T. Namioka, Masaki Yamamoto, M. Yanagihara, M. Koike
Soft-x-ray (SXR) multilayers havé been successfully applied to various optical elements and systems, and their technology seems to have been nearly perfected. However, many problems fundamental to multilayers have to be solved for further development. This paper presents results of our studies on some of these problems.
{"title":"Multilayers for Soft-X-Ray Optics","authors":"T. Namioka, Masaki Yamamoto, M. Yanagihara, M. Koike","doi":"10.1364/sxray.1991.thb1","DOIUrl":"https://doi.org/10.1364/sxray.1991.thb1","url":null,"abstract":"Soft-x-ray (SXR) multilayers havé been successfully applied to various optical elements and systems, and their technology seems to have been nearly perfected. However, many problems fundamental to multilayers have to be solved for further development. This paper presents results of our studies on some of these problems.","PeriodicalId":409291,"journal":{"name":"Soft-X-Ray Projection Lithography","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131322864","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}
W. Waskiewicz, D. Windt, J. Bjorkholm, L. Eichner, R. Freeman
Spatial uniformity of the multilayer coatings deposited onto figured optics for soft x-ray projection lithography optical systems must be accurately controlled in order to maintain high throughput, and to preserve the imaging quality of the substrate. Controlling the uniformity with the desired accuracy can be quite challenging however, due to the nature of the deposition process.
{"title":"Achieving Uniform Multilayer Coatings on Figured Optics","authors":"W. Waskiewicz, D. Windt, J. Bjorkholm, L. Eichner, R. Freeman","doi":"10.1364/sxray.1991.thb3","DOIUrl":"https://doi.org/10.1364/sxray.1991.thb3","url":null,"abstract":"Spatial uniformity of the multilayer coatings deposited onto figured optics for soft x-ray projection lithography optical systems must be accurately controlled in order to maintain high throughput, and to preserve the imaging quality of the substrate. Controlling the uniformity with the desired accuracy can be quite challenging however, due to the nature of the deposition process.","PeriodicalId":409291,"journal":{"name":"Soft-X-Ray Projection Lithography","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115837404","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}
Laser-produced sources for soft x-ray projection lithography require high brightness in a narrow x-ray band in the region of high reflectivity for multilayer optics. Lasers will also probably be of only modest power matching near term laser technology development for high efficiency, high repetition rate lasers. Little experimental work has been done on characterizing x-ray emission below 300 eV at laser irradiations of a Joule or less. Experimental data will be needed over a large range of laser parameters including wavelength, intensity, and pulse width in order to assess the relative merits of any laser system proposed as a source for soft x-ray projection lithography.
{"title":"X-ray Production Efficiency at 130 Å from Laser-Produced Plasmas","authors":"R. Kauffman, D. Phillion","doi":"10.1364/sxray.1991.thc1","DOIUrl":"https://doi.org/10.1364/sxray.1991.thc1","url":null,"abstract":"Laser-produced sources for soft x-ray projection lithography require high brightness in a narrow x-ray band in the region of high reflectivity for multilayer optics. Lasers will also probably be of only modest power matching near term laser technology development for high efficiency, high repetition rate lasers. Little experimental work has been done on characterizing x-ray emission below 300 eV at laser irradiations of a Joule or less. Experimental data will be needed over a large range of laser parameters including wavelength, intensity, and pulse width in order to assess the relative merits of any laser system proposed as a source for soft x-ray projection lithography.","PeriodicalId":409291,"journal":{"name":"Soft-X-Ray Projection Lithography","volume":"157 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120849296","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}
P. Rockett, J. Hunter, R. Kensek, R. Olson, G. Kubiak
The efficiency of XUV production from a laser-plasma directly relates to the cost of fielding such a source for projection x-ray lithography (PXRL). Measurements of the radiated conversion efficiency were made on the Sandia National Laboratories Laser Plasma Source (LPS), a bright reliable point x-ray source. The LPS was designed for use as a prototype XUV source for PXRL, and included a Lambda Physik KrF laser focussed weakly onto a rotating target drum. The laser produced 1.1J pulses at 248nm in 27ns and could be operated up to 100Hz. Focal intensities on target were in the low 1010 W/cm2 using a 1m focal length simple lens.
{"title":"XUV Conversion Efficiency in a Low Intensity Krf Laser-Plasma for Projection Lithography","authors":"P. Rockett, J. Hunter, R. Kensek, R. Olson, G. Kubiak","doi":"10.1364/sxray.1991.thc3","DOIUrl":"https://doi.org/10.1364/sxray.1991.thc3","url":null,"abstract":"The efficiency of XUV production from a laser-plasma directly relates to the cost of fielding such a source for projection x-ray lithography (PXRL). Measurements of the radiated conversion efficiency were made on the Sandia National Laboratories Laser Plasma Source (LPS), a bright reliable point x-ray source. The LPS was designed for use as a prototype XUV source for PXRL, and included a Lambda Physik KrF laser focussed weakly onto a rotating target drum. The laser produced 1.1J pulses at 248nm in 27ns and could be operated up to 100Hz. Focal intensities on target were in the low 1010 W/cm2 using a 1m focal length simple lens.","PeriodicalId":409291,"journal":{"name":"Soft-X-Ray Projection Lithography","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129490654","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}
S. Davey, R. Freeman, T. J. Mcllrath, L. Vanwoerkom, W. Waskiewicz
A soft x-ray figured optic has been incorporated into a spectrometer with a multi-channel detector to enhance signal levels from short pulse laser produced plasmas.
将软x射线图形光学器件集成到具有多通道探测器的光谱仪中，以提高短脉冲激光产生的等离子体的信号水平。
{"title":"Soft X-ray Optic For An Efficient Laser Plasma Spectrometer","authors":"S. Davey, R. Freeman, T. J. Mcllrath, L. Vanwoerkom, W. Waskiewicz","doi":"10.1364/sxray.1991.wc3","DOIUrl":"https://doi.org/10.1364/sxray.1991.wc3","url":null,"abstract":"A soft x-ray figured optic has been incorporated into a spectrometer with a multi-channel detector to enhance signal levels from short pulse laser produced plasmas.","PeriodicalId":409291,"journal":{"name":"Soft-X-Ray Projection Lithography","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134445550","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}
Recent developments in x-ray laser research resulted in the experimental observation of laser amplification at many wavelengths in soft x-ray domain [1] ranging from λ=280 Å to λ = 42 Å. There is no doubts that within next few years powerful sources of coherent x-ray laser radiation at those wavelengths will also be available. This sets a stage for the research on the interaction of intense coherent x-ray radiation with a matter, in particular on x-ray nonlinear optics. The first obvious choice of the environment and frequency for the nonlinear effects to occur and to be experimentally observed, is the same plasma of ionized atoms that gives rise to the laser action itself, with the nonlinear interaction occurring at the frequency of lasing transition. The nonlinear effects in such a situation are essentially expected to be the same as in any other resonantly-enhanced nonlinear interaction of light with matter in a visible optical domain and could approximately be evaluated using basically two (or three) level model. In order to demonstrate the feasibility of this kind of nonlinear effects both in active and passive x-ray laser medium, we present here evaluations of the characteristic parameters pertinent to the resonant nonlinearity: the saturation driving intensity and nonlinear change of refractive index. We use simple and yet realistic model based on the neonlike Mo XXXIII plasma; observation of soft X-ray amplification in such a system has recently been reported [2].
{"title":"On the feasibility of X-ray nonlinear resonant effects in plasma","authors":"P. Shkolnikov, A. Kaplan","doi":"10.1364/sxray.1991.wa7","DOIUrl":"https://doi.org/10.1364/sxray.1991.wa7","url":null,"abstract":"Recent developments in x-ray laser research resulted in the experimental observation of laser amplification at many wavelengths in soft x-ray domain [1] ranging from λ=280 Å to λ = 42 Å. There is no doubts that within next few years powerful sources of coherent x-ray laser radiation at those wavelengths will also be available. This sets a stage for the research on the interaction of intense coherent x-ray radiation with a matter, in particular on x-ray nonlinear optics. The first obvious choice of the environment and frequency for the nonlinear effects to occur and to be experimentally observed, is the same plasma of ionized atoms that gives rise to the laser action itself, with the nonlinear interaction occurring at the frequency of lasing transition. The nonlinear effects in such a situation are essentially expected to be the same as in any other resonantly-enhanced nonlinear interaction of light with matter in a visible optical domain and could approximately be evaluated using basically two (or three) level model. In order to demonstrate the feasibility of this kind of nonlinear effects both in active and passive x-ray laser medium, we present here evaluations of the characteristic parameters pertinent to the resonant nonlinearity: the saturation driving intensity and nonlinear change of refractive index. We use simple and yet realistic model based on the neonlike Mo XXXIII plasma; observation of soft X-ray amplification in such a system has recently been reported [2].","PeriodicalId":409291,"journal":{"name":"Soft-X-Ray Projection Lithography","volume":"250 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123584383","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
G. Kubiak, E. Kneedler, K. Berger, R. Stulen, J. Bjorkholm
The characterization of resist materials for soft X-ray projection lithography (SXPL) in the 75-350 Å spectral region is an important issue, although it has received little attention to date. With the recent demonstration of diffraction-limited SXPL at 140 Å[1], the need to optimize resists at specific exposure wavelengths for future SXPL commercialization has become acute. Near 300 Å resist absorbance is so large that a single-layer resist strategy does not appear feasible, whereas near 80 Å it does. At intermediate wavelengths, for example where Mo/Si multilayer reflective coatings are efficient, it is not yet possible to determine whether a surface imaging or single-layer method is optimum. To estimate the maximum developed resist depth attainable at a given wavelength, the appropriate mass absorption coefficients may be used to calculate film absorbance. The accuracy of these estimates is questionable, however, especially at longer wavelengths where solid state effects can be pronounced. We have undertaken a study of single-layer resists in the spectral region relevant to SXPL and have characterized the sensitivity, contrast, and absolute absorbance of poly methylmethacrylate (PMMA), polysilane, and diazonapthoquinone/novolak resists. In addition, we have evaluated the lithographic performance of these materials at an exposure wavelength of 140 Å using an SXPL instrument illuminated by a laser plasma source (LPS) of high average power.
{"title":"Resist Characterization at Soft X-Ray Wavelengths","authors":"G. Kubiak, E. Kneedler, K. Berger, R. Stulen, J. Bjorkholm","doi":"10.1364/sxray.1991.thd3","DOIUrl":"https://doi.org/10.1364/sxray.1991.thd3","url":null,"abstract":"The characterization of resist materials for soft X-ray projection lithography (SXPL) in the 75-350 Å spectral region is an important issue, although it has received little attention to date. With the recent demonstration of diffraction-limited SXPL at 140 Å[1], the need to optimize resists at specific exposure wavelengths for future SXPL commercialization has become acute. Near 300 Å resist absorbance is so large that a single-layer resist strategy does not appear feasible, whereas near 80 Å it does. At intermediate wavelengths, for example where Mo/Si multilayer reflective coatings are efficient, it is not yet possible to determine whether a surface imaging or single-layer method is optimum. To estimate the maximum developed resist depth attainable at a given wavelength, the appropriate mass absorption coefficients may be used to calculate film absorbance. The accuracy of these estimates is questionable, however, especially at longer wavelengths where solid state effects can be pronounced. We have undertaken a study of single-layer resists in the spectral region relevant to SXPL and have characterized the sensitivity, contrast, and absolute absorbance of poly methylmethacrylate (PMMA), polysilane, and diazonapthoquinone/novolak resists. In addition, we have evaluated the lithographic performance of these materials at an exposure wavelength of 140 Å using an SXPL instrument illuminated by a laser plasma source (LPS) of high average power.","PeriodicalId":409291,"journal":{"name":"Soft-X-Ray Projection Lithography","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126252840","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}
Laser irradiation of cylindrical cavities has attracted considerable interest in the context of soft x-ray laser experiments because the confined plasma may act as an x-ray waveguide.1) Waveguiding requires a concave, radially symmetric density profile and thus uniform plasma ablation inside the cavity. In the case of transverse irradiation presented in this work, the uniformity of plasma ablation is primarily determined by the mechanisms which redistribute the energy from the initial location of plasma generation by the incident laser. Among the mechanisms to be considered are x-radiation, hot electrons, and laser light reflected at the primary spot. Experimentally, evidence was found that for short-pulse, long-wavelength, high-irradiance conditions, the redistribution of energy is dominated by reflected laser light.
{"title":"Characteristics of Sub-100-ps Laser Irradiation of Cylindrical Cavities","authors":"J. Balmer, B. Soom, U. Ellenberger, R. Weber","doi":"10.1364/sxray.1991.wa14","DOIUrl":"https://doi.org/10.1364/sxray.1991.wa14","url":null,"abstract":"Laser irradiation of cylindrical cavities has attracted considerable interest in the context of soft x-ray laser experiments because the confined plasma may act as an x-ray waveguide.1) Waveguiding requires a concave, radially symmetric density profile and thus uniform plasma ablation inside the cavity. In the case of transverse irradiation presented in this work, the uniformity of plasma ablation is primarily determined by the mechanisms which redistribute the energy from the initial location of plasma generation by the incident laser. Among the mechanisms to be considered are x-radiation, hot electrons, and laser light reflected at the primary spot. Experimentally, evidence was found that for short-pulse, long-wavelength, high-irradiance conditions, the redistribution of energy is dominated by reflected laser light.","PeriodicalId":409291,"journal":{"name":"Soft-X-Ray Projection Lithography","volume":"2012 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128160194","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}
W. Mansfield, J. Bjorkholm, A. MacDowell, R. Freeman, L. Szeto
Projection x-ray lithography has been proposed as a possible candidate for the delineation of integrated circuit features below 0.25µm (1). Recently it was demonstrated that near diffraction limited imaging could be achieved at several soft x-ray wavelengths (2) (3). Using 0.06pm thick films of PMMA, features of 0.2µm nd 0.1µm were printed at 37.5 and 14nm respectively. Figure 1 shows a scanning electron micrograph of these features. Note that the resist sidewalls exposed at 14nm are significantly more vertical than those printed at 37.5nm. The purpose of this work is to investigate the reasons for this difference by developing a simulation tool that would accurately model resist profiles in the soft x-ray regime (5 to 40nm).
{"title":"Effects of Absorption on Resist Performance in Soft X-Ray Projection Lithography","authors":"W. Mansfield, J. Bjorkholm, A. MacDowell, R. Freeman, L. Szeto","doi":"10.1364/sxray.1991.thd4","DOIUrl":"https://doi.org/10.1364/sxray.1991.thd4","url":null,"abstract":"Projection x-ray lithography has been proposed as a possible candidate for the delineation of integrated circuit features below 0.25µm (1). Recently it was demonstrated that near diffraction limited imaging could be achieved at several soft x-ray wavelengths (2) (3). Using 0.06pm thick films of PMMA, features of 0.2µm nd 0.1µm were printed at 37.5 and 14nm respectively. Figure 1 shows a scanning electron micrograph of these features. Note that the resist sidewalls exposed at 14nm are significantly more vertical than those printed at 37.5nm. The purpose of this work is to investigate the reasons for this difference by developing a simulation tool that would accurately model resist profiles in the soft x-ray regime (5 to 40nm).","PeriodicalId":409291,"journal":{"name":"Soft-X-Ray Projection Lithography","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128056312","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}
K. Murakami, Hiroshi Nakamura, T. Oshino, H. Nikaido
W/C multilayers, well known as good X-ray reflecting mirrors, were prepared by ion beam sputtering. The properties of the multilayers were investigated by low-angle X-ray diffraction, transmission electron microscopy (TEM) observation of the cross section and Auger electron spectroscopy.
{"title":"Tungsten/Carbon Multilayers Prepared By Ion Beam Sputtering","authors":"K. Murakami, Hiroshi Nakamura, T. Oshino, H. Nikaido","doi":"10.1364/sxray.1991.thb4","DOIUrl":"https://doi.org/10.1364/sxray.1991.thb4","url":null,"abstract":"W/C multilayers, well known as good X-ray reflecting mirrors, were prepared by ion beam sputtering. The properties of the multilayers were investigated by low-angle X-ray diffraction, transmission electron microscopy (TEM) observation of the cross section and Auger electron spectroscopy.","PeriodicalId":409291,"journal":{"name":"Soft-X-Ray Projection Lithography","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126988018","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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