寻找全球变暖潜能值低的蚀刻前驱体，以减少全球变暖潜能值高的传统前驱体的使用。在本文中，我们探讨了在二氧化硅的等离子体原子层蚀刻（ALE）中使用 C6F6 这一有望替代广泛使用的全氟化碳前驱体 C4F8 的候选物质。原位椭偏仪结果表明，C4F8 和 C6F6 在各自特定的原子层蚀刻窗口中均可获得可接受的原子层蚀刻特性，而 C6F6 则显示出更优越的原子层蚀刻性能。随后，根据等离子体的自由基密度、电子密度和等离子体电位诊断，对不同前驱体的 ALE 性能进行了研究，结果表明，不同前驱体自由基组成的差异会显著影响所产生的 ALE 趋势，而且 C6F6 的优异 ALE 性能可能源于其显著的聚合物特性。我们希望本研究结果有助于在蚀刻过程中更广泛地采用全球升温潜能值较低的前驱体。
{"title":"Plasma atomic layer etching of SiO2 with a low global warming potential fluorocarbon precursor (C6F6)","authors":"Inho Seong, Ye-bin You, Youngseok Lee, M. Choi, Dain Sung, Geunyoung Yeom, Shinjae You","doi":"10.1116/6.0003345","DOIUrl":"https://doi.org/10.1116/6.0003345","url":null,"abstract":"Reducing greenhouse gas emissions from semiconductor manufacturing has been attracting enormous interest in both industry and academia as global warming issues have increased in significance year by year. Among various strategies, the search for etch precursors that have low global warming potential is actively underway worldwide to reduce the use of conventional precursors with high global warming potential. In this paper, we explore the use of C6F6, a promising candidate to replace the widely utilized perfluorocarbon precursor C4F8, for plasma atomic layer etching (ALE) of SiO2. In situ ellipsometry results indicated that acceptable ALE characteristics were obtained with C4F8 and C6F6 each in their own specific ALE window, while C6F6 showed superior ALE performance. Investigation into the ALE performance with different precursors was then conducted based on plasma diagnostics for radical density, electron density, and plasma potential, and the results of which showed that the difference in the radical composition between precursors significantly affected the resulting ALE trends and also that the excellent ALE performance with C6F6 might originate from its significant polymeric characteristics. We expect the present findings to contribute to the wider adoption of low global warming potential precursors in the etching process.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"14 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140696641","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yu Huang, T. Nguyen, N. Dang, Hao-Yu Wang, Ming-Tzer Lin
In this study, copper/tungsten (Cu/W) and copper/chromium (Cu/Cr) multilayers were created by stacking bilayer films in a 3:1 ratio, with layer thicknesses ranging from 400 to 800 nm, deposited on Si (100) substrates using high power impulse magnetron sputtering (HiPIMS). The microstructural and surface properties of these films were examined through x-ray diffraction, atomic force microscopy, and scanning electron microscopy. Electrical properties were assessed using a four-point probe, while mechanical properties were measured via nanoindentation. Both multilayer systems showed a decrease in the hardness accompanied by an increase in the elastic modulus with each stacking bilayer. The Cu/W system experienced a gradual hardness reduction (down to 19%), compared to the Cu/Cr system, which exhibited a similar decrease (14.5%). The Cu/W and Cu/Cr multilayer film samples consistently demonstrate a softer nature compared to their bilayer counterparts due to the influence of the underlying Cu soft layers. A distinctive surface smoothness in these multilayer systems correlates with the elastic modulus in a manner unlike that with hardness. These multilayer films also demonstrated altered electrical resistivity, enhancing our understanding and capabilities in fabricating films with an increased number of layers.
{"title":"Materials’ properties of low temperature deposited Cu/W and Cu/Cr multilayer thin films using high power impulse magnetron sputtering","authors":"Yu Huang, T. Nguyen, N. Dang, Hao-Yu Wang, Ming-Tzer Lin","doi":"10.1116/6.0003512","DOIUrl":"https://doi.org/10.1116/6.0003512","url":null,"abstract":"In this study, copper/tungsten (Cu/W) and copper/chromium (Cu/Cr) multilayers were created by stacking bilayer films in a 3:1 ratio, with layer thicknesses ranging from 400 to 800 nm, deposited on Si (100) substrates using high power impulse magnetron sputtering (HiPIMS). The microstructural and surface properties of these films were examined through x-ray diffraction, atomic force microscopy, and scanning electron microscopy. Electrical properties were assessed using a four-point probe, while mechanical properties were measured via nanoindentation. Both multilayer systems showed a decrease in the hardness accompanied by an increase in the elastic modulus with each stacking bilayer. The Cu/W system experienced a gradual hardness reduction (down to 19%), compared to the Cu/Cr system, which exhibited a similar decrease (14.5%). The Cu/W and Cu/Cr multilayer film samples consistently demonstrate a softer nature compared to their bilayer counterparts due to the influence of the underlying Cu soft layers. A distinctive surface smoothness in these multilayer systems correlates with the elastic modulus in a manner unlike that with hardness. These multilayer films also demonstrated altered electrical resistivity, enhancing our understanding and capabilities in fabricating films with an increased number of layers.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"14 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140695746","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Elise des Ligneris, D. Samélor, A. Sekkat, Claudie Josse, T. Hungria, Alessandro Pugliara, C. Vahlas, B. Caussat
Deposition of silica-based thin films on carbon microfibers has long been considered a challenge. Indeed, the oxidation-sensitive nature of carbon microfibers over 550 K and their submicron-textured surface does not bode well with the required conformity of deposition best obtained by atomic layer deposition (ALD) and the thermal oxidative conditions associated with common protocols of silica ALD. Nonetheless, the use of a catalytic ALD process allowed for the deposition of amorphous alumina–silica bilayers from 445 K using trimethylaluminium and tris(tert-pentoxy)silanol (TPS). In this study, first undertaken on flat silicon wafers to make use of optical spectroscopies, the interplay between kinetics leading to a dense silica film growth was investigated in relation to the applied operation parameters. A threshold between the film catalyzed growth and the complete outgassing of pentoxy-derived compounds from TPS was found, resulting in a deposition of equivalent growth per cycle of 1.1 nm c−1, at a common ALD rate of 0.3 nm min−1, with a flat thickness gradient. The deposition on carbon microfiber fabrics was found conformal, albeit with a thickness growth capped below 20 nm, imparted by the microfiber surface texture. STEM-EDX showed a sharp interface of the bilayer with limited carbon diffusion. The conformal and dense deposition of alumina–silica thin films on carbon microfibers holds great potential for further use as refractory oxygen barrier layers.
{"title":"Catalytic atomic layer deposition of amorphous alumina–silica thin films on carbon microfibers","authors":"Elise des Ligneris, D. Samélor, A. Sekkat, Claudie Josse, T. Hungria, Alessandro Pugliara, C. Vahlas, B. Caussat","doi":"10.1116/6.0003422","DOIUrl":"https://doi.org/10.1116/6.0003422","url":null,"abstract":"Deposition of silica-based thin films on carbon microfibers has long been considered a challenge. Indeed, the oxidation-sensitive nature of carbon microfibers over 550 K and their submicron-textured surface does not bode well with the required conformity of deposition best obtained by atomic layer deposition (ALD) and the thermal oxidative conditions associated with common protocols of silica ALD. Nonetheless, the use of a catalytic ALD process allowed for the deposition of amorphous alumina–silica bilayers from 445 K using trimethylaluminium and tris(tert-pentoxy)silanol (TPS). In this study, first undertaken on flat silicon wafers to make use of optical spectroscopies, the interplay between kinetics leading to a dense silica film growth was investigated in relation to the applied operation parameters. A threshold between the film catalyzed growth and the complete outgassing of pentoxy-derived compounds from TPS was found, resulting in a deposition of equivalent growth per cycle of 1.1 nm c−1, at a common ALD rate of 0.3 nm min−1, with a flat thickness gradient. The deposition on carbon microfiber fabrics was found conformal, albeit with a thickness growth capped below 20 nm, imparted by the microfiber surface texture. STEM-EDX showed a sharp interface of the bilayer with limited carbon diffusion. The conformal and dense deposition of alumina–silica thin films on carbon microfibers holds great potential for further use as refractory oxygen barrier layers.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"126 16","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140709016","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
B. Cromer, D. Saraswat, N. Pieczulewski, W. Li, K. Nomoto, F. Hensling, K. Azizie, H. P. Nair, D. G. Schlom, D. Muller, D. Jena, H. Xing
β -Ga2O3 is actively touted as the next ultrawide bandgap material for power electronics. To fully utilize its high intrinsic critical electric field, development of high-quality robust large-barrier height junctions is essential. To this end, various high-work function metals, metal oxides, and hole-conducting oxides have been deposited on Ga2O3, primarily formed by sputter deposition. Unfortunately, reports to date indicate that measured barrier heights often deviate from the Schottky–Mott model as well as x-ray photoelectron spectroscopy (XPS) extractions of conduction band offsets, suggesting significant densities of electrically active defects at these junctions. We report Schottky diodes made from noble metal oxides, IrO2 and RuO2, deposited by ozone molecular beam epitaxy (ozone MBE) with barrier heights near 1.8 eV. These barriers show close agreement across extraction methods and robust to high surface electric fields upward of 6 MV/cm and 60 A/cm2 reverse current without degradation.
{"title":"Over 6 MV/cm operation in β-Ga2O3 Schottky barrier diodes with IrO2 and RuO2 anodes deposited by molecular beam epitaxy","authors":"B. Cromer, D. Saraswat, N. Pieczulewski, W. Li, K. Nomoto, F. Hensling, K. Azizie, H. P. Nair, D. G. Schlom, D. Muller, D. Jena, H. Xing","doi":"10.1116/6.0003468","DOIUrl":"https://doi.org/10.1116/6.0003468","url":null,"abstract":"β -Ga2O3 is actively touted as the next ultrawide bandgap material for power electronics. To fully utilize its high intrinsic critical electric field, development of high-quality robust large-barrier height junctions is essential. To this end, various high-work function metals, metal oxides, and hole-conducting oxides have been deposited on Ga2O3, primarily formed by sputter deposition. Unfortunately, reports to date indicate that measured barrier heights often deviate from the Schottky–Mott model as well as x-ray photoelectron spectroscopy (XPS) extractions of conduction band offsets, suggesting significant densities of electrically active defects at these junctions. We report Schottky diodes made from noble metal oxides, IrO2 and RuO2, deposited by ozone molecular beam epitaxy (ozone MBE) with barrier heights near 1.8 eV. These barriers show close agreement across extraction methods and robust to high surface electric fields upward of 6 MV/cm and 60 A/cm2 reverse current without degradation.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"709 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140718916","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lithium lanthanum tantalate (Li3xLa1/3−xTaO3, x = 0.075) thin films were grown via pulsed laser deposition using background gas atmospheres with varying partial pressures of oxygen and argon. The background gas composition was varied from 100% to 6.6% oxygen, with the pressure fixed at 150 mTorr. The maximum ion conductivity of 1.5 × 10−6 S/cm was found for the film deposited in 100% oxygen. The ion conductivity of the films was found to decrease with reduced oxygen content from 100% to 16.6% O2 in the background gas. The 6.6% oxygen background condition produced ion conductivity that approached that of the 100% oxygen condition film. The lithium transfer from the target to the film was found to decrease monotonically with decreasing oxygen content in the background gas but did not account for all changes in the ion conductivity. The activation energy of ion conduction was measured and found to correlate well with the measured ion conductivity trends. Analysis of x-ray diffraction results revealed that the films also exhibited a change in the lattice parameter that directly correlated with the ion conduction activation energy, indicating that a primary factor for determining the conductivity of these films is the changing size of the ion conduction bottleneck, which controls the activation energy of ion conduction.
{"title":"Effect of background gas composition on the stoichiometry and lithium ion conductivity of pulse laser deposited epitaxial lithium lanthanum tantalate (Li3xLa1/3−xTaO3)","authors":"Ian A. Brummel, Chuanzhen Zhou, J. Ihlefeld","doi":"10.1116/6.0003457","DOIUrl":"https://doi.org/10.1116/6.0003457","url":null,"abstract":"Lithium lanthanum tantalate (Li3xLa1/3−xTaO3, x = 0.075) thin films were grown via pulsed laser deposition using background gas atmospheres with varying partial pressures of oxygen and argon. The background gas composition was varied from 100% to 6.6% oxygen, with the pressure fixed at 150 mTorr. The maximum ion conductivity of 1.5 × 10−6 S/cm was found for the film deposited in 100% oxygen. The ion conductivity of the films was found to decrease with reduced oxygen content from 100% to 16.6% O2 in the background gas. The 6.6% oxygen background condition produced ion conductivity that approached that of the 100% oxygen condition film. The lithium transfer from the target to the film was found to decrease monotonically with decreasing oxygen content in the background gas but did not account for all changes in the ion conductivity. The activation energy of ion conduction was measured and found to correlate well with the measured ion conductivity trends. Analysis of x-ray diffraction results revealed that the films also exhibited a change in the lattice parameter that directly correlated with the ion conduction activation energy, indicating that a primary factor for determining the conductivity of these films is the changing size of the ion conduction bottleneck, which controls the activation energy of ion conduction.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"358 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140719348","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shikhar Arvind, Esben W. Larsen, Philippe Bezard, John Petersen, S. de Gendt
State-of-the-art extreme ultraviolet lithography requires the use of ultrathin photoresists (or resists) due to pattern stability concerns and reduced depth of focus of the extreme ultraviolet lithography scanners. Current resists for extreme ultraviolet lithography are less than 50 nm thick. These ultrathin resists further complicate pattern transfer as unintended plasma-induced damage during dry etching is more pronounced. A better understanding of the interaction of plasma species with ultrathin resists is critical for enabling pattern transfer of sub-10 nm features. Here, we study the impact of vacuum ultraviolet photons, argon ions, and argon plasma on a 40 nm thick polymethylmethacrylate film. Using a deuterium lamp, an industrial ion beam etch tool, and an industrial inductively coupled plasma etch tool, we exposed the polymer to photons, ions, and plasma, respectively. The exposed samples were then analyzed for chemical and physical changes using different characterization techniques. It was observed that the vacuum ultraviolet photons interact with the entire bulk of polymer film, while the ions only affect the surface and subsurface region. The photon exposed samples formed smaller polymer fragments at low exposure doses and further started to cross-link at high doses. In contrast, the ion modification leads to carbonization of only the top few nanometers of the polymer film, leaving the bottom bulk intact. The plasma exposed sample showed changes characteristic to both vacuum ultraviolet photons and ions and their synergism. It was stratified with a 1.34 ± 0.03 nm thick ion-caused carbonized layer on top of a 13.25 ± 0.12 nm photon-induced cross-linked layer. By studying the impact of plasma photons on ultrathin polymethylmethacrylate, we were able to establish a baseline for a testing methodology that can be extended to novel ultrathin resist platforms.
{"title":"Impact of vacuum ultraviolet photons on ultrathin polymethylmethacrylate during plasma etching","authors":"Shikhar Arvind, Esben W. Larsen, Philippe Bezard, John Petersen, S. de Gendt","doi":"10.1116/6.0003541","DOIUrl":"https://doi.org/10.1116/6.0003541","url":null,"abstract":"State-of-the-art extreme ultraviolet lithography requires the use of ultrathin photoresists (or resists) due to pattern stability concerns and reduced depth of focus of the extreme ultraviolet lithography scanners. Current resists for extreme ultraviolet lithography are less than 50 nm thick. These ultrathin resists further complicate pattern transfer as unintended plasma-induced damage during dry etching is more pronounced. A better understanding of the interaction of plasma species with ultrathin resists is critical for enabling pattern transfer of sub-10 nm features. Here, we study the impact of vacuum ultraviolet photons, argon ions, and argon plasma on a 40 nm thick polymethylmethacrylate film. Using a deuterium lamp, an industrial ion beam etch tool, and an industrial inductively coupled plasma etch tool, we exposed the polymer to photons, ions, and plasma, respectively. The exposed samples were then analyzed for chemical and physical changes using different characterization techniques. It was observed that the vacuum ultraviolet photons interact with the entire bulk of polymer film, while the ions only affect the surface and subsurface region. The photon exposed samples formed smaller polymer fragments at low exposure doses and further started to cross-link at high doses. In contrast, the ion modification leads to carbonization of only the top few nanometers of the polymer film, leaving the bottom bulk intact. The plasma exposed sample showed changes characteristic to both vacuum ultraviolet photons and ions and their synergism. It was stratified with a 1.34 ± 0.03 nm thick ion-caused carbonized layer on top of a 13.25 ± 0.12 nm photon-induced cross-linked layer. By studying the impact of plasma photons on ultrathin polymethylmethacrylate, we were able to establish a baseline for a testing methodology that can be extended to novel ultrathin resist platforms.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"83 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140720130","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
David R. Boris, Michael J. Johnson, Jeffrey M. Woodward, V. D. Wheeler, Scott G. Walton
Plasma enhanced atomic layer deposition (PEALD) is a cyclic atomic layer deposition (ALD) process that incorporates plasma-generated species into one of the cycle substeps. The addition of plasma is advantageous as it generally provides unique reactants and a substantially reduced growth temperature compared to thermal approaches. However, the inclusion of plasma, coupled with the increasing variety of plasma sources used in PEALD, can make these systems challenging to understand and control. This work focuses on the use of plasma diagnostics to examine the plasma characteristics of a remote inductively coupled plasma (ICP) source, a type of plasma source that is commonly used for PEALD. Ultraviolet to near-infrared spectroscopy and spatially resolved Langmuir probe measurements are employed to characterize a remote ICP system using nitrogen-based gas chemistries typical for III-nitride growth processes. Spectroscopy is used to characterize the relative concentrations of important reactive and energetic neutral species generated in the remote ICP as a function of gas flow rate, Ar/N2 flow fraction, and gas pressure. In addition, the plasma potential and plasma density for the same process parameters are examined using an RF compensated Langmuir probe downstream from the ICP source. The results are also discussed in terms of their impact on materials growth.
{"title":"Remote inductively coupled plasmas in Ar/N2 mixtures and implications for plasma enhanced ALD","authors":"David R. Boris, Michael J. Johnson, Jeffrey M. Woodward, V. D. Wheeler, Scott G. Walton","doi":"10.1116/6.0003538","DOIUrl":"https://doi.org/10.1116/6.0003538","url":null,"abstract":"Plasma enhanced atomic layer deposition (PEALD) is a cyclic atomic layer deposition (ALD) process that incorporates plasma-generated species into one of the cycle substeps. The addition of plasma is advantageous as it generally provides unique reactants and a substantially reduced growth temperature compared to thermal approaches. However, the inclusion of plasma, coupled with the increasing variety of plasma sources used in PEALD, can make these systems challenging to understand and control. This work focuses on the use of plasma diagnostics to examine the plasma characteristics of a remote inductively coupled plasma (ICP) source, a type of plasma source that is commonly used for PEALD. Ultraviolet to near-infrared spectroscopy and spatially resolved Langmuir probe measurements are employed to characterize a remote ICP system using nitrogen-based gas chemistries typical for III-nitride growth processes. Spectroscopy is used to characterize the relative concentrations of important reactive and energetic neutral species generated in the remote ICP as a function of gas flow rate, Ar/N2 flow fraction, and gas pressure. In addition, the plasma potential and plasma density for the same process parameters are examined using an RF compensated Langmuir probe downstream from the ICP source. The results are also discussed in terms of their impact on materials growth.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"8 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140717346","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Qihang Li, Jinping Luo, Zaoyang Li, M. Rummeli, Lijun Liu
Chemical vapor deposition (CVD) is an affordable method for the preparation of large-scale and high-quality graphene. With the increase in CVD reactor size, gas mass transfer, flow state, and gas phase dynamics become more complicated. In this study, computational fluid dynamics is used to investigate factors affecting the uniformity of large-scale graphene growth under different growth conditions and reactor configurations. The dimensionless number defined in this paper and the Grashof number are utilized to distinguish the species transfer patterns and the flow states, respectively. A gas-surface dynamics model is established to simulate the graphene growth. Results reveal that the graphene growth rate uniformity is the highest at very low pressure and flow rate due to the flow symmetry and diffusion-dominated species transfer. At an increased pressure of 20 Torr, the uniformity of the graphene growth rate becomes higher axially and lower circumferentially with an increasing inlet mass flow rate. When the flow rate is fixed at 1500 SCCM and pressure is reduced from 20 to 2 Torr, graphene growth uniformity first increases and then decreases due to the influence of gas phase dynamics. Graphene growth rates are analyzed across ordinary reactor configurations and four configurations with inner tubes at 20 Torr pressure and 1500 SCCM flow rate. Comprehensive evaluation suggests that the ordinary reactor configuration performs best under these conditions. This research offers insights into the macroscopic growth mechanism of large-scale graphene and provides guidance for designing growth conditions in large-area graphene production.
{"title":"Effect of growth conditions and reactor configuration on the growth uniformity of large-scale graphene by chemical vapor deposition","authors":"Qihang Li, Jinping Luo, Zaoyang Li, M. Rummeli, Lijun Liu","doi":"10.1116/6.0003487","DOIUrl":"https://doi.org/10.1116/6.0003487","url":null,"abstract":"Chemical vapor deposition (CVD) is an affordable method for the preparation of large-scale and high-quality graphene. With the increase in CVD reactor size, gas mass transfer, flow state, and gas phase dynamics become more complicated. In this study, computational fluid dynamics is used to investigate factors affecting the uniformity of large-scale graphene growth under different growth conditions and reactor configurations. The dimensionless number defined in this paper and the Grashof number are utilized to distinguish the species transfer patterns and the flow states, respectively. A gas-surface dynamics model is established to simulate the graphene growth. Results reveal that the graphene growth rate uniformity is the highest at very low pressure and flow rate due to the flow symmetry and diffusion-dominated species transfer. At an increased pressure of 20 Torr, the uniformity of the graphene growth rate becomes higher axially and lower circumferentially with an increasing inlet mass flow rate. When the flow rate is fixed at 1500 SCCM and pressure is reduced from 20 to 2 Torr, graphene growth uniformity first increases and then decreases due to the influence of gas phase dynamics. Graphene growth rates are analyzed across ordinary reactor configurations and four configurations with inner tubes at 20 Torr pressure and 1500 SCCM flow rate. Comprehensive evaluation suggests that the ordinary reactor configuration performs best under these conditions. This research offers insights into the macroscopic growth mechanism of large-scale graphene and provides guidance for designing growth conditions in large-area graphene production.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"195 S562","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140730753","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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