Junsheng Lu, Yanan Zeng, X. Chang, Yujian Hong, Xiaodong Hu
Synthetic aperture has been a common method in digital holographic microscopy resolution enhancement over the years. Multiangle illumination is one type of synthetic aperture methods. Reconstructed phase errors appeared when synthesizing aperture not considering the difference between different inclined incident beams' reconstruction distances. To reduce phase errors, this paper proposes a method using different reconstruction distances in inclined incident beams to achieve synthetic aperture resolution enhancement. A multiangle illumination reflectance digital holographic microscopy system is built to prove this method. The reconstruction distances can be calculated theoretically to compute the phase image. The phase image errors can be remarkably reduced by using the proposed method by analyzing the experimental result.
{"title":"Phase errors reduction in multi-angle illumination digital holographic microscopy","authors":"Junsheng Lu, Yanan Zeng, X. Chang, Yujian Hong, Xiaodong Hu","doi":"10.1116/6.0000478","DOIUrl":"https://doi.org/10.1116/6.0000478","url":null,"abstract":"Synthetic aperture has been a common method in digital holographic microscopy resolution enhancement over the years. Multiangle illumination is one type of synthetic aperture methods. Reconstructed phase errors appeared when synthesizing aperture not considering the difference between different inclined incident beams' reconstruction distances. To reduce phase errors, this paper proposes a method using different reconstruction distances in inclined incident beams to achieve synthetic aperture resolution enhancement. A multiangle illumination reflectance digital holographic microscopy system is built to prove this method. The reconstruction distances can be calculated theoretically to compute the phase image. The phase image errors can be remarkably reduced by using the proposed method by analyzing the experimental result.","PeriodicalId":17652,"journal":{"name":"Journal of Vacuum Science & Technology. B. Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76090248","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}
I. Mahaboob, S. Novak, E. Rocco, K. Hogan, F. Shahedipour-Sandvik
In the current study, the electrical behavior of the AlGaN/GaN high electron mobility transistors (HEMTs) grown with an underlying GaN:Mg layer is detailed. It is shown that the activation of the buried p-GaN layer is achieved without hydrogen diffusion out of the layer. Reversal in the electrical behavior of the two-dimensional electron gas (2DEG) is also observed in the as-grown structure based on the p-GaN activation sequence. This behavior is attributed to the complex role played by hydrogen in the overgrown HEMT layers. The results of this study provide new insights into the development of metal organic chemical vapor deposition grown HEMTs with activated buried p-GaN films.
{"title":"Investigation of the electrical behavior of AlGaN/GaN high electron mobility transistors grown with underlying GaN:Mg layer","authors":"I. Mahaboob, S. Novak, E. Rocco, K. Hogan, F. Shahedipour-Sandvik","doi":"10.1116/6.0000255","DOIUrl":"https://doi.org/10.1116/6.0000255","url":null,"abstract":"In the current study, the electrical behavior of the AlGaN/GaN high electron mobility transistors (HEMTs) grown with an underlying GaN:Mg layer is detailed. It is shown that the activation of the buried p-GaN layer is achieved without hydrogen diffusion out of the layer. Reversal in the electrical behavior of the two-dimensional electron gas (2DEG) is also observed in the as-grown structure based on the p-GaN activation sequence. This behavior is attributed to the complex role played by hydrogen in the overgrown HEMT layers. The results of this study provide new insights into the development of metal organic chemical vapor deposition grown HEMTs with activated buried p-GaN films.","PeriodicalId":17652,"journal":{"name":"Journal of Vacuum Science & Technology. B. Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86132626","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}
Nabid Hasan, Soo-Young Lee, Byungsup Ahn, Jin Choi, Joonsoo Park
Massively parallel electron-beam systems are equipped with a large number of beams to improve the writing throughput. It is unavoidable that some of the beams are abnormal, e.g., always on or off, spatial and temporal fluctuations of beam current, beam-positioning error, etc. A practical approach to improve the writing quality is to spread the negative effects of abnormal beams spatially. The multirow writing (MRW) was introduced, which uses each beam to expose pixels over multiple rows in each writing path minimizing the localization of pixels affected by an abnormal beam. In another method, the single-row writing (SRW), each beam exposes pixels in one row in each writing path localizing the affected pixels in a row. To spread the negative effects, especially for the single-row writing, each row of pixels may be exposed through multiple passes, i.e., multipass writing. In this study, the multirow and multipass writing methods in various combinations with the MRW and SRW are compared in terms of their effectiveness in reducing the negative effects of abnormal beams. The results from an extensive simulation study are analyzed in detail.
{"title":"Effectiveness of multipass and multirow writing methods for massively parallel e-beam systems","authors":"Nabid Hasan, Soo-Young Lee, Byungsup Ahn, Jin Choi, Joonsoo Park","doi":"10.1116/6.0000547","DOIUrl":"https://doi.org/10.1116/6.0000547","url":null,"abstract":"Massively parallel electron-beam systems are equipped with a large number of beams to improve the writing throughput. It is unavoidable that some of the beams are abnormal, e.g., always on or off, spatial and temporal fluctuations of beam current, beam-positioning error, etc. A practical approach to improve the writing quality is to spread the negative effects of abnormal beams spatially. The multirow writing (MRW) was introduced, which uses each beam to expose pixels over multiple rows in each writing path minimizing the localization of pixels affected by an abnormal beam. In another method, the single-row writing (SRW), each beam exposes pixels in one row in each writing path localizing the affected pixels in a row. To spread the negative effects, especially for the single-row writing, each row of pixels may be exposed through multiple passes, i.e., multipass writing. In this study, the multirow and multipass writing methods in various combinations with the MRW and SRW are compared in terms of their effectiveness in reducing the negative effects of abnormal beams. The results from an extensive simulation study are analyzed in detail.","PeriodicalId":17652,"journal":{"name":"Journal of Vacuum Science & Technology. B. Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89194112","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}
Glenson R. Panghulan, M. Vasquez, Y. Edañol, N. Chanlek, L. Payawan
Titanium nitride/nitrogen-doped titanium oxide (TiN/N-doped TiO 2) composite films were synthesized for visible light photodegradation applications. Thin films of TiN were sputter-deposited on precleaned glass substrates in an admixture of argon and nitrogen gases. The grown TiN films were subsequently oxidized in air at 350 °C at 15, 30, and 60 min. Raman spectral analysis revealed the formation of TiO 2 with anatase structure at 15 min and transitioned to the rutile structure at longer oxidation times. X-ray photoelectron spectral analysis revealed the formation of N-doped TiO 2 from the oxidized Ti. Visible light-induced photodegradation of methylene blue as test analyte showed 30% removal efficiency after exposure to visible light after 2.5 h. The highest degradation efficiency was observed when the anatase phase of TiO 2 is the dominant phase in the film. Moreover, N-doping realized the visible light sensitivity of TiO 2. This makes the composite film ideal for solar light-driven photodegradation of organic contaminants in wastewater.
{"title":"Synthesis of TiN/N-doped TiO2 composite films as visible light active photocatalyst","authors":"Glenson R. Panghulan, M. Vasquez, Y. Edañol, N. Chanlek, L. Payawan","doi":"10.1116/6.0000304","DOIUrl":"https://doi.org/10.1116/6.0000304","url":null,"abstract":"Titanium nitride/nitrogen-doped titanium oxide (TiN/N-doped TiO 2) composite films were synthesized for visible light photodegradation applications. Thin films of TiN were sputter-deposited on precleaned glass substrates in an admixture of argon and nitrogen gases. The grown TiN films were subsequently oxidized in air at 350 °C at 15, 30, and 60 min. Raman spectral analysis revealed the formation of TiO 2 with anatase structure at 15 min and transitioned to the rutile structure at longer oxidation times. X-ray photoelectron spectral analysis revealed the formation of N-doped TiO 2 from the oxidized Ti. Visible light-induced photodegradation of methylene blue as test analyte showed 30% removal efficiency after exposure to visible light after 2.5 h. The highest degradation efficiency was observed when the anatase phase of TiO 2 is the dominant phase in the film. Moreover, N-doping realized the visible light sensitivity of TiO 2. This makes the composite film ideal for solar light-driven photodegradation of organic contaminants in wastewater.","PeriodicalId":17652,"journal":{"name":"Journal of Vacuum Science & Technology. B. Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83599541","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 energy distributions of secondary ions for the Ar ion beam sputtering of indium tin oxide were measured in dependence on geometric parameters (ion incidence angle, polar emission angle, scattering angle), ion energy, and O 2 background pressure using energy-selective mass spectrometry. The most prevalent ion species were identified to be O +, O 2 +, Ar +, In +, and Sn +. The energy distributions of O +, In +, and Sn + ions show a low-energy maximum between 10 and 20 eV, followed by a power-law decay if the scattering angle is γ > 90 °. If γ < 90 °, an additional high-energy structure evolves, which is assigned to anisotropy effects, namely, directly sputtered particles. The energy distributions of the Ar + ions show a low-energy maximum and, in dependence on the scattering angle, up to two additional high-energy structures, which are also assigned to anisotropy effects. Here it is related to direct scattering events. All additional structures show systematic correlations with scattering angle and ion energy. The energy distributions of the O 2 + ions exhibit a low-energy maximum followed by a sudden signal drop. There is almost no variation with scattering angle or ion energy. In general, increasing the O 2 background pressure results in a decrease of the particle energy due to an energy loss upon interaction with background gas particles. The experimental results are compared and discussed with calculations based on elastic two-particle collision theory and using srim, and Monte Carlo simulations using SDTrimSP.
{"title":"Energy distributions of secondary ions for the Ar ion beam sputtering of indium tin oxide","authors":"C. Bundesmann, A. Hellmich","doi":"10.1116/6.0000516","DOIUrl":"https://doi.org/10.1116/6.0000516","url":null,"abstract":"The energy distributions of secondary ions for the Ar ion beam sputtering of indium tin oxide were measured in dependence on geometric parameters (ion incidence angle, polar emission angle, scattering angle), ion energy, and O 2 background pressure using energy-selective mass spectrometry. The most prevalent ion species were identified to be O +, O 2 +, Ar +, In +, and Sn +. The energy distributions of O +, In +, and Sn + ions show a low-energy maximum between 10 and 20 eV, followed by a power-law decay if the scattering angle is γ > 90 °. If γ < 90 °, an additional high-energy structure evolves, which is assigned to anisotropy effects, namely, directly sputtered particles. The energy distributions of the Ar + ions show a low-energy maximum and, in dependence on the scattering angle, up to two additional high-energy structures, which are also assigned to anisotropy effects. Here it is related to direct scattering events. All additional structures show systematic correlations with scattering angle and ion energy. The energy distributions of the O 2 + ions exhibit a low-energy maximum followed by a sudden signal drop. There is almost no variation with scattering angle or ion energy. In general, increasing the O 2 background pressure results in a decrease of the particle energy due to an energy loss upon interaction with background gas particles. The experimental results are compared and discussed with calculations based on elastic two-particle collision theory and using srim, and Monte Carlo simulations using SDTrimSP.","PeriodicalId":17652,"journal":{"name":"Journal of Vacuum Science & Technology. B. Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89658668","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}
In the present work, a deterministic approach is applied for the first time ever to simulate the rarefied gas flow in the particle exhaust system of a nuclear fusion device. As an example of such a system, the pumping area of the DEMO (DEMOnstration Fusion Power Plant) fusion reactor is considered, which is characterized by high geometrical complexity and strong gradients of macroscopic quantities. The Knudsen number in this system may vary from free molecular up to the slip regime and the flow behavior must be described by the Boltzmann equation. In the present work, the Boltzmann equation is approximated by the well-known Bhatnagar–Gross–Krook and Shakhov kinetic models supplemented with the deterministic discrete velocity method. In addition, in order to assess the capabilities of the deterministic modeling, the problem has also been studied by solving the Boltzmann equation with the stochastic direct simulation Monte Carlo (DSMC) method. Extended comparisons between the deterministic and stochastic methods in terms of all macroscopic quantities of practical interest, namely, pressure, number density, temperature, and pumping fluxes, are performed and remarks about the effectiveness of the implemented deterministic approach have been drawn. Results are obtained by assuming He and D2 gas flows, various values of the capture coefficient at the pumping opening, and two different scenarios of the inlet gas temperature. In all examined cases, the deterministic results are in very good agreement with the DSMC ones, with the maximum relative deviation being less than 4%. The nonlinear deterministic code is significantly faster than the stochastic DSMC code for acceptable noise levels. The pumping fluxes and the pressure values in the vicinity of the pumping opening, both quantities useful for pumping system evaluation, have been calculated in terms of the capture coefficient. The present work may support decision making on the suitability of the pumping technology of DEMO and the design of the pumping system.
本文首次采用确定性方法对核聚变装置粒子排气系统中的稀薄气体流动进行了模拟。以具有几何复杂度高、宏观量梯度强等特点的DEMO (DEMOnstration Fusion Power Plant)核聚变反应堆抽运区为例。该体系的克努森数可以从自由分子到滑移状态变化，流动行为必须用玻尔兹曼方程来描述。在本工作中，玻尔兹曼方程由著名的Bhatnagar-Gross-Krook和Shakhov动力学模型和确定性离散速度方法进行近似。此外，为了评估确定性建模的能力，还利用随机直接模拟蒙特卡罗(DSMC)方法求解Boltzmann方程进行了研究。在实际意义上的所有宏观量，即压力、数量密度、温度和泵送通量方面，对确定性方法和随机方法进行了扩展比较，并对所实现的确定性方法的有效性进行了评论。通过假设He和D2气体流量、不同的抽气口俘获系数值以及两种不同的进口气体温度情景，得到了结果。在所有检测的情况下，确定性结果与DSMC的结果非常吻合，最大相对偏差小于4%。在可接受的噪声水平下，非线性确定性码明显快于随机DSMC码。用捕获系数计算了泵送通量和泵送口附近的压力值，这两个量对泵送系统的评价都是有用的。本文的工作可为DEMO抽水技术的适用性和抽水系统的设计提供决策支持。
{"title":"Deterministic and stochastic modeling of rarefied gas flows in fusion particle exhaust systems","authors":"C. Tantos, S. Varoutis, C. Day","doi":"10.1116/6.0000491","DOIUrl":"https://doi.org/10.1116/6.0000491","url":null,"abstract":"In the present work, a deterministic approach is applied for the first time ever to simulate the rarefied gas flow in the particle exhaust system of a nuclear fusion device. As an example of such a system, the pumping area of the DEMO (DEMOnstration Fusion Power Plant) fusion reactor is considered, which is characterized by high geometrical complexity and strong gradients of macroscopic quantities. The Knudsen number in this system may vary from free molecular up to the slip regime and the flow behavior must be described by the Boltzmann equation. In the present work, the Boltzmann equation is approximated by the well-known Bhatnagar–Gross–Krook and Shakhov kinetic models supplemented with the deterministic discrete velocity method. In addition, in order to assess the capabilities of the deterministic modeling, the problem has also been studied by solving the Boltzmann equation with the stochastic direct simulation Monte Carlo (DSMC) method. Extended comparisons between the deterministic and stochastic methods in terms of all macroscopic quantities of practical interest, namely, pressure, number density, temperature, and pumping fluxes, are performed and remarks about the effectiveness of the implemented deterministic approach have been drawn. Results are obtained by assuming He and D2 gas flows, various values of the capture coefficient at the pumping opening, and two different scenarios of the inlet gas temperature. In all examined cases, the deterministic results are in very good agreement with the DSMC ones, with the maximum relative deviation being less than 4%. The nonlinear deterministic code is significantly faster than the stochastic DSMC code for acceptable noise levels. The pumping fluxes and the pressure values in the vicinity of the pumping opening, both quantities useful for pumping system evaluation, have been calculated in terms of the capture coefficient. The present work may support decision making on the suitability of the pumping technology of DEMO and the design of the pumping system.","PeriodicalId":17652,"journal":{"name":"Journal of Vacuum Science & Technology. B. Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82526749","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}
Different surface preparation methods for cleaning MgO, a widely used substrate in oxide epitaxy, are summarized and compared. We find that in situ surface preparation methods are preferable to ex situ preparation methods. We show that the complete removal of hydroxide, carbonate, and adventitious carbon from the MgO surface can be achieved via oxygen plasma exposure at 200 °C without high temperature annealing. Using this process, an atomically flat surface with root mean square roughness values of ∼0.1 nm is demonstrated. Surfaces treated thus also exhibit sharp RHEED streaks indicating good crystalline order of the surface. We also show that high temperature annealing of MgO, either by itself or following other ex situ cleaning methods, such as solvent cleaning, is a reasonably effective method for the removal of surface contaminants, enabling one to achieve a surface roughness of ∼0.2 nm. We show that wet etching or other ex situ cleaning methods alone without annealing cannot eliminate all surface contaminants and may even worsen the surface roughness significantly.
{"title":"Preparation of clean MgO surface by oxygen plasma: Comparison with standard substrate cleaning procedures","authors":"J. Geler-Kremer, A. Posadas, A. Demkov","doi":"10.1116/6.0000371","DOIUrl":"https://doi.org/10.1116/6.0000371","url":null,"abstract":"Different surface preparation methods for cleaning MgO, a widely used substrate in oxide epitaxy, are summarized and compared. We find that in situ surface preparation methods are preferable to ex situ preparation methods. We show that the complete removal of hydroxide, carbonate, and adventitious carbon from the MgO surface can be achieved via oxygen plasma exposure at 200 °C without high temperature annealing. Using this process, an atomically flat surface with root mean square roughness values of ∼0.1 nm is demonstrated. Surfaces treated thus also exhibit sharp RHEED streaks indicating good crystalline order of the surface. We also show that high temperature annealing of MgO, either by itself or following other ex situ cleaning methods, such as solvent cleaning, is a reasonably effective method for the removal of surface contaminants, enabling one to achieve a surface roughness of ∼0.2 nm. We show that wet etching or other ex situ cleaning methods alone without annealing cannot eliminate all surface contaminants and may even worsen the surface roughness significantly.","PeriodicalId":17652,"journal":{"name":"Journal of Vacuum Science & Technology. B. Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90572759","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. Hirler, J. Biba, D. Lipp, H. Lochner, M. Siddabathula, S. Simon, T. Sulima, M. Wiatr, W. Hansch
Cumulative damage models are essential for reliability analysis, whether it is for the development of time-saving step-stress or ramp-stress life tests or for the qualification of products against mission-profile-based lifetime requirements. Although many cumulative damage models have been proposed in the literature, the discussion on them is rarely based on empirical data. In order to contribute to the experimental investigation of those models, three well-established models are tested for their validity. Thus, the cumulative exposure, the tampered random variable, and the tampered failure rate models are introduced in such a way that is supportive of multilevel step-stress accelerated life testing. Subsequently, experimental reliability data of semiconductor devices are used to verify or disprove the predicted failure behavior of all three models. For this purpose, university MOS-capacitors and the 22FDX® technology from GLOBALFOUNDRIES are tested. The chosen failure mechanism is the voltage and temperature accelerated time-dependent dielectric breakdown.
{"title":"Experimental reliability study of cumulative damage models on state-of-the-art semiconductor technologies for step-stress tests and mission profile stresses","authors":"A. Hirler, J. Biba, D. Lipp, H. Lochner, M. Siddabathula, S. Simon, T. Sulima, M. Wiatr, W. Hansch","doi":"10.1116/6.0000504","DOIUrl":"https://doi.org/10.1116/6.0000504","url":null,"abstract":"Cumulative damage models are essential for reliability analysis, whether it is for the development of time-saving step-stress or ramp-stress life tests or for the qualification of products against mission-profile-based lifetime requirements. Although many cumulative damage models have been proposed in the literature, the discussion on them is rarely based on empirical data. In order to contribute to the experimental investigation of those models, three well-established models are tested for their validity. Thus, the cumulative exposure, the tampered random variable, and the tampered failure rate models are introduced in such a way that is supportive of multilevel step-stress accelerated life testing. Subsequently, experimental reliability data of semiconductor devices are used to verify or disprove the predicted failure behavior of all three models. For this purpose, university MOS-capacitors and the 22FDX® technology from GLOBALFOUNDRIES are tested. The chosen failure mechanism is the voltage and temperature accelerated time-dependent dielectric breakdown.","PeriodicalId":17652,"journal":{"name":"Journal of Vacuum Science & Technology. B. Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77039974","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}
Mojtaba Amjadipour, J. Macleod, N. Motta, F. Iacopi
Heteroepitaxial thin films of cubic silicon carbide (3C-SiC) on silicon offer a promising platform for leveraging the properties of SiC, such as wide bandgap, high mechanical strength, and chemical stability on a silicon substrate. Such heteroepitaxial films also attract considerable interest as pseudosubstrates for the growth of GaN as well as graphene on silicon wafers. However, due to a substantial lattice mismatch, the growth of 3C-SiC on silicon leads to a considerable amount of stresses, defects, and diffusion phenomena at the heterointerface. We show here that the extent of such interface phenomena and stresses is so large that, after patterning of the SiC, a massive sublimation of the silicon underneath the SiC/Si interface is promoted via a high-temperature anneal, either in high or medium vacuum ambient. A micrometer-thick air gap can be formed below the SiC structures, making them suspended. Hence, the described approach can be used as a straightforward methodology to form free-standing silicon carbide structures without the need for wet or anisotropic etching and could be of great interest for devices where suspended moving parts are needed, such as micro- and nanoelectromechanical systems.
{"title":"Fabrication of free-standing silicon carbide on silicon microstructures via massive silicon sublimation","authors":"Mojtaba Amjadipour, J. Macleod, N. Motta, F. Iacopi","doi":"10.1116/6.0000490","DOIUrl":"https://doi.org/10.1116/6.0000490","url":null,"abstract":"Heteroepitaxial thin films of cubic silicon carbide (3C-SiC) on silicon offer a promising platform for leveraging the properties of SiC, such as wide bandgap, high mechanical strength, and chemical stability on a silicon substrate. Such heteroepitaxial films also attract considerable interest as pseudosubstrates for the growth of GaN as well as graphene on silicon wafers. However, due to a substantial lattice mismatch, the growth of 3C-SiC on silicon leads to a considerable amount of stresses, defects, and diffusion phenomena at the heterointerface. We show here that the extent of such interface phenomena and stresses is so large that, after patterning of the SiC, a massive sublimation of the silicon underneath the SiC/Si interface is promoted via a high-temperature anneal, either in high or medium vacuum ambient. A micrometer-thick air gap can be formed below the SiC structures, making them suspended. Hence, the described approach can be used as a straightforward methodology to form free-standing silicon carbide structures without the need for wet or anisotropic etching and could be of great interest for devices where suspended moving parts are needed, such as micro- and nanoelectromechanical systems.","PeriodicalId":17652,"journal":{"name":"Journal of Vacuum Science & Technology. B. Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78808601","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}
J. Zakrisson, I. Silander, C. Forssén, M. Zelan, O. Axner
A novel procedure for a robust assessment of cavity deformation in Fabry–Perot (FP) refractometers is presented. It is based on scrutinizing the difference between two pressures: one assessed by the uncharacterized refractometer and the other provided by an external pressure reference system, at a series of set pressures for two gases with dissimilar refractivity (here, He and N 2). By fitting linear functions to these responses and extracting their slopes, it is possible to construct two physical entities of importance: one representing the cavity deformation and the other comprising a combination of the systematic errors of a multitude of physical entities, viz., those of the assessed temperature, the assessed or estimated penetration depth of the mirror, the molar polarizabilities, and the set pressure. This provides a robust assessment of cavity deformation with small amounts of uncertainties. A thorough mathematical description of the procedure is presented that serves as a basis for the evaluation of the basic properties and features of the procedure. The analysis indicates that the cavity deformation assessments are independent of systematic errors in both the reference pressure and the assessment of gas temperature and when the gas modulation refractometry methodology is used that they are insensitive to gas leakages and outgassing into the system. It also shows that when a high-precision (sub-ppm) refractometer is characterized according to the procedure, when high purity gases are used, the uncertainty in the deformation contributes to the uncertainty in the assessment of pressure of N 2 with solely a fraction (13%) of the uncertainty of its molar polarizability, presently to a level of a few ppm. This implies, in practice, that cavity deformation is no longer a limiting factor in FP-based refractometer assessments of pressure of N 2.
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