Pub Date : 2019-08-19DOI: 10.1117/1.JMM.18.3.034001
Charles Valade, J. Hazart, S. Bérard-Bergery, E. Sungauer, M. Besacier, C. Gourgon
Abstract. In the microelectronics industry, most of the dimensional metrology relies on critical dimension (CD) estimation. These measurements are mainly performed by critical dimension scanning electron microscopy, because it is a very fast, mainly nondestructive method and enables direct measurements on wafers. To measure CDs, the distance is estimated between the edges of the observed pattern on an SEM image. As the CD becomes smaller and smaller, the needs for more reliable metrology techniques emerge. In order to obtain more meaningful and reproducible CD measurements regardless of the pattern type (line, space, contact, hole, etc.), one needs to perform a CD measurement at a known and constant height due to a methodology that determines the topographic shape of the pattern from SEM images. An SEM capable of bending the electron beam (up to 12 deg in our case) allows images to be caught at different angles, giving access to more information. From the analysis of such images, pattern height and sidewall angles can be determined using geometric considerations. Understanding interaction between three-dimensional (3-D) shapes, pattern materials, and the electron beam becomes essential to correlate topography information. A preliminary work based on Monte–Carlo simulations was conducted using JMONSEL, a software developed by the National Institute of Standards and Technology. With this analysis, it is possible to determine theoretical trends for different topographies and beam tilt conditions. Due to the effects highlighted by simulations, the processing of the tilted beam SEM images will be presented, as well as the method used to create a mathematical model allowing topographic reconstruction from these images. Finally some reconstruction using this model will be shown and compared to reference measurements. The overall flow used to process images is presented. First, images are transformed into grayscale profiles. After a smoothing procedure, positional descriptors are computed for specific profile derivatives values. Then, from these descriptors coming from two images of the same pattern taken at different tilt angles, we use a low-complexity linear model in order to obtain the geometrical parameters of the structure. This model is created and initially calibrated using JMONSEL simulations and then recalibrated on real silicon patterns. We demonstrate that the use of real SEM images coming from real silicon patterns with our model leads to results that are coherent with conventional 3-D measurements techniques taken as reference. Moreover, we are able to make reliable reconstructions on patterns of various heights with a single calibrated model. Our batch of experiment shows a three-sigma standard deviation of 10 nm on the estimated height for heights ranging from 50 nm to more than 200 nm. Based on simulations, we are able to reconstruct the corner rounding (CR) from SEM images. However, because our wafer has no CR variability, measurements
{"title":"Tilted beam scanning electron microscopy, 3-D metrology for microelectronics industry","authors":"Charles Valade, J. Hazart, S. Bérard-Bergery, E. Sungauer, M. Besacier, C. Gourgon","doi":"10.1117/1.JMM.18.3.034001","DOIUrl":"https://doi.org/10.1117/1.JMM.18.3.034001","url":null,"abstract":"Abstract. In the microelectronics industry, most of the dimensional metrology relies on critical dimension (CD) estimation. These measurements are mainly performed by critical dimension scanning electron microscopy, because it is a very fast, mainly nondestructive method and enables direct measurements on wafers. To measure CDs, the distance is estimated between the edges of the observed pattern on an SEM image. As the CD becomes smaller and smaller, the needs for more reliable metrology techniques emerge. In order to obtain more meaningful and reproducible CD measurements regardless of the pattern type (line, space, contact, hole, etc.), one needs to perform a CD measurement at a known and constant height due to a methodology that determines the topographic shape of the pattern from SEM images. An SEM capable of bending the electron beam (up to 12 deg in our case) allows images to be caught at different angles, giving access to more information. From the analysis of such images, pattern height and sidewall angles can be determined using geometric considerations. Understanding interaction between three-dimensional (3-D) shapes, pattern materials, and the electron beam becomes essential to correlate topography information. A preliminary work based on Monte–Carlo simulations was conducted using JMONSEL, a software developed by the National Institute of Standards and Technology. With this analysis, it is possible to determine theoretical trends for different topographies and beam tilt conditions. Due to the effects highlighted by simulations, the processing of the tilted beam SEM images will be presented, as well as the method used to create a mathematical model allowing topographic reconstruction from these images. Finally some reconstruction using this model will be shown and compared to reference measurements. The overall flow used to process images is presented. First, images are transformed into grayscale profiles. After a smoothing procedure, positional descriptors are computed for specific profile derivatives values. Then, from these descriptors coming from two images of the same pattern taken at different tilt angles, we use a low-complexity linear model in order to obtain the geometrical parameters of the structure. This model is created and initially calibrated using JMONSEL simulations and then recalibrated on real silicon patterns. We demonstrate that the use of real SEM images coming from real silicon patterns with our model leads to results that are coherent with conventional 3-D measurements techniques taken as reference. Moreover, we are able to make reliable reconstructions on patterns of various heights with a single calibrated model. Our batch of experiment shows a three-sigma standard deviation of 10 nm on the estimated height for heights ranging from 50 nm to more than 200 nm. Based on simulations, we are able to reconstruct the corner rounding (CR) from SEM images. However, because our wafer has no CR variability, measurements ","PeriodicalId":16522,"journal":{"name":"Journal of Micro/Nanolithography, MEMS, and MOEMS","volume":"7 1","pages":"034001 - 034001"},"PeriodicalIF":2.3,"publicationDate":"2019-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81939603","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 : 2019-07-25DOI: 10.1117/1.JMM.18.3.035501
Jiajing Li, Chun Zhou, Xuanxuan Chen, Paulina A. Rincon Delgadillo, P. Nealey
Abstract. Directed self-assembly (DSA) of block copolymers (BCPs) is one of the most promising techniques to tackle the ever-increasing demand for sublithographic features in semiconductor industries. BCPs with high Flory–Huggins parameter (χ) are of particular interest due to their ability to self-assemble at the length scale of sub-10 nm. However, such high-χ BCPs typically have imbalanced surface energies between respective blocks, making it a challenge to achieve desired perpendicular orientation. To address this challenge, we mixed a fluorine-containing polymeric additive with poly(2-vinylpyridine)-block-polystyrene-block-poly(2-vinylpyridine) (P2VP-b-PS-b-P2VP) and successfully controlled the orientation of the high-χ triblock copolymer. The additive selectively mixes with P2VP block through hydrogen bonding and can reduce the dissimilarity of surface energies between PS and P2VP blocks. After optimizing additive dose and annealing conditions, desired perpendicular orientation formed upon simple thermal annealing. We further demonstrated DSA of this material system with five times density multiplication and a half-pitch as small as 8.5 nm. This material system is also amenable to sequential infiltration synthesis treatment to selectively grow metal oxide in P2VP domains, which can facilitate the subsequent pattern transfer. We believe that this integration-friendly DSA platform using simple thermal annealing holds the great potential for sub-10 nm nanopatterning applications.
{"title":"Orientation control of high-χ triblock copolymer for sub-10 nm patterning using fluorine-containing polymeric additives","authors":"Jiajing Li, Chun Zhou, Xuanxuan Chen, Paulina A. Rincon Delgadillo, P. Nealey","doi":"10.1117/1.JMM.18.3.035501","DOIUrl":"https://doi.org/10.1117/1.JMM.18.3.035501","url":null,"abstract":"Abstract. Directed self-assembly (DSA) of block copolymers (BCPs) is one of the most promising techniques to tackle the ever-increasing demand for sublithographic features in semiconductor industries. BCPs with high Flory–Huggins parameter (χ) are of particular interest due to their ability to self-assemble at the length scale of sub-10 nm. However, such high-χ BCPs typically have imbalanced surface energies between respective blocks, making it a challenge to achieve desired perpendicular orientation. To address this challenge, we mixed a fluorine-containing polymeric additive with poly(2-vinylpyridine)-block-polystyrene-block-poly(2-vinylpyridine) (P2VP-b-PS-b-P2VP) and successfully controlled the orientation of the high-χ triblock copolymer. The additive selectively mixes with P2VP block through hydrogen bonding and can reduce the dissimilarity of surface energies between PS and P2VP blocks. After optimizing additive dose and annealing conditions, desired perpendicular orientation formed upon simple thermal annealing. We further demonstrated DSA of this material system with five times density multiplication and a half-pitch as small as 8.5 nm. This material system is also amenable to sequential infiltration synthesis treatment to selectively grow metal oxide in P2VP domains, which can facilitate the subsequent pattern transfer. We believe that this integration-friendly DSA platform using simple thermal annealing holds the great potential for sub-10 nm nanopatterning applications.","PeriodicalId":16522,"journal":{"name":"Journal of Micro/Nanolithography, MEMS, and MOEMS","volume":"2 1","pages":"035501 - 035501"},"PeriodicalIF":2.3,"publicationDate":"2019-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87742189","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 : 2019-07-01DOI: 10.1117/1.JMM.18.3.034005
Dong Gon Woo, Young Woong Kim, Y. Jang, S. Wi, Jinho Ahn
Abstract. Background: An extreme ultraviolet (EUV) pellicle is necessary to increase the process yield even though the declining throughput is a big concern. However, an EUV metrology/inspection tool for this pellicle has not been commercialized yet. Aim: The goal of this study is to verify the pellicle/mask inspection feasibility of EUV scanning lensless imaging (ESLI) and verify the impact of contaminants on pellicles depending on their size. Approach: Through-pellicle imaging was implemented by using ESLI, which uses a high-order harmonic generation EUV source and ptychography. Optical characteristics of various sizes of Fe-contaminated EUV pellicles were evaluated to verify their impact on wafer images. Results: Large size (∼10 μm) contaminants on the pellicle were found to contribute to the final wafer pattern loss. However, small size (2 to 3 μm) contaminants on the pellicle do not have substantial impact on the wafer image. Conclusions: The defect detection capability of ESLI for pellicle and mask was confirmed. Therefore, ESLI is useful in applications like pellicle qualification and EUV mask inspection metrology.
{"title":"Through-pellicle imaging of extreme ultraviolet mask with extreme ultraviolet ptychography microscope","authors":"Dong Gon Woo, Young Woong Kim, Y. Jang, S. Wi, Jinho Ahn","doi":"10.1117/1.JMM.18.3.034005","DOIUrl":"https://doi.org/10.1117/1.JMM.18.3.034005","url":null,"abstract":"Abstract. Background: An extreme ultraviolet (EUV) pellicle is necessary to increase the process yield even though the declining throughput is a big concern. However, an EUV metrology/inspection tool for this pellicle has not been commercialized yet. Aim: The goal of this study is to verify the pellicle/mask inspection feasibility of EUV scanning lensless imaging (ESLI) and verify the impact of contaminants on pellicles depending on their size. Approach: Through-pellicle imaging was implemented by using ESLI, which uses a high-order harmonic generation EUV source and ptychography. Optical characteristics of various sizes of Fe-contaminated EUV pellicles were evaluated to verify their impact on wafer images. Results: Large size (∼10 μm) contaminants on the pellicle were found to contribute to the final wafer pattern loss. However, small size (2 to 3 μm) contaminants on the pellicle do not have substantial impact on the wafer image. Conclusions: The defect detection capability of ESLI for pellicle and mask was confirmed. Therefore, ESLI is useful in applications like pellicle qualification and EUV mask inspection metrology.","PeriodicalId":16522,"journal":{"name":"Journal of Micro/Nanolithography, MEMS, and MOEMS","volume":"4 1","pages":"034005 - 034005"},"PeriodicalIF":2.3,"publicationDate":"2019-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87885666","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 : 2019-07-01DOI: 10.1117/1.JMM.18.3.033501
J. M. Sturm, Feng Liu, E. Darlatt, M. Kolbe, A. Aarnink, Christopher J. Lee, F. Bijkerk
Abstract. Background: The secondary electron yield (SEY) of materials is important for topics as nanoparticle photoresists and extreme ultraviolet (EUV) optics contamination. Aim: Experimentally measure SEY and secondary electron energy distributions for Ru, Sn, and Hf oxide. Approach: The SEY and energy distribution resulting from 65 to 112 eV EUV radiation are measured for thin-film oxides or films with native oxide. Results: The total SEY can be explained by EUV absorption in the topmost nanometer of (native) oxide of the investigated materials. Conclusions: Although the relative SEY of Ru and Sn is well-explained by the difference in EUV absorption properties, the SEY of HfO2 is almost a factor 2 higher than expected. Based on the energy distribution of secondary electrons, this may be related to a lower barrier for secondary electron emission.
摘要背景:材料的二次电子产率(SEY)在纳米粒子光刻胶和极紫外光(EUV)光学污染等领域具有重要意义。目的:通过实验测量Ru、Sn和Hf氧化物的SEY和二次电子能量分布。方法:测量薄膜氧化物或具有天然氧化物的薄膜在65至112 eV EUV辐射下的SEY和能量分布。结果:所研究材料的总SEY可以用(天然)氧化物最上层纳米的EUV吸收来解释。结论:虽然Ru和Sn的相对SEY可以很好地解释为EUV吸收性能的差异，但HfO2的SEY几乎比预期高2倍。根据二次电子的能量分布，这可能与较低的二次电子发射势垒有关。
{"title":"Extreme UV secondary electron yield measurements of Ru, Sn, and Hf oxide thin films","authors":"J. M. Sturm, Feng Liu, E. Darlatt, M. Kolbe, A. Aarnink, Christopher J. Lee, F. Bijkerk","doi":"10.1117/1.JMM.18.3.033501","DOIUrl":"https://doi.org/10.1117/1.JMM.18.3.033501","url":null,"abstract":"Abstract. Background: The secondary electron yield (SEY) of materials is important for topics as nanoparticle photoresists and extreme ultraviolet (EUV) optics contamination. Aim: Experimentally measure SEY and secondary electron energy distributions for Ru, Sn, and Hf oxide. Approach: The SEY and energy distribution resulting from 65 to 112 eV EUV radiation are measured for thin-film oxides or films with native oxide. Results: The total SEY can be explained by EUV absorption in the topmost nanometer of (native) oxide of the investigated materials. Conclusions: Although the relative SEY of Ru and Sn is well-explained by the difference in EUV absorption properties, the SEY of HfO2 is almost a factor 2 higher than expected. Based on the energy distribution of secondary electrons, this may be related to a lower barrier for secondary electron emission.","PeriodicalId":16522,"journal":{"name":"Journal of Micro/Nanolithography, MEMS, and MOEMS","volume":"11 1","pages":"033501 - 033501"},"PeriodicalIF":2.3,"publicationDate":"2019-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80688387","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 : 2019-06-22DOI: 10.1117/1.JMM.18.2.020101
K. Yamazoe, C. Mack
This editorial introduces a translation of a classic paper on the matrix theory of partially coherent imaging.
这篇社论介绍了一篇关于部分相干成像矩阵理论的经典论文的翻译。
{"title":"Translations in JM3","authors":"K. Yamazoe, C. Mack","doi":"10.1117/1.JMM.18.2.020101","DOIUrl":"https://doi.org/10.1117/1.JMM.18.2.020101","url":null,"abstract":"This editorial introduces a translation of a classic paper on the matrix theory of partially coherent imaging.","PeriodicalId":16522,"journal":{"name":"Journal of Micro/Nanolithography, MEMS, and MOEMS","volume":"6 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2019-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72573031","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 : 2019-06-19DOI: 10.1117/1.JMM.18.2.023505
S. Iida, T. Nagai, T. Uchiyama
Abstract. Background: Standard patterned sample with programed defects (PDs) is effective to evaluate the tool performance of pattern inspection system, but the fabrication of such standard sample, having large area dense patterns with PDs suitable for the evaluation of sub-7-nm node, is difficult. Aim: The goal of this study is to fabricate a standard sample to evaluate the performance of inspection tool for below 7-nm nodes. Approach: We use electron beam lithography with an acceleration voltage of 130 keV to fabricate standard sample. Results: We form large area dense sub-16-nm half pitch (hp) line and space (LS) patterns with PDs on 300-mm-Si-wafers, and 10- to 7-nm hp LS patterns on a 100-mm-Si wafer. Approximately 5-nm PDs with shapes including protrusions, intrusions, bridges, and openings are formed without additional defects. Moreover, pattern-etched Si wafers with 16- to 12-nm hp LS are successfully fabricated. A 100-mm-wafer with patterns is mounted into a 300-mm-Si wafer. Conclusions: The acceleration voltage of 130 keV is sufficient for the fabrication of large area dense pattern with PDs suitable for the evaluation of sub-7-nm node. Moreover, the fabricated standard wafers are useful to evaluate the tool performance of the inspection system for 300-mm wafer fabrication.
{"title":"Standard wafer with programed defects to evaluate the pattern inspection tools for 300-mm wafer fabrication for 7-nm node and beyond","authors":"S. Iida, T. Nagai, T. Uchiyama","doi":"10.1117/1.JMM.18.2.023505","DOIUrl":"https://doi.org/10.1117/1.JMM.18.2.023505","url":null,"abstract":"Abstract. Background: Standard patterned sample with programed defects (PDs) is effective to evaluate the tool performance of pattern inspection system, but the fabrication of such standard sample, having large area dense patterns with PDs suitable for the evaluation of sub-7-nm node, is difficult. Aim: The goal of this study is to fabricate a standard sample to evaluate the performance of inspection tool for below 7-nm nodes. Approach: We use electron beam lithography with an acceleration voltage of 130 keV to fabricate standard sample. Results: We form large area dense sub-16-nm half pitch (hp) line and space (LS) patterns with PDs on 300-mm-Si-wafers, and 10- to 7-nm hp LS patterns on a 100-mm-Si wafer. Approximately 5-nm PDs with shapes including protrusions, intrusions, bridges, and openings are formed without additional defects. Moreover, pattern-etched Si wafers with 16- to 12-nm hp LS are successfully fabricated. A 100-mm-wafer with patterns is mounted into a 300-mm-Si wafer. Conclusions: The acceleration voltage of 130 keV is sufficient for the fabrication of large area dense pattern with PDs suitable for the evaluation of sub-7-nm node. Moreover, the fabricated standard wafers are useful to evaluate the tool performance of the inspection system for 300-mm wafer fabrication.","PeriodicalId":16522,"journal":{"name":"Journal of Micro/Nanolithography, MEMS, and MOEMS","volume":"4 1","pages":"023505 - 023505"},"PeriodicalIF":2.3,"publicationDate":"2019-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79870159","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 : 2019-06-18DOI: 10.1117/1.JMM.18.2.021101
H. Gamo
Abstract. This is a historical translation of the seminal paper by H. Gamo, originally published in Oyo Buturi (Applied Physics, a journal of The Japan Society of Applied Physics) Vol. 25, pp. 431–443, 1956. English translation by Kenji Yamazoe, with further editing by the translator and Anthony Yen. Since optical systems have distinctive features as compared to electrical communication systems, some formulation should be prepared for the optical image in order to use it in information theory of optical systems. In this paper the following formula for the intensity distribution of the image by an optical system having a given aperture constant α in the absence of both aberration and defect in focusing is obtained by considering the nature of illumination, namely coherent, partially coherent, and incoherent: I(y)=∑n∑manmun(y)um*(y),where un(y) = sin 2πα/λ (y − nλ/2α) / 2πα/λ (y − nλ/2α) and anm = (2α/λ)2 ∬ Γ12(x1 − x2) E(x1) E* (x2) | A(x1) || A* (x2) | un(x1)um(x2)dx1 dx2. I(y) is the intensity of the image at a point of coordinate y, Γ12 the phase coherence factor introduced by H. H. Hopkins et al., E ( x ) the complex transmission coefficient of the object and A ( x ) the complex amplitude of the incident waves at the object, and the integration is taken over the object plane. The above expression has some interesting features, namely the “intensity matrix” composed of the element anm mentioned above is a positive-definite Hermitian matrix, and the diagonal elements are given by the intensities sampled at every point of the image plane separated by a distance λ / 2α, and the trace of the matrix or the sum of diagonal elements is equal to the total intensity integrated over the image plane. Since a Hermitian matrix can be reduced to diagonal form by a unitary transformation, the intensity distribution of the image can be expressed as I(y)=λ1|∑Si1ui|2+λ2|∑Si2ui|2+⋯+λn|∑Sinui|2+⋯,where λ1 , λ2 , … , λn , … are non-negative eigenvalues of the intensity matrix. In case of coherent illumination, only the first term of the above equation remains and all the other terms are zero, because the rank of the coherent intensity matrix is one, and its only non-vanishing eigenvalue is equal to the total intensity of the image. On the other hand, the rank of the incoherent intensity matrix is larger than the rank of any other coherent or partially coherent cases. The term of the largest eigenvalue in the above formulation may be especially important, because it will correspond to the coherent part of the image in case of partially coherent illumination. From the intensity matrix of the image obtained by uniform illumination of the object having uniform transmission coefficient, we may derive an interesting quantity, namely d=−∑n(λn/I0)log(λn/I0),where λn is the n-th eigenvalue of the intensity matrix and I0 is the trace of the matrix. d is zero for the coherent illumination and becomes log N for the incoherent illum
{"title":"Mathematical analysis of intensity distribution of the optical image in various degrees of coherence of illumination (representation of intensity by Hermitian matrices)","authors":"H. Gamo","doi":"10.1117/1.JMM.18.2.021101","DOIUrl":"https://doi.org/10.1117/1.JMM.18.2.021101","url":null,"abstract":"Abstract. This is a historical translation of the seminal paper by H. Gamo, originally published in Oyo Buturi (Applied Physics, a journal of The Japan Society of Applied Physics) Vol. 25, pp. 431–443, 1956. English translation by Kenji Yamazoe, with further editing by the translator and Anthony Yen. Since optical systems have distinctive features as compared to electrical communication systems, some formulation should be prepared for the optical image in order to use it in information theory of optical systems. In this paper the following formula for the intensity distribution of the image by an optical system having a given aperture constant α in the absence of both aberration and defect in focusing is obtained by considering the nature of illumination, namely coherent, partially coherent, and incoherent: I(y)=∑n∑manmun(y)um*(y),where un(y) = sin 2πα/λ (y − nλ/2α) / 2πα/λ (y − nλ/2α) and anm = (2α/λ)2 ∬ Γ12(x1 − x2) E(x1) E* (x2) | A(x1) || A* (x2) | un(x1)um(x2)dx1 dx2. I(y) is the intensity of the image at a point of coordinate y, Γ12 the phase coherence factor introduced by H. H. Hopkins et al., E ( x ) the complex transmission coefficient of the object and A ( x ) the complex amplitude of the incident waves at the object, and the integration is taken over the object plane. The above expression has some interesting features, namely the “intensity matrix” composed of the element anm mentioned above is a positive-definite Hermitian matrix, and the diagonal elements are given by the intensities sampled at every point of the image plane separated by a distance λ / 2α, and the trace of the matrix or the sum of diagonal elements is equal to the total intensity integrated over the image plane. Since a Hermitian matrix can be reduced to diagonal form by a unitary transformation, the intensity distribution of the image can be expressed as I(y)=λ1|∑Si1ui|2+λ2|∑Si2ui|2+⋯+λn|∑Sinui|2+⋯,where λ1 , λ2 , … , λn , … are non-negative eigenvalues of the intensity matrix. In case of coherent illumination, only the first term of the above equation remains and all the other terms are zero, because the rank of the coherent intensity matrix is one, and its only non-vanishing eigenvalue is equal to the total intensity of the image. On the other hand, the rank of the incoherent intensity matrix is larger than the rank of any other coherent or partially coherent cases. The term of the largest eigenvalue in the above formulation may be especially important, because it will correspond to the coherent part of the image in case of partially coherent illumination. From the intensity matrix of the image obtained by uniform illumination of the object having uniform transmission coefficient, we may derive an interesting quantity, namely d=−∑n(λn/I0)log(λn/I0),where λn is the n-th eigenvalue of the intensity matrix and I0 is the trace of the matrix. d is zero for the coherent illumination and becomes log N for the incoherent illum","PeriodicalId":16522,"journal":{"name":"Journal of Micro/Nanolithography, MEMS, and MOEMS","volume":"60 4","pages":"021101 - 021101"},"PeriodicalIF":2.3,"publicationDate":"2019-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72458231","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 : 2019-06-13DOI: 10.1117/1.JMM.18.2.021206
O. Inoue, K. Hasumi
Abstract. Overlay control has been one of the most critical issues for manufacturing of leading edge semiconductor devices. Introduction of the double patterning process requires stringent overlay control. Conventional optical overlay (Opt-OL) metrology has technical challenges with measurement robustness, solving overlay discrepancy between overlay mark and device pattern, and measuring smaller marks laid out in large numbers within the die accurately for high-order correction. In contrast, scanning electron microscope-based overlay (SEM-OL) metrology can directly measure both overlay targets and actual devices or device-like structures on processed wafers with high spatial resolution. It can be used for reference metrology and optimization of Opt-OL measurement conditions. SEM-OL uses small structures, including actual device patterns, which allows insertion of many SEM-OL targets across a die. Precise overlay distribution can be measured using dedicated SEM-OL mark, improving measurement accuracy and repeatability. To extend SEM-OL capability, we have been developing SEM-OL techniques that can measure not only surface patterns by critical dimension SEM but also buried patterns for leading edge device processes. There are two techniques to detect buried patterns. One is to use high-acceleration voltage SEM, which detects backscattering electron emphasizing material contrast. It has been adopted for overlay measurements for memory and logic devices at after-etch inspection or even after-develop inspection. The other is to utilize charging effect, which reflects voltage contrast at the surface depending on the material properties of underneath structure. SEM-OL measurement using transient voltage contrast has been developed and its capability of overlay measurement has been proven. An overlay measurement algorithm using template matching method has been developed and was applied to dynamic random access memory (DRAM) process monitor in manufacturing. In order to extend SEM-OL metrology to beyond 3-nm node logic and cutting-edge DRAM devices (half pitch = 14 nm), we are improving measurement precision of detecting buried patterns and measurement throughput by developing optimized SEM-OL mark.
{"title":"Review of scanning electron microscope-based overlay measurement beyond 3-nm node device","authors":"O. Inoue, K. Hasumi","doi":"10.1117/1.JMM.18.2.021206","DOIUrl":"https://doi.org/10.1117/1.JMM.18.2.021206","url":null,"abstract":"Abstract. Overlay control has been one of the most critical issues for manufacturing of leading edge semiconductor devices. Introduction of the double patterning process requires stringent overlay control. Conventional optical overlay (Opt-OL) metrology has technical challenges with measurement robustness, solving overlay discrepancy between overlay mark and device pattern, and measuring smaller marks laid out in large numbers within the die accurately for high-order correction. In contrast, scanning electron microscope-based overlay (SEM-OL) metrology can directly measure both overlay targets and actual devices or device-like structures on processed wafers with high spatial resolution. It can be used for reference metrology and optimization of Opt-OL measurement conditions. SEM-OL uses small structures, including actual device patterns, which allows insertion of many SEM-OL targets across a die. Precise overlay distribution can be measured using dedicated SEM-OL mark, improving measurement accuracy and repeatability. To extend SEM-OL capability, we have been developing SEM-OL techniques that can measure not only surface patterns by critical dimension SEM but also buried patterns for leading edge device processes. There are two techniques to detect buried patterns. One is to use high-acceleration voltage SEM, which detects backscattering electron emphasizing material contrast. It has been adopted for overlay measurements for memory and logic devices at after-etch inspection or even after-develop inspection. The other is to utilize charging effect, which reflects voltage contrast at the surface depending on the material properties of underneath structure. SEM-OL measurement using transient voltage contrast has been developed and its capability of overlay measurement has been proven. An overlay measurement algorithm using template matching method has been developed and was applied to dynamic random access memory (DRAM) process monitor in manufacturing. In order to extend SEM-OL metrology to beyond 3-nm node logic and cutting-edge DRAM devices (half pitch = 14 nm), we are improving measurement precision of detecting buried patterns and measurement throughput by developing optimized SEM-OL mark.","PeriodicalId":16522,"journal":{"name":"Journal of Micro/Nanolithography, MEMS, and MOEMS","volume":"50 8 1","pages":"021206 - 021206"},"PeriodicalIF":2.3,"publicationDate":"2019-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73034865","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 : 2019-06-06DOI: 10.1117/1.JMM.18.2.023504
M. Eller, Mingqi Li, Xisen Hou, S. Verkhoturov, E. Schweikert, P. Trefonas
Abstract. We describe a methodology for nanoscale molecular analysis and present its capabilities. The analysis method is based on secondary-ion mass spectrometry with gold nanoparticles (e.g., Au4004+). The methodology presented has unique features that enable nanoscale molecular analysis, namely the method of acquiring the mass spectrum and the nature of the impacting projectile. In the method, a sequence of individual gold nanoparticles (Au4004+) is used to bombard the sample; each impact results in ion emission from an area ∼10–20 nm in diameter. For each of impact of Au4004+, the emitted ions are mass analyzed by time-of-flight mass spectrometry, detected and stored together in one mass spectrum prior to the arrival of the subsequent projectile. Each mass spectrum contains elements and molecules, which are colocalized within ∼10 to 20 nm of one another. Examination of the coemitted ions allows us to test the molecular homogeneity and chemical composition at the nanoscale. We applied this method to a chemically amplified resist before and after exposure and development. After development the method was used to chemically characterize defect sites that were not removed by the developing solution.
{"title":"Nanoscale molecular analysis of photoresist films with massive cluster secondary-ion mass spectrometry","authors":"M. Eller, Mingqi Li, Xisen Hou, S. Verkhoturov, E. Schweikert, P. Trefonas","doi":"10.1117/1.JMM.18.2.023504","DOIUrl":"https://doi.org/10.1117/1.JMM.18.2.023504","url":null,"abstract":"Abstract. We describe a methodology for nanoscale molecular analysis and present its capabilities. The analysis method is based on secondary-ion mass spectrometry with gold nanoparticles (e.g., Au4004+). The methodology presented has unique features that enable nanoscale molecular analysis, namely the method of acquiring the mass spectrum and the nature of the impacting projectile. In the method, a sequence of individual gold nanoparticles (Au4004+) is used to bombard the sample; each impact results in ion emission from an area ∼10–20 nm in diameter. For each of impact of Au4004+, the emitted ions are mass analyzed by time-of-flight mass spectrometry, detected and stored together in one mass spectrum prior to the arrival of the subsequent projectile. Each mass spectrum contains elements and molecules, which are colocalized within ∼10 to 20 nm of one another. Examination of the coemitted ions allows us to test the molecular homogeneity and chemical composition at the nanoscale. We applied this method to a chemically amplified resist before and after exposure and development. After development the method was used to chemically characterize defect sites that were not removed by the developing solution.","PeriodicalId":16522,"journal":{"name":"Journal of Micro/Nanolithography, MEMS, and MOEMS","volume":"35 1","pages":"023504 - 023504"},"PeriodicalIF":2.3,"publicationDate":"2019-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74240888","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 : 2019-06-05DOI: 10.1117/1.JMM.18.2.025001
Ahmad Elshenety, E. El-Kholy, A. F. Abdou, M. Soliman, Mohsen M. Elhagry, Walaa S. Gado
Abstract. Background: Microelectromechanical systems are now one of the fastest growing engineering fields. We introduce a static gas sensor based on PolyMUMPs parallel plate actuators. The sensor exploits the pull-in phenomenon of the parallel plate actuators. The target gas is hydrogen sulfide (H2S), which is a toxic gas and popular in laboratories, factories, and petroleum industry. Aim: Reach a gas sensor in which the gas can easily be detected by a simple electronic circuit using new polymer combinations. Approach: Two concentrations of H2S (40 and 100 ppm) are used to test the ability of the sensor to capture the molecules of the gas. Gas injection process is done in a gas chamber and at ambient conditions (ambient temperature and pressure). Results: The two concentrations were successfully detected by the sensor and the electronic circuit verified the pull-in of the sensor. That was achieved using two different polymers (polypyrrole polymer and copper oxide–tin oxide/polypyrrole). Conclusions: The sensor successively detects H2S gas with 40 and 100 ppm concentrations. Verifying the pull-in of the sensor using a simple detection circuit could help in quickly moving those sensors from prototype to product.
{"title":"H2S MEMS-based gas sensor","authors":"Ahmad Elshenety, E. El-Kholy, A. F. Abdou, M. Soliman, Mohsen M. Elhagry, Walaa S. Gado","doi":"10.1117/1.JMM.18.2.025001","DOIUrl":"https://doi.org/10.1117/1.JMM.18.2.025001","url":null,"abstract":"Abstract. Background: Microelectromechanical systems are now one of the fastest growing engineering fields. We introduce a static gas sensor based on PolyMUMPs parallel plate actuators. The sensor exploits the pull-in phenomenon of the parallel plate actuators. The target gas is hydrogen sulfide (H2S), which is a toxic gas and popular in laboratories, factories, and petroleum industry. Aim: Reach a gas sensor in which the gas can easily be detected by a simple electronic circuit using new polymer combinations. Approach: Two concentrations of H2S (40 and 100 ppm) are used to test the ability of the sensor to capture the molecules of the gas. Gas injection process is done in a gas chamber and at ambient conditions (ambient temperature and pressure). Results: The two concentrations were successfully detected by the sensor and the electronic circuit verified the pull-in of the sensor. That was achieved using two different polymers (polypyrrole polymer and copper oxide–tin oxide/polypyrrole). Conclusions: The sensor successively detects H2S gas with 40 and 100 ppm concentrations. Verifying the pull-in of the sensor using a simple detection circuit could help in quickly moving those sensors from prototype to product.","PeriodicalId":16522,"journal":{"name":"Journal of Micro/Nanolithography, MEMS, and MOEMS","volume":"103 1","pages":"025001 - 025001"},"PeriodicalIF":2.3,"publicationDate":"2019-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79455993","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}
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