WO1999042902A2 - Systemes optiques d'imagerie par reflexion a distorsion equilibree - Google Patents

Systemes optiques d'imagerie par reflexion a distorsion equilibree Download PDF

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Publication number
WO1999042902A2
WO1999042902A2 PCT/US1999/003767 US9903767W WO9942902A2 WO 1999042902 A2 WO1999042902 A2 WO 1999042902A2 US 9903767 W US9903767 W US 9903767W WO 9942902 A2 WO9942902 A2 WO 9942902A2
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WO
WIPO (PCT)
Prior art keywords
reflective
substrate
focusing optics
reflective element
radiation
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Ceased
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PCT/US1999/003767
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WO1999042902A3 (fr
Inventor
Henry N. Chapman
Russell M. Hudyma
David R. Shafer
Donald W. Sweeney
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University of California Berkeley
University of California, San Diego
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University of California Berkeley
University of California, San Diego
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Priority claimed from US09/027,281 external-priority patent/US5973826A/en
Priority claimed from US09/094,420 external-priority patent/US6226346B1/en
Application filed by University of California Berkeley, University of California, San Diego filed Critical University of California Berkeley
Priority to AU41803/99A priority Critical patent/AU4180399A/en
Publication of WO1999042902A2 publication Critical patent/WO1999042902A2/fr
Publication of WO1999042902A3 publication Critical patent/WO1999042902A3/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70—Microphotolithographic exposure; Apparatus therefor
    • G03F7/70216—Mask projection systems
    • G03F7/70233—Optical aspects of catoptric systems, i.e. comprising only reflective elements, e.g. extreme ultraviolet [EUV] projection systems
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B17/00—Systems with reflecting surfaces, with or without refracting elements
    • G02B17/02—Catoptric systems, e.g. image erecting and reversing system
    • G02B17/06—Catoptric systems, e.g. image erecting and reversing system using mirrors only, i.e. having only one curved mirror
    • G02B17/0647—Catoptric systems, e.g. image erecting and reversing system using mirrors only, i.e. having only one curved mirror using more than three curved mirrors
    • G02B17/0657—Catoptric systems, e.g. image erecting and reversing system using mirrors only, i.e. having only one curved mirror using more than three curved mirrors off-axis or unobscured systems in which all of the mirrors share a common axis of rotational symmetry
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B13/00—Optical objectives specially designed for the purposes specified below
    • G02B13/22—Telecentric objectives or lens systems

Definitions

  • This invention is related to an optical system for use with short wavelength radiation in photolithography equipment used in the manufacture of semiconductor devices.
  • Photolithography is a well known manufacturing process used to create devices upon substrates. The process typically involves exposing a patterned mask to collimatcd radiation, producing patterned radiation, which is passed through an optical reduction system. The reduced patterned radiation or mask image is projected onto a substrate coated with photoresist. Radiation exposure changes the properties of the photoresist allowing subsequent processing.
  • Photolithography machines use two common methods of projecting a mask image onto a substrate: “step and repeat” and “step and scan” ,
  • the step and repeat method sequentially exposes portions of a substrate to a mask image.
  • the step and repeat optical system has a projection field which is large enough to project the entire mask image onto the substrate. After each image exposure, the substrate is repositioned and the process is repeated.
  • the step and scan method scans a mask image onto a substrate through a slit. Referring to Figure 1, a ring field lithography system
  • a moving mask 101 is illuminated by a radiation beam 103, which reflects off the mask 101 and is directed through a reduction ring field optical system 107. Within the optical system 107, the image is inverted and the arcuate shaped ring field 109 is projected onto a moving substrate 111.
  • the arcuate slit shaped reduced image beam 109 can only project a portion of the mask 101, thus the image beam 109 must scan the complete mask 101 onto the substrate 111. Because the mask
  • the mask 101 and substrate 111 move synchronously, a sharp image is scanned onto the substrate 111. Once the complete mask 101 is scanned onto the substrate, the mask 101 and substrate 111 are repositioned and the process is repeated.
  • the dimensions of the slit are typically described by a ring field radius and a ring field width.
  • the minimum resolution dimension which can be achieved with reduced pattern radiation decreases allowing more electronic components to be fabricated within a given area of a substrate.
  • the number of devices that can be fabricated within an area of substrate is known as device density,
  • a common measure of device density is the amount of memory that can be fabricated on a single DRAM chip.
  • DRAM memory size increases dramatically. With existing technology, 0.25 ⁇ m resolution is possible.
  • R ( ⁇ )/(NA)
  • Kj a process dependent constant (typically 0,7)
  • ⁇ the wavelength of the radiation
  • NA the numerical aperture of the optical system projecting the mask imago.
  • NA numerical aperture
  • EUV radiation ⁇ less than about 15 nm
  • EUV radiation can be focused reflectively using optical elements with multilayer coatings.
  • Step and scan optical systems have inherently less distortion than step and repeat systems due to the reduced field size.
  • the distortion can be readily corrected over the narrow slit width in the direction of scan Step and scan optical systems typically utilize ring fields.
  • an image is projected by the optical system onto the wafer through an arcuate ring field slit 201, which is geometrically described by a ring field radius 203, a ring field width 205 and a length 207. Ring field coverage is limited to 180 * in azimuth.
  • FIG. 3 illustrates the potential for non-uniform reflectivity resulting from high and wide ranges of incidence angles from a uniform multilayer optical element 305.
  • Beams 301 and 303 have incident angles of 10' and 15°, which correspond to multilayer reflectivities of 69% and 40%, respectively.
  • the intensity of reflected beam 309 is less than the intensity of reflected beam 311 because the incidence angle of beam 303 lies in a lower reflectivity region than the incidence angle of beam 301. This difference in the resulting reflectivity creates an apodization in the exit pupil of the imaging system that leads to a loss in linewidth control in the projected image.
  • graded reflective optics can address the intensity apodization problem, graded reflective optics are nonetheless undesirable because they are difficult to fabricate and test.
  • U.S. Patent No. 5,353,322 discloses 3-mirror and 4-mirror optical systems for EUV projection lithography.
  • An extra fold mirror added to the 3-mirror embodiment creates a 4-mirror system that solves the wafer/mask clearance problem presented by a system with an odd number of reflections. However, this mirror does not provide any reflective power and thus provides no aberration correction.
  • Another drawback of the '322 optical system is that its aperture stop is physically inaccessible. Because these systems have no physically accessible hard aperture stop to define the imaging bundle from each field point in a like manner, the projected imagery could vary substantially across the ring field as the different hard apertures in the system vignette or clip the imaging bundles. This vignetting or clipping can lead to loss of critical dimension (CD) control in the projected image at the wafer.
  • CD critical dimension
  • the present invention is directed to a reflective optical system that addresses the above and other problems. More specifically, the present invention is a four mirror optical system which allows a reduced mask image to be projected onto a wafer with short wavelength radiation. The present invention allows higher device density because resolution is improved.
  • the present invention also improves wafer throughput.
  • the reflective optics have been configured to improve radiation throughput by improving optical clement reflectivity.
  • the optical elements have been configured with radiation beam incidence angles as close as possible to perpendicular. The acceptable ranges of incidence angles have also been minimized to preserve uniform reflectivity and to eliminate the need for graded optics, which can add significant risk and cost to the system.
  • the inventive optical system further minimizes manufacturing costs by not requiring highly aspheric optical elements.
  • the present invention includes an accessible aperture stop.
  • the present invention also has a balanced centroid distortion curve across the ring field width. More specifically, the centroid distortion levels at the edges of the ring field width are substantially equal and quantitatively higher than the centroid distortion at the center of the ring field width. By balancing the centroid distortion curve across the ring field width, the dynamic distortion is minimized improving substrate throughput.
  • the present invention is directed to 4-mirror reflective optical systems that have high resolution, high numerical aperture, and balanced distortion.
  • the present invention allows higher device density because resolution is increased.
  • the reflective optics have been configured to improve radiation throughput by improving optical element reflectivity.
  • the optical elements have been configured with radiation beam incidence angles as close as possible to perpendicular.
  • the acceptable ranges of incidence angles have also been minimized to preserve uniform reflectivity and to eliminate the need for graded multilayer optics, which can add significant risk ' to the system.
  • the inventive optical systems further minimize manufacturing risks by not requiring highly aspheric optical elements.
  • the present invention includes an accessible aperture stop.
  • the present invention also has a balanced centroid distortion curve across the ring field width. More specifically, the centroid distortion levels at the edges of the ring field width are substantially equal and quantitatively higher than the centroid distortion at the center of the ring field width. By balancing the static centroid distortion curve across the ring field width, the dynamic distortion is minimized.
  • Figure 1 is a view of a prior art ring field lithography system.
  • Figure 2 is a view of a ring field slit.
  • Figure 3 is a view of two radiation beams incident upon a reflective element.
  • Figure 4 is a schematic depiction of the main elements of the exemplary EUV lithography apparatus according to the present invention.
  • Figure ⁇ A is a schematic depiction of the main elements of the exemplary EUV lithography apparatus according to the present invention.
  • Figure 5 is a view of one embodiment of the optical system according to the present invention.
  • Figure 6 is a graph showing distortion v. position across the ring field width for one embodiment of the optical system.
  • Figure 7 is a graph showing reflectivity v. wavelength for a Mo/Si multilayer reflective coating.
  • Figure 8 is a graph showing reflectivity v. angle of incidence for a low incidence angle reflective Mo/Si multilayer reflective coating.
  • FigureSA is a view of another embodiment of the optical system according to the present invention.
  • Figure 9 is a graph showing reflectivity v. angle of incidence for a high incidence angle reflective Mo/Si multilayer reflective coating.
  • Figure"A j s a graph showing the centroid distortion v. position across the ring field width for the embodiment shown in Figure 8A .
  • the present invention is a photolithography optical system designed for use with extreme ultraviolet (EUV) radiation.
  • Figure 4 schematically depicts the exemplary inventive apparatus for semiconductor EUV lithography.
  • the apparatus comprises a radiation source 401 that emits EUV radiation 403.
  • the EUV radiation 403 is processed by a condenser 405 which produces a EUV beam 403' to uniformly illuminate a portion of mask 407.
  • the radiation reflected or transmitted from the mask 407 produces a patterned EUV beam 403" which is introduced into optical system 409.
  • the optical system 409 projects a reduced image of the mask 407 onto a wafer 411.
  • EUV radiation has a wavelength ⁇ between about 4 to 20 nm and may be produced by any suitable means including laser produced plasma, synchrotron radiation, electric discharge sources, high-harmonic generation with femto-second laser pulses, discharge-pumped x-ray lasers and electron- beam driven radiation devices.
  • Laser-produced plasma (LPP) sources focus an intense pulsed laser beam onto a target. Suitable targets are metals and noble
  • Targets of noble gas molecule clusters in a supersonic jet produce a bright "spark" with a broad emission spectrum from the visible to the EUV radiation.
  • An LLP xenon gas source converts about 0.8% of the incident laser power into EUV light in the required spectral bandwidth.
  • High-repetition- rate (3,000 - 6,000 Hz) pulsed laser drivers deliver 1,500 W of focused power to the target regions.
  • Other suitable targets include gold, tantalum, tungsten and copper.
  • the condenser collects EUV power from the LLP source and conditions the radiation to uniformly illuminate the mask.
  • the condenser provides the EUV radiation in a narrow ring field with at least 1% uniformity at the mask in the cross scan dimension.
  • the condenser further directs the EUV beam into the entrance pupil of the inventive optical system with a partial coherence of approximately 0.7. Separate collection channels each act in parallel directing radiation across the entire ring field and the optical system entrance pupil.
  • the inventive optical system comprises four reflective optical elements listed in order from mask to substrate: Ml, M2, M3 and M4.
  • the optical system is placed in a vacuum or other suitable atmosphere.
  • FIG. 5 there is shown an exemplary optical system for EUV semiconductor lithography. Because this is a ring field optical configuration, only the lower section of the first optical element Ml 505, the lower section of the second optical element M2 509, all of the third optical element M3 513, and the upper section of the fourth optical element M4 517 are exposed to EUV radiation.
  • the optical elements are all arranged in a coaxial configuration. The portions of the mirrors actually used are designated with solid lines and the virtual non-existent portions are designated with dotted lines.
  • Beaml 501 diverges from mask 503 onto convex aspheric mirror Ml 505.
  • the mask 503 is reflective.
  • Beam2 507 is reflected from mirror Ml 505 in a divergent cone to a concave aspheric mirror M2 509.
  • Beam3 511 is reflected from mirror M2 509 in a convergent cone to a convex spherical mirror M3 513, which also functions as an aperture stop.
  • Beam4 515 is reflected from mirror M3 513 in a divergent cone to a concave aspheric mirror M4 517.
  • Bea ⁇ 519 is reflected from mirror M4 517 in a convergent cone, projecting a reduced image of the mask 503 pattern onto a wafer 521.
  • the chemical reaction of a photoresist layer on the wafer 521 to the patterned EUV exposure enables subsequent semiconductor processing by well known means.
  • Concave mirrors have positive optical power and convex mirrors have negative optical power.
  • the optical power configuration of the inventive system from object to image can be described as: negative, positive, negative and positive, corresponding to mirrors Ml 505, M2 509, M3 513 and M4 517 respectively.
  • This inventive placement of optical power allows the projection system to produce a reduction ratio of 4x and a telecentric imaging bundle at the wafer (substrate plane), while simultaneously providing the necessary op to-mechanical clearances and achieving a near-zero Petzval sum (flat field condition).
  • the numerical aperture of the system is 0.1.
  • the absolute radii of the mirrors Ml 505, M2 509, M3 513 and M4 517, relative to the system focal length, are listed in Table 2.
  • Table 2 The axial separations of the mirrors Ml 505, M2509, M3 513 and M4 517, relative to the system focal length, are listed in Table 3. For a four to one reduction, the distance of the mask to Ml 305 is 1005.654 mm.
  • the inventive optical system projects a mask image onto a wafer through the step and scan method.
  • the usable field projected by the inventive optical system is in the form of an arcuate slit 201.
  • the inventive optical system can be configured with length 707 of 26 mm at an angle 209 of approximately 30°, a ring field width 205 of 1.5 mm and a ring field radius 203 of 52,75 mm.
  • the inventive system achieves a resolution of 0.1 ⁇ m or better with a depth of focus greater than 1 ⁇ m across the arcuate slit 201.
  • Tine inventive optical system arcuate slit 201 dimensions arc an improvement over the prior art.
  • the prior art typically produced an arcuate slit 201 with length 207 (approximately 16 mm) at an angle 209 (approximately 60°), a ring field width 205 (approximately 0.5 mm to 1.0 mm) and a ring field radius 203 (approximately 31.5 mm),
  • the ring field width 205 of the present invention (1-5 mm) is significantly wider than that of the prior art. Because the ring field radius 203 of the present invention is larger than that of the prior art, the present invention improves the unit area coverage within a single field on the wafer, thereby improving wafer throughput per hour.
  • Tables 3-5 contain constructional data and other relevant information for the inventive optical system shown in Figure 5.
  • the inventive optical system is a telecentric ring field system with a 1.5 mm slit width, a 4 ; 1 reduction ratio and a 0.1 numerical aperture (NA).
  • the reference wavelength is 13,4 mm.
  • Table 4 shows the mirror radii and spacings, and taken with Table 5 and Table 6, completely describes the apparatus of the example.
  • Table 5 lists the aspheric constants.
  • the aspheric profile is uniquely determined by its K, A, B, C, and D values.
  • the sag of the aspheric surface (through 10th order) parallel to the z- axis (z) is given by:
  • h is the radial coordinate
  • c is the curvature of the surface (1/R)
  • A, B, C, and D are the 4th, 6th, 8th, and 10th order deformation coefficients, respectively.
  • the equation coefficients A and D are zero for the mirrors Ml, M2 and M4, thus they use only 6th and 8th order polynomial deformations.
  • the optical elements Ml, M2, M3 and M4 can be described via the base conic as hyperboloid, prolate ellipse, sphere and oblate ellipse, respectively.
  • Another advantage of the present invention is that the centroid distortion magnitude is balanced across the ring field width. This balance distortion curve results in a minimization of dynamic (scanning) distortion.
  • centroid distortion curve of the inventive optical system is shown.
  • the centroid location is the geometric center of an arcuate radiation ray imaged from a point on the mask to the wafer (substrate).
  • the distortion curve is balanced when the shape of the centroid distortion curve is quadratic across the ring Held width and the point of inflection of the curve is located substantially at the center of the ring field width.
  • the shape of the curve may be either 'TJ" or W with the magnitude of distortion substantially equal at the edges of the ring field width.
  • the balanced static centroid distortion curve of the present invention is obtained by adjusting the asphericity of optical elements Ml, M2 and M4.
  • the distortion in an optical system can be expanded in a power series of odd terms, v/ith the 3rd and 5th order terms being the lowest ones.
  • the 3rd and the 5th order static distortions can be adjusted so that the centroid distortion is symmetrically balanced across the ring field width.
  • These aspheric surfaces on Ml, M2, and M4 also help correct astigmatism across the ring.
  • the aspheric surfaces can also be expanded as a departure from a base sphere as a function of aperture radius in a power series of even terms.
  • the expansion of the distortion and the aspheric surfaces are interrelated in that the 4th and 6th order aspheric terms influence the 3rd and 5th order distortion terms.
  • the magnitude and sign (+ or -) of the 3rd and 5th order distortion terms can be controlled.
  • the prior art systems adjusted the aspherics terms in order to minimize the overall distortion across the ring field slit width, but not to shape the distortion curve, thus the dynamic (scanning) distortions were never optimized.
  • Table 7 below shows the deviation (distortion) of the image centroid at the wafer from its ideal location.
  • Table 7 In scanning lithography, the mask and wafer are synchronously scanned so that the projected ring field at the mask will cover the entire wafer field.
  • the scanning process has a substantial effect on the image aberrations, particularly distortion.
  • the image distortion due to the relative movement of the image and the substrate during radiation exposure is dynamic distortion which can smear an image out along a field-dependent trajectory as the image crosses the ring field width.
  • Rtotal Rl x Rz x R3 x R , where R x represents the reflectivity of Mirror x .
  • Different reflective coatings have different reflectivities. Reflective coatings, which have been found to have acceptable EUV reflectivity, include multilayer coatings of molybdenum/silicon (Mo/Si) and molybdenum/beryllium (Mo/Be). The maximum theoretical reflectivity of a multilayer mirror made of Mo /Si is approximately 72%.
  • the Mo/Si multilayer structure includes an alternating layer stack of Mo and Si.
  • the Mo and Si layers are deposited in a de-magnetron sputtering system or an ion beam sputtering system. The thickness of each layer was determined by simultaneously maximizing the constructive interference of the beams reflected at each interface and minimizing the overall absorption to enable more interfaces to contribute to the reflectance.
  • the optical elements In addition to being highly reflective, the optical elements must have extremely accurate surface figures and surface roughness. State-of-the-art techniques arc used to fabricate mirror surface figures with an accuracy of about 0.25 nm rms or better. Interferometers are used to measure the dimensional accuracy of the figure of the aspheric mirrors and the wavefront of assembled projection. Commercially available tools are capable of measuring surface roughness.
  • Shifts in radiation wavelength are equivalent to changes in the incidence angle, i.e., both result in reduced reflectivity.
  • the inventive optical system maintains a high overall system reflectivity by utilizing shallow incidence angles which are within the highly reflective region of the multilayer surface.
  • the thickness of the layer coatings can be adjusted to maximize the reflectivity for specific range of incidence angles.
  • the maximum theoretical reflectivity of over 70% for a suitably constructed Mo/Si multilayer optical element is obtained when the radiation incidence angle is 5° ⁇ 5.
  • a bilayer pair constructed using a 2.8 nm thick layer Mo and 4.0 nm thick layer of Si.
  • the reflectivity of this multilayer coating decreases as the incidence angle varies. At incidence angles of 12.5 * and 15 the decreased reflectivity is about 40% and 12%, respectively. Keeping the incidence angles low at Ml, M2, and M4, maximizes the system reflectivity by ensuring that the multilayer is being used at its highest reflectivity at all times.
  • the maximum theoretical reflectivity of over 70% can be shifted to higher incidence angle at the expense of the angular bandwidth of the coating.
  • the Mo/Si multilayer is shifted to about 12* ⁇ 1.
  • the Mo/Si bilayer is now composed of 2.92 n thick layer of Mo and 4.12 nm thick layer of Si. Again, 40 bilayer pairs complete the multilayer stack.
  • the reflectivity of this multilayer coating decreases more rapidly as the incidence angle deviates from 12 1.
  • the decreased reflectivities are approximately 55% and 40%, respectively.
  • the reflectivity M3 is maximized by using reflective optics specifically designed for incidence angles between approximately 11 * and 13".
  • Table 8 Another benefit of the inventive optical system configuration is that the intensity of the illumination in the imaging bundle is uniform without the use of complex graded multilayer coatings. Prior art optical systems may require graded multilayer coatings to achieve this same level of illumination uniformity. Another benefit of the inventive optical system is the minimization of high radiation intensity and heat generation which can degrade the reflective coating and cause thermal distortion of the optical element. Because the inventive system has a high total reflectivity, the absorbed energy is minimized. The inventive system is also able to dissipate the absorbed energy more readily because mirror Ml has a large surface area. By spreading the radiation energy across a broader surface area, the radiation intensity and resulting heat generation are minimized.
  • the inventive optical system requires only low aspheric mirrors, which are significantly easier to test and fabricate than highly aspheric mirrors. Mirrors with asphericities less than approximately 10 micrometers (low asphericity) can be tested at the center of curvature without the need for complex auxiliary test optics. In addition, low asphericity mirrors are more easily polished to an excellent surface finish of less than one angstrom. Table 9 below shows the maximum aspheric departure from a best-fit spherical surface centered on the off-axis section of the parent asphere for each mirror.
  • mirror M3 may also be aspheric, with a maximum departure of ⁇ 2.0 ⁇ m from the best fit sphere.
  • the design has an accessible, real aperture stop on mirror M3.
  • the accessible aperture stop makes the projected imagery stationary.
  • the imagery is independent of the position in the ring field. More specifically, the accessible aperture stop ensures that imaging bundles from each field point are not clipped or vignetted across the ring field width.
  • M3 is configured with at least 5 mm of clearance around its diameter from other radiation beams making it accessible for adjustment.
  • optical system shown in Figure 5 is in no way limited to use with a particular type of li t hography system or a particular lithography machine. Those skilled in the art will also readily appreciate that the optical system may be used with any similar lithography mechanism. It is intended that all such modifications,
  • the present invention is a photolithography optical system designed for use with extreme ultraviolet (EUV) radiation.
  • FigureHAschematically depicts the exemplary inventive apparatus for semiconductor EUV lithography.
  • the apparatus comprises a radiation sourceMHA that emits EUV radiation 403 ⁇ .
  • the EUV radiation ⁇ * is processed by a condensed ⁇ 5 A w hi cn produces a EUV beamH ⁇ iAto uniformly illuminate a portion of mask 4 o ⁇ f .
  • the radiation reflected from the mask 4W f) produces a patterned EUV beam HHA. which is introduced into optical system 4t 3 A ⁇
  • the optical system 413 A projects a reduced image Ml ⁇ Aof the maskHWA onto a wafer 417A .
  • EUV radiation has a wavelength ⁇ between about 4 to 20 nm and may be produced by any suitable means, including laser produced plasma, synchrotron radiation, electric discharge sources, high-harmonic generation with femto- ⁇ econd laser pulses, discharge-pumped x-ray lasers and electron- beam driven radiation devices.
  • Laser-produced plasma (LPP) sources focus an intense pulsed laser beam onto a target.
  • Suitable targets are metals and noble gases.
  • Targets of noble gas molecule clusters in a supersonic jet produce a bright "spark” with a broad emission spectrum from the visible to the EUV radiation.
  • High-repetition-rate (3,000 - 6,000 Hz) pulsed laser drivers deliver 1,500 W of focused power to the target regions.
  • the LPP gas source then converts the incident laser power into EUV light in the required spectral bandwidth.
  • the condenser collects EUV power from the LPP source and conditions the radiation to uniformly illuminate the mask.
  • the condenser provides the EUV radiation in a narrow ring field with at least 1% uniformity at the mask in the cross scan dimension,
  • the condenser further directs the EUV beam into the entrance pupil of the inventive optical system with a partial coherence of approximately 0.7.
  • Separate collection channels each act in parallel, directing radiation across the entire ring field and the optical system entrance pupil.
  • the inventive optical system comprises four reflective optical elements (mirrors) listed in order from mask to substrate: Ml, M2, M3 and M4.
  • the optical system is placed in a vacuum or other suitable atmosphere.
  • EUV rays are collimated and directed at a mask, producing patterned radiation.
  • the object end of the inventive optical system departs enough from telecentricity so that a reflective mask can be used without any vignetting of the light rays by mirror edges.
  • an exemplary optical system is shown for EUV semiconductor lithography. Because this is a ring field optical configuration, the lower section of the first optical element Ml 505, the lower section of the second optical element M2 509, all of the third optical element M3 513, and the upper section of the fourth optical element M4 517 are exposed to EUV radiation.
  • the optical elements are all arranged in a coaxial configuration.
  • the portions of the mirrors actually used are designated with solid lines, and the sections of the parent mirror that are not used are designated with dotted lines.
  • An EUV Beam 1 501 diverges from a reflective mask 503 onto convex aspheric mirror Ml 505.
  • Beam 2 507 is reflected from mirror Ml 505 in a divergent cone to a concave aspheric mirror M2 509.
  • Beam 3 511 is reflected from mirror M2 509 in a convergent cone to a convex spherical mirror M3 513, which also functions as an aperture stop
  • Beam 4 515 is reflected from mirror M3 513 in a divergent cone to a concave aspheric mirror M4 517.
  • Beam 5 519 is reflected from mirror M4 517 in a convergent cone, projecting a reduced image of the mask 503 pattern onto a wafer 521.
  • the chemical reaction of a photoresist layer on the wafer 521 to the patterned EUV exposure enables subsequent semiconductor processing by well-known means.
  • Concave mirrors have positive optical power and convex mirrors have negative optical power.
  • the optical power configuration of the first embodiment of the inventive system from object to image can be described as: negative, positive, negative and positive, corresponding to mirrors Ml 505, M2 509, M3 513, and M4 517, respectively.
  • This inventive placement of optical power allows the projection system to produce a reduction ratio of 4x and a telecentric imaging bundle at the wafer that is normal to the wafer (substrate plane), while simultaneously providing the necessary opto- 5 mechanical clearances and achieving a near-zero Petzval sum (flat field condition).
  • the numerical aperture of the system is about 0.1.
  • the absolute radii of the mirrors Ml 505, M2 509, M3 513, and M4 517, relative to the system focal length, are listed in Table 1 A .
  • Table 1 The axial separations of the mirrors Ml 505, M2 509, M3 513 and M4 10 517, relative to the system focal length, are listed in Table 2A.For a 4-to ⁇ l reduction, the distance of the mask to Ml 305 is 1005.654 mm.
  • the inventive optical system projects a mask image onto a wafer through the step and scan method.
  • the usable field projected by the inventive optical system is in the form of an arcuate slit 201.
  • the inventive optical system can be configured with length 207 of 26 mm at an angle 209 of approximately 30', a ring field width 205 of 1.5 mm and a ring field radius 203 of 52.75 mm.
  • the inventive system achieves a resolution of 0.1 ⁇ m or better with a depth of focus greater than 1 ⁇ m across the projected image field.
  • the inventive optical system arcuate slit dimensions are an improvement over the prior art.
  • the prior art typically produced an arcuate slit with a length of approximately 16 mm at an angle of approximately 60', a ring field width of approximately 0.5 mm to 1.0 mm, and a ring field radius of approximately 31.5 mm.
  • the ring field width of the present invention (1.5-3.0 mm) is significantly wider than that of the prior art. Because the ring field radius of the present invention is larger than that of the prior art, the present invention improves the unit area coverage within a single field on the wafer, thereby improving wafer throughput per hour.
  • the inventive optical system is a telecentric ring field system with a slit width of 1.5-3.0 mm, a 4:1 reduction ratio, and a numerical aperture (NA) of at least 0.1 ,
  • the reference wavelength is 13.4 mm.
  • Tabled shows the mirror radii and spacings, and taken with Table 4 r and TableSn, completely describes the apparatus of the example. Tabled lists the aspheric constants. TableGAshows the performance of the system as described by the root mean square (RMS) wavefront error and corresponding Strehl ratio.
  • RMS root mean square
  • the aspheric profile is uniquely determined by its K, A, B, C, and D values, such as given in Table 4A.
  • the sag of the aspheric surface (through 10th order) parallel to the z-axis (z) is given by Equation 1:
  • h Is the radial coordinate
  • c is the curvature of the surface (1/R)
  • A, B, C, and D are the 4th, 6th, 8th, and 10th order deformation coefficients, respectively.
  • the equation coefficients ⁇ and D are zero for the mirrors Ml, M2, and M4, thus they use only 6th and 8th order polynomial deformations.
  • the optical elements Ml, M2, M3, and M4 can be described via the base conic as a hyperboloid, prolate ellipse, sphere, and oblate spheroid, respectively.
  • Another advantage of this first embodiment of the present invention is that the centroid distortion magnitude is balanced across the ring field width.
  • centroid distortion curve results in a minimization of dynamic (scanning) distortion.
  • the centroid location is the geometric center of an arcuate radiation ray imaged from a point on the mask to the wafer (substrate).
  • the distortion curve is balanced when the shape of the centroid distortion curve is quadratic across the ring field width, and the point of inflection of the curve is located substantially at the center of the ring field width.
  • the shape of the curve may be either "U" or "n", depending on how the input field was defined at the mask, and with the magnitude of distortion substantially equal at the edges of the ring field width.
  • the balanced static centroid distortion curve of the present invention is obtained by adjusting the asphericity of optical elements Ml, M2, and M4.
  • the distortion in an optical system can be expanded in a power series of odd terms, with the 3rd and 5th order terms being the lowest ones.
  • the 3rd and the 5th order static distortions can be adjusted so that the centroid distortion is symmetrically balanced across the ring field width.
  • These aspheric surfaces on Ml, M2, and M4 also help correct astigmatism across the ring,
  • the aspheric surfaces can also be expanded as a departure from a base sphere as a function of aperture radius in a power series of even terms.
  • the expansion of the distortion and the aspheric surfaces are interrelated in that the 4th and 6th order aspheric terms influence the 3rd and 5th order distortion terms.
  • the magnitude and sign (+ or -) of the 3rd and 5th order distortion terms can be controlled.
  • the prior art systems adjusted the aspherics terms in order to minimize the overall distortion across the ring field slit width, but not to shape the distortion curve, thus the dynamic (scanning) distortions were never optimized.
  • the mask and wafer are synchronously scanned so that the projected ring field at the mask will cover the entire wafer field.
  • the scanning process has a substantial effect on the image aberrations, particularly distortion.
  • the image distortion due to the relative movement of the image and the substrate during radiation exposure is dynamic distortion which can smear an image out along a field-dependent trajectory as the image crosses the ring field width.
  • Some of the radiation incident to the optical elements is reflected, a large percentage of the incident radiation is absorbed.
  • the total reflectivity of a four mirror optical system is described by the formula: Riotal j x 2 x R3 x R4, where R x represents the reflectivity of Mirror x .
  • Different reflective coatings have different reflectivities.
  • Reflective coatings which have been found to have acceptable EUV reflectivity, include multilayer coatings of molybdenum/silicon (Mo/Si) and molybdenum/beryllium (Mo/ Be).
  • Mo/Si molybdenum/silicon
  • Mo/ Be molybdenum/beryllium
  • the maximum theoretical reflectivity of a multilayer mirror made of Mo/Si is approximately 72%.
  • the Mo/Si multilayer structure includes an alternating layer stack of Mo and Si.
  • the Mo and Si layers are deposited by a dc-magnetron sputtering system or an ion beam sputtering system. The thickness of each layer is determined by simultaneously maximizing the constructive interference of the beams reflected at each interface and minimizing the overall absorption to enable more interfaces to contribute to the reflectance.
  • the optical elements In addition to being highly reflective, the optical elements must have extremely accurate surface figures and surface roughness. State-of-the-art techniques are used to fabricate mirror surface figures with an accuracy of about 0.25 nm rms or better. Interferometers are used to measure the dimensional accuracy of the figure of the aspheric mirrors and the wavefront of assembled projection, Commercially available tools are capable of measuring surface roughness.
  • Shifts in radiation wavelength are equivalent to changes in the incidence angle, i.e., both result in reduced reflectivity.
  • the inventive optical systems maintain a high overall system reflectivity by utilizing shallow incidence angles that are within the highly reflective region of the multilayer surface, The thickness of the layer coatings can be adjusted to maximize the reflectivity for a specific range of incidence angles.
  • the maximum theoretical reflectivity of over 70% for a suitably constructed Mo/Si multilayer optical element is obtained when the radiation incidence angle is 5° ⁇ 5. At incidence angles of 12.5' and 15", the reflectivity decreases to about 40% and 12%, respectively. Keeping the incidence angles low at Ml, M2, and M4, maximizes the system reflectivity by ensuring that the multilayer is being used at its highest reflectivity at all times.
  • the maximum theoretical reflectivity of over 70% can be shifted to higher incidence angles at the expense of the angular bandwidth of the coating.
  • the design of the Mo/Si multilayer is adjusted so the reflectance peak is shifted to about 12 * ⁇ 1, where the reflectivity of this multilayer coating decreases more rapidly as the incidence angle deviates from 12".
  • the reflectivities decrease to approximately 55% and 40%, respectively.
  • the reflectivity M3 is maximized by using reflective optics specifically designed for incidence angles between approximately 11° and 13 * .
  • a benefit of the inventive optical system configuration is that the intensity of the illumination in the imaging bundle is uniform without the use of complex graded multilayer coatings.
  • Prior art optical systems may require graded multilayer coatings to achieve this same level of illumination uniformity.
  • the high radiation intensity and heat generation which can degrade the reflective coating and cause thermal distortion of the optical element, is minimized.
  • the inventive system has a high total reflectivity, the absorbed energy is minimized.
  • the inventive system is also able to dissipate the absorbed energy more readily because mirror Ml has a large surface area. By spreading the radiation energy across a broader surface area, the radiation intensity and resulting heat generation are minimized.
  • the inventive optical system requires only low aspheric mirrors, which are significantly easier to fabricate and test than highly aspheric mirrors. Mirrors with asphericities less than approximately 12 micrometers (low asphericity) can be tested at the center of curvature without the need for complex auxiliary test optics. In addition, low asphericity mirrors are more easily polished to an excellent surface finish of less than 1A, Table ⁇ Abelow shows the maximum aspheric departure from a best-fit spherical surface centered on the off-axis section of the parent asphere for each mirror.
  • mirror M3 may also be aspheric, with a maximum departure of ⁇ 2.0 ⁇ m from the best fit sphere.
  • the design has an accessible, real aperture stop on mirror M3.
  • the accessible aperture stop makes the projected imagery stationary.
  • the imagery is independent of the position in the ring field.
  • the physically accessible aperture stop ensures that imaging bundles from each field point are not clipped or vignetted across the ring field width.
  • M3 is configured with at least 5 mm of clearance around its diameter from other radiation beams making it accessible for adjustment,
  • Increasing the numerical aperture decreases the ray clearance around mirrors Ml and M3.
  • Ray clearance can be improved substantially by increasing the field bins.
  • the field dependent aberrations become more difficult to correct as the field bias is increased-
  • incident angles at each mirror increases with increasing field bias. This necessarily complicates the multilayer coating task.
  • a better approach to solving the ray clearance problem is to decrease the physical distance from the mask plane to mirror Ml, while reducing the radius of the ring field at the mask to keep the field bias constant. In this manner, the incident angles at each of the mirrors can be constrained to acceptable limits.
  • the reduction ratio of the system decreases as the distance from the mask to Ml is decreased.
  • the negative power of mirror Ml is increased relative to the system focal length.
  • Petzval sum must be substantially zero to achieve high resolution imagery.
  • Table 10 A The axial separations of the mirrors Ml 801, M2 803, M3 805, and M4 807, relative to the system focal length, are listed in Table llA,For a 4-to-l reduction, the distance of the mask to Ml 801 is 726.688 mm.
  • the inventive optical system is a telecentric ring field system with a slit width of about 0.5-3.0 mm, a 4:1 reduction ratio, and a numerical aperture (NA) in the range of about 0.1 to 0.14.
  • the reference wavelength is 13.4 mm.
  • Table UA shows the mirror radii and spacings, and taken with Table 13 A and Table IW A completely describes the apparatus of the example.
  • Table VSA- shows the performance of the system as described by the root mean square (RMS) wavefront error and corresponding Strehl ratio.
  • RMS root mean square
  • the aspheric profile is uniquely determined by its K, A, B, C, and D values, such as given in Table 13A.,Tho sag of the aspheric surface (through 10th order) as a function of radial coordinate (h) given by Equation 1.
  • Mirrors Ml, M2, and M4 are base conies with 6th, 8th, and 10th order polynomial deformations.
  • Mirror M3 has only a 6th order polynomial deformation, Identifying the mirror type via the base conic, the optical elements Ml and M2 are a hyperboloid and prolate ellipsoid, respectively. Both optical elements M3 and M4 are oblate spheroids.
  • This second embodiment also has an accessible, real aperture stop on mirror M3. More specifically, the accessible aperture stop ensures that . imaging bundles from each field point within the ring field are not clipped or vignetted. This helps to ensure that the projected imagery, setting aside the effects of the field dependent aberrations and input illumination, is independent of position in the ring field. Such imagery is termed stationary.
  • Another advantage of this second embodiment of the present invention is that the distortion is balanced across the width of the ring field. This balanced distortion curve results in a minimization of dynamic (scanning) distortion as explained previously. Referring to Figurc ⁇ CVthe centroid distortion curve of this inventive optical system is shown. Table 164 below provides a tabular listing of the deviation of the image centroid its ideal location at the wafer plane. This deviation is the centroid distortion.
  • Table 16 A This second embodiment of the present invention also requires only low aspheric mirrors.
  • Table DAbelow shows the maximum aspheric departure from a best-fit spherical surface centered on the off-axis section of the parent asphere for each mirror. While the listed asphericities are for the preferred embodiment, these asphericities may vary by ⁇ 2.0 ⁇ m for Ml, ⁇ 2.0 ⁇ m for M2, ⁇ 1.0 ⁇ m for M3, and ⁇ 2.0 ⁇ m for M4 for different projection systems.

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  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
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Abstract

L'invention porte sur des systèmes optiques fonctionnant dans l'extrême UV comportant quatre éléments réfléchissant projetant une image masque sur un substrat. Les quatre éléments optiques comprennent dans l'ordre de l'objet vers l'image des miroirs convexe, concave, convexe et concave. Lesdits systèmes sont particulièrement adaptés à des procédés de lithographie par paliers et balayage. L'invention permet d'utiliser des fentes plus larges associées à une optique de balayage à champs annulaire, ce qui augmente la production des tranches et la densité d'implantation des dispositifs à semi-conducteurs. Ces systèmes se caractérisent par une réduction de la distorsion dynamique puisque la distorsion statique est équilibrée le long de la largeur de la fente.
PCT/US1999/003767 1998-02-20 1999-02-19 Systemes optiques d'imagerie par reflexion a distorsion equilibree Ceased WO1999042902A2 (fr)

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US09/027,281 US5973826A (en) 1998-02-20 1998-02-20 Reflective optical imaging system with balanced distortion
US09/027,281 1998-02-20
US09/094,420 US6226346B1 (en) 1998-06-09 1998-06-09 Reflective optical imaging systems with balanced distortion
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EP0962830A1 (fr) * 1998-05-30 1999-12-08 Carl Zeiss Système de quatre miroirs à champ annulaire pour lithographie EUV
US8194230B2 (en) 2006-12-04 2012-06-05 Carl Zeiss Smt Gmbh Projection objectives having mirror elements with reflective coatings
US8902406B2 (en) 2009-11-26 2014-12-02 Carl Zeiss Smt Gmbh Projection objective
US9091843B1 (en) 2014-03-16 2015-07-28 Hyperion Development, LLC Optical assembly for a wide field of view point action camera with low track length to focal length ratio
US9316808B1 (en) 2014-03-16 2016-04-19 Hyperion Development, LLC Optical assembly for a wide field of view point action camera with a low sag aspheric lens element
US9316820B1 (en) 2014-03-16 2016-04-19 Hyperion Development, LLC Optical assembly for a wide field of view point action camera with low astigmatism
US9494772B1 (en) 2014-03-16 2016-11-15 Hyperion Development, LLC Optical assembly for a wide field of view point action camera with low field curvature
US9726859B1 (en) 2014-03-16 2017-08-08 Navitar Industries, Llc Optical assembly for a wide field of view camera with low TV distortion
US9995910B1 (en) 2014-03-16 2018-06-12 Navitar Industries, Llc Optical assembly for a compact wide field of view digital camera with high MTF
US10139595B1 (en) 2014-03-16 2018-11-27 Navitar Industries, Llc Optical assembly for a compact wide field of view digital camera with low first lens diameter to image diagonal ratio
US10386604B1 (en) 2014-03-16 2019-08-20 Navitar Industries, Llc Compact wide field of view digital camera with stray light impact suppression
US10545314B1 (en) 2014-03-16 2020-01-28 Navitar Industries, Llc Optical assembly for a compact wide field of view digital camera with low lateral chromatic aberration
CN113050362A (zh) * 2019-12-27 2021-06-29 中芯国际集成电路制造(上海)有限公司 光学邻近修正方法及掩膜版

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5063586A (en) * 1989-10-13 1991-11-05 At&T Bell Laboratories Apparatus for semiconductor lithography
US5315629A (en) * 1990-10-10 1994-05-24 At&T Bell Laboratories Ringfield lithography
JPH04333011A (ja) * 1991-05-09 1992-11-20 Nikon Corp 反射縮小投影光学装置
US5353322A (en) * 1992-05-05 1994-10-04 Tropel Corporation Lens system for X-ray projection lithography camera
US5805365A (en) * 1995-10-12 1998-09-08 Sandia Corporation Ringfield lithographic camera

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EP0962830A1 (fr) * 1998-05-30 1999-12-08 Carl Zeiss Système de quatre miroirs à champ annulaire pour lithographie EUV
US8194230B2 (en) 2006-12-04 2012-06-05 Carl Zeiss Smt Gmbh Projection objectives having mirror elements with reflective coatings
US8902406B2 (en) 2009-11-26 2014-12-02 Carl Zeiss Smt Gmbh Projection objective
US9995910B1 (en) 2014-03-16 2018-06-12 Navitar Industries, Llc Optical assembly for a compact wide field of view digital camera with high MTF
US10139595B1 (en) 2014-03-16 2018-11-27 Navitar Industries, Llc Optical assembly for a compact wide field of view digital camera with low first lens diameter to image diagonal ratio
US9316820B1 (en) 2014-03-16 2016-04-19 Hyperion Development, LLC Optical assembly for a wide field of view point action camera with low astigmatism
US9494772B1 (en) 2014-03-16 2016-11-15 Hyperion Development, LLC Optical assembly for a wide field of view point action camera with low field curvature
US9726859B1 (en) 2014-03-16 2017-08-08 Navitar Industries, Llc Optical assembly for a wide field of view camera with low TV distortion
US9778444B1 (en) 2014-03-16 2017-10-03 Navitar Industries, Llc Optical assembly for a wide field of view point action camera with low astigmatism
US9784943B1 (en) 2014-03-16 2017-10-10 Navitar Industries, Llc Optical assembly for a wide field of view point action camera with a low sag aspheric lens element
US9091843B1 (en) 2014-03-16 2015-07-28 Hyperion Development, LLC Optical assembly for a wide field of view point action camera with low track length to focal length ratio
US10107989B1 (en) 2014-03-16 2018-10-23 Navitar Industries, Llc Optical assembly for a wide field of view point action camera with low field curvature
US9316808B1 (en) 2014-03-16 2016-04-19 Hyperion Development, LLC Optical assembly for a wide field of view point action camera with a low sag aspheric lens element
US10139599B1 (en) 2014-03-16 2018-11-27 Navitar Industries, Llc Optical assembly for a wide field of view camera with low TV distortion
US10317652B1 (en) 2014-03-16 2019-06-11 Navitar Industries, Llc Optical assembly for a wide field of view point action camera with low astigmatism
US10386604B1 (en) 2014-03-16 2019-08-20 Navitar Industries, Llc Compact wide field of view digital camera with stray light impact suppression
US10545313B1 (en) 2014-03-16 2020-01-28 Navitar Industries, Llc Optical assembly for a wide field of view point action camera with a low sag aspheric lens element
US10545314B1 (en) 2014-03-16 2020-01-28 Navitar Industries, Llc Optical assembly for a compact wide field of view digital camera with low lateral chromatic aberration
US10739561B1 (en) 2014-03-16 2020-08-11 Navitar Industries, Llc Optical assembly for a compact wide field of view digital camera with high MTF
US10746967B2 (en) 2014-03-16 2020-08-18 Navitar Industries, Llc Optical assembly for a wide field of view point action camera with low field curvature
US11754809B2 (en) 2014-03-16 2023-09-12 Navitar, Inc. Optical assembly for a wide field of view point action camera with low field curvature
CN113050362A (zh) * 2019-12-27 2021-06-29 中芯国际集成电路制造(上海)有限公司 光学邻近修正方法及掩膜版
CN113050362B (zh) * 2019-12-27 2024-04-26 中芯国际集成电路制造(上海)有限公司 光学邻近修正方法及掩膜版

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