200-mm EPL stencil mask fabrication by using SOI substrate

Shinmoto, Hiroshi; Eguchi, Hideyuki; Yoshii, Takashi; Tamura, Akira

doi:10.1117/12.504246

Cited by 5 publications

(5 citation statements)

References 10 publications

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“…Reduction of the thickness might cause breakage in the membrane during the mask fabrication process such as the deep substrate RIE for forming the membrane, the e-beam lithography and the trench RIE processed on the membrane, mask cleaning and mask handling. Our previous development had already provided a proof of the fabrication feasibility for the 2-um-thick membrane 5,8 . We fabricated EPL stencil masks with varied membrane thickness of 1.0, 1.2 and 1.5 um to assess influence of the membrane thickness on the mask fabrication feasibility.…”

Section: Fabrication Feasibility Of the Mask Having Thinner Scatterinmentioning

confidence: 99%

“…Because of the unique structure, fabrication of the EPL mask requires lots of specific processes in addition to photomask processes in general use. Despite of its peculiarities in the mask structure and the fabrication process, several vendors reported successful development of the 200-mm EPL stencil masks [4][5][6] . The EPL mask requires accurate patterns same as the other NGL masks demands.…”

Section: Introductionmentioning

confidence: 99%

“…Although applying the wafer flow process, where the e-beam writing and the dry etching are performed on a rigid SOI substrate, is able to avoid the difficult processing on the flexible membrane, image placement (IP) distortion due to removal of the silicon substrate for forming the membranes brings a critical issue 7 . We had consequently developed the membrane flow process for 200-mm EPL mask making, and succeeded in fabrication of the EPL masks with practical pattern qualities including the performance of the IP 5 .…”

Section: Introductionmentioning

confidence: 99%

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Resolution improvement of EPL stencil mask using thin membrane

et al. 2006

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Electron Projection Lithography (EPL) provides a fundamental advantage in resolution. In this paper, resolution improvement of EPL masks and minimum resolution in EPL exposure are addressed. In order to improve the mask resolution, we applied membranes thinner than typical thickness of 2 um to e-beam scattering layers of the EPL stencil masks. Although strength of the membrane generally deteriorates with decrease in the membrane thickness, the EPL masks having 1-um-thick scattering layers were feasibly fabricated. Reduction of the membrane thickness down to 1 um considerably improved the mask minimum feature size to resolve 120-nm holes and 80-nm lines which corresponded to 30 nm and 20 nm on wafer dimension, respectively, in the 4x demagnification EPL exposure system. The application of the 1-um-thick membrane simultaneously brought the high resolution and good pattern qualities: CD uniformity less than 10 nm in 3σ with pattern sidewall angle range of 90° ± 0.2°. We performed wafer exposure experiments in combination of the EPL exposure tool NSR-EB1A (Nikon) and the 1-um-thick membrane mask, and obtained the resolution performance of 40-nm holes on the wafer. We conclude that the application of the 1-um-thick membrane to the e-beam scattering layer provides high resolution EPL masks with practical CD qualities. The exposure resolution of 40-nm holes on the wafer reveals the EPL exposure system to be a potential solution for contact layers in the future technology node.

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Section: Fabrication Feasibility Of the Mask Having Thinner Scatterinmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Resolution improvement of EPL stencil mask using thin membrane

et al. 2006

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“…Fabrication of 200-mm EPL stencil masks has been reported by mask vendors. [3][4][5] Quality assurance of EPL masks is an issue for production of masks. One important quality assurance item is image placement (IP) accuracy.…”

Section: Introductionmentioning

confidence: 99%

“…Local IP errors have been measured to investigate such correlations. 4,6 Maximum local IP distortions have been estimated by simulations based on finite element methods. [8][9][10] In this paper we report the results on the local IP error measured by using a suspension type ES chuck and discuss the effect of the membrane stress and the pattern density to the local IP error.…”

Section: Introductionmentioning

confidence: 99%

200-mm EPL stencil mask fabrication and metrology at DNP: IP and CD accuracy within subfield

et al. 2004

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Electron beam projection lithography (EPL) has been developed for application to 65 nm node devices and beyond. 200-mm EPL masks have also been developed keeping pace with the exposure tool. Image placement (IP) accuracy is a necessary quality assurance item to bring masks into production. A suspension type electrostatic chuck designed for EPL mask measurement for an IP metrology tool Leica LMS IPRO was prepared for measurement of local IP errors, defined for each subfiled. The chuck holds the mask on its membrane-side surface right side up. Three 200-mm stencil masks with tensile membrane stresses of 8, 18, and 43 MPa were fabricated. The IP error is found to increase as the stress increases. Marks in the area of a high pattern density with a void fraction of 0.2 moved toward the area of a low pattern density with a void fraction of 0.016. The IP errors did not strongly depend on the kinds of dummy patterns (either hole or L&S) having the same void fraction of 0.25 and macroscopic uniformity. If the stress is less than 10 MPa, the IP error (3 sigma) is less than 10 nm, satisfying the EPL mask requirement. Local CD accuracy was also evaluated for a mask with a membrane stress of 8 MPa.

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Stress and image-placement distortions of 200mm low-energy electron projection lithography masks

Eguchi

Susa

Sumida

et al. 2004

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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Electron projection lithography mask format layer stress measurement and simulation of pattern transfer distortion J. Vac. Sci. Technol. B 20, 3053 (2002); 10.1116/1.1521732Patterning-induced image placement distortions on electron beam projection lithography membrane masks Low-energy electron projection lithography (LEEPL) is a candidate for next generation lithography and thus the 1ϫ LEEPL mask requires a stringent local image placement (IP) error budget. Applying a doping method with silicon-on-insulator substrates, 700-nm-thick membranes were investigated for stress control and in-plane distortion (IPD), which are the main contributors to local IP errors. Stress control results show that at a dopant concentration of 6.74ϫ 10 19 /cm 3 , the membrane stress in a 10 mm test structure is 8.4 MPa. Also stress variation is excellent at 0.3 MPa across a 200 mm complementary stencil mask on support strut-type LEEPL mask. The IPD results indicate that small membrane window size, low void fraction, as well as low membrane stress is the proper strategy to allow a stencil mask with dense stencil patterns to meet required IPD. Additionally, the local IP errors of large scale integrated 90 nm hole pattern were demonstrated.

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200-mm EPL stencil mask fabrication by using SOI substrate

Cited by 5 publications

References 10 publications

Resolution improvement of EPL stencil mask using thin membrane

Resolution improvement of EPL stencil mask using thin membrane

200-mm EPL stencil mask fabrication and metrology at DNP: IP and CD accuracy within subfield

Stress and image-placement distortions of 200mm low-energy electron projection lithography masks

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