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 PDFInfo
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- 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
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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.
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Abstract
Description
Claims (55)
- 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***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。
- 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***,所述计算机控制***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***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。
- 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***内。
- 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***内。
- 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。
- 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。
- 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。
- 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。
- 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。
- 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。
- 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。
- 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。
- 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。
- 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。
- 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***内。
- 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。
- 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。
- 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***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。
- 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。
- 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。
- 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。
- 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。
- 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。
- 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。
- 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。
- 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。
- 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。
- 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。
- 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。
- 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。
- 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***驱动所述晶圆工作台调节至所述晶圆同曝光束垂直。
- 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。
- 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。
- 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。
- 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。
- 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。
- 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。
- 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。
- 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。
- 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。
- 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。
- 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。
- 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。
- 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。
- 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***可以由光学透镜组成,也可以由光学反射镜组成。
- 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。
- 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。
- 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。
- 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。
- 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。
- 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。
- 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***内。
- 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。
- 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。
- 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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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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CN101329514A (zh) * | 2008-07-29 | 2008-12-24 | 上海微电子装备有限公司 | 一种用于光刻设备的对准***及对准方法 |
JP2015046427A (ja) * | 2013-08-27 | 2015-03-12 | トヨタ自動車株式会社 | アライメント方法及びパターニング用マスク |
CN106547171A (zh) * | 2015-09-17 | 2017-03-29 | 上海微电子装备有限公司 | 一种用于光刻装置的套刻补偿***及方法 |
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***、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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