WO2022116959A1 - 一种步进式光刻机、其工作方法及图形对准装置 - Google Patents

一种步进式光刻机、其工作方法及图形对准装置 Download PDF

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WO2022116959A1
WO2022116959A1 PCT/CN2021/134287 CN2021134287W WO2022116959A1 WO 2022116959 A1 WO2022116959 A1 WO 2022116959A1 CN 2021134287 W CN2021134287 W CN 2021134287W WO 2022116959 A1 WO2022116959 A1 WO 2022116959A1
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wafer
area
exposure
dimensional
mark
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PCT/CN2021/134287
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English (en)
French (fr)
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周向前
尹志尧
朗格诺
杜川
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百及纳米科技(上海)有限公司
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Priority to KR1020237022660A priority Critical patent/KR20230136116A/ko
Priority to JP2023534009A priority patent/JP2023552403A/ja
Priority to EP21899990.2A priority patent/EP4258057A1/en
Priority to US18/255,784 priority patent/US20240103373A1/en
Publication of WO2022116959A1 publication Critical patent/WO2022116959A1/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
    • G03F7/20—Exposure; Apparatus therefor
    • G03F7/2002—Exposure; Apparatus therefor with visible light or UV light, through an original having an opaque pattern on a transparent support, e.g. film printing, projection printing; by reflection of visible or UV light from an original such as a printed image
    • G03F7/2004—Exposure; Apparatus therefor with visible light or UV light, through an original having an opaque pattern on a transparent support, e.g. film printing, projection printing; by reflection of visible or UV light from an original such as a printed image characterised by the use of a particular light source, e.g. fluorescent lamps or deep UV light
    • 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
    • G03F9/00—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically
    • G03F9/70—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically for microlithography
    • G03F9/7049—Technique, e.g. interferometric
    • G03F9/7053—Non-optical, e.g. mechanical, capacitive, using an electron beam, acoustic or thermal waves
    • G03F9/7061—Scanning probe microscopy, e.g. AFM, scanning tunneling microscopy
    • 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
    • G03F9/00—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically
    • G03F9/70—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically for microlithography
    • G03F9/7073—Alignment marks and their environment
    • G03F9/7076—Mark details, e.g. phase grating mark, temporary mark
    • 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
    • G03F7/70483—Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring
    • G03F7/70491—Information management, e.g. software; Active and passive control, e.g. details of controlling exposure processes or exposure tool monitoring processes
    • G03F7/70541—Tagging, i.e. hardware or software tagging of features or components, e.g. using tagging scripts or tagging identifier codes for identification of chips, shots or wafers
    • 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
    • G03F9/00—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically
    • G03F9/70—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically for microlithography
    • G03F9/7003—Alignment type or strategy, e.g. leveling, global alignment
    • G03F9/7019—Calibration
    • 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
    • G03F9/00—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically
    • G03F9/70—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically for microlithography
    • G03F9/7073—Alignment marks and their environment
    • G03F9/7084—Position of mark on substrate, i.e. position in (x, y, z) of mark, e.g. buried or resist covered mark, mark on rearside, at the substrate edge, in the circuit area, latent image mark, marks in plural levels
    • 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
    • G03F9/00—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically
    • G03F9/70—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically for microlithography
    • G03F9/7096—Arrangement, mounting, housing, environment, cleaning or maintenance of apparatus

Definitions

  • the present invention relates to the technical field of photolithography, in particular to the technical field of overlay alignment and positioning of photolithography patterns.
  • microelectronics and optoelectronics have led to the rapid development of integrated circuit chips and integrated optical chips. These industries have become the foundation of modern computers, display screens and even the core devices and chips of the entire information industry. At present, the technology node of the modern chip industry has reached 5 nanometers or even smaller.
  • Lithography technology includes ordinary optical lithography technology, deep ultraviolet/extreme ultraviolet lithography technology, electron beam lithography technology, ion beam lithography technology, etc. With the help of these key lithography techniques, fine lithography patterns and even all-encompassing micro-nano device structures, such as integrated circuit chips and optoelectronic integrated chips, can be produced.
  • the alignment accuracy that is, the overlay accuracy, cannot be at least several times smaller than the minimum size of the circuit pattern on the wafer area. That size is currently around 5-10 nanometers.
  • the multi-beam electron beam lithography machine used to make the mask such as the MBMW-101 series of the Austrian high-tech company IMS, can be used for the production of the 5-nanometer node mask, and its overlay alignment accuracy is below 5 nanometers.
  • the lithography machine series TWINSCAN3400B and 4300C of the Netherlands EUV optical lithography machine ASML are used for the 5nm technology node, and their overlay accuracy is 2.5nm and 1.5nm respectively.
  • the size of the chip structure will enter the order of 3 nanometers.
  • the alignment and positioning accuracy of the lithography machine facing the exposure of the wafer area must be required to be 1 nanometer or less.
  • the overlay accuracy of the wafer area there is currently no relevant positioning technology, so new technologies must be invented.
  • the difficulty in realizing the extremely high positioning accuracy of the wafer table is also a feature of the photolithography process, and it is also a huge disadvantage, that is, the wafer is coated with a photosensitive layer on the wafer before exposure.
  • the photolithography pattern will be transferred to the photosensitive layer by exposure, and then the photolithography pattern on the photosensitive layer will be transferred to the wafer by the etching process.
  • the photosensitive layer on the wafer is used as the upper surface of the covering wafer. This upper surface is "phobic" so that the electron beam or photon beam cannot be irradiated (that is, exposure) for surface observation before exposure.
  • the pattern of the wafer under the photosensitive layer cannot be obtained through the photosensitive layer.
  • the pattern to be exposed cannot be aligned with the pattern of the wafer area under the photosensitive layer, that is, the lithography machine can only be "blind operation”, move the wafer table and then expose the beam "blind operation". As a result, the positioning of the wafer exposure is inaccurate and the overlay error is large.
  • the present invention provides a lithography pattern alignment device, the device is located in a lithography machine body, including:
  • a wafer table is used to carry the wafer to be processed, the wafer includes a number of wafer areas and an off-site area around the wafer area, the surface of the wafer is provided with a photosensitive layer, and the photosensitive layer is provided with a three-dimensional mark, so the three-dimensional mark has an area that is not at the same level as the upper surface of the photosensitive layer;
  • a nano-needle-tip sensing device comprising a needle-tip sensing head, the needle-tip sensing head is located above the photosensitive layer, and is used to move and scan in the scanning area and determine the coordinates of the three-dimensional mark in the scanning area;
  • An exposure beam generating device is used to provide an exposure beam required for exposing the wafer area, and form a projection exposure area on the photosensitive layer;
  • a displacement driving device for adjusting the relative position of the exposure beam generating device and the wafer table according to the three-dimensional mark coordinates measured by the needle tip sensor head, so that the projection exposure area is aligned with the wafer area to be exposed .
  • the device further includes a computer control system
  • the computer control system is configured to receive the three-dimensional marker coordinates measured by the nano-tip sensing device and compare them with the reference coordinates of the three-dimensional marker to obtain the difference between the two coordinates. value
  • the computer control system is used to transmit the difference value to the displacement driving device, and control the exposure beam generating device and/or the wafer stage to move relative to each other to compensate for the difference value.
  • the reference coordinates are preset position coordinates of the three-dimensional mark.
  • the wafer area to be exposed is aligned with the projection exposure area, and the reference coordinates are stored in advance. in the computer control system.
  • the reference coordinates are the coordinates measured by the nano-tip sensing device on the three-dimensional mark before exposing the wafer area and the theoretical crystal in order to achieve the alignment of the next wafer area to be exposed and the projection exposure area.
  • the distances to be moved by the circle are combined with the corresponding coordinates in the scanning area, and theoretically, the distances to be moved by the wafer in the lateral and longitudinal directions are pre-stored in the computer control system.
  • the three-dimensional mark on the photosensitive layer includes a bottom alignment mark disposed under the photosensitive layer, a three-dimensional mark correspondingly formed on the photosensitive layer and/or a radiation-induced photosensitivity formed by an exposure beam after exposing the surface of the photosensitive layer.
  • the three-dimensional mark corresponding to the bottom alignment mark formed on the photosensitive layer is located in the wafer area or in the off-field area between adjacent wafer areas.
  • the bottom layer alignment marks include marks fabricated on the surface of the wafer substrate before the first exposure of the wafer and/or marks disposed under the photosensitive layer in a subsequent exposure process.
  • the height of the three-dimensional mark is greater than the surface roughness of the photosensitive layer.
  • the coordinates of the three-dimensional mark include lateral position coordinates, longitudinal position coordinates and circumferential position coordinates of the wafer.
  • the circumferential position coordinates of the three-dimensional mark refer to the coordinates of the three-dimensional mark in the circumferential direction, that is, the angular coordinates of the graphics of the three-dimensional mark in the circumferential direction.
  • two or more three-dimensional marks are provided on the photosensitive layer.
  • the three-dimensional mark has a certain graphic feature, and the graphic feature includes at least one point-like feature, and the point-like feature and the upper surface of the photosensitive layer are located in different horizontal planes.
  • the graphic feature further includes a ridgeline feature connected to the point-shaped feature, and the ridgeline feature and the upper surface of the photosensitive layer are not completely located in the same plane.
  • the three-dimensional mark is a three-dimensional structure protruding or recessed on the upper surface of the photosensitive layer.
  • the three-dimensional structure is at least one of a conical structure, a polygonal prismatic structure, and a pyramidal structure.
  • each wafer area corresponds to at least one three-dimensional mark
  • the three-dimensional mark is located in the wafer area or an off-field area around the wafer area
  • the reference coordinates of the three-dimensional mark are pre-stored in the computer control system.
  • part of the wafer area is not provided with a corresponding three-dimensional mark, and the wafer area is aligned with the projection exposure area according to the three-dimensional pattern three-dimensional mark in the previously exposed wafer area measured by the needle tip sensor head.
  • the wafer area where the corresponding three-dimensional mark is not provided is spaced from the wafer area where the corresponding three-dimensional mark is provided.
  • a positioning mark generating device is provided on the exposure beam generating device, and the positioning mark generating device forms a three-dimensional positioning mark on the periphery of the wafer area when the wafer area is exposed, and the needle tip sensor head treats the stereo positioning mark according to the three-dimensional positioning mark.
  • the position of the exposed wafer area is calibrated.
  • the height of the three-dimensional mark is less than or equal to 50 microns.
  • the needle tip sensing head is one of an active atomic force needle tip sensing head, a laser reflection atomic force needle tip sensing head, a tunnel electron probe sensing head, or a nanoscale surface work function measurement sensing head or various combinations.
  • the needle tip sensing head measures the wafer surface structure in an atmosphere or a vacuum environment, or the needle tip sensing head is immersed in a liquid to measure the wafer surface structure in a liquid immersion environment.
  • the three-dimensional mark is a three-dimensional mark in a liquid immersion environment, or a three-dimensional mark corresponding to a wafer area and an adjacent wafer area in a liquid immersion environment outside the exposure beam.
  • the surface structure data of the three-dimensional mark measured by the needle-tip sensing head is a mathematical convolution of the three-dimensional mark surface structure and the needle-tip structure of the needle-tip sensing head, and the needle-tip sensing head is in the three-dimensional mark.
  • the measurement and calibration of the tip structure is performed before marking the measurement.
  • the nano-tip sensing device further includes a micro-cantilever, one end of the micro-cantilever is fixed, and one end is provided with the needle-tip sensing head.
  • the nano-tip sensing device includes one or more needle-tip sensing heads, and the needle-tip sensing heads are fixed on one side or both sides of the exposure beam generating device through the microcantilever.
  • the exposure beam generating device includes a projection objective lens group disposed above the wafer, and the one or more needle tip sensing heads are fixed on one or both sides of the projection objective lens group through a micro-cantilever. .
  • the wafer table includes a moving part and a fixed part, and the tip sensing head is connected to the fixed part through the micro-cantilever.
  • the nano-tip sensing device includes two or more needle-tip sensing heads, wherein one or more of the needle-tip sensing heads are fixed on the fixed part of the wafer table, and one Or more than one of the tip sensor heads are fixed to the side of the exposure beam generating device.
  • the nano-tip sensing device includes two or more needle-tip sensing heads, and a plurality of the needle-tip sensing heads are fixed on one side or both sides of the exposure beam generating device through a connector, The relative distance between several of the needle tip sensing heads is fixed.
  • the nano-tip sensing device includes three or more needle-tip sensing heads, and the needle-tip sensing heads are fixed on the fixed part of the wafer table through connectors and/or fixed by connectors.
  • the needle tip sensing heads are located on different straight lines to determine whether the wafer is perpendicular to the exposure beam.
  • each of the needle tip sensor heads tests the distance from the surface of the wafer or the surface of the photosensitive layer corresponding to its position to the exposure beam generating device, and judges whether the wafer is perpendicular to the exposure beam according to whether the measured distances are the same or not, and
  • the wafer table is driven by a computer control system to adjust so that the wafer is perpendicular to the exposure beam.
  • the nano-tip sensing device includes a plurality of needle-tip sensing heads fixed by connectors, and the multiple needle-tip sensing heads are arranged in a row laterally according to the distribution of the wafer area to form a horizontal needle-tip transmission. Sensing head array.
  • one end of the horizontal needle tip sensing head array is provided with at least one needle tip sensing head distributed longitudinally to form an L-shaped needle tip sensing head array.
  • two ends of the horizontal needle tip sensing head array are respectively provided with vertically distributed needle tip sensing heads to form a U-shaped needle tip sensing head array.
  • the distance between the two adjacent needle tip sensing heads is greater than or equal to the lateral width of one wafer area.
  • the displacement driving device includes a wafer area switching driving device and a nano-displacement driving device.
  • the wafer area switching drive device is connected to the moving part of the wafer table, and is used to drive the wafer areas to be exposed to be exposed under the projection exposure area in sequence.
  • the moving part of the wafer stage further includes a precision moving device, and the nano-displacement driving device is the precise moving device.
  • the nano-displacement driving device is connected to the exposure beam generating device and/or the precise moving device of the wafer stage, and is used to control the exposure beam generating device and/or the wafer stage Move laterally and/or longitudinally and/or circumferentially.
  • the working principle of the nano-displacement driving device for driving the exposure beam generating device and/or the precise moving device to move is at least one of a piezoelectric principle, a voice coil driving principle or an electromagnetic driving principle.
  • the exposure beam emitted by the exposure beam generating device is at least one of a light beam, an electron beam, an ion beam or an atomic beam.
  • the exposure beam generating device is a beam generating device
  • the beam generating device includes a light source, a shutter, a beam deflector/reflector, a mask and a projection objective lens group, and the nano-displacement driving device is connected to the beam.
  • a deflecting plate/reflector, the mask plate is connected to at least one of the projection objective lens groups, so as to adjust the position of the projection exposure area of the light beam generating device.
  • the at least one needle tip sensing head is fixed on at least one side of the projection objective lens group.
  • the beam is a parallel beam or a Gaussian beam.
  • the beam shaping and focusing system may be composed of an optical lens, or may be composed of an optical mirror.
  • the wafers include complete wafers, partial wafers, or non-wafer substances that require lithography exposure processing.
  • the present invention also discloses a step-by-step lithography machine for repeating exposure to multiple wafer regions in the wafer, and the lithography machine is provided with the above-mentioned lithography pattern alignment device.
  • the present invention also discloses a working method of a stepper lithography machine, the method comprising:
  • At least one bottom layer alignment mark is arranged on the wafer, and a photosensitive layer is coated on the wafer to be processed, and the bottom layer alignment mark forms a three-dimensional mark correspondingly on the photosensitive layer;
  • the wafer provided with the three-dimensional mark in the preparation step is placed in the lithography machine described above, and a projection objective lens group is arranged near the wafer in the lithography machine, and the projection objective lens group is placed on the wafer.
  • a projection exposure area is corresponding to the upper part, and the wafer table is driven to place the first wafer area to be exposed under the projection objective lens group;
  • the photosensitive layer is scanned by the needle tip sensing head in a certain scanning area to obtain The position coordinates of the first three-dimensional mark, compare the position coordinates of the first three-dimensional mark with the reference coordinates of the first three-dimensional mark, and obtain the difference between the two position coordinates;
  • the displacement driving device is based on the difference between the two position coordinates. adjusting the relative positions of the exposure beam generator and the wafer stage so that the projection exposure area is aligned with the first wafer area;
  • the light beam generating device emits an exposure beam to the first wafer area of the wafer to realize the exposure of the first wafer area.
  • the second wafer area is placed under the projection objective lens group, and the needle tip sensor head scans the moved position coordinates of the first three-dimensional mark and compares it with the first three-dimensional mark.
  • the reference coordinates after the movement of the first three-dimensional mark are compared to obtain the deviation of the two position coordinates, and the displacement driving device adjusts the relative position of the exposure beam generating device and the wafer stage according to the difference of the position coordinates. , so that the projection exposure area is aligned with the second wafer area, and the exposure of the second wafer area is realized.
  • the reference coordinates after the movement of the first three-dimensional mark are the position coordinates of the first three-dimensional mark when the first wafer area is exposed and are aligned with the projection exposure area for realizing the next wafer area to be exposed, and the wafer
  • the distances to be moved in the horizontal and vertical directions are combined in the corresponding coordinates in the scanning area.
  • At least one needle tip sensing head is respectively provided on both sides of the projection objective lens group, or a needle tip sensing head is set on one side of the projection objective lens group, and the scanning width of the needle tip sensing head is greater than one standby. The width of the exposed wafer area.
  • the second wafer area is placed under the projection objective lens group, and the needle tip sensor head scans the position coordinates of the second three-dimensional mark and associates it with the second three-dimensional mark.
  • the deviation of the two position coordinates is obtained by comparing the reference coordinates of Align with the second wafer area, and realize the exposure of the second wafer area, and the reference coordinates of the second three-dimensional mark are pre-stored in the computer control system.
  • the first three-dimensional mark is disposed close to the first wafer area, and/or the second three-dimensional mark is disposed close to the second wafer area.
  • the second wafer area is placed under the projection objective lens group, and the needle tip sensor head scans the first wafer area for exposure formed on the photosensitive layer.
  • the graphics and coordinates of the three-dimensional pattern are compared with the preset graphics and coordinates of the three-dimensional pattern to obtain the difference between the positions of the two three-dimensional patterns, and the displacement driving device adjusts the exposure beam generating device and the position coordinates according to the difference.
  • the relative position of the wafer table is such that the projection exposure area is aligned with the second wafer area, and the exposure of the second wafer area is achieved.
  • the nano-needle tip sensing device is fixed on one side or both sides of the projection objective lens group, and is relatively fixed in position with the projection objective lens group.
  • the lithography technology that the lithography pattern alignment device of the present invention can target is deep ultraviolet and extreme ultraviolet lithography machines, for example, ultraviolet stepper type repeated exposure lithography machines (Stepper). It is characterized in that the light beam forms an exposure pattern through a mask and irradiates the wafer coated with a photosensitive layer. Each time a wafer area is aligned and exposed, another wafer area is aligned and exposed by the movement of the wafer table, and finally all the wafer areas on the wafer are exposed.
  • the present invention can also be applied to an electron beam/photon beam direct writing lithography machine.
  • three-dimensional marks are set on the surface of the wafer, and the coordinate relationship between these three-dimensional marks and each wafer area can be fixed by one measurement of the wafer, so that the accurate coordinates of the wafer area can be located by measuring these three-dimensional marks in the future. Location. If the wafer is not deformed due to thermal expansion and contraction during a relatively long period of time through precise temperature control, the positioning between these coordinates can easily be accurate to the single nanometer level.
  • the first measurement of these three-dimensional marks and the position of the wafer area is to determine the relative deviation of the wafer relative to the wafer table, especially whether the wafer needs to be rotated when the wafer table moves to adjust the movement of the wafer table.
  • the parallelism of the die area array on the wafer is to determine the relative deviation of the wafer relative to the wafer table, especially whether the wafer needs to be rotated when the wafer table moves to adjust the movement of the wafer table.
  • photon beam lithography machines deep ultraviolet lithography machines and extreme ultraviolet lithography machines
  • the measurement reaches nanometer-level resolution, so the photon beam cannot participate in the alignment and positioning of single nanometer and below dimensional accuracy.
  • the positioning accuracy of the photon beam lithography machine can be at the nanometer and sub-nanometer level.
  • Three-dimensional marks are set between wafer areas or within wafer areas, which is the type for step-and-repeat lithography machines. If the 3D mark placed inside the wafer area can be as small as a few nanometers to several hundreds of nanometers, it will be very practical because it occupies a small area, and even if the 3D mark is made in the wafer area, it will not affect the wafer. Regional yield issues.
  • the present invention adopts the measurement technology capable of sensing the three-dimensional nanoscale structure, for example, the sub-nanometer three-dimensional topography measurement technology (sub-nanoscale atomic force three-dimensional topography measurement technology) is realized by using the needle tip sensing head sensing technology, then the nanoscale three-dimensional topography Markers can be measured by tip sensing technology to play the role of nanoscale coordinates.
  • the three-dimensional marks on the photosensitive layer and the wafer surface can be used as alignment marks. For example, by measuring the peak position or recess position of the three-dimensional mark, an accurate alignment coordinate can be determined.
  • the concave-convex structure on the wafer surface generally causes the surface of the photosensitive layer covering it to follow to form a concave-convex structure, that is, the positioning can penetrate vertically, so that the surface covering the photosensitive layer can be measured due to its concave-convex structure and position.
  • the sensing technology of the needle tip sensor head adopted in the present invention can make the optical measurement reach the sub-nanometer level measurement.
  • the present invention can also perform the positioning of the exposure of the wafer area according to the characteristics of the modification of the photosensitive layer induced by irradiation.
  • ) means that the chemical and/or physical properties of the photosensitive layer are changed at the location exposed by photon beam or electron beam or other particle beam irradiation.
  • the chemical changes include photon beam/electron beam-induced chemical reaction on the surface of the photosensitive layer, which causes the irradiated part of the photosensitive layer to change from an insoluble state to dissolve during development (positive glue), or the dissolved state reacts to insoluble (negative glue) through exposure. ).
  • Photon beam/electron beam exposure can also cause physical changes in the photosensitive layer, including small geometrical changes on the surface of the photosensitive layer, such as swelling or shrinking at sub-nanometer or nanoscale to form concave-convex structures.
  • the photon beam/electron beam exposure transfers the exposure pattern information to the photosensitive layer, the concave-convex structure change on the photosensitive layer is also produced. This deformation can be sensed at the sub-nanometer scale by probe tip sensing head (highly sensitive sensing head).
  • FIG. 1 shows a schematic diagram of an alignment device for a lithography pattern according to the present invention.
  • FIG. 2 shows a schematic structural diagram of a lithography machine according to a specific embodiment.
  • FIG. 3 shows a schematic diagram of the position of the three-dimensional mark on the wafer.
  • FIG. 4A is a schematic diagram of a protruding three-dimensional mark on the surface
  • FIG. 4B is a schematic diagram of a concave three-dimensional mark on the surface
  • FIG. 4C is a schematic diagram of a surface concave-convex three-dimensional mark
  • FIG. 4D is a three-dimensional structure schematic diagram of a three-dimensional mark.
  • FIG. 5A is a schematic diagram of the structure of the radiation-induced expansion of the photosensitive layer
  • FIG. 5B is a schematic diagram of the structure of the radiation-induced contraction of the photosensitive layer.
  • FIG. 6 shows a schematic structural diagram of a lithography machine according to another embodiment of the present invention.
  • FIG. 7 shows a schematic structural diagram of a lithography machine according to another embodiment of the present invention.
  • FIG. 8 is a schematic diagram illustrating the corresponding relationship between a plurality of tip sensing heads and wafer areas according to an embodiment of the present invention.
  • FIG. 9 is a schematic diagram showing the correspondence between the tip sensing head and the wafer area according to another embodiment of the present invention.
  • FIG. 10 is a schematic diagram showing the correspondence between the tip sensing head and the wafer area according to another embodiment of the present invention.
  • the alignment of the lithography machine mainly realizes the alignment of the wafer area on the wafer with the beam projection exposure area through the precise positioning of the wafer table.
  • This alignment introduces positioning errors caused by wafer table movement.
  • the alignment error caused by the beam offset cannot be corrected in time.
  • the entire positioning process belongs to an open-loop control state in which there is no coordinate measurement before positioning and no coordinate measurement after positioning. There is no real-time measurement of alignment error and feedback information using alignment error. This error is generally several nanometers or even dozens of nanometers.
  • the precision of the laser wafer stage can be obtained by processing the high power of the light wavelength of the laser interference to the precision of several nanometers.
  • the driving device of the wafer table can be a piezoelectric driving mode or even a voice coil driving mode. Its mobile positioning accuracy can reach sub-nanometer or even picometer level.
  • the problem is that the position measured by laser interferometry is the distance of the optical path, not necessarily the distance that the actual wafer stage needs to move. As long as there is a slight temperature change around the wafer table or the beam, changes in air concentration and air pressure will cause inconsistencies between the optical path difference and the actual distance, so that the distance measured by the laser is not the actual distance that the wafer table needs to move. .
  • some deep ultraviolet and extreme ultraviolet optical lithography machines have a laser interference positioning mechanism between the wafer and the exposure beam, that is, the part of the lithography machine that forms one side of the wafer is connected to the exposure beam, and this side passes through The laser interference forms mutual positioning.
  • This is a closed loop control system.
  • a grating structure is arranged in the middle of the wafer area. The laser is emitted from the part of the lithography machine connected to the exposure beam to the grating structure in the middle of the wafer area, and then returns to the part of the lithography machine connected to the exposure beam to interfere with the emitted laser, or to form a double with the grating on one side of the exposure beam.
  • grating interference is arranged in the middle of the wafer area. The laser is emitted from the part of the lithography machine connected to the exposure beam to the grating structure in the middle of the wafer area, and then returns to the part of the lithography machine connected to the exposure beam to interfere with the emitted laser
  • the movement of the interference fringes corresponds to the relative movement between the wafer area and the exposure beam.
  • the positioning accuracy achieved in this way is feasible on the order of 20 nanometers or even several nanometers. But once it enters one nanometer or even sub-nanometer positioning, the drift and jitter of its interference fringes will greatly affect the determination of the actual positioning.
  • the present invention discloses a technical solution that can accurately position the wafer and realize the alignment of the wafer area to be exposed and the projection exposure area according to the positioning result.
  • the technical solution can find the positioning error in the wafer area, and then solve and eliminate the positioning error problem, so as to achieve sub-nanometer alignment and overlay.
  • Embodiments of the present invention provide an apparatus and method for sub-nanometer overlay alignment of an optical lithography machine, and an application scenario on a lithography machine system.
  • the wafer worktable is used as a rough positioning for the overetching alignment of the wafer area on the wafer of the lithography machine and the projection exposure area.
  • the detailed overlay alignment and positioning is performed after the positioning error is measured and the error compensation is implemented.
  • this subtle error compensation can be realized by a sub-nanometer displacement driving device.
  • the present invention solves the sub-nanometer displacement of the driving object and the alignment method so that the chip area on the wafer and the projection exposure area can reach the sub-nanometer level. Huge improvement in level overlay alignment accuracy.
  • the wafer includes a number of wafer areas 120 and an off-field area 122 around the wafer area, at least one bottom alignment mark is provided on the wafer, a photosensitive layer 130 is provided on the wafer surface, and the bottom alignment mark is on the photosensitive layer Corresponding three-dimensional marks are formed, the three-dimensional marks having regions that are not at the same level as the upper surface of the photosensitive layer.
  • the three-dimensional mark of the present invention includes the three-dimensional mark formed on the photosensitive layer by the bottom alignment mark pre-arranged on the wafer, and also includes the three-dimensional pattern three-dimensional mark formed on the photosensitive layer according to the characteristics of the modification of the photosensitive layer induced by irradiation. .
  • FIG. 1 shows a schematic diagram of a lithography pattern alignment device of the present invention.
  • the alignment device is located in a lithography machine body, and the lithography machine body includes: a wafer table 100 for carrying a waiting
  • the wafer 110 is processed, and the lithography machine involved in the present invention is a step-by-step lithography machine, and the purpose of sequentially exposing different wafer areas of the wafer is realized by moving the wafer stage step by step.
  • a nano-tip sensing device 90 is arranged above the wafer worktable.
  • the nano-tip sensing device includes at least one needle-tip sensing head 91.
  • the needle-tip sensing head is located above the photosensitive layer and moves in a certain scanning area by moving within a certain scanning area. Scanning and determining the coordinates of the three-dimensional mark in the area and/or the three-dimensional pattern of the three-dimensional mark formed on the wafer area.
  • An exposure beam generating device 300 is arranged above the wafer, and the exposure beam generating device is used to provide the exposure beam required for the exposure of the wafer area, and the exposure beam forms a projection exposure area on the wafer; in addition, the alignment of the present invention
  • the device further includes a displacement driving device 400 for adjusting the relative positions of the exposure beam generating device and the wafer stage according to the three-dimensional mark coordinates measured by the nano-needle tip sensing device, so that the projection exposure area is different from the to-be-exposed area. Expose wafer area alignment.
  • the lithography pattern alignment device shown in FIG. 1 further includes a computer control system 200, and the computer control system 200 is used for receiving the three-dimensional mark coordinates measured by the nano-tip sensing device and comparing the three-dimensional mark coordinates with a reference coordinate, The displacement difference of the two coordinates in the transverse, longitudinal or circumferential direction is obtained, and the displacement difference of the two coordinates in the circumferential direction refers to the displacement difference of the three-dimensional mark in the circumferential direction.
  • the computer control system is used to transmit the displacement difference to the displacement driving device 400, and the displacement driving device 400 causes the exposure beam generating device and/or the wafer stage to move accordingly to reduce the same wafer area The error of the two exposures before and after.
  • the reference coordinates in the present invention are the coordinates of each three-dimensional mark in a certain scanning area pre-stored in the computer control system, or are the coordinates measured by the nano-needle tip sensing device before the three-dimensional mark is exposed to the wafer area.
  • the coordinates are merged with the theoretically horizontal and vertical distances to be moved in order to achieve the alignment of the next wafer area to be exposed with the projection exposure area.
  • the theoretically horizontal and vertical distances to be moved are stored in advance in the scanning area.
  • the three-dimensional mark is a three-dimensional pattern on the surface of the photosensitive layer due to irradiation-induced photosensitive layer degeneration (IIRC)
  • the reference coordinates of the three-dimensional mark are pre-stored for the three-dimensional pattern of the exposed wafer area. Parameters such as graphics and coordinates in the scanning area within the computer control system.
  • the exposure beam emitted by the exposure beam generating device of the present invention is at least one of a light beam, an electron beam, an ion beam or an atomic beam, and the present invention is mainly described by taking an optical lithography machine as an example.
  • FIG. 2 shows a schematic structural diagram of a lithography machine according to a specific embodiment, specifically a schematic diagram of a sub-nanometer step-type repeated exposure optical lithography machine.
  • Its optical lithography machine system is mainly composed of the following parts:
  • the light beam generating device includes a light source 10 , a shutter 20 , a beam shaping system 30 , a beam deflector or mirror 40 , a shaping lens group 50 , a mask work stage 60 and a projection objective lens group 70 .
  • the computer control system 200 of the lithography machine can control the shutter 20 and determine the exposure time of the light source.
  • the wafer table 100 is used for carrying the wafer 110 to be processed.
  • the wafer includes a plurality of wafer regions 120 and a plurality of three-dimensional marks (described in detail later) are set on the wafer.
  • the wafer table 100 includes a moving part and a fixed part, wherein the moving part includes a wafer area switching driving device 105 and a precision moving device 106, and the fixed part 104 of the wafer area switching driving device is located under the wafer area switching driving device 105 for carrying wafers
  • the area switching driving device 105 drives the wafer to move stepwise to expose different wafer areas under the beam generating device in sequence.
  • the computer control system 200 is connected with the wafer area switching driving device 105 which controls the precise movement of the wafer table, and is used for driving the wafer to move step by step to realize the exposure of all wafer areas.
  • the wafer area switching drive device has a large displacement range.
  • the wafer area switching drive device is usually a moving distance above the micron level. At present, the movement of some of the more precise wafer area switching drive devices can be controlled within 10 nanometers to 2.5 nanometers. Positioning accuracy .
  • the precision moving device 106 is located above the fixing device 107, and the fixing device 107 is placed above the wafer area switching drive device 105.
  • the precise moving device 106 can perform sub-nanometer fine-tuning on the position of the wafer in the lateral, longitudinal or circumferential directions.
  • the arrangement of the moving device can reduce the dependence of wafer positioning on the accuracy of the movement of the wafer table, thereby allowing the use of a wafer table with lower moving positioning accuracy.
  • a wafer table with a positioning accuracy of 1 nanometer can be replaced by a wafer table with a positioning accuracy of 1000 nanometers, which greatly reduces the cost of the wafer table.
  • the nano-tip sensing device 90 includes needle-tip sensing heads 91 and 92 and micro-cantilevers 91a and 92a connected to the needle-tip sensing heads.
  • the needle-tip sensing heads are located above the photosensitive layer of the wafer and are used for scanning within a certain scanning area. And determine the coordinates of the three-dimensional mark in the area, and transmit the obtained signal to the computer control system 200 for comparison with the reference coordinates.
  • the nano-tip sensing device can be fixed on a component that is close to the wafer but does not affect the positioning of the exposure beam.
  • the tip sensor head moves with the photon beam, and of course the tip sensor head also drifts with the photon beam.
  • the advantage of this is that the microcantilever of the tip sensing head can be made very short, thereby improving the resolution of the three-dimensional measurement of the tip sensing head surface.
  • the needle tip sensing heads 91 and 92 fixed on the side of the beam projection objective lens group 70 are respectively placed on both sides of the beam projection objective lens group, that is, one or a row on each side, forming a Measurements are made on both sides of the projected exposure area covering the wafer area. That is, each or each row of needle tip sensor heads corresponds to both sides of the wafer area in the projection exposure area, and can measure the off-field three-dimensional marks between wafer areas on both sides of the wafer area.
  • Each or each row of tip sensor heads is fixed on the beam projection objective lens group so that their distance from each other is fixed. Therefore, the mutual coordinates are also fixed.
  • the advantage of setting the tip sensing heads on both sides of the wafer area is that the scanning range of each tip sensing head is greatly reduced, that is, only the middle area of the respective wafer area needs to be scanned, and there is no need to scan the middle area between the wafer areas at one end across the entire wafer area. to the middle of the wafer area on the other side of the wafer area. Thereby, the linearity and positioning accuracy of the scanning of the needle tip sensing head are greatly improved.
  • the displacement driving device 400 includes a wafer area switching driving device 105 and a nano-displacement driving device 420 for driving stepwise switching of the wafer area.
  • the nano-displacement driving device 420 is connected to the computer control system 200, and according to the coordinates of the bottom alignment mark measured by the nano-tip sensing device 90, the position of the light beam generating device and/or the wafer table is controlled to fine-tune, so as to realize the wafer area to be exposed. Align with the exposure beam from the beam generation system and complete the exposure.
  • the nano-displacement driving device 420 can selectively drive at least one of the mirror 40, the shaping lens group 50, the mask plate 60, the projection objective lens group 70 or the wafer stage 100 to move, so as to realize the projection exposure area and Fine-tuned alignment of the wafer area to be exposed.
  • a nano-displacement driving device 61 is installed on the mask work stage 60 to realize the lateral movement of the mask, or a nano-displacement driving device 71 capable of pushing the laterally moving lens is installed around the optical projection objective lens group 70, or the lateral movement Nano-displacement drive means 41 of photon beam/electron beam or deflection means 40 .
  • the position of the projection exposure area can be fine-tuned by arbitrarily selecting one of the above nano-displacement driving devices.
  • more than one nano-displacement driving device can also be arranged on the above-mentioned components.
  • FIG. 3 is a schematic diagram of the position of the preset three-dimensional mark on the wafer.
  • the wafer 110 includes a wafer area 120 exposed to form a three-dimensional pattern and an off-field area 122 disposed on the periphery of the wafer area.
  • the three-dimensional mark can be set in the wafer area, which is called the in-field three-dimensional mark 1201, or it can be set in the off-field area, and the three-dimensional mark is called the off-field three-dimensional mark 1221, and the off-field three-dimensional mark can be set in the adjacent wafer area.
  • the intermediate zone in between or in the wafer edge area.
  • the benefit of off-site 3D marking is that even some destructive processing of these markings does not affect wafer area yield.
  • These marks can be used as alignment marks by photon beam/electron beam exposure, which can be repeatedly "observed", ie exposed, with the photon beam/electron beam.
  • In-field 3D marks 1201 include nanoscale 3D marks that are pre-set before the first processing step in the wafer area, or can be a three-dimensional pattern produced by the photosensitive layer on the wafer after being coated with a photosensitive layer and exposed to the beam on the surface of the wafer area. 3D markers.
  • the three-dimensional mark 1201 in the field can be as small as several nanometers to several hundreds of nanometers, and because it occupies a small area, even if the mark is made in the wafer area, it will not affect the yield problem of the wafer area.
  • the coordinate relationship between these three-dimensional marks and each wafer area can be fixed, and the accurate coordinate position of the wafer area can be located by measuring these three-dimensional marks in the future. Assuming that the wafer is not deformed due to thermal expansion and contraction during a relatively long period of time through precise temperature control, the positioning between these coordinates can easily be accurate to the single nanometer or sub-nanometer level.
  • the first measurement of these 3D marks and the position of the wafer area is to determine the relative deviation of the wafer relative to the wafer table, especially whether the wafer needs to be rotated when the wafer table moves to adjust the wafer table isomorphism
  • the computer control system 200 controls each component of the lithography machine through the off-field 3D marks and the in-field 3D marks in the wafer area and achieves sub-nanometer longitudinal overlay alignment and exposure in the wafer area through a preset control method.
  • Three-dimensional marks 1221 between wafer regions are set between wafer regions. This 3D mark setup is suitable for a step-and-repeat lithography machine. However, for non-mask type direct-writing photon beam/electron beam lithography machines, there are actually many situations in which space is not allowed between the exposed writing fields. Gratings or Fresnel lenses are examples.
  • the present invention utilizes a measurement technology capable of sensing three-dimensional nanoscale structures.
  • a sub-nanometer-level three-dimensional topography measurement technology (sub-nanometer-level atomic force three-dimensional topography measurement technology) can be realized by using a needle tip sensing head sensing technology.
  • a three-dimensional mark is set on the circle, and the three-dimensional mark is measured by the needle tip sensing head sensing technology to realize coordinate positioning.
  • the three-dimensional marks on the photosensitive layer and the wafer surface can be used as alignment marks. For example, by measuring the peak position or recess position of the three-dimensional mark, an accurate alignment coordinate can be determined.
  • the concave-convex structure on the wafer surface generally causes the surface of the photosensitive layer covering it to follow to form a concave-convex structure, that is, the positioning can penetrate vertically, so that the surface covering the photosensitive layer can be measured due to its concave-convex structure.
  • the wafer of the present invention includes a plurality of wafer regions, at least one bottom alignment mark is arranged inside or around the wafer region, a photosensitive layer is provided on the wafer surface, and the bottom alignment mark is located on the photosensitive layer. Corresponding three-dimensional marks are formed on the layer, the three-dimensional marks having regions that are not at the same level as the upper surface of the photosensitive layer.
  • 4A , 4B and 4C respectively illustrate specific embodiments of disposing three-dimensional marks on a wafer.
  • FIG. 4A shows a schematic diagram of a convex three-dimensional mark.
  • one or more bottom alignment mark protrusions 45a (HAMW) are set on the wafer by deposition and other methods, which are the preset nanoscale bottom alignment marks.
  • a photosensitive layer is arranged on the top of the wafer. Since the photosensitive layer has certain fluidity and soft texture, the bottom alignment mark protrusion 45a (HAMW) will form a corresponding protrusion structure 46a (HAMR) on the upper surface of the photosensitive layer. ), the raised structure is the three-dimensional mark of the present invention.
  • the surface layer of the photosensitive layer above the wafer bottom alignment mark 45a will also become a three-dimensional mark.
  • the height of this three-dimensional mark can be correspondingly from several nanometers to several tens of nanometers, usually less than 100 nanometers, which accurately gives its position as a three-dimensional mark on the surface of the photosensitive layer. This position is vertically identical to the position of the vertical lower wafer bottom alignment mark. In this way, we can accurately determine the lateral coordinate of the wafer pattern, it is important that this lateral coordinate can be set within the wafer area (write field).
  • the placement of these three-dimensional marks can determine the accuracy of the alignment so that the alignment does not depend on the accuracy of the wafer table movement. This allows the use of a wafer table with low mobile positioning accuracy. For example, a wafer table with a positioning accuracy of 1 nanometer can be replaced by a wafer table with a positioning accuracy of 1000 nanometers, which greatly reduces the cost of the wafer table.
  • the three-dimensional mark of the present invention and the photosensitive layer have at least some areas on different levels.
  • the three-dimensional mark 46a has a pointed protrusion protruding from the photosensitive layer.
  • the position change of the microcantilever corresponding to each scanning point can be measured by the optical detection method or the tunnel current detection method, so as to obtain the information of the surface topography of the wafer.
  • the three-dimensional mark has a pointed protrusion, and the distance between the pointed protrusion and the needle point sensing head is different from the distance from the upper surface of the photosensitive layer to the needle point sensing head, so that the three-dimensional mark can be accurately scanned by the needle point sensing head. position.
  • the height of the three-dimensional mark set in the present invention is greater than the surface roughness of the photosensitive layer, and an optional height is less than or equal to 50 microns.
  • FIG. 4B shows a schematic structural diagram of the three-dimensional mark on the wafer surface as a concave portion.
  • additional material needs to be added to the wafer.
  • the wafer is etched to form an inverse three-dimensional "protrusion" structure 45b, that is, a recessed structure, which has the advantage of not needing to deposit additional material on the wafer, but "digging" away the material of the existing wafer. , easier than fabricating 3D protruding structures.
  • the photosensitive layer corresponds to the three-dimensional mark 46b formed with a depression.
  • the tip sensing head atomic force microscope can measure the entire three-dimensional structure, even if the pit of the three-dimensional structure is a few nanometers in size at its tip, all the three-dimensional structures of the structure are all three-dimensional. Topographic information can improve localization to the single-nanometer level.
  • FIG. 4C is a schematic diagram of a nanoscale concave-convex three-dimensional mark structure etched on a wafer surface by an etching technology.
  • the advantage is that there is no need to add other materials to deposit on the wafer, and a three-dimensional protruding structure can also be obtained as a nano-scale three-dimensional mark.
  • the three-dimensional mark 46c also has more than one point-like structure, so that the needle tip sensing head can achieve more precise positioning.
  • the three-dimensional mark described in the present invention may optionally have certain graphic features, and the graphic features not only include at least one point-like feature 44, but also include a point-like feature connected to the point-like feature.
  • the ridgeline features 43 are not completely located in the same plane as the upper surface of the photosensitive layer.
  • FIG. 4D shows a schematic diagram of a three-dimensional prismatic structure. The prismatic structure increases the detectable area of the three-dimensional mark and improves the positioning accuracy of the three-dimensional mark by adding several ridgeline features 43 located in different horizontal planes with the photosensitive layer. sex.
  • protruding or concave nano-scale three-dimensional structures such as a miniature cone, a miniature pyramid or a miniature tip sensing head, are preset on the wafer surface. Its diameter scale is from several nanometers to tens of nanometers, usually less than 100 nanometers. These microstructures can be realized by plasma etching techniques or electron beam induced deposition (EBID).
  • EBID electron beam induced deposition
  • a plurality of three-dimensional marks can be set on the wafer.
  • An optional way is that at least one three-dimensional mark is correspondingly set in each wafer area, and the three-dimensional mark can be an in-field three-dimensional mark set inside the wafer area, or The off-site three-dimensional mark arranged around the wafer area, including the off-field area between two laterally adjacent or two longitudinally adjacent wafer areas, or the off-field area corresponding to the edge of the wafer and the wafer area, etc.
  • the coordinates of the three-dimensional mark corresponding to each wafer area are fixed relative to its wafer area.
  • the three-dimensional marks shown in FIGS. 4A-4D described above are three-dimensional marks with absolute positions set on the wafer.
  • the characteristics of the photosensitive layer and the shape of the specific photosensitive layer after exposure can be used to transmit the needle tip.
  • the sensor head sensing technology positions the wafer.
  • the overlay accuracy of the wafer area is improved by the positional positioning of the relative marks.
  • the bottom layer alignment marks described above include the marks made on the surface of the wafer before the first exposure of the wafer, and also the marks placed under the photosensitive layer in the subsequent exposure process.
  • the loss that may occur during the transfer process leads to the weakening of the point-like features and ridgeline features of the three-dimensional mark.
  • the bottom alignment mark can be remade to improve the positioning accuracy of the three-dimensional mark on the surface of the subsequent photosensitive layer.
  • FIG. 5A shows a schematic diagram of an irradiation-induced photosensitive layer modification (IIRC: Irradiation Induced Resist Change) pattern
  • IIRC Irradiation Induced Resist Change
  • the irradiation-induced photosensitive layer modification refers to the position exposed by photon beam or electron beam or other particle beam irradiation
  • the chemical and/or physical properties of the photoactive layer are changed.
  • the chemical changes include photon beam/electron beam-induced chemical reaction on the surface of the photosensitive layer, which causes the irradiated part of the photosensitive layer to change from an insoluble state to dissolve during development (positive glue), or the dissolved state reacts to insoluble (negative glue) through exposure. ).
  • the physical changes of the photosensitive layer also caused by photon beam/electron beam exposure, including the small geometric size changes on the surface of the photosensitive layer, when the photon beam/electron beam exposure transfers the exposure pattern information to the photosensitive layer, the unevenness on the photosensitive layer Structural changes also occur.
  • the exposed area expands on a sub-nanometer or nanometer scale, and relative to the unexposed area 48a, a protruding area 47a is formed, see FIG. 5A; or the exposed area shrinks to form a concave structure, see FIG.
  • the needle tip sensor head sensing technology can realize the positioning of a certain wafer area by measuring the convex area 47a and the concave area 47b. This deformation can be sensed at the sub-nanometer scale by probe tip sensing head (highly sensitive sensing head).
  • the tip sensing head can be used here, for example, a linear array of multiple tip sensing heads can be used to transmit the coordinates of these absolute three-dimensional marks located at the edge of the wafer to the middle of the wafer.
  • the linear tip sensing head array greatly expands the range over which the tip sensing head can measure wafers without error.
  • the mutual distance between the tip sensing heads on the one-dimensional linear tip sensing head array is fixed.
  • the movement of the tip sensing head moves the line array uniformly through the piezoelectric displacement or voice coil drive system at both ends of the line array. Therefore, the relative coordinate positions between the tip sensing heads remain unchanged.
  • a positioning mark generating device (not shown in the figure) can also be provided on the exposure beam generating device, the The positioning mark generating device forms a stereo positioning mark on the periphery of the wafer area when the wafer area is exposed, and the needle tip sensor head performs positioning and calibration on the position of the wafer area to be exposed according to the stereo positioning mark.
  • one or more positioning mark generating devices can be set on the periphery of the normal pattern of the mask plate. When exposing a wafer area to be exposed, a three-dimensional positioning mark is simultaneously exposed at the edge of the wafer area.
  • the positioning marks are optionally located between the two wafer areas, so as to reduce the scanning area of the tip sensing head and improve the positioning efficiency.
  • the computer control system 200 uses the nano-displacement drive device to align the wafer area to be exposed and the projection exposure area according to the coordinates of the stereotaxic mark corresponding to the previous wafer area scanned by the needle tip sensor head. allow.
  • FIG. 6 shows a schematic structural diagram of a lithography machine according to another embodiment of the present invention.
  • the nano-tip sensing device is arranged on the wafer table 100.
  • the wafer table 100 includes a moving part and a fixed part, so The needle tip sensing heads 93 and 94 are connected to the fixed part through the micro-cantilevers 93a and 94a, respectively.
  • the alignment method of this embodiment is to first measure the three-dimensional marks provided between the wafer areas, and/or measure the pattern structure and coordinate position of the wafer area in the wafer area before exposure.
  • the wafer area switching drive device 105 drives the wafer table 110 to move laterally, freeing up the projection exposure area for the next wafer area for exposure, and the movement also brings about a movement error of the writing field.
  • the new coordinate value of the three-dimensional mark on the outside of the wafer area and/or on the inner surface of the wafer area brought about by the movement of the wafer table can be measured by the needle tip sensor head, which can be compared with the coordinate value of the original three-dimensional mark to give the wafer Area Movement Error The amount by which the XY coordinates (and the XY plane angle) should be moved. This amount can be used to reposition the wafer stage or to move objects that affect the photon beam, such as masks or projection objectives, by several nanometers.
  • the sensing technology of the needle tip sensor head is arranged on the wafer worktable, the three-dimensional marks in the wafer edge region can be easily measured. Several 3D markers are required to determine the exact location of the entire wafer.
  • the problem with this method and apparatus is that the size of the wafer table is large, generally more than 200 mm.
  • the microcantilever connecting the tip sensing head and the base of the fixed tip sensing head will be very long.
  • a very long microcantilever may reduce the resolution of the three-dimensional measurement of the surface of the tip sensing head, so this embodiment can be improved.
  • FIG. 7 shows a schematic structural diagram of a photolithography machine according to another embodiment of the present invention.
  • the nano-tip sensing device combines the features of the fixed position in FIGS. 2 and 6 .
  • One set of tip sensing heads 93 and 94 are fixed on the wafer table, and the other set of tip sensing heads 91 and 92 are fixed on one side of the photon beam, such as the two sides of the projection objective lens group.
  • the advantage of this is that the coordinates of the off-site three-dimensional mark corresponding to the area of the wafer to be exposed can be accurately measured, and at the same time, the exact position of the entire wafer can be determined only through several three-dimensional marks.
  • FIG. 8 shows a schematic diagram of the corresponding relationship between multiple needle tip sensing heads and wafer areas according to an embodiment of the present invention, and the coordinate position of each wafer area is measured and determined by the multiple needle tip sensing heads.
  • the plurality of needle tip sensing heads 91 , 92 , . . . 9n are fixedly connected by connecting members 140 , and are arranged in a row laterally according to the distribution of the wafer area to form a lateral needle tip sensing head array.
  • the preparation step at least one bottom layer alignment mark is set on the wafer to be processed, and the bottom layer alignment mark forms a three-dimensional mark correspondingly on the photosensitive layer; when exposing the wafer, the preparation step
  • the wafer with the three-dimensional mark is placed in the above-mentioned lithography machine, and a projection objective lens group 70 is arranged near the wafer in the lithography machine, and the projection objective lens group corresponds to a projection exposure area on the wafer , drive the wafer area switching drive device 105 of the wafer table to place the first wafer area to be exposed under the projection objective lens group; use at least one of the needle tip sensing heads 91-9n to scan the area within a certain scanning area.
  • the photosensitive layer is scanned to obtain the position coordinates of the first three-dimensional mark, such as the three-dimensional mark 1221, and the position coordinates of the first three-dimensional mark are compared with the reference coordinates of the first three-dimensional mark to obtain the difference between the two position coordinates;
  • the displacement driving device adjusts the relative positions of the exposure beam generating device and the wafer stage according to the difference between the two position coordinates, so that the projection exposure area is aligned with the first wafer area, and the beam
  • the generating device emits an exposure beam to the first wafer area of the wafer to realize the exposure of the first wafer area.
  • the reference coordinates of the first three-dimensional mark are pre-stored in the computer control system, and when the three-dimensional mark is located at the reference coordinates, the first wafer area is aligned with the projection exposure area.
  • the second wafer area is placed under the projection objective lens group.
  • the needle tip sensing head scans the moved position coordinates of the first three-dimensional mark and compares it with the moved reference coordinates of the first three-dimensional mark to obtain the deviation of the two position coordinates, and the first three-dimensional mark is moved.
  • the reference coordinates after the movement of the mark are the position coordinates of the first three-dimensional mark when the first wafer area is exposed and the theoretically horizontal and vertical distance of the wafer to be moved in order to align the next wafer area to be exposed with the projection exposure area.
  • the theoretically horizontal and vertical distances to be moved by the wafer are predetermined and stored in the computer system according to parameters such as the size of the wafer area generated by exposure and the distance between two adjacent wafer areas.
  • the positioning of a three-dimensional mark that achieves accurate positioning during the exposure of the previous wafer area after moving one or several steps can accurately determine its reference coordinates according to the number of moved wafer areas.
  • Another alignment method is: after the exposure of the first wafer area is completed, the second wafer area is placed under the projection objective lens group, and the needle tip sensor head scans the position coordinates of the second three-dimensional mark and matches the The reference coordinates of the second three-dimensional mark are compared to obtain the deviation of the two position coordinates, and the displacement driving device adjusts the relative position of the exposure beam generating device and the wafer stage according to the difference of the position coordinates, so that all The projection exposure area is aligned with the second wafer area, and the exposure of the second wafer area is realized, and the reference coordinates of the second three-dimensional mark are stored in the computer control system in advance.
  • the first three-dimensional mark is disposed close to the first wafer area
  • the second three-dimensional mark is disposed close to the second wafer area.
  • the third alignment method is: after the exposure of the first wafer area is completed, the second wafer area is placed under the projection objective lens group, and the needle tip sensing head scans the first wafer area and exposes the photosensitive
  • the graphics and coordinates of the three-dimensional pattern formed on the layer are compared with the reference graphics and coordinates of the three-dimensional pattern pre-stored in the computer control system to obtain the difference between the positions of the two three-dimensional patterns, and the displacement driving device is based on the position coordinates.
  • the difference adjusts the relative positions of the exposure beam generating device and the wafer stage, so that the projection exposure area is aligned with the second wafer area, and the exposure of the second wafer area is achieved.
  • One of the above three alignment methods can be selected according to whether the three-dimensional mark generated by the bottom alignment mark is provided near the wafer area, or two or more alignment methods can be selected to improve the alignment accuracy.
  • more than one three-dimensional mark coordinate can be scanned at the same time and the difference comparison with its corresponding reference coordinate can be performed to improve the alignment accuracy.
  • the third wafer area and subsequent wafer areas are sequentially exposed under the projection objective lens group, and exposure is realized according to the alignment method described above.
  • the nano-needle tip sensing device is fixed on one side or both sides of the projection objective lens group, and is relatively fixed in position with the projection objective lens group.
  • the same 3D mark for alignment, it is necessary to consider the number of needle tip sensing heads and the range of the scanning area. Since the same 3D mark needs to be tracked and scanned, two needle tip sensing heads are optionally arranged on both sides of the wafer area. Coordinate measurement is performed on the 3D mark before exposure and the same 3D mark after the wafer is moved. Another optional method is to select a needle tip sensor head with a larger scanning range to realize tracking scanning of the same 3D mark.
  • the distance between two adjacent tip sensing heads is equal to the sum of the lateral width of one wafer area and the width of the off-field area between the two wafer areas, optional Yes, the distance between two adjacent needle tip sensing heads is a multiple of the sum of the above two distances.
  • This design can ensure that when the wafer areas are exposed sequentially, the needle tip sensing head can scan in a small range to achieve precise positioning of the three-dimensional mark.
  • the positions of the plurality of needle tip sensing heads are relatively fixed with each other through the connecting piece, so as to realize the transfer of the coordinate positioning of a three-dimensional mark on the wafer to the position of other wafer areas on the lateral needle tip sensing head array. At this time, the precise positioning of the wafer coordinates measured by any needle tip sensor head can be transferred to the coordinate positioning measured by other needle tip sensor heads, and there is no error during transmission.
  • the spacing between the tip sensing heads can be greater than or equal to the size of the wafer area plus the distance between the wafer areas, so that one tip sensing head measures the coordinate position of the 3D mark on or near the wafer edge, and the other tip sensing head A three-dimensional mark is measured in the middle between wafer areas, and another tip sensor head measures the middle between wafer areas in another wafer area, and so on.
  • the first tip sensing head measures the position of the three-dimensional mark on the edge of the wafer
  • the lateral tip sensing head array transmits the absolute value of this position to the second tip sensing head, which acts as the second tip sensing head
  • the position of the absolute coordinates can be determined without setting 3D marks on the wafer.
  • the coordinates of the first stylus sensing head can also be transmitted to the inner part of the wafer through the Nth stylus sensing head, and have been transmitted to the last stylus sensing head.
  • the last tip sensor head typically delivers a 3D mark measured to the edge of the other end of the wafer.
  • the wafer area that the tip sensor head cannot move to can transfer the exposure coordinate positioning of several wafer areas through the method of horizontal writing field splicing. Due to the limited number of transfers, the accumulation of excessive positioning coordinate errors can be avoided, thus forming all wafer areas on the wafer. Both overlay positioning can accurately align the exposure scene.
  • the nano-scale three-dimensional mark on the edge of the wafer, or the positioning of the coordinates of the nano-scale three-dimensional mark in the middle of the wafer and the relative position of the beam is realized by the needle tip sensor head array.
  • the needle tip sensor head array To ensure the positioning of the wafer relative to the beam, at least three three-dimensional marks are required. mark. The more spread out the three 3D marks on the wafer, the more accurately the wafer can be positioned.
  • FIG. 9 is an array of multi-tip sensing heads L-shaped tip sensing heads. The array can be positioned using 3D marks at very wide wafer edges as accurate coordinates of the wafer.
  • FIG. 9 is a schematic diagram showing the corresponding relationship between a plurality of needle tip sensing heads and a wafer area according to an embodiment of the present invention.
  • a plurality of needle tip sensing heads are connected by a connector 150 to form an L-shaped array arrangement.
  • the disclosed lateral tip sensing head array of the embodiment shown in 8 adds at least one tip sensing head 101 capable of measuring other rows of three-dimensional marks in the edge region, and the L-shaped array can use the three-dimensional markings of the wafer edges very far apart. The marks are positioned as the exact coordinates of the wafer.
  • FIG. 10 is a schematic diagram showing the corresponding relationship between a plurality of needle tip sensing heads and a wafer area according to an embodiment of the present invention.
  • a plurality of needle tip sensing heads are connected to form a U-shaped array through a connector 160 , as shown in FIG. 8 .
  • at least one needle-tip sensing head 111 capable of measuring other rows of three-dimensional marks in the edge region is respectively added at both ends.
  • the exact coordinate position of the wafer relative to the exposure beam can be determined by three or more nanoscale three-dimensional marks arranged on the edges of both ends of the wafer and separated by more than three distances.
  • the array can be positioned using the 3D marks on both ends of the wafer that are very far apart as the exact coordinates of the wafer.
  • the arms of the U shape can be of different lengths.
  • the linear array of its tip sensing head can be fixed on the beam projection objective lens group or on the wafer table.
  • the needle tip sensing head can measure the wafer surface structure in an atmosphere or a vacuum environment, and can also measure the wafer surface structure by immersing the needle tip sensing head in a liquid in a liquid immersion environment.
  • the three-dimensional mark measured by the needle tip sensor head may be a three-dimensional mark in a liquid immersion environment, or a three-dimensional mark corresponding to the wafer area and the adjacent wafer area in an environment without liquid immersion outside the exposure beam as a three-dimensional marker.
  • the surface structure data of the three-dimensional mark detected by the needle-tip sensing head is the mathematical convolution of the three-dimensional mark surface structure and the needle-tip structure of the needle-tip sensing head, so the shape of the needle-tip sensing head may affect the three-dimensional mark detected by the needle-tip sensing head.
  • the surface structure data of the marker has an impact, so the needle tip sensing head needs to measure and calibrate the needle tip structure before measuring the three-dimensional marker, so as to improve the accuracy of the measurement.
  • the situation described above mainly involves the position adjustment of the wafer in the lateral, longitudinal or circumferential direction to achieve alignment with the projection exposure area.
  • the wafer may deviate from the perpendicularity of the exposure beam, such as it should be horizontal.
  • the set wafer is inclined at a certain angle.
  • three or more needle tip sensing heads can be set, and three or more needle tip sensing heads can be set on different straight lines.
  • three or more needle tip sensing heads measure the 3D marks in their respective scanning areas, it can be determined whether the wafer area where the 3D mark is located is tilted according to the height difference of the identified 3D marks, causing it to transmit with the needle tip.
  • the distance between the sense heads has changed.
  • the wafer table is driven to adjust so that the wafer is perpendicular to the exposure beam.
  • the sub-nanometer-level high-precision lithography wafer area overlay alignment method realized by the alignment device of the present invention includes the following preparatory steps:
  • Step 1 Beam Positioning Preparation.
  • the needle tip sensing head is fixed at the side position of the projection objective lens group of the exposure beam generating device, so the relative position of the needle tip sensing head and the exposure beam is fixed.
  • the coordinate system of the tip sensor head is the coordinate system in which the projected exposure area of the exposure beam undergoes fixed translation.
  • a wafer which can be a wafer with a test structure coated with a photosensitive layer is aligned. Use a mask with a sufficiently fine structure as the calibration mask.
  • IIRC irradiation-induced photosensitive layer degeneration
  • This three-dimensional pattern is the projected coordinate position of the beam on the wafer surface. Measuring the three-dimensional mark outside the wafer area and the IIRC three-dimensional pattern three-dimensional mark in the wafer area with the needle tip sensor head determines the relative fixed coordinate position of the position of the beam projection exposure area and the coordinate position of the needle tip sensor head.
  • the needle tip sensing head is linked together with the coordinates of the projection objective lens group (ie the beam projection pattern).
  • the tip sensor head When using the tip sensor head to measure the positioning of the wafer area, it is like the eyes of the exposure beam to find the exact location of the wafer area.
  • Preparation step 2 Wafer preparation, before or after the wafer is coated with a photosensitive layer, measure the coordinate position of the three-dimensional mark of each wafer area with a needle tip sensor head to determine the mutual position of the coordinates of each off-site three-dimensional mark.
  • Preparation Step 3 Find out the coordinates of the projected exposure area for each wafer area exposure on the first wafer.
  • Method 1 Before the wafer is exposed by photolithography, there is no pattern on the wafer, so there is no alignment problem that the projected exposure area is the same as the pattern left on the wafer that has been exposed last time.
  • the first wafer area pattern area can be formed simply by beam projection exposure, and then the wafer table moves to the next wafer area exposure pattern until all patterns on the wafer are exposed.
  • the off-field 3D mark coordinates of each wafer area by the needle tip sensor head and the intra-field three-dimensional pattern 3D mark coordinates obtained by measuring the photosensitive layer change (IIRC) of the projected exposure area of the wafer area
  • the off-site 3D mark coordinates of the wafer area can be the same as
  • the positional coordinates of the projected exposure area of the wafer area are linked.
  • the position of the projected exposure area can be determined by measuring the coordinates of the three-dimensional mark outside the wafer area.
  • Method 2 After the first exposure of the wafer, after the exposure pattern on the photosensitive layer is transferred to the wafer, such as by plasma etching, directly measure and record the coordinates of the three-dimensional mark outside the wafer area with the wafer area.
  • the three-dimensional pattern marks the coordinate position, so that in the future, as long as the three-dimensional mark coordinates outside the wafer area are measured, the projected exposure area position of the wafer area can be calculated. Measurements can be made through the tip sensing head, or through other measuring instruments than the lithography machine.
  • Prep Step 1 Prep Step 2, and Prep Step 3 are one-offs. After measuring the wafer once at the beginning, the off-site 3D markers can be used to determine the coordinate position of the wafer area.
  • Wafer area coordinate reference point Through the above preparation steps, the wafer area coordinates are associated with the off-site three-dimensional marker coordinates of each wafer area. After determining the coordinates of the three-dimensional mark outside the field, the position coordinates of the wafer area can be determined.
  • Preparation step 4 If there is an angular deviation between the measured array of wafer areas on the wafer and the wafer table that carries the wafer, it is necessary to calibrate the horizontal two-dimensional movement direction of the wafer and the wafer table. Upward angle error. After completing the above preparation steps, start to enter the wafer area overlay alignment step:
  • Alignment Step 1 The first wafer area overlay alignment process begins. Place the wafer 110 coated with the photosensitive layer 120 on the wafer table 100, measure the off-site three-dimensional mark in the wafer area through the needle tip sensor head fixed on the beam projection objective lens group 70, and use the off-site three-dimensional mark obtained in the preparation step 3.
  • the fixed coordinate relationship between the mark coordinates and the pattern area of the wafer area can determine whether the beam is facing the position of the pattern area of the wafer area. Thereby, the coordinate deviation of the position of the beam projection exposure area and the pattern area of the wafer area can be obtained, that is, ( ⁇ X1, ⁇ Y1).
  • Alignment step 2 Using the nano-displacement driving device 61 fixed to the mask plate, the coordinates ( ⁇ X1, ⁇ Y1) obtained in the alignment step 1 are used for the mask plate to make a relative compensation movement corresponding to the error amount. so that the projection exposure area is aligned with the pattern area of the wafer area.
  • Alignment Step 3 Expose the first wafer area within the projection exposure area.
  • Alignment Step 4 Enable the tip sensor head to measure the coordinates of the 3D marks outside the field of the exposed wafer area and the position of the 3D marks in the IIRC stereo pattern in the field; this is equivalent to re-measurement of the coordinate position of the wafer area and the position of the beam projection exposure area, and instant calibration The position of the wafer area and the position of the beam projection exposure area are shown. In this way, even if some parts of the lithography machine drift slightly over time, this step can be used to correct them.
  • Alignment Step 5 Pre-exposure preparation of the second wafer area is performed.
  • the moving wafer table 100 drives the wafer 110 to move laterally, so that the just-exposed first wafer area is moved out of the projection exposure area to become a wafer area with a three-dimensional pattern, and the second wafer area of the subsequent wafer enters the projection exposure area Make room.
  • the movement of the wafer table will bring about positioning errors in the wafer area;
  • Alignment step 6 Start the tip sensor head to measure and identify the off-field 3D mark coordinates corresponding to the second wafer area, the off-field 3D marker coordinates and/or the in-field IIRC associated with the first wafer area moved out of the projection exposure area.
  • the three-dimensional mark coordinates of the three-dimensional pattern are compared to obtain the deviation ( ⁇ X2, ⁇ Y2) that the second wafer area needs to move;
  • Alignment step 7 Using the nano-displacement driving device 61 fixed to the mask plate, according to the coordinates ( ⁇ X2, ⁇ Y2) obtained in the alignment step 6, the mask plate is driven to perform relative compensation movement corresponding to the error amount. So that the beam projection exposure area is aligned with the pattern area under the photosensitive layer of the wafer area.
  • Alignment Step 8 Expose the second wafer area within the projection exposure zone.
  • Alignment step 9 enable the tip sensor head to measure the coordinates of the 3D mark outside the field or/and the position of the 3D mark in the IIRC stereo pattern in the exposed wafer area;
  • Alignment Step 10 Pre-exposure preparation of the third wafer area is performed.
  • the wafer table 100 drives the wafer 110 to move laterally, so that the just-exposed second wafer area is moved out of the projection exposure area to become a wafer area with a three-dimensional pattern, so that the third wafer area of the subsequent wafer enters the projection exposure area. Free space; wafer stage movement can introduce wafer area positioning errors.
  • Alignment Step 11 Activate the tip sensor head to measure and identify the coordinates of the off-field 3D mark associated with the third wafer area and measure the above-mentioned 3D mark of the 3D pattern in the second wafer area moved out of the projection exposure area, and the above-mentioned move out Comparing the off-field three-dimensional mark coordinates related to the first wafer area in the projection exposure area and/or the three-dimensional pattern three-dimensional mark coordinates of the IIRC in the field to obtain the deviation ( ⁇ X3, ⁇ Y3) that the second wafer area needs to move;
  • Alignment step 12 Using the nano-displacement driving device 61 fixed to the mask plate, according to the coordinates ( ⁇ X3, ⁇ Y3) obtained in the alignment step 11, the mask plate is driven to perform relative compensation movement corresponding to the error amount. So that the beam projection exposure area is aligned with the pattern position of the wafer area.
  • Alignment step 13 Repeat the cycle to complete the exposure, movement and overlay of the entire wafer area.
  • the three-dimensional mark used for alignment described in this embodiment can not only be selected from the off-site three-dimensional mark in the middle between the wafer area waiting to be exposed and the adjacent wafer area, but also can be selected from the surface of the previously exposed wafer area (which has been coated with The IIRC three-dimensional mark of the photosensitive layer) is used as the coordinate reference system for the exposure of the next wafer area. Since there is no need to set 3D marks between wafer areas using IIRC, the setting of 3D marks between wafer areas can be greatly reduced. However, using the IIRC three-dimensional pattern 3D mark as the coordinate system of the last exposed wafer area will lead to the accumulation of errors caused by the needle tip sensor head measuring each exposed wafer area.
  • the wafer area with corresponding 3D marks and the wafer area without corresponding off-site 3D marks are set at intervals, and several wafer areas are saved by using several IIRC graphics as the reference points for the alignment and positioning of the projection exposure area.
  • the off-site 3D marking between the two while ensuring that the accumulated total error is within the allowable range.
  • the linear array with multiple needle tip sensing heads is combined with the off-site 3D markers in the wafer area and the IIRC 3D markers in the wafer area, so that a smaller number of off-site 3D markers can be set quantity.
  • the horizontal needle-tip sensing head array directly binds the movement error between the first needle-tip sensing head and other needle-tip sensing heads fixed on the needle-tip sensing head linear array to the position of the first needle-tip sensing head, Spanning multiple wafer regions in between may accumulate errors due to the failure to use the three-dimensional markings in the middle between adjacent wafer regions to confirm the positioning of the wafer regions.
  • nano-scale three-dimensional marks can be set only on the edge of the wafer, and then a linear array of needle-tip sensing heads is used to directly connect the coordinate position inside the wafer to the edge of the wafer through the linear sensing head array.
  • a linear array of needle-tip sensing heads is used to directly connect the coordinate position inside the wafer to the edge of the wafer through the linear sensing head array.
  • the error accumulation caused by the exposure of multiple wafer areas in the middle before and after exposure and referring to the exposure of the previous wafer area is eliminated.
  • the present invention is mainly achieved through the following technical solutions:
  • tip sensing head sensing technology including tip sensing head atomic force microscopy.
  • Atomic force microscopy is one of the sensing technologies of the tip sensing head. It can measure the three-dimensional surface topography of the wafer with sub-nanometer precision, as well as the nanoscale distribution of surface work function.
  • the first technology is piezoelectric ceramic technology that moves in sub-nanometer steps.
  • Sub-nanometer movement can be generated using piezoelectric principles.
  • general piezoelectric motions are nonlinear and have hysteresis loops.
  • the second technology is electromagnetic drive technology.
  • Voice coil motor (Voice Coil Motor) is a special form of direct drive motor. It has the characteristics of simple structure, small volume, high speed, high acceleration and fast response. Its positioning accuracy can reach the order of 1/30 nanometer. It works by placing an energized coil (conductor) in a magnetic field to generate a force proportional to the current applied to the coil.
  • the motion form of the voice coil motor manufactured based on this principle can be a straight line or an arc. Both techniques can be used in the present invention.
  • sub-nanometer positioning can be achieved.
  • This positioning is to make nanometer-level positioning and displacement adjustment of the wafer area/writing field of the wafer relative to the photon beam/electron beam, so as to eliminate the relative coordinate offset caused by the movement of the wafer table or the photon beam/electron beam movement.
  • various methods and devices for correcting the position errors of the wafer area/writing field relative to the photon beam/electron beam position deviation can be provided, so as to realize the lateral splicing and vertical nesting of the sub-nanometer wafer area/writing field Align.
  • a wafer stage with sub-nanometer positioning can be used, or a more precise picometer-scale small wafer stage can be set up on the existing wafer stage to make Precise positioning, i.e. smaller steps than existing wafer tables. (The small wafer stage can move slower).
  • a driving device that drives the nanoscale movement of the mask workpiece table can be set, and the nanoscale movement of the photon beam/electron beam projection objective lens group can be set to drive the nanoscale movement of the photon beam/electron beam projection objective lens group, which is enough to realize the wafer area. / Correction of the alignment error of the write field.
  • the displacement of the photon beam/electron beam projection objective lens group can be set to move, and the lens can be moved by several or tens of nanometers, which is enough to realize its relative writing field/wafer area. Correction of alignment errors.
  • the driving photon beam/electron beam itself or the deflection device can be set to realize the displacement and coordinate correction of photon beam and electron beam.
  • An apparatus and method for closed-loop controlled measurement and alignment and exposure of wafer areas in a lithography machine are provided.
  • the lithography machine alignment system disclosed by the invention has the closed-loop control characteristics of measurement-movement-re-measurement of wafer area overlay alignment, and the specific overlay alignment method for the wafer area of the ultra-high-precision lithography system is as follows:
  • Method 1 Use the off-site three-dimensional mark 1221 as the reference point for alignment and positioning of the wafer area, such as the coordinate position of the three-dimensional protruding (concave) mark between the wafer areas or the edge of the wafer, that is, measure the pattern of the wafer area with the needle tip sensor head (the coordinate position of each wafer area pattern on the wafer and the three-dimensional protruding (concave) mark on the wafer and its relative coordinate position are determined in advance, and are not affected by the movement of the wafer table and the deviation of the beam).
  • the coordinate position of the three-dimensional protruding (concave) mark between the wafer areas or the edge of the wafer that is, measure the pattern of the wafer area with the needle tip sensor head (the coordinate position of each wafer area pattern on the wafer and the three-dimensional protruding (concave) mark on the wafer and its relative coordinate position are determined in advance, and are not affected by the movement of the wafer table and the deviation of the beam).
  • This coordinate difference can be used to drive the exposure beam generating device such as a mask to perform nanoscale horizontal movement for compensation, and can also set the nanoscale horizontal movement of the driving photon beam/electron beam projection objective lens group, and can also set the driving photon beam/electron beam itself or
  • the nanoscale horizontal movement of the deflection mirror can also be set up to drive the wafer stage or a piezoelectric wafer stage with a smaller step size installed on the wafer stage, which is sufficient to correct the alignment error of the wafer area/writing field .
  • Method 2 The three-dimensional pattern formed by irradiation-induced photosensitive layer modification (IIRC) after the exposure of the first wafer area, as shown in Figures 5A and 5B, is used as the alignment position coordinates of the next wafer area.
  • the corresponding three-dimensional mark may not be set in the wafer area to be exposed, that is, no three-dimensional mark is set in the wafer area or around the wafer area.
  • the three-dimensional mark of the three-dimensional pattern formed on the wafer area determines the boundary of the wafer area, and then determines whether the next wafer area to be exposed needs to be fine-tuned for nanoscale displacement and the deviation of the adjustment.
  • Method 3 This method is set in combination with method 1 and method 2 above. Considering that a preferred embodiment of the method is to set three-dimensional marks on each wafer area, since there are many wafer areas on a wafer, a considerable number of bottom alignment marks need to be fabricated on the wafer in advance. However, in the second method, using the exposure three-dimensional pattern three-dimensional mark of the previous wafer area for positioning may have the problem of accumulated error, so this method combines the method one and the second method, and the corresponding three-dimensional mark is set in the wafer area and no three-dimensional mark is set.
  • the wafer area is set at intervals, that is, the three-dimensional mark corresponding to the wafer area is used as the absolute reference point to realize the exposure overlay alignment of the first wafer area, and then the irradiation-induced photosensitive layer modification (IIRC) exposed in the wafer area is used as the lateral
  • the alignment coordinates of the wafer area are transferred to the alignment and exposure of the next wafer area.
  • the 3D mark corresponding to the wafer area is obtained as the absolute overlay alignment mark and restarted Absolute exposure alignment for the next batch of wafer areas. In this way, while ensuring the overlay accuracy of all wafer areas, the setting amount of the bottom alignment marks on the wafer is greatly reduced.
  • the invention is suitable for deep ultraviolet and extreme ultraviolet optical lithography machines, and solves the problem that the photon beam cannot be used to directly face the wafer coated with the photosensitive layer for alignment measurement before exposure, and the wafer area can only be positioned by the movement of the wafer table technical difficulties.
  • the technical solutions disclosed in the present invention do not generate cumulative errors. Therefore, it is avoided that the wafer table must return to the origin every time and move to the specified position with the origin as the absolute reference point, which will greatly improve the working speed.
  • the present invention also solves the problem that even if the wafer table is positioned accurately, the photon beam will drift due to the drift of the projection objective lens group of the photon beam and the mask (through various factors such as thermal expansion and contraction), resulting in the final photon beam of the photon beam. Alignment with wafers complicates technical issues.
  • the above methods are based on the closed-loop control principle of the relative position between the wafer and the exposure beam to perform the wafer area overlay alignment.
  • This alignment mechanism is more precise than a precise wafer table. Because even if the wafer stage is temporarily positioned accurately, the drift of the beam on the wafer is difficult to compensate for the wafer stage, and it is also difficult for the laser interferometer to align between the wafer and the beam.

Abstract

一种步进式光刻机、其工作方法及光刻图形对准装置，其中，在晶圆（110）上设置若干三维标记（1201,1221），以此作为晶圆（110）表面定位的坐标预设，利用针尖传感头（91,92,93,93…9n,101,111）传感技术测量三维标记（1201,1221）获得晶圆（110）表面亚纳米精度的坐标，然后移动晶圆工作台（100），测得晶圆工作台（100）移动后的三维标记（1201,1221）的新坐标并同晶圆工作台（100）移动前同样的三维纳米坐标比较得出晶片区域（120）位置坐标误差值。利用闭环控制原理将坐标误差通过移动曝光束发生装置（300）同晶片区域（120）的相对位置进行补偿，实现相对坐标位置的重新精确对准。这种光刻图形对准装置可以应用在使用掩模板的深紫外和极紫外光学光刻机，也可以应用在电子束/光子束直写式光刻机的亚纳米级晶片区域或写场横向和纵向对准拼接应用场景。

Description

一种步进式光刻机、其工作方法及图形对准装置 技术领域
本发明涉及光刻技术领域，尤其涉及光刻图形的套刻对准和定位技术领域。
背景技术
微电子学和光电子学的发展引起了集成电路芯片、集成光学芯片的高速发展。这些产业成为现代计算机、显示屏乃至整个信息产业核心器件和芯片的基础。当前，现代芯片工业的技术节点已经达到了5纳米甚至更小。
制造芯片这样的微纳米器件离不开光刻技术。光刻技术包括普通光学光刻技术，深紫外/极紫外光刻技术，电子束光刻技术、离子束光刻技术等。借助这些关键光刻技术才能制造出精细的光刻图形以至包罗万象的微纳米器件结构，例如集成电路芯片和光电集成芯片。
现有的光学光刻系统，包括深紫外光学光刻机和极紫外光学光刻机已经广泛地应用于工业型芯片制造和MEMS制造等领域。由于晶圆越来越大，目前12英寸直径的晶圆已经普及，正在朝着更大尺寸的晶圆发展。任何系统都无法一次性将整个晶圆曝光。一般的做法是依次曝光晶圆上的一个一个晶片区域(DIE)。一个晶片区域曝光完毕后，晶圆通过晶圆工作台的移动，移动到近邻的下一个晶片区域并进行套刻对准，而后曝光。这里对准是指本次曝光的图形必须同晶片区域上的已经有的图形垂直对准(即套刻对准)以后才能进行本次的光刻曝光。其对准的精度即套刻精度至少不能亚于晶片区域上电路图形的最小尺寸数倍。该尺寸目前在5-10纳米左右。用于制作掩模板的多束电子束光刻机比如奥地利高科技公司IMS公司MBMW-101系列，可以用于5纳米节点掩模板制作，其套刻对准精度在5纳米以下。荷兰极紫外光学光刻机ASML公司的光刻机系列TWINSCAN3400B和4300C用于5纳米技术节点，其套刻精度分别为2.5纳米和1.5纳米。下一步芯片结构尺寸就要进入3纳米数量级。所以面对晶片区域曝光的光刻机的套刻对准定位精度必须要求在1纳米或者1纳米以下。面对这么高要求的晶片区域的套刻精度，目前没有相关的定位技术，所以新技术必须发明出来。
对晶圆工作台定位精度极高的要求难以实现还来源于光刻工艺的一个特点，也是一个巨大的缺点，即是晶圆在曝光前涂布了一层光敏层在晶圆上。在光刻技术中，光刻图形将通过曝光被转移到光敏层，然后光敏层上的光刻图形通过刻蚀工艺转移至晶 圆。需要注意的是晶圆上的光敏层作为覆盖晶圆的上表面，这个上表面由于“怕光”使得电子束或光子束无法在曝光前通过辐照(即是曝光)来作表面观察，更无法穿透光敏层获得光敏层下面的晶圆的图形。所以即将曝光的图形无法同光敏层下面晶片区域图形形成套刻对准，即光刻机只能“盲人操作”，移动晶圆工作台然后光束“盲人操作”曝光。导致晶圆曝光的定位不准确，套刻误差较大。
发明内容
为了解决上述技术问题，本发明提供一种光刻图形对准装置，所述装置位于一光刻机机体内，包括：
一晶圆工作台，用于承载待处理晶圆，所述晶圆包括若干晶片区域和晶片区域外围的场外区域，所述晶圆表面设置光敏层，所述光敏层设有三维标记，所述三维标记具有与所述光敏层的上表面不在同一水平面的区域；
纳米针尖传感装置，包括一针尖传感头，所述针尖传感头位于所述光敏层的上方，用于在扫描区域内移动扫描并确定该扫描区域内三维标记的坐标；
曝光束发生装置，用于提供晶片区域曝光所需的曝光束，并在所述光敏层上形成投影曝光区；
位移驱动装置，用于根据所述针尖传感头测得的三维标记坐标调整所述曝光束发生装置和所述晶圆工作台的相对位置，使得所述投影曝光区与待曝光晶片区域对准。
可选的，所述装置还包括一计算机控制系统，所述计算机控制系统用于接收纳米针尖传感装置测得的三维标记坐标并与该三维标记的基准坐标进行比较，得到两个坐标的差值，所述计算机控制系统用于将该差值传递至所述位移驱动装置，并控制所述曝光束发生装置和/或所述晶圆工作台相互移动以补偿所述差值。
可选的，所述基准坐标为所述三维标记预设的位置坐标，当所述三维标记位于该预设位置时，待曝光晶片区域与所述投影曝光区对准，所述基准坐标预先存储于所述计算机控制系统内。
可选的，所述基准坐标为所述纳米针尖传感装置对所述三维标记在该晶片区域曝光前测得的坐标与为实现下一片需要曝光的晶片区域与投影曝光区对准理论上晶圆要移动的距离合并后在所述扫描区域内对应的坐标，理论上晶圆在横向和纵向要移动的距离预先存储于所述计算机控制系统内。
可选的，所述光敏层上的三维标记包括设置在光敏层下方的底层对准标记在光敏层上对应形成的三维标记和/或由曝光束在光敏层表面曝光后形成的辐照诱导光敏层改性(IIRC)形成的三维立体图案。
可选的，所述底层对准标记在光敏层上对应形成的三维标记位于所述晶片区域内或者相邻晶片区域之间的场外区域内。
可选的，所述底层对准标记包括在晶圆第一次曝光前制作到晶圆衬底表面上的标记和/或在后续曝光工序中设置在所述光敏层下方的标记。
可选的，所述三维标记的高度大于所述光敏层的表面粗糙度。
可选的，所述三维标记的坐标包括晶圆的横向位置坐标、纵向位置坐标以及周向位置坐标。三维标记的周向位置坐标指三维标记在圆周方向的坐标，即三维标记的图形在圆周方向上的角度坐标。
可选的，所述光敏层上设置两个或两个以上三维标记。
可选的，所述三维标记具有一定的图形特征，所述图形特征包括至少一个点状特征，所述点状特征与所述光敏层的上表面位于不同的水平面内。
可选的，所述图形特征还包括与所述点状特征相连的棱线特征，所述棱线特征与所述光敏层的上表面不完全位于同一平面内。
可选的，所述三维标记为凸出于或凹陷于所述光敏层上表面的立体结构。
可选的，所述立体结构为锥形结构、多边棱形结构、金字塔形结构中的至少一种。
可选的，每个晶片区域对应至少一个三维标记，所述三维标记位于所述晶片区域内或该晶片区域周围的场外区域内，所述三维标记的基准坐标预先存储于计算机控制系统内。
可选的，部分晶片区域未设置对应的三维标记，该晶片区域根据针尖传感头测得的前一个完成曝光的晶片区域内的立体图案三维标记实现与所述投影曝光区对准。
可选的，未设置对应三维标记的晶片区域与设置有对应三维标记的晶片区域间隔设置。
可选的，所述曝光束发生装置上设置定位标记发生装置，所述定位标记发生装置在晶片区域曝光的同时在晶圆区域外围形成一立体定位标记，针尖传感头根据该立体定位标记对待曝光晶片区域的位置进行定位校准。
可选的，所述三维标记的高度小于等于50微米。
可选的，所述针尖传感头为主动式原子力针尖传感头、激光反射式原子力针尖传感头、隧道电子探针传感头或纳米级表面功函数测量传感头中的一种或多种的组合。
可选的，所述针尖传感头在大气或真空环境下测量晶圆表面结构，或在浸液环境下将针尖传感头浸入液体中测量晶圆表面结构。
可选的，对于浸液式光刻，所述三维标记为浸液环境中的三维标记，或者晶片区域同曝光束之外没有浸液环境中相邻晶片区域对应的三维标记。
可选的，所述针尖传感头所测的三维标记的表面结构数据是所述三维标记表面结构同所述针尖传感头的针尖结构的数学卷积，所述针尖传感头在对三维标记进行测量前进行所述针尖结构的测量和校准。
可选的，所述纳米针尖传感装置还包括微悬臂，所述微悬臂一端固定，一端设置所述针尖传感头。
可选的，所述纳米针尖传感装置包括一个或一个以上的针尖传感头，所述针尖传感头通过所述微悬臂固定在所述曝光束发生装置的一侧或两侧。
可选的，所述曝光束发生装置包括设置在所述晶圆上方的投影物镜组，所述一个或一个以上的针尖传感头通过微悬臂固定在所述投影物镜组的一侧或两侧。
可选的，所述晶圆工作台包括移动部分和固定部分，所述针尖传感头通过所述微悬臂与所述固定部分相连接。
可选的，所述纳米针尖传感装置包括两个或两个以上的针尖传感头，其中一个或一个以上的所述针尖传感头固定在所述晶圆工作台的固定部分上，一个或一个以上的所述针尖传感头固定在所述曝光束发生装置的侧边。
可选的，所述纳米针尖传感装置包括两个或两个以上的针尖传感头，若干所述针尖传感头通过一连接件固定在所述曝光束发生装置的一侧或两侧，若干所述针尖传感头之间的相对距离固定。
可选的，所述纳米针尖传感装置包括三个或者三个以上的针尖传感头，所述针尖传感头通过连接件固定在晶圆工作台的固定部分上和/或通过连接件固定在曝光束发生装置上，所述针尖传感头位于不同直线上，以确定晶圆同曝光束之间是否垂直。
可选的，每个所述针尖传感头测试其位置对应的晶圆表面或者光敏层表面到曝光束发生装置的距离，根据测得的距离相同与否判断晶圆与曝光束是否垂直，并通过计算机控制系统驱动所述晶圆工作台调节至所述晶圆同曝光束垂直。
可选的，所述纳米针尖传感装置包括多个通过连接件固定的针尖传感头，所述多个针尖传感头根据所述晶片区域的分布横向设为一排，形成一横向针尖传感头阵列。
可选的，所述横向针尖传感头阵列一端设置纵向分布的至少一针尖传感头，形成一L形针尖传感头阵列。
可选的，所述横向针尖传感头阵列两端分别设置纵向分布的针尖传感头，形成一U形针尖传感头阵列。
可选的，所述相邻两针尖传感头之间的距离大于等于一个晶片区域的横向宽度。
可选的，所述位移驱动装置包括晶片区域切换驱动装置和纳米位移驱动装置。
可选的，所述晶片区域切换驱动装置与所述晶圆工作台的移动部分相连，用于带动待曝光晶片区域依次暴露于所述投影曝光区下方。
可选的，所述晶圆工作台的移动部分还包括精密移动装置，所述纳米位移驱动装置为所述精密移动装置。
可选的，所述纳米位移驱动装置与所述曝光束发生装置和/或所述晶圆工作台的精密移动装置相连，用于控制所述曝光束发生装置和/或所述晶圆工作台在横向和/或纵向和/或周向移动。
可选的，所述纳米位移驱动装置驱动所述曝光束发生装置和/或所述精密移动装置移动的工作原理为压电原理、音圈驱动原理或者电磁驱动原理中的至少一种。
可选的，所述曝光束发生装置发出的曝光束为光束、电子束、离子束或原子束的至少一种。
可选的，所述曝光束发生装置为光束发生装置，所述光束发生装置包括光源、光闸、光束偏转片/反射镜，掩模板和投影物镜组，所述纳米位移驱动装置与所述光束偏转片/反射镜，所述掩模板和所述投影物镜组的至少之一相连，以调整所述光束发生装置的投影曝光区位置。
可选的，所述至少一针尖传感头固定在所述投影物镜组的至少一侧。
可选的，所述光束为平行光束或者高斯型光束。
可选的，所述光束的整形、聚焦系统可以由光学透镜组成，也可以由光学反射镜组成。
可选的，所述晶圆包括完整晶圆、部分晶圆，或者需要光刻曝光处理的非晶圆物质。
进一步的，本发明还公开了一种步进式光刻机，用于对晶圆内多个晶片区域实现重复曝光，所述光刻机内设置如上文所述的光刻图形对准装置。
进一步的，本发明还公开了一种步进式光刻机的工作方法，所述方法包括：
准备步骤，在晶圆上设置至少一底层对准标记，并在所述待处理晶圆上涂覆光敏层，所述底层对准标记在所述光敏层上对应形成三维标记；
对准步骤，将准备步骤中设有三维标记的晶圆置于上文所述的光刻机内，所述光刻机内靠近晶圆设置一投影物镜组，所述投影物镜组在晶圆上对应一投影曝光区，驱动所述晶圆工作台将待曝光的第一晶片区域置于所述投影物镜组下方；利用所述针尖传感头在一定扫描区域内对光敏层进行扫描，获得第一三维标记的位置坐标，将所述第一三维标记的位置坐标与该第一三维标记的基准坐标比较，获得两个位置坐标的差值；所述位移驱动装置根据两个位置坐标的差值调整所述曝光束发生装置和所述晶圆工作台的相对位置，使得所述投影曝光区与所述第一晶片区域对准；
曝光步骤，所述光束发生装置发出曝光束到所述晶圆的第一晶片区域，实现所述第一晶片区域的曝光。
可选的，完成第一晶片区域的曝光后，将所述第二晶片区域置于所述投影物镜组的下方，所述针尖传感头扫描所述第一三维标记移动后的位置坐标并与该第一三维标记移动后的基准坐标进行比较得到两个位置坐标的偏差，所述位移驱动装置根据所述位置坐标的差值调整所述曝光束发生装置和所述晶圆工作台的相对位置，使得所述投影曝光区与所述第二晶片区域对准，并实现所述第二晶片区域的曝光。
可选的，所述第一三维标记移动后的基准坐标为第一晶片区域曝光时所述第一三维标记的位置坐标与为实现下一片需要曝光的晶片区域与投影曝光区对准，晶圆理论上横向和纵向要移动的距离合并后在所述扫描区域内对应的坐标。
可选的，所述投影物镜组两侧分别设置至少一所述针尖传感头，或者所述投影物镜组一侧设置一针尖传感头，且所述针尖传感头的扫描宽度大于一待曝光晶片区域的宽度。
可选的，完成第一晶片区域的曝光后，将所述第二晶片区域置于所述投影物镜组的下方，所述针尖传感头扫描第二三维标记位置坐标并与该第二三维标记的基准坐标进行比较得到两个位置坐标的偏差，所述位移驱动装置根据所述位置坐标的差值调整所述曝光束发生装置和所述晶圆工作台的相对位置，使得所述投影曝光区与所述第二 晶片区域对准，并实现所述第二晶片区域的曝光，所述第二个三维标记的基准坐标预先存储于所述计算机控制系统内。
可选的，所述第一三维标记靠近所述第一晶片区域设置，和/或所述第二三维标记靠近所述第二晶片区域设置。
可选的，完成第一晶片区域的曝光后，将所述第二晶片区域置于所述投影物镜组的下方，所述针尖传感头扫描所述第一晶片区域曝光后光敏层上形成的立体图案的图形和坐标并与该立体图案预设的图形和坐标进行比较得到两个立体图案位置的差值，所述位移驱动装置根据所述位置坐标的差值调整所述曝光束发生装置和所述晶圆工作台的相对位置，使得所述投影曝光区与所述第二晶片区域对准，并实现所述第二晶片区域的曝光。
可选的，所述纳米针尖传感装置固定在所述投影物镜组的一侧或两侧，并与所述投影物镜组之间的位置相对固定。
本发明的光刻图形对准装置可以针对的光刻技术是深紫外和极紫外光刻机等，例如是紫外步进式重复曝光光刻机(Stepper)。其特点是光束通过掩模板形成曝光图形，辐照到涂附光敏层的晶圆上。每次对准和曝光一个晶片区域，通过晶圆工作台的移动去对准和曝光另一个晶片区域，最后把晶圆上的晶片区域全部曝光完毕。当然本发明同样可以适用于电子束/光子束直写的光刻机。
本发明在晶圆表面设置三维标记，通过对晶圆的一次测量，即可把这些三维标记同各个晶片区域的坐标关系固定下来，以至于以后只要测量这些三维标记即可定位晶片区域的准确坐标位置。如果晶圆在比较长的时间段内通过精确的温度控制没有由于热胀冷缩等原因产生形变，这些坐标间的定位可以容易地精确到单纳米级。
第一次测量这些三维标记以及晶片区域的位置，即是测定了晶圆相对于晶圆工作台的相对偏差，尤其是晶圆工作台移动时晶圆是否需要转动来调整晶圆工作台移动同晶圆上晶片区域阵列的平行度。
不同于电子束可以通过扫描电子显微镜来观察和测量晶圆表面的图形，光子束光刻机(深紫外光刻机和极紫外光刻机)由于所用曝光的光子波长不允许其对晶圆图形的测量达到纳米级的分辨率，所以光子束无法参与单纳米及其以下尺寸精度的对准定位。而利用本发明的技术方案可以使得光子束光刻机的定位准确度到纳米及亚纳米级别。
三维标记离正要曝光的晶片区域越近，则用于晶片区域的对准精度越高。三维标记设定在晶片区域之间或者晶片区域内部，这个对于步进式重复曝光光刻机就属于这种类型。假如设置在晶片区域内部的三维标记能做到小至几个纳米到几百个纳米，由于其占用的面积很小就会非常实用，则即使在晶片区域内制作三维标记也不会影响到晶片区域成品率问题。
本发明采用能够感知三维纳米级结构的测量技术，比如使用针尖传感头传感技术实现亚纳米级的三维形貌测量技术(亚纳米级的原子力三维形貌测量技术)，则纳米级的三维标记可以通过针尖传感头传感技术测量而起到纳米级坐标作用。在光敏层和晶圆表面的三维标记可以用来作为对准标记，比如测量三维标记的峰值位置或者凹处位置，就可以确定一个精准的对准坐标。晶圆表面的凹凸结构一般都会引起覆盖其上面的光敏层表面跟随形成凹凸结构，即定位能够垂直穿透，这样覆盖光敏层的表面由于其凹凸结构和位置就可以被测量到。本发明采用的针尖传感头传感技术可以使得光学测量达到亚纳米级的测量。
本发明除了可以采用上文描述的三维标记对晶圆进行定位，还可以根据辐照诱导光敏层改性的特点进行晶片区域曝光的定位，辐照诱导光敏层改性(IIRC：Irradiation Induced Resist Change)指的是在光子束或者电子束或者其他粒子束辐照曝光的位置，光敏层的化学和/或物理特性产生了变化。化学变化包括光子束/电子束引起光敏层表面化学反应，导致被辐照的光敏层部分从不溶解的状态变化为显影时溶解(正胶)，或者溶解状态通过曝光反应成不能溶解(负胶)。光子束/电子束曝光也会引起的光敏层的物理变化，包括光敏层表面微小的几何尺寸的变化，比如在亚纳米量级或纳米量级上膨胀或者萎缩形成凹凸结构。当光子束/电子束曝光将曝光图形信息转移到光敏层上时，光敏层上的凹凸结构变化也就产生了。这种变形可以通过针尖传感头(高度敏感传感头)在亚纳米尺度上探测而感知。
本发明的优点在于：
1、为光刻机提供一种全新的能以亚纳米级精度测量晶片区域图形实际位置的技术；
2、提供多种纠正曝光光子束/电子束坐标位置相对于晶片区域/写场坐标位置之间纳米级移动的方法和装置；
3、提供一种晶片区域超高套刻对准精度的(极)紫外光学光刻机；
4、提供光刻机中以闭环控制原理的晶片区域/写场的组合式横向和纵向对准拼接误差矫正然后曝光的方法和装置。
附图说明
为了更清楚地说明本发明的技术方案，下面将本发明技术方案描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，根据这些附图示出的发明构思获得其他的实施方式均属于本发明保护的范围。
图1示出本发明一种光刻图形的对准装置示意图。
图2示出一种具体实施方式的光刻机结构示意图。
图3示出三维标记在晶圆上的位置示意图。
图4A为表面凸出三维标记示意图；图4B为表面凹陷三维标记示意图；图4C为表面凹凸型三维标记示意图，图4D为一种三维标记的立体结构示意图。
图5A为辐照诱导光敏层膨胀结构示意图；图5B为辐照诱导光敏层收缩结构示意图。
图6示出本发明另一实施例的光刻机结构示意图。
图7示出本发明另一实施例的光刻机结构示意图。
图8示出本发明一种实施例的多个针尖传感头及晶片区域对应关系的示意图。
图9示出了本发明另一种实施例的针尖传感头及晶片区域对应关系的示意图。
图10示出了本发明另一种实施例的针尖传感头及晶片区域对应关系的示意图。
具体实施方式
下文将结合附图对本发明的发明构思和技术方案进行详细说明。
在步进式重复曝光光刻机领域，一个晶片区域曝光完毕后，晶圆通过晶圆工作台的移动，移动到下一片晶片区域进行套刻对准，而后曝光。目前光刻机的对准主要通过晶圆工作台的精确定位来实现晶圆上的晶片区域同光束投影曝光区的对准。这种对准会带来晶圆工作台移动引起的定位误差。而且不能及时矫正光束偏移带来的对准误差。整个定位过程属于定位前没有坐标测量，定位后也没有坐标测量的开环控制状态。没有实时测量对准误差以及利用对准误差的反馈信息。这个误差一般在几个纳米甚至至几十个纳米。
激光晶圆工作台的精度可以通过激光干涉的光波长的高次方处理获得几个纳米的精度。晶圆工作台的驱动装置可以是压电驱动模式甚至是音圈驱动模式等模式。其移动定位精度可以到亚纳米级甚至皮米级。问题是激光干涉测量出来的位置是光程的距 离，并不一定是实际晶圆工作台真正需要移动的距离。只要晶圆工作台或者光束周围有一点点微小的温度变化，空气浓度和气压的变化都会引起光程差和实际距离的不一致，从而使得激光测得的距离并非晶圆工作台需要移动的实际距离。而且激光晶圆工作台的多次移动会积累每次移动的误差，从而放大误差。本发明人研究发现：要测量单纳米以及亚纳米的精度，即使使用最精确的激光干涉矫正机制也是非常困难的，即使矫正成功也是偶然的。
此外，研究发现，某些深紫外和极紫外光学光刻机，其晶圆同曝光光束之间有激光干涉定位机制，即形成晶圆一边同产生曝光光束相连的光刻机部分，这一边通过激光干涉形成相互定位。这是一种闭环控制系统。在晶片区域上，晶片区域的中间地带设置了光栅结构。激光从曝光光束相连的光刻机部件发射到晶片区域间中间地带的光栅结构上，然后返回到曝光光束相连的光刻机部件方，同发射激光形成干涉，或者同曝光光束一边的光栅形成双光栅干涉。干涉条纹的移动即对应晶片区域同曝光光束间的相对移动。以此方法实现的定位精度在20纳米甚至几个纳米数量级都是可行的。但一旦进入一纳米，甚至亚纳米级定位时，其干涉条纹的漂移和抖动将极大地影响实际定位的确定。
为此，本发明公开了一种能准确对晶圆进行定位，并根据定位结果实现待曝光晶片区域和投影曝光区对准的技术方案。该技术方案可以发现晶片区域的定位误差，而后解决、消除定位误差问题，以实现亚纳米级的对准和套刻。
本发明的实施例给出了一种光学光刻机亚纳米级套刻对准的装置和方法，以及在光刻机系统上的应用场景。本发明把晶圆工作台作为光刻机晶圆上的晶片区域同投影曝光区套刻对准的粗定位。而细致的套刻对准定位是在测量了定位误差以后，实施误差的补偿以后进行。在本发明，这个细微的误差补偿可以用亚纳米级位移驱动装置实现，本发明即是解决驱动物件的亚纳米级位移以及对准方法而达到晶圆上的晶片区域同投影曝光区达到亚纳米级套刻对准精度的巨大改进。所述晶圆包括若干晶片区域120和晶片区域周围的场外区域122，晶圆上设置至少一底层对准标记，所述晶圆表面设置光敏层130，所述底层对准标记在光敏层上形成对应的三维标记，所述三维标记具有与所述光敏层的上表面不在同一水平面的区域。本发明所述的三维标记包括预先设置在晶圆上的底层对准标记在光敏层上形成的三维标记，也包括根据辐照诱导光敏层改性的特点在光敏层上形成的立体图案三维标记。
图1示出本发明一种光刻图形对准装置的示意图，所述对准装置位于一光刻机机体内，所述光刻机机体内包括：一晶圆工作台100，用于承载待处理晶圆110，本发明涉及的光刻机为步进式光刻机，通过逐步移动晶圆工作台实现对晶圆不同晶片区域依次曝光的目的。晶圆工作台上方设置一纳米针尖传感装置90，该纳米针尖传感装置包括至少一个针尖传感头91，所述针尖传感头位于所述光敏层的上方，通过在一定扫描区域内移动扫描并确定该区域内三维标记和/或晶片区域上形成的立体图案三维标记的坐标。
晶圆的上方设置曝光束发生装置300，曝光束发生装置用于提供晶片区域曝光所需的曝光束，所述曝光束在晶圆上形成投影曝光区；除此之外，本发明的对准装置还包括位移驱动装置400，用于根据所述纳米针尖传感装置测得的三维标记坐标调整所述曝光束发生装置和所述晶圆工作台的相对位置，使得所述投影曝光区与待曝光晶片区域对准。
图1所示的光刻图形对准装置还包括一计算机控制系统200，计算机控制系统200用于接收纳米针尖传感装置测得的三维标记坐标并将该三维标记坐标与一基准坐标进行比较，得到两个坐标在横向、纵向或周向上的位移差，两个坐标在周向上的位移差指三维标记在圆周方向的位移差。所述计算机控制系统用于将该位移差传递至所述位移驱动装置400，所述位移驱动装置400使得所述曝光束发生装置和/或所述晶圆工作台进行相应移动以减少同一晶片区域前后两次曝光的误差。
本发明所述的基准坐标为各个三维标记预先存储在计算机控制系统中的在一定扫描区域内的坐标，或者为所述纳米针尖传感装置对所述三维标记在该晶片区域曝光前测得的坐标与为实现下一片需要曝光的晶片区域与投影曝光区对准理论上横向和纵向要移动的距离合并后在所述扫描区域内对应的坐标，理论上横向和纵向要移动的距离预先存储于所述计算机控制系统内，如果所述三维标记为由于辐照诱导光敏层变性(IIRC)而产生的光敏层表面立体图案，所述三维标记的基准坐标为已经曝光的晶片区域的立体图案预先存储在计算机控制系统内在扫描区域内的图形和坐标等参数。
本发明所述的曝光束发生装置发出的曝光束为光束、电子束、离子束或原子束的至少一种，本发明主要以光学光刻机为例进行介绍。
图2示出一种具体实施方式的光刻机结构示意图，具体为一种亚纳米级步进式重复曝光光学光刻机原理图。其光学光刻机系统主要由以下部分组成：
光束发生装置，包括光源10、光闸20、光束整形系统30、光束偏转片或反射镜40、整形透镜组50、掩模板工件台60及投影物镜组70。光刻机计算机控制系统200可以控制光闸20，并决定光源的曝光时间。
晶圆工作台100，用于承载待处理晶圆110，晶圆包括若干晶片区域120，晶圆上设置若干三维标记(后文详细描述)。晶圆工作台100包括移动部分和固定部分，其中移动部分包括晶片区域切换驱动装置105和精密移动装置106，晶片区域切换驱动装置的固定部分104位于晶片区域切换驱动装置105下方，用于承载晶片区域切换驱动装置105并驱动晶圆步进式移动以将不同晶片区域依次暴露于光束发生装置下方。计算机控制系统200与控制晶圆工作台精确移动的晶片区域切换驱动装置105相连，用于驱动晶圆步进式移动以实现所有晶片区域的曝光。晶片区域切换驱动装置具有较大位移范围，晶片区域切换驱动装置为通常微米级别以上的移动距离，目前部分较为精密的晶片区域切换驱动装置的移动可以控制在10纳米以至于到2.5纳米的定位精度。精密移动装置106位于固定装置107的上方，固定装置107置于晶片区域切换驱动装置105的上方，精密移动装置106可以对晶圆在横向、纵向或周向的位置进行亚纳米级别的微调，精密移动装置的设置可以降低晶圆定位对晶圆工作台移动的精确度的依赖，从而允许使用一台移动定位精度较低的晶圆工作台。例如，一台定位精度要求为1纳米的晶圆工作台就可以用一台定位精度1000纳米的晶圆工作台来取代，大大降低了晶圆工作台成本。
纳米针尖传感装置90，包括针尖传感头91和92和连接针尖传感头的微悬臂91a和92a，针尖传感头位于所述晶圆的光敏层上方，用于在一定扫描区域内扫描并确定该区域内三维标图记的坐标，并将获得的信号传输到计算机控制系统200内与基准坐标进行比对。纳米针尖传感装置可以固定在靠近晶圆，但不影响曝光束定位的部件上，本实施例中，针尖传感头91和92固定在投影物镜组70的镜头侧边。针尖传感头随着光子束一起移动，当然针尖传感头也随着光子束一起漂移。这样的好处是针尖传感头的微悬臂可以制作得非常短，从而提高针尖传感头表面三维测量的分辨率。
在图2所示的光刻机结构示意图中，固定在光束投影物镜组70边上的针尖传感头91和92分别置于光束投影物镜组的两边，即每边一个或者一排，形成能够覆盖到晶片区域的投影曝光区两边区域进行测量的情况。即每个或每排针尖传感头对应投影曝光区晶片区域的两边，可以测量晶片区域两边的晶片区域间场外三维标记。每一个或者每一排的针尖传感头都是固定在光束投影物镜组上面，以至于它们相互间的距离是固定的。故相互间的坐标也是固定的。晶片区域两边设置针尖传感头，其好处是大大减小 每个针尖传感头的扫描范围，即只需扫描各自晶片区域中间地带，而无需跨越整个晶片区域从一头的晶片区域间中间地带扫描到晶片区域另一边的晶片区域间中间地带。从而大大提高了针尖传感头扫描的线性度和定位精度。
位移驱动装置400包括驱动晶片区域步进式切换的晶片区域切换驱动装置105和纳米位移驱动装置420。纳米位移驱动装置420与计算机控制系统200相连，根据纳米针尖传感装置90测得的底层对准标记的坐标，控制光束发生装置和/或所述晶圆工作台位置微调，实现待曝光晶片区域与光束发生系统发出的曝光束套刻对准并完成曝光。本实施例中，纳米位移驱动装置420可以选择性的驱动反射镜40、整形透镜组50、掩膜板60、投影物镜组70或晶圆工作台100的至少之一移动，实现投影曝光区和待曝光晶片区域的微调对准。
本实施例中，在掩模板工件台60上安装纳米位移驱动装置61以实现横向移动掩模板，或者在光学投影物镜组70周围安装能推动横向移动透镜镜头的纳米位移驱动装置71，或者横向移动光子束/电子束或者偏转装置40的纳米位移驱动装置41。上述纳米位移驱动装置任意选择之一即可实现对投影曝光区的位置微调，可选地，也可以在上述部件上设置一个以上的纳米位移驱动装置。
为了实现在晶圆上设置三维标记，从而用晶圆上的三维标记来实现晶圆的待曝光晶片区域与投影曝光区的对准，需要在晶圆上设置合适的三维标记。如下将进行详细说明。
图3为预先设置的三维标记在晶圆上的位置示意图。晶圆110包括曝光形成立体图案的晶片区域120和设置在晶片区域外围的场外区域122。三维标记可以设置在晶片区域内，该三维标记称为场内三维标记1201，也可以设置在场外区域内，此三维标记称为场外三维标记1221，场外三维标记可以设置在相邻晶片区域之间的中间地带或设在晶圆边缘区域内。场外三维标记的好处是即使对这些标记进行一些破坏性处理也不会影响晶片区域成品率。这些标记可以被光子束/电子束曝光用作对准坐标标记，可以用光子束/电子束反复“观察”之，即曝光。
场内三维标记1201包括在晶片区域内第一道加工工序前就预先设置的纳米级三维标记，也可以是晶圆上涂有光敏层在光束曝光后在晶片区域表面的光敏层产生的立体图案三维标记。场内三维标记1201可以做到小至几个纳米到几百个纳米，由于其占用的面积很小，因此，即使在晶片区域内制作标记也不会影响到晶片区域成品率问题。
通过对晶圆的一次测量，即可把这些三维标记同各个晶片区域的坐标关系固定下来，以后只要测量这些三维标记即可定位晶片区域的准确坐标位置。假设晶圆在比较长的时间段内通过精确的温度控制没有由于热胀冷缩等原因产生形变，这些坐标间的定位可以容易地精确到单纳米级或亚纳米级。
第一次测量这些三维标记以及晶片区域的位置，即是测定了晶圆相对于晶圆工作台的相对偏差，尤其是晶圆工作台移动时晶圆是否需要转动来调整晶圆工作台同晶圆上晶片区域阵列的平行度。计算机控制系统200通过晶片区域的场外三维标记和场内三维标记控制着光刻机每一个部件并通过预设的控制方法以实现晶片区域的亚纳米级纵向套刻对准并曝光。
三维标记离正要曝光的晶片区域越近，则用于晶片区域的对准精度越高。晶片区域之间的三维标记1221设定在晶片区域之间。这种三维标记的设置适用于步进式重复曝光光刻机。然而对于非掩模板类型的直写的光子束/电子束光刻机，曝光的写场间实际上有很多情况是不允许留出空间的。光栅或者菲涅尔透镜就是例子。
本发明利用能够感知三维纳米级结构的测量技术，如使用针尖传感头传感技术可以实现亚纳米级的三维形貌测量技术(亚纳米级的原子力三维形貌测量技术)，本发明在晶圆上设置三维标记，该三维标记通过针尖传感头传感技术测量实现坐标定位。光敏层和晶圆表面的三维标记可以用来作为对准标记，比如测量三维标记的峰值位置或者凹处位置，就可以确定一个精准的对准坐标。晶圆表面的凹凸结构一般都会引起覆盖其上面的光敏层表面跟随形成凹凸结构，即定位能够垂直穿透，这样覆盖光敏层的表面由于其凹凸结构就可以被测量到。
本发明所述的晶圆包括若干晶片区域，所述晶片区域内部或所述晶片区域周围设置至少一底层对准标记，所述晶圆表面设置光敏层，所述底层对准标记在所述光敏层上形成对应的三维标记，所述三维标记具有与所述光敏层的上表面不在同一水平面的区域。
图4A、图4B和图4C分别示出在晶圆上设置三维标记的具体实施方式。
图4A示出一种凸形三维标记示意图，首先，在晶圆上通过沉积等方法设置一个以上的底层对准标记凸起45a(HAMW)，就是这种预置的纳米级底层对准标记，然后在晶圆上方设置光敏层，由于光敏层具有一定的流动性，且质地较软，该底层对准标记凸起45a(HAMW)会在光敏层上表面形成一对应的凸起结构46a(HAMR)，该凸起结构即为本发明所述的三维标记。若光敏层厚度在10纳米至100纳米之间，在晶圆底层 对准标记45a(HAMW)上面的光敏层表面层也会跟随变成一个三维标记。这个三维标记的高度相应地可以在几个纳米到几十个纳米，通常小于100纳米，准确地给出了其在光敏层表面作为三维标记的位置。这个位置在垂直方向上完全等同于垂直下方的晶圆底层对准标记的位置。以这种方法，我们可以准确地确定晶圆图形的横向坐标，重要的是这个横向坐标可以设置在晶片区域(写场)内。设置了这些三维标记能够决定对准的精确度，以至于对准不依赖于晶圆工作台移动的精确度。从而允许使用一台移动定位精度低的晶圆工作台。例如，一台定位精度要求为1纳米的晶圆工作台就可以用一台定位精度1000纳米的晶圆工作台来取代，大大降低了晶圆工作台成本。
本发明所述的三维标记与光敏层至少有部分区域位于不同的水平面上，例如在本实施例中，该三维标记46a具有凸出于所述光敏层的尖状凸起，当设有该三维标记的晶圆置于本发明的光刻机内时，纳米针尖传感装置的针尖传感头在一定扫描区域内扫描，由于针尖传感头的尖端原子与晶圆表面原子间存在极弱的排斥力，微悬臂将对应于针尖传感头与晶圆表面原子间作用力的等位面而在垂直于晶圆表面方向起伏运动。利用光学检测法或隧道电流检测法可测得微悬臂对应于扫描各点的位置变化，从而获得晶圆表面形貌的信息。本发明中，利用三维标记具有尖状凸起，该尖状凸起到针尖传感头的距离与光敏层上表面到针尖传感头的距离不同，实现针尖传感头扫描时对三维标记的定位。为了准确识别三维标记的坐标，本发明设置的三维标记的高度大于所述光敏层的表面粗糙度，一种可选的高度为小于等于50微米。
图4B示出晶圆表面的三维标记为凹陷部的结构示意图，为实现图4A所示的三维凸起结构需要在晶圆上附加材料。相比之下，晶圆通过刻蚀形成反向的三维“突出”结构45b，即凹陷结构，其优势为无需在晶圆上沉积附加材料，而是“挖”走了现有晶圆的材料，比制造三维凸出结构容易。根据上文描述，光敏层上对应形成凹陷的三维标记46b，由于针尖传感头原子力显微镜能够测量整个三维结构，即使三维结构的坑在其尖尖处有几个纳米大小，但结构所有的三维形貌信息可以将定位提高到单纳米量级水平。
图4C为通过刻蚀技术刻蚀出的晶圆表面的纳米级凹凸型三维标记结构示意图。其优势为无需增加其他材料沉积在晶圆上，也可以获得三维凸出结构作为纳米级三维标记，该实施例中晶圆上的底层对准标记45c包括一个以上的点状结构，对应光敏层上的三维标记46c也具有一个以上的点状结构，使得针尖传感头实现更为精确的定位。
为了实现一个三维标记即可准确定位晶圆坐标，本发明描述的三维标记可选的具有一定的图形特征，所述图形特征除了包括至少一个点状特征44，还包括与所述点状特征相连的棱线特征43，所述点状特征和棱线特征与所述光敏层的上表面不完全位于同一平面内。图4D示出一种立体棱形结构示意图，该棱形结构通过增加若干条与光敏层位于不同水平面内的棱线特征43，增大了三维标记的可探测面积，提高了三维标记的定位准确性。
上述实施例在晶圆表面预置突出或凹陷的纳米三维结构，比如一个微型圆锥体，一个微型金字塔或者一个微型针尖传感头等。其直径尺度在几个纳米至几十个纳米，通常小于100纳米。这些微型结构可以通过等离子体刻蚀技术或者电子束诱导沉积技术(EBID)实现。
本发明在晶圆上可以设置多个三维标记，一种可选方式为，每个晶片区域对应设置至少一个三维标记，该三维标记可以为设置在晶片区域内部的场内三维标记，也可以为设置在晶片区域周围的场外三维标记，该晶片区域周围包括两横向相邻或两纵向相邻的晶片区域之间的场外区域，或者晶圆的边缘与晶片区域对应的场外区域等，可选的，每个晶片区域对应的三维标记坐标与其晶片区域的相对位置固定。上文描述的图4A-4D示出的三维标记为在晶圆上设置绝对位置的三维标记，除此之外，还可以通过光敏层的特性，根据曝光后的特定光敏层形状，利用针尖传感头传感技术对晶圆进行定位。通过相对标记的位置定位提高晶片区域的套刻精度。
上文所述底层对准标记包括在晶圆第一次曝光前即制作到晶圆表面上的标记，也包括在后续曝光工序中设置在所述光敏层下方的标记，考虑到三维标记在图形转移过程中可能发生的损耗导致三维标记的点状特征和棱线特征减弱，当进行一定步骤的工序后，可以重新制作底层对准标记，以提高后续光敏层表面三维标记定位的准确度。
图5A示出一种辐照诱导光敏层改性(IIRC：Irradiation Induced Resist Change)图案示意图，辐照诱导光敏层改性指的是在光子束或者电子束或者其他粒子束辐照曝光的位置，光敏层的化学和/或物理特性产生了变化。化学变化包括光子束/电子束引起光敏层表面化学反应，导致被辐照的光敏层部分从不溶解的状态变化为显影时溶解(正胶)，或者溶解状态通过曝光反应成不能溶解(负胶)。光子束/电子束曝光也会引起的光敏层的物理变化，包括光敏层表面微小的几何尺寸的变化，当光子束/电子束曝光将曝光图形信息转移到光敏层上时，光敏层上的凹凸结构变化也就产生了。比如曝光区域在亚纳米量级或纳米量级上膨胀，相对于未曝光区域48a，形成凸出区域47a， 参见图5A；或者曝光区域萎缩形成凹陷结构，参见附图5B，形成凹陷区域47b和未曝光区域48b，针尖传感头传感技术可以通过测量凸出区域47a和凹陷区域47b实现对某一晶片区域的定位。这种变形可以通过针尖传感头(高度敏感传感头)在亚纳米尺度上探测而感知。
为了保证利用图5A和图5B所示的IIRC标记定位的准确度，可以在晶圆边缘设置若干个三维标记，如设置三个及以上的三维标记，并通过此三维标记确定整个晶圆的位置。然后通过针尖传感头测量和定位晶圆的绝对位置。这里可以使用多个针尖传感头的组合，比如可以用一个线性的多个针尖传感头阵列来传递这些位于晶圆边缘的绝对的三维标记的坐标到晶圆的中间。线性针尖传感头阵列大大扩大了针尖传感头无误差地测量晶圆的范围。一维线性针尖传感头阵列上针尖传感头之间的相互距离是固定的。针尖传感头的移动通过线阵列两端的压电位移或音圈驱动系统将线阵列统一移动。所以针尖传感头之间的相对坐标位置不变。
除了可以利用晶片区域自身曝光产生的立体图案三维标记对后一片晶片区域的曝光进行对准外，还可以在所述曝光束发生装置上设置定位标记发生装置(图中未示出)，所述定位标记发生装置在晶片区域曝光的同时在晶圆区域外围形成一立体定位标记，针尖传感头根据该立体定位标记对待曝光晶片区域的位置进行定位校准。例如，在光学光刻机系统中，可以在掩膜板的正常图形外围设置一个及以上的定位标记发生装置，对一片待曝光晶片区域曝光时，晶片区域边缘同时曝光一立体定位标记，该立体定位标记可选地位于两片晶片区域之间，以减少针尖传感头的扫描区域，提高定位的效率。在进行下一片晶片区域的曝光时，计算机控制系统200根据针尖传感头扫描到的前一片晶片区域对应的立体定位标记的坐标，利用纳米位移驱动装置将待曝光晶片区域和投影曝光区进行对准。
图6示出本发明另一实施例的光刻机结构示意图，在该实施例中，纳米针尖传感装置设置在晶圆工作台100上，晶圆工作台100包括移动部分和固定部分，所述针尖传感头93和94分别通过所述微悬臂93a和94a与所述固定部分相连接。
本实施例的对准方法为首先测得晶片区域间设置的三维标记，和/或者测得晶片区域在曝光前的晶片区域内图形结构和坐标位置。然后曝光，晶片区域切换驱动装置105驱动晶圆工作台110横向移动，腾出投影曝光区给下一个晶片区域用于曝光，同时移动也带来写场移动误差。通过针尖传感头测得晶圆工作台移动后带来的晶片区域外和/或晶片区域内表面上的三维标记新的坐标值，即可同原来三维标记的坐标值作对 比而给出晶片区域移动误差XY坐标(以及XY平面角度)应该的移动量。这个量可以给晶圆工作台作为重新定位，也可以给影响光子束的物件如掩模板或投影物镜组以移动数个纳米。本实施例中，由于针尖传感头传感技术设置在晶圆工作台上，因此可以方便地测量晶圆边缘区域的三维标记，由于晶圆边缘区域的三维标记之间的距离较大，只需要通过数个三维标记即可确定整个晶圆的准确位置。
该方法和装置的问题是晶圆工作台尺寸大，一般要200毫米以上。这样连接针尖传感头同固定针尖传感头基座的微悬臂就会很长。很长的微悬臂可能会降低针尖传感头表面三维测量的分辨率，因此可以对本实施例进行改进。
图7示出本发明另一实施例的光刻机结构示意图，在该实施例中，纳米针尖传感装置结合了图2和图6中固定位置的特点。一组针尖传感头93和94固定在晶圆工作台上，另一组针尖传感头91和92则固定在光子束一边，如投影物镜组两侧。这样的好处是能够准确测量待曝光晶片区域对应的场外三维标记的坐标，同时能只需要通过数个三维标记即可确定整个晶圆的准确位置。
图8示出本发明一种实施例的多个针尖传感头及晶片区域对应关系的示意图，通过多个针尖传感头测量和确定每个晶片区域的坐标位置。该实施例中，所述多个针尖传感头91，92，……9n通过连接件140固定连接，并根据所述晶片区域的分布横向设为一排，形成一横向针尖传感头阵列。根据前文描述，在准备步骤中，待处理晶圆上设置至少一底层对准标记，且所述底层对准标记在所述光敏层上对应形成三维标记；对晶圆进行曝光时，将准备步骤中设有三维标记的晶圆置于上文所述的光刻机内，所述光刻机内靠近晶圆设置一投影物镜组70，所述投影物镜组在晶圆上对应一投影曝光区，驱动所述晶圆工作台的晶片区域切换驱动装置105将待曝光的第一晶片区域置于所述投影物镜组下方；利用针尖传感头91-9n中的至少一个在一定扫描区域内对光敏层进行扫描，获得第一三维标记的位置坐标，例如为三维标记1221，将所述第一三维标记的位置坐标与该第一三维标记的基准坐标比较，获得两个位置坐标的差值；所述位移驱动装置根据两个位置坐标的差值调整所述曝光束发生装置和所述晶圆工作台的相对位置，使得所述投影曝光区与所述第一晶片区域对准，所述光束发生装置发出曝光光束到所述晶圆的第一晶片区域，实现所述第一晶片区域的曝光。该第一三维标记的基准坐标预先存储于所述计算机控制系统，当所述三维标记位于基准坐标处时，所述第一晶片区域与投影曝光区对准。
完成第一晶片区域的曝光后，将所述第二晶片区域置于所述投影物镜组的下方，此时，可以有多种对准标记实现对所述第一晶片区域与投影曝光区的对准。一种方式为：所述针尖传感头扫描所述第一三维标记移动后的位置坐标并与该第一三维标记移动后的基准坐标进行比较得到两个位置坐标的偏差，所述第一三维标记移动后的基准坐标为第一晶片区域曝光时所述第一三维标记的位置坐标与为实现下一片需要曝光的晶片区域与投影曝光区对准，晶圆理论上横向和纵向要移动的距离合并后在所述扫描区域内对应的坐标。晶圆理论上横向和纵向要移动的距离根据曝光产生的晶片区域的大小以及相邻两晶片区域之间的距离等参数预先确定并存储于计算机系统内。在前一步晶片区域曝光时实现准确定位的一三维标记移动一步或几步后的定位可以根据移动的晶片区域的数量准确确定其基准坐标。利用该同一三维标记进行对准时，需要考虑针尖传感头的数量和扫描区域的范围，由于需要对同一三维标记进行跟踪扫描，可选的设置两个针尖传感头分别在两侧对晶片区域曝光前的三维标记和晶圆移动后的同一三维标记进行坐标测量，另一种可选方式为，选择一个扫描范围较大的针尖传感头，实现对同一三维标记的跟踪扫描。
另一种对准方式为：完成第一晶片区域的曝光后，将所述第二晶片区域置于所述投影物镜组的下方，所述针尖传感头扫描第二三维标记位置坐标并与该第二三维标记的基准坐标进行比较得到两个位置坐标的偏差，所述位移驱动装置根据所述位置坐标的差值调整所述曝光束发生装置和所述晶圆工作台的相对位置，使得所述投影曝光区与所述第二晶片区域对准，并实现所述第二晶片区域的曝光，所述第二个三维标记的基准坐标预先存储于所述计算机控制系统内。为了保准对准的精确度，可选的，所述第一三维标记靠近所述第一晶片区域设置，所述第二三维标记靠近所述第二晶片区域设置。
第三种对准方式为：完成第一晶片区域的曝光后，将所述第二晶片区域置于所述投影物镜组的下方，所述针尖传感头扫描所述第一晶片区域曝光后光敏层上形成的立体图案的图形和坐标并与该立体图案预先存储在计算机控制系统内的基准图形和坐标进行比较得到两个立体图案位置的差值，所述位移驱动装置根据所述位置坐标的差值调整所述曝光束发生装置和所述晶圆工作台的相对位置，使得所述投影曝光区与所述第二晶片区域对准，并实现所述第二晶片区域的曝光。
上述三种对准方式可以根据晶片区域附近是否设置底层对准标记产生的三维标记进行选择一种，也可以选择两种或两种以上的对准方式，以提高对准精度。在对某一 晶片区域进行对准时，可以同时扫描一个以上的三维标记坐标并与其所对应的基准坐标进行差值比对，以提高对准的精度。
第三晶片区域及后续晶片区域依次暴露于投影物镜组下方，根据上文所述的对准方法实现曝光。
可选的，所述纳米针尖传感装置固定在所述投影物镜组的一侧或两侧，并与所述投影物镜组之间的位置相对固定。利用该同一三维标记进行对准时，需要考虑针尖传感头的数量和扫描区域的范围，由于需要对同一三维标记进行跟踪扫描，可选的设置两个针尖传感头分别在两侧对晶片区域曝光前的三维标记和晶圆移动后的同一三维标记进行坐标测量，另一种可选方式为，选择一个扫描范围较大的针尖传感头，实现对同一三维标记的跟踪扫描。当设置两个或两个以上的针尖传感头时，相邻两针尖传感头之间的距离等于一个晶片区域的横向宽度与两个晶片区域之间的场外区域宽度之和，可选的，相邻两针尖传感头之间的距离为上述两个距离之和的倍数。如此设计可以保证晶片区域依次曝光时，针尖传感头可以在较小的范围内扫描以实现对三维标记的精确定位。多个针尖传感头彼此之间位置通过连接件相对固定，以实现晶圆上某一三维标记坐标定位向横向针尖传感头阵列上其他晶片区域位置的传递。此时任何一个针尖传感头测得的晶圆坐标的精确定位都可以传输到其他针尖传感头测量的坐标定位，传输时没有误差。
针尖传感头之间的间距可以大于或者等于晶片区域加晶片区域间距离的尺寸，以至于一个针尖传感头测量晶圆边缘或者靠近晶圆边缘的三维标记坐标位置，另一个针尖传感头测量晶片区域间中间地带的三维标记，以及再一个针尖传感头测量另一个晶片区域的晶片区域间中间地带，并依此类推。
具体地，第一个针尖传感头测量晶圆边缘的三维标记的位置，横向针尖传感头阵列把这个位置绝对值传递到第二个针尖传感头，起到了第二个针尖传感头的位置无需在晶圆上设置三维标记也能确定绝对坐标的作用。第一个针尖传感头的坐标还可以通过第N个针尖传感头传递坐标到晶圆的更里面，一直传递到最后一个针尖传感头。而最后一个针尖传感头一般可以传递测量到晶圆另一端边缘上的三维标记。针尖传感头无法移动到的晶片区域可以通过横向写场拼接的方法传递数个晶片区域的曝光坐标定位，由于传递数量有限而避免过高的定位坐标误差积累，从而形成晶圆上所有晶片区域都能套刻定位精确地对准曝光的场景。
利用针尖传感头阵列实现晶圆边缘上的纳米级三维标记，或者晶圆中间的纳米级三维标记坐标同光束相对位置的定位，为保证晶圆相对于光束的定位，需使用至少三个三维标记。三个三维标记在晶圆上的分布越开，越能准确地定位晶圆。图9为多针尖传感头L型针尖传感头阵列。该阵列能够用相距非常大的晶圆边缘的三维标记作为晶圆的准确坐标来定位。
图9示出本发明一种实施例的多个针尖传感头及晶片区域对应关系的示意图，本实施例中，多个针尖传感头通过连接件150连接为L型阵列排布，在图8所示实施例的公开的横向针尖传感头阵列基础上增加了能够测量边缘区域其他排三维标记的至少一个针尖传感头101，该L形阵列能够用相距非常大的晶圆边缘的三维标记作为晶圆的准确坐标来定位。
针尖传感头阵列实现晶圆边缘两端的纳米级三维标记同光束相对位置的定位是最准确的定位方法之一。图10示出本发明一种实施例的多个针尖传感头及晶片区域对应关系的示意图，本实施例中，多个针尖传感头通过连接件160连接为U型阵列，在图8所示实施例的公开的横向针尖传感头阵列基础上两端分别增加了能够测量边缘区域其他排三维标记的至少一个针尖传感头111。由此可以通过设置在晶圆两端边缘的各三个以上距离拉开的纳米级三维标记来确定晶圆相对于曝光光束的准确坐标位置。该阵列能够用相距非常大的晶圆两端的三维标记作为晶圆的准确坐标来定位。U型的两臂可以不一样长。其针尖传感头线性阵列可以固定在光束投影物镜组上，也可以固定在晶圆工作台上。
所述针尖传感头可以在大气或真空环境下测量晶圆表面结构，也可以在浸液环境下将针尖传感头浸入液体中测量晶圆表面结构。对于浸液式光刻，针尖传感头测量的所述三维标记可以为浸液环境中的三维标记，也可以为晶片区域同曝光束之外没有浸液环境中相邻晶片区域对应的三维标记作为三维标记。
所述针尖传感头探测的三维标记的表面结构数据是所述三维标记表面结构同所述针尖传感头的针尖结构的数学卷积，因此针尖传感头的形状可能会对其探测的三维标记的表面结构数据造成影响，因此所述针尖传感头在对三维标记进行测量前需要对所述针尖结构进行测量和校准，以提高测量的准确性。
前文描述的情况主要包括对晶圆在横向、纵向或周向进行位置调节以实现与投影曝光区的对准，在某些情况下，晶圆可能与曝光束垂直度发生偏差，例如原本应该水平设置的晶圆发生一定角度的倾斜，为了检测此种情况，可以设置三个或三个以上的 针尖传感头，且设置三个或者三个以上的针尖传感头位于不同的直线上，当三个或三个以上的针尖传感头分别测量各自扫描区域内的三维标记时，可以根据识别到的三维标记的高度差判断该三维标记所在的晶圆区域是否发生倾斜，导致其与针尖传感头之间的距离发生了变化。并根据测得的高度差并通过计算机控制系统驱动所述晶圆工作台调节至所述晶圆同曝光束垂直。
利用本发明所述对准装置实现的亚纳米级高精度光刻晶片区域套刻对准方法，包含有以下前期准备步骤：
准备步骤1：光束定位准备。将针尖传感头固定在曝光束发生装置的投影物镜组侧边位置，因此针尖传感头同曝光束的相对位置是固定的。如此，针尖传感头的坐标系即是曝光束投影曝光区经过固定平移的坐标系。首先对涂有光敏层的晶圆(可以是一片带有测试结构的晶圆)对准。使用结构足够精细的掩模板作为校准掩模板。让光束通过掩模板曝光，掩模板图形即转移到晶圆表面的光敏层上并在光敏层形成晶片区域图形区，由于辐照诱导光敏层变性(IIRC)而产生光敏层表面立体图案。这个立体图案即是光束在晶圆表面的投影坐标位置。用针尖传感头测量晶片区域外的三维标记和晶片区域内的IIRC立体图案三维标记即确定了光束投影曝光区位置同针尖传感头的坐标相对固定的坐标位置。
针尖传感头同投影物镜组(即光束投影图形)的坐标一起连动。当使用针尖传感头测量晶片区域的定位时，就如同曝光束的眼睛，去寻找晶片区域的确切位置。
准备步骤2：晶圆准备，在晶圆涂布光敏层前或者后，用针尖传感头测量各个晶片区域的三维标记坐标位置，以确定各个场外三维标记坐标的相互位置。
准备步骤3：找出第一次晶圆上各个晶片区域曝光的投影曝光区坐标位置。
方法一：在晶圆没有经过光刻曝光之前，晶圆上没有任何图形，所以不存在本次投影曝光区同上一次已经曝光在晶圆上留下图形的对准问题。可以简单地按照光束投影曝光形成第一个晶片区域图形区，然后晶圆工作台移动到下一个晶片区域曝光图形，直至晶圆上所有图形都完成曝光。通过针尖传感头测量每个晶片区域的场外三维标记坐标以及测量晶片区域投影曝光区光敏层变化(IIRC)获得的场内立体图案三维标记坐标，即可把晶片区域场外三维标记坐标同晶片区域投影曝光区的位置坐标联系起来。以后只要测量晶片区域场外三维标记坐标即可确定投影曝光区应该的位置。
方法二：在晶圆第一次曝光后，将在光敏层上的曝光图形转移到晶圆上后，比如通过等离子刻蚀方法实现，直接测量和记录晶片区域场外三维标记的坐标同晶片区域 立体图案三维标记坐标位置，以至于将来只要测定晶片区域场外三维标记坐标即可推算出晶片区域投影曝光区位置。测量可以通过针尖传感头，或者通过光刻机以外的其他测量仪器。
准备步骤1，准备步骤2和准备步骤3是一次性的。在开始时测量晶圆一次以后，即可使用场外三维标记来确定晶片区域的坐标位置了。
晶片区域坐标参照点。通过上述准备步骤，晶片区域坐标建立了同每个晶片区域的场外三维标记坐标的关联。确定场外三维标记坐标，即可确定晶片区域位置坐标。
准备步骤4：如果测得的晶圆上的各个晶片区域排列阵列同承载晶圆的晶圆工作台有角度上的偏差，则需要校准该晶圆同晶圆工作台水平两维移动方向即周向上的角度误差。在完成上述准备步骤后，开始进入晶片区域套刻对准步骤：
对准步骤1：第一晶片区域套刻对准工序开始。将涂有光敏层120的晶圆110放在晶圆工作台100上，通过固定在光束投影物镜组70上的针尖传感头测量晶片区域场外三维标记，利用准备步骤3获得的场外三维标记坐标同晶片区域图形区固定的坐标关系，即可确定光束是否正对晶片区域图形区的位置。由此可以获得光束投影曝光区同晶片区域图形区位置的坐标偏差，即(ΔX1，ΔY1)。
对准步骤2：利用与掩膜板固定的纳米位移驱动装置61，把对准步骤1获得的坐标(ΔX1，ΔY1)给掩膜板作误差量相应的相向补偿移动。以使得投影曝光区同晶片区域的图形区位置对准。
对准步骤3：对处于投影曝光区内的第一晶片区域实施曝光。
对准步骤4：启用针尖传感头测量已经曝光的晶片区域场外三维标记坐标和场内IIRC立体图案三维标记的位置；这等于重新测量了晶片区域坐标位置和光束投影曝光区位置，即时校准了晶片区域位置和光束投影曝光区位置。这样即使光刻机中部分部件随着时间有微小的漂移，通过本步骤可以加以矫正。
对准步骤5：进行第二晶片区域的曝光前准备。移动晶圆工作台100带动晶圆110横向移动，从而使刚被曝光的第一晶片区域区移出投影曝光区成为带有立体图案的晶片区域，为随后晶圆的第二晶片区域进入投影曝光区腾出空间。晶圆工作台的移动会带来晶片区域定位误差；
对准步骤6：启动针尖传感头测量和识别出第二晶片区域对应的场外三维标记坐标，与上述移出投影曝光区的第一晶片区域相关的场外三维标记坐标和/或场内IIRC的立体图案三维标记坐标进行比较，得出第二晶片区域需要移动的偏差(ΔX2，ΔY2)；
对准步骤7：利用与掩膜板固定的纳米位移驱动装置61，根据对准步骤6获得的坐标(ΔX2，ΔY2)驱动掩膜板作误差量相应的相向补偿移动。以至于光束投影曝光区同晶片区域的光敏层下面的图形区位置对准。
对准步骤8：对处于投影曝光区内的第二晶片区域实施曝光。
对准步骤9：启用针尖传感头测量已经曝光的晶片区域场外三维标记坐标或/和场内IIRC立体图案三维标记的位置；
对准步骤10：进行第三晶片区域的曝光前准备。晶圆工作台100带动晶圆110横向移动，从而使刚被曝光的第二晶片区域区移出投影曝光区成为带有立体图案的晶片区域，为随后晶圆的第三晶片区域进入投影曝光区而腾出空间；晶圆工作台的移动会带来晶片区域定位误差。
对准步骤11：启动针尖传感头测量和识别出第三晶片区域相关联的场外三维标记坐标和测量上述移出投影曝光区的第二晶片区域场内IIRC的立体图案三维标记，与上述移出投影曝光区的第一晶片区域相关的场外三维标记坐标和/或场内IIRC的立体图案三维标记坐标进行比较，得出第二晶片区域需要移动的偏差(ΔX3，ΔY3)；
对准步骤12：利用与掩膜板固定的纳米位移驱动装置61，根据对准步骤11获得的坐标(ΔX3，ΔY3)驱动掩膜板作误差量相应的相向补偿移动。以至于光束投影曝光区同晶片区域的图形位置对准。
对准步骤13：周而复始，完成整个晶圆全部晶片区域的曝光、移动和套刻动作。
本实施例描述的用于对准的三维标记不仅可以选用正要等待曝光的晶片区域与邻近的晶片区域间中间地带的场外三维标记，而且也可以选用前一个曝光晶片区域表面(已涂有光敏层)的IIRC立体图案三维标记作为下一个晶片区域曝光的坐标参照系。由于使用IIRC无需晶片区域间设置三维标记，可以大大减少晶片区域间三维标记的设置。然而以IIRC立体图案三维标记作为上一个已曝光晶片区域的坐标系会导致针尖传感头测量每个曝光晶片区域带来的误差的积累。所以一般情况下将设有对应三维标记的晶片区域和未设置对应场外三维标记的晶片区域间隔设置，通过使用数个IIRC图形作为投影曝光区对准定位的参照点，省掉数个晶片区域间的场外三维标记，同时保证积累的总误差在可以允许的范围内。
本发明图8-图10示出的实施例中，具有多个针尖传感头的线性阵列同晶片区域场外三维标记连同晶片区域场内IIRC三维标记结合，可以更加少量的设置场外三维标记的数量。具体地，横向针尖传感头阵列直接将第一个针尖传感头同固定在针尖传感头 线性阵列上的其他针尖传感头的移动误差绑定到第一个针尖传感头的位置，跨越了中间多个晶片区域由于没有使用邻近的晶片区域间中间地带的三维标记来确认晶片区域定位可能带来的误差积累。
在另外的实施例中可以仅在晶圆的边缘设置纳米级三维标记，然后用多个针尖传感头线性阵列将在晶圆里面的坐标位置通过线性传感头阵列直接连接到晶圆边缘认定的晶片区域三维标记坐标位置上，消除了中间多个晶片区域前后曝光，参照前一个晶片区域曝光带来的误差积累。
通过上文的描述，本发明为了提高晶圆在步进式曝光时的套刻精度，主要是通过以下技术方案实现的：
亚纳米精度测量晶片区域/写场实际坐标位置的技术。
采用针尖传感头传感技术，其中包括针尖传感头原子力显微技术。原子力显微技术是针尖传感头传感技术中的一种。能够测量晶圆亚纳米级精度的表面三维形貌，以及表面功函数纳米级分布等。
物件的亚纳米级位移驱动技术。
第一种技术是移动亚纳米级步长的压电陶瓷技术。利用压电原理可以产生亚纳米级的移动。但是一般的压电移动都是非线性的，而且有磁滞回线。
第二种技术是电磁驱动技术。音圈电机(Voice Coil Motor)是一种特殊形式的直接驱动电机。具有结构简单体积小、高速、高加速、响应快等特性。其定位精度能达到1/30纳米量级。其工作原理是，通电线圈(导体)放在磁场内就会产生力，力的大小与施加在线圈上的电流成比例。基于此原理制造的音圈电机运动形式可以为直线或者圆弧。这两种技术都可以用在本发明中。
物件的亚纳米位移驱动加定位技术。
有了上面的测量和驱动技术就可以实现亚纳米级定位。这个定位就是要使晶圆的晶片区域/写场相对于光子束/电子束作纳米级的定位位移调整，以消除晶圆工作台移动或光子束/电子束移动带来的相对坐标偏移。由此即可提供多种相对于光子束/电子束位置有偏差的晶圆晶片区域/写场位置误差的纠正方法和装置，以实现亚纳米级的晶片区域/写场的横向拼接和纵向套刻对准。对物件的位移驱动和定位的实施举例：
在光子束/电子束光刻机中，可以使用亚纳米级定位的晶圆工作台，或者在现有晶圆工作台上再设置一个更精确的皮米级的小型晶圆工作台用来做精确定位，即比现有的晶圆工作台的移动步长更小。(小型晶圆工作台移动速度可以慢一些)。
在使用掩模板的光子束/电子束光刻机中，可以设置驱动掩模板工件台纳米级移动的驱动装置，可以设置驱动光子束/电子束投影物镜组的纳米级移动，就足以实现晶片区域/写场的对准误差的矫正。
在光子束/电子束直写的光刻机中，可以设置驱动光子束/电子束投影物镜组位移，让镜头移动数个以及数十个纳米，就足以实现其相对于写场/晶片区域的对准定位误差的矫正。
在光子束/电子束直写的或用掩模板的光刻机中，可以设置驱动光子束/电子束本身或者偏转装置实现光子束和电子束的位移和坐标矫正。
提供一种光刻机中闭环控制式的测量和晶片区域的对准然后曝光的装置和方法。
本发明公开的光刻机对准系统拥有晶片区域套刻对准的测量-移动-再测量的闭环控制特点，其超高精度光刻系统晶片区域具体套刻对准的方法为：
方法一：通过场外三维标记1221作为晶片区域对准定位的参照点，如晶片区域间或者晶圆边缘的三维突出(凹入)标记的坐标位置，即用针尖传感头测出晶片区域图形的位置(晶圆上各个晶片区域图形同晶圆上三维突出(凹入)标记的坐标位置及其相对坐标位置是事先确定的，不受晶圆工作台移动和光束偏移而变化)。然后通过晶圆工作台100移动将已曝光的晶片区域移出投影曝光区，继续测量晶片区域中间或晶圆边缘的三维突出(凹入)标记的新坐标，并与先前在投影曝光区前一个已经曝光的晶片区域的坐标比较形成的坐标差，得出下一个要曝光的晶片区域的坐标偏移差值。用这个坐标差可以驱动曝光束发生装置例如掩模板进行纳米级水平移动进行补偿，还可以设置驱动光子束/电子束投影物镜组的纳米级水平移动，还可以设置驱动光子束/电子束本身或者偏转镜的纳米级水平移动，还可以设置驱动晶圆工作台或者安装在晶圆工作台上步长更小的压电晶圆工作台，就足以实现晶片区域/写场的对准误差的矫正。
方法二：通过首个晶片区域曝光以后的辐照诱导光敏层改性(IIRC)形成的立体图案，如图5A和5B作为下一个晶片区域对准的位置坐标。在此方法中，待曝光的晶片区域可以不设置对应的三维标记，即晶片区域内或者晶片区域周围不设置三维标记，针尖传感头在一定扫描区域内扫描时，根据前一片已经完成曝光的晶片区域上形成的 立体图案三维标记，确定晶片区域的边界，进而确定下一片待曝光晶片区域是否需要进行纳米级位移微调以及调整的偏差。
方法三：本方法结合上述方法一和方法二进行设定。考虑到方法一最佳实施方式是在每个晶片区域都对应设置三维标记，由于一个晶圆上有众多晶片区域，因此就需要相当多的底层对准标记事先制作在晶圆上。而方法二中采用上一片晶片区域的曝光立体图案三维标记进行定位可能存在积累误差的问题，所以本方法对方法一和方法二进行组合，将设置对应的三维标记的晶片区域和未设置三维标记的晶片区域间隔设置，即用晶片区域对应的三维标记作为绝对参照点，实现第一个晶片区域的曝光套刻对准，然后用晶片区域曝光的辐照诱导光敏层改性(IIRC)作为横向晶片区域的对准坐标，将对准传递到下一个晶片区域的对准和曝光，在传递数个晶片区域的曝光以后，再获得晶片区域对应的三维标记作为绝对套刻对准标记，重新开始下一批晶片区域的绝对曝光对准。这样就在保证了所有晶片区域套刻精度的同时，大大减少了晶圆上底层对准标记的设置量。
本发明适用于深紫外和极紫外光学光刻机，解决了曝光前不能用光子束直接面对涂有光敏层的晶圆进行对准测量，只能通过晶圆工作台的移动来定位晶片区域的技术难题。本发明公开的技术方案不会产生积累性误差。因此避免了晶圆工作台每次都要返回原点并以原点为绝对参照点再移动到指定位置，这会大大提高了工作速度。此外，本发明还解决了即使晶圆工作台定位准确，由于光子束的投影物镜组以及掩模板的漂移(通过热胀冷缩等各种因素)，光子束会产生漂移而导致其最终光子束同晶圆的对准复杂化的技术问题。
以上做法都是基于晶圆与曝光束之间相对位置的闭环控制原理来进行晶片区域套刻对准。这个对准机制精度高于一个精确的晶圆工作台。因为即使晶圆工作台暂时定位精确，光束在晶圆上的漂移是晶圆工作台难以补偿的，也是在晶圆和光束间对准的激光干涉仪难以补偿的。
尽管本发明的内容已经通过上述优选实施例作了详细介绍，但应当认识到上述的描述不应被认为是对本发明的限制。在本领域技术人员阅读了上述内容后，对于本发明的多种修改和替代都将是显而易见的。因此，本发明的保护范围应由所附的权利要求来限定。

Claims (55)

  1. 一种光刻图形对准装置，所述装置位于一光刻机机体内，其特征在于，所述装置包括：
    一晶圆工作台，用于承载待处理晶圆，所述晶圆包括若干晶片区域和晶片区域外围的场外区域，所述晶圆表面设置光敏层，所述光敏层设有三维标记，所述三维标记具有与所述光敏层的上表面不在同一水平面的区域；
    纳米针尖传感装置，包括一针尖传感头，所述针尖传感头位于所述光敏层的上方，用于在一扫描区域内移动扫描并确定该扫描区域内三维标记的坐标；
    曝光束发生装置，用于提供晶片区域曝光所需的曝光束，并在所述光敏层上形成投影曝光区；
    位移驱动装置，用于根据所述针尖传感头测得的三维标记坐标调整所述曝光束发生装置和所述晶圆工作台的相对位置，使得所述投影曝光区与待曝光晶片区域对准。
  2. 如权利要求1所述的光刻图形对准装置，其特征在于：所述装置还包括一计算机控制系统，所述计算机控制系统用于接收纳米针尖传感装置测得的三维标记坐标并与该三维标记的基准坐标进行比较，得到两个坐标的差值，所述计算机控制系统用于将该差值传递至所述位移驱动装置，并控制所述曝光束发生装置和/或所述晶圆工作台相互移动以补偿所述差值。
  3. 如权利要求2所述的光刻图形对准装置，其特征在于：所述基准坐标为所述三维标记预设的位置坐标，当所述三维标记位于该预设位置时，待曝光晶片区域与所述投影曝光区对准，所述基准坐标预先存储于所述计算机控制系统内。
  4. 如权利要求2所述的光刻图形对准装置，其特征在于：所述基准坐标为所述纳米针尖传感装置对所述三维标记在该晶片区域曝光前测得的坐标与为实现下一片需要曝光的晶片区域与投影曝光区对准理论上晶圆要移动的距离合并后在所述扫描区域内对应的坐标，理论上晶圆在横向和纵向要移动的距离预先存储于所述计算机控制系统内。
  5. 如权利要求1所述的光刻图形对准装置，其特征在于：所述光敏层上的三维标记包括设置在光敏层下方的底层对准标记在光敏层上对应形成的三维标记和/或由曝光束在光敏层表面曝光后形成的辐照诱导光敏层改性(IIRC)形成的三维立体图案。
  6. 如权利要求5所述的光刻图形对准装置，其特征在于：所述底层对准标记在光敏层上对应形成的三维标记位于所述晶片区域内或者相邻晶片区域之间的场外区域内。
  7. 如权利要求5或6任一项所述的光刻图形对准装置，其特征在于：所述底层对准标记包括在晶圆第一次曝光前制作到晶圆衬底表面上的标记和/或在后续曝光工序中设置在所述光敏层下方的标记。
  8. 如权利要求1所述的光刻图形对准装置，其特征在于：所述三维标记的高度大于所述光敏层的表面粗糙度。
  9. 如权利要求1所述的光刻图形对准装置，其特征在于：所述三维标记的坐标包括晶圆的横向位置坐标、纵向位置坐标以及周向位置坐标。
  10. 如权利要求1所述的光刻图形对准装置，其特征在于：所述光敏层上设置两个或两个以上三维标记。
  11. 如权利要求1所述的光刻图形对准装置，其特征在于：所述三维标记具有一定的图形特征，所述图形特征包括至少一个点状特征，所述点状特征与所述光敏层的上表面位于不同的水平面内。
  12. 如权利要求11所述的光刻图形对准装置，其特征在于：所述图形特征还包括与所述点状特征相连的棱线特征，所述棱线特征与所述光敏层的上表面不完全位于同一平面内。
  13. 如权利要求1所述的光刻图形对准装置，其特征在于：所述三维标记为凸出于或凹陷于所述光敏层上表面的立体结构。
  14. 如权利要求13所述的光刻图形对准装置，其特征在于：所述立体结构为锥形结构、多边棱形结构、金字塔形结构中的至少一种。
  15. 如权利要求1所述的光刻图形对准装置，其特征在于：每个晶片区域对应设置至少一个三维标记，所述三维标记位于所述晶片区域内或该晶片区域周围的场外区域内，所述三维标记的基准坐标预先存储于计算机控制系统内。
  16. 如权利要求1所述的光刻图形对准装置，其特征在于：部分晶片区域未设置对应的三维标记，该晶片区域根据针尖传感头测得的前一个完成曝光的晶片区域内的立体图案三维标记实现与所述投影曝光区对准。
  17. 如权利要求16所述的光刻图形对准装置，其特征在于：未设置对应三维标记的晶片区域与设置有对应三维标记的晶片区域间隔设置。
  18. 如权利要求1所述的光刻图形对准装置，其特征在于：所述曝光束发生装置上设置定位标记发生装置，所述定位标记发生装置在晶片区域曝光的同时在晶圆区域外围形成一立体定位标记，针尖传感头根据该立体定位标记对待曝光晶片区域的位置进行定位校准。
  19. 如权利要求1所述的光刻图形对准装置，其特征在于：所述三维标记的高度小于等于50微米。
  20. 如权利要求1所述的光刻图形对准装置，其特征在于：所述针尖传感头为主动式原子力针尖传感头、激光反射式原子力针尖传感头、隧道电子探针传感头或纳米级表面功函数测量传感头中的一种或多种的组合。
  21. 如权利要求1所述的光刻图形对准装置，其特征在于：所述针尖传感头在大气或真空环境下测量晶圆表面结构，或在浸液环境下将针尖传感头浸入液体中测量晶圆表面结构。
  22. 如权利要求21所述的光刻图形对准装置，其特征在于：对于浸液式光刻，所述三维标记为浸液环境中的三维标记，或者晶片区域同曝光束之外没有浸液环境中相邻晶片区域对应的三维标记。
  23. 如权利要求1所述的光刻图形对准装置，其特征在于：所述针尖传感头所测的三维标记的表面结构数据是所述三维标记表面结构同所述针尖传感头的针尖结构的数学卷积，所述针尖传感头在对三维标记进行测量前进行所述针尖结构的测量和校准。
  24. 如权利要求1所述的光刻图形对准装置，其特征在于：所述纳米针尖传感装置还包括微悬臂，所述微悬臂一端固定，一端设置所述针尖传感头。
  25. 如权利要求24所述的光刻图形对准装置，其特征在于：所述纳米针尖传感装置包括一个或一个以上的针尖传感头，所述针尖传感头通过所述微悬臂固定在所述曝光束发生装置的一侧或两侧。
  26. 如权利要求25所述的光刻图形对准装置，其特征在于：所述曝光束发生装置包括设置在所述晶圆上方的投影物镜组，所述一个或一个以上的针尖传感头通过微悬臂固定在所述投影物镜组的一侧或两侧两侧。
  27. 如权利要求24所述的光刻图形对准装置，其特征在于：所述晶圆工作台包括移动部分和固定部分，所述针尖传感头通过所述微悬臂与所述固定部分相连接。
  28. 如权利要求27所述的光刻图形对准装置，其特征在于：所述纳米针尖传感装置包括两个或两个以上的针尖传感头，其中一个或一个以上的所述针尖传感头固定在所 述晶圆工作台的固定部分上，一个或一个以上的所述针尖传感头固定在所述曝光束发生装置的侧边，若干所述针尖传感头之间的相对距离固定。
  29. 如权利要求1所述的光刻图形对准装置，其特征在于：所述纳米针尖传感装置包括两个或两个以上的针尖传感头，若干所述针尖传感头通过一连接件固定在所述曝光束发生装置的一侧或两侧，若干所述针尖传感头之间的距离相对固定。
  30. 如权利要求1所述的光刻图形对准装置，其特征在于：所述纳米针尖传感装置包括三个或者三个以上的针尖传感头，所述针尖传感头通过连接件固定在晶圆工作台的固定部分上和/或通过连接件固定在曝光束发生装置上，所述针尖传感头位于不同直线上，以确定晶圆同曝光束之间是否垂直。
  31. 如权利要求30所述的光刻图形对准装置，其特征在于：每个所述针尖传感头测试其位置对应的晶圆表面或者光敏层表面到曝光束发生装置的距离，根据测得的距离相同与否判断晶圆与曝光束是否垂直，并通过计算机控制系统驱动所述晶圆工作台调节至所述晶圆同曝光束垂直。
  32. 如权利要求26-29任一项所述的光刻图形对准装置，其特征在于：所述纳米针尖传感装置包括多个通过连接件固定的针尖传感头，所述多个针尖传感头根据所述晶片区域的分布横向设为一排，形成一横向针尖传感头阵列。
  33. 如权利要求32所述的光刻图形对准装置，其特征在于：所述横向针尖传感头阵列一端设置纵向分布的至少一针尖传感头，形成一L形针尖传感头阵列。
  34. 如权利要求32所述的光刻图形对准装置，其特征在于：所述横向针尖传感头阵列两端分别设置纵向分布的针尖传感头，形成一U形针尖传感头阵列。
  35. 如权利要求32所述的光刻图形对准装置，其特征在于：所述相邻两针尖传感头之间的距离大于等于一个晶片区域的横向宽度。
  36. 如权利要求1所述的光刻图形对准装置，其特征在于：所述位移驱动装置包括晶片区域切换驱动装置和纳米位移驱动装置。
  37. 如权利要求36所述的光刻图形对准装置，其特征在于：所述晶片区域切换驱动装置与所述晶圆工作台的移动部分相连，用于带动待曝光晶片区域依次暴露于所述投影曝光区下方。
  38. 如权利要求37所述的光刻图形对准装置，其特征在于：所述晶圆工作台的移动部分还包括精密移动装置，所述纳米位移驱动装置为所述精密移动装置。
  39. 如权利要求36所述的光刻图形对准装置，其特征在于：所述纳米位移驱动装置与所述曝光束发生装置和/或所述晶圆工作台的精密移动装置相连，用于控制所述曝光束发生装置和/或所述晶圆工作台在横向和/或纵向和/或周向移动。
  40. 如权利要求36所述的光刻图形对准装置，其特征在于：所述纳米位移驱动装置驱动所述曝光束发生装置和/或所述精密移动装置移动的工作原理为压电原理、音圈驱动原理或者电磁驱动原理中的至少一种。
  41. 如权利要求1所述的光刻图形对准装置，其特征在于：所述曝光束发生装置发出的曝光束为光束、电子束、离子束或原子束的至少一种。
  42. 如权利要求36所述的光刻图形对准装置，其特征在于：所述曝光束发生装置为光束发生装置，所述光束发生装置包括光源、光闸、光束偏转片/反射镜，掩模板和投影物镜组，所述纳米位移驱动装置与所述光束偏转片/反射镜，所述掩模板和所述投影物镜组的至少之一相连，以调整所述光束发生装置的投影曝光区位置。
  43. 如权利要求42所述的光刻图形对准装置，其特征在于：所述至少一针尖传感头固定在所述投影物镜组的至少一侧。
  44. 如权利要求41所述的光刻图形对准装置，其特征在于：所述曝光束为平行光束或者高斯型光束。
  45. 如权利要求42所述的光刻图形对准装置，其特征在于：所述光束的整形、聚焦系统可以由光学透镜组成，也可以由光学反射镜组成。
  46. 如权利要求1所述的光刻图形对准装置，其特征在于：所述晶圆包括完整晶圆、部分晶圆，或者需要光刻曝光处理的非晶圆物质。
  47. 一种步进式光刻机，用于对晶圆内多个晶片区域实现重复曝光，其特征在于：所述光刻机内设置如权利要求1-46任一项所述的光刻图形对准装置。
  48. 一种步进式光刻机的工作方法，其特征在于，所述方法包括：
    准备步骤，在晶圆上设置至少一底层对准标记，并在所述待处理晶圆上涂覆光敏层，所述底层对准标记在所述光敏层上对应形成三维标记；
    对准步骤，将准备步骤中设有三维标记的晶圆置于权利要求47所述的光刻机内，所述光刻机内靠近晶圆设置一投影物镜组，所述投影物镜组在晶圆上对应一投影曝光区，驱动所述晶圆工作台将待曝光的第一晶片区域置于所述投影物镜组下方；利用所述针尖传感头在一定扫描区域内对光敏层进行扫描，获得第一三维标记的位置坐标，将所述第一三维标记的位置坐标与该第一三维标记的基准坐标比较，获得两个位置坐 标的差值；所述位移驱动装置根据两个位置坐标的差值调整所述曝光束发生装置和所述晶圆工作台的相对位置，使得所述投影曝光区与所述第一晶片区域对准；
    曝光步骤，所述光束发生装置发出曝光束到所述晶圆的第一晶片区域，实现所述第一晶片区域的曝光。
  49. 如权利要求48所述的方法，其特征在于：完成第一晶片区域的曝光后，将所述第二晶片区域置于所述投影物镜组的下方，所述针尖传感头扫描所述第一三维标记移动后的位置坐标并与该第一三维标记移动后的基准坐标进行比较得到两个位置坐标的偏差，所述位移驱动装置根据所述位置坐标的差值调整所述曝光束发生装置和所述晶圆工作台的相对位置，使得所述投影曝光区与所述第二晶片区域对准，并实现所述第二晶片区域的曝光。
  50. 如权利要求49所述的方法，其特征在于：所述第一三维标记移动后的基准坐标为第一晶片区域曝光时所述第一三维标记的位置坐标与为实现下一片需要曝光的晶片区域与投影曝光区对准，晶圆理论上横向和纵向要移动的距离合并后在所述扫描区域内对应的坐标。
  51. 如权利要求49或50任一项所述的方法，其特征在于：所述投影物镜组两侧分别设置至少一所述针尖传感头，或者所述投影物镜组一侧设置一针尖传感头，且所述针尖传感头的扫描宽度大于一待曝光晶片区域的宽度。
  52. 如权利要求48所述的方法，其特征在于：完成第一晶片区域的曝光后，将所述第二晶片区域置于所述投影物镜组的下方，所述针尖传感头扫描第二三维标记位置坐标并与该第二三维标记的基准坐标进行比较得到两个位置坐标的偏差，所述位移驱动装置根据所述位置坐标的差值调整所述曝光束发生装置和所述晶圆工作台的相对位置，使得所述投影曝光区与所述第二晶片区域对准，并实现所述第二晶片区域的曝光，所述第二个三维标记的基准坐标预先存储于所述计算机控制系统内。
  53. 如权利要求52所述的方法，其特征在于：所述第一三维标记靠近所述第一晶片区域设置，和/或所述第二三维标记靠近所述第二晶片区域设置。
  54. 如权利要求48所述的方法，其特征在于：完成第一晶片区域的曝光后，将所述第二晶片区域置于所述投影物镜组的下方，所述针尖传感头扫描所述第一晶片区域曝光后光敏层上形成的立体图案的图形和坐标并与该立体图案预设的图形和坐标进行比较得到两个立体图案位置的差值，所述位移驱动装置根据所述位置坐标的差值调整所 述曝光束发生装置和所述晶圆工作台的相对位置，使得所述投影曝光区与所述第二晶片区域对准，并实现所述第二晶片区域的曝光。
  55. 如权利要求48-54任一项所述的方法，其特征在于：所述纳米针尖传感装置固定在所述投影物镜组的一侧或两侧，并与所述投影物镜组之间的位置相对固定。
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CN111983899A (zh) * 2020-06-11 2020-11-24 百及纳米科技(上海)有限公司 亚纳米级高精度光刻写场拼接方法、所用光刻机系统、晶圆及电子束漂移的测定方法
CN112445088A (zh) * 2020-12-04 2021-03-05 百及纳米科技(上海)有限公司 一种步进式光刻机、其工作方法及图形对准装置
CN214474416U (zh) * 2020-12-04 2021-10-22 百及纳米科技(上海)有限公司 一种步进式光刻机及图形对准装置

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