DE102020213420B4 - Method and device for parallel alignment of a first surface of a first substrate with respect to a second surface of a second substrate - Google Patents

Abstract

A method of aligning a first surface (112) of a first substrate (114) in parallel with a second surface (116) of a second substrate (118), comprising the steps of:a) positioning a first substrate (114) having a first periodic structure ( 128), and a second substrate (118), to which a second periodic structure (132) is assigned, spaced within a depth of field of an objective (138) of imaging optics (134), wherein a first surface (112) of the first substrate (114 ) relative to a second surface (116) of the second substrate (118) has a tilt (154);b) observing a Moiré pattern (174, 176, 178) that is formed by superimposing the first periodic structure (128) with the second periodic structure (132) is formed by means of the imaging optics (134); c) successively changing a tilt angle φ between the first surface (112) of the first substrate (114) and the second surface (116) of the second substrate (118) while maintaining an angle of rotation α between the first substrate (114) and the second substrate (118), and determining an extreme value for a detection angle δ dependent on the tilt angle φ from the moiré pattern (174, 176, 178) ; andd) adjusting the tilt angle ϕ between the first surface (112) of the first substrate (114) and the second surface (116) of the second substrate (118) to a value for the tilt angle ϕ associated with the extreme value for the detection angle δ, whereby the tilting (154) of the first surface (112) of the first substrate (114) versus the second surface (116) of the second substrate (118) is compensated.

Description

field of invention

The present invention relates to a method and a device for parallel alignment of a first surface of a first substrate with respect to a second surface of a second substrate. The method and the device are particularly suitable for use in a transfer, referred to as “printing”, of a substance from the first surface of the first substrate to the second surface of the second substrate, on which they form or modify a surface structure. Further applications are conceivable.

State of the art

The present invention is located in particular in the field of scanning probe lithography, preferably stamp-based contact printing methods, specifically “microcontact printing”. A structure-generating first substrate, also known as a “stamp”, which is wetted with a substance that is often referred to as “ink”, is applied to a second substrate using a scanning probe microscopic arrangement, in particular pressed, in order to at least partially deposit the substance there. So that the first substrate can be used in particular to generate any pattern on the second surface of the second substrate, the first surface of the first substrate can have arrays of dot-generating structures that make it possible to print the desired pattern several times while shifting the first To rasterize the substrate between successive printing steps. Alternatively, the structures can already be present on the first substrate, in particular by producing the first substrate by means of photolithography. In this embodiment, multiple printing can be omitted since the desired structure could be produced directly on the second surface of the second substrate.

Since the first substrates used as stamps usually represent consumables that are regularly exchanged, the problem can arise in particular that the respective first surfaces of the first substrates are not used completely parallel to the second surface of the second substrate. Furthermore, in the event that the second substrate has a structure that is already present, the problem can arise that the first substrate should be aligned as precisely as possible with the structure that is already present on the second substrate. Rather, a random tilting and twisting of the first surface of the first substrate relative to the second surface of the second substrate can result. As a result of the tilting relative to the second surface of the second substrate, different points on the first surface of the first substrate can come into different degrees or under certain circumstances not at all in contact with the second surface of the second substrate, as a result of which an uneven lithography result is obtained. As a result of the twisting of the first surface of the first substrate relative to the second surface of the second substrate, the problem of an offset between patterns formed by different segments of the first substrate on the second surface of the second substrate can occur, especially with long traverse paths in multi-color printing , appear.

Both types of deviations in the form of tilting and/or twisting of the first surface of the first substrate used as a stamp facing the second surface of the second substrate compared to the second surface of the second substrate are usually compensated in the prior art by manual corrections and test prints for offset correction . Specifically, the user can bring the stamper into contact with the second surface of the second substrate, judge by eye the deformation of peaks in the various portions of the stamper, and then correct the position of the stamper. After the alignment has been corrected by tilting the first and/or the second substrate, it can be advantageous to repeat the assessment several times until the user is satisfied with the result. Overall, however, the result is heavily dependent on the personal experience of the user, and the time required can vary considerably. In addition, mixing of different inks can occur during the test print and possibly lead to cross-contamination. It is also necessary to add a fluorescent component to each ink to enable microscopic evaluation of the test print. In addition, the test prints require an increased expenditure of time.

X. Liao, AB Braunschweig, CA Mirkin, Nano Lett. 2010, 10, 1335; H. Noh, G.-E. Jung, S. Kim S.-H. Yun, A.Jo, S.J. Kahng, N.-J. Cbo, S.-J. Cho, Small 2015, J 1, 4526; S Wang, J Hosford, WP Heath, LS Wong, RSC Adv 2015, 5, 61402; IN. Lee, J Hosford, S

Wang, JA Hunt, JM Curran, WP Heath, LS Wong, J. Vis. Exp. 2018, e56967, therefore propose determining and then compensating for the tilting of the first substrate in relation to the second substrate using a contact force which is measured by means of force sensors, in particular by means of a scale, in a substrate holder. In this way, although a Kor achieve correction of the tilting, but this requires a lot of time and equipment, and integration into a printer environment is practically impossible.

WO 2006/087 138 A1 discloses a security element for protecting valuables with a first and a second authenticity feature. The first authenticity feature comprises a first arrangement with a multiplicity of focusing elements, which are present in a first raster, and a second arrangement with a multiplicity of microscopic structures, which are present in a second raster. The first and second arrays are arranged in such a way that the microscopic structures of the second array can be seen in magnification when viewed through the focusing elements of the first array. The second authenticity feature can be checked mechanically and/or visually and is not influenced by the first arrangement of the first authenticity feature. In particular, the microscopic structures can include embossed microstructures, which can serve as alignment structures.

DE 693 25 678 T2 discloses a method and apparatus for aligning a lenticular apparatus having a recording medium having an alignment guideline recorded thereon and a lenticular overlay slidably mounted on the recording medium to project the alignment guideline as a projected image, comprising a light sensor for sensing the image on the lenticular overlay projected alignment guide and positioning means for positioning the lenticular overlay, arranged to rotate and align the lenticular array in response to at least one brightness peak in a moiré pattern projected by the lenticular array and sensed by the light sensor.

US 5,991,004A discloses a focus shift sensor comprising a light source that directs light through a first grating to form a light pattern. The pattern is passed through a lens that images the pattern onto a second grid. The two gratings have different periods, so the second grating produces moiré fringes that are projected onto a CCD array. The second grating is preferably tilted with respect to the image plane of the pattern of the first grating, so that only part of the second grating is in the focal range of the lens. This creates a pattern of truncated moiré fringes. If the focus area shifts along the second grid, the moiré fringes move along the CCD line. The movement of the moiré fringes is tracked and a system is adjusted to keep the focal plane of the lens at the desired location.

object of the invention

Based on this, the object of the present invention is to provide a method and a device for the parallel alignment of a first surface of a first substrate with respect to a second surface of a second substrate, which at least partially overcomes the known disadvantages and limitations of the prior art.

The method and the device are intended in particular to enable a fully automatic alignment of a surface of the first substrate, which is often used as a stamp, in which, after the arrangement of the first surface of the first substrate in relation to the second surface of the second substrate, at least one parameter can be determined which is used to compensate for the deviations occurring in the form of tilting and/or twisting of the first surface of the first substrate compared to the second surface of the second substrate and can be easily transferred to a printer's control software, which means that manual intervention by a user in the mutual arrangement of the two substrates can be avoided.

Furthermore, in the event that the second substrate has a structure that is already present, the problem can arise that the first substrate should be aligned as precisely as possible with the structure that is already present on the second substrate.

In addition, test prints should become superfluous, in particular in order to significantly reduce the time and/or material expenditure for an entire printing process and to avoid cross-contamination of substances that are provided on the first surface of the first substrate and at least partially transferred to the second surface of the second substrate, as far as possible largely to be avoided.

Disclosure of Invention

This object is achieved by a method and a device for parallel alignment of a first surface of a first substrate with respect to a second surface of a second substrate according to the features of the independent claims. Advantageous developments, which can be implemented individually or in any combination, are presented in the dependent claims.

In a first aspect, the present invention relates to a method for parallel alignment of a first surface of a first substrate with respect to a second surface of a second substrate. The terms "first" and "second" are to be understood in a descriptive sense as meaning that they are two similar elements that may be identical, have at least one identical geometric feature, or are arranged to perform at least a partially identical function, but are located at different locations in space , distinguishable from each other, without establishing an order in this regard.

The term “substrate” refers to a flat carrier element that is set up to receive and/or release at least one substance, which is often also referred to as “ink” in this context. If the two substrates are used in a printing process, the first substrate, which is designed in particular to receive and release the at least one substance, can also be referred to as a "transfer substrate" or as a "carrier substrate", while the second substrate, which is only used for Recording the at least one substance is set up by the first substrate, can be provided with the designation "substrate to be coated". However, other ways of naming the substrates are conceivable. In particular, in order to have the highest possible surface area available for receiving and releasing the at least one substance while at the same time having the lowest possible weight, the carrier element can preferably be an extended surface in two dimensions, each having an at least partially, preferably completely, flat surface Act body that has a small layer thickness in the third dimension in the perpendicular direction. An expansion of the surface of the carrier element can preferably exceed the layer thickness of the carrier element by a factor of at least 10, preferably at least 50, particularly preferably at least 100.

In a particularly preferred configuration, the substrate can comprise a plane-parallel carrier element. The term "plane-parallel support element" refers to a support element in which the two extended planar surfaces of the support element are arranged parallel to one another. In this configuration, the substrate can thus be assigned a “substrate plane” which is parallel to and equidistant from the two extended planar surfaces of the carrier element.

It is particularly important not only to achieve uniform printing of the second surface of the second substrate with substances released from the first surface of the first substrate, but also to be able to carry out the printing at at least one point provided for this purpose on the second surface of the second substrate advantageous if both a tilting between the two surfaces and a twisting of the two surfaces to each other can be avoided. The term "parallel alignment" therefore means that the first surface of the first substrate, which faces the second surface of the second substrate, is aligned with respect to the second surface of the second substrate in such a way that the two surfaces are arranged parallel to one another, so that no tilting between the two flat surfaces occurs. A plane-parallel alignment of the first surface of the first substrate, which is at least partially, preferably completely, flat, is particularly preferred here, compared to the second surface of the second substrate, which is also at least partially, preferably completely, flat. The term "plane-parallel alignment" therefore means that a surface normal of the first flat surface of the first substrate, which faces the second flat surface of the second substrate, is aligned parallel to a surface normal of the second flat surface of the second substrate. The term "surface normal" of a surface designates a spatial vector which assumes a direction that is perpendicular to the associated surface. The term "tilting" thus designates an angle between the first surface normal and the second surface normal that is different from n · 180°, n = 0, 1, 2, etc.

In addition, however, the term “parallel alignment” can preferably also include that in each case at least one structural feature on each of the two planar surfaces matches in such a way that no twisting occurs between the two surfaces. The structural feature can include, in particular, an alignment of at least one edge of the carrier structure or a structure attached to both surfaces that can define an orientation on the surface of the respective carrier structure, for example lines or linear patterns. Thus, the term "twist" denotes an angle different from n - 180°, n = 0, 1, 2, etc., between a first structural feature on the first surface of the first substrate and a second structural feature on the second surface of the second substrate. In other words, the term "angle of rotation" refers to an orientation between the first substrate and the second substrate in relation to a straight line perpendicular to the first surface and the second surface.

1. a) Positionieren eines ersten Substrats, das eine erste periodische Struktur aufweist, und eines zweiten Substrats, dem eine zweite periodische Struktur zugeordnet ist, beabstandet innerhalb eines Schärfentiefenbereichs eines Objektivs einer Abbildungsoptik;
2. b) Beobachten eines Moire-Musters, das durch eine Überlagerung der ersten periodischen Struktur mit der zweiten periodischen Struktur gebildet wird, mittels der Abbildungsoptik;
3. c) Sukzessives Ändern eines Kippwinkels zwischen der ersten Oberfläche des ersten Substrats und der zweiten Oberfläche des zweiten Substrats unter Beibehaltung eines Drehwinkels zwischen dem ersten Substrat und dem zweiten Substrat, und Bestimmen eines Extremwertes für einen von dem Kippwinkel abhängigen Nachweiswinkel aus dem Moire-Muster; und
4. d) Einstellen des Kippwinkels zwischen der ersten Oberfläche des ersten Substrats und der zweiten Oberfläche des zweiten Substrats auf einen dem Extremwert für den Nachweiswinkel zugeordneten Wert für den Kippwinkel, wodurch eine Verkippung der ersten Oberfläche des ersten Substrats gegenüber der zweiten Oberfläche des zweiten Substrats kompensiert wird.

The present method for parallel alignment of a first surface of a first substrate with respect to a second surface of a second substrate comprises the steps a) to d) described in detail below, it being possible for the steps to be carried out one after the other or at least partially overlapping. In addition, further steps, in particular step e) mentioned below, can be carried out as part of this method. The individual steps of the present procedure are:

1. a) Positioning a first substrate, which has a first periodic structure, and a second substrate, which is associated with a second periodic structure, spaced apart within a depth of field of an objective lens of imaging optics;
2. b) observing a moiré pattern, which is formed by superimposing the first periodic structure with the second periodic structure, by means of the imaging optics;
3. c) successively changing a tilt angle between the first surface of the first substrate and the second surface of the second substrate while maintaining a rotation angle between the first substrate and the second substrate, and determining an extreme value for a tilt angle-dependent detection angle from the Moire pattern; and
4. d) Adjusting the tilt angle between the first surface of the first substrate and the second surface of the second substrate to a value for the tilt angle associated with the extreme value for the detection angle, whereby tilting of the first surface of the first substrate relative to the second surface of the second substrate is compensated .

According to step a), the first substrate and the second substrate are positioned at a distance within a depth of field of an objective lens of imaging optics. The term “positioning” describes arranging the two substrates in the specified manner. The term "imaging optics" relates to an optical device that is set up to generate at least one image of an object. For this purpose, the imaging optics comprise an objective optics, which in particular comprises at least one objective, which is set up to generate the desired real optical image of the first substrate and the second substrate. The “depth of field” refers to an area that is spatially remote from the lens, within which the first substrate and the second substrate are imaged by means of the lens with a desired sufficient depth of field or depth of field. The lens can have a fixed or adjustable focal length and/or the imaging optics can have a device for setting the depth of field. It can thus be ensured that the observation of a moiré pattern by means of the imaging optics according to step b) actually includes both substrates.

In order to enable the moiré pattern, which is formed by superimposing a first periodic structure with a second periodic structure, to be observed using the imaging optics according to step b), the first substrate also has a first periodic structure, while the second substrate has a second periodic structure is assigned. The term "periodic structure" denotes a multiple repetition of a pattern in at least one direction, in particular a large number of points or lines arranged at the same distance from one another. The term “moire pattern” relates to structures, in particular straight lines referred to as “moire lines”, which are then formed when at least two periodic structures are superimposed and can be observed using the imaging optics according to step b) if the at least two periodic structures have a rotation and / or a tilt to each other. The "moire pattern" can change in particular as a function of the twisting and tilting of the first surface of the first substrate relative to the second surface of the second substrate.

• - Ist das zweite Substrat intransparent, oder ist das zweite Substrat transparent und nicht planparallel, kann die zweite periodische Struktur bevorzugt auf der, der ersten Oberfläche des ersten Substrats und damit dem Objektiv der Abbildungsoptik zugewandten zweiten Oberfläche des zweiten Substrats angeordnet sein, wobei auch hier ein Teilbereich der zweiten Oberfläche des zweiten Substrats, der bevorzugt am Rand der zweiten Oberfläche angeordnet ist, die zweite periodische Struktur aufweisen kann, oder
• - Ist das zweite Substrat transparent und planparallel, kann die zweite periodische Struktur bevorzugt auf einer der ersten Oberfläche des ersten Substrats und damit dem Objektiv der Abbildungsoptik abgewandten weiteren Oberfläche des zweiten Substrats, angeordnet sein, wobei hier die gesamte weitere Oberfläche des zweiten Substrats oder ein Teilbereich davon, der bevorzugt am Rand des zweiten Substrats angeordnet ist, die zweite periodische Struktur aufweisen kann; oder
• - Ist das zweite Substrat transparent und planparallel, kann alternativ eine Unterlage, auf der das zweite Substrat, insbesondere mit der der ersten Oberfläche des ersten Substrats und damit dem Objektiv der Abbildungsoptik abgewandten weiteren Oberfläche, angrenzend aufliegt, die zweite periodische Struktur umfassen, wobei eine von der zweiten periodischen Struktur eingenommene Fläche der gesamten weiteren Oberfläche des zweiten Substrats oder eines Teilbereichs davon, der bevorzugt am Rand des zweiten Substrats angeordnet ist, entsprechen kann oder über die gesamte weitere Oberfläche des zweiten Substrats hinausgehen kann.

In order to enable the moiré pattern to be observed in accordance with step b), a subregion of the first surface of the first substrate, which is preferably arranged at the edge of the first surface, can have the first periodic structure, which in particular has a large number of spaced at the same distance from one another arranged points or lines. With regard to an assignment of the second periodic structure to the second substrate, there are preferably the following configurations, in particular depending on whether the second substrate is opaque or transparent with respect to a wavelength at which the image of the second periodic structure is generated and is plane-parallel or is not designed:

• - If the second substrate is non-transparent, or if the second substrate is transparent and not plane-parallel, the second periodic structure can preferably be arranged on the second surface of the second substrate facing the first surface of the first substrate and thus the lens of the imaging optics, whereby here too a partial area of the second surface of the second substrate, which is preferably arranged at the edge of the second surface, can have the second periodic structure, or
• - If the second substrate is transparent and plane-parallel, the second periodic structure can preferably be arranged on a further surface of the second substrate that faces away from the first surface of the first substrate and thus the lens of the imaging optics, with the entire further surface of the second substrate or a Portion thereof, which is preferably arranged at the edge of the second substrate, can have the second periodic structure; or
• - If the second substrate is transparent and plane-parallel, a base on which the second substrate rests, in particular with the further surface facing away from the first surface of the first substrate and thus the lens of the imaging optics, can alternatively comprise the second periodic structure, wherein a The area occupied by the second periodic structure can correspond to the entire further surface of the second substrate or a part thereof, which is preferably arranged at the edge of the second substrate, or can go beyond the entire further surface of the second substrate.

Irrespective of the configuration chosen for the second periodic structure, according to step b) the moiré pattern formed by the superimposition of the first periodic structure with the second periodic structure can be observed by means of the imaging optics. As can be seen in more detail from the exemplary embodiments presented below, the moiré pattern produced in this way shows a sequential arrangement of regions parallel to one another if, in addition to the tilting between the surfaces of the two substrates, there is also a twisting between the surfaces of the two substrates, one respective orientation of the areas can be assigned an angle referred to here as a “detection angle” in relation to an orientation of at least one of the two substrates, preferably an orientation of an edge of the at least one substrate. While maintaining the rotation of the surfaces of the two substrates having the respective periodic structure, the detection angle in particular can change when the tilt angle of the two substrates relative to one another changes.

As explained in more detail below, a course of the change in the detection angle, which occurs with a successive change in the tilt angle between the first surface of the first substrate and the second surface of the second substrate while maintaining the angle of rotation between the first substrate and the second substrate according to step c ) adjusts, in particular represent a 2nd order function in relation to the tilt angle. The term "successive" denotes a change that takes place in successive steps, e.g. in steps of 0.5°, 1° or 2°, whereby after each step a further observation of the moiré pattern generated in each case according to step b) can be carried out. In particular, the gradual change in the tilt angle can take place in the form of a sweep, preferably over a specified interval, e.g. from -5° to +5° degrees in 1° steps, at specified times, preferably before and after each approach of the first substrate to the second substrate. In a particularly preferred embodiment of the present invention, it may be sufficient if the gradual change in the tilt angle comprises a setting of only three different tilt angles, in particular since three different tilt angle values are sufficient to perform a curve fit of a second-order function.

Irrespective of the exact course of the change in the detection angle in relation to the tilt angle, an extreme value, i.e. a maximum or a minimum, can be determined for the detection angle from the Moiré pattern according to step c). As can be seen from the exemplary embodiments below, a maximum for the detection angle can result from the Moiré pattern in the case of rotations in one direction or a minimum in the case of rotations in the opposite direction.

According to step d), the tilt angle between the first surface of the first substrate and the second surface of the second substrate can then be set to a value for which the extreme value of the detection angle was determined according to step c). In this way, the tilting of the first surface of the first substrate relative to the second surface of the second substrate is compensated for, thereby achieving the inventively desired parallel alignment of the first surface of the first substrate relative to the second surface of the second substrate without tilting.

• e) Sukzessives Drehen des ersten Substrats senkrecht zu der ersten Oberfläche des ersten Substrats und/oder des zweiten Substrats senkrecht zu der zweiten Oberfläche des zweiten Substrats, bis auf der Abbildungsoptik kein Moire-Muster mehr abgebildet wird, wodurch eine Verdrehung der ersten Oberfläche des ersten Substrats gegenüber der zweiten Oberfläche des zweiten Substrats kompensiert wird.

In a particular embodiment of the present invention, the desired parallel alignment of the first surface of the first substrate with respect to the second surface of the second substrate can also be achieved without twisting. For this purpose, the following step e) can preferably be carried out:

• e) Successive rotation of the first substrate perpendicular to the first surface of the first substrate and/or the second substrate perpendicular to the second surface of the second substrate until no moiré pattern is imaged on the imaging optics, causing a twisting of the first surface of the ers th substrate is compensated against the second surface of the second substrate.

According to the optional step e), a successive turning of the first substrate perpendicular to the first surface and/or the second substrate perpendicular to the second surface, in particular in the form of a sweep, can take place, during which the moiré pattern, which is caused by the superimposition of the first periodic structure comprised by the first substrate is formed with the second periodic structure associated with the second substrate, is observed by means of the imaging optics according to step b). With regard to the term “successively”, reference is made to the above definition, which can be used analogously here. If no Moiré pattern can be seen on the imaging optics described in more detail below, it can be assumed that there is no longer any twisting between the two substrates. However, even if the periodic structures on the two surfaces have exactly the same periodicity, no moiré pattern can occur. However, in this special case, which occurs very rarely in practice, a sweep over the two surfaces can be used.

Step e) can be carried out before changing the tilt angle between the two substrates according to step c). In this embodiment, it is therefore advantageous that, during step c), in addition to the tilting between the surfaces of the two substrates, there is also a twisting between the surfaces of the two substrates in order to produce the desired Moiré pattern described above, which is a sequential arrangement of mutually parallel Areas that take a detection angle to each other, shows to generate when, after determination and compensation of the rotation of the two substrates to each other according to step e), a renewed intentional rotation of the two substrates to each other by a fixed angle of rotation takes place before the determination of the tilting of the two Substrates according to steps c) and d) is carried out. The angle of rotation can in particular assume a value from 0.05° to 10°, preferably from 0.1° to 5°, in particular from 0.2° to 2°. After step d) has been carried out, the renewed intentional rotation of the two substrates relative to one another by the specified angle of rotation can then be reversed by rotating the two substrates relative to one another by the specified angle of rotation in the opposite direction.

In an alternative, particularly preferred embodiment, it can be assumed, which can be confirmed in particular by the shape of the Moiré pattern that can be observed on the imaging optics, that in general there is also a rotation of the two substrates relative to one another in addition to tilting. In this case, the present method can preferably be carried out according to steps a) to d), step e) being able to be carried out in this embodiment after the tilting between the two substrates has already been compensated according to step d). The embodiment described above can only be used in the event that the two substrates happen to be rotated only slightly or not at all, in particular if the angle of rotation is at most 0.5°, at most 0.2°, at most 0.1° and in particular a renewed intentional rotation of the two substrates relative to one another by a specified angle of rotation.

The present method thus enables a fully automatic alignment of a surface of the first substrate, which is often used as a stamp, in which, after the arrangement of the first surface of the first substrate in relation to the second surface of the second substrate, the detection angle can be determined as the first parameter, which is used to compensate in the form first deviations occurring when the first surface of the first substrate is tilted relative to the second surface of the second substrate. The angle of rotation required to rotate the two substrates relative to each other until no moiré pattern is imaged on the imaging optics can be determined as a second parameter that compensates in the form of the twisting of the first surface of the first substrate relative to the Second deviations occurring on the second surface of the second substrate can be used. In the special case where no Moiré pattern occurs because the periodic structures on the two surfaces have exactly the same periodicity, a sweep over the two surfaces can be used. The first parameter and/or the second parameter can thus preferably be transferred to a printer's control software in order to correct the first deviations and/or the second deviations. As a result, manual intervention by a user in the mutual arrangement of the two substrates can be avoided.

• - eine Halterung zur Positionierung eines ersten Substrats beabstandet zu dem zweiten Substrat innerhalb eines Schärfentiefenbereichs eines Objektivs einer Abbildungsoptik;
• - eine Unterlage zur Aufnahme eines zweiten Substrats, wobei die Unterlage und/oder das zweite Substrat eine zweite periodische Struktur aufweist; wobei die Halterung und/oder die Unterlage zur Einstellung einer Verkippung einer ersten Oberfläche des ersten Substrats gegenüber einer zweiten Oberfläche des zweiten Substrats eingerichtet ist,
• - die Abbildungsoptik, die zur Aufnahme eines Moire-Muster aus einer Überlagerung der ersten periodischen Struktur und der zweiten periodischen Struktur eingerichtet; und
• - eine Auswerteeinheit, die zur Bestimmung eines Kippwinkels zwischen der ersten Oberfläche des ersten Substrats und der zweiten Oberfläche des zweiten Substrats nach einem hierin offenbarten Verfahren zur parallelen Ausrichtung einer ersten Oberfläche eines ersten Substrats gegenüber einer zweiten Oberfläche eines zweiten Substrats eingerichtet ist; und
• - eine Steuereinheit, die zur Kompensation einer Verkippung der ersten Oberfläche des ersten Substrats gegenüber der zweiten Oberfläche des zweiten Substrats eingerichtet ist.

In a further aspect, the present invention relates to a device for parallel alignment of a first surface of a first substrate with respect to a second surface of a second substrate. The device includes

• - A holder for positioning a first substrate spaced from the second substrate within a depth of field of a lens imaging optics;
• - A base for receiving a second substrate, wherein the base and / or the second substrate has a second periodic structure; wherein the holder and/or the base is set up to adjust a tilting of a first surface of the first substrate relative to a second surface of the second substrate,
• - The imaging optics, set up for recording a Moiré pattern from a superimposition of the first periodic structure and the second periodic structure; and
• - an evaluation unit which is set up to determine a tilt angle between the first surface of the first substrate and the second surface of the second substrate according to a method disclosed herein for the parallel alignment of a first surface of a first substrate with respect to a second surface of a second substrate; and
• - A control unit which is set up to compensate for a tilting of the first surface of the first substrate relative to the second surface of the second substrate.

In a preferred configuration, the evaluation unit can also be set up to determine a rotation angle between the first substrate and the second substrate, and the control unit can also be set up to compensate for a rotation of the first surface of the first substrate relative to the second surface of the second substrate. In this way, in addition to a tilting of the two substrates relative to one another, a rotation of the two substrates relative to one another, which is generally also present, can be corrected. The functions of the evaluation unit and the control unit can in particular be taken over by the control software of a printer.

In a further preferred embodiment, the device can also include a light source, in particular a polychromatic or a monochromatic light source, which is set up to illuminate the two substrates within the depth of field of the lens of the imaging optics. The light source can preferably be a light-emitting diode. However, other types of light sources are also possible.

In a further preferred embodiment, the device can also include collimator optics, which are set up to parallelize the light emitted by the light source. The collimator optics can preferably be arranged in such a way that the parallelization of the light emitted by the light source preferably takes place before the light impinges on the two substrates arranged within the depth of field of the lens of the imaging optics.

In a further preferred embodiment, the device can also include a beam splitter which is set up in particular for projecting the light emitted by the light source and the light collimated by the collimator optics onto the two substrates arranged within the depth of field of the lens of the imaging optics. Instead of or in addition to the beam splitter, at least one further optical element, in particular at least one converging lens, can be used for this purpose.

In a further preferred embodiment, the at least one lens included in the imaging optics can be designed in the form of a telecentric lens or have a telecentric lens. The term "telecentric lens" refers to an optical lens in which an entrance pupil or an exit pupil of the lens is at infinity. If the entrance pupil is at infinity, the main rays in the object space run parallel to the optical axis. As a result, a beam path that is telecentric on the object side can be used in particular to avoid perspective distortion when detecting an object. In addition, an imaging scale remains the same in the case of axial object displacement, so that an image of the object always appears the same size, regardless of the object distance. The object-side telecentric beam path can have a converging optics, which preferably includes at least one converging lens.

In a further preferred embodiment, the imaging optics can also include an observation screen which is set up in particular to display the Moiré pattern. The observation screen can preferably be selected from a CMOS or a CCD array; however, other types of viewing screens are possible.

In a further preferred embodiment, the imaging optics can also include a collecting optics, which are set up to project the moire pattern onto the observation screen. The collecting optics can preferably comprise at least one collecting lens; however, other types of collection optics are possible.

For further details relating to the present device, reference is made to the description of the method according to the invention.

As used herein, the terms “have”, “have”, “comprise” or “include” or any grammatical variations thereof are used in a non-exclusive manner. Accordingly, these terms can refer both to situations in which, in addition to those caused by them features introduced by terms, no other features are present, or to situations in which one or more other features are present. For example, the phrase "A has B,""A has B,""A includes B," or "A includes B" can both refer to the situation in which there is no other element in A other than B (ie to a situation in which A consists exclusively of B), as well as to the situation in which, in addition to B, there are one or more other elements in A, e.g. element C, elements C and D or even further elements .

Furthermore, it is pointed out that the terms "at least one" and "one or more" as well as grammatical variations of these terms, if they are used in connection with one or more elements or features and are intended to express that the element or feature is provided once or several times can generally only be used once, for example when the feature or element is introduced for the first time. If the feature or element is subsequently mentioned again, the corresponding term “at least one” or “one or more” is usually no longer used, without thereby limiting the possibility that the feature or element can be provided once or more than once.

Furthermore, the terms “preferably”, “particularly”, “for example” or similar terms are used herein in connection with optional features, without alternative embodiments being limited thereby. Thus, features introduced by these terms are optional features and are not intended to limit the scope of the claims, and in particular the independent claims, by these features. Thus, as will be appreciated by those skilled in the art, the invention may be practiced using other configurations. Similarly, features introduced by "in an embodiment of the invention" or by "in an exemplary embodiment of the invention" are understood as optional features without intending to limit alternative configurations or the scope of the independent claims. Furthermore, these introductory expressions are intended to leave untouched all possibilities of combining the features introduced here with other features, be they optional or non-optional features.

Advantages of the Invention

The present method and the proposed device have a number of advantages over methods and devices known from the prior art. While it is relatively easy to compensate for a rotation using methods and devices known from the prior art, as the exemplary embodiments shown below show, these can practically not resolve a tilt in the moiré image, with angles >10° being particularly practical are no longer distinguishable. In contrast to this, the present method and the proposed device make it possible to determine and correctly compensate for any tilt angle.

The present method and the proposed device are non-contact. Damage to or contamination of at least one of the two substrates, in particular the carrier substrate and/or the substrate to be coated, as described above, can thus be avoided.

The present method is fast and can be carried out at any time in situ, in particular by successive rotation and tilting of one of the two substrates in the form of a sweep at fixed times, e.g. before and after each approach of the first substrate to the second substrate. If a defined torsion is set during a lateral movement between two approaches, a movement path and a movement direction defined thereby can also be determined in-situ without contact, in particular from an observation of the moiré pattern, which shows that the moiré fringes during movement represent a running wave.

character list

• 1 eine schematische Darstellung einer bevorzugten Ausführungsform einer erfindungsgemäßen Vorrichtung zur parallelen Ausrichtung einer ersten Oberfläche eines ersten Substrats gegenüber einer zweiten Oberfläche eines zweiten Substrats;
• 2 eine Darstellung von Anordnungen, die das erste Substrat gegenüber dem zweiten Substrat einnehmen kann, insbesondere eine Verdrehung (2A) und eine Verkippung (2B);
• 3 bis 6 jeweils eine Überlagerung einer ersten periodischen Struktur mit einer zweiten periodischen Struktur;
• 7 und 8 einen Vergleich von Moire-Mustern, die für verschiedene Anordnungen des ersten Substrats gegenüber dem zweiten Substrat erzeugt wurden; und
• 9 und 10 jeweils eine schematische Darstellung einer Abhängigkeit eines Nachweiswinkels in Moire-Mustern von einem Kippwinkel bei konstantem Drehwinkel.

Further details and features of the present invention result from the following description of preferred exemplary embodiments, in particular in connection with the dependent claims. The respective features can be implemented individually or in combination with one another. However, the invention is not limited to the exemplary embodiments. The exemplary embodiments are shown schematically in the following figures. In this case, the same reference numerals in the figures designate elements which are the same or have the same function, or elements which correspond to one another in terms of their functions. Show in detail:

• 1 a schematic representation of a preferred embodiment of a device according to the invention for parallel alignment direction of a first surface of a first substrate opposite a second surface of a second substrate;
• 2 a representation of arrangements that can take the first substrate relative to the second substrate, in particular a twist ( 2A ) and a tilt ( 2 B );
• 3 until 6 in each case a superimposition of a first periodic structure with a second periodic structure;
• 7 and 8th a comparison of moiré patterns generated for different arrangements of the first substrate versus the second substrate; and
• 9 and 10 each a schematic representation of a dependence of a detection angle in Moiré patterns on a tilt angle at a constant angle of rotation.

Description of the exemplary embodiments

1 shows a schematic representation of a preferred embodiment of a device 110 according to the invention for the parallel alignment of a first surface 112 of a first substrate 114 with respect to a second surface 116 of a second substrate 118. The in 1 Schematically illustrated device 110 comprises a light source 120 whose emitted light 122 is parallelized via collimator optics 124 and is projected via a beam splitter 126 onto the substrates 114, 118 to be aligned with one another. A polychromatic light source is used here as the light source 120; however, a monochromatic light source can also be used.

The first substrate 114, which can also be referred to as a “carrier substrate” or as a “transfer substrate”, has a first periodic structure 128 on the first surface 112 facing the second substrate 118, via which a transfer image is defined. The second substrate 118 to be coated has in the configuration according to FIG 1 on one of the further surfaces 130 facing away from the first substrate 114, a second periodic structure 132, which is used for Moiré compensation. Alternatively (not shown), the periodic structure 132 can be located on the second surface 116 of the second substrate 118 or on a base 146 described in more detail below. The superimposed image of the two periodic structures 128, 132 generates a moiré pattern (in 1 not shown), which can be imaged and analyzed on an observation screen 136 via imaging optics 134 . The imaging optics 134 can preferably include at least one lens 138, in particular a telecentric lens 140 explained in more detail above, and a converging lens 142. The viewing screen 136 may preferably be selected from a 2D CMOS or a CCD array. However, other types of viewing screens 136 are possible.

To adjust the two substrates 114, 118, an actuator motor is used in this exemplary embodiment, which is set up to align the first substrate 114 and/or the second substrate 118. As in 1 shown schematically, a holder 144 is used to position the first substrate 114 at a distance from the second substrate 118 within a depth of field of the lens 138 of the imaging optics 134, while a base 146 is set up to hold the second substrate 228. The bracket 144 and/or the base 146 can be used to set an in 2 B tilting 154, explained in more detail, of the first surface 112 of the first substrate 114 relative to the second surface 116 of the second substrate 118.

Furthermore, the device 110 comprises an evaluation unit 148, which is used to determine an in 2 B tilt angle φ explained in more detail between the first surface 112 of the first substrate 114 and the second surface 116 of the second substrate 118 . As 1 shows schematically, the evaluation unit 148 can receive information from the observation screen 136 that is suitable for determining the tilt angle φ. Furthermore, evaluation unit 148 can preferably also be used to determine an in 2A angle of rotation α explained in more detail between the first substrate 114 and the second substrate 118 .

Furthermore, the device 110 comprises a control unit 150, which is used to compensate for a 2 B tilting 152, explained in more detail, of the first surface 112 of the first substrate 114 relative to the second surface 116 of the second substrate 118. Furthermore, the control unit 150 can compensate for a likewise in 2A rotation 154 of the first substrate 114 in relation to the second substrate 118 explained in more detail. As 1 shows schematically, the control unit 150 can transmit instructions to actuators (not shown), which can adjust a position of the holder 144 and/or the base 146 in order in this way to define the tilt angle φ and/or the angle of rotation α. The control unit 150 can be included in a printer 156 together with the evaluation unit 148 .

2 FIG. 12 shows arrangements that position the first substrate 114 opposite the second substrate 118. FIG can take. 2A 11 shows a rotation 152 of the first substrate 114 relative to the second substrate 118, with a rotation angle α resulting between the first substrate 114 and the second substrate 118. 2 B shows a tilting 154 of the first surface 112 of the first substrate 114 relative to the second surface 116 of the second substrate 118, with a tilting angle φ between the first surface 112 of the first substrate 114 and the second surface 116 of the second substrate 118 resulting.

3 FIG. 12 schematically shows an overlay 158 of the first periodic structure 128 applied to the first surface 112 3A with the second periodic structure 132 associated with the second surface 116 3B , both surfaces 112, 116 being arranged plane-parallel to one another, as a result of which, as in 3C shown, no moiré pattern can be observed by means of the imaging optics 134 .

4 FIG. 12 schematically shows a further superimposition 160 of the first periodic structure 128 applied to the first surface 112 4A with the second periodic structure 132 associated with the second surface 116 4B , wherein the second periodic structure 132 associated with the second surface 116 is rotated by an angle of rotation α=2° with respect to the first periodic structure 128 associated with the first surface 112, whereby, as in 4C shown, a moiré pattern 162 can be observed by means of the imaging optics 134 .

5 FIG. 12 schematically shows a further overlay 164 of the first periodic structure 128 applied to the first surface 112 5A with the second periodic structure 132 associated with the second surface 116 5B , wherein the second periodic structure 132 associated with the second surface 116 is rotated by an angle of rotation α=10° with respect to the first periodic structure 128 associated with the first surface 112, whereby, as in 5C shown, a further Moire pattern 166 can be observed by means of the imaging optics 134 .

6 FIG. 12 schematically shows a further superimposition 168 of the first periodic structure 128 applied to the first surface 112 6A with the second periodic structure 132 associated with the second surface 116 6B , wherein the second periodic structure 116 assigned to the second surface 118 is tilted by a tilt angle φ=10° in relation to the first periodic structure 128 assigned to the first surface 112, as a result of which, as in 6C shown, a further Moire pattern 170 can be observed by means of the imaging optics 134 .

A comparison of the in 7A again shown moire pattern 170 with a further moire pattern 172 in 7B , recorded at a tilt angle ϕ = 5°, compared to the differences between 4C and 5C , which were recorded at different angles of rotation α = 2° and α = 10°, that the twist 152 between the two periodic structures 128, 132 using moiré patterns 162, 166 can be easily determined and thus the twist 152 between the two associated surfaces 112, 116 of the two substrates 114, 118 is easy to compensate, while only the present inventive method enables a quick and non-contact procedure for determining and compensating for the tilting 154.

For this purpose, the two surfaces 112, 116 of the two substrates 114, 118 simultaneously tilt 154 and rotate 152, so that between the two periodic structures 128, 132 a tilt angle φ=5° and a rotation angle α=5° occurs simultaneously. As a result of this arrangement between the two substrates 114, 118, how 7C shows, by means of the imaging optics 134, another moire pattern 174 can be observed, the structure of which is clearly different from the moire patterns 170, 172 in FIGS 7A and 7B differs.

While the moire pattern is 174 in 8A the moiré pattern 174 7C , which occurs at a tilt angle ϕ = 5° and a rotation angle α = 5°, the moiré pattern 176 in is formed 8B with a tilting angle φ=0° and a rotation angle α=5°, ie there is no tilting 154 here, only twisting 152 . A detailed comparison of the two moiré patterns 174, 176 between the 8A and 8B demonstrates the potential of the method according to the invention. A detection angle δ, which can be assigned to each of the moiré patterns 174, 176, differs due to the respective different tilt angle φ given a constant angle of rotation α. Thus, this comparison between 8A and 8B that the detection angle δ that can be determined from the Moiré pattern 174, 176 is suitable for determining the tilt angle φ at a constant angle of rotation α. From the knowledge of the tilt angle φ obtained in this way, a compensation of the tilting 154 of the first surface 112 of the first substrate 114 in relation to the second surface 116 of the second substrate 118 can finally take place according to the invention.

the 9 and 10 each show a dependency of the detection angle δ on the tilt angle ϕ at a constant angle of rotation α, namely in 9 for a constant angle of rotation δ = 5°, and in 10 for three different constant values of the angle of rotation δ ₁ = 1°, δ ₂ = 2° and δ ₃ = 5°.

From the 9 and 10 It follows that the dependency of the detection angle δ on the tilt angle φ at a constant angle of rotation α can be represented in particular as a 2nd order function in relation to the tilt angle. An extreme value, in particular a global extreme value, for the detection angle δ from the Moire pattern 174, 176 can thus be determined independently of the exact course of the change in the detection angle δ in relation to the tilt angle φ.

How from the 9 and 10 shows, a maximum for the detection angle δ from the Moiré pattern 174, 176 can result in the case of rotations in one direction or a minimum in the case of rotations in the opposite direction.

the inside 10 From the illustrated dependency of the detection angle δ on the tilt angle φ at a constant angle of rotation α, it can also be seen that choosing a lower value for the constant angle of rotation α enables an improvement in the resolution when determining the tilt angle φ from the detection angle δ.

Reference List

110

contraption

112

first surface

114

first substrate

116

second surface

118

second substrate

120

light source

122

emitted light

124

collimator optics

126

beam splitter

128

first periodic structure

130

another surface

132

second periodic structure

134

imaging optics

136

observation screen

138

lens

140

telecentric lens

142

converging lens

144

bracket

146

document

148

evaluation unit

150

control unit

152

twist

154

tilting

156

Printer

158

overlay

160

overlay

162

moiré pattern

164

overlay

166

moiré pattern

168

overlay

170

moiré pattern

172

moiré pattern

174

moiré pattern

176

moiré pattern

178

moiré pattern

Claims (10)

A method for parallel alignment of a first surface (112) of a first substrate (114) with respect to a second surface (116) of a second substrate (118), comprising the steps of: a) positioning a first substrate (114) having a first periodic structure ( 128), and a second substrate (118), to which a second periodic structure (132) is assigned, spaced within a depth of field of a lens (138) of imaging optics (134), wherein a first surface (112) of the first substrate (114 ) has a tilt (154) relative to a second surface (116) of the second substrate (118); b) observing a Moiré pattern (174, 176, 178), which is formed by superimposing the first periodic structure (128) with the second periodic structure (132), by means of the imaging optics (134); c) successively changing a tilt angle φ between the first surface (112) of the first substrate (114) and the second surface (116) of the second substrate (118) while maintaining a rotation angle α between the first substrate (114) and the second substrate ( 118), and determining an extreme value for a detection angle δ dependent on the tilt angle φ from the Moire pattern (174, 176, 178); and d) setting the tilt angle φ between the first surface (112) of the first substrate (114) and the second surface (116) of the second substrate (118) to a value for the tilt angle φ associated with the extreme value for the detection angle δ, whereby the tilting (154) of the first surface (112) of the first substrate (114) relative to the second surface (116) of the second substrate (118) is compensated. Method according to the preceding claim, comprising the following further step: e) successively rotating the first substrate (114) perpendicular to the first surface (112) of the first substrate (114) and/or the second substrate (118) perpendicular to the second surface (116) of the second substrate (118) until by means of the imaging optics (134) no moiré pattern (174, 176, 178) is imaged, as a result of which the first surface (112) of the first substrate (114) is twisted (152) in relation to the second surface (116) of the second substrate (118 ) is compensated. The method of the preceding claim, wherein step e) is performed before step c) or after step d), wherein performing step e) before step c) comprises rotating the first substrate (114) perpendicular to the first surface (112) the first substrate (114) and/or the second substrate (118) perpendicular to the second surface (116) of the second substrate (118) by a rotation angle α > 0 before the execution of step c) and by a rotation angle -α after the Execution of step d) takes place. Method according to the preceding claim, wherein the rotation angle α is fixed at a value of 0.05° to 10°. A method according to any one of the preceding claims, wherein the moiré pattern (174, 176, 178) is formed by - The second substrate (118) is opaque and a, the first substrate (114) facing surface (116) of the second substrate (118) has a second periodic structure (132); or - the second substrate (118) is transparent and a further surface (130) of the second substrate (118) facing away from the first substrate (114) has the second periodic structure (132); - The second substrate (118) is transparent and a base (146), on which the second substrate (118) rests, has the second periodic structure (132). An apparatus (110) for aligning a first surface (112) of a first substrate (114) in parallel with a second surface (116) of a second substrate (118), comprising - A holder (144) for positioning a first substrate (114) at a distance from a second substrate (118) within a depth of field of a lens (138) of imaging optics (134), wherein the first substrate (114) has a first periodic structure (128) having; - A base (146) for receiving the second substrate (118), wherein the second substrate (118) and / or the base (146) has a second periodic structure (132); wherein the holder (144) and/or the base (146) is set up to adjust a tilt (154) of a first surface (112) of the first substrate (114) relative to a second surface (116) of the second substrate (118), - The imaging optics (134) set up to record a Moiré pattern (174, 176, 178) from a superposition of the first periodic structure (128) and the second periodic structure (132); and - An evaluation unit (148), which is set up to determine a tilt angle φ between the first surface (112) of the first substrate (114) and the second surface (116) of the second substrate (118) according to a method according to any one of the preceding claims; and - A control unit (150) which is set up to compensate for the tilting (154) of the first surface (112) of the first substrate (114) relative to the second surface (116) of the second substrate (118). Device (110) according to the preceding claim, wherein the evaluation unit (148) is set up to determine a rotation angle α between the first substrate (114) and the second substrate (118), and wherein the control unit (150) to compensate for a rotation (152 ) of the first substrate (114) opposite to the second substrate (118). Device (110) according to any one of the preceding device claims, further comprising - A light source (120), which is set up to illuminate the first substrate (114) and second substrate (118) arranged within the depth of field of the lens (138) of the imaging optics (134); and or - A collimator optics (124) which is set up for parallelizing the light (122) emitted by the light source (120); and or - A beam splitter (126) which is set up for projecting the light emitted by the light source (120) and collimated by the collimator optics (122) onto the first substrate (114) and the second substrate (118). Device (110) according to one of the preceding device claims, wherein the objective (138) of the imaging optics (134) is or comprises a telecentric objective (140). Device (110) according to one of the preceding device claims, wherein the imaging optics (134) further comprises: - an observation screen (136) for displaying the moiré pattern (174, 176, 178), preferably comprising a CMOS or a CCD array; and - a converging lens (142) for projecting the moiré pattern (174, 176, 178) onto the viewing screen (136).

Images