Pub Date : 2018-12-20DOI: 10.1117/1.JMM.17.4.044004
Minoru Harada, Y. Minekawa, Fumihiko Fukunaga, K. Nakamae
Abstract. We present an overlay measurement method that is designed to use scanning electron microscope (SEM) images taken in the circuit pattern region. In the semiconductor manufacturing, the overlay is currently measured using target patterns fabricated in the scribe line region. However, there are residual errors between the measurement values in the scribe line region and the actual values in the circuit pattern region. Therefore, in-die overlay accuracy measurements using circuit patterns are required for precise overlay control. We have developed an in-die overlay accuracy measurement method based on SEM images. The overlay is directly measured by comparing a golden image and a test image captured in the circuit pattern region. Each layer is automatically recognized from the images by utilizing a “graph cut” technique, and the placement error between the two images is determined and used to calculate the overlay accuracy. This enables us to measure the overlay accuracy without specially designed target patterns or the setting up of measurement cursors. In the numerical experiments using pseudoimages, the proposed method has linearity and sensitivity for the subpixel-order overlay even if the patterns have size variations. The basic performance of this method was evaluated using real SEM images. A measurement repeatability of less than 1.35 nm (0.36 pixel) was achieved, and a reasonable wafer map of the overlay was obtained.
{"title":"In-die overlay metrology method using SEM images","authors":"Minoru Harada, Y. Minekawa, Fumihiko Fukunaga, K. Nakamae","doi":"10.1117/1.JMM.17.4.044004","DOIUrl":"https://doi.org/10.1117/1.JMM.17.4.044004","url":null,"abstract":"Abstract. We present an overlay measurement method that is designed to use scanning electron microscope (SEM) images taken in the circuit pattern region. In the semiconductor manufacturing, the overlay is currently measured using target patterns fabricated in the scribe line region. However, there are residual errors between the measurement values in the scribe line region and the actual values in the circuit pattern region. Therefore, in-die overlay accuracy measurements using circuit patterns are required for precise overlay control. We have developed an in-die overlay accuracy measurement method based on SEM images. The overlay is directly measured by comparing a golden image and a test image captured in the circuit pattern region. Each layer is automatically recognized from the images by utilizing a “graph cut” technique, and the placement error between the two images is determined and used to calculate the overlay accuracy. This enables us to measure the overlay accuracy without specially designed target patterns or the setting up of measurement cursors. In the numerical experiments using pseudoimages, the proposed method has linearity and sensitivity for the subpixel-order overlay even if the patterns have size variations. The basic performance of this method was evaluated using real SEM images. A measurement repeatability of less than 1.35 nm (0.36 pixel) was achieved, and a reasonable wafer map of the overlay was obtained.","PeriodicalId":16522,"journal":{"name":"Journal of Micro/Nanolithography, MEMS, and MOEMS","volume":"170 1","pages":"044004 - 044004"},"PeriodicalIF":2.3,"publicationDate":"2018-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84007295","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. With the continuous shrinking of critical dimension, it may require more time and effort to reduce or remove the lithography defects in the development process. Therefore, defect reduction has become one of the most important technical challenges in device mass production. With the purpose of finding an optimizing recipe, we can simulate group parameters, including nitrogen gas dispensation and wafer-rotation speed. From previous studies, we have established a model based on viscous fluid dynamics and have calculated the removing force distribution across the 300-mm-diameter wafer for the defect residual. In this model, we assumed that the defects mostly are polymer residual; once the removing force reached a certain threshold level (1 × 10 − 14 N), the defect with a “centered-ring-like” signature could be removed. For illustration, several groups of optimal parameter under postdeveloping rinse process conditions are given. The numerical simulations represent several recipes in the development process. We find that we can reproduce a group of the total force curves. From the simulation, we could find that we can get the minimally required strength from the three parameters for defect removal. We have done some experiments to validate the simulation results. The experimental data are almost in agreement with the simulation data. Therefore, the above simulation results have verified the effectiveness and validity of the proposed optimization methodology, and it also has shown that the trend of parameters provided by the optimized method has the potential to be an efficient candidate for reducing or removing lithography defects in the development process.
{"title":"Optimized parameters selected on the basis of the development defect model","authors":"Ling Ma, Buqing Xu, Qiang Wu, Lisong Dong, Taian Fan, Yuntao Jiang, Yayi Wei","doi":"10.1117/1.JMM.17.4.043508","DOIUrl":"https://doi.org/10.1117/1.JMM.17.4.043508","url":null,"abstract":"Abstract. With the continuous shrinking of critical dimension, it may require more time and effort to reduce or remove the lithography defects in the development process. Therefore, defect reduction has become one of the most important technical challenges in device mass production. With the purpose of finding an optimizing recipe, we can simulate group parameters, including nitrogen gas dispensation and wafer-rotation speed. From previous studies, we have established a model based on viscous fluid dynamics and have calculated the removing force distribution across the 300-mm-diameter wafer for the defect residual. In this model, we assumed that the defects mostly are polymer residual; once the removing force reached a certain threshold level (1 × 10 − 14 N), the defect with a “centered-ring-like” signature could be removed. For illustration, several groups of optimal parameter under postdeveloping rinse process conditions are given. The numerical simulations represent several recipes in the development process. We find that we can reproduce a group of the total force curves. From the simulation, we could find that we can get the minimally required strength from the three parameters for defect removal. We have done some experiments to validate the simulation results. The experimental data are almost in agreement with the simulation data. Therefore, the above simulation results have verified the effectiveness and validity of the proposed optimization methodology, and it also has shown that the trend of parameters provided by the optimized method has the potential to be an efficient candidate for reducing or removing lithography defects in the development process.","PeriodicalId":16522,"journal":{"name":"Journal of Micro/Nanolithography, MEMS, and MOEMS","volume":"56 1","pages":"043508 - 043508"},"PeriodicalIF":2.3,"publicationDate":"2018-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86276300","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-12-19DOI: 10.1117/1.JMM.17.4.043507
Miles Wilklow-Marnell, D. Moglia, B. Steimle, B. Cardineau, H. Al-Mashat, Peter Nastasi, K. Heard, Amber Aslam, Rachel Kaminski, M. Murphy, Ryan Del Re, M. Sortland, M. Vockenhuber, Y. Ekinci, R. Brainard, D. Freedman
Abstract. We have developed inorganic oxalate compounds [PPh3(CH2Ph)][M(2,2′-bipyridine)n(oxalate)(3-n)] (n=1, 2, 3; M = Co, Fe, Cr) capable of acting as negative-tone extreme ultraviolet (EUV) resists. Two important trends are observed: (1) sensitivity increases with the number of oxalate ligands; (2) Cobalt and iron complexes exhibit greater sensitivity than analogous chromium complexes. Lithographic studies of the most successful compound, [PPh3(CH2Ph)][Co(2,2′-bipyridine)(oxalate)2], show that it can consistently achieve 20 nm h/p lines at doses approaching 30 mJ/cm2. Infrared, paramagnetic nuclear magnetic resonance, and cyclic voltammetric studies of this compound show that the reaction products of the EUV photochemistry are Co(II)(2,2′-bipyridine)(oxalate) and [PPh3(CH2Ph)]2(oxalate) formed from the decomposition of one of the oxalate ligands into two equivalents each of carbon dioxide and electrons.
{"title":"First-row transitional-metal oxalate resists for EUV","authors":"Miles Wilklow-Marnell, D. Moglia, B. Steimle, B. Cardineau, H. Al-Mashat, Peter Nastasi, K. Heard, Amber Aslam, Rachel Kaminski, M. Murphy, Ryan Del Re, M. Sortland, M. Vockenhuber, Y. Ekinci, R. Brainard, D. Freedman","doi":"10.1117/1.JMM.17.4.043507","DOIUrl":"https://doi.org/10.1117/1.JMM.17.4.043507","url":null,"abstract":"Abstract. We have developed inorganic oxalate compounds [PPh3(CH2Ph)][M(2,2′-bipyridine)n(oxalate)(3-n)] (n=1, 2, 3; M = Co, Fe, Cr) capable of acting as negative-tone extreme ultraviolet (EUV) resists. Two important trends are observed: (1) sensitivity increases with the number of oxalate ligands; (2) Cobalt and iron complexes exhibit greater sensitivity than analogous chromium complexes. Lithographic studies of the most successful compound, [PPh3(CH2Ph)][Co(2,2′-bipyridine)(oxalate)2], show that it can consistently achieve 20 nm h/p lines at doses approaching 30 mJ/cm2. Infrared, paramagnetic nuclear magnetic resonance, and cyclic voltammetric studies of this compound show that the reaction products of the EUV photochemistry are Co(II)(2,2′-bipyridine)(oxalate) and [PPh3(CH2Ph)]2(oxalate) formed from the decomposition of one of the oxalate ligands into two equivalents each of carbon dioxide and electrons.","PeriodicalId":16522,"journal":{"name":"Journal of Micro/Nanolithography, MEMS, and MOEMS","volume":"7 1","pages":"043507 - 043507"},"PeriodicalIF":2.3,"publicationDate":"2018-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86443311","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-12-14DOI: 10.1117/1.JMM.17.4.045001
Khushbu Mehta, D. Bansal, Anuroop Bajpai, Ashudeep Minhas, Amit Kumar, M. Kaur, Prem Kumar, K. Rangra
Abstract. The presence of dielectric charging in a switch causes stiction and drift in pull-in voltage. A design to alleviate charging issues for RF MEMS switches is proposed. An RF MEMS capacitive switch has been fabricated and characterized. Measured pull-in of the switch is <20 V and pull-up voltage is 17 V with a switching time of 78 μs. Insertion loss and isolation of the switch are measured by varying RF power from 0 to 15 dBm at room temperature. Insertion loss and isolation of the switch are better than 0.1 and 17 dB, respectively. Resonant frequency of the device is 8.4 kHz. The switch has completed 600 million cycles.
{"title":"Reduced dielectric charging RF MEMS capacitive switch","authors":"Khushbu Mehta, D. Bansal, Anuroop Bajpai, Ashudeep Minhas, Amit Kumar, M. Kaur, Prem Kumar, K. Rangra","doi":"10.1117/1.JMM.17.4.045001","DOIUrl":"https://doi.org/10.1117/1.JMM.17.4.045001","url":null,"abstract":"Abstract. The presence of dielectric charging in a switch causes stiction and drift in pull-in voltage. A design to alleviate charging issues for RF MEMS switches is proposed. An RF MEMS capacitive switch has been fabricated and characterized. Measured pull-in of the switch is <20 V and pull-up voltage is 17 V with a switching time of 78 μs. Insertion loss and isolation of the switch are measured by varying RF power from 0 to 15 dBm at room temperature. Insertion loss and isolation of the switch are better than 0.1 and 17 dB, respectively. Resonant frequency of the device is 8.4 kHz. The switch has completed 600 million cycles.","PeriodicalId":16522,"journal":{"name":"Journal of Micro/Nanolithography, MEMS, and MOEMS","volume":"13 1","pages":"045001 - 045001"},"PeriodicalIF":2.3,"publicationDate":"2018-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89645548","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-12-12DOI: 10.1117/1.JMM.17.4.043506
Y. Vesters, Jing Jiang, Hiroki Yamamoto, D. De Simone, T. Kozawa, S. De Gendt, G. Vandenberghe
Abstract. Extreme ultraviolet (EUV) lithography utilizes photons with 92 eV energy to ionize resists, generate secondary electrons, and enable electron driven reactions that produce acid in chemically amplified photoresists. Efficiently using the available photons is of key importance. To increase photon absorption, sensitizer molecules, containing highly absorbing elements, can be added to photoresist formulations. These sensitizers have gained growing attention in recent years, showing significant sensitivity improvement. Aside from an increasing absorption, adding metal salts into the resist formulation can induce other mechanisms, like higher secondary electron generation or acid yield, or modification of the dissolution rate that also can affect patterning performance. In this work, we used different sensitizers in chemically amplified resists. We measured experimentally the absorption of EUV light, the acid yield, the photoelectron emission, the dissolution rate, and the patterning performance of the resists. Addition of a sensitizer raised the acid yield even though a decrease in film absorbance occurred, suggesting an apparent increase in chemically resonant secondary electrons. While patterning results confirm a significant sensitivity improvement, it was at the cost of roughness degradation at higher sensitizer loading. This is hypothesized by the chemical distribution of the sensitizer in the resist combined with a modification of the dissolution contrast, as observed by dissolution rate monitor measurements.
{"title":"Sensitizers in extreme ultraviolet chemically amplified resists: mechanism of sensitivity improvement","authors":"Y. Vesters, Jing Jiang, Hiroki Yamamoto, D. De Simone, T. Kozawa, S. De Gendt, G. Vandenberghe","doi":"10.1117/1.JMM.17.4.043506","DOIUrl":"https://doi.org/10.1117/1.JMM.17.4.043506","url":null,"abstract":"Abstract. Extreme ultraviolet (EUV) lithography utilizes photons with 92 eV energy to ionize resists, generate secondary electrons, and enable electron driven reactions that produce acid in chemically amplified photoresists. Efficiently using the available photons is of key importance. To increase photon absorption, sensitizer molecules, containing highly absorbing elements, can be added to photoresist formulations. These sensitizers have gained growing attention in recent years, showing significant sensitivity improvement. Aside from an increasing absorption, adding metal salts into the resist formulation can induce other mechanisms, like higher secondary electron generation or acid yield, or modification of the dissolution rate that also can affect patterning performance. In this work, we used different sensitizers in chemically amplified resists. We measured experimentally the absorption of EUV light, the acid yield, the photoelectron emission, the dissolution rate, and the patterning performance of the resists. Addition of a sensitizer raised the acid yield even though a decrease in film absorbance occurred, suggesting an apparent increase in chemically resonant secondary electrons. While patterning results confirm a significant sensitivity improvement, it was at the cost of roughness degradation at higher sensitizer loading. This is hypothesized by the chemical distribution of the sensitizer in the resist combined with a modification of the dissolution contrast, as observed by dissolution rate monitor measurements.","PeriodicalId":16522,"journal":{"name":"Journal of Micro/Nanolithography, MEMS, and MOEMS","volume":"20 1","pages":"043506 - 043506"},"PeriodicalIF":2.3,"publicationDate":"2018-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82153221","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-12-08DOI: 10.1117/1.JMM.18.1.011007
Hong Xu, V. Kosma, K. Sakai, E. Giannelis, C. Ober
Abstract. With the rapid development of semiconductors, today’s optical lithography is approaching its physical limits, and thus alternative patterning technology is urgently needed. Extreme ultraviolet (EUV) lithography, using a wavelength of 13.5 nm, is considered one of the most prominent candidates for next-generation lithography. The main challenge for EUV resists is to simultaneously satisfy resolution, line-width roughness, and sensitivity requirements following the ITRS roadmap. Though polymer-based chemically amplified resist is the current standard photoresist, entirely new resist platforms are required due to the performance targets of future process nodes. Our recent progress in metal oxide nanoparticle photoresist research will be discussed with a focus on zirconium and hafnium oxides. A brief discussion of a number of important structural and material properties pertaining to key characteristics affecting resist performance is also included.
{"title":"EUV photolithography: resist progress in metal–organic complex photoresists","authors":"Hong Xu, V. Kosma, K. Sakai, E. Giannelis, C. Ober","doi":"10.1117/1.JMM.18.1.011007","DOIUrl":"https://doi.org/10.1117/1.JMM.18.1.011007","url":null,"abstract":"Abstract. With the rapid development of semiconductors, today’s optical lithography is approaching its physical limits, and thus alternative patterning technology is urgently needed. Extreme ultraviolet (EUV) lithography, using a wavelength of 13.5 nm, is considered one of the most prominent candidates for next-generation lithography. The main challenge for EUV resists is to simultaneously satisfy resolution, line-width roughness, and sensitivity requirements following the ITRS roadmap. Though polymer-based chemically amplified resist is the current standard photoresist, entirely new resist platforms are required due to the performance targets of future process nodes. Our recent progress in metal oxide nanoparticle photoresist research will be discussed with a focus on zirconium and hafnium oxides. A brief discussion of a number of important structural and material properties pertaining to key characteristics affecting resist performance is also included.","PeriodicalId":16522,"journal":{"name":"Journal of Micro/Nanolithography, MEMS, and MOEMS","volume":"52 1","pages":"011007 - 011007"},"PeriodicalIF":2.3,"publicationDate":"2018-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80874938","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. Background: Defect compensation is one of the enabling techniques for high-volume manufacturing using extreme ultraviolet lithography. Aim: The advanced evolution strategy algorithm based on covariance matrix adaption is applied to compensation optimization to improve the convergence efficiency and algorithm operability. Approach: The advanced algorithm optimizes the solution population by sampling from the self-adapted covariance matrix of mutation distribution. Results: Optimization simulations for three different masks validated the algorithm’s advantage in convergence efficiency and searching ability compared with original differential evolution, evolution strategy, genetic algorithm (GA), and Nelder–Mead simplex method. The advanced algorithm employs fewer user-defined parameters and is proved to be robust to variations of these parameters. Conclusions: The advanced algorithm obtains better results compared with GA for best-focus, through-focus, and complex-pattern optimizations. With the inherent invariance property, appropriate operability, and robustness, we recommend applying this algorithm to other lithography optimization problems.
{"title":"Optimization of defect compensation for extreme ultraviolet lithography mask by covariance-matrix-adaption evolution strategy","authors":"Heng Zhang, Sikun Li, Xiangzhao Wang, Chaoxing Yang, Wei Cheng","doi":"10.1117/1.JMM.17.4.043505","DOIUrl":"https://doi.org/10.1117/1.JMM.17.4.043505","url":null,"abstract":"Abstract. Background: Defect compensation is one of the enabling techniques for high-volume manufacturing using extreme ultraviolet lithography. Aim: The advanced evolution strategy algorithm based on covariance matrix adaption is applied to compensation optimization to improve the convergence efficiency and algorithm operability. Approach: The advanced algorithm optimizes the solution population by sampling from the self-adapted covariance matrix of mutation distribution. Results: Optimization simulations for three different masks validated the algorithm’s advantage in convergence efficiency and searching ability compared with original differential evolution, evolution strategy, genetic algorithm (GA), and Nelder–Mead simplex method. The advanced algorithm employs fewer user-defined parameters and is proved to be robust to variations of these parameters. Conclusions: The advanced algorithm obtains better results compared with GA for best-focus, through-focus, and complex-pattern optimizations. With the inherent invariance property, appropriate operability, and robustness, we recommend applying this algorithm to other lithography optimization problems.","PeriodicalId":16522,"journal":{"name":"Journal of Micro/Nanolithography, MEMS, and MOEMS","volume":"1 1","pages":"043505 - 043505"},"PeriodicalIF":2.3,"publicationDate":"2018-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85085669","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-12-01DOI: 10.1117/1.JMM.17.4.044003
Longfei Zhang, Xingrui Wang, Xinbin Cheng, Xiao Deng
Abstract. Background: The multilayer gratings are considered as the potential length-standard-traceable lateral scales for calibrating the next-generation critical dimension scanning electron microscope (CD-SEM) magnification. As a key step in the fabrication of multilayer gratings, selective wet etching determines the final grating structure formation. However, the effects of the etching process parameters on the multilayer gratings in several nanometer scales have not been reported in detail. Aim: By optimizing the process of selective wet etching, we should fabricate high-aspect-ratio and uniform multilayer gratings to obtain high-contrast secondary electron signals and stable secondary electron images while also obtaining measurement accuracy from the small line edge roughness. Approach: Based on the analysis of the important factors in the etching process and SEM and TEM measurement results, we evaluate the effects of ultrasonic agitation, HF acid concentration, etch time, and linewidth scale on the aspect-ratio and uniform of multilayer gratings. Results: We recommend to etching the multilayer films with an HF acid concentration of about 2% during the ultrasonic agitation for uniformity. Moreover, selective wet etching reaction is limited by scale when the linewidth is below 20 nm. Despite the fact that the grating structure is fragile and easy to be broken down, for linewidths of about 10 and 5 nm, the aspect ratio of multilayer gratings can reach about 3 and 2, respectively. Conclusions: By focusing on the optimum conditions of ultrasonic agitation, HF acid concentration, and linewidth scale in the selective wet etching, selective wet etching can be used to fabricate high-aspect-ratio and uniform multilayer gratings with linewidth below 20 nm.
{"title":"Process optimization of selective wet etching for fabrication of high-aspect-ratio and uniform multilayer grating reference materials","authors":"Longfei Zhang, Xingrui Wang, Xinbin Cheng, Xiao Deng","doi":"10.1117/1.JMM.17.4.044003","DOIUrl":"https://doi.org/10.1117/1.JMM.17.4.044003","url":null,"abstract":"Abstract. Background: The multilayer gratings are considered as the potential length-standard-traceable lateral scales for calibrating the next-generation critical dimension scanning electron microscope (CD-SEM) magnification. As a key step in the fabrication of multilayer gratings, selective wet etching determines the final grating structure formation. However, the effects of the etching process parameters on the multilayer gratings in several nanometer scales have not been reported in detail. Aim: By optimizing the process of selective wet etching, we should fabricate high-aspect-ratio and uniform multilayer gratings to obtain high-contrast secondary electron signals and stable secondary electron images while also obtaining measurement accuracy from the small line edge roughness. Approach: Based on the analysis of the important factors in the etching process and SEM and TEM measurement results, we evaluate the effects of ultrasonic agitation, HF acid concentration, etch time, and linewidth scale on the aspect-ratio and uniform of multilayer gratings. Results: We recommend to etching the multilayer films with an HF acid concentration of about 2% during the ultrasonic agitation for uniformity. Moreover, selective wet etching reaction is limited by scale when the linewidth is below 20 nm. Despite the fact that the grating structure is fragile and easy to be broken down, for linewidths of about 10 and 5 nm, the aspect ratio of multilayer gratings can reach about 3 and 2, respectively. Conclusions: By focusing on the optimum conditions of ultrasonic agitation, HF acid concentration, and linewidth scale in the selective wet etching, selective wet etching can be used to fabricate high-aspect-ratio and uniform multilayer gratings with linewidth below 20 nm.","PeriodicalId":16522,"journal":{"name":"Journal of Micro/Nanolithography, MEMS, and MOEMS","volume":"70 1","pages":"044003 - 044003"},"PeriodicalIF":2.3,"publicationDate":"2018-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86307817","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-12-01DOI: 10.1117/1.JMM.17.1.013503
L. Mattii, D. Milojevic, P. Debacker, Mladen Berekovic, S. M. Y. Sherazi, B. Chava, M. Bardon, P. Schuddinck, D. Rodopoulos, R. Baert, V. Gerousis, J. Ryckaert, P. Raghavan
Abstract. Standard-cell design, technology choices, and place and route (P&R) efficiency are deeply interrelated in CMOS technology nodes below 10 nm, where lower number of tracks cells and higher pin densities pose increasingly challenging problems to the router in terms of congestion and pin accessibility. To evaluate and downselect the best solutions, a holistic design-technology co-optimization approach leveraging state-of-the-art P&R tools is thus necessary. We adopt such an approach using the imec N7 technology platform, with contacted poly pitch of 42 nm and tightest metal pitch of 32 nm, by comparing post P&R area of an IP block for different standard cell configurations, technology options, and cell height. Keeping the technology node and the set of ground rules unchanged, we demonstrate that a careful combination of these solutions can enable area gains of up to 50%, comparable with the area benefits of migrating to another node. We further demonstrate that these area benefits can be achieved at isoperformance with >20% reduced power. As at the end of the CMOS roadmap, conventional scaling enacted through pitch reduction is made more and more challenging by constraints imposed by lithography limits, material resistivity, manufacturability, and ultimately wafer cost, the approach shown herein offers a valid, attractive, and low-cost alternative.
{"title":"Post place and route design-technology co-optimization for scaling at single-digit nodes with constant ground rules","authors":"L. Mattii, D. Milojevic, P. Debacker, Mladen Berekovic, S. M. Y. Sherazi, B. Chava, M. Bardon, P. Schuddinck, D. Rodopoulos, R. Baert, V. Gerousis, J. Ryckaert, P. Raghavan","doi":"10.1117/1.JMM.17.1.013503","DOIUrl":"https://doi.org/10.1117/1.JMM.17.1.013503","url":null,"abstract":"Abstract. Standard-cell design, technology choices, and place and route (P&R) efficiency are deeply interrelated in CMOS technology nodes below 10 nm, where lower number of tracks cells and higher pin densities pose increasingly challenging problems to the router in terms of congestion and pin accessibility. To evaluate and downselect the best solutions, a holistic design-technology co-optimization approach leveraging state-of-the-art P&R tools is thus necessary. We adopt such an approach using the imec N7 technology platform, with contacted poly pitch of 42 nm and tightest metal pitch of 32 nm, by comparing post P&R area of an IP block for different standard cell configurations, technology options, and cell height. Keeping the technology node and the set of ground rules unchanged, we demonstrate that a careful combination of these solutions can enable area gains of up to 50%, comparable with the area benefits of migrating to another node. We further demonstrate that these area benefits can be achieved at isoperformance with >20% reduced power. As at the end of the CMOS roadmap, conventional scaling enacted through pitch reduction is made more and more challenging by constraints imposed by lithography limits, material resistivity, manufacturability, and ultimately wafer cost, the approach shown herein offers a valid, attractive, and low-cost alternative.","PeriodicalId":16522,"journal":{"name":"Journal of Micro/Nanolithography, MEMS, and MOEMS","volume":"20 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2018-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73329151","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-11-27DOI: 10.1117/1.JMM.17.4.043504
M. Timmermans, Marina Mariano, I. Pollentier, O. Richard, C. Huyghebaert, E. Gallagher
Abstract. To enable high volume manufacturing with extreme ultraviolet (EUV) lithography, a pellicle membrane is needed to protect the reticle from particles at EUV source powers beyond 250 W. Identifying a membrane with high EUV transmission, mechanical integrity, thermal stability, and chemical resistance to the scanner environment is extremely challenging; yet, these properties are required to realize next-generation EUV pellicle solutions. Free-standing carbon nanotube (CNT) film as an alternative next-generation core pellicle material is proposed. We demonstrate that free-standing CNT films possess very high EUV transmission (up to 99%) and good transmission uniformity (∼0.4 % half range), mechanical stability (maximum deflection ∼0.08 mm at 2 Pa), thermal stability (no transmission change under greater than 250 W equivalent EUV power in vacuum), and scalability to a full pellicle size (∼15 × 12 cm2). The capability of the CNT membrane to withstand high EUV power in the presence of H2 for a limited time is demonstrated. Other CNT membrane properties are presented that are important for the pellicle application: low EUV scattering, low EUV reflectivity, and sufficient transmission to enable through-pellicle inspection with DUV light or electrons. The ability of the CNT film to stop particles is tested. The influence of hydrogen at higher EUV powers and prolonged exposures on the lifetime of the CNT pellicle remains the current research focus. Approaches for coating the free-standing CNT films for protection are discussed.
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