WO2015043450A1 - 超分辨成像光刻 - Google Patents

超分辨成像光刻 Download PDF

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Publication number
WO2015043450A1
WO2015043450A1 PCT/CN2014/087182 CN2014087182W WO2015043450A1 WO 2015043450 A1 WO2015043450 A1 WO 2015043450A1 CN 2014087182 W CN2014087182 W CN 2014087182W WO 2015043450 A1 WO2015043450 A1 WO 2015043450A1
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Prior art keywords
illumination
imaging
mask
layer
light field
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PCT/CN2014/087182
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English (en)
French (fr)
Inventor
罗先刚
王长涛
赵泽宇
王彦钦
蒲明薄
姚纳
高平
胡承刚
李雄
黄成�
杨磊磊
刘利芹
王炯
何家玉
罗云飞
刘凯鹏
赵承伟
刘玲
马晓亮
王民
Original Assignee
中国科学院光电技术研究所
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Priority claimed from CN201310438387.4A external-priority patent/CN103454866B/zh
Priority claimed from CN201310439950.XA external-priority patent/CN103472689B/zh
Application filed by 中国科学院光电技术研究所 filed Critical 中国科学院光电技术研究所
Priority to EP14848976.8A priority Critical patent/EP3051351B1/en
Priority to JP2016505702A priority patent/JP6127203B2/ja
Priority to US14/909,734 priority patent/US9958784B2/en
Publication of WO2015043450A1 publication Critical patent/WO2015043450A1/zh

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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
    • G03F7/70325—Resolution enhancement techniques not otherwise provided for, e.g. darkfield imaging, interfering beams, spatial frequency multiplication, nearfield lenses or solid immersion lenses

Definitions

  • the present disclosure relates generally to the field of lithography, and more particularly to a method, device and apparatus for non-contact mode super-resolution imaging optical lithography.
  • optical imaging lithography With the development of optical imaging lithography, Rayleigh resolution limits have become a major obstacle to limiting optical resolution. Due to the limited numerical aperture of the objective imaging system, the linear resolution of optical lithography under single exposure conditions is generally limited to about 1/4 of the illumination wavelength. Super-resolution optical imaging lithography will be of great significance for extended optical lithography resolution and technical vitality, and it is expected to provide low-cost, high-resolution new nano-processing methods for micro-nano-scale scientific research and production.
  • Super lens imaging technology based on surface plasmon effect is a new type of super-resolution optical imaging method that has attracted attention in recent years. It originated from the Perfect Refractive Lens (Pendry JB, Negative Refraction Makes a Perfect Lens. Phys. Rev. Lett. 85, 3966-3969 (2000)) proposed by Professor Pendry of the Imperial University of England.
  • the dielectric constant and magnetic permeability of the perfect lens are both negative, and the evanescent wave component carrying the subwavelength structure information of the object can be amplified, so that all the wave vector components can reach the image plane and participate in imaging without missing.
  • perfect imaging without aberrations and resolution limitations can be achieved. However, there is no such naturally occurring material with a negative refractive index in nature.
  • the surface plasmon wave is excited by the incident light of the transverse magnetic polarization state (TM) (Surface Plasmon) , SP), can produce super-resolution imaging effects on both sides of the metal film.
  • TM transverse magnetic polarization state
  • surface plasmon imaging lithography belongs to the field of near-field lithography.
  • Canon Japan has proposed a near-field nano-optical lithography tool.
  • the deformable SiN film is used as a mask pattern carrier, and the mask pattern is closely contacted with the upper surface of the silicon wafer photoresist by vacuum adsorption to obtain a line width resolution pattern of 32 nm or more.
  • the difficulty of nanolens lithography based on superlens is mainly due to the very short working distance between the mask structure and the lithographic substrate structure (such as silicon wafers, etc.).
  • the allowable working distance is only a few nanometers, which is nearly zero.
  • the existing super-lens-based super-resolution imaging technology adopting a contact mode of lithography in the lithography process, that is, the mask structure is in direct physical contact with the lithographic substrate structure. Obviously, this will cause mask damage.
  • the mask is generally an expensive, precision-machined pattern structure. In order to maintain a certain service life, it is desirable to extend the gap between the mask structure and the lithographic substrate structure as much as possible while ensuring the imaging resolution. Physical contact.
  • the flatness of the small size range (such as within 10 mm) of the device surface can generally be controlled to about 10 nm.
  • the gap between the mask structure and the lithographic substrate structure can be extended to a level of, for example, several tens of nanometers or more to achieve separation between the two, and an important technique for realizing a non-contact imaging optical lithography tool in a non-contact mode can be provided. way.
  • an imaging lithography apparatus can include an illumination light field generating device configured to generate an illumination light field that images a pattern contained in the mask through a mask.
  • the illumination light field may comprise a high frequency spatial spectrum such that the high frequency evanescent portion of the optical field spatial spectral information transmitted through the mask pattern is moved to the low frequency evanescent portion.
  • the illumination light field generating device can be configured to form an illumination light field in accordance with high numerical aperture (NA) illumination and/or surface plasma (SP) wave illumination.
  • NA numerical aperture
  • SP surface plasma
  • a super-resolution imaging lithography method comprises: forming an illumination light field comprising a high frequency spatial spectrum according to an SP wave illumination mode and/or a high NA illumination mode; and illuminating the mask pattern by using the illumination light field to obtain a light field transmitted through the mask pattern, the transmitted light field
  • the high frequency evanescent wave portion of the spatial spectrum information is moved to the low frequency evanescent portion; and the transmitted light field is projected onto the substrate through a certain gap to image the mask pattern on the substrate.
  • high NA and/or SP illumination may be utilized, and the mask pattern-assisted trench structure and the metal-photosensitive layer-metal-assisted imaging lithography structure may be combined to achieve an extended mask base structure and a photolithographic substrate.
  • the gap between the sheet structures, the imaging contrast and the quality of the imaging lithography are improved, and a non-contact method, device structure and device for super-resolution imaging lithography are realized.
  • FIG. 1 is a partial schematic diagram of a super-resolution imaging lithography apparatus in accordance with an embodiment of the present disclosure
  • FIG. 2 is a schematic diagram of a solid or liquid immersion projection illumination structure implementing super-resolution imaging lithography in accordance with an embodiment of the present disclosure
  • 3 is a schematic structural diagram of a prism illumination mode for realizing super-resolution imaging lithography according to an embodiment of the present disclosure, wherein 3(a) is a schematic diagram of a roof prism illumination structure; 3(b) is a schematic diagram of a four-sided pyramid prism illumination structure; 3(c Is a schematic cross-sectional view of an imaging lithography structure;
  • FIG. 4 is a schematic structural diagram of a spectroscopic grating illumination mode implementing super-resolution imaging lithography according to an embodiment of the present disclosure
  • FIG. 5 is a partial schematic diagram of a super-resolution imaging lithography apparatus of an SP wave illumination mode, in accordance with an embodiment of the present disclosure
  • FIG. 6(a) is a schematic diagram showing a structure of a mask pattern for realizing aperiodic, non-dense line graphic imaging lithography according to an embodiment of the present disclosure
  • FIG. 6(b) is a schematic cross-sectional view of an imaging lithography structure
  • NI Normal Illumination
  • NA 0
  • OAI Off axis Illumination
  • FIG. 8 is a 60 nm line width two-dimensional dense line pattern in different illumination modes according to an embodiment of the present disclosure.
  • Fig. 8(b) is the light intensity distribution on the white dotted line in Fig. 8(a) Curve
  • FIG. 8(d) is a light intensity distribution curve on the white dotted line in FIG. 8(c);
  • the gray curve is an optical layer transfer function (OTF) for filtering in an SP wave illumination light field structure.
  • FIG. 12 is a 32 nm linewidth two-dimensional dense line pattern imaging lithography result according to an embodiment of the present disclosure, wherein FIG. 12(a) shows a schematic diagram of a SP wave illumination two-dimensional super-resolution imaging lithography, and FIG. 12(b) shows The imaging simulation results of the photosensitive layer region and the light intensity distribution cross-section curve at the white dotted line are shown in Fig. 12(c), and Fig. 12(d) shows the structure of the contrast super-resolution imaging lithography under normal incidence illumination. The imaging simulation results of the control structure photosensitive layer region and the light intensity distribution cross-sectional curve at the white dotted line are shown;
  • Figure 13 (a) is a super-resolution imaging structure according to an embodiment of the present disclosure, in different illumination modes, the same air gap (40 nm), the imaging contrast simulation result curve of different line width line patterns
  • SPI Surface Plasmon Illumination
  • NI Normal Illumination
  • FIG. 14 is a result of imaging light field simulation in a photoresist after off-axis illumination and introduction of a trench structure in accordance with an embodiment of the present disclosure, wherein FIG. 14(a) shows the off-axis illumination of the photosensitive layer region. And the image field distribution after the introduction of the trench structure, Figure 14 (b) shows the contrast structure (normal incidence illumination And the grooved structure of the imaging light field distribution, Figure 14 (c) is a comparison of the light intensity distribution cross-section curve on the white dotted line in Figures 14 (a) and 14 (b), 14 (d) for different air gaps The photosensitive layer area is imaged by a width curve.
  • the reason why the conventional near-field optical lithography and super-lens imaging lithography cannot realize the gap separation lithography is mainly that in the interstitial spaces such as air and liquid, the evanescent wave carrying the sub-wavelength pattern information of the mask is sharply attenuated after leaving the surface of the hyper-lens.
  • the reduction of the intensity of the high-frequency information leads to a rapid decline in imaging resolution and lithography contrast, and effective imaging lithography cannot be achieved.
  • the spatial spectral distribution of the transmitted light field of the mask pattern can be adjusted according to the graphic line width dimension and the graphic structure of the super-resolution imaging lithography, and the high NA off-axis illumination and/or the surface plasmon wave illumination mode are selected.
  • the high-frequency information of the mask pattern is moved from the high-frequency evanescent wave to the low-frequency evanescent wave portion, thereby reducing the attenuation amplitude of the sub-wavelength pattern evanescent wave information in the super-resolution imaging process, and realizing long working-space gap imaging lithography.
  • SP wave illumination is used to adjust the transverse wave vector of the SP wave illumination field to cause spatial frequency shift of the transmitted light field of the grating mask, resulting in only +1 level (and / or -1 level) and 0 level
  • the diffracted light is coupled to the imaging space to coherently superimpose, and the imaging contrast can be improved by reducing the specific gravity of the zero-frequency wave vector component in the spectral space.
  • the ratio of the longitudinal electrical polarization component to the transverse polarization component in the imaging space region can be suppressed, thereby reducing the negative influence of the longitudinal electric field component of the imaging light field on the imaging quality, and realizing Further improve the imaging contrast.
  • These two mechanisms can advantageously work together to achieve the extension of the gap between the mask pattern structure and the lithographic substrate structure, and solve the resolution in near-field optical lithography.
  • the problem of falling and short working distance is to achieve a super-resolution imaging lithography effect in which the mask pattern layer and the lithographic substrate are separated by a gap, and a high contrast imaging lithography pattern is obtained.
  • gap separation super-resolution imaging lithography lithography efficiency, mask wear reduction and mask lifetime can be effectively improved, and high-precision optical lithography alignment and splicing can be realized.
  • a super-resolution imaging lithography apparatus may include an illumination system 101, a mask substrate 102, a surface plasmon (SP) wave illumination light field excitation structure 103, a mask structure 104, and photolithography.
  • Substrate structure 105 An air, vacuum or liquid barrier layer, for example between 20 nm and 200 nm, may be present between the lower surface of the mask structure 104 and the upper surface of the lithographic substrate structure 105.
  • Physical isolation between the mask structure 104 and the lithographic substrate structure 105 facilitates mask pattern protection.
  • the specific composition and structure of each of the illumination system 101, the mask structure 104, and the lithographic substrate structure 105, the thickness of the isolation layer, and the like can be selected according to the line width, dimensions, and achievable convenience of the lithographic pattern.
  • Illumination system 101 can include a light source, a homogenizing module, and a high numerical aperture (eg, 0 ⁇ NA ⁇ 1.8) illumination light field shaping optical structure.
  • the numerical aperture of the illumination field is defined as the product of the sine of the angle between the chief ray of the illumination field and the normal of the illumination surface and the refractive index of the illumination space.
  • the illumination light field shaping optical structure can be selected but is not limited to: solid or liquid immersion projection illumination structures (as shown in Figure 2), solid prism illumination with high refractive index materials. Structure (as shown in Figure 3), or a spectroscopic grating illumination structure (as shown in Figure 4).
  • the intensity non-uniform light field 202 emitted by the light source 201 can be uniformly distributed by the homogenizing module 203.
  • the beam shaping element 204 can be used to shape the normal incidence illumination field into a far field bipolar, quadrupole or ring illumination.
  • the illumination chief ray angle is assumed to be ⁇ 1 ⁇ ⁇ , and ⁇ is the desired illumination aperture angle.
  • the projection illumination optical system 205 having a magnification of M times can be further adopted (205 in FIG.
  • the image side of the optical system 205 can select a liquid immersion or solid immersion mode to illuminate the chief ray.
  • FIG. 3 illustrates a solid prism illumination structure of a high refractive index material in accordance with an embodiment of the present disclosure.
  • the homogenized illumination beams 302, 304 can be divided into two or four beams, which are symmetrically incident into the prism from the two sides or four sides of the prisms 301, 303, respectively, so that the bottom surface of the prism can be generated as in formula (1).
  • prism The form may be a four-sided pyramid prism 303.
  • the direction of the mask pattern line is substantially perpendicular to the direction of the illumination light.
  • the material selection of the prisms 301, 303 can be determined based on the wavelength ⁇ 0 of the illumination beam. For example, a high refractive index transparent glass material at a wavelength of the illumination beam may be selected.
  • the prism material may include, but not limited to, materials such as ultraviolet light-transmitting sapphire glass, fused silica glass, and the like.
  • FIG. 4 shows a schematic diagram of a spectroscopic grating illumination structure in accordance with an embodiment of the present disclosure.
  • a one- or two-dimensional beam splitting grating 402 and a filter film layer structure 403 can be loaded over the mask substrate 102 to achieve a high angle off-axis illumination light field at a particular angle.
  • the direction in which the spectral grating 402 is arranged may be substantially the same as the direction in which the mask line pattern is arranged.
  • the selection of the period of the spectral grating 402 can make the +1, -1 order diffraction satisfy the requirement of the formula (1), that is,
  • d_grating is the period of the spectral grating 402
  • n is the refractive index of the mask base material
  • ⁇ is the angle between the chief ray of the illumination light field (for example, +1, -1 order diffracted ray) and the normal line in the base material
  • ⁇ 0 is the light source vacuum wavelength.
  • the spectral grating 402 can be introduced into a single or a plurality of FP cavities 403 composed of a multilayer film of a metal 4031 and a medium 4032, which satisfies resonance conditions for +1 and -1 order diffracted light. Efficient transmission, while the transmittance for other orders is approximately zero.
  • the thickness of the mask substrate 102 can be much larger than the interference length of the light source.
  • the coherence of the light field not only introduces coherent noise, affects uniformity, but also causes non-uniformity due to internal interference of the patterned imaging light field.
  • the coherence of the light field can basically meet the requirements, but it is not excluded that the design special structure is further reduced. Partial coherence of the light field.
  • a high uniform illumination intensity distribution of the same illumination pattern such as a light intensity fluctuation of less than 3%, over substantially all of the mask pattern illumination area.
  • Technology in the field The surgeon can envisage a variety of uniform illumination methods, which are not described here. However, for some mask patterns, such as micron-scale graphics, different line width nano-patterns coexisting, from the technical achievability, it can be considered to select different illumination modes of illumination light fields in micro-patterns and different line width nano-pattern areas. .
  • a variety of specific implementation methods can be conceived by those skilled in the art, and details are not described herein again.
  • the illumination light field polarization may be selected to be a natural polarization mode for compatibility with general mask pattern structures.
  • a polarizing device can be added to the illumination light path to realize that the polarization direction of the electric field is substantially perpendicular to the line direction, and the contrast of the super-resolution imaging light field can be improved to some extent to improve the lithography effect.
  • a specific implementation method can be conceived by those skilled in the art, and details are not described herein again.
  • the illumination light field may have a certain range of divergence angles, and the divergence angle may be within a range of ⁇ 10°.
  • the wavelength of the light source may be selected to match the wavelength of the photosensitive layer material, including but not limited to a mercury lamp g-line, an i-line, a 193 nm wavelength ArF, a 157 nm wavelength KrF light source, and the like.
  • FIG. 5 is a partial schematic diagram of a super-resolution imaging lithography apparatus of an SP illumination mode in accordance with an embodiment of the present disclosure.
  • the mask substrate 501 can be secured to the underside of the solid immersion projection illumination system 205 by an index matching fluid or adhesive (see Figure 2). Or the bottom surface of the prism 301 or 303 (see Fig. 3).
  • the mask substrate 501 can be approximately the same as the material refractive index of the prisms 301, 303 and the solid immersion lens 205.
  • the SP wave illumination light field excitation structure 103 may be located below the mask substrate 501 above the mask pattern layer 503.
  • the structure 103 may include an excitation layer structure 5021, a coupling layer 5022, and a multi-layer filter layer composed of a plurality of layers of a metal layer 5023 and a dielectric layer 5024. For convenience of description, only 3 is shown in FIG. Pair of metal layer 5023 and dielectric layer 5024).
  • the excitation layer structure 5021 can be a nanostructure layer prepared on a mask substrate.
  • the excitation layer structure can receive the far field illumination beam 513 to efficiently excite SP waves of a particular transmission wavelength.
  • the nanostructured pattern in the excitation layer 5021 can be a one-dimensional or two-dimensional pattern, such as a grating structure of a particular period.
  • the far-field illumination light in different directions excites the SP waves transmitted in the corresponding direction surface.
  • the coupling layer 5022 assists in the efficient coupling of the SP waves into the clutter filter layer.
  • the coupling layer 5022 may include, but is not limited to, a high refractive index dielectric film layer material such as TiO 2 .
  • Clutter filter layer may comprise alternating metal and dielectric multilayer film structure, each layer may have a thickness on the order of nanometers, including but not limited to a multilayer film structure of the metal Al and MgF 2 dielectric layers are alternately stacked.
  • the clutter filter layer can reduce the stray light field interference of the excitation layer structure 5021 to excite the SP process to generate other levels, and form a substantially uniform SP wave illumination field on the upper surface of the mask pattern layer 503.
  • the mask structure 104 may include a mask pattern layer 503, a filling layer 504, an imaging film layer 505, a protective film layer 506, and a gap pad film layer 507 from an illumination example.
  • the fill layer 504 under the mask layer 503 can include a dielectric material including, but not limited to, PMMA (polymethylmethacrylate) or the like.
  • the imaging layer 505 may be selected as a metal film layer, and the absolute value of the real part of the dielectric constant may be different from the real part of the dielectric constant of the filling layer 504.
  • Imaging layer 505 can include, but is not limited to, Ag, Au, Al, and the like.
  • the imaging metal film layer may include Ag.
  • the imaging metal film layer can include Al.
  • the protective layer 506 can prevent physical and chemical corrosion of the imaging layer and the pattern layer in the mask structure.
  • the protective layer may have a thickness of 5-10 nm, and the material may include, but is not limited to, a dense film layer such as SiO 2 or diamond.
  • the gap pad film layer 507 can form a fixed-size gap in the exposure pattern region in the gap passive control mode.
  • the SP wave illumination light field excitation structure 502 and the mask pattern layer above the mask pattern layer 503 may be selectively removed.
  • the lithographic substrate structure 105 may include an auxiliary imaging film layer 509, a photosensitive layer 510, and a reflective layer 511 from the illumination example, and the three are stacked on the lithographic substrate 512.
  • the auxiliary imaging film layer 509, the photosensitive layer 510, and the reflective layer 511 constitute an SP resonant cavity imaging structure, and the reflective layer 511 can be used to modulate the specific gravity of the imaging electric field component inside the photosensitive layer to improve the imaging lithography contrast.
  • the auxiliary imaging film layer 509 over the photoresist can be removed, taking into account the convenience of subsequent lithography processes, although this can result in some degradation of imaging lithography performance.
  • the auxiliary imaging layer 509 above the photosensitive layer and the lower reflective layer 511 may include a metal material exhibiting a negative dielectric constant in a wavelength range of the light source, and a dielectric constant real part size may be different from a dielectric constant of the filling layer 504 and the photosensitive layer 510.
  • the real parts are not much different, including but not limited to Ag, Au, Al, etc.
  • the auxiliary imaging film layer may include Ag for a central wavelength of the mercury light i-ray source at 365 nm.
  • the auxiliary imaging film layer may comprise Al.
  • the illumination field passes through the mask pattern layer 503, the fill layer 504, the imaging layer 505 and the protective layer 506, the vacuum, air or liquid isolation layer 508, the auxiliary imaging film layer 509, and the pattern in the mask structure is imaged on the lithographic substrate structure.
  • the photosensitive layer 510 is in the space.
  • the nano-pattern layer 503 in the mask pattern layer may be a one-dimensional or two-dimensional pattern, and the nano-pattern line arrangement direction may be substantially consistent with the excitation layer nano-pattern line arrangement direction or the off-axis illumination direction.
  • High NA off-axis illumination or surface plasmon illumination can be selected based on the graphical line width dimension and graphical structure of the super-resolution imaging lithography.
  • one-dimensional, two-dimensional prism off-axis illumination, immersion projection objective illumination, or grating spectroscopic illumination with high numerical aperture may be selected.
  • n sin( ⁇ ) is the numerical aperture of the illumination field.
  • the formula (2) does not need to be strictly satisfied, and an error of, for example, +/- 20% is allowed, although this brings about a certain decline in imaging lithography performance.
  • n ⁇ sin ( ⁇ ) located 0.8 ⁇ 0 /(2d) ⁇ 1.2 ⁇ 0 / (2d) range interval.
  • a solid or liquid immersion projection illumination structure (as shown in Figure 2) or a solid prism illumination structure with a high refractive index can be used (as shown in Figure 3). ), or a spectroscopic grating illumination structure (as shown in Figure 4).
  • the above rules for selecting the illumination structure according to the line width of the super-resolution lithography pattern are not strictly Standard. If the gap is small, even a linewidth pattern below 1/6 wavelength can use high NA off-axis illumination to improve imaging contrast and lithography quality.
  • the SP wave illumination light field excitation structure 103 can be introduced over the mask pattern layer on the basis of the illumination described above.
  • SP wave illumination it can be equivalent to light field illumination with higher numerical aperture. Adjusting the transverse wave vector of the SP wave illumination field causes the spatial frequency shift of the diffracted light of the mask structure pattern, -1 (or +1) level and 0 The graded diffracted light can be coupled into the transmission spectrum of the imaging system to interfere, thereby increasing contrast.
  • the SP wave illumination field carries the graphic light field information through the illumination mask pattern, and further images the pattern in the mask structure through the filling layer 504, the imaging layer 505 and the protective layer 506, the air or liquid isolation layer 508, and the auxiliary imaging layer 509. The area of the photosensitive layer 510 in the lithographic substrate structure.
  • the SP wave illumination light field excitation structure 103, the illumination light, and the mask pattern can satisfy the following equations (3) and (4),
  • d represents the period of the dense line pattern of the mask
  • d s represents the grating period of the excitation layer 5021
  • the center wavelength is ⁇ 0
  • the incident angle of the center light of the illumination light field in the mask base material is ⁇
  • n is the mask base
  • ⁇ 0 is the center wavelength of the far-field illumination beam
  • ⁇ sp is the wavelength of the excited SP wave.
  • the generation of the far field illumination beam 513 may utilize, but is not limited to, one of the high NA illumination structures described above, as shown in Figures 2, 3 and 4.
  • the mask pattern layer to be a non-periodic, discrete form of nano-pattern, based on the above method, the mask pattern structure can be further improved, and a better imaging lithography can be obtained in the case of a large gap. effect.
  • one or two groove structures 603 may be symmetrically added on both sides of the edge of the transparent line pattern 602.
  • the mask line slit pattern 602 transmits the evanescent wave carrying the high frequency spatial information in the light field, scattering and Converging to the imaging layer
  • the width of the trench 603 may be about 1/3 to 1/7 of the source vacuum wavelength, and the depth may be about 1/5 to 1/7 of the source vacuum wavelength.
  • the center of the trench may be about 1/1 of the center of the mask line. 2 to 1/5 light source vacuum wavelength.
  • the high-resolution aperture illumination mode suitable for the super-resolution imaging lithography and the lithography pattern line width index can be selected to reach the evanescent wave and surface plasmon wave categories.
  • the illumination generation method is different from the conventional projection lithography objective off-axis illumination, such as a high refractive index prism illumination structure, an SP excitation and a clutter filter film layer structure, and the like.
  • a super-resolution imaging lithography apparatus can include an illumination source, an illumination system, an imaging lithography module, an imaging gap monitoring module, a workpiece stage system, an alignment optics system, a control system.
  • the illumination system 101 can include a projection illumination module that implements illumination of two poles, four poles or ring beam shaping, a prism illumination module, a spectroscopic grating illumination module, and the like.
  • the imaging lithography module may include the above-described mask structure 104, lithographic substrate structure 105, and associated assembly control mechanisms and the like.
  • the imaging gap monitoring module can monitor the gap between the lower surface of the mask structure 104 and the upper surface of the lithographic substrate structure 105 in real time, including but not limited to using an FTP test module, a white light interferometer test module, a capacitance displacement sensor, and the like.
  • the alignment optics can be precisely aligned with the mark coarse alignment and the moire fringes.
  • the control system can control the gap between the mask structure 104 and the lithographic substrate structure 105 in a passively controlled and/or actively controlled manner.
  • the mask substrate is precision machined and has a highly flat surface.
  • a gap spacer spacer layer may be introduced on the lower surface of the mask structure to form a window structure including a pattern region, and the window height is a lithography gap height.
  • the workpiece table system has an adaptive leveling structure such as a flexible hinge.
  • Passive control can be performed, for example, as follows.
  • the illumination structure and parameters can be selected based on the line width and type of the lithographic pattern.
  • Moving the mask structure 104 a lower surface of the mask structure 104 having a gap spacer layer is achieved in proximity to the lithographic substrate structure 105.
  • the average gap is controlled, for example, at a level of about 1 ⁇ m to 10 ⁇ m. Alignment is achieved by aligning the optical system, moving and rotating the stage. Continuing to move the mask structure 104 having the gap spacer layer, the gap window structure film layer is made to have a large area and uniform contact with the upper surface of the photolithography substrate structure 105.
  • a thin mask substrate or a thin lithographic substrate may be used, including but not limited to a fused silica plate having a thickness of 0.1 mm to 0.5 mm, etc., and the gas pressure above the mask substrate is increased to realize a mask having a gap spacer layer.
  • the lower surface of the mold structure 104 is in contact with the upper surface of the photolithographic substrate structure 105 in a large area.
  • the mask structure 104 always maintains a fixed air or liquid gap with the upper surface of the lithographic substrate structure 105 due to the presence of the window structure film layer. Thereby mask pattern damage is avoided.
  • Active control can be performed, for example, as follows.
  • the flatness of the lower surface of the mask structure 104 and the upper surface of the photolithographic substrate structure 105 is precisely controlled to be in the range of about 10 nm.
  • the gap detection module is combined with the leveling and displacement mechanism of the workpiece table system to control the average value of the gap of the exposed pattern region to a level of, for example, about 20 nm to 200 nm according to the needs of the imaging lithography design.
  • the center wavelength of the light source is 365 nm of the mercury lamp i-line.
  • the illumination structure includes a sapphire roof prism (one-dimensional lithography pattern) 301 or a four-sided cone sapphire prism (two-dimensional lithography pattern) 303 in FIG. 3 (a, b).
  • the mask substrate light incident surface is placed in close contact with the prism light exit surface, for example, by a refractive index matching liquid or an adhesive to fix the mask substrate to the light exit surface of the prism.
  • a sapphire mask substrate 305 As shown in FIG. 3(c), a sapphire mask substrate 305, a metal chrome mask pattern layer 306, a 10 nm thick PMMA mask pattern fill layer 307, a 20 nm thick metal silver image film layer 308, and a 50 nm metal chrome-gap spacer are used.
  • the mercury lamp i-line source with a center wavelength of 365 nm, is homogenized and split into two beams of light 302 or 304, illuminating from both sides of the prism to the surface of the mask pattern in a symmetrical manner.
  • the illumination chief ray has an illumination angle of 60° in the prism.
  • the prism has a refractive index of 1.8.
  • the corresponding illumination numerical aperture is 1.5.
  • the lithographic substrate structure 105 includes a 20 nm thick upper auxiliary imaging silver film 311, a 30 nm thick photoresist photosensitive layer 312, a 50 nm thick silver film reflective layer 313, and a 1 mm thick fused silica substrate 314 from top to bottom.
  • the lower surface of the mask structure is in close contact with the upper surface of the photolithographic substrate structure. Due to the existence of the spacer spacer layer 310, an air gap of 50 nm thickness is formed, which effectively protects the mask pattern layer structure.
  • An off-axis illumination field with an NA of 1.5 in the prism is used to image the mask nanopattern into the photosensitive layer on the fused silica substrate through a mask. Imaging lithography of the nano line pattern is achieved by exposing, removing the auxiliary imaged silver film on the photoresist, developing, and the like.
  • the line width is 60 nm
  • the mask depth is 50 nm
  • the period is 120 nm
  • the duty ratio is 1:1
  • the air gap thickness is 50 nm.
  • the imaging light field results in this example were simulated using numerical simulation.
  • the dielectric constants of Cr, Ag, and photosensitive layers were -8.55+8.96i, -2.4012+0.2488i, and 2.59, respectively.
  • the simulation imaging results are shown in Fig. 7.
  • Fig. 7c shows the two illumination modes.
  • the imaging light field intercept intensity distribution has an imaging contrast of 0.25 and 0.83, respectively.
  • NA 1.5.
  • Figure 8 shows the results of a dense graphical simulation of a 60 nm linewidth two-dimensional line.
  • the mask pattern layer has a line width of 60 nm and a center-to-center distance between adjacent lines of 120 nm.
  • the air gap is set to 50 nm.
  • the illumination beam is homogenized, it is divided into four beams, which are symmetrically illuminated on the surface of the mask pattern from the four sides of the tetrahedral sapphire prism 303 at an incident angle of 60° inside the prism material, and the azimuth angles are 0° and 90, respectively. °, 180° and 270°.
  • the contrast ratio is 0.7.
  • Fig. 8(d) shows the intensity distribution of the image field line corresponding to Fig. 8(c) with a contrast ratio of 0.07.
  • the simulation results show that the high numerical aperture illumination field can improve the contrast and lithography resolution of near-field imaging patterns.
  • the SP-wave illumination is used, and the line width pattern is a dense line pattern of 32 nm and a period of 64 nm.
  • the mercury lamp i-line source used has a wavelength of 365 nm.
  • the optimal SP illumination field equivalent numerical aperture required is 2.8.
  • this embodiment designs an SP illumination light field structure with an equivalent numerical aperture of 2.5.
  • the substrate 501 is fused silica.
  • the chief ray incident angle of the two far-field illumination light fields 513 which are incoherent with each other is ⁇ 28° (the angle between the chief ray and the normal in the fused silica base material), and the SP excitation layer 5021 has a grating period of 200 nm.
  • the depth is 40nm and the duty ratio is 1:1.
  • excitation grating is a one-dimensional structure, the direction is substantially consistent with the direction of the lithography mask line.
  • the grating excitation layer 5021 can receive the far field illumination beam 513 to efficiently excite an SP wave illumination field of a particular transmission wavelength.
  • the SP excitation layer lower coupling layer 5022 is a 75 nm thick TiO 2 film layer, and a multilayer film structure formed by alternately stacking 5 pairs of 15 nm thick metal Al film and 15 nm thick dielectric MgF 2 film layer material is used as the SP clutter filter layer.
  • the dielectric constants for SiO 2 , TiO 2 , MgF 2 , and Al were 2.13, 14.91 + 1.94i, 1.932, -19.4238 + 3.6028i, respectively.
  • the numerical simulation of Fig. 10 shows that the hybrid filter layer of MgF 2 /Al has a good filtering effect.
  • the gray curve in Fig. 10 shows the OTF curve of five pairs of MgF 2 /Al alternating dielectric metal multilayer films (k x represents the transverse wave vector of the illumination field), and the light transmission window spatial wave vector of the multilayer film is 1.5. k 0 to 3k 0 (k 0 represents a vacuum wave vector).
  • the far field illumination light illuminates the SP excitation layer 5021 grating, producing an SP wave illumination field 514 having a lateral wave vector of 2.5 k 0 .
  • the transmittance of the spatial spectrum of the illumination field is as shown in the black histogram distribution in Fig. 10. From Fig. 10, it can be seen that the intensity of the illumination field is concentrated on the spatial spectrum of 2.5 k 0 , and the transmittance of other frequencies is effectively suppressed.
  • the mask pattern layer 504 is placed directly on the illumination field generating structure (in this example, placed at the bottom of the SP excitation structure 502).
  • the SP wave illumination light field acts on the mask pattern, and in the presence of an air gap, the contrast of the imaging light field in the photosensitive layer can be greatly improved.
  • the line width is 32 nm, the period is 64 nm, and the duty ratio is 1:1.
  • a mask pattern can be formed by a patterned metal material such as Cr, and the Cr layer has a thickness of, for example, 40 nm.
  • the mask pattern is set as an air gap below.
  • the photosensitive layer 510 is a photoresist and has a thickness of 30 nm.
  • Substrate 512 can include, for example, 1 mm thick quartz.
  • an example of an illumination field is an Ag layer having a thickness of 15 nm for the auxiliary imaging layer.
  • imaging layer 509 is disposed on the mask fill layer.
  • An example of the illumination field facing the photosensitive layer 510 is a 70 nm thick metal silver reflective layer 511. The three are laminated on a quartz substrate 512.
  • the optical field distribution in the photoresist in this example was simulated by numerical simulation.
  • the dielectric constants of Cr, Ag, and photosensitive layers were -8.57+8.66i, -2.4012+0.2488i, and 2.59, respectively.
  • the simulation imaging results for the one-dimensional dense line pattern are shown in Fig. 11, wherein Fig. 11(b) is an enlargement of the white dotted line area in Fig. 11(a).
  • Fig. 11(c) is an enlargement of the white dotted line area in Fig. 11(a).
  • the structure of the excitation layer 5021 depends on the specific pattern of the mask pattern layer 503.
  • the pattern of the excitation layer 5021 may also be a two-dimensional pattern.
  • the specific simulation conditions are as follows: the excitation layer pattern is a square hole array grating structure, the hole side length is 100 nm, the hole center spacing is 200 nm; the pattern layer is a two-dimensional fold line, the fold line angle is 90°, the fold line line width is 32 nm, the period is 64 nm; the incident light For four incoherent illuminations with a center wavelength of 365 nm, the angle of incidence is 28° and the azimuth angles are 0°, 90°, 180° and 270°, respectively.
  • FIG. 12(a) is a schematic diagram of a surface plasma wave illumination imaging lithography
  • FIG. 12(c) is a schematic diagram of normal incidence illumination lithography
  • FIGS. 12(b) and 12(d) respectively show The simulation results in these two modes, the illustrations in Figures 12(b) and 12(d) are the intensity distributions on the corresponding white dashed lines.
  • the simulation results show that the nano-imaging lithography structure can be improved by surface plasma wave illumination, which can improve the contrast and resolution of super-resolution imaging lithography.
  • FIG. 13 is a SPI (Surface Plasmon Illumination) illumination mode and an NI (Normal Illumination) illumination mode contrast curve of different line width patterns in the SP wave light field transverse wave vector of 2.5 k 0 and 40 nm thickness air gap in this embodiment (FIG. 13).
  • (a)) and the contrast curve of the 32 nm linewidth dense line pattern at different air gaps (Fig. 13(b)). It can be seen from Fig. 13(a) that the structure maintains high contrast imaging for dense line patterns of different line widths above 32 nm under the conditions of fixed surface plasma wave illumination parameters and 40 nm air gap.
  • the image intensity contrast in the photosensitive layer is greater than 0.4 as the criterion, the air gap can be extended to 60 nm.
  • the imaging lithography with normal incidence illumination has an air gap of only about 10 nm.
  • the present disclosure proposes a super-resolution imaging optical lithography method that is also effective for discrete nano-line patterns.
  • An example of super-resolution imaging lithography of a 60 nm line width isolated line mask pattern is presented herein.
  • two sets of metal trench structures 603 are symmetrically introduced on both sides of the exit surface of the line gap 602 of the 60 nm line width chrome mask pattern.
  • the center of the trench is 110 nm from the center of the slit, the groove width is 55 nm, the groove depth is 45 nm, and the mask pattern layer 601 has a chromium film thickness of 90 nm.
  • the air gap 604 is set to 100 nm.
  • the lithographic substrate structure 105 is configured as a 20 nm thick metal silver imaging film layer 605, a 30 nm thick photoresist 606, and a 70 nm metallic silver reflective layer 607, and a 0.3 mm thick silicon wafer 608.
  • Figure 14 shows the results of the imaging simulation.
  • Fig. 14(a) shows the imaging light field distribution after the off-axis illumination and the introduction of the trench structure in the photosensitive layer region
  • Fig. 14(b) shows the imaging light field distribution of the contrast structure (normal incidence illumination and non-trench structure)
  • 14 (c) ) is a cross-sectional curve along the white dashed line in FIGS. 14(a) and 14(b)
  • FIG. 14(d) is the line pattern width in the photoresist under different air gaps. It can be seen that the line width of the pattern is significantly suppressed, especially for the case where the air gap is larger than 100 nm, and the image line width is compressed from 300 nm to about 80 nm.
  • the lithography imaging process may be as follows.
  • the illumination mode can be selected for the lithographic pattern line width.
  • a high NA off-axis illumination method is selected for a linewidth pattern below 1/6 wavelength.
  • uniform illumination is achieved at a center wavelength of ⁇ 0 and a specific far-field illumination beam direction (the incident light center direction is at an angle ⁇ to the main optical axis such as the device surface normal).
  • the excitation layer in the mask structure excites SP waves of a specific transmission wavelength.
  • the spurious filter layer can be used to increase the SP wave transmission intensity.
  • the SP wave illumination field or the high NA off-axis illumination light field can be coupled to the pattern layer in the mask structure to transport the imaging layer in the mask structure.
  • the imaging light field carrying the pattern layer penetrates the air or liquid spacer layer under the action of the auxiliary imaging layer in the lithographic substrate structure, and The coupling is transferred into a photosensitive layer in the lithographic substrate structure.
  • Super-resolution imaging lithography is achieved in the photosensitive layer by photolithography processes such as exposure, removal of an auxiliary imaging layer, and development.

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  • Physics & Mathematics (AREA)
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  • Preparing Plates And Mask In Photomechanical Process (AREA)

Abstract

一种超分辨成像光刻设备，其中包括照明光场产生装置。照明光场产生装置产生的照明光场通过掩模（104）并对掩模（104）中包含的图形进行成像。照明光谱包含高频空间频谱，使得透射通过掩模图形的光场空间频谱信息的高频倏逝波部分移动到低频倏逝波部分。照明光场产生装置可以被配置为按照高数值孔径照明和/或表面等离子体波照明方式来形成照明光场。还公开了一种超分辨成像光刻方法。

Description

超分辨成像光刻 技术领域
本公开一般地涉及光刻技术领域，更具体地，涉及一种非接触方式的超分辨成像光学光刻的方法、器件和设备。
背景技术
随着光学成像光刻技术发展，瑞利分辨极限成为限制光学分辨力的主要障碍。由于物镜成像系统数值孔径有限，单次曝光条件下光学光刻线宽分辨力一般受限于1/4照明波长左右。超分辨光学成像光刻，将对延伸光学光刻分辨力、技术生命力具有重要意义，同时有望为微纳尺度科研、生产领域提供低成本、高分辨力的新型纳米加工手段。
基于表面等离子体效应的超透镜(Super lens)成像技术，是近年来受关注的一种新型超分辨光学成像方法。它起源于英国帝国大学Pendry教授提出的负折射率完美透镜(Perfect lens)(Pendry JB，Negative Refraction Makes a Perfect Lens.Phys.Rev.Lett.85，3966-3969(2000))。完美透镜的介电常数和磁导率同时为负值，能够将携带有物体亚波长结构信息的倏逝波分量进行放大，这样所有的波矢分量都能到达像面参与成像而没有缺失，从而理论上可以实现没有像差和分辨率限制的完美成像。然而，自然界中并没有这种天然存在的具有负折射率的材料，利用具有负介电常数的金属薄膜，在横磁偏振态(TM)的入射光作用下，激发表面等离子体波(Surface Plasmon，SP)，可以在金属薄膜两侧产生超分辨成像效果。
2005年，美国加州伯克力大学利用汞灯i线光源(波长365nm)正入射照明，在50nm厚度铬掩模层纳米图形上制备40nm厚PMMA(polymethylmethacrylate)介质层、35nm厚金属银膜和光刻胶感光层，得到了约60nm左右的半周期分辨力的光刻结果(Fang N，Lee H，Sun C，Zhang X，Sub-diffraction-limited optical imaging with a silver superlens.Science 308：534-537.(2005))。
另一方面，利用表面等离子体的局域增强效应和短波长干涉效应，也可以 实现纳米光学光刻。
物理本质上，表面等离子体成像光刻属于近场光刻范畴。日本佳能公司提出了近场纳米光学光刻工具。采用可变形的SiN薄膜作为掩模图形载体，利用真空吸附的方式，实现掩模图形与硅片光刻胶上表面紧密接触，获得32nm以上线宽分辨力图形。基于超透镜的纳米光学光刻技术面临的困难主要在于，掩模结构与光刻基片结构(如硅片等)之间的工作距非常短。例如，对于利用超透镜实现50nm以下线宽分辨力的超分辨成像技术，能够允许的工作距只有几纳米左右，近乎为零。这导致现有基于超透镜的超分辨成像技术在光刻过程中都采用接触方式的光刻模式，即掩模结构与光刻基片结构是直接物理接触的。显然，这样会造成掩模损伤。众所周知，掩模一般是昂贵的、精密加工的图形结构，为了保持一定使用寿命，希望在保证成像分辨力前提下尽可能延伸掩模结构与光刻基片结构之间的间隙大小，避免两者的物理接触。考虑到当前高精度的光学平面加工水平，针对器件表面的小尺寸范围(如口径10mm以内)平面度一般可以控制在10nm左右。为此，可以将掩模结构与光刻基片结构之间的间隙延伸到例如几十纳米以上水平，实现两者的分离，将为实现非接触模式的超分辨成像光学光刻工具提供重要技术途径。为此，需要设计新颖的超分辨成像光刻结构，以在大工作距的情形下提高成像光刻分辨力、成像光场对比度、焦深。
发明内容
本公开的目的至少部分地在于提供一种可以实现非接触方式的超分辨成像光刻的方法和设备。
根据本公开的实施例，提供了一种成像光刻设备。一示例设备可以包括照明光场产生装置，配置为产生通过掩模对掩模中包含的图形进行成像的照明光场。照明光场可以包含高频空间频谱，使得透射通过掩模图形的光场空间频谱信息的高频倏逝波部分移动到低频倏逝波部分。例如，照明光场产生装置可以被配置为按照高数值孔径(NA)照明和/或表面等离子体(SP)波照明方式，来形成照明光场。
根据本公开的其他实施例，提供了一种超分辨成像光刻方法。该方法可以 包括：按照SP波照明方式和/或高NA照明方式，形成包含高频空间频谱的照明光场；利用照明光场，照射掩模图形，得到透射通过掩模图形的光场，该透射光场空间频谱信息的高频倏逝波部分移动到低频倏逝波部分；以及透射光场经一定的间隙，投射到基片上，以将掩模图形成像在基片上。
根据本公开的实施例，可以利用高NA和/或SP照明，并可以结合掩模图形辅助沟槽结构和金属-感光层-金属辅助成像光刻结构，达到延伸掩模基底结构与光刻基片结构之间间隙，提高成像对比度和成像光刻质量，实现一种非接触方式的超分辨成像光刻的方法、器件结构和设备。
附图说明
通过以下参照附图对本公开实施例的描述，本公开的上述以及其他目的、特征和优点将更为清楚，在附图中：
图1是根据本公开实施例的超分辨成像光刻设备的部分示意图；
图2是根据本公开实施例的实现超分辨成像光刻的固体或液体浸没投影照明结构的示意图；
图3是根据本公开实施例的实现超分辨成像光刻的棱镜照明方式结构示意图，其中3(a)是屋脊棱镜照明结构示意图；3(b)是四面锥形棱镜照明结构示意图；3(c)是成像光刻结构截面示意图；
图4是根据本公开实施例的实现超分辨成像光刻的分光光栅照明方式结构示意图；
图5是根据本公开实施例的SP波照明方式的超分辨成像光刻设备的部分示意图；
图6(a)是根据本公开实施例的实现非周期、非密集线条图形成像光刻的掩模图形结构示意图，图6(b)是成像光刻结构截面示意图；
图7是根据本公开实施例的60nm线宽一维密集线条图形在不同照明方式下的成像光刻模拟结果和对比结果，其中NI(Normal Illumination)为正入射照明，对应的数值孔径NA＝0，OAI(Off axis Illumination)为离轴照明，对应的数值孔径NA＝1.5；
图8是根据本公开实施例的60nm线宽二维密集线条图形在不同照明方式 下的成像光刻模拟结果，其中图8(a)是NA＝1.5的离轴照明情况下的成像光刻模拟结构，图8(b)是图8(a)中白色虚线上的光强分布曲线，图8(c)是NA＝0的正入射情况下的成像光刻模拟结构，图8(d)是图8(c)中白色虚线上的光强分布曲线；
图9是根据本公开实施例的60nm线宽密集线条图形在不同照明方式下的成像光刻实验对比结果；
图10是根据本公开实施例针对32nm线宽设计的SP波照明结构激发的光场空间频谱振幅分布，灰色曲线为激发SP波照明光场结构中起滤波作用的膜层光学传递函数(OTF)曲线；
图11是根据本公开实施例的32nm线宽一维密集线条图形成像光刻结果和不同照明模式下成像空间光强分布曲线对比图，其中图11(a)示出了SP波照明模式下的模拟光场截面，图11(b)示出了图11(a)中白色方框内的感光层区域的放大模拟光场截面，图11(c)示出了不同照明模式下成像空间光强分布曲线的对比，其中NA＝0对应正入射照明，NA＝2.5对应SP波照明；
图12根据是本公开实施例的32nm线宽二维密集线条图形成像光刻结果，其中图12(a)示出了SP波照明二维超分辨成像光刻结构示意图，图12(b)示出了SP波照明方式下感光层区域成像模拟结果和白色虚线处的光强分布截面曲线，图12(c)示出了正入射照明下对照超分辨成像光刻结构示意图，图12(d)示出了对照结构感光层区域成像模拟结果和白色虚线处的光强分布截面曲线；
图13(a)是根据本公开实施例的超分辨成像结构，在不同的照明模式，相同的空气间隙(40nm)下，不同线宽线条图形的成像对比度模拟结果曲线，图13(b)是根据本公开实施例的32nm线宽密集图形在不同的照明模式，不同空气间隙下的成像对比度模拟结果曲线，其中SPI(Surface Plasmon Illumination)为NA＝2.5的SP波照明，NI(Normal Illumination)为NA＝0的正入射照明；
图14是根据本公开实施例的L型离散线条图形在离轴照明和引入沟槽结构后的光刻胶内成像光场模拟结果，其中图14(a)示出了感光层区域离轴照明和引入沟槽结构后成像光场分布，图14(b)示出了对照结构(正入射照明 和无沟槽结构)的成像光场分布，图14(c)为图14(a)和14(b)中白色虚线上的光强分布截面曲线对比图，14(d)为不同空气间隙下感光层区域成像宽度曲线。
具体实施方式
下文结合附图对本公开的实施例进行详细描述，本领域技术人员将会更加明了本公开的上述以及其他目的、优点和特征。在各个附图中，相同或相似的元件采用相同或相似的附图标记来表示，并省略重复的描述。为了清楚起见，附图中的各个部分没有按比例绘制。此外，在以下说明中，可以省略对公知结构和技术的描述，以避免不必要地混淆本公开的概念。
传统近场光学光刻、超透镜成像光刻无法实现间隙分离光刻的原因主要在于，在空气、液体等间隙空间，携带掩模亚波长图形信息的倏逝波离开超透镜表面后急剧衰减，高频信息强度的降低，从而导致成像分辨力和光刻对比度快速下降，无法实现有效的成像光刻。
根据本公开的实施例，可以根据超分辨成像光刻的图形线条宽度尺寸和图形结构，选择高NA离轴照明和/或表面等离子体波照明方式，调整掩模图形透射光场的空间频谱分布，将掩模图形的高频信息从高频倏逝波移动到低频倏逝波部分，从而降低超分辨成像过程中亚波长图形倏逝波信息的衰减幅度，实现长工作距间隙成像光刻。
以密集周期线条掩模图形为例，当掩模结构与光刻基片结构工作距离较大时，掩模结构图形透射光只有0级次到达光刻基片曝光，其它倏逝波级次严重衰减，成像光刻分辨力下降。采用表面等离子体(Surface Plasmon，SP)波照明，调节SP波照明场横向波矢使光栅掩模的透射光场发生空间频率移动，导致只有+1级(和/或-1级)和0级衍射光被耦合到成像空间相干叠加，由于减少了频谱空间零频波矢分量比重，从而可以提高成像对比度。此外，结合在感光层两侧引入辅助成像金属膜层结构，可以抑制成像空间区域中的纵向电偏振分量与横电偏振分量比值，从而减少成像光场纵向电场分量对成像质量的负面影响，实现进一步提高成像对比度。这两种机制可以有利地共同作用，实现掩模图形结构与光刻基片结构之间间隙的延伸，解决近场光学光刻技术中分辨力 下降和工作距短的问题，达到掩模图形层与光刻基片两者间隙分离的超分辨成像光刻效果，且获得高对比度成像光刻图形。另外，通过间隙分离超分辨成像光刻，可以有效提高光刻效率、减少掩模磨损和提高掩模寿命，便于实现高精度光学光刻对准、拼接。
如图1所示，根据本公开实施例的超分辨成像光刻设备可以包括照明系统101、掩模基底102、表面等离子体(SP)波照明光场激发结构103、掩模结构104、光刻基片结构105。掩模结构104下表面与光刻基片结构105上表面之间可以存在空气、真空或液体的隔离层，例如20nm到200nm之间。掩模结构104与光刻基片结构105之间的物理隔离，便于掩模图形保护。照明系统101、掩模结构104、光刻基片结构105各自的具体组成和结构、隔离层厚度等可以根据光刻图形线宽、维度、技术可实现的方便性等进行选择。
照明系统101可以包括光源、匀光模块和高数值孔径(例如，0＜NA＜1.8)照明光场整形光学结构。照明场数值孔径定义为照明场主光线与照明面法线的夹角正弦值与所在照明空间折射率的乘积。例如，为实现高NA的离轴照明光场，照明光场整形光学结构可以选择但不限于：固体或液体浸没式投影照明结构(如图2所示)，具有高折射率材料的固体棱镜照明结构(如图3所示)，或者分光光栅方式的照明结构(如图4所示)。
图2示出了根据本公开实施例的固体或液体浸没式投影照明结构的示意图。如图2所示，光源201发出的强度非均匀光场202可以通过匀光模块203成为强度均匀分布光束。可以采用光束整形元件204将正入射照明光场整形成远场二极、四极或环形照明方式。此时照明主光线角度假设为θ1＜θ，θ为期望的照明孔径角度。可以进一步采用缩放倍率为M倍的投影照明光学系统205(图2中205表示浸没式投影照明系统的简单示意结构)，光学系统205的像方可选择液体浸没或固体浸没方式，将照明主光线角度放大到M*sinθ1＝sinθ，并保持照明面积内光场强度均匀。
图3示出了根据本公开实施例的高折射率材料的固体棱镜照明结构。如图3所示，匀化后照明光束302、304可以分成两束或四束，分别从棱镜301、303两侧面或四侧面对称入射到棱镜中，从而在棱镜底面可以产生如公式(1)定义的入射角度的均匀照明场。对于沿二维正交方向排布的二维线条图形，棱镜 形式可以为四面锥形棱镜303。掩模图形线条方向与照明光方向基本上垂直。
棱镜301、303的材料选择可以根据照明光束的波长λ0来确定。例如，可以选择在照明光束波长下的高折射率透明玻璃材料，如照明光束的波长为365nm情况下，棱镜材料可以包括但不限于紫外透光的蓝宝石玻璃、融石英玻璃等材料。
图4示出了根据本公开实施例的分光光栅方式的照明结构的示意图。如图4所示，可以在掩模基底102上方加载一维或二维分光光栅402和滤波膜层结构403，以实现特定角度的高NA离轴照明光场。分光光栅402排布方向可以与掩模线条图形排布方向基本上一致。针对正入射均匀照明光场401，分光光栅402周期的选择可以使+1、-1级衍射满足公式(1)的要求，即
n×d_grating×sinθ＝λ0  (1)。
其中，d_grating为分光光栅402的周期，n为掩模基底材料的折射率，θ为基底材料内照明光场主光线(例如，+1、-1级衍射光线)与法线的夹角，λ0为光源真空波长。
为了滤除包括零级的其它级次干扰，分光光栅402后可以引入金属4031、介质4032多层膜组成的单个或多个F-P腔403，对+1、-1级衍射光而言满足共振条件高效透射，而对其它级次透射率近似为零。另外，为了消除分光光栅402的+1、-1级衍射光相干性带来的干涉噪声问题，掩模基底102厚度可以远大于光源干涉长度。
根据本公开的一个实施例，希望尽可能消除照明光场相干性，这是因为光场相干不仅带来相干噪声，影响均匀性，而且导致图形成像光场内部干涉带来不均匀性。一般而言，对于常用光刻光源，汞灯g线、i线、193nm波长ArF激光、157nm波长KrF激光光源而言，其光场部分相干性基本可以满足要求，但不排除设计特殊结构进一步降低光场部分相干性。另一方面，对于YAG三倍频激光器、气体激光器等长相干长度的激光光源而言，则希望在照明系统加入降低光场相干性的结构。本领域技术人员可以设想多种方式来降低光场相干性，具体方法这里不再赘述。
根据本公开的另一实施例，希望在基本上全部掩模图形照明区域范围内，实现相同照明方式的高均匀照明光强分布，例如光强起伏小于3％。本领域技 术人员可以设想多种均匀化照明方法，这里不再赘述。然而，对于一些掩模图形，例如微米量级图形、不同线宽纳米图形并存的情形，从技术可实现性出发，可以考虑在微米图形与不同线宽纳米图形区域选择不同照明方式的照明光场。本领域技术人员可以设想多种具体实现方法，这里不再赘述。
根据本公开的另一实施例，出于对一般掩模图形结构兼容性考虑，照明光场偏振可以选择为自然偏振方式。对于一些图形，如一维线条图形，可以在照明光路加入偏振器件，实现电场偏振方向与线条方向基本上垂直，也可以在一定程度上提高超分辨成像光场对比度，改善光刻效果。本领域技术人员可以设想具体实现方法，这里不再赘述。
另外，为提高照明功率，照明光场可以具有一定的发散角度范围，发散角可以在±10°范围内。
此外，光源波长可以选择与感光层材料匹配的波长，包括但不限于汞灯g线、i线、193nm波长ArF、157nm波长KrF光源等。
图5是根据本公开实施例的SP照明方式的超分辨成像光刻设备的部分示意图。
选择固体浸没照明结构(参见图2)或棱镜照明结构(参见图3)时，掩模基底501可以通过折射率匹配液或粘合胶固定至固体浸没投影照明系统205的底面(参见图2)或者棱镜301或303的底面(参见图3)。掩模基底501可以与棱镜301、303和固体浸没透镜205的材料折射率近似相同。
SP波照明光场激发结构103(参见图1)可以位于掩模基底501下方，掩模图形层503上方。该结构103从照明一例开始可以包括激发层结构5021、耦合层5022、由金属层5023、介质层5024交替多层膜层构成的杂波过滤层(为了描述方便，图5中仅画出了3对金属层5023和介质层5024)。
激发层结构5021可以是在掩模基底上制备的纳米结构层。该激发层结构可以接收远场照明光束513，高效激发特定传输波长的SP波。激发层5021中的纳米结构图形可以是一维或二维图形，例如特定周期的光栅结构。不同方向远场照明光激发相应方向表面传输的SP波。
耦合层5022辅助SP波高效耦合进入杂波过滤层。耦合层5022可以包括但不限于TiO2等高折射率介质膜层材料。杂波过滤层可以包括金属和介质交 替多层膜结构，每层厚度可以在纳米量级，包括但不限于金属Al和介质MgF2膜层交替堆叠的多层膜结构。杂波过滤层可以减少激发层结构5021激发SP过程产生其它级次的杂散光场干扰，在掩模图形层503上表面形成基本上均匀的SP波照明场。
如图5所示，掩模结构104从照明一例开始可以包括掩模图形层503、填充层504、成像膜层505、保护膜层506、间隙垫片膜层507。
掩模层503下方的填充层504可以包括介质材料，包括但不限于PMMA(polymethylmethacrylate)等。成像层505可以选择为金属膜层，其介电常数实部绝对值大小可以与填充层504介电常数实部相差不大。成像层505可以包括但不限于Ag、Au、Al等。例如，针对汞灯i线光源365nm中心波长，成像金属膜层可以包括Ag。对于193nm中心波长光刻光源，成像金属膜层可以包括Al。
保护层506可以防止掩模结构中成像层和图形层物理损伤和化学腐蚀。保护层厚度可以为5-10nm，材料可以包括但不限于SiO2、金刚石等致密膜层。
间隙垫片膜层507可以在间隙被动控制模式下，在曝光图形区域形成固定大小的间隙。
根据照明光场选择和成像光刻图形线宽，以及超分辨成像结构加工和光刻工艺的方便性，可以选择去除掩模图形层503上方的SP波照明光场激发结构502、掩模图形层503下方的填充层504、成像层505和保护层506之一、一些或全部，尽管这会导致一些成像光刻性能的降低。
如图5所示，光刻基片结构105从照明一例开始可以包括辅助成像膜层509、感光层510、反射层511，三者叠置在光刻基片512上。辅助成像膜层509、感光层510、反射层511三者构成SP共振腔体成像结构，反射层511可以用来调制感光层内部成像电场分量比重，提高成像光刻对比度。考虑到后续光刻工艺方便性，可以去除光刻胶上方的辅助成像膜层509，尽管这会导致一些成像光刻性能的降低。
感光层上方的辅助成像层509、下方的反射层511可以包括在光源波长范围内呈现负介电常数的金属材料，其介电常数实部大小可以与填充层504、感光层510的介电常数实部相差不大，包括但不限于Ag、Au、Al等。例如，针 对汞灯i线光源365nm中心波长，辅助成像膜层可以包括Ag。对于193nm中心波长光刻光源，辅助成像膜层可以包括Al。
照明场通过掩模图形层503，填充层504、成像层505和保护层506、真空、空气或液体隔离层508、辅助成像膜层509，将掩模结构中的图形成像在光刻基片结构中的感光层510空间。掩模图形层中纳米图形层503可以是一维或二维图形，纳米图形线条排布方向可以与激发层纳米图形线条排布方向或者离轴照明方向基本上一致。
可以根据超分辨成像光刻的图形线条宽度尺寸和图形结构，选择高NA离轴照明或者表面等离子体波照明方式。
考虑到集成电路图形以一维、二维方向的密集或者离散纳米线条图形为主，且密集的纳米线条图形是体现光刻分辨能力的主要难点，在此主要围绕纳米线条图形阐述如何根据光刻图形选择相应的照明方式。注意，选择标准并没有严格界限，可以根据技术实现可行性以及方便性加以变化。
根据一个实施例，对于线宽在1/6波长以上掩模图形，可以选择高数值孔径的一维、二维棱镜离轴照明、浸没式投影物镜照明或者光栅分光照明方式。
通过采用高数值孔径的离轴照明场可以有效提高1/6波长范围以上线宽在超分辨成像中的对比度，实现间隙分离超分辨成像光刻。这种高NA离轴照明场的主光线角度θ可以满足方程(2)
2×n×d×sin(θ)＝λ0  (2)
其中，d为掩模密集光刻线条图形的周期，θ为掩模基底材料内主光线与法线之间的夹角，λ0为光源真空波长，n为掩模基底材料折射率。其中n×sin(θ)为照明场数值孔径。在实际应用中，根据应用方便性需要，公式(2)无须严格满足，在例如+/-20％之内的误差都是允许的，虽然这会带来一定的成像光刻性能的下降。例如n×sin(θ)位于0.8λ0/(2d)～1.2λ0/(2d)区间范围。
假定曝光光源发出的光场已被进行了匀化处理。为实现公式(2)所要求的高NA照明，可以采用但不限于固体或液体浸没式投影照明结构(如图2所示)，或者具有高折射率的固体棱镜照明结构(如图3所示)，或者分光光栅方式的照明结构(如图4所示)。
以上根据超分辨光刻图形线宽选择照明结构方式的规则并不是一个严格 的标准。如果间隙较小，即便是1/6波长以下线宽图形也可以利用高NA离轴照明方式提高成像对比度和光刻质量。
根据另一实施例，对于线宽小于1/6波长的图形，可以在上述照明基础上，在掩模图形层上方引入SP波照明光场激发结构103。
采用SP波照明，可以等效为采用更高数值孔径的光场照明，调节SP波照明场横向波矢使掩模结构图形的衍射光发生空间频率移动，-1(或+1)级和0级衍射光可以被耦合到成像系统的传递频谱内发生干涉，从而提高对比度。SP波照明场通过照明掩模图形，携带图形光场信息，进一步通过填充层504、成像层505和保护层506、空气或液体隔离层508、辅助成像层509，将掩模结构中的图形成像在光刻基片结构中的感光层510区域。
SP波照明光场激发结构103、照明光、掩模图形可以满足以下方程(3)与(4)，
可以满足方程(3)与(4)：
2d(ds×n×sinθ+λ0)＝λ0ds  (3)
λsp(ds×n×sinθ+λ0)＝λ0ds  (4)
其中，d代表掩模密集线条图形的周期，ds代表激发层5021的光栅周期，中心波长为λ0、照明光场中心光线在掩模基底材料内的入射角度为θ，n为掩模基底材料折射率，λ0为远场照明光束的中心波长，λsp为激发的SP波波长。在实际应用中，根据应用方便性需要，公式(3)和(4)无须严格满足，在例如+/-20％之内的误差都是允许的，虽然这会带来一定的成像光刻性能的下降。
远场照明光束513的产生，可以利用但不限于上述高NA照明结构之一，如图2、图3和图4所示。
根据又一实施例，针对掩模图形层为非周期、离散形式的纳米图形，在上述方法基础上，可以进一步改进掩模图形结构，在具有较大间隙情形下，获得更好的成像光刻效果。
如图6所示，在掩模图形层金属膜601上，针对离散线条图案，可以在透明线条图案602边缘两侧对称加入1～2个沟槽结构603。在照明光场、沟槽和光刻基片上辅助成像膜层、感光层和反射层的共同作用下，掩模线条狭缝图形602透射光场中携带高频空间信息的倏逝波，散射并汇聚到感光层成像空 间，从而压缩图形发散，提高成像分辨力，如图6(b)所示。沟槽603的宽度可以为约1/3～1/7光源真空波长，深度可以约为1/5～1/7光源真空波长，沟槽中心距离掩模线条狭缝图形中心可以为约1/2～1/5光源真空波长。具体参数可以通过计算仿真进行优化，并综合考虑加工方便性。
如上所述，根据本公开的实施例，可以采用不同照明方式提高成像光刻性能，这与传统倾斜照明提高投影光刻物镜性能不同。根据本公开的实施例，可以针对超分辨成像光刻特点和光刻图形线宽指标，选择与之适应的高数值孔径照明方式，达到倏逝波、表面等离子体波范畴。在本公开的实施例中，照明产生方式与传统投影光刻物镜离轴照明不同，例如采用高折射率棱镜照明结构、SP激发和杂波滤波膜层结构等。
根据本公开的实施例，还提供了一种超分辨成像光刻设备。该设备可以包括照明光源、照明系统、成像光刻模块、成像间隙监测模块、工件台系统、对准光学系统、控制系统。
照明系统101可以包括实现照明二极、四极或环形光束整形的投影照明模块、棱镜照明模块、分光光栅照明模块等。
成像光刻模块可以包括上述掩模结构104、光刻基片结构105以及配套的装配控制机构等。
成像间隙监测模块可以实时监测掩模结构104下表面与光刻基片结构105上表面之间的间隙，包括但不限于采用FTP测试模块、白光干涉仪测试模块、电容位移传感器等。
对准光学系统可采用标记粗对准和莫尔条纹精密对准。
控制系统可以按被动控制和/或主动控制方式，控制掩模结构104、光刻基片结构105之间的间隙。
掩模基片为精密加工，具有高平整表面。为配合被动间隙控制，可以在掩模结构下表面引入间隙垫片间隔层，形成包含图形区的窗口结构，窗口高度为光刻间隙高度。工件台系统具有自适应调平结构，如柔性铰链等。
被动控制例如可以如下进行。如上所述，可以根据光刻图形线宽和类型，选择照明结构和参数。移动掩模结构104，实现具有间隙间隔层的掩模结构104下表面与光刻基片结构105接近。通过间隙检测模块，结合承片台调平机构， 将平均间隙控制在例如约1μm～10μm水平。通过对准光学系统，移动和转动承片台，实现对准。继续移动具有间隙间隔层的掩模结构104，实现间隙窗口结构膜层与光刻基片结构105上表面大面积、均匀接触。另外，也可以采用薄掩模基底或薄光刻基片，包括但不限于0.1mm～0.5mm厚度的融石英片等，采用增大掩模基片上方的气压，实现具有间隙间隔层的掩模结构104下表面与光刻基片结构105上表面大面积、均匀接触。在曝光过程中，虽然掩模基片与光刻基片部分物理接触，但由于窗口结构膜层的存在，掩模结构104始终与光刻基片结构105上表面保持固定的空气或液体间隙，从而避免了掩模图形损伤。
主动控制例如可以如下进行。精密控制掩模结构104下表面和光刻基片结构105上表面曝光图形区范围的平整度，处于10nm左右起伏范围。利用间隙检测模块，结合工件台系统的调平、位移机构，根据成像光刻设计需要，将曝光图形区域的间隙平均值控制在例如约20nm～200nm水平。
本公开的技术可以多种方式呈现，以下描述其中一些示例。
光源中心波长为汞灯i线365nm。在该实施例中，照明结构包括图3(a、b)中的蓝宝石屋脊棱镜(一维光刻图形)301或者四面锥蓝宝石棱镜(二维光刻图形)303。在该示例中，掩模基底光入射面与棱镜光出射面相邻紧密接触放置，例如通过折射率匹配液或粘合胶将掩模基底固定至棱镜的光出射面。
如图3(c)所示，采用蓝宝石掩模基底305、金属铬掩模图形层306、10nm厚度PMMA掩模图形填充层307、20nm厚度金属银成像膜层308、50nm金属铬-间隙垫片层310。汞灯i线光源，中心波长365nm，经过匀化后，分成两束光302或304，以对称方式从棱镜两侧面照明到掩模图形表面。照明主光线在棱镜中的照明角度为60°。棱镜折射率为1.8。对应照明数值孔径为1.5。
光刻基片结构105从上到下包括20nm厚度上层辅助成像银膜311、30nm厚度光刻胶感光层312、50nm厚度银膜反射层313、1mm厚度融石英基片314。
在曝光过程中，掩模结构下表面与光刻基片结构上表面紧密接触，由于间隙垫片层310的存在，形成了50nm厚度空气间隙，有效保护了掩模图形层结构。棱镜内的NA为1.5的离轴照明场通过掩模，将掩模纳米图形成像到融石英基底上的感光层中。通过曝光、去除光刻胶上面的辅助成像银膜，显影等步骤，实现纳米线条图案的成像光刻。
针对一维密集线条图形情形，线宽60nm，掩模深度50nm，周期120nm，占空比为1∶1，空气间隙厚度50nm。
利用数值仿真，对该实施例中成像光场结果进行了仿真。Cr、Ag、感光层的介电常数分别为-8.55+8.96i、-2.4012+0.2488i、2.59。其仿真成像结果如图7所示，给出了正入射照明(NA＝0，图7a)下以及该实施例(NA＝1.5，图7b)的成像模拟结果，图7c为两种照明方式下成像光场截线强度分布，其成像对比度分别为0.25和0.83。显然，根据本实施例，NA＝1.5情形下在感光层实现了很好的成像光刻质量。
图8给出了60nm线宽二维折线密集图形模拟结果。掩模图形层线宽60nm、相邻两线条间中心到中心的距离为120nm。空气间隙设置为50nm。此时，照明光束经过匀化后，分成四束光，分别从四面锥蓝宝石棱镜303四个侧面方向以棱镜材料内部60°入射角对称照明在掩模图形表面，方位角分别为0°、90°、180°与270°。
图8(a)是高数值孔径离轴(NA＝1.5)照明条件下光刻胶内成像光场模拟结果，图8(b)是对应图8(a)的像场截线光强分布，对比度为0.7。图8(c)是正入射(NA＝0)照明条件下光刻胶内成像光场模拟结果，图8(d)是对应图8(c)的像场截线光强分布，对比度为0.07。仿真结果表明，利用高数值孔径照明场，能很好地提高近场成像图形的对比度和光刻分辨力。
利用本公开的技术，开展了相关光刻实验。图9给出了间隙60nm情形下，NA＝0(图9(a))和NA＝1.5(图9(b))照明数值孔径下的60nm线宽密集线条图形光刻实验结果。相比而言，NA＝1.5照明数值孔径下的成像光刻结果无论对比度和成像质量都大幅提升。
如图5所示实施例中，利用SP波照明，线宽图形为32nm，周期为64nm的密集线条图形。所用汞灯i线光源波长365nm。
根据公式(3)和(4)，所需最佳SP照明光场等效数值孔径为2.8。为了兼容不同线宽图形和方便技术实施，本实施例设计了等效数值孔径为2.5的SP照明光场结构。基底501为融石英。如图5所示，两束彼此不相干的远场照明光场513的主光线入射角度为±28°(融石英基底材料中主光线与法线的夹角)，SP激发层5021光栅周期200nm，深度40nm，占空比为1∶1。针对一 维光刻掩模线条图形，5021激发光栅为一维结构，方向与光刻掩模线条方向基本上一致。光栅激发层5021可以接收远场照明光束513，以高效激发特定传输波长的SP波照明场。
SP激发层下面耦合层5022为75nm厚度TiO2膜层，5对15nm厚金属Al膜和15nm厚介质MgF2膜层材料的交替堆叠形成的多层膜结构作为SP杂波过滤层。对于SiO2、TiO2、MgF2、Al的介电常数分别为2.13、14.91+1.94i、1.932、-19.4238+3.6028i。
图10数值仿真表明，杂波过滤层MgF2/Al交替多层膜具有较好的滤波效果。图10中的灰色曲线展示了5对MgF2/Al交替的介质金属多层膜的OTF曲线(图中kx表示照明场横向波矢)，多层膜的光透射窗口空间波矢范围为1.5k0～3k0(k0表示真空波矢)。远场照明光照射SP激发层5021光栅上，产生了横向波矢为2.5k0的SP波照明场514。而照明场空间频谱的透过率如图10中的黑色柱状图分布，从图10中可以看到照明场的强度集中在空间频谱2.5k0上，其它频率的透过率被有效抑制。
掩模图形层504直接放置在照明场产生结构上(在该示例中，放置在SP激发结构502底部)。该SP波照明光场作用在掩模图形上，在空气间隙存在的情形下，可以大幅提高感光层内成像光场对比度。
线宽32nm，周期64nm，占空比为1∶1。这种掩模图形可以通过构图的金属材料如Cr来形成，Cr层厚度例如为40nm。为了技术实施方便，掩模图形下面设置为空气间隙。
感光层510为光刻胶，厚30nm。基底512可以包括例如1mm厚的石英。感光层510上方，面对照明场的一例，为辅助成像层为厚度15nm的Ag层。在该示例中，成像层509设置在掩模填充层上。在感光层510下方背对照明场的一例为70nm厚度金属银反射层511。三者叠层于石英基底512上。
利用数值仿真，对该实施例中的光刻胶内成像光场分布进行了仿真。Cr、Ag、感光层的介电常数分别为-8.57+8.66i、-2.4012+0.2488i、2.59。针对一维密集线条图形仿真成像结果如图11所示，其中图11(b)是图11(a)中白色虚线区域的放大。从图11(c)的成像空间光强分布对比结果可以看出，利用本实施例的结构，在感光层510内实现了很好的成像质量。
激发层5021结构依据掩模图形层503的具体图形而定。针对在掩模图形层503为二维图形的情况，激发层5021的图形亦可以为二维图形。具体仿真条件为：激发层图形为正方形孔阵光栅结构，孔边长为100nm，孔的中心间距200nm；图形层为二维折线，折线夹角90°，折线线宽32nm，周期64nm；入射光为中心波长365nm的四束非相干光照明，入射角28°，方位角分别为0°、90°、180°与270°。
利用数值仿真，对该实施例中的表面等离子波照明纳米成像设备及光刻结果进行了仿真。其仿真成像结果为图12所示，图12(a)是表面等离子波照明成像光刻结构示意图，图12(c)是正入射照明光刻示意图，图12(b)和12(d)分别表示这两种模式下的仿真结果图，图12(b)和12(d)中的插图是相应白色虚线上的强度分布。仿真结果表明，利用表面等离子波照明纳米成像光刻结构，能很好地提高超分辨成像光刻对比度和分辨力。
图13为该实施例中SP波光场横向波矢为2.5k0，40nm厚度空气间隙情形下不同线宽图形的SPI(Surface Plasmon Illumination)照明方式和NI(Normal Illumination)照明方式对比度曲线(图13(a))以及32nm线宽密集线条图形在不同空气间隙下的对比度曲线(图13(b))。从图13(a)可以看出，在固定表面等离子体波照明参数和40nm空气间隙的条件下，该结构针对32nm以上不同线宽密集线条图形均保持了高对比度成像。另外，从图13(b)可以看出，若感光层中像强度对比度大于0.4为判断标准，则空气间隙可以拓展到60nm。相比而言，采用正入射照明的成像光刻结构空气间隙只有10nm左右。
本公开提出了超分辨成像光学光刻方法，对于离散的纳米线条图形也是有效的。在此给出了60nm线宽孤立线条掩模图形的超分辨成像光刻实例。
在该实施例中，我们采取如同上一实施例的成像光刻结构和参数，如图6所示。如图6(a)所示，在60nm线宽铬掩模图形的线条缝隙602出射面两边，对称引入两组金属沟槽结构603。沟槽中心距离缝隙中心距离110nm，沟槽宽度55nm，沟槽深度45nm，掩模图形层601铬膜厚度90nm。如图6(b)所示，空气间隙604设置为100nm。由棱镜产生的NA＝1.5的倾斜照明场照射在掩模图形上方。光刻基片结构105配置为，20nm厚度金属银成像膜层605、30nm厚度光刻胶606和70nm金属银反射层607，以及0.3mm厚的硅片608。
图14给出了成像模拟结果。图14(a)为感光层区域离轴照明和引入沟槽结构后成像光场分布，图14(b)为对照结构(正入射照明和无沟槽结构)的成像光场分布，14(c)为沿图14(a)和14(b)中白色虚线的截面曲线，图14(d)为不同空气间隙下的光刻胶内线条图形宽度。可以看出图形线宽得到明显抑制，特别是针对空气间隙大于100nm的情形，成像线宽从300nm压缩到80nm左右。
根据本公开的实施例，光刻成像过程可以如下。可以针对光刻图形线宽选择照明方式。例如，对于1/6波长以上线宽图形，选择高NA离轴照明方法。对于1/6波长以下线宽图形，在中心波长为λ0、特定远场照明光束方向(入射光线中心方向与主光轴例如器件表面法线夹角为θ)的入射光场下，均匀照明掩模结构中的激发层，激发出特定传输波长的SP波。可以使用杂波过滤层使SP波透过强度增强。SP波照明场或者高NA离轴照明光场可以与掩模结构中的图形层进行耦合，传输掩模结构中的成像层。通过控制掩模结构与光刻基片结构之间的间隔层厚度，在光刻基片结构中辅助成像层的作用下，实现将携带图形层的成像光场穿透空气或液体间隔层，并耦合传递到光刻基片结构中的感光层内。通过曝光、去除辅助成像层及显影等光刻工艺，在感光层内实现超分辨成像光刻。
尽管上面对本公开说明性的具体实施方式进行了描述，以便于本技术领的技术人员理解本公开，但应该清楚，本公开不限于具体实施方式的范围，对本技术领域的普通技术人员来讲，在所附的权利要求限定和确定的本公开的精神和范围内，可以做出各种变化，这些变化在本公开的范围内。

Claims (22)

  1. 一种超分辨成像光刻设备，包括：
    照明光场产生装置，配置为产生通过掩模对掩模中包含的图形进行成像的照明光场，
    其中，照明光场包含高频空间频谱，使得透射通过掩模图形的光场空间频谱信息的高频倏逝波部分移动到低频倏逝波部分。
  2. 根据权利要求1所述的成像光刻设备，其中，照明光场产生装置被配置为按照表面等离子体(SP)波照明方式和/或高数值孔径(NA)照明方式，来形成照明光场。
  3. 根据权利要求2所述的成像光刻设备，其中，照明光场产生装置包括：
    光源，配置为发出照明光；
    匀光模块，配置为均匀化照明光；以及
    高NA照明光场整形光学结构，配置为将匀化后的照明光整形为包含高频空间频谱的照明光场。
  4. 根据权利要求2所述的成像光刻设备，其中，照明光场产生装置包括SP波照明光场激发结构，配置为接收特定方向对称入射的远场照明光束，产生特定传输波长的均匀SP波照明光场。
  5. 根据权利要求4所述的成像光刻设备，其中，SP波照明光场激发结构设置于掩模基底下，位于掩模图形层的光路上游，使得利用SP波照明光场照射掩模图形，通过掩模图形的透射光场携带图形信息，将掩模中的图形成像在光刻基片结构上。
  6. 根据权利要求4所述的成像光刻设备，其中，SP波照明光场激发结构包括激发层、耦合层以及由金属层、介质层交替设置的多层膜组成的杂波滤波膜层结构。
  7. 根据权利要求6所述的成像光刻设备，其中，激发层包括一维或二维的周期结构光栅图形，激发层的图形线条方向依据掩模图形线条方向设置。
  8. 根据权利要求4所述的成像光刻设备，其中，所述远场照明光束包括高NA照明光场。
  9. 根据权利要求6所述的成像光刻设备，其中，激发层满足方程(1)与(2)：
    2d×(ds×n×sinθ+λ0)＝λ0×ds  (1)
    λsp×(ds×n×sinθ+λ0)＝λ0×ds  (2)
    方程中d代表掩模密集线条图形的中心间距，ds代表激发层的光栅周期，远场照明光束中心光线在掩模基底材料内的入射角度为θ，n为掩模基底材料折射率，λ0为远场照明光束的中心波长，λsp为激发的SP波波长。
  10. 根据权利要求9所述的成像光刻设备，其中，激发层在约+/-20％误差的范围之内满足方程(1)和(2)。
  11. 根据权利要求3所述的成像光刻设备，其中，高NA照明光场整形光学结构包括分光光栅照明结构、固体或液体浸没式投影照明结构、或高折射率固体棱镜照明结构之一。
  12. 根据权利要求11所述的成像光刻设备，其中，分光光栅照明结构加载于掩模基底上，并包括一维或二维光栅和滤波膜层结构，其中，光栅线条排布方向与掩模线条排布方向实质上一致。
  13. 根据权利要求12所述的成像光刻设备，其中，滤波膜层包括单个或多个由金属、介质膜层组成的F-P腔结构，配置为滤除+1、-1级之外的衍射级次干扰。
  14. 根据权利要求3所述的成像光刻设备，其中，高NA照明光场主光线角度θ满足方程：
    n×2×d×sinθ＝λ0，  (3)
    其中，n为掩模基底材料折射率，θ为掩模基底材料内主光线与掩模基底法线的夹角，d代表掩模密集线条图形的中心间距，λ0为照明光的真空波长。
  15. 根据权利要求13所述的成像光刻设备，其中，在约+/-20％误差的范围之内满足方程(3)。
  16. 根据权利要求11所述的成像光刻设备，其中，高NA照明光场整形光学结构配置为将经匀化的照明光整形为二极、四极或环形照明光场，
    其中，固体或液体浸没式投影照明结构包括缩放倍率为M倍的液体浸没或固体浸没的投影照明光学系统，将该照明光场的NA增大到所需NA。
  17. 根据权利要求11所述的成像光刻设备，其中，高折射率固体棱镜照明结构包括屋脊棱镜或者四面锥形棱镜，其中，经均化的照明光从屋脊棱镜的两个相对侧面或者从四面锥形棱镜的四个侧面对称入射到棱镜中，且高NA照明光场从棱镜底面出射。
  18. 根据权利要求1所述的成像光刻设备，其中，掩模包括掩模图形层、介质填充层、成像膜层、保护膜层和间隙垫片膜层，
    成像膜层包括被配置为激发表面等离子体的金属膜层，其介电常数实部绝对值大小与填充层介电常数实部近似。
  19. 根据权利要求1所述的成像光刻设备，还包括：光刻基片结构，其包括叠置在光刻基片上的辅助成像膜层、感光层、反射层，
    辅助成像膜层、感光层、反射层构成SP共振腔体成像结构；以及
    辅助成像膜层、反射层包括在光源波长范围内呈现负介电常数的材料，其介电常数实部大小与感光层的介电常数实部近似相等。
  20. 根据权利要求19所述的成像光刻设备，其中，掩模与光刻基片结构之间隔开约20nm～200nm的间隙。
  21. 根据权利要求1所述的光刻设备，其中，掩模图形包括一维或二维的密集线条图形，还包括离散线条图形，
    其中所述离散线条图形配置为不透光膜层上的透光缝隙，且在透光缝隙周围设置结构，包括对称设置的1～2个沟槽结构，沟槽宽度为约1/5～1/10照明光波长，沟槽深度为约1/5～1/8照明光波长，沟槽中心距离缝隙中心距离约为1/3～1/5照明光波长。
  22. 一种超分辨成像光刻方法，包括：
    按照表面等离子体(SP)波照明方式和/或高数值孔径(NA)照明方式，形成包含高频空间频谱的照明光场；
    利用照明光场，照射掩模图形，得到透射通过掩模图形的光场，该透射光场空间频谱信息的高频倏逝波部分移动到低频倏逝波部分；以及
    透射光场经一定的间隙，投射到基片上，以将掩模图形成像在基片上。
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TWI789405B (zh) * 2018-07-12 2023-01-11 聯華電子股份有限公司 光罩

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3223063A1 (en) 2016-03-24 2017-09-27 Thomson Licensing Device for forming a field intensity pattern in the near zone, from incident electromagnetic waves
EP3312660A1 (en) 2016-10-21 2018-04-25 Thomson Licensing Device for forming at least one tilted focused beam in the near zone, from incident electromagnetic waves
EP3312646A1 (en) 2016-10-21 2018-04-25 Thomson Licensing Device and method for shielding at least one sub-wavelength-scale object from an incident electromagnetic wave
EP3312674A1 (en) 2016-10-21 2018-04-25 Thomson Licensing A photolithography device for generating pattern on a photoresist substrate
US10444161B2 (en) * 2017-04-05 2019-10-15 Kla-Tencor Corporation Systems and methods for metrology with layer-specific illumination spectra
EP3385219B1 (en) 2017-04-07 2021-07-14 InterDigital CE Patent Holdings Method for manufacturing a device for forming at least one focused beam in a near zone
CN109901362B (zh) * 2017-12-11 2022-04-19 中国科学院光电技术研究所 二次成像光学光刻方法和设备
CN109901363A (zh) * 2017-12-11 2019-06-18 中国科学院光电技术研究所 负折射成像光刻方法和设备
WO2019157438A1 (en) * 2018-02-09 2019-08-15 The Board Of Trustees Of The Leland Stanford Junior University Immersion lens array for the patterning of photoresist by maskless lithography

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050233262A1 (en) * 2004-04-16 2005-10-20 Riken Lithography mask and optical lithography method using surface plasmon
CN101441411A (zh) * 2008-12-25 2009-05-27 上海交通大学 表面等离子体共振曝光光刻方法
CN101825845A (zh) * 2009-12-25 2010-09-08 中国科学院光电技术研究所 一种用于高深宽比纳米图形加工的表面等离子体成像光刻方法
CN103454866A (zh) * 2013-09-24 2013-12-18 中国科学院光电技术研究所 基于表面等离子体波照明的光刻成像设备及光刻成像方法
CN103472689A (zh) * 2013-09-24 2013-12-25 中国科学院光电技术研究所 增强照明数值孔径超分辨光刻成像设备及光刻成像方法

Family Cites Families (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06250378A (ja) 1993-02-24 1994-09-09 Nikon Corp 露光方法及び該露光方法で使用されるフォトマスク
JPH08179493A (ja) 1994-12-22 1996-07-12 Hitachi Ltd 光露光または転写方法および装置またはそのためのマスク
JP3762091B2 (ja) 1998-02-10 2006-03-29 キヤノン株式会社 近接場光リソグラフィー方法
US7092069B2 (en) 2002-03-08 2006-08-15 Carl Zeiss Smt Ag Projection exposure method and projection exposure system
JP4018591B2 (ja) * 2003-05-12 2007-12-05 キヤノン株式会社 近接場光露光用フォトマスク、該フォトマスクを用いた近接場光強度分布の制御方法、パターン作製方法
CN100580557C (zh) 2003-05-29 2010-01-13 中国科学院光电技术研究所 一般波长或长波长光接触接近纳米光刻光学装置
CN1564084A (zh) 2004-04-16 2005-01-12 南昌航空工业学院 微光学器件数字分形掩模制作方法
JP4572406B2 (ja) 2004-04-16 2010-11-04 独立行政法人理化学研究所 リソグラフィーマスク
CZ299489B6 (cs) 2005-01-12 2008-08-13 Ústav fotoniky a elektroniky AV CR, v. v. i. Zpusob spektroskopie povrchových plazmonu pro senzory s povrchovými plazmony a senzorový element k provádení tohoto zpusobu
US20100003605A1 (en) 2008-07-07 2010-01-07 International Business Machines Corporation system and method for projection lithography with immersed image-aligned diffractive element
US20100033701A1 (en) * 2008-08-08 2010-02-11 Hyesog Lee Superlens and lithography systems and methods using same
JP5522944B2 (ja) 2009-01-09 2014-06-18 キヤノン株式会社 測定装置、測定方法及び露光装置
US20110188032A1 (en) * 2010-02-04 2011-08-04 Ravi Verma Far-field superlensing
CN103293863B (zh) 2012-02-24 2015-11-18 上海微电子装备有限公司 一种光刻照明系统
CN102866594B (zh) 2012-09-27 2014-09-10 中国科学院光电技术研究所 一种光栅辅助纳米成像的光刻方法
CN202948246U (zh) 2012-11-01 2013-05-22 中国科学技术大学 一种基于表面等离子体干涉的可重构亚波长光栅光刻机

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050233262A1 (en) * 2004-04-16 2005-10-20 Riken Lithography mask and optical lithography method using surface plasmon
CN101441411A (zh) * 2008-12-25 2009-05-27 上海交通大学 表面等离子体共振曝光光刻方法
CN101825845A (zh) * 2009-12-25 2010-09-08 中国科学院光电技术研究所 一种用于高深宽比纳米图形加工的表面等离子体成像光刻方法
CN103454866A (zh) * 2013-09-24 2013-12-18 中国科学院光电技术研究所 基于表面等离子体波照明的光刻成像设备及光刻成像方法
CN103472689A (zh) * 2013-09-24 2013-12-25 中国科学院光电技术研究所 增强照明数值孔径超分辨光刻成像设备及光刻成像方法

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
FANG N; LEE H; SUN C; ZHANG X: "Sub-diffraction-limited optical imaging with a silver superlens", SCIENCE, vol. 308, 2005, pages 534 - 537, XP001229203, DOI: doi:10.1126/science.1108759
PENDRY JB: "Negative Refraction Makes a Perfect Lens", PHYS.REV.LETT., vol. 85, 2000, pages 3966 - 3969, XP001001470, DOI: doi:10.1103/PhysRevLett.85.3966
WANG, PEI ET AL.: "Nano-photolithography using super-resolution near-field structure", CHINESE JOURNAL OF QUANTUM ELECTRONICS, vol. 22, no. 6, 31 December 2012 (2012-12-31), pages 840 - 843, XP008183132 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TWI789405B (zh) * 2018-07-12 2023-01-11 聯華電子股份有限公司 光罩

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