Method for lithographic exposure of a substrate, device for carrying out such a method, and computer program element
Patent Information
- Application Number
- PCT/EP2025/057928
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2025-03-24
- Publication Date
- 2026-10-01
Smart Images
Figure EP2025057928_01102026_PF_FP_ABST
Abstract
Description
[0001] EV Group E. Thallner GmbH MSP Ref: 46698 PT-WO PM / Sk / kr
[0002] Method for lithographic exposure of a substrate, device for carrying out such a method and computer program element
[0003] The present invention relates to a method for lithographic exposure of a substrate, a device for carrying out such a method and a computer program element for such a method.
[0004] Digital micromirror devices (DMDs) have been known in the art for a long time. They are optical elements consisting of a multitude of small mirrors that can be individually moved and aligned. Each mirror can be selectively controlled and oriented electrically, particularly electronically. This allows an optical system with a DMD to be used to selectively deflect a wide beam of light with spatial resolution. Usually, only two fully deflected positions are considered for each mirror. A mirror either allows the portion of the light beam that falls upon it to pass through the optical system, or it reflects that portion of the light beam so that the light is not transmitted further within the optical system. Each mirror of such a DMD can then be interpreted as a digital light switch.
[0005] Such DMDs are already used in projectors in the state of the art. DMDs are also increasingly finding application in industrial environments, such as in 3D printing, 3D surveying, and maskless lithography.
[0006] In maskless lithography, an exposure plan, created and / or stored in an analysis device and in particular free of distortion and aberration errors, especially as a virtual mask, is written directly onto the substrate using a DMD or DMDs.46698 PT-WO PM / SK © One task of maskless lithography is to expose substrates, in particular partially populated substrates, preferably fully populated substrates with defined structures, quickly, efficiently and variably.
[0007] As applications miniaturize, the semiconductor industry uses populated substrates. These substrates do not necessarily contain identical chips, but rather chips, chiplets, packages, or dies for different subtasks that are combined and, in particular, electrically connected. This can be achieved using recombined substrates or layers, also known as redistribution layers (RDLs). In the following, chips, chiplets, dies, and / or packages are understood as electronic components manufactured independently of the substrate, which can be placed onto the substrate, particularly using a pick-and-place process. For readability, they are referred to as chips.
[0008] Since the placement accuracy of pick-and-place machines is finite, chips are not positioned in their ideal positions and orientations. Therefore, each chip position and orientation is subject to alignment errors.
[0009] The alignment errors can be, for example, translation errors and / or rotation errors and / or scaling errors and / or offset.
[0010] Maskless lithography is preferably used to produce the conductive tracks between the chips in a multi-stage process involving coating, exposure, development and metallization.
[0011] This leads to the problem that, with maskless lithography, the correct conductor tracks are projected onto a defective substrate based on the existing exposure plan, potentially resulting in connections or links not being established to the desired or required extent. This leads to lithographic defects, as the produced conductor tracks may no longer make correct contact.46698 PT-WO PM / SK © Prior art discloses methods that describe measuring certain alignment marks on the substrate. The measured alignment marks then allow for a better adaptation of the virtual masks or exposure plans to the actual substrate. For example, the connecting lines, i.e., the planned paths of the conductor tracks, are adjusted in the exposure plans, particularly with regard to their length and / or orientation.
[0012] Changing the length or angle of the connecting lines can then change the resistance or capacitance of the lines and thus their complex impedances and / or create interaction between the lines (also called crosstalk).
[0013] It is therefore the object of the present invention to eliminate the disadvantages of the prior art and, in particular, to achieve an improved exposure result. Specifically, it is important to reduce the probability of a defective, exposed substrate during production.
[0014] This problem is solved by the subject matter of the dependent claims and the exemplary embodiments disclosed below. Advantageous further developments of the invention are specified in the dependent claims. The scope of the invention also includes all combinations of at least two features specified in the description, the claims, and / or the drawings. With regard to value ranges, values lying within the stated limits are also to be disclosed as limit values and may be disclosed or claimed in any combination.
[0015] According to a first aspect of the present invention, a method for lithographic exposure, in particular for mask-free lithographic exposure, of a substrate comprising functional units, such as chips, or a functional unit, is provided, comprising:
[0016] - Providing an exposure plan for a structure to be produced by exposure, when the functional units are in their target positions, 46698 PT-WO PM / SK © - Measuring the substrate with the functional units using a measuring device to determine the actual positions of the functional units, - Dividing the substrate into zones, in particular with at least one functional unit each and / or no functional unit,
[0017] - Determining a deviation between the actual and target positions for the functional units using an analysis device, - Primary adjustment of the exposure plan to the deviation between the actual and target positions with regard to the structure to be produced in the area of the functional unit or a zone, using the analysis device to provide a primarily adjusted exposure plan, - Secondary adjustment
[0018] -- of the exposure plan to the deviation between the actual position and the target position or
[0019] -- of the primary adapted exposure plan
[0020] with regard to the structure to be generated in the transition area between two zones with functional units or zone boundary area by means of the analysis device,
[0021] - Providing a customized exposure plan based on primary and secondary adjustments and
[0022] - Creating the structure by lithographic exposure according to the adapted exposure plan.
[0023] In contrast to the prior art, the exposure plan is not only adapted with regard to the structure to be generated within the functional unit, but also deliberately takes into account areas located between two adjacent and / or connecting functional units and / or in the zone boundary region. For this purpose, the structure to be generated is adjusted in the exposure plan in the transition area between two zones, particularly zones with functional units, and / or in the zone boundary region. These zones are primarily virtual, i.e., they are defined by the analysis device or by an exposure planner. If the zone is located at the outermost edge of the substrate or if only one zone is present, the secondary adjustment is made on the side(s) facing the edge or an edge of the substrate, in the zone boundary region.This means that secondary adjustment is not limited to the area between two adjacent zones, but also addresses the sides of the zone to which no other zone adjoins. The zone boundary area is preferably formed by an outermost surface of the zone, which assumes values up to 90%, preferably up to 85%, and most preferably up to 70% of the total area of the respective zone or of an average size of all zones. By combining primary and secondary adjustment, the continuity in the transition areas or in the zone boundary area in the final adjusted exposure plan can be improved, in particular in such a way that no undesirable interference effects occur in the realized structure of the manufactured, i.e., finally exposed, substrate. A connection to the potentially shifted or rotated functional unit is taken into account.
[0024] The structure to be produced is preferably a conductive track connecting at least two functional units. These are preferably fabricated using maskless lithography. Here, the structure to be produced is preferably manufactured optically, particularly using one or more DMDs. It is particularly recommended that corrections and adjustments to the exposure plan be made prior to lithography, especially in the area of the functional unit, based on measurements of the substrate. Functional units can be, for example, chips or connectors and / or a via. The zones can be of the same dimensions and / or of different dimensions. The zones are specifically adapted to the exposure plan and preferably have a polygonal shape. The measurement of the actual positions can also be performed by or accompanied by the use of an external tool.In particular, secondary adjustment involves specifying parameters for the structure to be generated that differ from those of primary adjustment. While primary adjustment, for example, only concerns the position of one end of the structure to be generated, it is preferably provided that secondary adjustment concerns the course of the structure to be generated between the functional unit area and the transition area, especially a zone boundary, and is subject to specific parameters in this regard. The relative position of several structures to be generated is considered a criterion for secondary adjustment. For example, the distance and / or the relative angle of inclination of the structures to be generated are taken into account during secondary adjustment, such as between two immediately adjacent structures to be generated.For example, primary adjustment primarily involves adapting the positions of the end of the structure to be created in the adapted exposure plan to one of the actual positions of a terminal of the functional unit.
[0025] In contrast to the prior art, the structures to be produced, especially the conductive connections, are not extrapolated from the known chip geometry to the adjacent chip geometry. Instead, gaps, particularly as quadrilateral, convex sub-zones between the natural primary orientation marks of the chips, are defined and / or taken into account. This allows the respective origins of the connections to be calculated and determined for the primary exposure plan. Individual fields, especially those produced using special, sequentially operating partial exposure units called steppers, as well as overlaps and other necessary corrections for the final exposure plan, can be considered through secondary adjustment.This allows for continuity on the substrate that otherwise—caused by manufacturing defects in the actual, populated substrate—cannot be readily guaranteed. In other words, zones can be assigned to the primarily adapted exposure plan, and corrections to the exposure plan can be made within and / or at the edges of these zones. The number and size of the zones are essentially an optimization based on the number of functional units and / or objects on the substrate and in the exposure plan, as well as the computational effort and time required. While increasing the number of zones correlates with the accuracy of the pathways, it also correlates with the necessary computational effort.Surprisingly, the efficiency of calculating the exposure plan within and at zone boundaries limits the time required to such an extent that the method can even be used in high-volume production with real-time or near-real-time exposure. In particular, the method according to the invention can produce an optimally illuminated and manufactured substrate in less than 10 minutes, preferably less than 5 minutes, and most preferably less than 2 minutes. However, external measurement of the substrate is not advantageous for this.
[0026] It has proven advantageous that this allows for an improved, i.e., faster and higher-resolution, exposure process, while simultaneously employing an improved, adapted exposure plan for the substrate. In particular, it is possible to avoid short circuits and / or faulty contacts between the chips by rerouting the conductor tracks. In other words, the layout of the virtual mask or exposure plan is optimized to ensure not only the correction of alignment errors (translation, rotation, offset, scaling) in the individual zones, but also structural and layout consistency between the zones, especially through the use of auxiliary structures.Preferably, the term analysis facility can refer to a (personal) computer, a virtual machine running on host hardware, a microcontroller, or an integrated circuit. Alternatively, the analysis facility can be a real or virtual group of computers (the technical term for a real group of computers is "cluster," the technical term for a virtual group of computers is "cloud"). Preferably, the analysis facility comprises a processing unit and a storage unit. A processing unit can comprise hardware and software elements, for example, a microprocessor or a field-programmable gate array. A storage unit or storage facility can be implemented as non-permanent working memory (e.g., random-access memory) or as permanent mass storage (e.g., hard drive, USB flash drive, SD card, lid-state disk).Furthermore, it is also conceivable that the analysis device comprises at least one server and utilizes at least one platform or a network of multiple servers that mutually support each other in carrying out the process. The analysis device preferably includes a control unit that, based on the adapted exposure plan, controls a lithographic exposure device.
[0027] The substrates can be of any shape, but are preferably circular. The diameter of the substrates is standardized, particularly in industry. For wafers, the standard diameters are 1 inch, 2 inches, 3 inches, 4 inches, 5 inches, 6 inches, 8 inches, 12 inches, and 18 inches. However, the process can, in principle, handle any substrate, regardless of its diameter. Rectangular panels of any size are also considered substrates.
[0028] Preferably, primary and secondary adjustments are repeated iteratively. This allows for further optimization of the adjusted exposure plan. Preferably, the iteration is stopped when the adjustment converges or an optimum adjustment is reached.
[0029] Preferably, the deviation of the target position from the actual position is provided as the primary deviation vector and / or a deviation of the primarily adjusted exposure plan from the exposure plan is provided as a secondary deviation vector. This simplifies data handling for the analysis device. Furthermore, it allows the user to visualize the deviation, enabling them, for example, to take additional measures in the adjustment process if the deviations are too large, or to terminate the adjustment process if it becomes apparent that a satisfactory result cannot be expected.
[0030] In particular, it is intended that a primary alignment mark on the functional unit is detected and / or defined for primary alignment, especially in a machine reference system. The primary alignment marks are, in particular, the result of a measurement of the mounted substrate. After the measurement, the primary alignment marks can be defined. These are linked, in particular, to actual, real-world characteristics, especially of the functional unit. For example, the actual position of a corner of a functional unit is used as a primary alignment mark. The position and orientation of a respective chip can also be determined by defining the center point and the angular position, so that, in particular, the corner points of the chip are calculated for the known chip geometry. Both methods of detecting the actual position of a functional unit are to be considered equivalent.
[0031] In a less preferred embodiment of the method, the measurement of a substrate at least partially equipped with functional units can be carried out in an external measuring device, particularly by transmitting the positions of the functional units in a machine reference system in a machine-readable list, especially a structured file. In this embodiment of the device, a measuring device is optional.
[0032] In a preferred embodiment of the method, each substrate is measured individually, and the mask is optimized, corrected, and exposed for a timeframe acceptable in high-volume production. In another embodiment, a general correction of the mask with primary and secondary adjustments can be performed if little or no individual measurement data is available and not desired by the user.
[0033] However, it is an essential aspect of the present invention that the acceptable processing and computing time for a substrate is less than 10 minutes, preferably less than 7 minutes, particularly preferably less than 5 minutes, and in the optimal case less than one minute.
[0034] The primary alignment markings preferably serve to define the geometry of the discrete zones containing the chips. In this way, the chips and their surroundings can be represented as polygons, preferably quadrilaterals, in the analysis device, with the vertices, preferably the alignment structures, representing the actual position of the chips and their surroundings. From this, the analysis device calculates the actual position of the required electrical contacts. Preferably, the primary alignment marking is determined after the substrate has been measured.
[0035] To measure the substrate, it is attached to a substrate holder and measured, in particular, with a collimating microscope. The substrate holders have fixings. These fixings serve to hold the substrates in place. The fixings can be...
[0036] - Mechanical fixings, especially clamps, or
[0037] - Vacuum fixings, in particular with individually controllable vacuum paths or with interconnected vacuum paths, or
[0038] - Electrical fixings, especially electrostatic fixings, or
[0039] - Magnetic fixings, or
[0040] - Adhesive fixations, especially gel pack fixations, or
[0041] - Fixations with adhesive, and in particular controllable, surfaces. The fixations are, in particular, electronically controllable. Vacuum fixation is the preferred fixation method. The vacuum fixation preferably consists of several vacuum channels that emerge from the surface of the substrate holder. The vacuum channels are preferably individually controllable. In a more technically feasible application, several vacuum channels are combined into vacuum channel segments that can be individually controllable and therefore evacuated or flooded. Each vacuum segment, however, is independent of the other vacuum segments. This allows for the construction of individually controllable vacuum segments. The vacuum segments are preferably designed in a ring shape. This enables targeted, radially symmetrical fixation and / or release of a substrate from the substrate holder, particularly from the inside out.
[0042] In particular, virtual secondary alignment markers are defined in the transition area and / or the zone boundary area for secondary alignment. This defines additional auxiliary structures in the exposure plan in the transition area between two zones and / or in the zone boundary area. Thus, alignment is preferably achieved using two types of alignment markers: the primary alignment marker serves to define the orientation and position of the respective chip or functional unit on the substrate and / or to describe the substrate into individual zones that are connected to each other. The secondary alignment marker serves to align the virtual connection and contact points of the electrical conductors in the area between two functional units or chips.
[0043] In particular, virtual, secondary alignment markers are added to the respective spaces between primary alignment markers of adjacent zones, which are, for example, shaped as convex quadrilaterals, in order to ensure the continuity of the lines not through extrapolation, which is often faulty, but through interpolation between the primary and secondary alignment markers. This applies especially to outer zones.Since the exposure plan is known, objects, secondary alignment markers and / or virtual connections can be added to the exposure plan, especially at zone boundaries, which enable an optimization of the adapted exposure plan, since an adapted exposure plan is calculated from the measured values, especially the primary alignment marker, and from the information known from the exposure plan, especially in the area of the secondary alignment marker.
[0044] It is particularly preferred that the virtual secondary alignment mark has an extent in at least one direction that is smaller than the resolving power of the measuring device and / or the lithography apparatus. If the extent of the virtual alignment mask is below the resolution limit of the maskless lithography apparatus, the secondary alignment mark can be used to adjust the exposure plan or the virtual mask for distortion compensation, particularly without its size interfering with the adjustment of the exposure plan. In particular, the secondary alignment mark is then not produced in a way that interferes with the exposure of the substrate. In other words, the secondary alignment mark remains undetectable on the exposed and realized substrate. This is particularly advantageous if the secondary alignment mark is implemented as an interruption in the structure to be produced.This is then not realized in the exposed substrate. Accordingly, the size of the primary and / or secondary alignment mark, especially as an interrupter, can be below the process-related resolution limit of maskless lithography.
[0045] The process-related resolution limit of maskless lithography and the maskless lithography device is limited by the resolution of the device, by the radiation source, by the material (photoresist, its sensitivity) and the resolution limit of the exposure optics used.
[0046] Thus, for example, interrupts used as secondary alignment markers are not mapped onto the substrate. They are only used for determining the adjusted exposure plan. The auxiliary structures of the additional lines required for pattern continuity can also be mapped onto the adjusted exposure plan in such a way that they are written onto the substrate. Therefore, all auxiliary structures can be represented on the adjusted exposure plan. Since the auxiliary structures do not need to be removed from the adjusted exposure plan in a further process step, the optimization process is faster because a recalculation of the corrected mask is unnecessary.46698 PT-WO PM / SK © For example, the exposure of a substrate using maskless lithography is prepared as follows:
[0047] The positions of the locally confined zones (dies, chips, etc.) are defined in the nominal, ideal original exposure plan in the analysis setup. Optimization is initiated by measuring the actual positions, assigning the confined zones to the measured values, and determining the correction vectors.
[0048] Auxiliary structures, such as zones, primary alignment markers and / or secondary alignment markers, are created in the form of lines or polygons or interrupters, whereby the line width of the newly defined auxiliary structures, except for the intentionally mappable lines, is below the resolution limit of the exposure device.
[0049] For example, the following logical operations can be performed on the exposure plan to insert the auxiliary structures:
[0050] - Subtraction (XOR): This creates a break in a continuous mask structure in the transition or edge region. The break in the previously existing structure for the desired pattern lies below the resolution limit, so it is not ultimately reproduced on the substrate during lithography. The effect of this break is that the alignment and optimization of adjacent zones can be performed. - Addition (AND): This creates continuity, particularly using a writable line element or polygon, between two breaks.
[0051] To further optimize the exposure plan, it is supplemented with virtual secondary alignment markers in the form of lines or points, which are used in particular to define the boundary conditions for mask continuity. The size of the lines or points is below the resolution limit of the lithography device, so that they do not appear on the substrate as written objects.
[0052] In particular, the virtual secondary alignment markers are intended to form a grid or be positioned on a grid. This grid can consist of zones of equal or different sizes. It is also conceivable that the zones differ in their geometry. The free selection of the virtual secondary alignment markers allows their position to be changed, further optimizing the adjustment of the exposure plan.
[0053] Preferably, the secondary adjustment is performed after the primary adjustment. This establishes a boundary condition with the primary adjustment that is crucial for the functionality of the exposed substrate.
[0054] In particular, it is intended that zone definition, primary adjustment, and / or secondary adjustment will be implemented using empirical data and / or machine learning. This allows for the advantageous use of relevant empirical data during the adjustment process. For example, it is beneficial to provide corresponding test datasets that compare zone selection, primary adjustment, and secondary adjustment with the actually generated structures and their physical properties.
[0055] The considerations listed below are examples of how to provide a customized exposure plan:
[0056] Two adjacent zones each define a zone boundary. Electrical contacts, representing secondary alignment marks, are located on the zone boundary.
[0057] The secondary alignment markers can be implemented as interrupters and connectors (abbreviated as interrupters) or shown in the exposure plan to be processed.46698 PT-WO PM / SK © They are located on the respective zone boundary, for example at an intersection of the zone boundary with an electrical conductor that connects a functional unit, in particular a chip, from one zone to the surroundings. In other words, the optimization task is to connect a first zone to the second, directly adjacent zone with an electrical conductor.
[0058] For this purpose, the primary alignment marks are recorded and defined, the edges or zone boundary are defined, and a total of two interrupters are identified that must be connected. It has been found that, due to alignment errors, the first interrupter of the first zone and the second interrupter of the second zone are not always perfectly aligned. Specifically, both the primary alignment mark and the interrupters on the zone boundary, which in this embodiment define the secondary alignment mark, are iteratively optimized in the analysis device so that the first interrupter of the first zone and the second interrupter of the second zone are perfectly aligned. In this process, it is specifically permissible for the electrical conductor to have a kink.
[0059] The procedure also provides for the insertion of an additional auxiliary line between the circuit breakers if direct optimization fails, i.e., if the alignment of the first breaker in the first zone with the breaker in the second zone cannot be achieved. This ensures the continuity of the electrical lines even in the case of significant misalignment.
[0060] This type of optimization is performed for each zone and for each breaker on a substrate until all chips are connected with all necessary connections, so that a customized exposure plan is completed.
[0061] The adapted virtual mask is then written to the substrate using maskless lithography.46698 PT-WO PM / SK © In a further preferred embodiment, the chips and their surroundings can be represented as polygons, preferably quadrilaterals, in the exposure plan, with the vertices, which preferably represent the primary alignment marker, indicating the actual position of the chips and their surroundings. From this, the analysis device calculates the actual position of the required electrical contacts.
[0062] Two adjacent zones each define an edge or zone boundary. Electrical contacts, representing the secondary alignment mark, are preferably located on the zone boundary.
[0063] The secondary alignment marks can be understood as breakers and connectors (breakers for short). They are located on the respective zone boundary, specifically at the intersection of the zone boundary with an electrical conductor that connects a chip from a zone to its surroundings.
[0064] In other words, the optimization task is to optimally connect a first zone, which is spaced apart from the directly adjacent second zone, to the second zone using an electrical conductor.
[0065] To bridge the gap between the boundary of the first zone and the adjacent, but spaced-apart, boundary of the second zone, an additional auxiliary structure (line) is inserted between the breakers. This line then lies between the zone boundaries in the transition area. This ensures the continuity of the electrical lines even in the event of significant misalignment.
[0066] Thus, continuous patterns intended in the original exposure plan are preferably interrupted by adding auxiliary structures, especially breakers, in order to be reconnected in an optimization process, particularly with additional lines. Alternatively, after the interruption, the optimized positions are determined and pattern continuity is restored by reconnecting the breakers.46698 PT-WO PM / SK © According to another aspect, a procedure for optimizing an exposure plan for maskless lithography is provided, consisting of the following steps, in particular with the following sequence:
[0067] In a first procedural step, an ideal, nominal mask, i.e. an original exposure plan, is loaded into the analysis device.
[0068] In a second process step, a substrate to be exposed according to the exposure plan is attached to a substrate holder and loaded into the maskless exposure device.
[0069] In a third process step, primary alignment marks, i.e., reference points and / or structures and / or adjustment marks, are detected on the substrate, in particular using at least one alignment microscope. The measured values are acquired in a machine reference coordinate system. The measuring device is integrated into the exposure unit.
[0070] In a fourth process step, the primary deviation vectors to the corresponding reference values of the ideal original exposure plan are calculated from the recorded measured values.
[0071] In a fifth process step, the correction of the exposure plan into an adapted exposure plan is carried out, particularly iteratively, whereby the detected deviations of the structures are used to correct the translation and rotation and distortion and scaling on the basis of the primary deviation vectors.
[0072] In a sixth, particularly iterative, process step, the layout and structural consistency between the locally separated zones is checked and, if necessary, achieved by adding secondary alignment markers. This results in the creation of the adapted exposure plan.
[0073] The fifth and sixth process steps can be performed iteratively one after the other until an optimum is reached.46698 PT-WO PM / SK © In a seventh process step, the adapted exposure plan is mapped onto the substrate using the maskless exposure device, i.e., the substrate is exposed.
[0074] In an eighth process step, the exposed substrate is unloaded from the device.
[0075] The processes described here are carried out particularly in automated devices, especially as recipes. Recipes are optimized sets of parameter values that are functionally or procedurally related. The use of recipes ensures the reproducibility of production processes.
[0076] According to a second aspect, a procedure for optimizing an exposure plan for maskless lithography is provided, comprising the following steps, in particular the following sequence:
[0077] In a first procedural step, an ideal, nominal mask, i.e. an original exposure plan, is loaded into the analysis device.
[0078] In a second process step, the ideal, nominal mask is equipped with secondary alignment marks in individual zones according to the known arrangement of all elements on the mask, thus calculating a customized exposure plan. The secondary alignment marks contain the points at which the individual zones can be virtually moved and / or rotated relative to each other during alignment.
[0079] In a third process step, a substrate to be exposed according to the exposure plan is attached to a substrate holder and loaded into the maskless exposure device.
[0080] In a fourth process step, alignment marks, i.e., reference points and / or structures and / or adjustment marks on the substrate, are detected, in particular using at least one alignment microscope. The acquisition of the measured values is carried out in a machine reference coordinate system. The measuring device is integrated into the exposure unit.
[0081] In a fourth process step, the primary deviation vectors to the corresponding target positions of the exposure plan are calculated from the recorded measured values.
[0082] In a fifth process step, the correction of the exposure plan into an adapted exposure plan is carried out, particularly iteratively, whereby the detected deviations of the structures are used to correct the translation and rotation and distortion and scaling on the basis of the primary deviation vectors.
[0083] Layout and structural continuity can be ensured using secondary alignment markers.
[0084] The fourth and fifth process steps can be used iteratively one after the other until an optimum is reached.
[0085] In a sixth process step, the adapted exposure plan is mapped onto the substrate using the maskless exposure device, i.e., the substrate is exposed.
[0086] In a seventh process step, the exposed substrate is unloaded from the device.
[0087] Another object of the present invention is a device for carrying out a method according to the invention, comprising
[0088] - Measuring device
[0089] - Analysis facility and
[0090] - Device for lithographic exposure, in particular an exposure device. All advantages and properties described for the method apply analogously to the device and vice versa. 46698 PT-WO PM / SK © Preferably, the device for lithographic exposure has a micromirror element. This makes the method advantageously usable for maskless lithographic exposure.
[0091] According to a further aspect of the invention, it is advantageous that the maskless exposure device includes the necessary measuring instruments, such as an alignment microscope, and that the control and / or regulation of the exposure device performs the necessary mask optimization independently before the exposure process, particularly via software. Thus, optimized exposure (adaptive patterning) or optimized exposure with a modified pattern (rerouting) can be carried out in the device as an application of the method.
[0092] For further maskless exposure steps of the substrate, the acquired measurements can be saved, and further ideal masks can be optimized into corrected masks according to the procedure. In this way, the third process step, the measurement of the structures on the substrate, can be omitted, since the measurements are already available.
[0093] Another aspect of the present invention is a computer program element with instructions that, when executed on data processing equipment in a data processing environment, are configured to carry out the method according to the invention, particularly in an apparatus according to the invention. All advantages and properties described for the method and the apparatus apply analogously to the computer program element and vice versa.
[0094] Further advantages, features, and details of the invention will become apparent from the following description of preferred embodiments and from the drawings. These show:
[0095] Figs. 1a-1b State after a process step of the process according to the invention, 46698 PT-WO PM / SK © Figs. 2a-d Schematic illustrations of the mask drawing and associated lithography on the substrate
[0096] In the figures, identical components or components with the same function are marked with the same reference symbols.
[0097] Fig. 1a shows a schematic sketch of an exposure plan in the form of a virtual, corrected mask 1 with chips 2, i.e., the functional units. The corners of the chips 2 serve as natural primary alignment marks 3, so that alignment errors such as rotations, displacements, etc., can be taken into account using these primary alignment marks 3. Furthermore, a subdivision into virtual zones is shown by the dotted line. Some zones are numbered for clarity (10, 20, 30, 40). These are separated from each other by transition areas 15, in particular by zone boundaries 7. The additional, in particular virtual, secondary alignment marks 4 are arranged, especially at transition areas 15 between zones or at zone boundary areas 16.They serve to provide additional points in transition zone 15 or in zone boundary zone 16 for the continuity of invoices as well as for correction invoices.
[0098] The structures 6 to be generated, in the form of electrical conductors 6, are represented by respective virtual interrupters 5 in the transition region 15 or zone boundary region 16, so that the conductors can be modified for the corrected model: Preferably, they are changed with respect to an angle and / or with respect to their length to adapt them to the exposure plan, i.e., they can be shortened and / or lengthened. This advantageously ensures the desired continuity in the exposure plan, in particular of the electrical conductors in the transition region 15 or in the zone boundary region 16. Preferably, the primary alignment marks 3 or reference positions of the chips 2 near the virtual alignment marks 4 can be corrected in the x- and / or y-direction by at least one unit of length. This unit of length is below the resolution limit of the device. For example, the unit of length can be 1 nm.The natural primary alignment markers 3 and the virtual secondary alignment markers 4 are preferably represented in a mask-related coordinate system, particularly in a Cartesian coordinate system with the same units of length. The number of primary alignment markers 3 and / or secondary alignment markers 4 is preferably determined by specifications of the exposure plan, for example, its complexity. There can be any number of possible alignment markers 3, 4.
[0099] The preferred cell width and height lie between one and one million units of length. For practical calculations, a cell size of approximately 1 pm x 1 pm is preferred when the functional unit comprises a chip. For plasmonic applications, the cell size is on the order of 1 nm x 1 nm. The maximum size is limited by the chip or substrate size and can be 1 e⁶ micrometers in width and 1 e⁶ micrometers in height, which can be a suitable order of magnitude for panels.
[0100] Fig. 1b shows an enlarged detail view of Fig. 1a. For example, a zone boundary 7 is placed on an outer edge of a functional unit 2, depicted from zone 20, so that a correction of the contact 6 can be made at a transition area 15 thus created. In this way, both the variance in the position of the contact point and that of the angles can be corrected accordingly as possible errors.
[0101] Figures 2a and 2c show two schematic sections of a structure 6' and 6", respectively, to be generated, in particular in the form of a conductor track, on the virtual mask with the respective interrupters 5' and 5", respectively. The geometry and dimensions of the interrupters 5' and 5" are selected such that they cannot be represented on the substrate. Accordingly, Figures 2b and 2d schematically show the respective written, continuous conductor tracks 8 and 8'. 46698 PT-WO PM / SK ©
[0102] Reference symbol list:
[0103] I adapted exposure plan
[0104] 2 Chip
[0105] 3 primary alignment marks
[0106] 4 virtual secondary alignment marks 5, 5', 5" interrupter
[0107] 6, 6', 6" structure to be generated
[0108] 7 Zone border
[0109] 10, 20, 30, 40 zones (example)
[0110] II. Area of the functional unit
[0111] 8, 8' written conductor track on substrate 15 transition area
[0112] 16 Zone boundary area
Claims
46698 PT-WO PM / SK © Claims 1. A method for lithographic exposure, in particular for mask-free lithographic coating, of a substrate having functional units, such as chips, or a functional unit, comprising: - Providing an exposure plan for a structure to be produced by exposure (6, 6', 6"), when the functional units are in their intended positions or the functional unit is in its intended position, - Measurement of the substrate with the functional units using a measuring device to determine the actual positions of the functional units or the functional unit, - Dividing the substrate into zones, in particular each with at least one functional unit, - Determining the deviation between the actual positions and the target positions for the functional units using an analysis device, - Primary adjustment of the exposure plan to the deviation between the actual position and the target position with regard to the structure to be produced in the area (11) of the functional unit or a zone, using the analysis device to provide a primarily adjusted exposure plan, - Secondary adaptation -- of the exposure plan to the deviation between the actual position and the target position or -- of the primary adapted exposure plan with regard to the structure to be generated in a transition area (15) between two zones, in particular with functional units or a zone boundary area (16), using the analysis device, 46698 PT-WO PM / SK © - providing an adapted exposure plan (1) based on the primary adaptation and the secondary adaptation and - Creating the structure by lithographic exposure according to the adapted exposure plan (1).
2. Method according to claim 1, wherein primary fitting and secondary fitting are repeated iteratively.
3. Method according to one of the preceding claims, wherein the deviation of the target position from the actual position is provided as the primary deviation vector and / or a deviation of the primarily adapted exposure plan from the exposure plan is provided as the secondary deviation vector.
4. Method according to one of the preceding claims, wherein for the primary adjustment a primary alignment mark (3) is detected and / or set on the functional unit, in particular in a machine reference system.
5. Method according to claim 4, wherein the primary alignment mark is determined after the substrate has been measured.
6. Method according to one of the preceding claims, wherein virtual secondary alignment markers (5) are defined in the transition area (15) or in the zone boundary area (16) for secondary adjustment.
7. A method according to any one of the preceding claims, wherein the secondary alignment mark (5) comprises a break in the structure to be produced. 46698 PT-WO PM / SK © 8. A method according to claim 6 or 7, wherein the virtual alignment mark (5) has an extent in at least one direction that is smaller than the resolving power of a measuring device or lithographic exposure device.
9. Method according to one of the preceding claims, wherein the virtual alignment marks (5) form a grid or lie on a grid.
10. Method according to one of the preceding claims, wherein the secondary adjustment is performed after the primary adjustment.
11. Method according to one of the preceding claims, wherein a definition of zones, a primary adjustment and / or a secondary adjustment is realized through experience and / or machine learning.
12. Device for carrying out a method according to one of the preceding claims, comprising: - Measuring device - Analysis facility and - Equipment for lithographic exposure.
13. Device according to claim 12, wherein the device for lithographic exposure comprises a micromirror element.
14. Computer program element with instructions that, when executed on data processing equipment of a data processing environment, are configured to execute the method according to any one of claims 1 to 11, in particular in a device according to any one of claims 12 and 13.