Windows for vacuum ultraviolet (VUV) sources are valuable for many applications but difficult to fabricate due to most materials being too absorptive at VUV wavelengths. We have designed, fabricated, and characterized a carbon nanotube (CNT) collimator as a window with high (VUV) transmission and significant differential pumping. The CNT collimators are arrays of square channels of various dimensions and height with sidewalls composed of vertically aligned CNT forests. The CNT collimators in this work exhibited peak intensity transmissions for VUV light (58.4 nm) of 18%–37% of that reported for the same system without a collimator present [S. Olsen, D. Allred, and R. Vanfleet, J. Vac. Sci. Technol. A (2024)]. Further analysis found that the peak intensity transmissions were lowered due to carbon deposition on the phosphor viewing screen from contaminants. The CNT collimator also had significant sidewall reflection in the VUV range (R=0.21±0.08 in the VUV range for angles 15.6 degrees and below). Pressure ratios (low pressure over high pressure) in the VUV transmission experiment were dominated by leaks in the alignment mechanism. Additional experiments demonstrated the CNT collimator’s reflection and superior differential pumping with pressure ratios less than 0.001.
{"title":"Carbon nanotube collimator as an vacuum ultraviolet window","authors":"S. C. Olsen, D. D. Allred, R. R. Vanfleet","doi":"10.1116/6.0003675","DOIUrl":"https://doi.org/10.1116/6.0003675","url":null,"abstract":"Windows for vacuum ultraviolet (VUV) sources are valuable for many applications but difficult to fabricate due to most materials being too absorptive at VUV wavelengths. We have designed, fabricated, and characterized a carbon nanotube (CNT) collimator as a window with high (VUV) transmission and significant differential pumping. The CNT collimators are arrays of square channels of various dimensions and height with sidewalls composed of vertically aligned CNT forests. The CNT collimators in this work exhibited peak intensity transmissions for VUV light (58.4 nm) of 18%–37% of that reported for the same system without a collimator present [S. Olsen, D. Allred, and R. Vanfleet, J. Vac. Sci. Technol. A (2024)]. Further analysis found that the peak intensity transmissions were lowered due to carbon deposition on the phosphor viewing screen from contaminants. The CNT collimator also had significant sidewall reflection in the VUV range (R=0.21±0.08 in the VUV range for angles 15.6 degrees and below). Pressure ratios (low pressure over high pressure) in the VUV transmission experiment were dominated by leaks in the alignment mechanism. Additional experiments demonstrated the CNT collimator’s reflection and superior differential pumping with pressure ratios less than 0.001.","PeriodicalId":282302,"journal":{"name":"Journal of Vacuum Science & Technology B","volume":"63 11","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141348112","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}
A variable axis lens (VAL) concept has been demonstrated an effective method to reduce aberrations of electron beam machines and has been explored to several configurations. To implement the advantages of VAL fully, it is desirable to make the axial potential distribution of the objective lens match the deflection functions of deflectors well. To our knowledge, the electrostatic deflectors applied in electron-optical systems based on VAL concept are all constructed with a “cylindrical” shape. However, when a magnetic objective lens in the VAL configurations is constructed with different radii of upper and lower pole pieces, there is a mismatch between the asymmetric lens and cylindrical deflectors, which would lead to a significant increase in aberrations. With this in mind, we have developed tapered deflectors to address the foregoing problem. A comparative study on variable axis lens systems based on conventional cylindrical deflectors and the proposed tapered ones is undertaken. Simulation results demonstrate the validity and effectiveness of the proposed VALs to reduce aberrations and an electron beam landing angle.
可变轴透镜（VAL）概念已被证明是减少电子束机器像差的有效方法，并已被应用于多种配置中。为了充分发挥 VAL 的优势，最好能使物镜的轴向电势分布与偏转器的偏转功能相匹配。据我们所知，基于 VAL 概念应用于电子光学系统的静电偏转器都是 "圆柱形 "的。然而，当 VAL 配置中的磁性物镜的上下极片半径不同时，不对称透镜和圆柱形偏转器之间就会出现不匹配，从而导致像差显著增加。有鉴于此，我们开发了锥形偏转器来解决上述问题。我们对基于传统圆柱形偏转器和所提出的锥形偏转器的变轴透镜系统进行了比较研究。仿真结果证明了所提出的变轴透镜在减少像差和电子束着陆角方面的有效性和有效性。
{"title":"Comparative study on variable axis lens systems based on tapered deflectors","authors":"Qingmao Zhang, Qirui Wang, Delong Chen, Junbiao Liu, Yanjun Zhang, Quantong Li, Zhuming Liu","doi":"10.1116/6.0003605","DOIUrl":"https://doi.org/10.1116/6.0003605","url":null,"abstract":"A variable axis lens (VAL) concept has been demonstrated an effective method to reduce aberrations of electron beam machines and has been explored to several configurations. To implement the advantages of VAL fully, it is desirable to make the axial potential distribution of the objective lens match the deflection functions of deflectors well. To our knowledge, the electrostatic deflectors applied in electron-optical systems based on VAL concept are all constructed with a “cylindrical” shape. However, when a magnetic objective lens in the VAL configurations is constructed with different radii of upper and lower pole pieces, there is a mismatch between the asymmetric lens and cylindrical deflectors, which would lead to a significant increase in aberrations. With this in mind, we have developed tapered deflectors to address the foregoing problem. A comparative study on variable axis lens systems based on conventional cylindrical deflectors and the proposed tapered ones is undertaken. Simulation results demonstrate the validity and effectiveness of the proposed VALs to reduce aberrations and an electron beam landing angle.","PeriodicalId":282302,"journal":{"name":"Journal of Vacuum Science & Technology B","volume":"33 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141350029","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}
The modified Knudsen equation was developed to calculate the gas flow rate through a cylindrical tube with arbitrary length-to-diameter ratio in any flow regime including molecular flow, viscous laminar flow, turbulent flow, critical flow, subcritical flow, and their intermediates in our laboratory. Here, it is upgraded for better agreement with literature data, and the upgraded version is compared with 83 literature sources including 31 gas flow equations to verify its reliability. For Kn > 10−5, the modified Knudsen equation mostly agrees with the literature data to within 20%, except for orifice flows with pd/pu ≈ 1.
{"title":"Upgrading of the modified Knudsen equation and its verification for calculating the gas flow rate through cylindrical tubes","authors":"Hajime Yoshida","doi":"10.1116/6.0003581","DOIUrl":"https://doi.org/10.1116/6.0003581","url":null,"abstract":"The modified Knudsen equation was developed to calculate the gas flow rate through a cylindrical tube with arbitrary length-to-diameter ratio in any flow regime including molecular flow, viscous laminar flow, turbulent flow, critical flow, subcritical flow, and their intermediates in our laboratory. Here, it is upgraded for better agreement with literature data, and the upgraded version is compared with 83 literature sources including 31 gas flow equations to verify its reliability. For Kn > 10−5, the modified Knudsen equation mostly agrees with the literature data to within 20%, except for orifice flows with pd/pu ≈ 1.","PeriodicalId":282302,"journal":{"name":"Journal of Vacuum Science & Technology B","volume":"37 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141354203","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}
X. Huang, S. Q. Lim, T. Ratcliff, L. Smillie, G. J. Grzybowski, B. Claflin, J. Warrender, J. S. Williams
Thin films of germanium-tin (GeSn) alloy with Sn content well above its equilibrium solubility limit in Ge are produced using both remote plasma-enhanced chemical vapor deposition (RPECVD) directly on silicon substrates and ion implantation of Sn into Ge. For RPECVD, the growth temperature of 302 °C resulted in fully relaxed GeSn alloys with high defect density, principally threading dislocations related to the large lattice mismatch between Si and GeSn. For the implantation case, pulsed laser melting was used to melt and crystallize the GeSn layer on a time scale of a few tens of nanoseconds. The resulting GeSn layers were also relaxed and defective, presumably again as a result of lattice mismatch with the underlying Ge lattice. However, the nature of the defects was quite different to the RPECVD method, whereby the line defects were not threading dislocations but stackinglike defects, which developed into arrays of these defects in the high Sn content region close to the surface. For the purpose of comparing RPECVD and ion-implantation methods, alloy films of similar thickness (400–450 nm) and Sn content (4.5–6.5 at. %) were examined. Film parameters (thickness, Sn content, Sn solubility, and segregation), as well as film quality and defect structures, were examined for both fabrication methods using several analytical techniques. This comparison provided us with a better physical understanding of our GeSn films and will help inform future growth/fabrication strategies targeted at minimizing defects formed in the GeSn films for the realization of optoelectronic devices.
利用直接在硅衬底上进行远程等离子体增强化学气相沉积（RPECVD）和将锡离子注入到 Ge 中两种方法，制备出了锡含量远高于其在 Ge 中平衡溶解极限的锗锡合金（GeSn）薄膜。就 RPECVD 而言，302 °C 的生长温度产生了具有高缺陷密度的完全松弛 GeSn 合金，主要是与硅和 GeSn 之间的巨大晶格失配有关的穿线位错。在植入情况下，使用脉冲激光熔化在几十纳秒的时间尺度内熔化和结晶 GeSn 层。由此产生的 GeSn 层也出现松弛和缺陷，这可能也是由于与底层 Ge 晶格不匹配造成的。然而，缺陷的性质与 RPECVD 方法截然不同，其中的线缺陷不是穿线位错，而是堆积缺陷，在靠近表面的高锡含量区域发展成这些缺陷的阵列。为了比较 RPECVD 法和离子注入法，对厚度（400-450 nm）和含 Sn 量（4.5-6.5 at.使用多种分析技术对两种制造方法的薄膜参数（厚度、锡含量、锡溶解度和偏析）以及薄膜质量和缺陷结构进行了检测。通过比较，我们对 GeSn 薄膜的物理特性有了更好的了解，这将有助于为未来的生长/制造策略提供依据，从而最大限度地减少 GeSn 薄膜中形成的缺陷，实现光电设备的制造。
{"title":"Comparison of GeSn alloy films prepared by ion implantation and remote plasma-enhanced chemical vapor deposition methods","authors":"X. Huang, S. Q. Lim, T. Ratcliff, L. Smillie, G. J. Grzybowski, B. Claflin, J. Warrender, J. S. Williams","doi":"10.1116/6.0003668","DOIUrl":"https://doi.org/10.1116/6.0003668","url":null,"abstract":"Thin films of germanium-tin (GeSn) alloy with Sn content well above its equilibrium solubility limit in Ge are produced using both remote plasma-enhanced chemical vapor deposition (RPECVD) directly on silicon substrates and ion implantation of Sn into Ge. For RPECVD, the growth temperature of 302 °C resulted in fully relaxed GeSn alloys with high defect density, principally threading dislocations related to the large lattice mismatch between Si and GeSn. For the implantation case, pulsed laser melting was used to melt and crystallize the GeSn layer on a time scale of a few tens of nanoseconds. The resulting GeSn layers were also relaxed and defective, presumably again as a result of lattice mismatch with the underlying Ge lattice. However, the nature of the defects was quite different to the RPECVD method, whereby the line defects were not threading dislocations but stackinglike defects, which developed into arrays of these defects in the high Sn content region close to the surface. For the purpose of comparing RPECVD and ion-implantation methods, alloy films of similar thickness (400–450 nm) and Sn content (4.5–6.5 at. %) were examined. Film parameters (thickness, Sn content, Sn solubility, and segregation), as well as film quality and defect structures, were examined for both fabrication methods using several analytical techniques. This comparison provided us with a better physical understanding of our GeSn films and will help inform future growth/fabrication strategies targeted at minimizing defects formed in the GeSn films for the realization of optoelectronic devices.","PeriodicalId":282302,"journal":{"name":"Journal of Vacuum Science & Technology B","volume":"32 23","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141354742","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}
Haochen Zhao, Suho Park, Guangyang Lin, Yuying Zhang, Tuofu Zhama, Chandan Samanta, Lorry Chang, Xiaofeng Zhu, Xu Feng, Kevin O. Díaz-Aponte, Lin Cong, Yuping Zeng
We experimentally demonstrate a low-cost transfer process of GeSn ribbons to insulating substrates for short-wave infrared (SWIR) sensing/imaging applications. By releasing the original compressive GeSn layer to nearly fully relaxed state GeSn ribbons, the room-temperature spectral response of the photodetector is further extended to 3.2 μm, which can cover the entire SWIR range. Compared with the as-grown GeSn reference photodetectors, the fabricated GeSn ribbon photodetectors have a fivefold improvement in the light-to-dark current ratio, which can improve the detectivity for high-performance photodetection. The transient performance of a GeSn ribbon photodetector is investigated with a rise time of about 40 μs, which exceeds the response time of most GeSn (Ge)-related devices. In addition, this transfer process can be applied on various substrates, making it a versatile technology that can be used for various applications ranging from optoelectronics to large-area electronics. These results provide insightful guidance for the development of low-cost and high-speed SWIR photodetectors based on Sn-containing group IV low-dimensional structures.
{"title":"Transferable GeSn ribbon photodetectors for high-speed short-wave infrared photonic applications","authors":"Haochen Zhao, Suho Park, Guangyang Lin, Yuying Zhang, Tuofu Zhama, Chandan Samanta, Lorry Chang, Xiaofeng Zhu, Xu Feng, Kevin O. Díaz-Aponte, Lin Cong, Yuping Zeng","doi":"10.1116/6.0003561","DOIUrl":"https://doi.org/10.1116/6.0003561","url":null,"abstract":"We experimentally demonstrate a low-cost transfer process of GeSn ribbons to insulating substrates for short-wave infrared (SWIR) sensing/imaging applications. By releasing the original compressive GeSn layer to nearly fully relaxed state GeSn ribbons, the room-temperature spectral response of the photodetector is further extended to 3.2 μm, which can cover the entire SWIR range. Compared with the as-grown GeSn reference photodetectors, the fabricated GeSn ribbon photodetectors have a fivefold improvement in the light-to-dark current ratio, which can improve the detectivity for high-performance photodetection. The transient performance of a GeSn ribbon photodetector is investigated with a rise time of about 40 μs, which exceeds the response time of most GeSn (Ge)-related devices. In addition, this transfer process can be applied on various substrates, making it a versatile technology that can be used for various applications ranging from optoelectronics to large-area electronics. These results provide insightful guidance for the development of low-cost and high-speed SWIR photodetectors based on Sn-containing group IV low-dimensional structures.","PeriodicalId":282302,"journal":{"name":"Journal of Vacuum Science & Technology B","volume":"126 10","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141351818","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}
Hoon-Ki Lee, V. Janardhanam, Woojin Chang, K. Cho, Chel-Jong Choi, Jae Kyoung Mun
In this study, the (001) β-Ga2O3 surface was dry etched employing the inductively coupled plasma-reactive ion etching (ICP-RIE) system, and Au/Ni/β-Ga2O3 Schottky barrier diodes (SBDs) were fabricated on the etched surface. The impact of ion bombardment on the (001) β-Ga2O3 surface during dry etching and its effect on current-voltage (I–V) characteristics and breakdown voltage was investigated. The forward current at higher bias decreased with increasing temperature due to the fact that the higher temperatures cause them to be less mobile owing to the scattering effects that reduce the on-current. The temperature-dependent I–V characterization of the Au/Ni/β-Ga2O3 SBD revealed a strong temperature dependence of barrier height and ideality factor associated with the barrier height inhomogeneity at the interface between Ni and β-Ga2O3. Analysis of the barrier height inhomogeneities with the assumption of Gaussian distribution of barrier heights confirmed the presence of a double Gaussian barrier distribution having mean barrier heights of 0.71 and 1.21 eV in the temperature range of (83–158) and (183–283 K), respectively. The Richardson constant value obtained from the modified Richardson plot interpreted with the consideration of Gaussian distribution of barrier heights closely matched with the theoretical value of β-Ga2O3. The fabricated Au/Ni/β-Ga2O3 SBD showed consistent breakdown voltage in the range of 670–695 V over repeated measurements with a time interval of 1 min without exhibiting any damage. However, after an initial breakdown voltage measurement, repeating the measurement with a 30 s interval led to an exponential increase in current, leading to the destruction of the device, associated with the low thermal conductivity of the substrate. The results obtained reveal that the ICP-RIE dry etching did not cause significant damage to the surface.
{"title":"Effect of inductively coupled plasma etch on the interface barrier behavior of (001) β-Ga2O3 Schottky barrier diode","authors":"Hoon-Ki Lee, V. Janardhanam, Woojin Chang, K. Cho, Chel-Jong Choi, Jae Kyoung Mun","doi":"10.1116/6.0003608","DOIUrl":"https://doi.org/10.1116/6.0003608","url":null,"abstract":"In this study, the (001) β-Ga2O3 surface was dry etched employing the inductively coupled plasma-reactive ion etching (ICP-RIE) system, and Au/Ni/β-Ga2O3 Schottky barrier diodes (SBDs) were fabricated on the etched surface. The impact of ion bombardment on the (001) β-Ga2O3 surface during dry etching and its effect on current-voltage (I–V) characteristics and breakdown voltage was investigated. The forward current at higher bias decreased with increasing temperature due to the fact that the higher temperatures cause them to be less mobile owing to the scattering effects that reduce the on-current. The temperature-dependent I–V characterization of the Au/Ni/β-Ga2O3 SBD revealed a strong temperature dependence of barrier height and ideality factor associated with the barrier height inhomogeneity at the interface between Ni and β-Ga2O3. Analysis of the barrier height inhomogeneities with the assumption of Gaussian distribution of barrier heights confirmed the presence of a double Gaussian barrier distribution having mean barrier heights of 0.71 and 1.21 eV in the temperature range of (83–158) and (183–283 K), respectively. The Richardson constant value obtained from the modified Richardson plot interpreted with the consideration of Gaussian distribution of barrier heights closely matched with the theoretical value of β-Ga2O3. The fabricated Au/Ni/β-Ga2O3 SBD showed consistent breakdown voltage in the range of 670–695 V over repeated measurements with a time interval of 1 min without exhibiting any damage. However, after an initial breakdown voltage measurement, repeating the measurement with a 30 s interval led to an exponential increase in current, leading to the destruction of the device, associated with the low thermal conductivity of the substrate. The results obtained reveal that the ICP-RIE dry etching did not cause significant damage to the surface.","PeriodicalId":282302,"journal":{"name":"Journal of Vacuum Science & Technology B","volume":" 8","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141373897","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}
G. Oehrlein, Stephan M. Brandstadter, Robert L. Bruce, Jane P. Chang, Jessica C. DeMott, Vincent M. Donnelly, Rémi Dussart, Andreas Fischer, R. Gottscho, S. Hamaguchi, M. Honda, Masaru Hori, Kenji Ishikawa, Steven G. Jaloviar, K. J. Kanarik, K. Karahashi, Akiteru Ko, Hiten Kothari, Nobuyuki Kuboi, M. Kushner, T. Lill, P. Luan, Ali Mesbah, Eric Miller, Shoubhanik Nath, Y. Ohya, M. Omura, C. Park, John Poulose, Shahid Rauf, M. Sekine, Taylor G. Smith, Nathan Stafford, Theo Standaert, P. Ventzek
Plasma etching is an essential semiconductor manufacturing technology required to enable the current microelectronics industry. Along with lithographic patterning, thin-film formation methods, and others, plasma etching has dynamically evolved to meet the exponentially growing demands of the microelectronics industry that enables modern society. At this time, plasma etching faces a period of unprecedented changes owing to numerous factors, including aggressive transition to three-dimensional (3D) device architectures, process precision approaching atomic-scale critical dimensions, introduction of new materials, fundamental silicon device limits, and parallel evolution of post-CMOS approaches. The vast growth of the microelectronics industry has emphasized its role in addressing major societal challenges, including questions on the sustainability of the associated energy use, semiconductor manufacturing related emissions of greenhouse gases, and others. The goal of this article is to help both define the challenges for plasma etching and point out effective plasma etching technology options that may play essential roles in defining microelectronics manufacturing in the future. The challenges are accompanied by significant new opportunities, including integrating experiments with various computational approaches such as machine learning/artificial intelligence and progress in computational approaches, including the realization of digital twins of physical etch chambers through hybrid/coupled models. These prospects can enable innovative solutions to problems that were not available during the past 50 years of plasma etch development in the microelectronics industry. To elaborate on these perspectives, the present article brings together the views of various experts on the different topics that will shape plasma etching for microelectronics manufacturing of the future.
{"title":"Future of plasma etching for microelectronics: Challenges and opportunities","authors":"G. Oehrlein, Stephan M. Brandstadter, Robert L. Bruce, Jane P. Chang, Jessica C. DeMott, Vincent M. Donnelly, Rémi Dussart, Andreas Fischer, R. Gottscho, S. Hamaguchi, M. Honda, Masaru Hori, Kenji Ishikawa, Steven G. Jaloviar, K. J. Kanarik, K. Karahashi, Akiteru Ko, Hiten Kothari, Nobuyuki Kuboi, M. Kushner, T. Lill, P. Luan, Ali Mesbah, Eric Miller, Shoubhanik Nath, Y. Ohya, M. Omura, C. Park, John Poulose, Shahid Rauf, M. Sekine, Taylor G. Smith, Nathan Stafford, Theo Standaert, P. Ventzek","doi":"10.1116/6.0003579","DOIUrl":"https://doi.org/10.1116/6.0003579","url":null,"abstract":"Plasma etching is an essential semiconductor manufacturing technology required to enable the current microelectronics industry. Along with lithographic patterning, thin-film formation methods, and others, plasma etching has dynamically evolved to meet the exponentially growing demands of the microelectronics industry that enables modern society. At this time, plasma etching faces a period of unprecedented changes owing to numerous factors, including aggressive transition to three-dimensional (3D) device architectures, process precision approaching atomic-scale critical dimensions, introduction of new materials, fundamental silicon device limits, and parallel evolution of post-CMOS approaches. The vast growth of the microelectronics industry has emphasized its role in addressing major societal challenges, including questions on the sustainability of the associated energy use, semiconductor manufacturing related emissions of greenhouse gases, and others. The goal of this article is to help both define the challenges for plasma etching and point out effective plasma etching technology options that may play essential roles in defining microelectronics manufacturing in the future. The challenges are accompanied by significant new opportunities, including integrating experiments with various computational approaches such as machine learning/artificial intelligence and progress in computational approaches, including the realization of digital twins of physical etch chambers through hybrid/coupled models. These prospects can enable innovative solutions to problems that were not available during the past 50 years of plasma etch development in the microelectronics industry. To elaborate on these perspectives, the present article brings together the views of various experts on the different topics that will shape plasma etching for microelectronics manufacturing of the future.","PeriodicalId":282302,"journal":{"name":"Journal of Vacuum Science & Technology B","volume":" 14","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141373787","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}
Shohei Hayashi, A. Ito, T. Dougakiuchi, M. Hitaka, K. Fujita
Millimeter-wave difference frequency generation is reported for a dual-wavelength mid-infrared quantum cascade laser operating at room temperature. To overcome a low mid-infrared-to-terahertz conversion efficiency below 1 THz, a long-wavelength, high-performance mid-infrared quantum cascade laser structure with higher nonlinear susceptivity is adopted. By designing the efficient allocation of mid-infrared pumps to two sections of fabricated distributed feedback grating, a closely separated dual-wavelength (λ1 ∼ 13.53 μm and λ2 ∼ 13.39 μm) laser oscillation was obtained. Consequently, a millimeter-wave emission at a frequency of 231 GHz was successfully observed at room temperature.
{"title":"Millimeter-wave generation with a room-temperature nonlinear quantum cascade laser","authors":"Shohei Hayashi, A. Ito, T. Dougakiuchi, M. Hitaka, K. Fujita","doi":"10.1116/6.0003536","DOIUrl":"https://doi.org/10.1116/6.0003536","url":null,"abstract":"Millimeter-wave difference frequency generation is reported for a dual-wavelength mid-infrared quantum cascade laser operating at room temperature. To overcome a low mid-infrared-to-terahertz conversion efficiency below 1 THz, a long-wavelength, high-performance mid-infrared quantum cascade laser structure with higher nonlinear susceptivity is adopted. By designing the efficient allocation of mid-infrared pumps to two sections of fabricated distributed feedback grating, a closely separated dual-wavelength (λ1 ∼ 13.53 μm and λ2 ∼ 13.39 μm) laser oscillation was obtained. Consequently, a millimeter-wave emission at a frequency of 231 GHz was successfully observed at room temperature.","PeriodicalId":282302,"journal":{"name":"Journal of Vacuum Science & Technology B","volume":"344 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141385728","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}
O. Spitz, Y. B. Shuai, S. Zhao, P. Didier, D. Díaz-Thomas, A. N. Baranov, L. Cerutti, D. Rontani, J. Wu, F. Grillot
Nonlinear dynamics at mid-infrared wavelength is of interest for various applications but has been mainly limited to quantum cascade lasers so far. In this article, we show that interband cascade lasers can generate complex optical chaos with bandwidth in the GHz range and this outperforms the performances of quantum cascade laser chaos. The chaos nature of our signal is confirmed by a thorough time-series analysis. Modeling of the semiconductor laser under short-cavity external optical feedback allows confirming the high bias chaos operation that we observe experimentally. These results pave the way for applications at mid-infrared wavelength, such as private free-space communication.
{"title":"Generation of broadband optical chaos at mid-infrared wavelength with an interband cascade laser","authors":"O. Spitz, Y. B. Shuai, S. Zhao, P. Didier, D. Díaz-Thomas, A. N. Baranov, L. Cerutti, D. Rontani, J. Wu, F. Grillot","doi":"10.1116/6.0003572","DOIUrl":"https://doi.org/10.1116/6.0003572","url":null,"abstract":"Nonlinear dynamics at mid-infrared wavelength is of interest for various applications but has been mainly limited to quantum cascade lasers so far. In this article, we show that interband cascade lasers can generate complex optical chaos with bandwidth in the GHz range and this outperforms the performances of quantum cascade laser chaos. The chaos nature of our signal is confirmed by a thorough time-series analysis. Modeling of the semiconductor laser under short-cavity external optical feedback allows confirming the high bias chaos operation that we observe experimentally. These results pave the way for applications at mid-infrared wavelength, such as private free-space communication.","PeriodicalId":282302,"journal":{"name":"Journal of Vacuum Science & Technology B","volume":"162 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141040700","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}
Tyler T. McCarthy, Allison M. McMinn, Xiaoyang Liu, Razine Hossain, Xin Qi, Zheng Ju, Mark Mangus, Shui-Qing Yu, Yong-Hang Zhang
Pb based group-IV alloys such as GePb have been gaining interest as a potential alternative for infrared detectors, quantum materials, and high-speed electronic devices. Challenges remain in their growth due to the extremely low solid solubility of Pb in the Ge–Pb system. This paper reports molecular beam epitaxy growth of GePb alloy thin films on Ge(100) substrates. Effusion cells of Ge and Pb are used to control the flux ratio independently. The optimal substrate temperature is found to be near the thermocouple temperature of 300 °C based on the characterization of the grown films using high-resolution x-ray diffraction. A large change in the Ge:Pb beam equivalent pressure ratio from 10:1 to 1:1 results in only a minimal increase of the Pb composition from 0.74% to 2.84% as estimated from Raman spectroscopy and Rutherford backscattering spectrometry. Scanning electron microscopy images show a large volume of Pb islands on the surface that form into either long trapezoidal rods or uniform droplets, with increasing Pb flux and growth time the density of Pb islands increased.
{"title":"Molecular beam epitaxy growth and characterization of GePb alloys","authors":"Tyler T. McCarthy, Allison M. McMinn, Xiaoyang Liu, Razine Hossain, Xin Qi, Zheng Ju, Mark Mangus, Shui-Qing Yu, Yong-Hang Zhang","doi":"10.1116/6.0003567","DOIUrl":"https://doi.org/10.1116/6.0003567","url":null,"abstract":"Pb based group-IV alloys such as GePb have been gaining interest as a potential alternative for infrared detectors, quantum materials, and high-speed electronic devices. Challenges remain in their growth due to the extremely low solid solubility of Pb in the Ge–Pb system. This paper reports molecular beam epitaxy growth of GePb alloy thin films on Ge(100) substrates. Effusion cells of Ge and Pb are used to control the flux ratio independently. The optimal substrate temperature is found to be near the thermocouple temperature of 300 °C based on the characterization of the grown films using high-resolution x-ray diffraction. A large change in the Ge:Pb beam equivalent pressure ratio from 10:1 to 1:1 results in only a minimal increase of the Pb composition from 0.74% to 2.84% as estimated from Raman spectroscopy and Rutherford backscattering spectrometry. Scanning electron microscopy images show a large volume of Pb islands on the surface that form into either long trapezoidal rods or uniform droplets, with increasing Pb flux and growth time the density of Pb islands increased.","PeriodicalId":282302,"journal":{"name":"Journal of Vacuum Science & Technology B","volume":"165 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141050310","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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