US-12625426-B2 - Process for creating a three-dimensional structure in a lithography material via a laser lithography device

US12625426B2US 12625426 B2US12625426 B2US 12625426B2US-12625426-B2

Abstract

Method (and apparatus) for producing a 3D target structure in lithographic material. Focus region of a laser writing beam travels through a scanning manifold through the lithographic material. In the focus region of the laser writing beam, an exposure dose is irradiated into the lithographic material, and a structure region is locally defined. At least one exposure data set which represents a local exposure dose for the scan manifold as a function of location is determined. A structure which approximates the target structure is defined based on at least one exposure data set. This structure is analyzed and at least one analysis data set which represents the analyzed structure is determined. Deviation data set which represents deviations of the already defined structure from the target structure is determined. At least one correction exposure data set is determined. Correction structure based on the at least one correction exposure data set is defined.

Inventors

Nicole Lindenmann
Matthias BLAICHER
Jörg Hoffmann

Assignees

NANOSCRIBE HOLDING GMBH

Dates

Publication Date: 20260512
Application Date: 20220404
Priority Date: 20210428

Claims (16)

1 . A method for producing a three-dimensional target structure in a lithographic material by means of a laser lithography apparatus, wherein the target structure is defined in that, within a writing region of the laser lithography apparatus, a focus region of a laser writing beam travels through a scanning manifold through the lithographic material, wherein, in the focus region of the laser writing beam, an exposure dose is irradiated into the lithographic material and a structure region is locally defined, the method comprising: a) providing at least one exposure data set which represents a local exposure dose for the scan manifold as a function of location; b) defining a structure which approximates the target structure on the basis of the at least one exposure data set, wherein the structure is defined utilizing multi-photon absorption, wherein the lithographic material is designed in such a way and the laser writing beam is tuned to the lithographic material in such a way that a change in the lithographic material is only possible by means of the absorption of multiple photons; c) analyzing an already defined structure, said already defined structure being defined according to b), by means of a spatially resolving imaging measurement method and determining at least one analysis data set which represents the analyzed structure; d) determining a deviation data set, which represents deviations of the already defined structure from the target structure; e) determining at least one correction exposure data set which represents a correction exposure dose required for compensating for the deviations for the scan manifold as a function of location; and f) defining a correction structure based on the at least one correction exposure data set.
2 . The method according to claim 1 , wherein no development of the lithographic material occurs between defining the structure and analyzing the structure.
3 . The method according to claim 1 , wherein steps c) to f) are repeated iteratively in such a way that the deviation of the already defined structure from the target structure is increasingly reduced, until the determined deviation falls below a prespecified or prespecifiable threshold value.
4 . The method according to claim 1 , wherein the defined structure is analyzed by means of optical microscopy.
5 . The method according to claim 4 , in which, in order to analyze the already defined structure, the same is scanned with the laser writing beam and, for imaging, the backscattered, reflected, transmitted or fluorescence-generated radiation is detected by means of a measuring device, wherein an exposure dose for scanning is selected to be low enough that no structure is defined in the lithographic material.
6 . The method according to claim 4 , in which, in order to analyze the already defined structure, the same is scanned with the laser writing beam and, for imaging, the backscattered, reflected, transmitted or fluorescence-generated radiation is detected by means of a measuring device.
7 . The method according to claim 1 , in which, in order to analyze the already defined structure, the same is mechanically scanned with a scanning tip.
8 . The method according to claim 1 , wherein the target structure is defined by a plurality of partial structures being defined sequentially, which together approximate the target structure, wherein further partial exposure data sets are determined by computer for defining the partial structures from the at least one exposure data set and/or the at least one correction exposure data set, which represent a local exposure dose along a scan manifold for each partial structure.
9 . The method according to claim 8 , in which the partial structures are stacked on top of one another in layers.
10 . The method according to claim 8 , wherein the at least one exposure data set and the at least one correction exposure data set each comprise at least one grayscale image data set, wherein different gray values represent different exposure doses, and wherein, in order to determine the partial exposure data sets, the at least one grayscale image data set of the at least one exposure data set and/or the at least one correction exposure data set is divided into a plurality of partial grayscale image data sets which together form an image stack along the stacking direction of the partial structures.
11 . The method according to claim 1 , wherein the at least one exposure data set and the at least one correction exposure data set each comprise at least one grayscale image data set, wherein different gray values represent different exposure doses.
12 . The method according to claim 11 , wherein the at least one analysis data set also comprises at least one grayscale image data set, wherein different gray values represent different structure heights, and wherein the deviation data set is determined by comparing the at least one analysis data set to the at least one exposure data set.
13 . A laser lithography device for producing a three-dimensional target structure in a lithographic material, the laser lithography device comprising: a laser source configured and/or programmed to emit a laser writing beam, a beam guide device configured and/or programmed to define a beam path for the laser writing beam from the laser source to the lithographic material, focusing optics configured and/or programmed to focus the laser writing beam in a focus region, a scanning device configured and/or programmed to displace the focus region of the laser writing beam relative to the lithographic material, an imaging measuring device configured and/or programmed to analyze an already defined structure, and a control device which is configured and/or programmed to carry out the method according to claim 1 .
14 . The method according to claim 1 , wherein steps c) to f) are repeated iteratively in such a way that the deviation of the already defined structure from the target structure is increasingly reduced.
15 . The method according to claim 1 , wherein the defined structure is analyzed by means of confocal fluorescence microscopy.
16 . A method for producing a three-dimensional target structure in a lithographic material, the method comprising: providing at least one exposure data set which represents a local exposure dose for a scan manifold as a function of location; defining a structure which approximates a target structure on a basis of the at least one exposure data set, wherein the structure is defined utilizing multi-photon absorption, wherein the lithographic material is designed in such a way and the laser writing beam is tuned to the lithographic material in such a way that a change in the lithographic material is only possible by means of the absorption of multiple photons; analyzing an already defined structure by a spatially resolving imaging measurement method providing an analyzed structure; determining at least one analysis data set which represents the analyzed structure; determining a deviation data set, which represents deviations of the already defined structure from the target structure; determining at least one correction exposure data set which represents a correction exposure dose required for compensating for the deviations for the scan manifold as the function of location; and defining a correction structure based on the at least one correction exposure data set.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to DE Patent Application No. 10 2021 110 860.8 filed on Apr. 28, 2021, the entire contents of which are hereby incorporated by reference. The invention relates to a method for producing a three-dimensional target structure in a lithographic material by means of a laser lithography apparatus. The invention also relates to a laser lithography apparatus adapted for the method. Techniques of this type are used in particular in the production of microstructures 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 radiating an exposure dose into a lithographic material in a focus region of a laser writing beam, and thus locally defining a structure region, for example by locally hardening or polymerizing the lithographic material. A three-dimensional overall structure can then be produced by displacing the focus region in the lithographic material. A laser lithography method is known from DE 10 2017 110 241 A1, in which a surface of a desired structure is produced by locally varying the radiated exposure dose (exposure variation). In order to be able to produce structures with high precision using such an exposure variation, a connection must be established between the exposure dose and the exposure result. A corresponding calibration process is typically required for this purpose. For this purpose, it is known to produce reference structures with prespecified exposure doses before actually writing a desired structure, then to develop them and subsequently to measure their surface optically or mechanically. Depending on the measurement results, the exposure dose is then usually adjusted accordingly, and the process is repeated iteratively until the result achieved meets the specified requirements. However, such an optimization process is usually time-consuming and difficult to automate. In addition, such a calibration process usually has to be carried out again at certain time intervals. The object of the invention is to produce a three-dimensional structure with high precision in a lithographic material in a simple and rapid manner. This object is achieved by a method according to claim 1. The method is a laser lithography method, in particular so-called direct laser writing, by means of a laser lithography apparatus, in a volume of lithographic material and/or in a volume filled with lithographic material. According to the method, a target structure is written and/or defined in the lithographic material by sequentially defining a plurality of structure regions (hereinafter also referred to as “voxels”) that add up to form the target structure (that is, by “writing” in the lithographic material with the laser lithography apparatus). To write the structure regions and thus the target structure, a focus region of a laser writing beam runs through a scan manifold through the lithographic material. In a simple case, the scan manifold can be a scan curve, but it can also be made more complex. In other words, the focus region of the laser writing beam is displaced through the lithographic material. For this purpose, the laser writing beam is controllable within a writing region of the laser lithography apparatus with the precision required for structuring purposes. By way of example, the laser writing beam can be deflected in a controlled manner by means of a beam guide device. However, it is also conceivable for the lithographic material or a substrate having the lithographic material to be displaced in a controlled manner relative to the laser writing beam by means of a positioning device. The two concepts for displacement can also be used together. An exposure dose is irradiated into the lithographic material in the focus region of the laser writing beam, and, in particular utilizing multi-photon absorption, the lithographic material is locally modified, and thus a structure region is produced or written. In this respect, the lithographic material is structured locally, in particular utilizing multi-photon absorption. In particular, the lithographic material is chemically and/or physically modified, for example hardened or polymerized, by the exposure dose of the laser writing beam. The exposure dose is in particular a volume dose of radiant energy. The size of the modified structure region (“voxels”) in the lithographic material depends on the exposure dose. By varying the exposure dose, the spatial expansion of each of the structure regions or voxels, in particular a structure height, can be modified. Applying the exposure dose by means of multi-photon absorption can be particularly advantageous in the type of 3D laser writing used in the present case. For this purpose, the lithographic material is preferably designed in such a way and the laser writing beam is tuned to the lithographic mat