Actinic mask metrology for extreme ultraviolet lithography

Kinoshita, Hiroo; Haga, Tsuneyuki; Hamamoto, Kazuhiro; Takada, Shintaro; Kazui, N.; Kakunai, Satoshi; Tsubakino, Harushige; Shoki, Tsutomu; Endo, M.; Watanabe, Takeo

doi:10.1116/1.1643057

Cited by 34 publications

(21 citation statements)

References 10 publications

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“…Thus, we have constructed an EUV microscope for aerial image mask inspection. [10][11][12] Figure 2 shows the configuration of the actinic EUV microscope installed at the BL-3 beamline in the New-SUBARU synchrotron radiation (SR) facility. 13) It consists of Schwarzschild optics, a Mirau interferometer for phaseshift interference measurement, an X-Y sample stage, a focus detector, an X-ray zooming tube connected to a CCD camera, and an image processing computer.…”

Section: Introductionmentioning

confidence: 99%

Aerial Image Mask Inspection System for Extreme Ultraviolet Lithography

Kinoshita

Hamamoto

Sakaya

et al. 2007

jjap

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We constructed an extreme ultraviolet microscopy (EUVM) system for actinic mask inspection that consists of Schwarzschild optics and an X-ray zooming tube. Using this system, a finished extreme ultraviolet lithography (EUVL) mask and Mo/Si glass substrates were inspected. An EUVM image of a 100-nm-width pattern on a 6025 glass mask was clealy observed. The resolution was estimated to be 50 nm or less from this pattern. The programmed phase defect on the glass substrate was also used for inspection. By using the EUV microscope, a programmed phase defect with widths of 90, 100, and 110 nm, a bump of 5 nm and a length of 400 mm was observed finely. The programmed phase defect of a 100-nm-wide and 2-nm-deep pit was also observed. Thus, in this research, the observation of a programmed phase defect was advanced using the EUV microscope, which succeeded in observing a topological defect structure image of a multilayer film. These results show that it is possible to detect the internal reflectance distribution of a multilayer film under the EUV microscope, without depending on surface pertubation.

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Section: Introductionmentioning

confidence: 99%

Aerial Image Mask Inspection System for Extreme Ultraviolet Lithography

Kinoshita

Hamamoto

Sakaya

et al. 2007

jjap

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“…To detect critical phase defects on an EUVL mask blank, several kinds of actinic and non-actinic inspection techniques were developed and evaluated for their inspection capabilities. [1][2][3][4][5] Besides development of techniques for inspecting multilayer-coated mask blank, understanding the impacts of phase defects on the printed pattern with varying sizes was also considered important in order to understand the critical defects. In the MIRAI-Selete's work, a technique for actinic inspection of EUVL mask blank utilizing dark-field imaging was developed with a 99% probability of detecting 1.2 nm-high and 40 nm-wide phase defect.…”

Section: Introductionmentioning

confidence: 99%

Phase defect printability analyses: dependence of defect type and EUV exposure condition

Terasawa¹,

Yamane²,

Arisawa³

et al. 2012

SPIE Proceedings

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Phase defect printability and imaging characteristics were investigated by using aerial image simulation to clarify the phase defect impact on patterns depending on defect types, and on exposure conditions. In particular, the difference between the impacts caused by the same size bump phase defect and pit phase defect on 28 nm ~ 16 nm L&S projected patterns were investigated by calculating line width variations. Aerial images of phase defects in an absence of any absorber pattern were also calculated, and the image intensity losses of the two types of defects were compared. For a dipole illumination with 0.25 NA (numerical aperture) the pit phase defect impact was found to be stronger than the bump phase defect impact, when the two defect widths were less than 70% of the half-pitch of L&S patterns on the mask. This occurrence was not foreseen by the defect image calculation. On the other hand, for circular illumination with 0.33 NA, the bump defect impact was found to be stronger than the pit phase defect impact, which was consistent with the defect image calculation results. The contribution of dipole illumination in lowering the phase defect impact was confirmed for both bump and pit phase defects.

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“…An actinic (at-wavelength) inspection can provide phase defect detection capability for which various inspection techniques have been investigated. [6][7][8][9][10][11] We have been working on the development of actinic dark-field inspection of EUVL mask blank based on an original proposal by National Institute of Advanced Industrial and Science Technologies (AIST), 12,13) where those studies were conducted at MIRAI-II. [14][15][16][17][18] In our previous work, an actinic inspection with dark field imaging was experimentally demonstrated to have a capability of detecting multilayer phase defect caused by a particle defect with a small height down to 2 nm.…”

Section: Introductionmentioning

confidence: 99%

Actinic Mask Blank Inspection and Signal Analysis for Detecting Phase Defects Down to 1.5 nm in Height

Terasawa¹,

Yamane²,

Tanaka³

et al. 2009

jjap

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The capability of an actinic (at-wavelength) inspection system for extreme ultraviolet lithography (EUVL) mask blank has been analyzed by experiment and simulation. The actinic inspection optics, that we developed to obtain a two-dimensional dark field image, consists of illumination optics, Schwarzschild optics with concave and convex mirrors as dark-field imaging optics, and a back-illuminated chargecoupled-device (BI-CCD). A test mask blank with programmed bump defects of smaller sizes and lower heights compared to those used in a previous work was fabricated and the bump defects were detected by the tool. The inspection experiments demonstrated that fabricated multilayer defects down to 1.5 nm in top height and 60 nm in width can be successfully detected. The simulation further indicated that the inspection optics performed well in detecting phase defects of 1.5 nm in height and 40 nm in width.

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Actinic mask metrology for extreme ultraviolet lithography

Cited by 34 publications

References 10 publications

Aerial Image Mask Inspection System for Extreme Ultraviolet Lithography

Aerial Image Mask Inspection System for Extreme Ultraviolet Lithography

Phase defect printability analyses: dependence of defect type and EUV exposure condition

Actinic Mask Blank Inspection and Signal Analysis for Detecting Phase Defects Down to 1.5 nm in Height

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