CN214474416U

CN214474416U - Stepping photoetching machine and graph alignment device

Info

Publication number: CN214474416U
Application number: CN202022897890.4U
Authority: CN
Inventors: 周向前; 尹志尧; 朗格诺; 杜川
Original assignee: Baiji Nanotechnology Shanghai Co Ltd
Current assignee: Baiji Nanotechnology Shanghai Co Ltd
Priority date: 2020-12-04
Filing date: 2020-12-04
Publication date: 2021-10-22
Anticipated expiration: 2030-12-04

Abstract

The utility model discloses a marching type lithography machine and figure aligning device. The utility model discloses set up a plurality of three-dimensional marks on the wafer to this coordinate as wafer surface location is predetermine, utilizes needle point sensing head sensing technology to measure the coordinate that this three-dimensional mark obtained the sub-nanometer precision of wafer surface, then removes the wafer workstation, follows with and surveys the new coordinate of the three-dimensional mark after the wafer workstation removes and reachs the chip region position coordinate error value with the same three-dimensional nanometer coordinate comparison before the wafer workstation removes. The coordinate error is compensated by moving the exposure beam generating device relative to the wafer region using closed loop control principles to achieve re-precise alignment of the relative coordinate positions. The utility model discloses can use the deep ultraviolet and extreme ultraviolet optical lithography machine that use mask slice, also can use the sub-nanometer level wafer region of electron beam/photon beam direct-write lithography machine or write the field and transversely and vertically aim at application scenes such as concatenation.

Description

Stepping photoetching machine and graph alignment device

Technical Field

The utility model relates to a photoetching technology field especially relates to alignment and positioning technology field of photoetching pattern.

Background

The development of microelectronics and optoelectronics has led to the rapid development of integrated circuit chips, integrated optical chips. These industries form the basis of core devices and chips for modern computers, display screens and even the entire information industry. Currently, the technology nodes of the modern chip industry have reached 5 nanometers or even less.

The micro-nano device such as a chip can be manufactured without the photoetching technology. The lithography techniques include general optical lithography, deep ultraviolet/extreme ultraviolet lithography, electron beam lithography, ion beam lithography, and the like. By means of these key photolithography techniques, fine photolithography patterns and even microscopic and microscopic device structures, such as integrated circuit chips and optoelectronic integrated chips, can be manufactured.

Existing optical lithography systems, including deep ultraviolet optical lithography machines and extreme ultraviolet optical lithography machines, have been widely used in the fields of industrial chip manufacturing and MEMS manufacturing. As wafers get larger and larger, 12 inch diameter wafers are now popular and are moving toward larger size wafers. Any system cannot expose the entire wafer at once. It is common practice to sequentially expose a DIE area (DIE) on the wafer. After one chip area is exposed, the wafer moves to the next adjacent chip area through the movement of the wafer worktable and is aligned by alignment, and then exposure is carried out. Here, alignment means that the pattern of the exposure must be vertically aligned (i.e. overlay alignment) with the existing pattern on the wafer region before the photolithography exposure can be performed. The alignment accuracy, i.e., the overlay accuracy, cannot be at least several times smaller than the smallest dimension of the circuit pattern on the wafer area. This size is currently around 5-10 nm. A multi-beam electron beam lithography machine used for manufacturing a mask plate, such as MBMW-101 series of the austria high-tech company IMS, can be used for manufacturing a 5 nm node mask plate, and the alignment accuracy of the alignment is below 5 nm. The lithography machine series TWINSCAN3400B and 4300C of the Dutch extreme ultraviolet optical lithography machine ASML company are used for 5 nanometer technical nodes, and the alignment precision is 2.5 nanometers and 1.5 nanometers respectively. The chip structure size is then on the order of 3 nm. The alignment accuracy of the lithography machine's overlay alignment positioning facing the wafer area exposure must be required to be at or below 1 nm. In the face of such high requirements of the alignment precision of the wafer region, there is no related positioning technology at present, so that new technology must be put into practical use.

The requirement for the extremely high positioning accuracy of the wafer worktable is difficult to realize and also comes from a characteristic of a photoetching process, and is a great disadvantage that a layer of photosensitive layer is coated on the wafer before exposure. In the photolithography technique, a photolithography pattern is transferred to a photosensitive layer by exposure, and then the photolithography pattern on the photosensitive layer is transferred to a wafer by an etching process. It should be noted that the photosensitive layer on the wafer is used to cover the upper surface of the wafer, which is "light-sensitive" so that the electron beam or photon beam cannot be irradiated (i.e., exposed) before exposure to make surface observation, and further cannot penetrate the photosensitive layer to obtain the pattern of the wafer under the photosensitive layer. Therefore, the pattern to be exposed can not form alignment with the pattern of the wafer area under the photosensitive layer, namely, the photoetching machine can only be operated by the blind person, the wafer worktable is moved, and then the light beam is exposed by the blind person. The positioning of the wafer exposure is inaccurate, and the overlay error is large.

SUMMERY OF THE UTILITY MODEL

In order to solve the above technical problem, the utility model provides a photoetching pattern alignment device, the device is located a photoetching machine body, include:

the wafer comprises a plurality of chip areas and an off-site area on the periphery of the chip areas, a photosensitive layer is arranged on the surface of the wafer, a three-dimensional mark is arranged on the photosensitive layer, and the three-dimensional mark is provided with an area which is not on the same horizontal plane with the upper surface of the photosensitive layer;

the nanometer needle point sensing device comprises a needle point sensing head, wherein the needle point sensing head is positioned above the photosensitive layer and used for moving scanning in a scanning area and determining the coordinate of a three-dimensional mark in the scanning area;

an exposure beam generating device for providing an exposure beam required by the exposure of the wafer area and forming a projection exposure area on the photosensitive layer;

and the displacement driving device is used for adjusting the relative positions of the exposure beam generating device and the wafer workbench according to the three-dimensional mark coordinates measured by the needle point sensing head so as to align the projection exposure area with the wafer area to be exposed.

Optionally, the apparatus further includes a computer control system, the computer control system is configured to receive the three-dimensional mark coordinate measured by the nano-needle tip sensing device and compare the three-dimensional mark coordinate with the reference coordinate of the three-dimensional mark to obtain a difference between the two coordinates, and the computer control system is configured to transmit the difference 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.

Optionally, the reference coordinate is a preset position coordinate of the three-dimensional mark, when the three-dimensional mark is located at the preset position, the wafer region to be exposed is aligned with the projection exposure region, and the reference coordinate is stored in the computer control system in advance.

Optionally, the reference coordinate is a coordinate corresponding to the scanning region after combining a coordinate measured by the nano needle tip sensing device before the exposure of the three-dimensional mark in the wafer region with a distance that theoretically should be moved for aligning the next wafer region to be exposed with the projection exposure region, and the distance that theoretically should be moved for the wafer in the transverse direction and the longitudinal direction is pre-stored in the computer control system.

Optionally, the three-dimensional mark on the photosensitive layer includes a three-dimensional mark formed on the photosensitive layer by a bottom layer alignment mark disposed below the photosensitive layer and/or a three-dimensional stereo pattern formed by irradiation induced photosensitive layer modification (IIRC) formed by exposure of an exposure beam on the surface of the photosensitive layer.

Optionally, the three-dimensional mark correspondingly formed on the photosensitive layer by the bottom layer alignment mark is located in the wafer region or in an off-field region between adjacent wafer regions.

Optionally, the bottom layer alignment mark includes a mark fabricated on the surface of the wafer substrate before the first exposure of the wafer and/or a mark disposed below the photosensitive layer in a subsequent exposure process.

Optionally, the height of the three-dimensional mark is greater than the surface roughness of the photosensitive layer.

Optionally, 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, i.e., the angular coordinates of the figure of the three-dimensional mark in the circumferential direction.

Optionally, two or more three-dimensional marks are disposed on the photosensitive layer.

Optionally, the three-dimensional mark has a certain pattern feature, and the pattern feature includes at least one dot feature, and the dot feature is located in a different horizontal plane from the upper surface of the photosensitive layer.

Optionally, the pattern features further include ridge features connected to the dot features, and the ridge features and the upper surface of the photosensitive layer are not completely in the same plane.

Optionally, the three-dimensional mark is a three-dimensional structure protruding from or recessed into the upper surface of the photosensitive layer.

Optionally, the three-dimensional structure is at least one of a conical structure, a polygonal prismatic structure and a pyramidal structure.

Optionally, each wafer region corresponds to at least one three-dimensional mark, the three-dimensional mark is located in the wafer region or in an off-site region around the wafer region, and the reference coordinates of the three-dimensional mark are stored in the computer control system in advance.

Optionally, a part of the wafer region is not provided with a corresponding three-dimensional mark, and the wafer region is aligned with the projection exposure region according to the three-dimensional mark of the three-dimensional pattern in the previous wafer region which is subjected to exposure and measured by the needle tip sensing head.

Optionally, the wafer region without the corresponding three-dimensional mark and the wafer region with the corresponding three-dimensional mark are arranged at intervals.

Optionally, the exposure beam generating device is provided with a positioning mark generating device, the positioning mark generating device forms a three-dimensional positioning mark on the periphery of the wafer region while exposing the wafer region, and the needle tip sensing head performs positioning calibration on the position of the wafer region to be exposed according to the three-dimensional positioning mark.

Optionally, the height of the three-dimensional mark is less than or equal to 50 micrometers.

Optionally, the tip sensing head is one or a combination of an active atomic force tip sensing head, a laser reflection atomic force tip sensing head, a tunnel electronic probe sensing head, or a nanometer surface work function measurement sensing head.

Optionally, the probe tip sensing head measures the wafer surface structure in an atmospheric or vacuum environment, or the probe tip sensing head is immersed in liquid in an immersion environment to measure the wafer surface structure.

Optionally, for immersion lithography, the three-dimensional marks are three-dimensional marks in an immersion environment, or three-dimensional marks corresponding to regions of the wafer outside of the exposure beam that do not have an immersion environment adjacent to the wafer.

Optionally, the surface structure data of the three-dimensional mark measured by the needle tip sensing head is a mathematical convolution of the surface structure of the three-dimensional mark and the needle tip structure of the needle tip sensing head, and the needle tip sensing head performs measurement and calibration of the needle tip structure before measuring the three-dimensional mark.

Optionally, the nano needle tip sensing device further comprises a micro cantilever, one end of the micro cantilever is fixed, and the needle tip sensing head is arranged at one end of the micro cantilever.

Optionally, the nano-tip sensing device includes one or more tip sensing heads, and the tip sensing heads are fixed on one side or two sides of the exposure beam generation device through the micro-cantilever.

Optionally, the exposure beam generating device includes a projection objective lens set disposed above the wafer, and the one or more needle tip sensing heads are fixed to one side or both sides of the projection objective lens set through micro-cantilevers.

Optionally, the wafer stage includes a moving portion and a fixing portion, and the needle tip sensing head is connected to the fixing portion through the micro-cantilever.

Optionally, the nano-tip sensing device includes two or more tip sensing heads, wherein one or more tip sensing heads are fixed on a fixed portion of the wafer stage, and one or more tip sensing heads are fixed on a side of the exposure beam generator.

Optionally, the nano needle tip sensing device includes two or more needle tip sensing heads, the plurality of needle tip sensing heads are fixed on one side or two sides of the exposure beam generating device through a connecting member, and the relative distance between the plurality of needle tip sensing heads is fixed.

Optionally, the nano-tip sensing device includes three or more tip sensing heads, the tip sensing heads are fixed on the fixed portion of the wafer stage through a connector and/or are fixed on the exposure beam generator through a connector, and the tip sensing heads are located on different straight lines to determine whether the wafer and the exposure beam are perpendicular to each other.

Optionally, each of the needle tip sensing heads tests a distance from the surface of the wafer or the surface of the photosensitive layer corresponding to the position of the needle tip sensing head to the exposure beam generating device, determines whether the wafer and the exposure beam are perpendicular according to the same measured distance, and drives the wafer worktable to adjust the wafer to be perpendicular to the exposure beam through the computer control system.

Optionally, the nano needle tip sensing device includes a plurality of needle tip sensing heads fixed by connectors, and the plurality of needle tip sensing heads are arranged in a row according to the distribution of the wafer region, so as to form a transverse needle tip sensing head array.

Optionally, one end of the transverse needle tip sensing head array is provided with at least one needle tip sensing head which is longitudinally distributed, so as to form an L-shaped needle tip sensing head array.

Optionally, longitudinally distributed needle tip sensing heads are respectively arranged at two ends of the transverse needle tip sensing head array to form a U-shaped needle tip sensing head array.

Optionally, the distance between two adjacent tip sensing heads is greater than or equal to the lateral width of one wafer region.

Optionally, the displacement driving device includes a wafer area switching driving device and a nano displacement driving device.

Optionally, the wafer area switching driving device is connected to the moving part of the wafer stage, and is configured to drive the wafer areas to be exposed to be sequentially exposed below the projection exposure area.

Optionally, the moving part of the wafer stage further includes a precision moving device, and the nano-displacement driving device is the precision moving device.

Optionally, the nano-displacement driving device is connected to the exposure beam generating device and/or the precision moving device of the wafer stage, and is configured to control the exposure beam generating device and/or the wafer stage to move in the transverse direction and/or the longitudinal direction and/or the circumferential direction.

Optionally, the working principle of the nano displacement driving device driving the exposure beam generating device and/or the precision moving device to move is at least one of a piezoelectric principle, a voice coil driving principle or an electromagnetic driving principle.

Optionally, the exposure beam generated by the exposure beam generating device is at least one of a light beam, an electron beam, an ion beam or an atomic beam.

Optionally, the exposure beam generating device is a light beam generating device, the light beam generating device includes a light source, an optical shutter, a light beam deflecting plate/reflecting mirror, a mask plate and a projection objective lens group, the nanometer displacement driving device is connected to the light beam deflecting plate/reflecting mirror, and at least one of the mask plate and the projection objective lens group is connected to adjust a position of a projection exposure area of the light beam generating device.

Optionally, the at least one needle tip sensing head is fixed to at least one side of the projection objective lens group.

Optionally, the light beam is a parallel light beam or a gaussian light beam.

Optionally, the beam shaping and focusing system may be composed of an optical lens or an optical mirror.

Optionally, the wafer includes a complete wafer, a partial wafer, or a non-wafer substance requiring a photolithography exposure process.

Further, the utility model also discloses a marching type lithography machine for realize the repeated exposure to a plurality of wafer regions in the wafer, set up like above the photoetching figure aligning device in the lithography machine.

Further, the utility model also discloses a working method of marching type lithography machine, the method includes:

the method comprises the steps of preparing, namely arranging at least one bottom layer alignment mark on a wafer, and coating a photosensitive layer on the wafer to be processed, wherein the bottom layer alignment mark correspondingly forms a three-dimensional mark on the photosensitive layer;

an alignment step, namely placing the wafer provided with the three-dimensional mark in the preparation step into the photoetching machine, wherein a projection objective lens group is arranged in the photoetching machine close to the wafer, corresponds to a projection exposure area on the wafer, and drives the wafer workbench to place a first chip area to be exposed below the projection objective lens group; scanning the photosensitive layer in a certain scanning area by using the needle point sensing head to obtain a position coordinate of a first three-dimensional mark, and comparing the position coordinate of the first three-dimensional mark with a reference coordinate of the first three-dimensional mark to obtain a difference value of the two position coordinates; the displacement driving device adjusts the relative positions of the exposure beam generating device and the wafer workbench according to the difference value of the two position coordinates, so that the projection exposure area is aligned with the first wafer area;

and in the exposure step, the light beam generating device sends out an exposure beam to a first chip area of the wafer to realize the exposure of the first chip area.

Optionally, after the exposure of the first wafer region is completed, the second wafer region is placed below the projection objective lens group, the needle tip sensing head scans the position coordinate of the first three-dimensional mark after movement and compares the position coordinate with the reference coordinate of the first three-dimensional mark after movement to obtain a deviation of the two position coordinates, and the displacement driving device adjusts the relative positions of the exposure beam generating device and the wafer worktable according to the difference of the position coordinates, so that the projection exposure region is aligned with the second wafer region, and the exposure of the second wafer region is realized.

Optionally, the reference coordinate of the first three-dimensional mark after moving is a corresponding coordinate in the scanning area after the distance of the wafer which is moved in the horizontal and vertical directions in theory is combined, in order to align the position coordinate of the first three-dimensional mark when the first wafer area is exposed with the next wafer area to be exposed and the projection exposure area.

Optionally, at least one needle tip sensing head is respectively arranged on two sides of the projection objective group, or one needle tip sensing head is arranged on one side of the projection objective group, and the scanning width of the needle tip sensing head is greater than the width of a wafer area to be exposed.

Optionally, after the exposure of the first wafer region is completed, the second wafer region is placed below the projection objective lens group, the needle tip sensing head scans a position coordinate of the second three-dimensional mark and compares the position coordinate with a reference coordinate of the second three-dimensional mark to obtain a deviation of the two position coordinates, the displacement driving device adjusts the relative positions of the exposure beam generating device and the wafer worktable according to the difference of the position coordinates, so that the projection exposure region is aligned with the second wafer region, the exposure of the second wafer region is realized, and the reference coordinate of the second three-dimensional mark is stored in the computer control system in advance.

Optionally, the first three-dimensional mark is disposed near the first wafer region, and/or the second three-dimensional mark is disposed near the second wafer region.

Optionally, after the exposure of the first wafer region is completed, the second wafer region is placed below the projection objective lens group, the needle tip sensing head scans a graph and a coordinate of a three-dimensional pattern formed on the exposed photosensitive layer of the first wafer region and compares the graph and the coordinate with a preset graph and coordinate of the three-dimensional pattern to obtain a difference between positions of the two three-dimensional patterns, and the displacement driving device adjusts relative positions of the exposure beam generating device and the wafer stage according to the difference between the positions of the two three-dimensional patterns, so that the projection exposure region is aligned with the second wafer region, and the exposure of the second wafer region is realized.

Optionally, the nano needle tip sensing device is fixed on one side or two sides of the projection objective lens group, and is relatively fixed with the projection objective lens group.

The photolithography technique that the photoetching pattern aligning device of the utility model can aim at is a deep ultraviolet and extreme ultraviolet photoetching machine, for example, an ultraviolet stepping repeated exposure photoetching machine (Stepper). The method is characterized in that light beams form an exposure pattern through a mask plate and irradiate the exposure pattern onto a wafer coated with a photosensitive layer. And aligning and exposing one chip area each time, aligning and exposing another chip area through the movement of the wafer worktable, and finally completely exposing the chip area on the wafer. Of course, the present invention is also applicable to the lithography machine with direct writing of electron beam/photon beam.

The utility model discloses set up three-dimensional mark on the wafer surface, through a measurement to the wafer, can fix these three-dimensional marks with each regional coordinate relation of wafer to as long as measure these three-dimensional marks can fix a position the regional accurate coordinate position of wafer in the future. If the wafer is not deformed due to thermal expansion and contraction through precise temperature control in a long period of time, the positioning between the coordinates can be easily accurate to a single nanometer level.

The first measurement of the three-dimensional marks and the positions of the chip areas is to determine the relative deviation of the wafer with respect to the wafer stage, especially whether the wafer needs to be rotated to adjust the parallelism of the wafer stage movement and the array of chip areas on the wafer while the wafer stage is moving.

Unlike electron beams that can be used to observe and measure the pattern on the wafer surface by scanning electron microscopy, photon beam lithography machines (deep ultraviolet lithography machines and extreme ultraviolet lithography machines) cannot participate in alignment positioning with single nanometer and sub-nanometer dimensional accuracy because the photon wavelength used for exposure does not allow the measurement of the wafer pattern to achieve nanometer resolution. And utilize the technical scheme of the utility model can make the positioning accuracy of photon beam lithography machine to nanometer and sub-nanometer level.

The closer the three-dimensional mark is to the wafer area being exposed, the higher the alignment accuracy for the wafer area. Three-dimensional marks are set between wafer areas or within wafer areas, which is the type of stepper that is used for step-and-repeat exposure lithography machines. If the three-dimensional mark disposed inside the wafer region can be as small as several nanometers to several hundred nanometers, it will be very practical because the occupied area is very small, and the yield problem of the wafer region will not be affected even if the three-dimensional mark is made in the wafer region.

The utility model discloses a can perceive three-dimensional nanometer level structure's measurement technique, for example use needle point sensing head sensing technique to realize sub-nanometer's three-dimensional appearance measurement technique (sub-nanometer's atomic force three-dimensional appearance measurement technique), then nanometer's three-dimensional mark can be measured through needle point sensing head sensing technique and play nanometer coordinate effect. 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 the valley position of the three-dimensional marks, a precise alignment coordinate can be determined. The concave-convex structure on the surface of the wafer generally causes the surface of the photosensitive layer covering the wafer to follow and form the concave-convex structure, namely, the positioning can vertically penetrate through the concave-convex structure, so that the surface of the photosensitive layer can be measured due to the concave-convex structure and the position of the surface. The utility model discloses a needle point sensing head sensing technology can make optical measurement reach sub-nanometer's measurement.

The utility model discloses except that can adopting the three-dimensional mark of above-mentioned description to fix a position the wafer, can also carry out the location that the wafer region was exposed according to the modified characteristics of the photosensitive layer of Irradiation induction, the photosensitive layer of Irradiation induction modification (IIRC: Irradiation Induced Resist Change) indicates in the position that photon beam or electron beam or other particle beam Irradiation exposed, and the chemistry and/or the physical property of photosensitive layer have produced the Change. The chemical change includes a chemical reaction of the surface of the photosensitive layer by the photon beam/electron beam, resulting in a change of the irradiated photosensitive layer portion from an insoluble state to a soluble state upon development (positive glue), or a soluble state to an insoluble state by exposure (negative glue). The physical changes of the photosensitive layer, including the changes of the surface of the photosensitive layer with small geometric dimensions, such as expansion or shrinkage on the sub-nanometer level or nanometer level, can also be caused by photon beam/electron beam exposure to form a concave-convex structure. When the photon beam/electron beam exposure transfers the exposure pattern information to the photosensitive layer, the relief structure change on the photosensitive layer is generated. This deformation can be sensed by probing the tip sensor head (highly sensitive sensor head) at a sub-nanometer scale.

The utility model has the advantages that:

1. a brand-new technology capable of measuring the actual position of the wafer area graph with sub-nanometer precision is provided for the photoetching machine;

2. methods and apparatus are provided for correcting for nanometer-scale movement between an exposure photon beam/electron beam coordinate position relative to a wafer area/write field coordinate position;

3. providing an (extreme) ultraviolet optical lithography machine with ultra-high overlay alignment precision in a wafer area;

4. methods and apparatus are provided for combined lateral and longitudinal alignment stitch error correction and then exposure of wafer regions/write fields in a lithography machine under closed-loop control principles.

Drawings

In order to more clearly illustrate the technical solution of the present invention, the drawings required for the description of the technical solution of the present invention are briefly introduced below, and obviously, the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, the idea of the present invention shown in these drawings to obtain other embodiments all belong to the protection scope of the present invention without creative work.

FIG. 1 is a schematic view of an alignment apparatus for lithography patterns according to the present invention.

FIG. 2 is a schematic diagram of a lithography machine according to an embodiment.

Fig. 3 shows a schematic diagram of the position of the three-dimensional mark on the wafer.

FIG. 4A is a schematic view of a three-dimensional mark protruding from a surface; FIG. 4B is a schematic diagram of a three-dimensional mark with a concave surface; fig. 4C is a schematic view of a three-dimensional mark with a concave-convex surface, and fig. 4D is a schematic view of a three-dimensional structure of the three-dimensional mark.

FIG. 5A is a schematic view of a radiation-induced expansion of a photosensitive layer; fig. 5B is a schematic view of a shrinkage structure of the radiation-induced photosensitive layer.

FIG. 6 is a schematic structural diagram of a lithography machine according to another embodiment of the present invention.

FIG. 7 is a schematic structural diagram of a lithography machine according to another embodiment of the present invention.

Fig. 8 is a schematic diagram illustrating a plurality of tip sensing heads and wafer area mapping according to an embodiment of the invention.

Fig. 9 is a schematic diagram of a tip sensor head and wafer area mapping according to another embodiment of the present invention.

Fig. 10 is a schematic diagram of a tip sensor head and wafer area mapping according to another embodiment of the present invention.

The specific implementation mode is as follows:

the concept and technical solution of the present invention will be described in detail with reference to the accompanying drawings.

In the field of stepping repeated exposure lithography machines, after exposure of one wafer area is finished, a wafer is moved to the next wafer area for alignment by the movement of a wafer worktable, and then exposure is carried out. At present, the alignment of a wafer region on a wafer and a light beam projection exposure region is mainly realized by the accurate positioning of a wafer worktable. This alignment can introduce positioning errors caused by movement of the wafer stage. And alignment errors due to beam offset cannot be corrected in time. The whole positioning process belongs to an open-loop control state that no coordinate measurement exists before positioning and no coordinate measurement exists after positioning. There is no real-time measurement of alignment errors and feedback information using alignment errors. This error is typically in the order of a few nanometers to tens of nanometers.

The precision of the laser wafer stage can be achieved with a precision of a few nanometers by high-order processing of the wavelength of the laser interference. The driving device of the wafer stage can be in a piezoelectric driving mode or even a voice coil driving mode. The moving and positioning precision can reach sub-nanometer level or even pico-meter level. The problem is that the position measured by laser interferometry is the distance of the optical path and not necessarily the distance that the actual wafer stage actually needs to move. As long as there is little temperature change around the wafer stage or the light beam, the change of air concentration and air pressure will cause the optical path difference and the actual distance to be inconsistent, so that the distance measured by the laser is not the actual distance that the wafer stage needs to move. And the error of each movement can be accumulated by the multiple movements of the laser wafer workbench, so that the error is amplified. The utility model discloses people's research discovers: to measure single nanometer and sub-nanometer accuracy, it is very difficult to use even the most accurate laser interference correction mechanism, and even if the correction is successful, it is occasional.

In addition, it has been discovered that some deep ultraviolet and extreme ultraviolet optical lithography machines have a laser interference positioning mechanism between the wafer and the exposure beam, i.e., the parts of the lithography machine that are connected to the wafer to generate the exposure beam are formed and positioned relative to each other by laser interference. This is a closed loop control system. On the wafer area, a grating structure is provided in an intermediate zone of the wafer area. Laser light is emitted from the lithography machine components associated with the exposure beam to the grating structure in the intermediate zone between the wafer regions and then returned to the lithography machine components associated with the exposure beam to interfere with the emitted laser light or to interfere with the grating structure on one side of the exposure beam to form a double grating. The movement of the interference fringes corresponds to the relative movement between the wafer region and the exposure beam. Positioning accuracy on the order of 20 nm or even a few nm is feasible with this approach. But once a nanometer, even sub-nanometer, positioning is entered, the drift and jitter of its interference fringes will greatly affect the determination of the actual positioning.

Therefore, the utility model discloses an ability accuracy is fixed a position the wafer to realize treating the technical scheme that exposes the alignment of wafer region and projection exposure area according to the location result. The technical scheme can find the positioning error of the wafer region, and then solve and eliminate the problem of the positioning error so as to realize sub-nanometer alignment and overlay.

The embodiment of the utility model provides a device and method that optical lithography machine sub-nanometer level alignment was aimed at to and the application scene on the lithography machine system. The utility model discloses regard wafer workstation as the coarse positioning that the alignment was carved with projection exposure area to the wafer region on the photoetching machine wafer. And the fine overlay alignment positioning is carried out after the positioning error is measured and the error compensation is carried out. The utility model discloses, this slight error compensation can be realized with sub-nanometer displacement drive arrangement, the utility model discloses solve sub-nanometer displacement and the alignment method of drive article and reach the wafer region on the wafer and reach the huge improvement of sub-nanometer alignment precision with the projection exposure area promptly. The wafer comprises a plurality of chip areas 120 and off-field areas 122 around the chip areas, at least one bottom layer alignment mark is arranged on the wafer, a photosensitive layer 130 is arranged on the surface of the wafer, the bottom layer alignment mark forms a corresponding three-dimensional mark on the photosensitive layer, and the three-dimensional mark has an area which is not in the same horizontal plane with the upper surface of the photosensitive layer. The three-dimensional mark includes the three-dimensional mark that sets up the bottom alignment mark on the wafer in advance and form on photosensitive layer, also includes the three-dimensional mark of the stereogram that forms on photosensitive layer according to the characteristics that the photosensitive layer of irradiation induction modified.

Fig. 1 shows a schematic diagram of a lithographic pattern alignment apparatus according to the present invention, the alignment apparatus is located in a lithographic apparatus body, the lithographic apparatus body includes: a wafer workstation 100 for bear pending wafer 110, the utility model relates to a lithography machine is marching type lithography machine, realizes the purpose of exposing in proper order to the different wafer regions of wafer through progressively removing the wafer workstation. A nano needle point sensing device 90 is arranged above the wafer workbench, and comprises at least one needle point sensing head 91 which is positioned above the photosensitive layer, and the coordinates of a three-dimensional mark in a certain scanning area and/or a three-dimensional pattern mark formed on a wafer area are determined by moving and scanning in the area.

An exposure beam generating device 300 is arranged above the wafer and used for providing an exposure beam required by the exposure of the chip area, and the exposure beam forms a projection exposure area on the wafer; in addition, the utility model discloses an aligning device still includes displacement drive arrangement 400 for according to the three-dimensional mark coordinate adjustment that nanometer needle point sensing device surveyed exposure beam generating device with the relative position of wafer workstation makes projection exposure area aligns with waiting to expose the wafer region.

The apparatus for aligning a lithography pattern shown in fig. 1 further includes a computer control system 200, wherein the computer control system 200 is configured to receive the three-dimensional mark coordinate measured by the nano-tip sensing device and compare the three-dimensional mark coordinate with a reference coordinate to obtain a displacement difference of the two coordinates in a transverse direction, a longitudinal direction or a circumferential direction, and the displacement difference of the two coordinates in the circumferential direction is a displacement difference of the three-dimensional mark in the circumferential direction. The computer control system is configured to transmit the displacement difference to the displacement driving device 400, and the displacement driving device 400 enables the exposure beam generating device and/or the wafer stage to move correspondingly to reduce the error of two previous exposures and two subsequent exposures of the same wafer region.

The reference coordinates of the utility model are the coordinates of each three-dimensional mark pre-stored in a computer control system in a certain scanning area, or the coordinate measured by the nanometer needle point sensing device before the exposure of the wafer area and the corresponding coordinate in the scanning area after the theoretical distance of the horizontal and vertical movement for realizing the alignment of the next wafer area to be exposed and the projection exposure area are combined, the theoretical distance of the horizontal and vertical movement is stored in the computer control system in advance, if the three-dimensional mark is a spatial pattern of the surface of the photosensitive layer resulting from radiation-induced denaturation of the photosensitive layer (IIRC), the reference coordinates of the three-dimensional marks are parameters such as figures and coordinates of a three-dimensional pattern of an exposed wafer area, which are stored in a computer control system in a scanning area in advance.

Exposure beam that exposure beam generating device sent be at least one of light beam, electron beam, ion beam or atomic beam, the utility model discloses mainly use the optical lithography machine to introduce as the example.

FIG. 2 is a schematic diagram of a photolithography machine according to an embodiment, and particularly shows a schematic diagram of a sub-nanometer step-and-repeat exposure optical photolithography machine. The optical photoetching machine system mainly comprises the following parts:

the light beam generating device comprises a light source 10, a shutter 20, a light beam shaping system 30, a light beam deflection plate or a reflector 40, a shaping lens group 50, a mask plate workpiece table 60 and a projection objective lens group 70. The lithography computer control system 200 may control the shutter 20 and determine the exposure time of the light source.

The wafer stage 100 is used for carrying a wafer 110 to be processed, the wafer includes a plurality of chip regions 120, and a plurality of three-dimensional marks (described in detail later) are disposed on the wafer. The wafer stage 100 comprises a moving part and a fixed part, wherein the moving part comprises a chip area switching driving device 105 and a precision moving device 106, and the fixed part 104 of the chip area switching driving device is located below the chip area switching driving device 105 and is used for carrying the chip area switching driving device 105 and driving the wafer to move in a stepping mode so as to expose different chip areas below the beam generating device in sequence. The computer control system 200 is connected to a wafer area switching driving device 105 for controlling the wafer stage to move precisely, and is used for driving the wafer to move step by step to realize the exposure of all wafer areas. The wafer area switching driving device has a large displacement range, the wafer area switching driving device has a movement distance generally above the micrometer level, and the movement of the current part of the relatively precise wafer area switching driving device can be controlled within 10 nanometers so as to achieve the positioning precision of 2.5 nanometers. The precision moving device 106 is located above the fixing device 107, the fixing device 107 is located above the chip area switching driving device 105, the precision moving device 106 can perform sub-nanometer level fine adjustment on the position of the wafer in the transverse direction, the longitudinal direction or the circumferential direction, and the arrangement of the precision moving device can reduce the dependence of the wafer positioning on the moving precision of the wafer worktable, thereby allowing a wafer worktable with lower moving positioning precision to be used. For example, a wafer worktable with the positioning accuracy of 1 nanometer can be replaced by a wafer worktable with the positioning accuracy of 1000 nanometers, so that the cost of the wafer worktable is greatly reduced.

The nano-tip sensing device 90 comprises tip sensing heads 91 and 92 and micro-cantilevers 91a and 92a connected with the tip sensing heads, wherein the tip sensing heads are positioned above the photosensitive layer of the wafer and used for scanning in a certain scanning area, determining the coordinates of three-dimensional marks in the area and transmitting the obtained signals to the computer control system 200 to be compared with the reference coordinates. The nano-tip sensing device can be fixed on a part close to the wafer but not affecting the positioning of the exposure beam, in this embodiment, the tip sensing heads 91 and 92 are fixed on the side of the lens of the projection objective lens group 70. The tip sensing head moves with the photon beam and, of course, the tip sensing head also drifts with the photon beam. This has the advantage that the microcantilever of the tip sensor head can be made very short, thereby improving the resolution of the three-dimensional measurement of the tip sensor head surface.

In the schematic structure of the lithography machine shown in FIG. 2, the tip sensing heads 91 and 92 fixed on the sides of the beam projection objective lens group 70 are respectively disposed on both sides of the beam projection objective lens group, i.e., one or one row on each side, to form a situation that can cover the areas on both sides of the projection exposure area of the wafer area for measurement. That is, each or each row of the needle tip sensing heads corresponds to two sides of the wafer area in the projection exposure area, and the off-site three-dimensional marks between the wafer areas at the two sides of the wafer area can be measured. The tip sensing heads of each one or each row are mounted on a beam projection objective lens such that their mutual distance is fixed. The coordinates of each other are also fixed. The provision of tip sensing heads on both sides of the wafer area has the advantage of greatly reducing the scanning range of each tip sensing head, i.e. only the middle zone of the respective wafer area needs to be scanned, rather than scanning across the entire wafer area from the middle zone between wafer areas at one end to the middle zone between wafer areas at the other end of the wafer area. Thereby greatly improving the scanning linearity and positioning accuracy of the needle tip sensing head.

The displacement driving means 400 includes a wafer area switching driving means 105 and a nano-displacement driving means 420 which drive stepwise switching of the wafer area. The nano displacement driving device 420 is connected with the computer control system 200, and controls the light beam generating device and/or the fine adjustment of the position of the wafer workbench according to the coordinates of the bottom layer alignment mark measured by the nano needle point sensing device 90, so as to realize the alignment of the wafer area to be exposed and the exposure beam generated by the light beam generating system and complete the exposure. In this embodiment, the nano-displacement driving device 420 can selectively drive at least one of the reflector 40, the shaping lens set 50, the mask plate 60, the projection objective set 70 or the wafer stage 100 to move, so as to achieve fine tuning alignment between the projection exposure region and the wafer region to be exposed.

In this embodiment, a nano-displacement driving device 61 is installed on the mask stage 60 to move the mask laterally, or a nano-displacement driving device 71 capable of driving the lens of the laterally moving lens is installed around the optical projection objective lens group 70, or a nano-displacement driving device 41 capable of moving the photon beam/electron beam or the deflection device 40 laterally is installed around the optical projection objective lens group 70. The position fine adjustment of the projection exposure area can be realized by arbitrarily selecting one of the nano displacement driving devices, and optionally, more than one nano displacement driving device can be arranged on the component.

In order to realize the three-dimensional mark on the wafer, and thus realize the alignment of the wafer area to be exposed and the projection exposure area of the wafer by using the three-dimensional mark on the wafer, an appropriate three-dimensional mark needs to be arranged on the wafer. As will be described in detail below.

Fig. 3 is a schematic diagram illustrating the positions of the preset three-dimensional marks on the wafer. The wafer 110 includes a chip region 120 exposed to light to form a stereoscopic pattern and an off-field region 122 disposed at a periphery of the chip region. Three-dimensional marks may be provided in the wafer area, referred to as in-field three-dimensional marks 1201, or in the field area, referred to as out-of-field three-dimensional marks 1221, which may be provided in the middle zone between adjacent wafer areas or in the wafer edge area. An advantage of off-field three-dimensional marks is that even some destructive processing of these marks does not affect wafer area yield. These marks can be used as alignment coordinate marks by a photon/electron beam exposure, which can be repeatedly "viewed", i.e. exposed, with a photon/electron beam.

The in-field three-dimensional mark 1201 includes a nanoscale three-dimensional mark previously set before the first processing step in the wafer region, or may be a three-dimensional mark of a three-dimensional pattern generated on a photosensitive layer on the surface of the wafer region after a photosensitive layer is coated on the wafer and exposed by a light beam. The in-field three-dimensional mark 1201 can be as small as a few nanometers to a few hundred nanometers, and since the occupied area is small, the yield of the wafer area is not affected even if the mark is made in the wafer area.

The coordinate relationship between the three-dimensional marks and each chip area can be fixed through one-time measurement of the wafer, and the accurate coordinate position of the chip area can be positioned only by measuring the three-dimensional marks. The positioning between these coordinates can be easily accurate to single or sub-nanometer scale, provided that the wafer is not deformed by thermal expansion and contraction through precise temperature control over a relatively long period of time.

The first measurement of the three-dimensional marks and the position of the chip area determines the relative deviation of the wafer with respect to the wafer stage, and particularly determines whether the wafer needs to be rotated to adjust the parallelism of the wafer stage with the array of chip areas on the wafer while the wafer stage is moving. The computer control system 200 controls each component of the lithography machine through the off-field three-dimensional marks and the in-field three-dimensional marks of the wafer region and realizes sub-nanometer scale longitudinal alignment and exposure of the wafer region through a preset control method.

The closer the three-dimensional mark is to the wafer area being exposed, the higher the alignment accuracy for the wafer area. Three-dimensional marks 1221 between wafer areas are set between wafer areas. This arrangement of three-dimensional marks is suitable for use in a step-and-repeat exposure lithography machine. However, for a direct-write photon beam/electron beam lithography machine of the non-mask type, there are many cases where it is practically not allowed to leave space between the exposed write fields. A grating or fresnel lens is an example.

The utility model discloses the utilization can perceive three-dimensional nanometer structure's measurement technique, if use needle point sensing head sensing technique can realize the three-dimensional appearance measurement technique of sub-nanometer (the three-dimensional appearance measurement technique of atomic force of sub-nanometer), the utility model discloses set up three-dimensional mark on the wafer, this three-dimensional mark passes through needle point sensing head sensing technique and measures and realize the coordinate location. The three-dimensional marks on the photosensitive layer and the wafer surface can be used as alignment marks, and a precise alignment coordinate can be determined by measuring the peak position or the valley position of the three-dimensional marks. The concave-convex structure on the surface of the wafer generally causes the surface of the photosensitive layer covered on the wafer to follow and form the concave-convex structure, namely, the positioning can vertically penetrate through the concave-convex structure, so that the surface of the photosensitive layer covered on the surface can be measured due to the concave-convex structure.

The wafer include that a plurality of chips are regional, the regional inside of chip or set up an at least bottom alignment mark around the chip region, the wafer surface sets up photosensitive layer, bottom alignment mark is in form the three-dimensional mark that corresponds on the photosensitive layer, three-dimensional mark have with the upper surface on photosensitive layer is not in the region of same horizontal plane.

Fig. 4A, 4B and 4C respectively show an embodiment of providing three-dimensional marks on a wafer.

Fig. 4A shows a convex three-dimensional mark schematic diagram, firstly, more than one bottom layer alignment mark protrusion 45a (hamw) is disposed on the wafer by deposition, etc., which is the preset nanometer level bottom layer alignment mark, then the photosensitive layer is disposed above the wafer, since the photosensitive layer has certain fluidity and is soft, the bottom layer alignment mark protrusion 45a (hamw) will form a corresponding protrusion structure 46a (hamr) on the upper surface of the photosensitive layer, and the protrusion structure is the three-dimensional mark of the present invention. If the thickness of the photosensitive layer is between 10 nm and 100 nm, the surface layer of the photosensitive layer on the bottom alignment mark 45a (HAMW) of the wafer will also follow to become a three-dimensional mark. The height of this three-dimensional mark can accordingly be in the range of a few nanometers to a few tens of nanometers, usually less than 100 nanometers, giving it exactly the position on the surface of the photosensitive layer as a three-dimensional mark. This position is exactly the same in the vertical direction as the position of the underlying alignment mark of the wafer vertically below. In this way we can accurately determine the lateral coordinates of the wafer pattern, which is important to be placed within the die area (write field). The provision of these three-dimensional marks can determine the accuracy of the alignment so that the alignment is not dependent on the accuracy of the movement of the wafer stage. Thereby allowing the use of a single wafer stage with low positional accuracy. For example, a wafer worktable with the positioning accuracy of 1 nanometer can be replaced by a wafer worktable with the positioning accuracy of 1000 nanometers, so that the cost of the wafer worktable is greatly reduced.

Three-dimensional mark and photosensitive layer have at least partial region to be located different horizontal planes, for example in this embodiment, this three-dimensional mark 46a have the protrusion in photosensitive layer's point form is protruding, when the wafer that is equipped with this three-dimensional mark is arranged in the utility model discloses a when the photoetching machine was built, nanometer needle point sensing device's needle point sensing head scans in certain scanning area, because there is extremely weak repulsion force between the most advanced atom of needle point sensing head and wafer surface atom, little cantilever will be corresponding to needle point sensing head and wafer surface atom between the equipotential surface of acting force and at the surperficial direction fluctuation motion of perpendicular to wafer. The position change of the micro-cantilever corresponding to each scanning point can be measured by an optical detection method or a tunnel current detection method, so that the information of the surface topography of the wafer can be obtained. The utility model discloses in, it is protruding to utilize the three-dimensional mark to have a point form, and this point form is protruding to the distance of needle point sensing head and photosensitive layer upper surface are different to the distance of needle point sensing head, to the location of three-dimensional mark when realizing the scanning of needle point sensing head. In order to accurately identify the coordinates of the three-dimensional mark, the utility model discloses the height of the three-dimensional mark who sets up is greater than the surface roughness of photosensitive layer, an optional height is less than or equal to 50 microns.

Fig. 4B is a schematic diagram of a three-dimensional structure marked as a concave portion on the surface of a wafer, and additional material is required on the wafer to realize the three-dimensional convex structure shown in fig. 4A. In contrast, the wafer is etched to form the inverted three-dimensional "protruding" structures 45b, i.e., recessed structures, which have the advantage of not depositing additional material on the wafer, but rather "digging" away material from the existing wafer, which is easier than fabricating three-dimensional protruding structures. According to the above description, since the three-dimensional mark 46b corresponding to the depression formed on the photosensitive layer can measure the whole three-dimensional structure by the atomic force microscope of the tip sensing head, even if the pit of the three-dimensional structure has a size of several nanometers at the tip thereof, all the three-dimensional shape information of the structure can improve the positioning to a single nanometer level.

Fig. 4C is a schematic diagram of a nanoscale concave-convex three-dimensional mark structure on the surface of a wafer etched by an etching technique. The three-dimensional protruding structure can be obtained as the nanometer three-dimensional mark without adding other materials deposited on the wafer, in this embodiment, the bottom alignment mark 45c on the wafer comprises more than one point-shaped structure, and the corresponding three-dimensional mark 46c on the photosensitive layer also has more than one point-shaped structure, so that the needle tip sensing head can realize more accurate positioning.

In order to achieve a three-dimensional mark that can accurately locate the wafer coordinates, the three-dimensional mark described by the present invention optionally has certain graphical features that, in addition to including at least one dot feature 44, include ridge features 43 connected to the dot feature, the dot feature and the ridge features not being completely in the same plane as the upper surface of the photosensitive layer. FIG. 4D shows a schematic diagram of a three-dimensional prismatic structure that increases the detectable area of the three-dimensional mark and improves the accuracy of the positioning of the three-dimensional mark by adding several ridge features 43 that are located in different horizontal planes from the photosensitive layer.

In the above embodiment, a protruding or recessed nano three-dimensional structure, such as a micro cone, a micro pyramid or a micro tip sensor head, is pre-arranged on the surface of the wafer. The diameter scale of which is from a few nanometers to tens of nanometers, typically less than 100 nanometers. These microstructures may be realized by plasma etching techniques or electron beam induced deposition techniques (EBID).

The utility model discloses can set up a plurality of three-dimensional marks on the wafer, an optional mode does, every wafer region corresponds and sets up at least one three-dimensional mark, this three-dimensional mark can be for setting up at the regional inside three-dimensional mark in the scene of wafer, also can be for setting up the regional three-dimensional mark outside the scene around the wafer region, including two horizontal adjacent or two vertical adjacent wafer regions between the region around this wafer region, or the edge of wafer and the regional relative position of wafer etc. optional, the three-dimensional mark coordinate that every wafer region corresponds is fixed rather than the regional relative position of wafer. The three-dimensional marks shown in fig. 4A-4D described above are three-dimensional marks for setting absolute positions on a wafer, and in addition, the wafer can be positioned by using a tip sensor head sensing technology according to the shape of a specific photosensitive layer after exposure through the characteristics of the photosensitive layer. The alignment precision of the wafer area is improved by the position positioning of the relative marks.

The bottom layer alignment mark comprises a mark which is manufactured on the surface of the wafer before the first exposure of the wafer and also comprises a mark which is arranged below the photosensitive layer in the subsequent exposure process, and the bottom layer alignment mark can be manufactured again after certain steps of processes are carried out in consideration of weakening of point-like features and ridge features of the three-dimensional mark caused by possible loss of the three-dimensional mark in the process of pattern transfer so as to improve the positioning accuracy of the three-dimensional mark on the surface of the subsequent photosensitive layer.

Fig. 5A shows a schematic view of a pattern of Irradiation Induced photosensitive layer modification (IIRC), which means that the chemical and/or physical properties of the photosensitive layer are changed at the position of Irradiation exposure by a photon beam or electron beam or other particle beam. The chemical change includes a chemical reaction of the surface of the photosensitive layer by the photon beam/electron beam, resulting in a change of the irradiated photosensitive layer portion from an insoluble state to a soluble state upon development (positive glue), or a soluble state to an insoluble state by exposure (negative glue). Physical changes of the photosensitive layer, including slight changes in the surface geometry of the photosensitive layer, are also caused by the photon beam/electron beam exposure, and when the photon beam/electron beam exposure transfers exposure pattern information to the photosensitive layer, a change in the relief structure of the photosensitive layer is generated. Such as the exposed regions expanding on a sub-nanometer scale or nanometer scale, forming raised regions 47a relative to the unexposed regions 48a, see fig. 5A; or the exposed areas shrink to form a recessed structure, see fig. 5B, forming recessed areas 47B and unexposed areas 48B, the tip sensor head sensing technology can be used to locate a certain wafer area by measuring the protruding areas 47a and the recessed areas 47B. This deformation can be sensed by probing the tip sensor head (highly sensitive sensor head) at a sub-nanometer scale.

In order to ensure the positioning accuracy of the IIRC mark shown in fig. 5A and 5B, several three-dimensional marks, for example, three or more three-dimensional marks, may be disposed on the edge of the wafer, and the position of the entire wafer may be determined by the three-dimensional marks. The absolute position of the wafer is then measured and located by the tip sensing head. A combination of multiple tip sensing heads may be used, such as a linear array of multiple tip sensing heads may be used to transfer the coordinates of the absolute three-dimensional marks at the edge of the wafer to the center of the wafer. The linear tip sensor array greatly expands the range of the tip sensor for measuring wafers without errors. The mutual distance between the needle tip sensing heads on the one-dimensional linear needle tip sensing head array is fixed. The movement of the needle tip sensing head uniformly moves the linear arrays through piezoelectric displacement at the two ends of the linear arrays or a voice coil driving system. The relative coordinate position between the tip sensing heads is not changed.

The exposure of the next chip region can be aligned by using the three-dimensional pattern mark generated by the self-exposure of the chip region, and a positioning mark generating device (not shown in the figure) can be arranged on the exposure beam generating device, the positioning mark generating device forms a three-dimensional positioning mark on the periphery of the wafer region while exposing the chip region, and the needle tip sensing head performs positioning and calibration on the position of the chip region to be exposed according to the three-dimensional positioning mark. For example, in an optical lithography system, one or more positioning mark generating devices may be disposed at the periphery of a normal pattern of a mask plate, and when a wafer region to be exposed is exposed, a three-dimensional positioning mark is simultaneously exposed at the edge of the wafer region, and the three-dimensional positioning mark is optionally located between two wafer regions, so as to reduce the scanning area of a needle tip sensing head and improve the positioning efficiency. When the next wafer area is exposed, the computer control system 200 aligns the wafer area to be exposed and the projection exposure area by using the nano-displacement driving device according to the coordinates of the three-dimensional positioning mark corresponding to the previous wafer area scanned by the needle point sensing head.

Fig. 6 is a schematic structural diagram of a lithography machine according to another embodiment of the present invention, in which a nano-tip sensing device is disposed on a wafer stage 100, the wafer stage 100 includes a moving part and a fixed part, and the 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 placed between wafer regions and/or to measure the pattern structure and coordinate positions of the wafer regions in the wafer regions before exposure. Then, the wafer area switching driving device 105 drives the wafer stage 110 to move laterally, so as to leave out the projection exposure area for the next wafer area for exposure, and the movement also brings the writing field movement error. The probe tip sensing head measures new coordinate values of the three-dimensional mark outside the wafer area and/or on the inner surface of the wafer area brought by the movement of the wafer worktable, and the new coordinate values can be compared with the coordinate values of the original three-dimensional mark to give the movement amount of the movement error XY coordinate (and XY plane angle) of the wafer area. This amount can be used for repositioning the wafer stage and also for moving objects affecting the photon beam, such as a mask or a projection objective lens, by several nanometers. In the embodiment, the needle tip sensing head sensing technology is arranged on the wafer workbench, so that the three-dimensional marks of the edge area of the wafer can be conveniently measured, and the accurate position of the whole wafer can be determined only by a plurality of three-dimensional marks due to the large distance between the three-dimensional marks of the edge area of the wafer.

The problem with this method and apparatus is that the wafer stage is large in size, typically over 200 mm. Thus, the microcantilever connecting the tip sensing head to the base holding the tip sensing head is very long. The long microcantilever may reduce the resolution of the three-dimensional measurement of the tip sensor surface, and thus may improve this embodiment.

Fig. 7 is a schematic structural diagram of a lithography machine according to another embodiment of the present invention, in which the nanotip sensing device combines the fixed position features of fig. 2 and 6. One set of tip sensing heads 93 and 94 is mounted on the wafer stage and the other set of tip sensing heads 91 and 92 is mounted on one side of the photon beam, e.g., on both sides of the projection objective lens. The method has the advantages that the coordinates of the off-field three-dimensional marks corresponding to the wafer area to be exposed can be accurately measured, and meanwhile, the accurate position of the whole wafer can be determined only through a plurality of three-dimensional marks.

Fig. 8 is a schematic diagram of a plurality of tip sensing heads and wafer area mapping according to an embodiment of the present invention, wherein the coordinate position of each wafer area is measured and determined by the plurality of tip sensing heads. In this embodiment, the plurality of tip sensing heads 91, 92, … … 9n are fixedly attached by connectors 140 and arranged in a row across the wafer area to form a lateral tip sensing head array. According to the above description, in the preparation step, at least one bottom alignment mark is disposed on a wafer to be processed, and the bottom alignment mark correspondingly forms a three-dimensional mark on the photosensitive layer; when exposing the wafer, placing the wafer with the three-dimensional mark in the preparation step into the photoetching machine, wherein a projection objective lens group 70 is arranged in the photoetching machine close to the wafer, corresponds to a projection exposure area on the wafer, and drives a wafer area switching driving device 105 of the wafer workbench to place a first wafer area to be exposed below the projection objective lens group; scanning the photosensitive layer in a certain scanning area by using at least one of the needle tip sensing heads 91-9n to obtain the position coordinates of a first three-dimensional mark, such as the three-dimensional mark 1221, and comparing the position coordinates of the first three-dimensional mark with the reference coordinates of the first three-dimensional mark to obtain the difference value of the two position coordinates; the displacement driving device adjusts the relative positions of the exposure beam generating device and the wafer worktable according to the difference value of the two position coordinates, so that the projection exposure area is aligned with the first wafer area, and the 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 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.

After the exposure of the first wafer area is completed, the second wafer area is placed below the projection objective lens group, and at this time, the alignment of the first wafer area and the projection exposure area can be realized by various alignment marks. One way is as follows: the needle point sensing head scans the position coordinates of the first three-dimensional mark after moving and compares the position coordinates with the reference coordinates of the first three-dimensional mark after moving to obtain the deviation of the two position coordinates, the reference coordinates of the first three-dimensional mark after moving are the coordinates corresponding to the scanning area after the distance of the wafer which is moved in the horizontal and vertical directions is combined with the projection exposure area in order to realize the alignment of the position coordinates of the first three-dimensional mark and the next wafer area which needs to be exposed when the first wafer area is exposed. The distance of the wafer to be moved in the transverse direction and the longitudinal direction is predetermined according to parameters such as the size of a chip area generated by exposure, the distance between two adjacent chip areas and the like and is stored in a computer system. The positioning after one or more steps of moving a three-dimensional mark that realizes accurate positioning at the time of exposure of the wafer area of the previous step can accurately determine its reference coordinates according to the number of the wafer areas moved. When the same three-dimensional mark is used for alignment, the number of the needle point sensing heads and the range of a scanning area need to be considered, because the same three-dimensional mark needs to be tracked and scanned, two needle point sensing heads are optionally arranged to respectively carry out coordinate measurement on the three-dimensional mark before the exposure of a chip area and the same three-dimensional mark after the movement of a wafer on two sides, and the other optional mode is that one needle point sensing head with a larger scanning range is selected to realize the tracking and scanning of the same three-dimensional mark.

The other alignment mode is as follows: after the exposure of the first wafer area is finished, the second wafer area is arranged below the projection objective lens group, the needle tip sensing head scans the position coordinates of a second three-dimensional mark and compares the position coordinates with the reference coordinates of the second three-dimensional mark to obtain the deviation of the two position coordinates, the displacement driving device adjusts the relative positions of the exposure beam generating device and the wafer workbench according to the difference value of the position coordinates, so that the projection exposure area is aligned with the second wafer area, 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. In order to maintain the alignment accuracy, optionally, the first three-dimensional mark is disposed near the first wafer region, and the second three-dimensional mark is disposed near the second wafer region.

The third alignment method is: after the exposure of the first wafer area is finished, the second wafer area is arranged below the projection objective lens group, the needle tip sensing head scans the graph and the coordinate of a three-dimensional pattern formed on the photosensitive layer after the exposure of the first wafer area and compares the graph and the coordinate with a reference graph and a coordinate of the three-dimensional pattern which are pre-stored in a computer control system to obtain the position difference value of the two three-dimensional patterns, and the displacement driving device adjusts the relative positions of the exposure beam generating device and the wafer worktable according to the position difference value to align the projection exposure area with the second wafer area and realize the exposure of the second wafer area.

The three alignment modes may be selected according to whether a three-dimensional mark generated by the bottom layer alignment mark is arranged near the wafer region, or two or more alignment modes may be selected to improve the alignment accuracy. When a certain wafer area is aligned, more than one three-dimensional mark coordinate can be scanned at the same time and compared with the corresponding reference coordinate to improve the alignment precision.

The third wafer area and the subsequent wafer area are sequentially exposed below the projection objective lens group, and exposure is realized according to the alignment method.

Optionally, the nano needle tip sensing device is fixed on one side or two sides of the projection objective lens group, and is relatively fixed with the projection objective lens group. When the same three-dimensional mark is used for alignment, the number of the needle point sensing heads and the range of a scanning area need to be considered, because the same three-dimensional mark needs to be tracked and scanned, two needle point sensing heads are optionally arranged to respectively carry out coordinate measurement on the three-dimensional mark before the exposure of a chip area and the same three-dimensional mark after the movement of a wafer on two sides, and the other optional mode is that one needle point sensing head with a larger scanning range is selected to realize the tracking and scanning of the same three-dimensional mark. When two or more tip sensing heads are provided, the distance between two adjacent tip sensing heads is equal to the sum of the lateral width of one wafer region and the width of the off-field region between two wafer regions, and optionally, the distance between two adjacent tip sensing heads is a multiple of the sum of the two distances. The design can ensure that the needle point sensing head can scan in a smaller range to realize the accurate positioning of the three-dimensional mark when the wafer area is exposed in sequence. The positions of the plurality of needle point sensing heads are relatively fixed through the connecting piece, so that the transmission of the coordinate positioning of a certain three-dimensional mark on the wafer to the positions of other wafer areas on the transverse needle point sensing head array is realized. At the moment, the accurate positioning of the wafer coordinate measured by any one needle point sensing head can be transmitted to the coordinate positioning measured by other needle point sensing heads, and no error exists in the transmission process.

The spacing between the tip sensing heads may be greater than or equal to the size of the die area plus the inter-die area distance, such that one tip sensing head measures the three-dimensional mark coordinate position at or near the edge of the wafer, another tip sensing head measures the three-dimensional mark at the middle zone between the die areas, and yet another tip sensing head measures the middle zone between the die areas of another die area, and so on.

Specifically, the first needle point sensing head measures the position of a three-dimensional mark on the edge of the wafer, and the transverse needle point sensing head array transmits the absolute value of the position to the second needle point sensing head, so that the position of the second needle point sensing head can determine absolute coordinates without arranging the three-dimensional mark on the wafer. The coordinates of the first tip sensing head may also be transmitted further into the wafer through the nth tip sensing head until the last tip sensing head. And the last tip sensor head may typically transmit a three-dimensional mark measured onto the other edge of the wafer. The chip area to which the needle point sensing head can not move can transmit the exposure coordinate positioning of a plurality of chip areas by a transverse writing field splicing method, and excessive positioning coordinate error accumulation is avoided due to limited transmission quantity, so that a scene that all chip areas on a wafer can be aligned, positioned and accurately aligned with exposure can be formed.

The nanometer grade three-dimensional mark on the edge of the wafer is realized by utilizing the needle tip sensing head array, or the nanometer grade three-dimensional mark coordinate in the middle of the wafer and the relative position of the light beam are positioned, and at least three-dimensional marks are required to be used for ensuring the positioning of the wafer relative to the light beam. The more widely the three-dimensional marks are distributed on the wafer, the more accurately the wafer can be positioned. Fig. 9 is an L-shaped multi-tip sensor array. The array can be located using three-dimensional marks at very large wafer edges as accurate coordinates for the wafer.

Fig. 9 is a schematic diagram illustrating a plurality of needle tip sensing heads and a corresponding relationship between the wafer areas according to an embodiment of the present invention, in this embodiment, the plurality of needle tip sensing heads are connected by a connecting member 150 and arranged in an L-shaped array, and at least one needle tip sensing head 101 capable of measuring three-dimensional marks in other rows of the edge area is added on the basis of the disclosed horizontal needle tip sensing head array of the embodiment shown in fig. 8, and the L-shaped array can be positioned by using three-dimensional marks at the very large wafer edge as accurate coordinates of the wafer.

The probe tip sensing head array is one of the most accurate positioning methods to realize the positioning of the relative positions of the nanoscale three-dimensional marks and the light beams at the two ends of the edge of the wafer. Fig. 10 is a schematic diagram illustrating the correspondence between a plurality of tip sensing heads and a wafer area according to an embodiment of the present invention, in this embodiment, the plurality of tip sensing heads are connected to form a U-shaped array through a connecting member 160, and at least one tip sensing head 111 capable of measuring three-dimensional marks of other rows in the edge area is respectively added to both ends of the disclosed lateral tip sensing head array of the embodiment shown in fig. 8. Therefore, the accurate coordinate position of the wafer relative to the exposure light beam can be determined by the nanoscale three-dimensional marks which are respectively arranged at more than three distances apart at the edges of the two ends of the wafer. The array can be located using three-dimensional marks at the two ends of the wafer that are very far apart as the exact coordinates of the wafer. The arms of the U may not be the same length. The needle tip sensing head linear array can be fixed on a light beam projection objective lens group and also can be fixed on a wafer worktable.

The needle tip sensing head can measure the surface structure of the wafer in the atmosphere or vacuum environment, and can also be immersed in liquid in the immersion environment to measure the surface structure of the wafer. For immersion lithography, the three-dimensional marks measured by the tip sensing head may be three-dimensional marks in an immersion environment, or three-dimensional marks corresponding to regions of the wafer that correspond to adjacent regions of the wafer outside the exposure beam that are not in an immersion environment.

The surface structure data of the three-dimensional mark detected by the needle tip sensing head is a mathematical convolution of the surface structure of the three-dimensional mark and the needle tip structure of the needle tip sensing head, so that the shape of the needle tip sensing head may influence the surface structure data of the three-dimensional mark detected by the needle tip sensing head, and the needle tip structure needs to be measured and calibrated before the three-dimensional mark is measured by the needle tip sensing head, so that the measurement accuracy is improved.

The foregoing description mainly includes adjusting the position of the wafer in the lateral, longitudinal, or circumferential direction to achieve alignment with the projection exposure area, in some cases, the wafer may deviate from the verticality of the exposure beam, for example, the wafer that should be horizontally disposed may be inclined at a certain angle, in order to detect this, three or more needle point sensing heads may be disposed, and three or more needle point sensing heads are disposed on different straight lines, when three or more needle point sensing heads measure three-dimensional marks in respective scanning areas, it may be determined whether the wafer area where the three-dimensional mark is located is inclined according to the height difference of the three-dimensional mark that is identified, so that the distance between the wafer area and the sensing needle point head is changed. And driving the wafer worktable to adjust the wafer to be vertical to the exposure beam through a computer control system according to the measured height difference.

Utilize the alignment device to realize the alignment method for the regional alignment of the sub-nanometer level high-precision photoetching wafer, which comprises the following earlier preparation steps:

preparation step 1, light beam positioning preparation. The needle tip sensing head is fixed at the side of the projection objective lens group of the exposure beam generating device, so that the relative position of the needle tip sensing head and the exposure beam is fixed. Thus, the coordinate system of the needle tip sensing head is the coordinate system of the exposure beam projection exposure area which is fixedly translated. A wafer (which may be a wafer with test structures) coated with a photosensitive layer is first aligned. A mask with a sufficiently fine structure is used as the calibration mask. And exposing a light beam through a mask plate, wherein the pattern of the mask plate is transferred to the photosensitive layer on the surface of the wafer and forms a chip area pattern area on the photosensitive layer, and a three-dimensional pattern on the surface of the photosensitive layer is generated due to irradiation induced photosensitive layer degeneration (IIRC). The three-dimensional pattern is the projection coordinate position of the light beam on the surface of the wafer. The three-dimensional mark outside the wafer area and the IIRC three-dimensional pattern mark in the wafer area are measured by the needle tip sensing head, and the coordinate position of the light beam projection exposure area and the coordinate position of the needle tip sensing head are relatively fixed.

The needle tip sensing head is linked with the coordinates of the projection objective lens group (namely, the light beam projection pattern). When the positioning of the wafer area is measured using the tip sensing head, the exact position of the wafer area is found, just like the eye of the exposure beam.

And 2, preparing a wafer, namely measuring the three-dimensional mark coordinate position of each chip area by using a needle tip sensing head before or after the wafer is coated with the photosensitive layer so as to determine the mutual position of each off-field three-dimensional mark coordinate.

And 3, a preparation step of finding out the coordinate position of the projection exposure area of each chip area on the wafer for the first time.

The method comprises the following steps: before the wafer is not subjected to photoetching exposure, no pattern is formed on the wafer, so that the alignment problem that the pattern is left on the wafer by the projection exposure area and the previous exposure does not exist. A first wafer area pattern area may be formed simply by a beam projection exposure and then the wafer stage moved to the next wafer area exposure pattern until all patterns on the wafer have been exposed. The three-dimensional mark coordinates outside the wafer area and the position coordinates of the projection exposure area of the wafer area can be related by measuring the three-dimensional mark coordinates of the three-dimensional pattern in the field obtained by measuring the photosensitive layer variation (IIRC) of the projection exposure area of the wafer area through the needle tip sensing head. The position of the projection exposure area can be determined by measuring the coordinates of the off-site three-dimensional mark of the wafer area.

The second method comprises the following steps: after the first exposure of the wafer, the exposure pattern on the photosensitive layer is transferred to the wafer, for example, by a plasma etching method, and the coordinate of the three-dimensional mark outside the wafer area and the coordinate position of the three-dimensional mark of the three-dimensional pattern of the wafer area are directly measured and recorded, so that the position of the projection exposure area of the wafer area can be calculated by measuring the coordinate of the three-dimensional mark outside the wafer area in the future. The measurement may be by a tip sensing head, or by other measuring instruments than a lithography machine.

The preparation step 1, the preparation step 2 and the preparation step 3 are disposable. After the wafer is initially measured once, the off-site three-dimensional markers can be used to determine the coordinate locations of the die regions.

Wafer area coordinate reference points. Through the preparation steps, the wafer area coordinates are associated with the off-field three-dimensional mark coordinates of each wafer area. And determining the coordinate of the off-field three-dimensional mark, namely determining the position coordinate of the wafer area.

A preparation step 4, if the measured arrangement array of each chip area on the wafer has angular deviation with the wafer worktable for bearing the wafer, the angle error of the wafer and the wafer worktable in the horizontal two-dimensional moving direction, namely the circumferential direction, needs to be calibrated. After the preparation steps are completed, starting to enter a wafer area alignment step:

alignment step 1, the first wafer area overlay alignment process begins. The wafer 110 coated with the photosensitive layer 120 is placed on the wafer worktable 100, the off-field three-dimensional mark of the wafer area is measured by the needle tip sensing head fixed on the beam projection objective lens group 70, and the position of the light beam facing the wafer area pattern area can be determined by utilizing the fixed coordinate relationship between the off-field three-dimensional mark coordinate obtained in the preparation step 3 and the wafer area pattern area. Thus, the coordinate deviation of the beam projection exposure area from the position of the pattern area of the wafer area, i.e., (Δ X)₁，ΔY₁)。

Alignment step 2, using a nano-displacement driving device 61 fixed with the mask plate to drive the mask plate to moveAligning the coordinates (Δ X) obtained in step 1₁，ΔY₁) And performing corresponding opposite compensation movement on the mask plate according to the error amount. So that the projected exposure area is aligned with the pattern area location of the wafer area.

And 3, alignment step, namely exposing the first wafer area in the projection exposure area.

An alignment step 4, starting the needle tip sensing head to measure the coordinates of the exposed three-dimensional mark outside the wafer area and the position of the IIRC three-dimensional pattern in the wafer area; this is equivalent to re-measuring the wafer area coordinate position and the beam projection exposure field position, and instantaneously calibrating the wafer area position and the beam projection exposure field position. This allows for correction by this step even if some parts of the lithography machine drift slightly over time.

And 5, alignment step, namely, preparation before exposure of the second wafer area is carried out. The wafer stage 100 is moved to move the wafer 110 laterally, so that the first wafer region that has just been exposed moves out of the projection exposure area to become a wafer region with a three-dimensional pattern, thereby making room for the second wafer region of the following wafer to enter the projection exposure area. The movement of the wafer stage can cause wafer area positioning errors;

an alignment step 6, starting the needle point sensing head to measure and identify the corresponding off-field three-dimensional mark coordinate of the second wafer area, comparing the off-field three-dimensional mark coordinate and/or the three-dimensional pattern three-dimensional mark coordinate of the IIRC in the field related to the first wafer area moving out of the projection exposure area to obtain the deviation (delta X) of the second wafer area needing to move₂，ΔY₂)；

An alignment step 7 of obtaining the coordinates (Δ X) according to the alignment step 6 by using a nano-displacement driving device 61 fixed to the mask plate₂，ΔY₂) The mask plate is driven to make relative compensation movement according to the error amount. So that the beam projection exposure area is aligned with the pattern area position under the photosensitive layer of the wafer area.

And 8, carrying out exposure on the second wafer area in the projection exposure area.

An alignment step 9, enabling the needle tip sensing head to measure the coordinates of the exposed three-dimensional mark outside the wafer area field or/and the position of the IIRC three-dimensional pattern mark inside the wafer area field;

alignment step 10, preparation before exposure of the third wafer area is performed. The wafer stage 100 drives the wafer 110 to move laterally, so that the second wafer region that has just been exposed moves out of the projection exposure region to become a wafer region with a three-dimensional pattern, and a space is made for the third wafer region of the following wafer to enter the projection exposure region; movement of the wafer stage can introduce wafer area positioning errors.

An alignment step 11, which is to start the needle tip sensing head to measure and recognize the three-dimensional mark coordinate outside the field associated with the third wafer area and to measure the three-dimensional pattern mark of IIRC in the second wafer area of the shift-out projection exposure area, and to compare the three-dimensional mark coordinate outside the field associated with the first wafer area of the shift-out projection exposure area and/or the three-dimensional pattern mark coordinate of IIRC in the field to obtain the deviation (DeltaX) of the second wafer area needing to be shifted₃，ΔY₃)；

An alignment step 12 of obtaining the coordinates (Δ X) according to the alignment step 11 using a nano-displacement driving device 61 fixed to the mask plate₃，ΔY₃) The mask plate is driven to make relative compensation movement according to the error amount. So that the beam projection exposure field is aligned with the pattern position of the wafer area.

And 13, repeating the steps to complete the exposure, movement and alignment of the whole wafer chip area.

The three-dimensional mark for alignment described in this embodiment can be not only an off-field three-dimensional mark in the middle zone between the wafer area to be exposed and the adjacent wafer area, but also an IIRC three-dimensional pattern three-dimensional mark on the surface of the previously exposed wafer area (coated with a photosensitive layer) as a coordinate reference system for the next wafer area exposure. Since no three-dimensional marks need to be set between chip areas by using the IIRC, the setting of three-dimensional marks between chip areas can be greatly reduced. However, the use of the IIRC solid pattern three-dimensional mark as the coordinate system of the last exposed wafer area results in the accumulation of errors in the measurement of each exposed wafer area by the tip sensing head. Therefore, the wafer area provided with the corresponding three-dimensional mark and the wafer area not provided with the corresponding off-field three-dimensional mark are generally arranged at intervals, and the off-field three-dimensional mark among a plurality of wafer areas is saved by using a plurality of IIRC graphs as reference points for aligning and positioning the projection exposure area, and meanwhile, the accumulated total error is ensured to be within an allowable range.

In the embodiments of the present invention shown in fig. 8-10, a linear array having a plurality of tip sensing heads is combined with an off-wafer field three-dimensional mark along with an on-wafer field IIRC three-dimensional mark, and the number of off-field three-dimensional marks can be set in a smaller amount. Specifically, the lateral tip sensor array directly ties the movement error of a first tip sensor with other tip sensors mounted on the linear array of tip sensors to the position of the first tip sensor, spanning the accumulation of errors that may occur in the middle multiple wafer regions due to the lack of use of three-dimensional markings in the middle zone between adjacent wafer regions to confirm wafer region positioning.

In another embodiment, the nanometer three-dimensional mark can be arranged on the edge of the wafer only, and then the coordinate position in the wafer is directly connected to the three-dimensional mark coordinate position of the wafer area identified by the edge of the wafer through a plurality of linear arrays of the needle tip sensing heads, so that the error accumulation caused by the front and back exposure of a plurality of middle wafer areas and the reference to the previous wafer area exposure is eliminated.

Through the description above, the utility model discloses an improve the alignment precision of wafer when marching type exposes to the sun, mainly realize through following technical scheme:

the technology of measuring the actual coordinate position of a wafer area/writing field with sub-nanometer precision.

The method adopts a needle tip sensing head sensing technology, including a needle tip sensing head atomic force microscopy technology. Atomic force microscopy is one of the tip sensing head sensing technologies. The method can measure the surface three-dimensional morphology of the wafer with sub-nanometer precision, the nanometer distribution of the surface work function and the like.

Second, the sub-nanometer displacement driving technique of the object.

The first technique is a piezoelectric ceramic technique that moves sub-nanometer steps. Sub-nanometer scale movement can be generated using piezoelectric principles. However, typical piezoelectric displacements are nonlinear and have hysteresis loops.

The second technique is an electromagnetic drive technique. A Voice Coil Motor (Voice Coil Motor) is a special form of direct drive Motor. The device has the characteristics of simple structure, small volume, high speed, high acceleration, quick response and the like. The positioning precision can reach 1/30 nanometer level. The principle of operation is that an energized coil (conductor) placed in a magnetic field produces a force whose magnitude is proportional to the current applied to the coil. The motion form of the voice coil motor manufactured based on the principle can be a straight line or a circular arc. Both techniques may be used in the present invention.

And thirdly, a sub-nanometer displacement driving and positioning technology of the object.

With the above measurement and driving techniques, sub-nanometer positioning can be achieved. The positioning is to make the chip area/write field of the wafer perform positioning displacement adjustment in nanometer level relative to the photon beam/electron beam to eliminate the relative coordinate shift caused by the movement of the wafer stage or the movement of the photon beam/electron beam. Therefore, the method and the device for correcting the position error of the wafer area/writing field with deviation relative to the position of the photon beam/electron beam can be provided, so as to realize the transverse splicing and the longitudinal alignment of the sub-nanometer wafer area/writing field. Examples of implementations of displacement driving and positioning of an object:

a. in the photon beam/electron beam lithography machine, a sub-nanometer level positioning wafer work table can be used, or a more accurate pico-meter small wafer work table is arranged on the existing wafer work table for accurate positioning, namely the moving step length of the wafer work table is smaller than that of the existing wafer work table. (the small wafer stage may be slower in moving speed).

b. In a photon beam/electron beam lithography machine using a mask plate, a driving device for driving the nano-scale movement of a mask plate workpiece stage may be provided, and the nano-scale movement of a photon beam/electron beam projection objective lens group may be provided, which is sufficient to achieve the correction of the alignment error of the wafer area/write field.

c. In a photon beam/electron beam direct writing lithography machine, it is possible to set the displacement of the photon beam/electron beam projection objective lens set so that the lens can move several and several tens of nanometers, which is sufficient to correct the alignment positioning error relative to the writing field/wafer area.

d. In a photon beam/electron beam direct writing or mask plate lithography machine, driving the photon beam/electron beam itself or a deflection device may be provided to effect displacement and coordinate correction of the photon beam and electron beam.

And fourthly, providing a device and a method for closed-loop control type measurement and alignment and then exposure of a wafer area in a photoetching machine.

The utility model discloses a lithography machine alignment system possess the measurement-removal-remeasurement closed-loop control characteristics of the regional alignment of wafer, and the regional method of specifically aligning of alignment of its super high accuracy lithography system wafer is:

the method comprises the following steps: the off-field three-dimensional marks 1221 are used as reference points for aligning and positioning chip regions, such as the coordinate positions of three-dimensional protruding (recessed) marks between chip regions or on the edge of a wafer, i.e., the positions of chip region patterns are measured by a probe tip sensor (the coordinate positions of the chip region patterns on the wafer and the three-dimensional protruding (recessed) marks on the wafer and their relative coordinate positions are predetermined and are not changed by the movement of a wafer stage and the deviation of a light beam). The exposed wafer area is then moved out of the projection exposure area by the movement of the wafer stage 100, and the new coordinates of the three-dimensional protruding (recessed) marks in the middle of the wafer area or at the edge of the wafer are measured and compared with the coordinates of the previously exposed wafer area in the projection exposure area to form a coordinate offset difference for the next wafer area to be exposed. The coordinate difference can be used for driving an exposure beam generating device such as a mask plate to perform nano-scale horizontal movement for compensation, can also be used for driving a photon beam/electron beam projection objective lens group to perform nano-scale horizontal movement, can also be used for driving the photon beam/electron beam or a deflection mirror to perform nano-scale horizontal movement, and can also be used for driving a wafer workbench or a piezoelectric wafer workbench which is arranged on the wafer workbench and has smaller step length, so that the alignment error of a wafer area/a writing field can be sufficiently corrected.

Method two the relief pattern formed by radiation induced modification (IIRC) of the photosensitive layer after exposure of the first wafer area as shown in fig. 5A and 5B as position coordinates for alignment of the next wafer area. In the method, the wafer area to be exposed does not have a corresponding three-dimensional mark, namely, the three-dimensional mark is not arranged in the wafer area or around the wafer area, when the needle tip sensing head scans in a certain scanning area, the boundary of the wafer area is determined according to the three-dimensional mark of the three-dimensional pattern formed on the previous wafer area which is already exposed, and then whether the next wafer area to be exposed needs to carry out nanometer displacement fine adjustment and the deviation of adjustment is determined.

The third method comprises the following steps: the method is set by combining the method I and the method II. Considering that the method in a preferred embodiment is to provide three-dimensional marks for each chip area, since there are many chip areas on a wafer, it is necessary to make a lot of bottom alignment marks on the wafer in advance. And the method two adopts the exposure three-dimensional pattern three-dimensional mark of the previous wafer area to position and possibly has the problem of accumulated errors, so the method combines the method one and the method two, the wafer area provided with the corresponding three-dimensional mark and the wafer area not provided with the three-dimensional mark are arranged at intervals, namely the three-dimensional mark corresponding to the wafer area is used as an absolute reference point to realize the exposure overlay alignment of the first wafer area, then the irradiation induced photosensitive layer modification (IIRC) exposed by the wafer area is used as the alignment coordinate of the transverse wafer area, the alignment is transferred to the alignment and exposure of the next wafer area, after the exposure of a plurality of wafer areas is transferred, the three-dimensional mark corresponding to the wafer area is obtained again to be used as the absolute overlay alignment mark, and the absolute exposure alignment of the next wafer area is restarted. Therefore, the alignment precision of all chip areas is ensured, and the setting amount of alignment marks on the upper bottom layer of the wafer is greatly reduced.

The utility model is suitable for a dark ultraviolet and extreme ultraviolet optical lithography machine, solved and can not aim at the measurement with the direct wafer that scribbles the photosensitive layer of photon beam before the exposure, can only fix a position the regional technological problem of wafer through the removal of wafer workstation. The utility model discloses a technical scheme can not produce accumulative nature error. Therefore, the wafer worktable is prevented from returning to the original point each time and moving to the specified position by taking the original point as an absolute reference point, and the working speed is greatly improved. Furthermore, the utility model discloses even still solved the wafer workstation location accuracy, because the drift of the projection objective group of photon beam and mask plate (through various factors such as expend with heat and contract with cold), the photon beam can produce the drift and lead to the technical problem that its final photon beam is complicated with the alignment of wafer.

The above is based on the principle of closed-loop control of the relative position between the wafer and the exposure beam to perform the overlay alignment of the chip area. This alignment mechanism is more accurate than a precise wafer stage. Because the beam drift on the wafer is difficult to compensate for by the wafer stage, even if the wafer stage is temporarily accurately positioned, it is difficult to compensate for by a laser interferometer aligned between the wafer and the beam.

While the present invention has been described in detail with reference to the preferred embodiments thereof, it should be understood that the above description should not be taken as limiting the present invention. Numerous modifications and alterations to the present invention will become apparent to those skilled in the art upon reading the foregoing description. Accordingly, the scope of the invention should be limited only by the attached claims.

Claims

1. A lithographic pattern alignment apparatus, said apparatus being located within a lithographic apparatus body, said apparatus comprising:

2. The lithographic pattern alignment apparatus of claim 1, wherein: the device also comprises a computer control system, wherein the computer control system is used for receiving the three-dimensional mark coordinate measured by the nanometer needle point sensing device and comparing the three-dimensional mark coordinate with the reference coordinate of the three-dimensional mark to obtain the difference value of the two coordinates, and the computer control system is used for transmitting the difference value to the displacement driving device and controlling the exposure beam generating device and/or the wafer worktable to move mutually to compensate the difference value.

3. The lithographic pattern alignment apparatus of claim 2, wherein: the reference coordinates are preset position coordinates of the three-dimensional marks, when the three-dimensional marks are located at the preset positions, the wafer area to be exposed is aligned with the projection exposure area, and the reference coordinates are stored in the computer control system in advance.

4. The lithographic pattern alignment apparatus of claim 2, wherein: the reference coordinate is a coordinate which is measured by the nanometer needle point sensing device before the exposure of the wafer area and corresponds to the scanning area after the distance of the wafer which is theoretically moved for realizing the alignment of the next wafer area to be exposed and the projection exposure area is combined, and the distance of the wafer which is theoretically moved in the transverse direction and the longitudinal direction is stored in the computer control system in advance.

5. The lithographic pattern alignment apparatus of claim 1, wherein: the three-dimensional mark on the photosensitive layer comprises a three-dimensional mark which is correspondingly formed on the photosensitive layer by a bottom layer alignment mark arranged below the photosensitive layer and/or a three-dimensional stereo pattern which is formed by irradiation induced photosensitive layer modification (IIRC) formed by exposure of exposure beams on the surface of the photosensitive layer.

6. The lithographic pattern alignment apparatus of claim 5, wherein: the three-dimensional mark correspondingly formed on the photosensitive layer by the bottom layer alignment mark is positioned in the wafer area or the off-field area between the adjacent wafer areas.

7. The lithographic pattern alignment apparatus of any of claims 5 or 6, wherein: the bottom layer alignment mark comprises a mark manufactured on the surface of the wafer substrate before the first exposure of the wafer and/or a mark arranged below the photosensitive layer in a subsequent exposure process.

8. The lithographic pattern alignment apparatus of claim 1, wherein: the height of the three-dimensional mark is greater than the surface roughness of the photosensitive layer.

9. The lithographic pattern alignment apparatus of claim 1, wherein: the coordinates of the three-dimensional mark comprise transverse position coordinates, longitudinal position coordinates and circumferential position coordinates of the wafer.

10. The lithographic pattern alignment apparatus of claim 1, wherein: two or more three-dimensional marks are arranged on the photosensitive layer.

11. The lithographic pattern alignment apparatus of claim 1, wherein: the three-dimensional mark has certain graphic features, wherein the graphic features comprise at least one dot-shaped feature, and the dot-shaped feature and the upper surface of the photosensitive layer are located in different horizontal planes.

12. The lithographic pattern alignment apparatus of claim 11, wherein: the pattern features further include ridge features connected to the dot features, the ridge features and the upper surface of the photosensitive layer not being completely in the same plane.

13. The lithographic pattern alignment apparatus of claim 1, wherein: the three-dimensional mark is a three-dimensional structure protruding or recessed from the upper surface of the photosensitive layer.

14. The lithographic pattern alignment device of claim 13, wherein: the three-dimensional structure is at least one of a conical structure, a polygonal prismatic structure and a pyramidal structure.

15. The lithographic pattern alignment apparatus of claim 1, wherein: at least one three-dimensional mark is correspondingly arranged in each wafer area, the three-dimensional mark is positioned in the wafer area or an off-site area around the wafer area, and the reference coordinates of the three-dimensional mark are stored in a computer control system in advance.

16. The lithographic pattern alignment apparatus of claim 1, wherein: and the wafer area is not provided with a corresponding three-dimensional mark, and the alignment of the wafer area and the projection exposure area is realized according to the three-dimensional mark of the three-dimensional pattern in the previous wafer area which is subjected to exposure and is measured by the needle tip sensing head.

17. The lithographic pattern alignment apparatus of claim 16, wherein: the wafer area without the corresponding three-dimensional mark is arranged at a distance from the wafer area with the corresponding three-dimensional mark.

18. The lithographic pattern alignment apparatus of claim 1, wherein: the exposure beam generating device is provided with a positioning mark generating device, the positioning mark generating device forms a three-dimensional positioning mark on the periphery of the wafer area while exposing the wafer area, and the needle tip sensing head carries out positioning calibration on the position of the wafer area to be exposed according to the three-dimensional positioning mark.

19. The lithographic pattern alignment apparatus of claim 1, wherein: the height of the three-dimensional mark is less than or equal to 50 micrometers.

20. The lithographic pattern alignment apparatus of claim 1, wherein: the needle tip sensing head is one or a combination of an active atomic force needle tip sensing head, a laser reflection type atomic force needle tip sensing head, a tunnel electronic probe sensing head or a nano-scale surface work function measurement sensing head.

21. The lithographic pattern alignment apparatus of claim 1, wherein: the needle sensing head is used for measuring the surface structure of the wafer in the atmosphere or vacuum environment, or the needle sensing head is immersed in liquid in the immersion environment for measuring the surface structure of the wafer.

22. The lithographic pattern alignment apparatus of claim 21, wherein: for immersion lithography, the three-dimensional marks are three-dimensional marks in an immersion environment, or three-dimensional marks of a wafer region corresponding to an adjacent wafer region in an immersion environment outside of the exposure beam.

23. The lithographic pattern alignment apparatus of claim 1, wherein: the surface structure data of the three-dimensional mark measured by the needle tip sensing head is the mathematical convolution of the surface structure of the three-dimensional mark and the needle tip structure of the needle tip sensing head, and the needle tip sensing head carries out the measurement and calibration of the needle tip structure before the three-dimensional mark is measured.

24. The lithographic pattern alignment apparatus of claim 1, wherein: the nanometer needle point sensing device further comprises a micro-cantilever, one end of the micro-cantilever is fixed, and the other end of the micro-cantilever is provided with the needle point sensing head.

25. The lithographic pattern alignment device of claim 24, wherein: the nanometer needle point sensing device comprises one or more needle point sensing heads, and the needle point sensing heads are fixed on one side or two sides of the exposure beam generation device through the micro-cantilever.

26. The lithographic pattern alignment device of claim 25, wherein: the exposure beam generating device comprises a projection objective lens group arranged above the wafer, and the one or more needle tip sensing heads are fixed on one side or two sides of the projection objective lens group through micro-cantilevers.

27. The lithographic pattern alignment device of claim 24, wherein: the wafer workbench comprises a moving part and a fixing part, and the needle tip sensing head is connected with the fixing part through the micro cantilever.

28. The lithographic pattern alignment device of claim 27, wherein: the nanometer needle point sensing device comprises two or more needle point sensing heads, wherein one or more needle point sensing heads are fixed on a fixed part of the wafer workbench, one or more needle point sensing heads are fixed on the side edge of the exposure beam generating device, and the relative distance between the needle point sensing heads is fixed.

29. The lithographic pattern alignment apparatus of claim 1, wherein: the nanometer needle point sensing device comprises two or more needle point sensing heads, a plurality of the needle point sensing heads are fixed on one side or two sides of the exposure beam generating device through a connecting piece, and the distances among the plurality of the needle point sensing heads are relatively fixed.

30. The lithographic pattern alignment apparatus of claim 1, wherein: the nanometer needle point sensing device comprises three or more needle point sensing heads, the needle point sensing heads are fixed on a fixed part of the wafer workbench through connecting pieces and/or are fixed on the exposure beam generating device through connecting pieces, and the needle point sensing heads are positioned on different straight lines to determine whether the wafer and the exposure beam are vertical or not.

31. The lithographic pattern alignment device of claim 30, wherein: and each needle point sensing head tests the distance from the surface of the wafer or the surface of the photosensitive layer corresponding to the position of the needle point sensing head to the exposure beam generating device, judges whether the wafer is vertical to the exposure beam or not according to the same measured distance, and drives the wafer workbench to adjust the wafer to be vertical to the exposure beam through a computer control system.

32. The lithographic pattern alignment apparatus of any of claims 26-29, wherein: the nanometer needle point sensing device comprises a plurality of needle point sensing heads fixed through connecting pieces, and the plurality of needle point sensing heads are transversely arranged in a row according to the distribution of the wafer area to form a transverse needle point sensing head array.

33. The lithographic pattern alignment device of claim 32, wherein: one end of the transverse needle tip sensing head array is provided with at least one needle tip sensing head which is longitudinally distributed to form an L-shaped needle tip sensing head array.

34. The lithographic pattern alignment device of claim 32, wherein: the two ends of the transverse needle point sensing head array are respectively provided with longitudinally distributed needle point sensing heads to form a U-shaped needle point sensing head array.

35. The lithographic pattern alignment device of claim 32, wherein: the distance between two adjacent needle tip sensing heads is larger than or equal to the transverse width of one wafer area.

36. The lithographic pattern alignment apparatus of claim 1, wherein: the displacement driving device comprises a wafer area switching driving device and a nanometer displacement driving device.

37. The lithographic pattern alignment device of claim 36, wherein: the wafer area switching driving device is connected with the moving part of the wafer workbench and used for driving the wafer areas to be exposed to be sequentially exposed below the projection exposure area.

38. The lithographic pattern alignment apparatus of claim 37, wherein: the moving part of the wafer workbench further comprises a precision moving device, and the nanometer displacement driving device is the precision moving device.

39. The lithographic pattern alignment device of claim 36, wherein: and the nano displacement driving device is connected with the exposure beam generating device and/or the precision moving device of the wafer workbench and is used for controlling the exposure beam generating device and/or the wafer workbench to move transversely and/or longitudinally and/or circumferentially.

40. The lithographic pattern alignment device of claim 36, wherein: the working principle of the nanometer displacement driving device for driving the exposure beam generating device and/or the precision moving device of the wafer workbench to move is at least one of a piezoelectric principle, a voice coil driving principle or an electromagnetic driving principle.

41. The lithographic pattern alignment apparatus of claim 1, wherein: the exposure beam generated by the exposure beam generating device is at least one of a light beam, an electron beam, an ion beam or an atom beam.

42. The lithographic pattern alignment device of claim 36, wherein: the exposure beam generating device is a light beam generating device, the light beam generating device comprises a light source, an optical gate, a light beam deflection sheet/reflector, a mask plate and a projection objective lens group, the nanometer displacement driving device is connected with the light beam deflection sheet/reflector, and at least one of the mask plate and the projection objective lens group is connected so as to adjust the position of a projection exposure area of the light beam generating device.

43. The lithographic pattern alignment device of claim 33, wherein: the at least one needle tip sensing head is fixed on at least one side of the projection objective lens group.

44. The lithographic pattern alignment device of claim 41, wherein: the exposure beam is a parallel beam or a gaussian beam.

45. The lithographic pattern alignment apparatus of claim 42, wherein: the beam shaping and focusing system may be composed of optical lenses or optical mirrors.

46. The lithographic pattern alignment apparatus of claim 1, wherein: the wafer may comprise a complete wafer, a partial wafer, or a non-wafer substance requiring a photolithographic exposure process.

47. A stepping photoetching machine is used for realizing repeated exposure to a plurality of chip areas in a wafer, and is characterized in that: the lithography machine is provided with a lithographic pattern alignment apparatus according to any of claims 1 to 46.