DE102021113189A1 - Method for producing a three-dimensional target structure in a lithographic material using a laser lithography device - Google Patents

Abstract

The invention relates to a method for producing a three-dimensional target structure (44) in a lithographic material (22) using a laser lithography device (10), a substrate (40) with lithographic material arranged thereon being provided, with an interface (54) between lithographic material and substrate is localized, with the target structure being defined in that a focus area (28) of a writing laser beam (14) is shifted by means of an optical device (16) within a writing area (34) of a scanning surface (36) in accordance with predetermined writing instructions, wherein in the Focus area of the write laser beam, a write exposure dose is radiated into the lithographic material and a structure area (46) is defined, with a focus area of a calibration laser beam using the optical device sequentially to a plurality of test positions within to localize the interface between substrate and lithographic material b of the writing area of the scanning surface, a test exposure dose being radiated into the lithographic material at each test position and position data of the interface (54) being determined from a response of the lithographic material and/or the substrate to the test exposure dose. The invention also relates to a laser lithography apparatus.

Description

The invention relates to a method for producing a three-dimensional target structure in a lithography material using a laser lithography device. The invention also relates to a laser lithography device adapted and designed for the method.

The techniques mentioned are used in particular in the production of micro- or nanostructures in areas in which high precision and at the same time freedom of design for the structure to be produced are desired. In such laser lithography methods, a structure is usually written by first providing a substrate with lithography material arranged thereon and then irradiating an exposure dose into the lithographic material in a focus area of a writing laser beam, thereby locally defining a structure area, for example by Lithography material is locally cured or polymerized. A three-dimensional overall structure can then be produced by shifting the focus area in the lithography material. For this purpose, the focus area of the writing laser beam can be controlled by means of an optics device within a scanning area with the precision required for structuring. Such a laser lithography method is, for example, from DE 10 2017 110 241 A1 known.

In order to be able to produce structures with high precision using such a laser lithography method, it is necessary to create a relationship that is as precise as possible between the focus area or the scanning area of the writing laser beam and a substrate surface on which the structure is to be built. In particular, it is important to determine a position of the substrate surface relative to the focus area or the scanning area as precisely as possible. For this purpose, it is known in principle to localize an interface between substrate and lithography material and thus to determine a focus before actually writing the structure.

From the US7893410B2 For example, a method is known in which the substrate is moved laterally to the optical axis of a writing laser beam by means of a positioning device and a position of the interface between substrate and lithographic material relative to the focal area of a writing laser beam is determined at a plurality of positions. Such a method makes it possible, for example, to detect a tilting of the substrate relative to the scanning area.

The object of the invention is to produce a three-dimensional structure with high precision in a lithographic material.

This object is achieved by a method according to claim 1. This is a laser lithography method, in particular so-called direct laser writing, using a laser lithography device in a volume of lithography material or in a volume filled with lithography material.

According to the method, a substrate with lithographic material arranged thereon is first provided. The substrate can be displaced in particular by means of a positioning device of the laser lithography device designed for this purpose. In particular, the substrate can be displaced in all three spatial directions (x, y, z) by means of the positioning device, more particularly also tiltable about at least one axis of inclination parallel to a substrate surface (x-y plane).

According to the method, a target structure is written or defined in the lithographic material by sequentially defining a plurality of structural regions (also referred to as “voxels” below) that complement each other overall to form the target structure (i.e. with the laser lithography device in the lithographic material. is written"). To write the structure areas and thus the target structure, a focus area of a writing laser beam is shifted in a controlled manner by means of an optics device within a writing area of a scan area defined by the optics device, in particular laterally to the optical axis of the writing laser beam. In particular, the focal region traverses a scan manifold within the scan area. In the simple case, the scan manifold can be a scan curve, but it can also be made more complex. For this purpose, the writing laser beam can be controlled by means of the optics device within the writing area with the precision required for the purpose of structuring. For this purpose, the optics device can comprise beam shaping, beam guiding and/or beam steering devices for the laser beam that are fundamentally known from the prior art. In principle, it is also conceivable that, in order to define the target structure, the substrate with the lithography material is additionally displaced in a controlled manner relative to the writing laser beam by means of the positioning device.

A write exposure dose is radiated into the lithographic material in the focus area of the write laser beam, with the lithographic material being locally modified, in particular using multi-photon absorption, and thus a structural area being generated or written becomes. In this respect, the lithography material is structured locally. In particular, the lithographic material is chemically and/or physically changed, for example cured or polymerized, by the irradiation of the writing exposure dose. The exposure dose is in particular a volume dose of radiant energy. The size of the changed structural area (“voxels”) in the lithography material depends on the writing exposure dose. The spatial extent of the respective structure region or voxel, in particular a structure height, can thus be changed by varying the writing exposure dose.

The displacement of the writing laser beam by means of the optics device and the local irradiation of the writing exposure dose takes place in accordance with specified or specifiable writing instructions. In particular, the write instructions can be stored or can be stored in a control device of the laser lithography device. To this extent, the method includes in particular a step in which the writing instructions are specified, in particular before and/or during the actual writing. The writing instructions preferably include control instructions, on the basis of which the optics devices, in particular a scanning device and/or a beam shaping device of the optics device, can be controlled. The writing instructions also include, in particular, exposure instructions which specify a location-dependent write exposure dose to be irradiated for the scan variety.

According to the method, an interface between the lithography material and the substrate is localized, in particular before the structure is actually written. In particular, a position of the interface relative to the scanning area is determined. It is also conceivable that the interface is localized additionally or exclusively during the writing of the structure, “online” so to speak.

In order to localize the boundary surface, it is proposed to shift a focus area of a calibration laser beam, in particular the focus area of the writing laser beam, sequentially to a plurality of test positions within the writing area of the scanning surface laterally to the optical axis and to locally inject a test exposure dose into the irradiate lithographic material. From a response of the lithographic material and/or the substrate to this test exposure dose, positional data of the interface are then determined, in particular with the aid of a computer. In particular, a position of the interface relative to the focus area of the writing laser beam is determined for a plurality of positions within the scanning area. It is also possible for an overall position of the interface relative to the scanning area to be determined from the position data determined at the individual test positions.

According to the method, the focus area of the calibration laser beam is shifted to the test positions by means of the same optical device by means of which the writing laser beam is also shifted for actually defining the structure. In this respect, the calibration laser beam in particular passes through that beam guiding device and/or scanning device of the optics device, by means of which the write laser beam is deflected to define the structural regions within the scanning area. The displacement of the calibration laser beam to the test positions preferably takes place with the substrate stationary laterally to the optical axis, ie in the x-y plane. In other words, the test positions are not approached by moving the substrate laterally to the optical axis. In particular, the test positions are distributed over the writing area of the scanning surface.

Such a method not only makes it possible to detect deviations of the interface or the substrate surface from the ideal shape of a completely flat surface (e.g. a curvature or local unevenness of the substrate or a tilting of the substrate in relation to the scanning surface), but also deviations in the scanning surface from the ideal shape of a plane (e.g. a curvature of the scan surface or a tilting of the scan surface in relation to the substrate). It has been recognized that the scanning surface can also deviate from the ideal shape of a plane that is plane-parallel to the substrate surface, for example due to errors in the optics device, which can lead to structural errors when writing the target structure. With the present method, it is now possible to detect such a location-dependent change in the position of the focus area relative to the substrate within the scanning area caused by the optics device and thus to determine a location-dependent focus with comparatively high accuracy. A writing process can then be adjusted accordingly on the basis of the determined position data in order to compensate for deviations from an ideal system and thus to generate structures with particularly high dimensional accuracy.

It can be particularly advantageous if the writing area is sequentially displaced and positioned laterally to the optical axis relative to the substrate and the interface between the substrate and the lithographic material is localized in each case in the writing area. In this respect, the interface is localized in particular at a first position of the writing area relative to the substrate, as explained above (i.e. a plurality of test positions approached within the writing area), the writing area is then shifted laterally to the optical axis relative to the substrate to a new position and the interface is localized again there (i.e. a plurality of test positions are also approached within the newly positioned writing area). Such a method makes it possible, in particular, to be able to distinguish between a deviation of the substrate from its ideal shape and a deviation of the scan area from its ideal shape, and thus to be able to adapt a writing process particularly precisely. In addition, a curvature of the substrate can be detected particularly precisely in this way. The writing area can be relocated, for example, by relocating the substrate and/or by changing the optics device, in particular relocating an objective module of the optics device.

An advantageous embodiment of the method is that an optical signal is detected in a spatially resolved manner to determine the position data. In particular, it can be advantageous to detect a detection radiation emitted by the lithography material and/or the substrate as a response to the test exposure dose in a spatially resolved manner by means of an optical measuring device. The detection radiation can in particular be radiation backscattered by the lithography material and/or the substrate or generated by fluorescence. It is conceivable, for example, that radiation reflected at the interface is detected. The position data can then be determined, in particular, in that detection data collected by the optical measuring device are further processed computationally, for example by means of a control device of the laser lithography device set up for this purpose. The radiation generated by fluorescence can be, for example, fluorescence radiation generated by non-linear excitation (non-linear fluorescence).

In particular, the position data represent a focus position of the substrate along the optical axis of the calibration laser beam, in which the focus area of the calibration laser beam lies in the interface between the lithography material and the substrate. In this respect, the position data represent in particular a relative position of the substrate and focus area, at which the scan area intersects the interface.

For a particularly precise position determination, it can be advantageous if a plurality of laser pulses are irradiated into the lithographic material at each test position and, during this time, the substrate with the lithographic material is moved along the optical axis of the calibration laser beam, in particular along a main irradiation direction (z-direction). becomes. In this respect, a response of the lithographic material and/or the substrate to the test exposure dose can be detected at each test position for a plurality of z positions of the substrate and in this way a dependence of the response of the lithographic material and/or the substrate on a position of the substrate be determined (z-sweep). In principle, it is also conceivable that the focus area is shifted along the main direction of irradiation. From the measurement data obtained from this, for example reflection or fluorescence data of an optical measuring device, the position data can then be determined, in particular by computation. For example, the measurement data can be recorded in a measurement curve and a simulated response of an ideal system can be fitted for evaluation. In this way, the position of the boundary surface can be determined particularly precisely relative to the focus area. The laser pulses are, in particular, modulated laser pulses generated by a modulation device, which in turn consist of many intrinsic pulses (e.g. fs laser pulses). For example, a pulse duration can be 1 μs or longer. The laser pulses are therefore in particular not pulses intrinsically generated by the laser source.

In order to avoid structure artifacts caused by the calibration measurements, it is preferred if the lithographic material is not changed by the irradiation of the test exposure dose within the scope of the calibration measurements. For this purpose, it can be particularly advantageous if the total test exposure dose irradiated by the calibration laser beam for each test position is chosen to be so low that no structuring occurs in the lithographic material. In particular, a laser intensity is selected which is below the threshold value at which appreciable polymerization of the lithographic material takes place (polymerization threshold). This makes it possible to carry out the calibration measurements several times without negatively influencing a later writing result.

In order to avoid photobleaching in the lithographic material during the calibration measurements, it can also be advantageous if the focus area of the calibration laser beam is wobbled laterally, ie orthogonally to an irradiation direction, when irradiating the test exposure dose. In particular, wobbling refers to an oscillating movement perpendicular to the optical axis.

The calibration laser beam can be a laser beam that is separate from the writing laser beam. Then the laser litho graphy device include in particular a second laser source for emitting a calibration laser beam. Such an embodiment with a separate calibration laser beam makes it possible to localize the boundary surface “online”, so to speak, even during the actual definition of the structure by the writing laser beam. In this case it is advantageous if the calibration laser beam is calibrated to the writing laser beam. For this purpose it is conceivable, for example, that a response of the lithographic material and/or the substrate to a test exposure dose of the writing laser beam and the calibration laser beam is detected one after the other, in particular a backscatter or fluorescence signal. A correlation between the writing laser beam and the calibration laser beam can then be determined from a comparison of the detected signals. It is also conceivable that a writing result of the writing laser beam, in particular a structure defined with the writing laser beam, is correlated with a measurement result of the calibration laser beam.

As part of an alternative embodiment, it is also possible for the write laser beam itself to be used as the calibration laser beam. In this respect, the writing laser beam is first shifted to the test positions by means of the optics device and a test exposure dose is radiated in there locally before the actual structuring of the lithographic material takes place using the writing laser beam. Such a design enables an intrinsic calibration. In particular, an effective surface can thus be measured.

The optics device and/or at least one writing instruction is preferably changed as a function of the determined position data. In particular, the writing process is adapted as a function of a determined position of the interface relative to the scanning area. In principle, this can include the adaptation of hardware (e.g. an adjustment of the optics of the optics device) and/or software (e.g. an arithmetic adaptation of write data sets, see below). In particular, the laser lithography device is then controlled by means of the correspondingly adapted optics device or on the basis of the adapted writing instructions in order to write the target structure.

An advantageous embodiment of the method can provide, for example, that a local exposure dose is adjusted as a function of the determined position data. In particular, depending on the determined position data, a local write exposure dose is changed at least for a subset, in particular only for a subset, of the scan points along a scan manifold to be traversed by the write laser beam. In other words, a writing exposure dose is adapted as a function of the location as a function of the determined position data.

Alternatively or additionally, a configuration of the scan area can also be changed depending on the determined position data. In particular, the scanning surface can be aligned relative to the substrate as a function of the determined position data by changing the optical device, for example straightened by beam shaping and/or tilted relative to the substrate. The scanning area is preferably changed as a function of the determined position data in such a way that the scanning area is aligned parallel to a substrate surface of the substrate.

Alternatively or additionally, it is also possible for a position and/or position of the substrate to be changed as a function of the determined position data of the interface, in particular by means of a positioning device designed for this purpose. For example, it is conceivable that the substrate is aligned horizontally, in particular parallel to the scanning area.

In particular, the write instructions can be stored or can be stored in at least one write data record. The at least one write data record can preferably be stored or can be stored in a memory device of the control device of the laser lithography device. Depending on the determined position data of the interface, at least one corrected write data set can then be determined, in particular from the at least one write data set, on the basis of which the laser lithography device is controlled in order to produce the target structure. Such a method can be automated and thus enables a simple and user-friendly calibration. For example, an “ideal write data record” can first be provided, which contains write instructions for an ideal system in which the boundary surface and the scan surface are oriented plane-parallel to one another. This “ideal write data set” can then be adjusted by computation depending on the determined position data in order to compensate for deviations of the real system from the ideal system (e.g. a tilting of the substrate relative to the scan surface and/or a curvature of the scan surface, etc.).

The at least one write data record can in particular include control data for controlling the optics device. The at least one write data record preferably includes control data for controlling a scanning device and/or a beam shaping device of the optics device. In this respect, the control data, in particular for the writing laser beam, can specify a scan course within the scan area and/or a beam shape (e.g. a suitable pulse shape). For example, it can be advantageous, particularly in an embodiment of the method in which the write laser beam is used as the calibration laser beam, if the calibration laser beam is changed by beam shaping, for example tilting the focus by half-side shading. This enables a particularly precise measurement.

The at least one write data record can in particular also include write exposure data which represent a local exposure dose for each scan point along a scan manifold of the write laser beam through the lithographic material. In this respect, the writing exposure data specify the exposure dose with which radiation is to be applied at a specific position of the scan manifold. The writing exposure data can be provided in particular by providing a structure data record (e.g. CAD data) that represents the target structure to be generated or storing it in a control device and then using the computer to determine the writing exposure data, for example by means of a device set up for this purpose Control device of the laser lithography device. According to an advantageous development, the writing exposure data can be present in the form of gray scale image data representing the target structure, different gray scales defining different structure heights. To this extent, the writing exposure data can be visualized as greyscale images. In this respect, the at least one write data record can include, in particular, a greyscale image data record. In particular, the laser lithography apparatus is controlled according to the gray scale image data. The write exposure data are preferably provided by reading a greyscale image file into a control device of the laser lithography device and storing it in a memory.

With the type of 3D laser writing used here, it can be particularly advantageous if the exposure dose is introduced by means of multi-photon absorption. For this purpose, the lithographic material is preferably designed in such a way and the writing laser beam is matched to the lithographic material in such a way that a change in the lithographic material (for example local polymerisation) is only possible by means of the absorption of a plurality of photons. For this purpose, for example, the wavelength of the writing laser beam can be selected (and thus the associated quantum energy can be dimensioned such) that the energy input required for changing the lithographic material is only achieved by simultaneous absorption of two or more quanta. The probability of such a process is non-linearly dependent on the intensity and is significantly increased in the focus area compared to the rest of the writing laser beam. From fundamental considerations it follows that the probability of absorption of two or more quanta can depend on the square or a higher power of the radiation intensity. In contrast to this, the probability for linear absorption processes shows a different intensity dependence, in particular with a lower power of the radiation intensity. Since the penetration of the write laser beam into the lithographic material is attenuated (e.g. according to Beer's law), writing in the focus area using linear absorption processes deep below the liquid surface of the lithographic material would be problematic, since due to the attenuation even when focusing below the surface in the focus area does not necessarily have the highest absorption probability. The mechanism of multi-photon absorption, on the other hand, makes it possible to introduce the desired exposure dose and to change the lithographic material locally even inside a volume of lithographic material, i.e. also comparatively deep below the liquid surface. Devices for gradually lowering a support structure in a bath of lithographic material, as is known in the prior art, are therefore not required.

In the present context, lithographic material is basically defined as substances whose chemical and/or physical material properties can be changed by irradiation with a write laser beam, for example so-called lithographic lacquers. Depending on the type of changes induced by the writing beam, lithography materials can be divided into so-called negative resists (in which irradiation causes local curing or solubility in a developer medium is reduced) and so-called positive resists (in which irradiation locally increases solubility in a developer medium ) can be distinguished.

The object set at the outset is also achieved by a laser lithography device according to claim 13 . The laser lithography device is designed to produce a three-dimensional target structure in a lithography material. The laser lithography apparatus includes a positioning device for displacing and positioning a substrate. In particular, the positioning device is designed to displace the substrate in all three spatial directions (X, Y, Z), preferably also to tilt it about at least one axis of inclination parallel to the X-Y plane.

The laser lithography device also includes a laser source for emitting a writing laser beam and an optics device. The optics device comprises a beam guiding device, in particular comprising optics means such as lenses, mirrors, etc., for defining a beam path for the writing laser beam from the laser source to the lithographic material. In addition, the optics device includes focusing optics, which are designed to focus the writing laser beam in a focus area. In order to shift the focus area of the writing laser beam relative to the lithographic material, the optics device also includes a scanning device. The scanning device can be a deflection device (eg comprising deflection mirrors) for changing a position of the focus area of the writing laser beam in the lithographic material. The optics device can also include a beam shaping device and/or a modulation device for shaping suitable beam pulses.

The laser lithography device also includes a measuring device for detecting radiation emitted by the lithography material and/or the substrate, in particular reflected radiation or radiation generated by fluorescence. The measuring device can in particular comprise measuring optics, which are preferably designed to be confocal to the device (e.g. beam guiding device) that generates the writing laser beam. In particular, the measuring device comprises a detection device for detecting radiation which is backscattered by the substrate and/or the lithographic material, reflected or generated by fluorescence.

The laser lithography device also includes a control device which is set up to carry out the methods explained above. The control device includes, in particular, a computing unit and a non-volatile memory in which the data sets explained above are or can be stored.

The invention is explained in more detail below with reference to the figures.

• 1 vereinfachte schematische Darstellung einer Laserlithographie-Vorrichtung;
• 2 skizzierte Darstellung zur Erläuterung eines Schreibvorgangs mittels der Laserlithographie-Vorrichtung;
• 3 skizzierte Darstellung zur Erläuterung des Verfahrens zur Lokalisierung einer Grenzfläche zwischen Substrat und Lithographiematerial; und
• 4-7 skizzierte Darstellungen zur Erläuterung verschiedener Vorgehensweisen zur Anpassung des Schreibvorgangs in Abhängigkeit einer ermittelten Position der Grenzfläche.

Show it:

• 1 simplified schematic representation of a laser lithography device;
• 2 Sketched representation to explain a writing process using the laser lithography device;
• 3 Sketched representation to explain the method for localizing an interface between substrate and lithographic material; and
• 4-7 Sketched representations to explain different procedures for adapting the writing process depending on a determined position of the interface.

In the following description and in the figures, the same reference symbols are used for identical or corresponding features.

the 1 FIG. 12 shows a schematic representation of a laser lithography device, which is denoted overall by the reference numeral 10. FIG. The laser lithography device 10 includes a laser source 12 for emitting a writing laser beam 14. The laser lithography device 10 also includes an optics device denoted overall by the reference numeral 16.

The optics device 16 includes a beam guiding device 18 for defining a beam path 20 for the writing laser beam 14 from the laser source 12 to a lithographic material 22 to be structured. In the example shown, the beam guiding device 18 has a plurality of modules which fulfill optical and/or mechanical functions. For example, the beam path 20 can first run through a beam shaping device 24 for shaping suitable beam pulses.

The optics device 16 also includes focusing optics 26 for focusing the writing laser beam 14 in a focus area 28 (cf. also 2 ). The focusing optics 26 include, for example, a lens module 30 through which the writing laser beam 14 is radiated into the lithography material 22 .

The optics device 16 also includes a scanning device 32, by means of which the focal area 28 of the writing laser beam 14 is scanned within a writing area 34 of a scanning surface 36 (cf. 2 ) can be displaced relative to the lithographic material 22 with a precision required for structuring. In the example shown, the scanning device 32 includes a beam steering module 36 which can include, for example, a galvanometer scanner unit for the controlled deflection of the laser beam 14 .

As in 1 shown in outline, the lithographic material 22 is provided on a substrate surface 38 of a substrate 40 . By way of example and preferably by means of a positioning device 42 , the substrate 40 can be displaced in a precise position relative to the focus area 28 of the writing laser beam 14 . The figures also show a coordinate system with mutually orthogonal axes x, y, z. The positioning device 42 is preferably for this purpose designed to displace the substrate 40 in all three spatial directions x, y, z, in particular also to tilt it about a first axis of inclination parallel to the x-axis and/or about a second axis of inclination parallel to the y-axis.

The laser lithography device 10 also includes a control device (not shown), which includes a computing unit and a non-volatile memory.

To generate a three-dimensional target structure 44 in the lithographic material 22, the focus area 28 of the laser writing beam 14 is displaced by the optics device 16, in particular by the scanning device 32, through the volume of lithographic material 22 (surrounding the entire structure). In the focus area 28 of the laser writing beam 14, a write exposure dose is radiated locally into the lithographic material 22, so that structural areas 46 are defined locally, in particular using multi-photon absorption (cf. 2 ). For example, the lithographic material 22 is locally polymerized and thus structured.

As in 2 outlined, the structure 44 can be defined in particular in that the focal area 28 runs through a scan manifold 48 along the scan surface 36 through the lithographic material 22 and in the process emits a series of laser pulses with a defined pulse rate and pulse length (in the 2 the scanning surface 36 is sketched in sections). This defines a series of structure regions 46 (voxels) along the scan manifold 48, which define the target structure 44 (in 2 shown in dashed lines) approximate. The structural areas 46 are similar in shape or identical in shape to one another. The size of a written structure area 46 and thus a structure height is related to the introduced exposure dose.

If the desired target structure 44 is larger than the maximum writing area 34 of the laser lithography apparatus 10, the target structure 44 can be computationally broken down into substructures which together approximate the target structure 44. The substructures can then be written sequentially. the 2 FIG. 1 shows an example in which the target structure 44 is broken down into two partial structures 50-1, 50-2 lying laterally next to one another, which in turn are made up of two write layers 52-1, 52-2 lying one above the other. To write the target structure 44, for example, the in 2 substructure 50-1 shown on the left are written, in which the writing positions 52-1, 52-2 are defined one after the other. For this purpose, the substrate 40 is moved downwards (in the negative z-direction) by a corresponding amount, for example after the writing of the first layer 52-1, in order to write the second layer 52-2. After the first partial structure 50-1 has been defined, the writing area 34 is then lateral to the optical axis (in which in 2 example shown in the x-direction) in order to write the second partial structure 50-2. The writing area 34 can be relocated, for example, by relocating the substrate 40 and/or the lens module 30 . The second partial structure 50-2 is then written in an analogous manner.

The displacement of the writing laser beam 14 and the location-dependent irradiation of the writing exposure dose within the scanning area 36 takes place according to predetermined writing instructions, which are preferably stored as a writing data record in the control device of the laser lithography device 10 . The write data record includes, by way of example and preferably, write exposure data which represent a location-dependent local write exposure dose for the scan manifold 48 . In particular, the writing exposure data can be greyscale image data representing the target structure 44, with different greyscales representing different exposure doses. For example, it is possible for a greyscale image file to be read into the control device of the laser lithography device 10 . The write data record preferably also includes control data for controlling the optics device 16. In particular, the write data record includes control data for controlling the scanning device 32 and/or the beam shaping device 24.

Before the structure is actually defined, an interface 54 between substrate 40 and lithographic material 22 is localized according to the method (cf. 1 ). Specifically, by way of example and preferably, a position of the substrate 40 along the z-axis is determined, in which the focus region 28 lies within the boundary surface 54 (hereinafter referred to as “focus position”).

In an ideal system, in which the substrate surface 38 and the scan area 36 run plane-parallel, this focus position is identical for all scan points within the scan area 36 . However, in a real system, a focus position regularly deviates from each other due to various effects within the scanning area 36 . For example, it can happen that the substrate 40 is tilted relative to the optical axis. In addition or as an alternative, it can also happen that the substrate surface 38 is curved or arched or has local unevenness. In addition, it was recognized that the scanning surface 36 can also deviate from the ideal shape of a plane, for example due to optical errors in the optical device 16.

2 visualizes the exemplary case that the substrate 40 is tilted about the y-axis and, in addition, the scanning surface 36 has both a curvature and a tilting about the y-axis. Such deviations from the ideal configuration can result in an actually written structure 46 not exactly corresponding to the desired target structure 44, e.g. being distorted or incompletely manufactured (in which case in 2 In the example shown, for example, the respective upper right corner of the partial structures 50-1, 50-2 is not completely filled by a structure area 46).

In order to be able to detect and compensate for such deviations of the substrate 40 and/or the scanning surface 36 from the ideal configuration, the focus position of the substrate 40 is determined according to the method at a plurality of test positions 56-1 to 56-6 within the writing area 34 of the scanning surface 36 . If the target structure 44 is as above with respect to FIG 2 explained, made up of a plurality of substructures 50-1, 50-2, the determination of the focus positions is preferably carried out separately for each substructure 50-1, 50-2. In this respect, the focus position is determined again at a plurality of positions within the writing area 34, in particular after the writing area 34 has been shifted to write a further partial structure.

According to the method, the focal area 28 of the writing laser beam 14 is shifted sequentially to different test positions 56 - 1 to 56 - 6 within the scanning area 36 by means of the optics device 16 . A test exposure dose is then radiated locally into the lithographic material 22 at each test position 56-1 to 56-6 (in 5 visualized by the oval structures) and detects a detection radiation emitted by the lithographic material 22 and/or the substrate 40 in response to the test exposure dose. For this purpose, the laser lithography device 10 can then have a corresponding measuring device 58 (cf. 1 ) exhibit.

According to an advantageous embodiment, a plurality of laser pulses are irradiated at each test position 56 - 1 to 56 - 6 and meanwhile the substrate 40 is displaced along the z-axis by means of the positioning device 42 . In this way, a measurement curve can be obtained which represents a response of the substrate 40 or of the lithographic material 22 as a function of a z-position of the substrate 40 .

The detection radiation can in particular be radiation backscattered by the lithographic material 22 and/or the substrate 40 . A focus position of the substrate 40 can then be determined, for example, by detecting a reflection signal of the laser beam 14 at the interface 54, for example as a local intensity maximum. It is also possible for the detection radiation to be radiation generated by fluorescence. A focus position can then be determined, for example, by detecting a difference in the fluorescence signal at the transition from the, in particular, fluorescent, lithography material 22 and the, in particular, non-fluorescent, substrate 40 . For this purpose, the measuring device 58 can in particular have a fluorescence detector.

On the basis of the focus positions determined at the respective test positions 56-1 to 56-6, the at least one write data record can then be adjusted accordingly in order to compensate for the deviations from an ideal system. In particular, at least one corrected write data record can be determined with the aid of a computer, for example by means of the control device, on the basis of which the laser lithography device 10 is then controlled in order to produce the target structure 44 .

For example, it is conceivable that a local writing exposure dose is adjusted as a function of the determined position data. the 4 shows a corresponding example, in which, compared to that in 2 illustrated example, an exposure dose along the scan manifold 48 was adjusted in a location-dependent manner in order to achieve a better approximation of the actually generated structure 46 to the desired target structure 44 (the respective upper right corner of the partial structures 50-1, 50-2 is now surrounded by structure regions 46 better filled in). In such a case, the corrected write data set can then include corrected write exposure data. In the case of configurations that are not shown, it is also possible for a curvature of the substrate surface 38 and/or local unevenness in the substrate surface 38 to be additionally or alternatively compensated for by the corrected writing exposure data.

It is also conceivable for the target structure 44 to be broken down into newly defined structure areas 46 by means of computation as a function of the determined position data. An example of this is in 5 outlined, in which the partial structures 50-1, 50-2 are now built up by four writing layers 52-1 to 52-4 instead of two.

Alternatively or additionally, it is also possible for the substrate 40 to be repositioned as a function of the determined position data. The corrected write data record can then also include corrected control instructions for the positioning device 42 . 6 visualizes the exemplary case that the substrate 40, starting from the in 2 configuration shown is horizontal.

Alternatively or in addition, it is also possible for the lens module 30, or a lens of the lens module 30, to be repositioned, for example tilted, relative to the substrate 40 as a function of the determined position data. The corrected write data set can then also include corrected control instructions for a positioning device (not shown) of the objective module 30 .

Alternatively or additionally, it is also possible for a shape of the scanning surface 36 to be adapted by beam shaping or by the scanning device 32 . 7 FIG. 12 outlines the exemplary case in which the scanning surface 36 was straightened and aligned parallel to the substrate surface 38. In this case, the corrected write data record can include corrected control data for the optics device 16, in particular for the beam shaping device 24 and/or the scanning device 32. For example, it is conceivable that a scanning device 32 is provided, which is designed to quickly change a Z position of the focus area during scanning and thus adapt a shape of the scanning surface 36 . For this purpose, the scanning device 32 can comprise, for example, adaptive lenses which are designed to quickly shift the focus area along the z-axis.

As part of an alternative embodiment of the method, a calibration laser beam that is separate from the write laser beam 14 can also be used to radiate the test exposure dose. The calibration measurements for determining a focus position are then not carried out with the writing laser beam 14 itself. In such a configuration, the laser lithography device can include, in particular, a second laser source (not shown) for emitting the calibration laser beam. The second laser source is designed and arranged in particular in such a way that the calibration laser beam has the same beam path 20 through the optics device 16 as the writing laser beam 14, in particular at least through the beam shaping device 24 and/or the scanning device 32. In such an embodiment of the method, the focus position can also be determined by the writing laser beam 14 during the actual writing process. The laser writing beam 14 and the calibration laser beam can therefore be used in parallel.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102017110241 A1 [0002]
• US7893410B2 [0004]

Claims (15)

Method for producing a three-dimensional target structure (44) in a lithographic material (22) by means of a laser lithography device (10), wherein a substrate (40) with lithographic material (22) arranged thereon is provided, wherein an interface (54) between lithographic material (22 ) and substrate (40) is localized, wherein the target structure (44) is defined in that a focus area (28) of a writing laser beam (14) by means of an optical device (16) within a writing area (34) of a scanning area ( 36) is shifted, with a write exposure dose being radiated into the lithography material (22) in the focus area (28) of the writing laser beam (14) and a structural area (46) being defined locally, characterized in that for locating the interface ( 54) between substrate (40) and lithography material (22) a focus area (28) of a calibration laser beam (14) by means of the optics device ution (16) is sequentially shifted to a plurality of test positions (56-1 to 56-6) within the writing area (34) of the scanning surface (36), wherein at each test position (56-1 to 56-6) a test exposure dose is radiated into the lithographic material (22) and position data of the interface (54) are determined from a response of the lithographic material (22) and/or the substrate (40) to the test exposure dose. procedure after claim 1 , wherein the writing area (34) is sequentially displaced and positioned laterally to the optical axis (z) relative to the substrate (40), and wherein the boundary surface (54) between the substrate (40) and the lithographic material (22 ) is localized. Procedure according to one of Claims 1 or 2 , wherein a radiation backscattered by the lithography material (22) and/or the substrate (40) or generated by fluorescence is detected by means of an optical measuring device (58) in order to determine the position data. Method according to one of the preceding claims, wherein the position data represent a focus position of the substrate (40) along the optical axis (z), in which the focus area (28) of the calibration laser beam (14) is in the interface (54) between the lithographic material (22 ) and substrate (40). Method according to one of the preceding claims, wherein a plurality of laser pulses are irradiated at each test position (56-1 to 56-6) and the substrate (40) is moved along the optical axis (z) of the calibration laser beam (14) during this time . Method according to one of the preceding claims, wherein the test exposure dose is selected so low that no structuring occurs in the lithographic material (22). Method according to one of the preceding claims, in which the focus area (28) of the calibration laser beam (14) is wobbled laterally when the test exposure dose is radiated in. Method according to one of the preceding claims, in which the writing laser beam (14) is used as a calibration laser beam. Method according to one of the preceding claims, the optics device (16) and/or at least one writing instruction being changed as a function of the determined position data. Method according to one of the preceding claims, wherein the writing laser beam (14) for defining the target structure (44) passes through a scanning manifold (48) within the writing region (34), wherein, depending on the determined position data, at least for a subset of the scanning points of the Scan manifold (48) a local writing exposure dose is changed. Method according to one of the preceding claims, wherein a configuration of the scanning surface (36) is changed as a function of the determined position data, in particular the scanning surface (36) is aligned by changing the optical device (16) relative to the substrate (40), further in particular straightened and / or is tilted relative to the substrate (40). Method according to one of the preceding claims, in which a position and/or location of the substrate (40) is changed as a function of the position data. Method according to one of the preceding claims, wherein the write instructions are stored in at least one write data record, at least one corrected write data record being determined on the basis of the determined position data of the interface (54), the laser lithography device (10) being controlled in accordance with the at least one corrected write data record is, in particular wherein the write data record comprises control data for controlling the optical device (16) and/or write exposure data which represent a location-dependent local exposure dose for each scan point. Laser lithography device (10) for producing a three-dimensional target structure (44) in a lithographic material (22), comprising - a positioning device (42) for displacing and positioning a substrate (40); - A laser source (12) for emitting a writing laser beam (14); - an optical device (16) comprising o a beam guiding device (18) for defining a beam path (20) for the writing laser beam (14) from the laser source (12) to the lithographic material (22), o focusing optics (26) for focusing the Writing laser beam (14) in a focal area (28), o a scanning device (32) for shifting the focal area (28) of the writing laser beam (14) within a scanning area (36) relative to the lithographic material (22) . by a measuring device (58) for detecting radiation emitted by the lithography material (22) and/or the substrate (40), esp. reflected or generated by fluorescence, and by a control device which is set up to carry out the method according to one of Claims 1 until 13 to execute. Laser lithography device Claim 14 , further comprising a second laser source for emitting a calibration laser beam.

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