Sub-nanometer high-precision photolithography write field stitching method, photolithography system used, wafer and electron beam drift measurement method

Abstract

A sub-nanometer high-precision photolithography write field stitching method, the photolithography system used, the wafer, and the method for measuring electron beam drift are disclosed. A photosensitive adhesive layer is coated on the surface of the wafer to be lithographically aligned. After exposure, the exposed pattern of the photosensitive adhesive layer produces tiny uneven structures. These uneven structures can be identified using nano-contact sensors and used as in-situ alignment coordinate markers. By comparing the position coordinates of the write field before and after exposure, and before and after wafer movement, the stitching deviation is calculated. High-precision photolithography stitching of the wafer is achieved using negative feedback control. This overcomes the shortcomings of existing non-in-situ, far-from-the-write-field, blind open-loop photolithography stitching technologies, which suffer from poor stitching accuracy due to the influence of the mechanical movement accuracy of the wafer stage and long-term electron beam drift. It also breaks through the bottleneck of existing technologies that heavily rely on the numerical control accuracy of the wafer stage in the photolithography system. This provides a novel photolithography write field stitching method, electron beam drift measurement method, photolithography system, and wafer with sub-nanometer precision.

Description

Technical Field

[0001] This invention relates to photolithography technology used in the production of integrated circuits, optoelectronic devices, etc., specifically to a precise alignment technique for positioning electron beam (here, electron beam refers to electron beam, photon beam, ion beam, or atomic beam) photolithography in the lateral and / or longitudinal stitching of patterns, the accompanying photolithography machine system, and the wafer. In particular, it relates to a sub-nanometer-level high-precision photolithography write field stitching method, photolithography machine system, and pre-processed wafer based on spatial in-situ closed-loop control technology for write field stitching in an electron beam lithography system. Background Technology

[0002] The development of microelectronics and optoelectronics has spurred the rapid growth of integrated circuit chips, integrated optics, and quantum computing industries. These industries have become the foundation for core components and chips in modern computers, displays, and even the entire information industry. Currently, the technology nodes of the modern chip industry have reached 5 nanometers or even smaller.

[0003] The manufacture of micro and nanodevices such as chips is inseparable from photolithography technology. Photolithography technologies include electron beam lithography, conventional optical lithography, EUV (Extreme Ultraviolet) lithography, ion beam lithography, and scanning probe lithography. These key photolithography technologies are essential for creating intricate lithographic patterns and a wide range of micro and nanodevice structures, including integrated circuit chips and optoelectronic integrated chips.

[0004] In today's era, multi-mask patterning technology, while significantly increasing the integration density of integrated circuits in the semiconductor industry, has also increased the complexity of chip manufacturing. A 28-nanometer chip requires 40 to 50 masks (e.g., 20 mm in length and width). Based on this, a 14-nanometer or 10-nanometer chip requires 60 masks (e.g., 20 mm in length and width), while a 7-nanometer chip or even smaller requires as many as 80 to 85 masks, and a 5-nanometer chip requires 100 masks and 120 lithography steps! Solving the problem of stitching alignment accuracy in lithography and ensuring the consistency of alignment between these masks has always been a major challenge in template fabrication for large wafer and chip sizes. This necessitates more precise (even smaller than 1 nanometer) chip lithography manufacturing processes, for which no such high-precision lithography technology currently exists worldwide.

[0005] Electron beam lithography (EBL) systems in the current technology are a nanoscale lithography technology widely used in scientific research, sample preparation, and industrial template fabrication and production. This EBL system uses only a limited number of write fields for exposure. Therefore, large patterns must be divided into many adjacent write fields, and each field is exposed individually by moving the wafer stage. Ideally, these adjacent write fields should be perfectly aligned and stitched together. However, in reality, due to mechanical movement and electron beam drift, errors are inevitable, and these errors are significant and difficult to overcome. This error is called stitching error.

[0006] The term "wafer" here refers not only to wafers, but also to some wafers and non-wafer samples.

[0007] Before photolithography, a smooth photosensitive adhesive layer is coated on the wafer, with no other structures on its surface. Scanning the photosensitive adhesive layer with an electron beam based on a pre-defined pattern causes a chemical reaction. The exposed pattern on the photosensitive adhesive layer is either preserved or removed through chemical development, thus transferring the electron beam-exposed pattern to the photosensitive adhesive layer and ultimately onto the wafer through etching. Due to the lack of in-situ feedback (where in-situ refers to the coordinate position within the write field of the electron beam scan), traditional electron beam lithography is an open-loop controlled "blind operation." Once the photosensitive adhesive layer is coated, the electron beam can no longer scan the wafer surface, as scanning implies exposure of the photosensitive adhesive layer. The exposed position can only be observed after the photosensitive adhesive layer has developed and is in a different location. This makes any improvements to the lithography process too late and irreversible. The stitching quality of the write field pattern cannot be measured before exposure and fed back to the stage for further alignment corrections. Furthermore, the mechanical movements of the wafer stage are too slow to adapt to electron beam drift and cannot overcome the resulting errors.

[0008] Therefore, finding a way to measure and calibrate alignment errors in situ throughout the entire photolithography exposure process for the desired pattern is the way to further improve the accuracy of photolithography technology. However, no one has found such a method yet, nor is there a photolithography system for implementing it.

[0009] To facilitate a more thorough disclosure and easier understanding of the technical problems that this invention aims to solve, before describing the technical solutions and specific embodiments of this invention, the following will introduce technical terms and operating principles that will help to fully explain and facilitate public understanding.

[0010] The electron beam described in this invention can be a Gaussian beam or a deformed beam. Unless otherwise specified, the electron beam referred to below is a Gaussian electron beam; however, a deformed beam can also be used if the beam spot is small.

[0011] Figure 1 illustrates the principle of Gaussian beam exposure. A Gaussian electron beam is focused onto the surface of the photosensitive adhesive layer and exposed. The coordinates of the electron beam refer to the coordinates of the position on the photosensitive adhesive layer surface where the electron beam is aimed. The coordinates of the electron beam are represented by the position of the electron beam exposed on the surface of the photosensitive adhesive layer.

[0012] To record accurate electron beam coordinates, several special coordinate systems are defined here: the coordinates on the photosensitive adhesive layer immediately after electron beam exposure are CPJE, and the coordinates on the area where the electron beam has been aimed but not yet exposed are CPTE. Both coordinate systems share a common characteristic: the electron beam coordinates are "pinned" to the coordinates of the photosensitive adhesive layer surface.

[0013] In electron beam lithography systems, errors caused by the movement of the wafer stage can be adjusted and compensated for by the deflection of the electron beam. The method for locating these errors is through alignment marks on the wafer.

[0014] In electron beam lithography, the lithographic pattern is transferred to a photoresist layer through exposure, and then transferred to the wafer through an etching process. It's important to note that in existing technologies, the photoresist layer coated on the wafer flattens the wafer surface without any patterned structure. This photoresist layer forms the upper surface, which, due to its photosensitive nature, prevents the electron beam from creating a surface image before exposure (i.e., during exposure), and further prevents it from penetrating the photoresist layer to obtain the pattern on the wafer beneath. Furthermore, the lithography system requires precise alignment with the pattern during exposure. Although this alignment accuracy is limited by errors inherent to the system itself and environmental factors, the fundamental problem is the open-loop control issue in most lithography systems: the position of the electron beam on the wafer cannot be observed and tracked before and during exposure.

[0015] Traditional electron beam lithography (EBL) alignment has inherent flaws. The alignment marks (Figure 2) are far from the write field, meaning they can only be indirectly aligned during the EBL write field stitching process through wafer stage movement, rather than precise, direct in-situ alignment within the write field. This leads to alignment errors. Precise in-situ alignment refers to the alignment of the electron beam with the alignment marks within the write field. Given that the repeatability of the electron beam within the exposure area's write field is generally less than 1 nanometer, the coordinate position of the electron beam deflected within any exposure area's write field is precisely within this range. Therefore, the concept of in-situ alignment can be extended to the alignment of the electron beam with any alignment mark within the exposure area's write field; this can be considered in-situ alignment.

[0016] For the alignment between write fields, specialized alignment marks are required to ensure that the coordinates of the wafer pattern and the electron beam coincide. Since the electron beam cannot be imaged by an electron microscope on the surface with the photosensitive adhesive layer applied, it is impossible to locate the wafer pattern coordinates corresponding to the photosensitive adhesive layer before exposure. Therefore, specific coordinate positions outside the write field must be selected on the wafer to allow the electron beam to determine and align the wafer pattern. The electron microscope moves with the wafer stage from this specific coordinate position outside the write field to the exposure point of the electron beam. The positional errors caused by mechanical movement precision and electron drift significantly limit the accuracy of current wafer write field stitching.

[0017] Large pattern electron beam lithography

[0018] Large-area patterning lithography transfers electron beam patterning designs to wafers, enabling these patterns to meet a wide range of application requirements. These applications represent a huge market. These applications include optical gratings, large-area Fresnel lenses, extreme ultraviolet lithography masks for integrated circuits, distributed feedback lasers, semiconductor laser arrays, photonic crystals, and large-scale memory. The (length) dimensions of the patterns can range from 10 mm to over 300 mm.

[0019] Because the write field is very small, it cannot be completed in one photolithography session for large-area lithography. Therefore, it is necessary to stitch together many electron beam write fields. The stitching error accumulates and forms a serious systematic error, so the accuracy of the stitching error is very high.

[0020] Alignment Marks

[0021] Traditional electron beam lithography systems can only write (expose) patterns within a limited write field without causing distortion of the written pattern. The size of this write field is typically between 100 micrometers x 100 micrometers and 1 millimeter x 1 millimeter. This size is far too small for many applications requiring patterns ranging from 20 millimeters x 20 millimeters to 200 millimeters x 200 millimeters. Larger patterns can only be created by moving the wafer stage and stitching these small write fields together one by one. This leads to a significant accumulation of alignment and stitching errors between a particular write field pattern and its neighboring patterns.

[0022] Since the entire wafer is covered by a photosensitive adhesive layer, the entire wafer is a "useful" area. Therefore, electron beam lithography alignment typically requires using locations outside the write field, or even outside the entire wafer—that is, the wafer edge—as alignment coordinates. In particular, alignment coordinates are selected at the wafer edge, meaning they are set in "useless" areas far from the write field. The reason these alignment coordinates, far from the write field, are currently accepted in the industry is precisely because they are not located in the wafer area requiring pattern exposure. Therefore, they can be used as alignment coordinate marks (hereinafter referred to as alignment marks) by electron beam exposure and can be repeatedly "observed" by the electron beam of an electron microscope, i.e., exposed.

[0023] These alignment coordinate marks are aligned and connected by moving the wafer stage. The control precision of the wafer stage movement, in a sense, determines the accuracy of the write field stitching error. High-precision write field stitching requires the use of an expensive, high-precision laser stage. This is because the main positioning accuracy deviations come from the positioning error of the wafer stage in the direction of movement, the incidental changes in other wafer coordinate directions caused by this movement, and the electron beam drift caused by the long time required for these movements.

[0024] Figure 3 Alignment marks 13, which are existing "off-field marks" (alignment marks 12 located at the edge of the wafer and alignment marks 14 located between write fields) and "in-field marks" (IA marks) that can be scanned by an electron beam and are not currently used by anyone, are also shown.

[0025] Alignment mark 12 is set at the edge of the wafer, away from the write field.

[0026] Alignment mark 14 is set between write fields (if there is space between write fields). In reality, there are many situations where space between write fields is not allowed. Rasteres or Fresnel lenses are examples. The grating lines cannot be broken in the middle to leave space.

[0027] Both alignment mark 12 and alignment mark 14 require movement of the wafer stage to place the new write field under the electron beam irradiation aiming. Stage movement not only causes alignment errors but also leads to longer alignment time, resulting in electron beam drift due to various unstable factors (such as temperature drift, humidity drift, etc., see Figure 7).

[0028] If alignment marks are placed within the write field that the electron beam can scan, alignment here does not require movement of the wafer stage. Using this type of mark can avoid prolonged alignment adjustments of the electron beam, thus reducing electron beam drift. We will tentatively call this type of alignment mark "in-field mark" (IA mark). However, according to existing technology, the in-field mark 13 occupies a large area, and so far no one in the industry believes that it can be used to completely solve the problem of write field stitching accuracy.

[0029] If the field marker 13 could be made as small as a few nanometers to a few hundred nanometers, it would be very practical due to its small area. However, so far, it is difficult to think of a solution to this problem, and there is no corresponding technology to enable the field marker to be made as small as a few nanometers to a few hundred nanometers, and there is a means to identify it.

[0030] If this tiny in-field mark 13 is small enough and very close (e.g., within a few nanometers to tens of nanometers) to the coordinates of the photosensitive adhesive layer surface that the electron beam is aiming at, this in-field coordinate becomes the in-situ alignment coordinate mark (ISA mark) as described in this invention.

[0031] If the field mark 13 is exactly under the electron beam coordinates, that is, the coordinates of the exposure pattern on the photosensitive adhesive layer / wafer exactly overlap with the electron beam exposure coordinates (target coordinates), this field coordinate is called the "overlap alignment coordinate" mark (OA mark) as described in this invention.

[0032] Because the electron beam has a very high repetition accuracy in the writing field (generally within 1 nanometer), the marks in the writing field can be approximated as in-situ aligned marks.

[0033] 3D alignment mark

[0034] Electron beam irradiation is used to sense and image alignment marks. These alignment marks are generally planar, i.e., two-dimensional. However, three-dimensional marks on the photosensitive adhesive layer and wafer surface can also be used as alignment marks. For example, by measuring the peak position or concave position of the three-dimensional mark, a precise alignment coordinate can be determined. The unevenness of the wafer surface generally causes the surface of the photosensitive adhesive layer covering it to form an uneven structure, so the unevenness and position of the surface can be measured.

[0035] Electron beam induced modification of photosensitive adhesive layer

[0036] Electron beam induced change (EIRC) refers to changes in the chemical and / or physical properties of a photosensitive adhesive layer at the site of electron beam irradiation. Chemical changes include electron beam-induced chemical reactions on the surface of the photosensitive adhesive layer, causing the irradiated portion to change from an insoluble state to one that dissolves during development (positive adhesive), or from a dissolved state to an insoluble state through exposure (negative adhesive). Physical changes in the photosensitive adhesive layer caused by electron beam exposure include minute changes in the surface geometry of the photosensitive adhesive layer, such as expansion or contraction at the sub-nanometer or nanometer scale, forming uneven structures (see Figure 2). These changes in the uneven structure of the photosensitive adhesive layer occur when electron beam exposure transfers electron beam pattern information onto the photosensitive adhesive layer.

[0037] One method for generating three-dimensional markings involves electron beam-induced modification of the photosensitive adhesive layer. This modification, caused by electron beam exposure, results in physical changes to the photosensitive adhesive layer, including minute geometrical changes on its surface, such as expansion or contraction at the sub-nanometer or nanometer scale, forming an uneven structure. Figure 2a , 2b As shown, exposure causes the photosensitive adhesive layer pattern to expand or shrink in height, forming a three-dimensional geometric height pattern. This deformation can be detected at the sub-nanometer scale by a nano-contact sensor (a highly sensitive sensor).

[0038] Another method for generating 3D markings is to pre-define a 3D structure on the wafer, such as a 3D protrusion: a micro-cone, a micro-pyramid, or a micro-contact. Their diameter scale ranges from a few nanometers to tens of nanometers. These microstructures can be achieved using electron beam lithography or electron beam-induced deposition techniques. (See attached image.) Figure 4 The three-dimensional marks 18 and 19 in the image are such pre-set three-dimensional protrusions, which we will also refer to below as wafer protrusion alignment marks (HAMW marks).

[0039] On the 3D raised alignment mark 19 coated with a thin layer of photosensitive adhesive, for example, between 10 nanometers and 300 nanometers thick, the surface layer of the photosensitive adhesive layer on the wafer 3D raised alignment mark 19 (HAMW) also becomes a 3D structure. The height of this 3D structure can correspondingly range from a few nanometers to tens of nanometers, accurately indicating its position on the photosensitive adhesive layer surface as the 3D alignment mark 18 (HAMR). This position is completely equivalent in the vertical direction to the position of the wafer 3D alignment mark vertically below. In this way, we can accurately determine the lateral coordinates of the wafer pattern, and importantly, these lateral coordinates can be set within the write field. Setting these 3D alignment marks determines the alignment accuracy to the point that alignment does not depend on the accuracy of the wafer stage movement. This allows the use of a stage with low movement positioning accuracy. For example, a stage requiring a positioning accuracy of 1 nanometer can be replaced by a stage with a positioning accuracy of 1000 nanometers, significantly reducing stage costs.

[0040] Lateral Stiching Alignment (LSA) Error

[0041] One of the major challenges of electron beam lithography systems is the significant stitching error between the previous write field and the next adjacent write field (see appendix). Figures 5a-5c To expose large-area patterns, it is necessary to stitch together individual write fields using the movement of the wafer stage to form a large pattern. According to current electron beam lithography technology, the stitching between write fields is achieved through the movement of the wafer stage. The positioning accuracy of the new write fields depends heavily on the positioning accuracy of the stage and the electron beam drift. Generally, extremely high-precision, expensive laser stages with positioning accuracy within several nanometers are used. However, even highly precise laser stages are extremely sensitive to environmental changes (temperature, humidity, etc.), making it difficult to achieve and repeat nanometer-level precision.

[0042] The stitching error between two adjacent write fields is typically + / - 20 nm for a 100 kV electron beam lithography system and + / - 35 nm for a 30 kV electron beam lithography system. A 35 nm write field stitching error translates to a worst-case stitching error of 700 nm, rendering the grating array useless! Such large-area, high-precision applications especially require much smaller stitching errors, such as within the 1 nm range.

[0043] Vertical Alignment (VA) Error

[0044] Vertical alignment refers to aligning the electron beam with the write field 22 (taking the photolithography grating 23 as an example) to be exposed within the exposure area, and aligning it with the corresponding coordinates of the previous write field 22' that has already been exposed and moved out. Figures 6a-6b The difficulty in achieving this lies in the fact that the wafer to be exposed is covered and separated by a thin layer of photosensitive adhesive. The thickness of the photosensitive adhesive layer is typically between 10 nanometers and 500 nanometers. The photosensitive adhesive layer makes the pattern structure on the wafer "invisible" to the electron beam, so that the electron beam cannot align with the pattern on the wafer. Therefore, typically, alignment marks 24 are used, located outside the electron beam write field. Aligning these marks requires the movement of the stage, and in the case of open-loop control of electron beam lithography, these alignments outside the write field are not direct alignments, that is, not in-situ alignments. The movement of the stage introduces an error between the write field 22 before wafer movement and the write field 22' after wafer movement.

[0045] Alignment error within one writing field

[0046] As mentioned above, current electron beam lithography systems require alignment marks outside the write field, even located at the wafer edge. However, these alignment coordinate marks are not directly aligned (i.e., indirectly aligned), are inaccurate, not in-situ, and time-consuming. An improved method is to set alignment marks 13 within the write field. However, a practical problem remains: if alignment marks are set within the write field, they will be covered by layers of photoresist and cannot be "seen" by the electron beam. Therefore, in the prior art, the method of "setting alignment marks within the write field" would not be considered, or even if considered, would not be adopted.

[0047] Characterization of electron beam spot (Figure 7)

[0048] The surface texture of the electron beam photosensitive adhesive layer (electron beam-induced modified EIRC) can also be used to characterize and calibrate the performance of the electron beam.

[0049] a): Measurement of electron beam spot. The uneven shape left by the electron beam on the surface of the photosensitive adhesive layer is precisely the shape of the electron beam spot.

[0050] b): Electron beam drift over time. The exposure unevenness left by the electron beam on the photosensitive adhesive surface shifts over time and can be measured by a contact sensing system. This drift can be used for compensation and correction of the electron beam writing field, but to the knowledge of the art, no one has disclosed a similar idea in the prior art.

[0051] In summary, current photolithography technology suffers from several drawbacks. The presence of an opaque photosensitive adhesive layer 2 on the surface of the wafer 1 to be processed (exposed) necessitates that alignment coordinate marks be placed outside the write field, particularly at the outer edge of the entire wafer (i.e., not in situ), far from the direct alignment point of the electron beam exposure. This results in mechanical errors due to the mechanical displacement of each write field, errors in the stitching of each write field pattern, and exposure errors caused by the long-term drift of the electron beam due to the time-consuming process. Because these system errors are not in situ, employing a "blind" open-loop control system, the error system cannot compensate for or repair these errors. Consequently, the stitching errors in existing technologies are substantial and difficult to overcome. Limited by current electromechanical processing precision, the accuracy of current photolithography systems is difficult to improve further, and they remain expensive. Summary of the Invention

[0052] In order to overcome the shortcomings of the existing technology, the technical task to be accomplished by the present invention is as follows:

[0053] 1. A sub-nanometer high-precision photolithography writing field splicing method is provided, which is not limited to the electromechanical processing precision of existing wafer work stages, and can accurately detect writing field exposure deviation in real time and perform photolithography processing in an automatic closed-loop control splicing correction manner.

[0054] 2. A lithography system for processing wafers using this method is provided;

[0055] 3. A pre-processed wafer for implementing the above method is provided;

[0056] 4. To provide a method for measuring electron beam drift;

[0057] 5. A method for longitudinal stitching of photolithography writing fields with sub-nanometer high precision is provided.

[0058] The objective of this invention is achieved through the following technical solutions:

[0059] I. A sub-nanometer high-precision photolithography write field stitching method, comprising the following steps:

[0060] Step 1: Inside the lithography machine system, set up the stage, electron microscope tube and its electron gun, wafer moving stage, and at least one nano-contact sensor; install a CNC drive device to control the movement of the wafer on the wafer moving stage; before the wafer is placed into the lithography machine system, a photosensitive adhesive layer is coated on the entire wafer. The electron beam scanning range is the exposure area, which is divided into several write fields. Each write field on the photosensitive adhesive layer has a specific in-situ alignment coordinate mark that will be exposed in a predetermined shape after exposure in the exposure area; the write fields are sequentially named the first write field, the second write field, ..., the nth write field;

[0061] Step 2: Place the wafer coated with photosensitive adhesive on the worktable and make the first write field of the wafer fall into the exposure area. Make the electron beam tube of the electron microscope perpendicular to the exposure area and then focus the electron beam on the write field.

[0062] Step 3: Expose a portion of the wafer on the first write field within the exposure area, causing the photosensitive adhesive coated on this portion of the wafer to undergo a chemical reaction, resulting in electron beam-induced changes and producing at least one or a group of concave and convex structures constituting a pattern. The specific shape of the concave and convex structure serves as the feature shape of the pre-set in-situ alignment coordinate marker, and the coordinate values ​​of its feature points within the exposure area serve as the in-situ alignment coordinates.

[0063] Step 4: First, use the nano-contact sensor to measure the surface shape of the concave-convex structure, then identify the alignment coordinate mark by comparing it with the preset specific shape, and then determine and memorize its coordinate value on the worktable.

[0064] Step 5: Prepare for the second write field exposure by moving the worktable to move the wafer horizontally and / or vertically, so that the first write field area that was just exposed is moved out of the exposure area to become write field 22-1´, making room for the second write field of the wafer to enter the exposure area.

[0065] Step 6: Activate the nano-contact sensor to identify the alignment coordinate markers in the first write field that has been removed from the exposure area, determine and memorize the coordinates of the first write field position on the worktable after the movement;

[0066] Step 7: Using the alignment coordinate data within the first write field after the shift as the basis for closed-loop feedback control, calculate the actual coordinate deviation before and after the write field shift, and then determine the coordinate correction value for the entire exposure area in the next electron beam frame:

[0067] Let C1R1´ be the coordinate of the second write field, which is adjacent to the first write field that has been moved out of the exposure area and is about to be exposed after error correction. That is, the coordinates (X... C1R1´ Y C1R1´ This is also the new coordinate system that the second writing field, which will soon be revealed, needs to be seamlessly stitched to the new coordinates of the moved first writing field, namely:

[0068] (X) C2L1´ Y C2L1´ ):X C2L1´ =X C1R1´ Y C2L1´ =Y C1R1´ ;

[0069] The electron beam is now pointing towards the second writing field located within the exposure area before error correction, at coordinates C2L1, i.e., coordinates (X... C2L1 Y C2L1Since this coordinate point needs to be stitched and corrected for exposure by applying a deflection voltage to the electron beam to fit the already moved edge coordinate C1R1´ of the first write field, the relevant coordinate point of the second write field after correction is C2L1´, and the coordinate difference between C2L1´ and C2L1 is:

[0070] ΔX1= X C2L1´ - X C2L1 = X C1R1´ - X C2L1

[0071] ΔY1= Y C2L1´ - Y C2L1 = Y C1R1´ - Y C2L1

[0072] Since the coordinates of the second writing field are unavailable because the stage has not yet moved and exposure has not yet occurred, the overall electron beam drift in the exposure area for both the first and second writing fields is initially ignored. This ensures that the coordinates of the second writing field before exposure and before correction are equivalent to the coordinates of the first writing field during exposure: X C2L1 =X C1L1 Y C2L1 =Y C1L1 This allows the coordinates to be measured using the uneven structure formed on the surface of the photosensitive adhesive layer due to exposure before the stage moves after the first writing field exposure, thus obtaining the coordinate difference that needs to be compensated for when correcting all electron beam coordinate points in the second writing field:

[0073] ΔX1= X C1R1´ - X C1L1

[0074] ΔY1= Y C1R1´ - Y C1L1 ;

[0075] Step 8: Adjust the deflection voltage of the electron beam tube according to the obtained coordinate difference that needs to be compensated for, and correct the electron beam exposure area so that the splicing coordinates of the second write field of the wafer that subsequently enters the exposure area are corrected to the splicing coordinates adjacent to the moved first write field. The corrected splicing coordinates of the second write field are seamlessly connected with the moved first write field.

[0076] Further measures also include the following steps:

[0077] Step 9: Perform electron beam exposure on the wafer portion of the second write field placed in the exposure area after electron beam exposure coordinate correction, so that the photosensitive adhesive coated on the exposed wafer portion undergoes a chemical reaction to reveal the preset alignment coordinate mark in the write field characterized by a specific concave-convex structure.

[0078] Step 10: Activate the nano-contact sensor to identify the above alignment coordinate mark by comparing it with the preset specific shape, determine and memorize the position coordinates of the feature coordinate point in the second writing field after correction on the worktable;

[0079] Step 11: Prepare for the third write field exposure by moving the stage again to move the wafer laterally and / or vertically. This moves both the previously moved first write field and the newly exposed, corrected second write field. The newly exposed, corrected second write field is moved out of the exposure area. As the stage moves, the position coordinates of the previously moved first write field change, becoming the second moved first write field. The position coordinates change from (C1Lx´,C1Rx´) to (C1Lx´´,C1Rx´´). The position coordinates of the corrected second write field, which is moved out of the exposure area, change from (C2Lx´,C2Rx´) to (C2Lx´´,C2Rx´´). This second write field becomes the moved second write field, making room for the subsequent movement of the wafer's third write field into the exposure area.

[0080] Step 12: Reactivate the nano-contact sensor to identify the alignment coordinate markers in the second field of the above-mentioned removed exposure area, determine and memorize their position coordinates on the worktable (C2L1´´; C2L2´´; C2L3´´; C2R1´´; C2R2´´; C2R3´´).

[0081] Step 13: Using the alignment coordinate data within the second write field after the movement as the basis for closed-loop feedback control, calculate the deviation of the actual coordinates before and after the movement, and then determine the correction values ​​ΔX2 and ΔY2 for the write field of the next electron beam exposure area:

[0082] Let the coordinates of the third write field, which is adjacent to the second write field after it has been moved out of the exposure area and is about to be exposed, be C2R1´´, i.e., coordinates (X... C2R1´´ Y C2R1´´ This is also the calibration coordinate that the third writing field, which will soon be revealed, needs to be seamlessly stitched into the moved second writing field, namely:

[0083] (X) C3L1´´ Y C3L1´´ ):X C3L1´´ =X C2R1´´ Y C3L1´´ =Y C2 R1´´ ;

[0084] The electron beam is currently pointing towards the third write field located within the exposure area at coordinates C3L1, i.e., coordinates (X... C3L1 Y C3L1The coordinate difference between this point and the already moved second write field to be stitched and exposed is C2 R1´´. This coordinate point is to be stitched and exposed along the edge of the already moved second write field by applying a deflection voltage to the electron beam. The relevant coordinate point of the corrected third write field is C3 L1´´. The coordinate difference between C3 L1´´ and C3 L1´ is:

[0085] ΔX2= X C3L1´´ - X C3L1´ = X C2R1´´ - X C3L1´

[0086] ΔY2= Y C3L1´´ - Y C3L1´ = Y C2R1´´ - Y C3L1´ ;

[0087] The overall electron beam drift in the exposure area for both the second and third writing fields is neglected, ensuring that the coordinates of the third writing field before exposure coordinate correction are identical to those of the second writing field during exposure: X C3L1´ =X C2L1´ Y C3L1´ =Y C2L1´ This allows the coordinates to be measured using the uneven structure formed on the surface of the photosensitive adhesive layer due to exposure before the stage moves after the second write field exposure, thus obtaining the coordinate difference that needs to be compensated for for electron beam coordinate correction of all write field exposure points:

[0088] ΔX2= X C2R1´´ - X C2L1´

[0089] ΔY2= Y C2R1´´ - Y C2L1´ ;

[0090] Step 14: Adjust the deflection voltage of the electron beam tube according to the obtained correction value, and correct the electron beam exposure area so that the coordinates of all exposure points in the third write field of the subsequent wafer are consistent with the splicing coordinates of the moved second write field and seamlessly connected.

[0091] Step 15: Repeat the process to complete the exposure, movement, and stitching of the entire write field area of ​​the wafer.

[0092] To elaborate further:

[0093] The electron beam can also be an ion beam, a photon beam, or an atomic beam.

[0094] The nano-contact sensor is one or more of an atomic force tip sensor or a nanoscale surface work function measurement sensor, or a combination thereof.

[0095] The wafer includes a complete wafer, a partial wafer, or non-wafer material that requires photolithography write field splicing.

[0096] The in-situ alignment coordinate identifier is a planar structural graphic identifier.

[0097] The planar structural graphic identifier has 1, 2, 3, 4, 5, 6 or more on a plane.

[0098] The planar structural graphic identifier includes a graphic identifier formed by minute geometrical changes on the surface of the photoresist layer induced by an electron beam.

[0099] The in-situ alignment coordinate marker is a three-dimensional shape marker.

[0100] The three-dimensional shape identifier is pyramidal or conical, and there are 1, 2, 3, 4, 5, 6 or more of these identifiers on a plane.

[0101] The nano-contact sensors are provided in units of 1, 2, 3, 4 or more, distributed around the exposure area.

[0102] The nano-contact sensor is equipped with a lever-type sensing arm, on which one or more needle-tip sensing contacts are arranged in a row.

[0103] The electron beam is a Gaussian beam.

[0104] The electron beam is a deformed beam.

[0105] II. A sub-nanometer high-precision write field stitching lithography system based on the above-mentioned sub-nanometer high-precision write field stitching method includes a stationary machine body and a stage inside the machine body. An electron microscope, at least one nano-contact sensor, and a wafer moving stage are provided above the stage. The electron microscope is equipped with an electron beam tube, which faces the exposure area of ​​the wafer on the wafer moving stage. The exposure area is divided into several write fields. The wafer moving stage is equipped with a CNC drive device for dragging its forward, backward, and / or left, right, and / or up, down movement and angle changes. The nano-contact sensor is equipped with a sensing contact, which is located above the wafer moving stage and to the side of the electron beam tube, so that the sensing contact of the nano-contact sensor can sense the in-situ alignment coordinate mark with a predetermined shape pre-placed under the photosensitive adhesive layer within the write field.

[0106] The aforementioned sub-nanometer high-precision write field stitching lithography system also includes a control computer connected to a pattern generator, an electron beam control system, and a CNC drive device for the wafer stage. The nano-contact sensor collects the in-situ alignment coordinate marking signal and / or electron beam drift signal on the wafer under test and sends it to the pattern generator under the control of the control computer. The pattern generator, under the control of the control computer, sends the processed and corrected electron beam scanning control signal to the electron beam control system. The electron beam control system controls the shutter of the focusing system on the electron beam tube and the deflection coil that controls the electron beam deflection.

[0107] Other technical solutions that can be considered in greater depth include:

[0108] The electron beam tube is also equipped with a secondary electron imaging signal acquisition device, which feeds back the acquired secondary image after electron beam scanning to the control computer via the electron beam control system.

[0109] The nano-contact sensor is one or more of an atomic force tip sensor or a nanoscale surface work function measurement sensor, or a combination thereof.

[0110] The nano-contact sensor is equipped with a lever-type sensing arm, and the sensing arm is equipped with a needle-tip sensing contact.

[0111] Each of the aforementioned contact arms is provided with one or more needle-tip sensing contacts.

[0112] Each of the aforementioned contact arms is provided with at least one row of needle tip sensing contacts, and each row is provided with more than one number of needle tip sensing contacts.

[0113] The nano-contact sensors are arranged in two rows, with four sensors in each row, and the two rows are arranged on both sides of the electron beam tube.

[0114] 3. The pre-processed wafer used in the above-mentioned sub-nanometer high-precision photolithography write field splicing method, wherein the wafer is coated with a photosensitive adhesive layer to be exposed, characterized in that the write field area on the photosensitive adhesive layer of the wafer is provided with an in-situ alignment coordinate mark of a specific shape composed of concave and / or convex parts for contact recognition by the sensing contact of the nano-contact sensor.

[0115] The in-situ alignment coordinate identifier is a planar structural graphic identifier.

[0116] The planar structural graphic identifier has 1, 2, 3, 4, 5, 6 or more on a plane.

[0117] The planar structure graphic identifier is a graphic identifier formed by minute geometrical changes on the surface of the photoresist layer induced by an electron beam.

[0118] The in-situ alignment coordinate marker is a three-dimensional shape marker.

[0119] The three-dimensional shape identifiers are provided in 1, 2, 3, 4, 5, 6 or more on a plane.

[0120] The wafer includes a complete wafer, a partial wafer, or non-wafer material that requires photolithography write field splicing.

[0121] IV. A sub-nanometer high-precision photolithography write field longitudinal stitching method based on any of the aforementioned sub-nanometer high-precision photolithography write field stitching methods, comprising the following steps: Inside the photolithography system, a stage, an electron microscope tube and its electron gun, a wafer moving stage, and a nano-contact sensor are set up; the electron microscope is equipped with an electron beam tube, which faces the exposure area of ​​the wafer on the wafer moving stage, the exposure area being divided into several write fields; the wafer moving stage is equipped with a CNC drive device for dragging its forward and backward and / or left, right and / or up and down movement and angle changes; the nano-contact sensor is equipped with a sensing contact located above the wafer moving stage, enabling the sensing contact of the nano-contact sensor to contact and sense the photosensitive adhesive layer and its pre-set in-situ alignment coordinate markers with a predetermined shape within the write field; the in-situ alignment is pre-set on the wafer to be photolithographically processed. Coordinate markers are used to make a convex three-dimensional alignment mark on the wafer. Then, a photosensitive adhesive layer is coated on it so that a corresponding in-situ alignment coordinate mark (44) is also generated on the photosensitive adhesive layer at the position of the convex three-dimensional alignment mark on the wafer. That is, a convex three-dimensional alignment mark on the photosensitive adhesive layer. Then, the wafer with the three-dimensional alignment mark is moved to the write field area that can be exposed by the electron beam through the wafer stage. The electron beam is aligned with the position of the three-dimensional alignment mark on the photosensitive adhesive layer to perform point exposure. A three-dimensional mark with actual deviation is generated outside the exposure point of the photosensitive adhesive layer. Then, the sensing contact of the nano-contact sensor is used to contact and measure the actual coordinate values ​​of the three-dimensional alignment mark on the photosensitive adhesive layer and the three-dimensional mark with deviation, and then calculate the correction value of the write field exposure area. In this way, the electron gun is controlled to achieve precise longitudinal alignment and exposure, and precise longitudinal splicing is achieved.

[0122] The method further includes the following steps: based on the coordinate values ​​and drift amount of the recorded electron beam drift trajectory over time, calculate the exposure coordinate values ​​and correction compensation difference caused by the drift of the electron beam over time during the start and end interval periods, and obtain the correction coordinates for the next writing field exposure.

[0123] V. Subnanometer-level high-precision photolithography write field longitudinal stitching method based on any of the above-mentioned subnanometer-level high-precision photolithography write field stitching methods. The subnanometer-level high-precision photolithography write field longitudinal stitching method includes the following steps: Inside the photolithography system, a stage, an electron microscope tube and its electron gun, a wafer moving stage, and a nano-contact sensor are set up; the electron microscope is equipped with an electron beam tube, which faces the exposure area of ​​the wafer on the wafer moving stage, and the exposure area is divided into several write fields; the wafer moving stage is equipped with a CNC drive device for dragging its forward and backward and / or left, right and / or up and down movement and angle changes; the nano-contact sensor is equipped with a sensing contact, which is located above the wafer moving stage, so that the sensing contact of the nano-contact sensor can contact and sense the photosensitive adhesive layer and its pre-set in-situ alignment coordinate markers with a predetermined shape within the write field; the area to be photolithographically processed... First, in-situ alignment coordinate marks are pre-set on the wafer, forming a raised three-dimensional alignment mark. Then, a photosensitive adhesive layer is coated on it, so that corresponding in-situ alignment coordinate marks are also generated on the photosensitive adhesive layer at the positions of the raised three-dimensional alignment marks, i.e., raised three-dimensional alignment marks on the photosensitive adhesive layer. Then, the wafer with the three-dimensional alignment marks is moved by the wafer stage to the write field area that can be exposed by the electron beam. The electron beam is aimed at the position of the three-dimensional alignment mark on the photosensitive adhesive layer to perform point exposure, generating a three-dimensional mark with actual deviation outside the exposure point of the photosensitive adhesive layer. Then, the sensing contact of the nano-contact sensor is used to contact and measure the actual coordinate values ​​of the three-dimensional alignment mark on the photosensitive adhesive layer and the deviated three-dimensional mark, and then calculate the correction value of the write field exposure area, thereby controlling the electron gun to achieve precise longitudinal alignment and exposure, and achieving precise longitudinal stitching.

[0124] The nano-contact sensor is one or a combination of two of the following: an atomic force tip sensor or a nanoscale surface work function measurement sensor.

[0125] After the lithography system of the present invention exposes the wafer in the write field area of ​​the exposure zone with an electron beam, the wafer in the write field area will reveal in-situ alignment coordinate marks with a specific shape composed of concave and / or convex shapes. The nano-contact sensor on the lithography system can identify and record the in-situ coordinates on the wafer in the write field exposure zone. When the wafer moves out of the write field (e.g., the first write field) with the lateral, longitudinal, or combined movement of the wafer stage, the actual coordinates of the wafer in the write field area after it has been moved out can be re-identified and recorded by the nano-contact sensor. The computer system on the lithography system can compare and process the errors caused by the movement of the stage and the electron beam drift, thereby determining the exposure area error correction parameters for the next write field (e.g., the second write field), so that the wafer part of the next write field (the second write field) is exposed with an electron beam after the exposure coordinate correction. In this way, the second write field will be precisely matched and stitched with the write field (first write field) that was previously removed from the exposure area by an additional offset corrected by the electron beam. After the second write field is exposed, the wafer stage moves, removing the second write field from the write field exposure area. This process is repeated, moving the wafer repeatedly, so that the wafer portions of each write field after each exposure achieve closed-loop control stitching with horizontal and / or per-error correction. This achieves sub-nanometer precision stitching of the write fields, eliminating the need for further improvements in the electromechanical processing precision of the lithography machine system stage. Even using a more common and inexpensive lithography machine system combined with the nano-nano-contact sensor detection technology and the in-situ alignment coordinate mark detection technology of this invention, which constitute the "observant" closed-loop stitching control technology, high-precision sub-nanometer wafer lithography stitching can be achieved. Moreover, the lithography machine system of this invention has low cost and low product manufacturing cost, representing a groundbreaking improvement over existing technologies.

[0126] The present invention will be further described below with reference to the accompanying drawings and embodiments. Of course, these embodiments are merely illustrative and general descriptions to illustrate the various claims, but should not be construed as limiting the rights of the present invention to these embodiments. Attached Figure Description

[0127] Figure 1a , 1b This is a schematic diagram of electron beam lithography.

[0128] Wherein: 1-Wafer (substrate); 2-Photosensitive adhesive layer; 3-The pattern produced after electron beam exposure (taking a grating as an example); 4-The electron beam emitted by the electron gun in the electron microscope tube; 5-The coordinates of the electron beam at the just-exposed position (CPJE); 6-The coordinates of the electron beam that has not been exposed but is aimed at the electron beam to be exposed.

[0129] Figures 2a-2bThese are schematic diagrams illustrating two principles of this invention: electron beam-induced photosensitive adhesive layer modification (EIRC) to expand or shrink at the sub-nanometer or nanometer scale to form uneven structures.

[0130] Wherein: 1-Wafer (substrate); 2-Photosensitive adhesive layer; 7-Photosensitive adhesive layer not exposed by electron beam; 8-Photosensitive adhesive layer EIRC exposed by electron beam (resulting in concave shrinkage); 10-Photosensitive adhesive layer EIRC exposed by electron beam (resulting in convex expansion); 9 and 11 are the scales of concave shrinkage and convex expansion in the height direction, respectively, typically ranging from sub-nanometer to several nanometers.

[0131] Figure 3 This is a schematic diagram showing the locations of the three alignment marks;

[0132] Wherein: 1-Wafer; 12-Long-distance off-field marker (RA1); 13-On-field marker (IA); 14-Off-field marker located between write fields (RA2); 15-Write field; 16-Rotation angle, X, Y are Cartesian coordinates. The wafer is moved in the XYZ direction or in the XY, YZ, XZ plane by the stage.

[0133] In conventional technology, the marker 12 and the marker 14 between the writing fields are both outside the writing field: they are a type of long-distance alignment marker (RA marker), which can only be irradiated by the electron beam by moving the stage away from the writing field.

[0134] The in-field marker used in this invention is an in-field marker (IA marker) that can be radiated within the write field without moving the wafer stage. If the in-field marker is precisely placed on or very close to the photosensitive adhesive layer / wafer below the electron beam marker (CPJE, CPTE), it can serve as an in-situ alignment marker (ISA). If these two coordinates coincide, this in-situ alignment marker constitutes an over-alignment marker (OA marker).

[0135] Figure 4 This is a schematic diagram illustrating another principle of generating a concave-convex structure according to the present invention;

[0136] Wherein: 1-wafer; 2-photosensitive adhesive layer; 392-contact of nano-contact sensor 39; 18-three-dimensional raised alignment mark (HAMR) of photosensitive adhesive layer; 19-three-dimensional raised alignment mark (HAMW) preset on wafer surface; 20-height of the three-dimensional raised mark preset on wafer surface, located below photosensitive adhesive layer 2; 21-height of the three-dimensional raised mark of photosensitive adhesive layer 2, which is caused by the transfer of the three-dimensional raised mark preset on wafer 1 surface. The shape undulation of this uneven structure can be detected by the contact 392 of nano-contact sensor 39.

[0137] Figures 5a-5cThis is a schematic diagram illustrating the process where there is a huge splicing error between the horizontal splicing of the previous and next write fields in the existing technology.

[0138] Figure 5a In the middle: 22- is the first write field, where the wafer is in the exposure position; 23- is the grating (taking the grating as the exposure pattern as an example); 24- is the alignment mark away from the write field;

[0139] The image shows the first field 22, which is the first image to enter the exposure area and await electron beam exposure.

[0140] Figure 5b In the middle: 22´- is the first writing field removed from the exposure area, becoming 22´; 22- is the position of the second writing field subsequently moved into the exposure area; 27- is the actual moving direction of the worktable 38; 28- is the planned moving direction of the worktable 38;

[0141] In the figure, the stage 38 moves, moving the first writing field out of the writing field range that can be irradiated by the electron beam, making room for the next writing field, namely the second writing field. The mechanical error of the stage 38 movement will cause splicing error.

[0142] Figure 5c In the diagram: 29X represents the horizontal (X-direction) splicing error caused by the movement of the worktable 38, and 29Y represents the vertical (Y-direction) splicing error caused by the movement of the worktable 38.

[0143] Figure 6a This is a schematic diagram of the existing technology where the wafer has not yet been removed from its original position after being exposed in the first write field 22 of the exposure area;

[0144] Figure 6b This diagram illustrates a process where a wafer is placed in the first write field 22 of the exposure area, then removed for other processing, and finally placed back into the exposure area of ​​the stage for photolithography or a second exposure. Due to errors caused by stage movement, the new position 22' of the first write field deviates. At this point, the write field in the electron beam exposure area becomes the second write field, which is the original write field position 22. The write field 22' does not coincide with the second write field, resulting in a vertical alignment error.

[0145] Figures 7a-7b This is a schematic diagram describing and characterizing the electron beam through electron beam-induced photosensitive adhesive layer 2 modification (EIRC);

[0146] Figure 7a In the middle: 1-wafer; 2-photosensitive adhesive layer 2; 17-electron beam; 29-the electron beam focusing point exposed by the exposure point of photosensitive adhesive layer 2;

[0147] Figure 7bIn the middle: 1-wafer; 2-photosensitive adhesive layer 2; 17-electron beam; 17'-position of the electron beam after drifting over time; 30-the focal point of the electron beam irradiation after the exposure point of photosensitive adhesive layer 2.

[0148] Figure 8 This is a schematic diagram of the sub-nanometer-level high-precision write field splicing lithography system of the present invention;

[0149] Figure 9a , Figure 9b , Figure 9c , Figure 9d , Figure 9e , Figure 9f This is a schematic diagram illustrating the splicing alignment method of the present invention, taking horizontal splicing as an example;

[0150] Figure 9a After the wafer in the first write field 22-1 has been exposed but before it has moved out of the exposure area, the position coordinates of six in-situ alignment coordinate markers are measured using a nano-contact sensor (for example): C1L1, C1L2, C1L3 and C1R1, C1R2, C1R3. Where: C1 represents the first write field, Lx represents the left coordinate of the write field, and Rx represents the right coordinate of the write field.

[0151] Figure 9b After the wafer is exposed in the first writing field 22-1, it is moved out of the exposure area 22 to become the writing field 22-1'. The position coordinates of the above-mentioned in-situ alignment coordinate mark after the movement are measured by the nano-contact sensor: C1L1'-L3' and C1R1'-R3'. The next writing field that is subsequently moved into the exposure area 22 is the second writing field (writing field 22-2). The electron beam scanning exposure area is still in 22-1, which is the current writing field 22-2.

[0152] The wafer stage moves, and the second write field cannot be exposed at this position due to splicing error. Its coordinates are C2L1-L3 and C2R1-R3. After the stage moves, the pattern related to the write field 22-1' is moved to the left of the second write field that will be exposed later. The corresponding coordinates measured by the nano-contact sensor after the movement are C1L1'-L3' and C1R1'-R3'.

[0153] Figure 9c It is a schematic diagram of the position of the corrected second writing field 22-2', which is the writing field of the actual exposure area after the first writing field 22-1 is exposed and moved out of the exposure area to become writing field 22-1', and the actual writing field 22-1 is not moved out of the exposure area after the first writing field 22-1 is exposed. The error correction value is obtained by negative feedback adjustment and correction.

[0154] The coordinates of the corrected second write field 22-2' are: C2L1', C2L2', C2L3' and C2R1', C2R2', C2R3', and: C2L1' is the same as C1R1', C2L2' is the same as C1R2', and C2L3' is the same as C1R3', that is, the corrected second write field 22-2' and write field 22-1' achieve precise docking.

[0155] Figure 9c It is a schematic diagram of the position of the corrected second writing field 22-2', which is the writing field of the actual exposure area after the first writing field 22-1 is exposed and moved out of the exposure area to become writing field 22-1', and the actual writing field 22-1 is not moved out of the exposure area after the first writing field 22-1 is exposed. The error correction value is obtained by negative feedback adjustment and correction.

[0156] The coordinates of the corrected second write field 22-2' are: C2L1', C2L2', C2L3' and C2R1', C2R2', C2R3', and: C2L1' is the same as C1R1', C2L2' is the same as C1R2', and C2L3' is the same as C1R3', that is, the corrected second write field 22-2' and write field 22-1' achieve precise docking.

[0157] Figure 9d The stage moved for the first time, seamlessly merging the second and first writing fields. Then, the stage moved a second time, creating new exposure area space 22-3'. The coordinates of the first writing field, due to the second stage movement, became C1Lx'', C1Rx'', while the coordinates of the second writing field also shifted to C2Lx'', C2Rx''. The corresponding coordinates of 22-3' are C3Lx', C3Rx'. The electron beam exposure area remains at 22-2'.

[0158] Figure 9e The electron beam acquires the coordinate deviation value of the third writing field of the exposure. Through electron beam coordinate compensation, the exposure area is moved to be close to the 22-2´´ writing field. Then, the third writing field exposure is performed.

[0159] Figure 9f The worktable moves for the third time. 22-1´´ moves accordingly to become 22-1´´´, 22-2´´ moves accordingly to become 22-2´´´, and 22-3´´ moves accordingly to become 22-3´´´. This frees up exposure space 22-4´´ (at the position of 22-3´´).

[0160] Figure 10a , 10b This is a schematic diagram of using two nano-contact sensors to measure the in-situ alignment coordinate marks to achieve splicing alignment, in order to achieve a faster measurement speed;

[0161] in Figure 10aThe contacts 392 of the two sets of nano-contact sensors 39 are placed on both sides of the write field 22, which facilitates the wafer's movement through the stage, either to the left or to the right for splicing. At this time, the write field 22 has been exposed but has not yet moved out of the exposure area. The contacts 392 of the two sets of nano-contact sensors measure the pre-set in-situ alignment coordinate markers C1L1, C1L2, C1L3 and C1R1, C1R2, C1R3 on the write field 22; each set of nano-contact sensors 39, for example, contains three vertical contacts 392.

[0162] Figure 10b This diagram illustrates the process by which two sets of nano-contact sensors move to both sides of the writing field 22-1' to measure the in-situ alignment coordinate markers C1L1', C1L2', C1L3' and C1R1', C1R2', C1R3' on the wafer that has moved out of the exposure area and is now at the writing field 22-1' position. This allows for the calculation of error correction values ​​for the wafers subsequently entering the writing field 22-2, and the adjustment of the exposure deflection parameters and focus point of the electron gun in the electron microscope tube, so that the stitching coordinates of the corrected writing field 22-2' precisely match those of the writing field 22-1'.

[0163] Figure 11 This is a schematic diagram of a method for achieving longitudinal layer alignment and splicing by using a three-dimensional protrusion structure 43 and a three-dimensional structure 44 of the photosensitive adhesive layer as three-dimensional in-situ alignment coordinate markers, and a method for achieving longitudinal layer alignment and splicing by using an electron beam 4 to measure exposure offset error.

[0164] First, a raised three-dimensional alignment mark 43 is pre-set on the wafer to be photolithographically processed. Then, a photosensitive adhesive layer is coated on it so that a corresponding raised three-dimensional alignment mark 44 is also generated at the position where the pre-set three-dimensional alignment mark is located.

[0165] A wafer with three-dimensional alignment marks is moved via a wafer stage 38 to a write field area that can be exposed by an electron beam. The electron beam is then aligned with the three-dimensional alignment mark 44 (position 1) on the photosensitive adhesive layer for spot exposure. This produces a potentially misaligned three-dimensional mark 45 (position 2) on the exposed point of the photosensitive adhesive layer. By measuring positions 1 and 2 using a nano-contact sensor, the correction value for the write field exposure area can be calculated. This allows the electron gun to be controlled to achieve precise longitudinal alignment and exposure, thereby enabling accurate stitching.

[0166] Figure 12 This is a schematic diagram illustrating the rapid assembly and alignment of nano-contact sensors, each equipped with multiple nano-contacts.

[0167] The nano-contact sensor 39 has two rows of sensing arms, with four nano-contacts in each row. Example

[0168] See Figure 1. Figure 8 A sub-nanometer high-precision write field stitching lithography system is constructed, comprising a sealed, stationary electron microscope body 31, a stage 37 within the body 31, an electron microscope, at least one nanometer contact sensor 39, and a wafer stage 38. The electron microscope is equipped with an electron beam tube 32, an electron gun 372, a focusing system 33, deflection coils 35, etc. The wafer stage 38 is equipped with a CNC drive device 371 for moving it forward, backward, and / or left, right, and / or up, down, as well as for changing its angle.

[0169] The control computer 42 is connected to the electron microscope tube and the nano-contact sensor 39 via an electron beam control system 34 and a pattern generator 46. The nano-contact sensor 39 transmits the in-situ alignment coordinate identification signal 40 and / or electron beam drift signal 40 acquired from the wafer under test to the pattern generator 46 under the control of the control computer 42. The pattern generator 46, under the control of the control computer 42, sends the processed and corrected electron beam scanning control signal to the electron beam control system 34. The electron beam control system 34 controls the shutter of the focusing system 33 on the electron beam tube 32 and the deflection coil 35 that controls the electron beam deflection. Since the structure and working principle of the electron microscope and the nano-contact sensor are well known, further explanation of the electron microscope and the nano-contact sensor is not provided here.

[0170] A secondary electron imaging signal acquisition device 36 can also be installed on the electron beam tube 32, which is used to feed back the acquired secondary image after electron beam scanning to the control computer 42 for video display via the electron beam control system 34.

[0171] The nano-contact sensor 39 possesses sub-nanometer measurement accuracy and can be selected from one or more of atomic force tip sensors or nanoscale surface work function measurement sensors. The nano-contact sensor 39 is mounted within the sample chamber of the electron beam lithography system, enabling sub-nanometer precision and excellent spatial repeatability in measuring the three-dimensional surface morphology. The nano-contact sensor is located next to the electron beam tube 32, near the electron beam focal point and above the surface of the photosensitive adhesive layer.

[0172] The nano-contact sensor 39 is provided with a lever-type sensing arm 391, and the sensing arm 391 is provided with a needle-tip sensing contact 392, see [link / reference] Figure 8 .

[0173] Each contact arm 391 is provided with at least one row of needle tip sensing contacts 392, and each row is provided with more than one number of needle tip sensing contacts 392.

[0174] Taking Figure 10 as an example, it is provided with two rows of needle tip sensing contacts 392, with one needle tip sensing contact 392 in each row, and the two rows are arranged on both sides of the electron beam tube 32.

[0175] Figure 12 For example, it has two rows of needle tip sensing contacts 392, with four needle tip sensing contacts 392 in each row.

[0176] The electron beam tube 32 is directly facing the exposure area 22 of the wafer on the wafer stage 38.

[0177] At the beginning of implementing the method of the present invention, it is necessary to pre-process the wafer, that is, to coat the wafer 1 with a photosensitive adhesive layer 2 to be exposed, and to provide in-situ alignment coordinate marks 8, 10, 44 or 45 in the write field area of ​​the wafer 1 and / or its photosensitive adhesive layer 2, which are made of concave and / or convex shapes and have specific shapes for the nano-contact sensor 39 to identify in-situ coordinates after electron beam exposure.

[0178] This in-situ alignment coordinate marker can be a planar structural graphic marker, and there can be 1, 2, 3, 4, 5, 6 or more of them arranged on a plane, or even more. In this embodiment, the planar structural graphic marker is preferably formed by the minute geometrical changes produced by the electron beam inducing the surface of the photoresist layer. Planar structural graphic markers with similar effects formed by other known technologies can also be used, and will not be elaborated here.

[0179] In-situ alignment coordinate markers can also be made into three-dimensional shape markers. There can be 1, 2, 3, 4, 5, 6 or more of them arranged on a plane, and of course, more are also possible. Three-dimensional shape markers are best made into pyramid or cone shapes that are easy for electronic identification, but other shapes are also acceptable.

[0180] Having established the aforementioned working environment, the sub-nanometer-level high-precision photolithography write field stitching method of the present invention can be implemented, comprising the following steps:

[0181] Step 1: Inside the lithography machine system body 31, a stage 37, an electron microscope and its electron beam tube 32, an electron gun 372, a wafer moving stage 38, and at least one nano-contact sensor 39 are set up; a CNC drive device 371 to control its movement is set up on the wafer moving stage 38; before the wafer is placed into the lithography machine system, a photosensitive adhesive layer 2 is coated on the entire wafer 1, the electron beam scanning range is the exposure area 22, the exposure area is divided into several write fields, each write field on the photosensitive adhesive layer is provided with specific in-situ alignment coordinate markers 8, 10, 18, 43, and 44 that will show a predetermined shape after exposure in the exposure area; the write fields are sequentially the first write field 22-1, the second write field 22-2, ..., the nth write field 22-n. For example, if there are 1000 write fields, then n is 1000, and the wafers of 1000 write fields need to be exposed, moved, and spliced.

[0182] Step 2: Place the wafer 1 coated with photosensitive adhesive layer 2 on the stage 38, and position the first write field 22-1 of the wafer into the exposure area 22. Position the electron beam tube 32 of the electron microscope perpendicularly to the exposure area 22, and then focus the electron beam onto the write field. The first write field 22-1 refers to the first write field, the second write field 22-2 refers to the second write field, and the third write field 22-3 refers to the third write field. In “22-1´”, “´” indicates that the stage has moved once. In “22-1´´”, “´´” indicates that the stage has moved twice, meaning “22-1´´” refers to the first write field and the stage has moved the first write field twice, and so on.

[0183] Step 3: Expose a portion of the wafer on the first write field 22-1 within the exposure area 22, so that the photosensitive adhesive coated on the portion of the wafer undergoes a chemical reaction after exposure, causing electron beam-induced changes to produce at least one or a group of concave and convex structures constituting a pattern. The specific shape of the concave and convex structure serves as the feature shape of the pre-set in-situ alignment coordinate marker, and the coordinate values ​​of its feature points within the exposure area are used as the in-situ alignment coordinates.

[0184] Step 4: Activate the nano-contact sensor (39) to first measure the surface shape of the concave-convex structure, then identify the alignment coordinate marks by referring to the preset specific shape, and then determine and memorize their coordinate values ​​on the worktable, for example: (C1L1;C1L2;C1L3;C1R1;C1R2;C1R3). In principle, more than one of these coordinate points can be arbitrarily selected within the writing field (the same applies below).

[0185] Step 5: Preparation before exposure of the second write field. The moving stage 38 moves the wafer 1 horizontally and / or vertically, thereby moving the first write field area 22-1 that has just been exposed out of the exposure area to become write field 22-1', making room for the second write field 22-2 of the wafer to enter the exposure area.

[0186] Step 6: Activate the nano-contact sensor 39 to identify the alignment coordinate mark within the first write field 22-1' that has been removed from the exposure area, determine and memorize the first write field position coordinates (C1L1';C1L2';C1L3';C1R1';C1R2';C1R3') on the worktable after its movement.

[0187] Step 7: Using the data of the alignment coordinate markers within the first writing field 22-1´ after the movement as the basis for closed-loop feedback control, calculate the actual coordinate deviation before and after the writing field movement, and then determine the coordinate correction value of the entire exposure area in the next electron beam frame.

[0188] Let C1R1' be the coordinate of the second write field 22-2', which is adjacent to the first write field 22-1' that has been moved out of the exposure area and is about to be exposed after error correction. That is, the coordinate X C1R1´ Y C1R1´ This is also the new coordinate that the second writing field 22-2´, which will soon be revealed, needs to be seamlessly spliced ​​to the new coordinates of the moved first writing field 22-1´, that is:

[0189] (X) C2L1´ Y C2L1´ ):X C2L1´ =X C1R1´ Y C2L1´ =Y C1R1´ ;

[0190] The electron beam is now aimed at the second writing field 22-2 located within the exposure area 22 before error correction, whose coordinates are C2L1, i.e., coordinates (X... C2L1 Y C2L1 Since this coordinate point needs to be stitched and corrected for exposure by applying a deflection voltage to the electron beam to fit the edge coordinate C1R1' of the already moved first write field 22-1', the relevant coordinate point of the second write field 22-2 is C2L1' after correction. The coordinate difference between C2L1' and C2L1 is:

[0191] ΔX1= X C2L1´ - X C2L1 = X C1R1´ - X C2L1

[0192] ΔY1= Y C2L1´ - Y C2L1 = Y C1R1´ - Y C2L1

[0193] Given the second writing field and its coordinate X C2L1 Y C2L1 Since the worktable has not moved and exposure has not yet occurred, it is impossible to obtain the desired results. Therefore, the overall electron beam drift in the exposure area of ​​the first and second writing fields is initially ignored. This ensures that the coordinates of the second writing field 22-2 before exposure and before correction are equivalent to the coordinates of the first writing field 22-1 during exposure: X C2L1 =X C1L1 Y C2L1 =Y C1L1 This allows the coordinates to be measured using the uneven structure formed on the surface of the photosensitive adhesive layer due to exposure before the stage moves after the first writing field exposure, thus obtaining the coordinate difference that needs to be compensated for when correcting all electron beam coordinate points in the second writing field:

[0194] ΔX1= X C1R1´ - X C1L1

[0195] ΔY1= Y C1R1´ - Y C1L1。

[0196] Step 8: Adjust the deflection voltage of the electron beam tube 32 according to the obtained coordinate difference (ΔX1, ΔY1) that needs to be compensated for during correction. Correct the stitching coordinates (C2L1;C2L2;C2L3;C2R1;C2R2;C2R3;) of the second write field 22-2 of the wafer that subsequently enters the exposure area so that they are corrected to the adjacent stitching coordinates (C2L1´;C2L2´;C2L3´;C2R1´;C2R2´;C2R3´) of the first write field after the movement. The corrected stitching coordinates of the second write field 22-2´ are seamlessly connected with the first write field after the movement.

[0197] Step 9: Perform electron beam exposure on the wafer portion of the second write field 22-2´ placed in the exposure area after electron beam exposure coordinate correction, so that the photosensitive adhesive coated on the exposed wafer portion undergoes a chemical reaction to reveal the preset alignment coordinate mark in the write field characterized by a specific concave-convex structure.

[0198] Step 10: Activate the nano-contact sensor 39 to identify the above alignment coordinate mark by comparing it with the preset specific shape, determine and memorize the position coordinates of the feature coordinate point in the second writing field 22-2´ after correction on the worktable (C2L1´;C2L2´;C2L3´;C2R1´;C2R2´;C2R3´).

[0199] Step 11: Prepare for the exposure of the third write field. Move the stage 38 again to move the wafer 1 horizontally and / or vertically, so that the previously moved first write field 22-1' and the newly exposed corrected second write field 22-2' are both moved. Move the newly exposed corrected second write field out of the exposure area. Through the movement of the stage, the position coordinates of the previously moved first write field 22-1' change to become the second moved first write field 22-1'. The position coordinates change from (C1Lx', C1Rx') to (C1Lx'', C1Rx''). The position coordinates of the corrected second write field that is moved out of the exposure area change from (C2Lx', C2Rx') to (C2Lx'', C2Rx''). This second write field becomes the moved second write field (22-2''), making room for the subsequent movement of the wafer's third write field (22-3') into the exposure area.

[0200] Step 12: Reactivate the nano-contact sensor 39 to identify the alignment coordinate mark in the second writing field 22-2´´ of the above-mentioned removed exposure area, determine and memorize its position coordinates on the worktable 38 (C2L1´´; C2L2´´; C2L3´´; C2R1´´; C2R2´´; C2R3´´).

[0201] Step 13: Using the alignment coordinate data within the second write field after the movement as the basis for closed-loop feedback control, calculate the deviation of the actual coordinates before and after the movement, and then determine the correction values ​​ΔX2 and ΔY2 for the write field of the next electron beam exposure area:

[0202] Let the coordinates of the third write field, which is adjacent to the second write field after it has been moved out of the exposure area and is about to be exposed, be C2R1´´, i.e., coordinates (X... C2R1´´ Y C2R1´´ This is also the correction coordinate for the third writing field, which will soon be revealed, to be seamlessly stitched into the moved second writing field, i.e., (X... C3L1´´ Y C3L1´´ ):X C3L1´´ =X C2R1´´ Y C3L1´´ =Y C2 R1´´ ;

[0203] The electron beam is currently pointing towards the third write field located within the exposure area at coordinates C3L1, i.e., coordinates (X... C3L1 Y C3L1 The coordinate difference between this point and the already moved second write field to be stitched and exposed is: This coordinate point is to be stitched and exposed along the edge C2 R1'' of the already moved second write field 22-2'' using an additional deflection voltage applied to the electron beam. The relevant coordinate point of the corrected third write field 22-3'' is C3 L1'', and the coordinate difference between C3 L1'' and C3 L1'' is:

[0204] ΔX2= X C3L1´´ - X C3L1´ = X C2R1´´ - X C3L1´

[0205] ΔY2= Y C3L1´´ - Y C3L1´ = Y C2R1´´ - Y C3L1´ ;

[0206] The overall electron beam drift in the exposure area for both the second and third writing fields is neglected, ensuring that the coordinates of the third writing field before exposure coordinate correction are identical to those of the second writing field during exposure: X C3L1´ =X C2L1´ Y C3L1´ =Y C2L1´ This allows the coordinates to be measured using the uneven structure formed on the surface of the photosensitive adhesive layer due to exposure before the stage moves after the second write field exposure, thus obtaining the coordinate difference that needs to be compensated for for electron beam coordinate correction of all write field exposure points:

[0207] ΔX2= X C2R1´´ - X C2L1´

[0208] ΔY2= Y C2R1´´ - Y C2L1´。

[0209] Step 14: Adjust the deflection voltage of the electron beam tube 32 according to the obtained correction value, and correct the electron beam exposure area so that the coordinates of all exposure points of the third write field of the subsequent wafer are consistent with the splicing coordinates of the moved second write field and seamlessly connected.

[0210] Step 15: Repeat the process to complete the exposure, movement, and stitching of the entire write field area of ​​the wafer.

[0211] In this embodiment:

[0212] An electron beam can also be an ion beam, a photon beam, or an atomic beam.

[0213] The nano-contact sensor 39 can be one or a combination of atomic force tip sensors or nanoscale surface work function measurement sensors.

[0214] In-situ alignment coordinate markers 8, 10, and 18 can be planar structural graphic markers, with 1, 2, 3, 4, 5, or 6 markers on a single plane, or more as needed. The term "planar structural graphic marker" is used broadly, specifically including graphic markers formed by minute geometrical changes on the surface of the photoresist layer induced by an electron beam.

[0215] In this embodiment, a graphic identifier formed by the minute geometrical changes on the surface of the photoresist layer induced by an electron beam is used as a planar structural graphic identifier.

[0216] In-situ alignment coordinate markers 43 and 44 can also be three-dimensional markers, preferably in the shape of a pyramid or cone. There can be 1, 2, 3, 4, 5, 6 or more of these markers on a plane.

[0217] In this embodiment, 1-4 nano-contact sensors are preferably distributed around the exposure area.

[0218] The nano-contact sensor 39 is provided with a lever-type sensing arm 391, and the arm 391 is provided with one or more needle-tip sensing contacts 392 arranged in a row.

[0219] Either a Gaussian beam or a deformed beam can be used as the electron beam.

[0220] Methods for measuring electron beam drift, such as Figure 7a , 7b The process includes the following steps: Inside the lithography machine system body 31, a stage 37, an electron microscope and its electron gun 372, a wafer moving stage 38, and a nano-contact sensor 39 are first set up; a CNC drive device 371 to control its movement is set on the wafer moving stage 38, and a photosensitive adhesive layer is coated on the wafer. Then, an electron beam 17 is emitted by the electron gun 372 and focused onto the photosensitive adhesive layer, exposing it. Through exposure, a minute change in the geometric shape of the uneven structure caused by the electron beam is generated on the surface of the photosensitive adhesive layer. This minute change is measured and the drift of the focus point over time is tracked. The coordinate values ​​and drift amount of the electron beam drift trajectory 30 over time are recorded. Based on the recorded coordinate values ​​and drift amount of the electron beam drift trajectory 30 over time, the exposure coordinate values ​​and correction compensation difference caused by the drift of the electron beam over time during the start and end time intervals are calculated, and the correction coordinates for the next write field exposure are obtained.

[0221] like Figure 8 As shown, the nano-contact sensor 39 is provided with a lever-type sensing arm 391, and the arm 391 is provided with one or more needle-tip sensing contacts 392 arranged in a row.

[0222] The sub-nanometer high-precision photolithography writing field longitudinal stitching method is as follows: Figure 11 As shown: First, a raised three-dimensional alignment mark 43 is pre-set on the wafer to be photolithographically processed. Then, a photosensitive adhesive layer 2 is coated on it, so that a corresponding raised three-dimensional alignment mark 44 is also generated at the position of the pre-set three-dimensional alignment mark. Then, the wafer 1 with the three-dimensional alignment mark is moved to the write field area that can be exposed by the electron beam 4 through the wafer stage 38. The electron beam 4 is aligned with the position of the photosensitive adhesive layer three-dimensional alignment mark 44 to perform point exposure. A three-dimensional mark 45 with actual deviation is generated outside the exposure point of the photosensitive adhesive layer. Then, the actual coordinate values ​​of the three-dimensional alignment mark 44 and the deviated three-dimensional mark 45 are measured by the photosensitive adhesive layer using a nano-contact sensor. Then, the correction value of the write field exposure area is calculated, thereby controlling the electron gun to achieve precise longitudinal alignment and exposure, and achieving precise longitudinal splicing.

[0223] Figure 12 This is a schematic diagram illustrating the rapid splicing and alignment of nano-contact sensors, each of which has multiple nano-contacts 392 on it.

Claims

1. A sub-nanometer high-precision photolithography write field stitching method, characterized in that... The method includes the following steps: Step 1: Inside the lithography machine system body (31), set up the stage (37), electron microscope and its electron gun (372), wafer moving stage (38) and at least one nano-contact sensor (39); set up the CNC drive device (371) to control its movement on the wafer moving stage (38); before the wafer is placed into the lithography machine system, coat the entire wafer (1) with a photosensitive adhesive layer (2), the electron beam scanning range is the exposure area (22), divide the exposure area into several write fields, and each write field on the photosensitive adhesive layer is provided with specific in-situ alignment coordinate marks (8, 10, 18, 43, 44) that will be exposed in a predetermined shape after exposure in the exposure area; the write fields are sequentially the first write field (22-1), the second write field (22-2), ..., the nth write field (22-n); Step 2: Place the wafer (1) coated with photosensitive adhesive layer (2) on the worktable (38) and make the first writing field (22-1) of the wafer fall into the exposure area (22). Make the electron beam tube (32) of the electron microscope perpendicular to the exposure area (22) and then focus the electron beam on the writing field. Step 3: Expose a portion of the wafer on the first write field (22-1) within the exposure area (22), so that the photosensitive adhesive coated on the portion of the wafer undergoes a chemical reaction after exposure, causing an electron beam-induced change to produce at least one or a group of concave and convex structures constituting a pattern. The specific shape of the concave and convex structure is used as the feature shape of the pre-set in-situ alignment coordinate mark, and the coordinate values ​​of its feature points in the exposure area are used as the in-situ alignment coordinates. Step 4: Activate the nano-contact sensor (39) to first measure the surface shape of the concave-convex structure, then identify the above alignment coordinate mark by referring to the preset specific shape, and then determine and memorize its coordinate value on the worktable (C1L1;C1L2;C1L3;C1R1;C1R2;C1R3). Step 5: Prepare for the second writing field exposure by moving the worktable (38) to move the wafer (1) horizontally and / or vertically, so that the first writing field area (22-1) that has just been exposed is moved out of the exposure area to become writing field 22-1', making room for the second writing field (22-2) of the wafer to enter the exposure area. Step 6: Activate the nano-contact sensor (39) to identify the alignment coordinate mark in the first write field (22-1') that was removed from the exposure area, determine and memorize the first write field position coordinates (C1L1';C1L2';C1L3';C1R1';C1R2';C1R3') on the worktable after the movement. Step 7: Using the alignment coordinate marker data within the first write field (22-1') after the shift as the basis for closed-loop feedback control, calculate the actual coordinate deviation before and after the write field shift, and then determine the coordinate correction value for the entire exposure area in the next electron beam frame: Let C1R1' be the coordinate of the second write field (22-2') that is adjacent to the first write field (22-1') which has been removed from the exposure area and is about to be exposed after error correction. That is, the coordinate (X) C1R1´ Y C1R1´ This is also the new coordinate of the second writing field (22-2´) that will soon be revealed, which needs to be seamlessly spliced ​​to the new coordinates of the first writing field (22-1´) after it has been moved. (X C2L1´ ,AND C2L1´ ):X C2L1´ =X C1R1´ ,AND C2L1´ =Y C1R1´ ; The electron beam is now pointing at the second writing field (22-2) located in the exposure area (22) before error correction, with coordinates C2L1, i.e., coordinates (X... C2L1 Y C2L1 Since this coordinate point needs to be stitched and corrected for exposure by applying a deflection voltage to the electron beam to fit the edge coordinate C1R1' of the already moved first write field (22-1'), the relevant coordinate point of the second write field (22-2) is C2L1', and the coordinate difference between C2L1' and C2L1 is: ΔX1= X C2L1´ - X C2L1 = X C1R1´ - X C2L1 ΔY1= Y C2L1´ - AND C2L1 = And C1R1´ - AND C2L1 Given the second writing field and its coordinates (X) C2L1 Y C2L1 Since the worktable has not moved and exposure has not yet occurred, it is impossible to obtain the coordinates. Therefore, the overall electron beam drift in the exposure area of ​​the first and second writing fields is ignored. This makes the coordinates of the second writing field (22-2) before exposure and before correction equivalent to the coordinates of the first writing field (22-1) during exposure. C2L1 =X C1L1 Y C2L1 =Y C1L1 This allows the coordinates to be measured using the uneven structure formed on the surface of the photosensitive adhesive layer due to exposure before the stage moves after the first writing field exposure, thus obtaining the coordinate difference that needs to be compensated for when correcting all electron beam coordinate points in the second writing field: ΔX1= X C1R1´ - X C1L1 ΔY1= Y C1R1´ - AND C1L1 ; Step 8: Adjust the deflection voltage of the electron beam tube (32) according to the obtained coordinate difference (ΔX1, ΔY1) that needs to be compensated for, and correct the electron beam exposure area so that the splicing coordinates (C2L1;C2L2;C2L3;C2R1;C2R2;C2R3;) of the second write field (22-2) of the wafer that subsequently enters the exposure area are corrected to be adjacent to the splicing coordinates of the moved first write field. The corrected splicing coordinates of the second write field (22-2´) are seamlessly connected with the moved first write field.

2. The sub-nanometer high-precision photolithography write field stitching method according to claim 1, characterized in that... It also includes the following steps: Step 9: Perform electron beam exposure on the wafer portion of the second write field (22-2´) placed in the exposure area after electron beam exposure coordinate correction, so that the photosensitive adhesive coated on the exposed wafer portion undergoes a chemical reaction to reveal the preset alignment coordinate mark in the write field characterized by a specific concave-convex structure. Step 10: Activate the nano-contact sensor (39) to identify the above alignment coordinate mark by referring to the preset specific shape, determine and memorize the position coordinates of the feature coordinate point in the corrected second writing field (22-2´) on the worktable (C2L1´;C2L2´; C2L3´; C2R1´; C2R2´; C2R3´). Step 11: Prepare for the exposure of the third writing field. Move the stage (38) again to move the wafer (1) horizontally and / or vertically, so that the first writing field (22-1´) that was moved before and the corrected second writing field (22-2´) that was just exposed are both moved. Move the corrected second writing field that was just exposed out of the exposure area. By moving the stage, the position coordinates of the first writing field (22-1´) that was moved before change and become the first writing field (22-1´) that was moved twice. The position coordinates change from (C1Lx´,C1Rx´) to (C1Lx´´,C1Rx´´). The position coordinates of the second writing field that was moved out of the exposure area after correction change from (C2Lx´,C2Rx´) to (C2Lx´´,C2Rx´´). This second writing field becomes the second writing field (22-2´´) after movement, making room for the third writing field (22-3´) of the wafer to move into the exposure area. Step 12: Reactivate the nano-contact sensor (39) to identify the alignment coordinate markers in the second writing field (22-2´´) of the above-mentioned removed exposure area, determine and memorize its position coordinates on the worktable (38) (C2L1´´; C2L2´´; C2L3´´; C2R1´´; C2R2´´; C2R3´´). Step 13: Using the alignment coordinate data within the second write field after the movement as the basis for closed-loop feedback control, calculate the deviation of the actual coordinates before and after the movement, and then determine the correction values ​​ΔX2 and ΔY2 for the write field of the next electron beam exposure area: Let the coordinates of the third write field, which is adjacent to the second write field after it has been moved out of the exposure area and is about to be exposed, be C2R1´´, i.e., coordinates (X... C2R1´´ Y C2R1´´ This is also the calibration coordinate that the third writing field, which will soon be revealed, needs to be seamlessly stitched into the moved second writing field, namely: (X C3L1´´ ,AND C3L1´´ ):X C3L1´´ =X C2R1´´ ,AND C3L1´´ =Y C2 R1´´ ; The electron beam is currently pointing towards the third write field located within the exposure area at coordinates C3L1, i.e., coordinates (X... C3L1 Y C3L1 The coordinate difference between this point and the already moved second write field (22-2´´) to be stitched and exposed is C2 R1´´. The relevant coordinate point of the corrected third write field (22-3´´) is C3 L1´´, and the coordinate difference between C3 L1´´ and C3 L1´´ is: ΔX2= X C3L1´´ - X C3L1´ = X C2R1´´ - X C3L1´ ΔY2= Y C3L1´´ - Y C3L1´ = Y C2R1´´ - Y C3L1´ ; The overall electron beam drift in the exposure area for both the second and third writing fields is neglected, ensuring that the coordinates of the third writing field before exposure coordinate correction are identical to those of the second writing field during exposure: X C3L1´ =X C2L1´ Y C3L1´ =Y C2L1´ This allows the coordinates to be measured using the uneven structure formed on the surface of the photosensitive adhesive layer due to exposure before the stage moves after the second write field exposure, thus obtaining the coordinate difference that needs to be compensated for for electron beam coordinate correction of all write field exposure points: ΔX2= X C2R1´´ - X C2L1´ ΔY2= Y C2R1´´ - Y C2L1´ ; Step 14: Adjust the deflection voltage of the electron beam tube (32) according to the obtained correction value, and correct the electron beam exposure area so that the coordinates of all exposure points of the third write field of the subsequent wafer are aligned with the splicing coordinates of the moved second write field and seamlessly connected. Step 15: Repeat the process to complete the exposure, movement, and stitching of the entire write field area of ​​the wafer.

3. The sub-nanometer high-precision photolithography write field stitching method according to claim 1, characterized in that... The electron beam can also be an ion beam, a photon beam, or an atomic beam.

4. The sub-nanometer high-precision photolithography write field stitching method according to claim 1, characterized in that... The nano-contact sensor (39) is one or more of an atomic force tip sensor or a nanoscale surface work function measurement sensor.

5. The sub-nanometer high-precision photolithography write field stitching method according to claim 1, characterized in that... The wafer includes a complete wafer, a partial wafer, or non-wafer material that requires photolithography write field splicing.

6. The sub-nanometer high-precision photolithography write field stitching method according to claim 1, characterized in that... The in-situ alignment coordinate markers (8, 10, 18) are planar structural graphic markers.

7. The sub-nanometer high-precision photolithography write field stitching method according to claim 6, characterized in that... The planar structural graphic identifier has 1, 2, 3, 4, 5, 6 or more on a plane.

8. The sub-nanometer high-precision photolithography write field stitching method according to claim 6, characterized in that... The planar structural graphic identifier includes a graphic identifier formed by minute geometrical changes on the surface of the photoresist layer induced by an electron beam.

9. The sub-nanometer high-precision photolithography write field stitching method according to claim 1, characterized in that... The in-situ alignment coordinate markers (43, 44) are three-dimensional shape markers.

10. The sub-nanometer high-precision photolithography write field stitching method according to claim 9, characterized in that... The three-dimensional shape identifier is pyramidal or conical, and there are 1, 2, 3, 4, 5, 6 or more of these identifiers on a plane.

11. The sub-nanometer high-precision photolithography write field stitching method according to any one of claims 1-10, characterized in that... The nano-contact sensors (39) are provided in units of 1, 2, 3 or 4 or more, distributed around the exposure area.

12. The sub-nanometer high-precision photolithography write field stitching method according to claim 11, characterized in that... The nano-contact sensor (39) is provided with a lever-type sensing arm (391), and the arm (391) is provided with one or more needle-tip sensing contacts (392) arranged in a row.

13. The sub-nanometer high-precision photolithography write field stitching method according to any one of claims 1-10, characterized in that... The electron beam is a Gaussian beam.

14. The sub-nanometer high-precision photolithography write field stitching method according to any one of claims 1-10, characterized in that... The electron beam is a deformed beam.

15. A sub-nanometer high-precision write field stitching lithography system for any of the sub-nanometer high-precision write field stitching methods of claims 1-14, comprising a stationary body (31) and a stage (37) within the body, wherein an electron microscope, at least one nano-contact sensor (39), and a wafer moving stage (38) are provided above the stage; the electron microscope is provided with an electron beam tube (32), which is directly facing the exposure area (22) of the wafer on the wafer moving stage (38), and the exposure area is divided into several A writing field; the wafer stage (38) is provided with a CNC drive device (371) for dragging it forward, backward and / or left, right and / or up, down and angle changes; the nano-contact sensor (39) is provided with a sensing contact (392), the sensing contact is located above the wafer stage (38), so that the sensing contact (392) of the nano-contact sensor can sense the in-situ alignment coordinate marks (8, 10, 18, 43, 44) with a predetermined shape pre-placed under the photosensitive adhesive layer in the writing field.

16. The sub-nanometer high-precision write field stitching lithography system according to claim 15, characterized in that... The lithography system also includes a control computer (42), which is connected to a pattern generator (46), an electron beam control system (34), and a numerical control drive device (371) of the wafer stage (38). The nano-contact sensor (39) sends the in-situ alignment coordinate identification signal and / or electron beam drift signal (40) collected on the wafer under test to the pattern generator (46) under the control of the control computer (42). The pattern generator (46) sends the processed and corrected electron beam scanning control signal to the electron beam control system (34) under the control of the control computer (42). The electron beam control system (34) controls the shutter of the focusing system (33) on the electron beam barrel (32) and the deflection coil (35) that controls the deflection of the electron beam.

17. The sub-nanometer high-precision write field stitching lithography system according to claim 16, characterized in that... The nano-contact sensor (39) is located on the side of the electron beam tube (32). The electron beam tube (32) is also equipped with a secondary electron imaging signal acquisition device (36), which feeds back the acquired secondary image after electron beam scanning to the control computer (42) via the electron beam control system (34).

18. The sub-nanometer high-precision write field stitching lithography system according to claim 15, characterized in that... The nano-contact sensor (39) is one or more of an atomic force tip sensor or a nanoscale surface work function measurement sensor.

19. The sub-nanometer high-precision write field stitching lithography system according to claim 15, characterized in that... The nano-contact sensor (39) is provided with a lever-type sensing arm (391), and the arm (391) is provided with a needle tip sensing contact (392).

20. The sub-nanometer high-precision write field stitching lithography system according to claim 19, characterized in that... Each of the said contact arms (391) is provided with one or more needle tip sensing contacts (392).

21. The sub-nanometer high-precision write field stitching lithography system according to claim 19, characterized in that... Each of the aforementioned contact arms (391) is provided with at least one row of needle tip sensing contacts, and each row is provided with more than one number of needle tip sensing contacts (392).

22. The sub-nanometer high-precision write field stitching lithography system according to any one of claims 15 to 21, characterized in that... The nano-contact sensors (39) are arranged in two rows, with four sensors in each row, and the two rows are arranged on both sides of the electron beam tube (32).

23. A pre-processed wafer specifically for the sub-nanometer high-precision photolithography write field stitching method according to any one of claims 1-14, wherein the wafer is provided with an exposure area, characterized in that, A photosensitive adhesive layer to be exposed is coated on the wafer. Several write fields are provided in the exposure area. In the write field area located on the photosensitive adhesive layer, there is a sensing contact (392) of a nano-contact sensor with a specific shape composed of concave and / or convex shapes, which is provided above the wafer stage (38) to sense the in-situ alignment coordinate marks (8, 10, 18, 43, 44) of the specific shape in the write field.

24. The pre-processed wafer according to claim 23, characterized in that... The in-situ alignment coordinate markers (8, 10) are planar structural graphic markers.

25. The pre-processed wafer according to claim 24, characterized in that... The planar structural graphic identifier has 1, 2, 3, 4, 5, 6 or more on a plane.

26. The pre-processed wafer according to claim 25, characterized in that... The planar structure graphic identifier is a graphic identifier formed by minute geometrical changes on the surface of the photoresist layer induced by an electron beam.

27. The pre-processed wafer according to claim 23, characterized in that... The in-situ alignment coordinate markers (18, 19, 43, 44) are three-dimensional shape markers.

28. The pre-processed wafer according to claim 27, characterized in that... The three-dimensional shape identifiers are provided in 1, 2, 3, 4, 5, 6 or more on a plane.

29. The pre-processed wafer according to any one of claims 23 to 28, characterized in that... The wafer includes a complete wafer, a partial wafer, or non-wafer material that requires photolithography write field splicing.

30. A sub-nanometer high-precision photolithography write field longitudinal stitching method based on any one of the sub-nanometer high-precision photolithography write field stitching methods in claims 1-14, characterized in that: The process includes the following steps: Inside the body (31) of the lithography system, a stage (37), an electron microscope and its electron gun (372), a wafer moving stage (38), and a nano-contact sensor (39) are set up; the electron microscope is equipped with an electron beam tube (32), which is directly facing the exposure area (22) of the wafer on the wafer moving stage (38), and the exposure area is divided into several writing fields; the wafer moving stage (38) is equipped with a numerical control drive device (371) for dragging it forward and backward and / or left, right and / or up and down and changing its angle; the nano-contact sensor (39) is equipped with a sensing contact (392), which is located above the wafer moving stage (38), so that the sensing contact (392) of the nano-contact sensor can contact the photosensitive adhesive layer and the in-situ alignment coordinate marks (43, 44) with a predetermined shape within it in the writing field; the in-situ alignment coordinate marks (43, 44) are pre-set on the wafer to be lithographically processed. The wafer (1) is made into a convex structure three-dimensional alignment mark, and then a photosensitive adhesive layer (2) is coated on it, so that the photosensitive adhesive layer at the position corresponding to the convex structure three-dimensional alignment mark of the wafer also produces the corresponding convex structure in-situ alignment coordinate mark (44), that is, the convex structure photosensitive adhesive layer three-dimensional alignment mark. Then the wafer (1) with the three-dimensional alignment mark is moved to the writing field area that can be exposed by the electron beam (4) through the wafer stage (38). The electron beam (4) is aligned with the position of the photosensitive adhesive layer three-dimensional alignment mark (44) to perform point exposure, and a three-dimensional mark (45) with actual deviation is generated outside the exposure point of the photosensitive adhesive layer. Then the inductive contact of the nano-contact sensor is used to contact and measure the actual coordinate values ​​of the three-dimensional alignment mark (44) and the deviated three-dimensional mark (45) on the photosensitive adhesive layer, and then calculate the correction value of the writing field exposure area, thereby controlling the electron gun to achieve longitudinal precise alignment and exposure, and achieving longitudinal precise splicing.

31. The sub-nanometer high-precision photolithography write field longitudinal stitching method according to claim 30, characterized in that: The nano-contact sensor (39) is one or a combination of two of the following: an atomic force tip sensor or a nanoscale surface work function measurement sensor.

Images