Maskless, microlens EUV lithography system
First Claim
1. A printing exposure apparatus comprising a radiation source, an illumination system, a modulator mechanism, a printhead, and a scanning mechanism, whereinthe printhead comprises a printhead aperture and an array of printer pixels distributed across the printhead aperture, each pixel comprises a sequence of corresponding microlenses, which are symbolically designated as L1, L2, . . . , LN, wherein N is an integer greater than 1, the illumination system conveys radiation from the radiation source to the printhead, whereupon the first microlens L1 in each sequence receives illuminating radiation, each microlens Lm other than the last microlens LN in the sequence focuses the illuminating radiation onto the next corresponding microlens Lm+1, the last microlens LN in each sequence focuses the illuminating radiation onto a corresponding focal point on a printing surface, the modulator mechanism modulates the radiation, whereby the focal points'"'"' exposure intensity levels are controllably varied, the modulator mechanism is a spatial light modulator comprising an array of modulator elements, each pixel further comprises one such modulator element disposed between that pixel'"'"'s microlens L1 and the printing surface, the exposure intensity at each pixel'"'"'s corresponding focal point is modulated independently of other pixels, and the scanning mechanism establishes relative motion between the printing surface and the printhead in synchronization with the modulator mechanism as the printing surface is exposed, whereby a synthesized, high-resolution exposure image is formed on the printing surface.
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Abstract
A maskless, extreme ultraviolet (EUV) lithography system uses microlens arrays to focus EUV radiation (at an operating wavelength of 11.3 nm) onto diffraction-limited (58-nm FWHM) focused spots on a wafer printing surface. The focus spots are intensity-modulated by means of microshutter modulators and are raster-scanned across a wafer surface to create a digitally synthesized exposure image. The system uses a two-stage microlens configuration to achieve both a high fill factor and acceptable transmission efficiency. EUV illumination is supplied by a 6 kHz xenon plasma source, and the illumination optics comprise an aspheric condenser mirror, a spherical collimating mirror, and two sets of flat, terraced fold mirrors that partition the illumination into separate illumination fields covering individual microlens arrays. (The system has no projection optics, because the image modulator elements are integrated with the microlens arrays.) The printing throughput is estimated to be 62 (300-mm) wafers per hour (assuming a resist exposure threshold of 20 mJ/cm2), and print resolution is estimated at 70 nanometers for mixed positive- and negative-tone patterns (at k1=0.6).
235 Citations
33 Claims
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1. A printing exposure apparatus comprising a radiation source, an illumination system, a modulator mechanism, a printhead, and a scanning mechanism, wherein
the printhead comprises a printhead aperture and an array of printer pixels distributed across the printhead aperture, each pixel comprises a sequence of corresponding microlenses, which are symbolically designated as L1, L2, . . . , LN, wherein N is an integer greater than 1, the illumination system conveys radiation from the radiation source to the printhead, whereupon the first microlens L1 in each sequence receives illuminating radiation, each microlens Lm other than the last microlens LN in the sequence focuses the illuminating radiation onto the next corresponding microlens Lm+1, the last microlens LN in each sequence focuses the illuminating radiation onto a corresponding focal point on a printing surface, the modulator mechanism modulates the radiation, whereby the focal points'"'"' exposure intensity levels are controllably varied, the modulator mechanism is a spatial light modulator comprising an array of modulator elements, each pixel further comprises one such modulator element disposed between that pixel'"'"'s microlens L1 and the printing surface, the exposure intensity at each pixel'"'"'s corresponding focal point is modulated independently of other pixels, and the scanning mechanism establishes relative motion between the printing surface and the printhead in synchronization with the modulator mechanism as the printing surface is exposed, whereby a synthesized, high-resolution exposure image is formed on the printing surface.
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2. A printing exposure apparatus comprising a radiation source, an illumination system, a modulator mechanism, a printhead, and a scanning mechanism, wherein
the printhead comprises a printhead aperture and an array of printer pixels distributed across the printhead aperture, each pixel comprises a sequence of corresponding microlenses, which are symbolically designated as L1, L2, . . . , LN, wherein N is an integer greater than 1, the illumination system conveys radiation from the radiation source to the printhead, whereupon the first microlens L1 in each sequence receives illuminating radiation, each microlens Lm other than the last microlens LN in the sequence focuses the illuminating radiation onto the next corresponding microlens Lm+1, the last microlens LN in each sequence focuses the illuminating radiation onto a corresponding focal point on a printing surface, the modulator mechanism modulates the radiation before it is conveyed to the printhead and all the focal points'"'"' exposure intensity levels are subjected to the same modulation, and the scanning mechanism establishes relative motion between the printing surface and the printhead in synchronization with the modulator mechanism as the printing surface is exposed, whereby a synthesized, high-resolution exposure image is formed on the printing surface.
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3. A printing exposure apparatus comprising:
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a radiation source;
a printhead comprising a printhead aperture and an array of printer pixels distributed across the printhead aperture, wherein each pixel comprises a sequence of corresponding microlenses including at least first and last microlenses, and a modulator element disposed between the first microlens and the printing surface;
an illumination system that conveys radiation from the radiation source to the printhead, whereupon for each pixel in the printhead the first microlens in the sequence receives illuminating radiation, each microlens other than the last microlens in the sequence focuses received illuminating radiation onto the next corresponding microlens, and the last microlens in the sequence focuses received illuminating radiation onto a corresponding focal point on a printing surface;
a modulator control mechanism that controls the modulators in the printhead independently of each other so that the exposure intensity at each pixel'"'"'s corresponding focal point is modulated independently of other pixels; and
a scanning mechanism that establishes relative motion between the printing surface and the printhead in synchronization with the modulator control mechanism as the printing surface is exposed. - View Dependent Claims (21, 23, 24, 25, 30)
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4. A printing exposure apparatus comprising:
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a radiation source;
a printhead comprising a printhead aperture and an array of printer pixels distributed across the printhead aperture, wherein each pixel comprises a sequence of corresponding microlenses including at least first and last microlenses, and an illumination system that conveys radiation from the radiation source to the printhead, whereupon for each pixel in the printhead the first microlens in the sequence receives illuminating radiation, each microlens other than the last microlens in the sequence focuses received illuminating radiation onto the next corresponding microlens, and the last microlens in the sequence focuses received illuminating radiation onto a corresponding focal point on a printing surface;
a modulator mechanism that modulates the radiation before it is conveyed to the printhead so that the exposure intensity at each pixel'"'"'s corresponding focal point is subjected to the same modulation; and
a scanning mechanism that establishes relative motion between the printing surface and the printhead in synchronization with the modulator control mechanism as the printing surface is exposed.
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Specification