Abstract
A mark field, having at least two location marks with information for the location of the respective location mark in the mark field, and at least one position mark, which is or can be assigned to one of the location marks. Furthermore, the invention relates to a device for determining X-Y positions of structural features of structures arranged on a substrate, wherein the X-Y positions relative to the mark field, which is fixed with respect to the substrate, can be determined. Furthermore, the invention relates to a corresponding method.
Claims
1. A mark field for use in determining X-Y positions of structural features of structures arranged on a substrate, said mark field comprising: a plurality of marks located on a substrate holder on which the substrate is fixed, the plurality of marks being located over or underneath the structures, each of said marks comprising: one or more location marks containing readable position information enabling a determination of respective locations of the location marks in the mark field, and one or more position marks assigned to one of the location marks, each of the position marks being set in relation to the X-Y positions of the structural features of the structures.
2. The mark field according to claim 1, wherein the location marks and/or position marks are arranged in a matrix with uniform spacings between the location marks and/or the position marks.
3. The mark field according to claim 2, wherein the matrix is a symmetrical matrix.
4. The mark field according to claim 1, wherein adjacent location marks and/or adjacent position marks are arranged equidistantly on the mark field.
5. The mark field according to claim 1, wherein the mark field has at least 10×10 marks.
6. The mark field according to claim 1, wherein spacings between adjacent location marks are smaller than the width and/or height or the diameter of the location marks.
7. The mark field according to claim 6, wherein a ratio between the spacing and the width and/or height or the diameter of the location marks smaller than 1.
8. The mark field according to claim 1, wherein each mark of the mark field is different.
9. The mark field according to claim 8, wherein each mark of the mark field has a different encoding.
10. The mark field according to claim 9, wherein said encoding is a position encoding.
11. The mark field according to claim 1, wherein the location marks have one or more of the following characteristics: QR code, barcode, geometric, character sequence, and image.
12. The mark field according to claim 11, wherein said geometric is a three-dimensional figure.
13. The mark field according to claim 11, wherein the character sequence is a letter sequence and/or a number sequence.
14. The mark field according to claim 13, wherein the number sequence is a binary code.
15. The mark field according to claim 1, wherein the at least two location marks and the at least one position mark are optically measurable and simultaneously optically detectable within a predefined viewing area of an optical system.
16. A device for determining X-Y positions of structural features of structures arranged on a substrate, wherein the X-Y positions can be determined relatively to a mark field fixed with respect to the substrate, said mark field comprising: a plurality of marks located on a substrate holder on which the substrate is fixed, the plurality of marks being located over or underneath the structures, each of said marks comprising: one or more location marks containing readable position information enabling a determination of respective locations of the location marks in the mark field, and one or more position marks assigned to one of the location marks, each of the position marks being set in relation to the X-Y positions of the structural features of the structures.
17. A method for determining X-Y positions of structural features of structures arranged on a substrate, the method comprising: determining, via a computer, the X-Y positions relatively to a mark field fixed with respect to the substrate, said mark field including a plurality of marks located on a substrate holder on which the substrate is fixed, the plurality of marks being located over or underneath the structures, each of said marks including one or more location marks and one or more position marks assigned to one of the location marks the location marks containing readable position information enabling a determination of respective locations of the location marks in the mark field, each of the position marks being set in relation to the X-Y positions of the structural features of the structures.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) FIG. 1a shows a detail view of a first embodiment of a mark according to the invention having a location mark and a position mark,
(2) FIG. 1b shows a detail view of a second embodiment of a mark according to the invention having a location mark and a position mark,
(3) FIG. 2 shows a plan view and a sectional view according to the section line A-A of an embodiment of a mark field carrier according to the invention, having a mark field,
(4) FIG. 3 shows a plan view and a sectional view according to the section line A-A of an embodiment of a substrate holder according to the invention in a first embodiment,
(5) FIG. 4 shows a plan view and a sectional view according to the section line A-A of an embodiment of a substrate holder according to the invention in a second embodiment,
(6) FIG. 5 shows a plan view and a sectional view according to the section line A-A of an embodiment of a substrate holder according to the invention in a third embodiment,
(7) FIG. 6 shows a plan view and a sectional view according to the section line A-A of an embodiment of a substrate holder according to the invention in a fourth embodiment,
(8) FIG. 7 shows a plan view and a sectional view of a substrate according to the invention, having structures and a mark field,
(9) FIG. 8 shows a lateral sectional view of an embodiment of the device according to the invention in a method step of detection according to the invention,
(10) FIG. 9 shows a partial side view of a detection step,
(11) FIG. 10 shows a partial side view of a detection step,
(12) FIG. 11 shows a partial side view of a detection step,
(13) FIG. 12 shows a partial side view of a detection step,
(14) FIG. 13 shows a partial side view of a detection step,
(15) FIG. 14a shows an overlay image created from a detection step at a first position in a first rotational location,
(16) FIG. 14b shows an overlay image created from a detection step at the first position in a second rotational location,
(17) FIG. 15a shows an overlay image created from a detection step at a second position in a first rotational location,
(18) FIG. 15b shows an overlay image created from a detection step at the second position in a second rotational location,
(19) FIG. 16 shows a vector field created according to the invention for illustrating deviations determined according to the invention, and
(20) FIG. 17 shows an illustration of the differential vectors arising.
(21) In the figures, the same components or components with the same function are labelled with the same reference numbers.
DETAILED DESCRIPTION OF THE INVENTION
(22) The FIG. 1a shows a mark 1, comprised of a location mark 2, particularly a QR code and a position mark 3. In a particularly preferred embodiment according to the invention, the location mark 2 is also used as a position mark, so that the position mark 3 is omitted and would be contained in the location mark 2.
(23) The location mark 2 is constructed in such a manner that an, in particular optical, system is able to read information. The exemplary QR code contains the readable position information (1, 11). This means that this location mark is located in the first row and the eleventh columns of a matrix of a mark field 4 shown in FIG. 2.
(24) The FIG. 1b shows a particularly preferred mark 1′, comprised of a location mark 2, particularly a QR code and a position mark 3′. The location mark 2 is smaller in this specific embodiment than the position mark 3′ and is enclosed by the position mark 3, particularly completely. An evaluation algorithm is able to detect the shape or contour of the position mark 3′ and to determine an exact position of the position mark 3′. In the concrete case, the exact position would be the centre of the octagon. The centre of the octagon could for example be found by software in that an algorithm adapts a mathematical octagon to the contour of the octagon from the measured image and determines the centre from the mathematical octagon. Algorithms of this type are known to the person skilled in the art and should not be explained further here.
(25) In the further descriptions of the figures, the mark 1 according to FIG. 1a is used by way of example for further showing the concept according to the invention.
(26) The FIG. 2 shows a plan view and a side view of a mark field carrier 5 having the mark field 4, comprised of a plurality of marks 1, which are placed highly symmetrically to one another in particular. The mark 1 according to FIG. 1a is located at the matrix position (1, 11), as it is located in the first row and the eleventh column in relation to the origin shown of a coordinate system 6 relating to the mark field carrier 5. Counting begins at zero here.
(27) The mark field 4 is preferably located on a mark field carrier surface 5o of the mark field carrier 5. The mark field carrier 5 is preferably transparent, so that the mark field 4 can be detected from a mark field carrier rear side 5r through the mark field carrier 5. The mark field carrier 5 preferably has fixing means 12 in the form of vacuum tracks, with the aid of which a substrate 7 (cf. FIG. 8) can be fixed.
(28) FIG. 3 shows a first embodiment of an, in particular transparent, substrate holder 8, which is constructed as a mark field carrier 5 at the same time. The mark field 4 is then preferably located on the same substrate surface 8o as the fixing means 12. In a more preferred embodiment according to the invention, the substrate holder 5 is non-transparent, wherein the mark field 4 is arranged on the substrate holder rear side 8r.
(29) FIG. 4 shows a second embodiment of the substrate holder 8′. The substrate holder 8′ accommodates the mark field carrier 5, that is to say, by contrast with the first embodiment, is not itself the mark field carrier. The mark field carrier 5 is preferably transparent. The mark field 4 is located on the same mark field carrier surface 5o as the fixing means 12. The mark field carrier 5 is not supported centrally and can therefore bend downwards, in particular owing to gravity, but also due to a force acting from above. Bending of this type would buckle the mark field 4 on the mark field carrier surface 5o and is therefore preferably to be reduced. This is achieved by means of a particularly thick design of the mark field carrier 5.
(30) FIG. 5 shows a third further improved embodiment of the substrate holder 8″. The substrate holder 8″ has struts 10, which support the mark field carrier 5, so that bending is avoided to the greatest extent possible. The struts 10 are preferably inherently transparent.
(31) FIG. 6 shows a fourth further improved embodiment of the substrate holder 8′″. The substrate holder 8′″ has struts 10 having, in particular conically running, passages 14. Mark field carriers 5′, which are constructed as inserts in particular, can be accommodated or are fixed in the passages 14, which mark field carriers have mark fields 4. In this specific embodiment, the fixing means 12 are for example located in the substrate holder 8′″.
(32) In particular, the struts 10 exclusively have mark fields 4, so that no marks are provided in the free regions between the struts 10. The substrate holder 8′″ is therefore constructed in a very filigrane and light manner and can be produced very easily. It has a high rigidity in spite of the lower thickness.
(33) Furthermore, the mark field carriers 5′ and thus the mark fields 4 can be replaced more easily.
(34) FIG. 7 shows a fifth, less preferred embodiment of the mark field carrier 5′″, which is formed by the substrate 7 itself here. On one side, (mark field carrier rear side 5r″) the substrate 7 has structures 11 and the mark field 4 on the opposite side. This specific embodiment only makes sense if one can ensure that the mark field carrier rear side 5r″, on which the mark field 4 is located, is not deformed.
(35) FIG. 8 shows the substrate holder 8′ with the inserted and fixed transparent mark field carrier 5, on which the substrate 7 is fixed to structures 11 by means of the fixing means 12.
(36) A first, in particular upper, optical system 13 detects, with a viewing area (illustrated enlarged), the substrate surface 7o, on which the structures 11 are arranged. The first optical system 13′ is focussed onto the structures 11.
(37) A second optical system 13′, which is calibrated, preferably congruent, with the first optical system 13 in particular, detects the mark field carriers surface 5o with the mark field 4 through the transparent mark field carrier 5. The second optical system 13′ is focussed onto the marks 2.
(38) The detected images are, in particular digitally, overlaid and result in an overlay image, from which the spacings dx and dy of one (or more) structural feature 11c (here: upper left corner of the structure 11) from the highly accurate position mark 3 with respect to an X-Y coordinate system are determined.
(39) In the example shown in FIG. 8, the corners of the structure 11 (structural features 11c) are not congruent with the position mark 3, thus the spacings dx and dy are not equal to zero. Furthermore, the structure 11 is slightly rotated in relation to the reference alignment of the position mark 3.
(40) The location mark 2, which allows information about the rough position, can additionally be detected in the viewing area of the optical systems 13, 13′ or the overlay image.
(41) It is possible to determine the rotational state and/or a deformation of the structure 11 from a detection of a plurality of structural features 11c.
(42) The FIGS. 9 to 13 show further detection steps in different example cases which differ as follows:
(43) FIG. 9: The optical axes of the two optical systems 13 are congruent to one another. Furthermore, the characteristic structural features 11c of the structures 11 are located directly above the position markers 3 relevant for the position measurement. An ideal overlay image results accordingly. A further feature includes the densities of the structures 11 on the substrate surface 7o being identical to the density of the position marks 3 on the mark field carrier surface 5o. A mark field carrier 5 is preferably constructed, which can be used for different substrates 7 with different densities on structures 11.
(44) According to the invention, the density of the marks 1 is in particular higher than the density of the structures 11. Thus, it is ensured that in the region of astructure 11 and/or a structural feature 11c, at least one mark 1 lies in the viewing area of the optical systems 13, 13′.
(45) FIG. 10: The optical axes of the two optical systems 13 are congruent to one another. Furthermore, the characteristic features 11c of the structures 11 are located directly above the position markers 3 relevant for the position measurement. The resultant difference in the overlay image can be traced back exclusively to the displacement between the position marks 3 and the structures 11 and is not based on an optical error. A further feature includes the densities of the structures 11 on the substrate surface 7o not being identical to the density of the position marks 3 on the mark field carrier surface 5o.
(46) It can be seen from the present figure that although there is a translational displacement between the structures 11, more precisely the characteristic features 11c of the structures 11 and the position marks 3, these are uniform for all of the overlay images (shown). That is synonymous with the statement that one would only have to displace the substrate 7 relatively to the mark field carrier 5 in order to obtain the congruence state of FIG. 9 (naturally only for every second structure 11, as the density of the structures in FIG. 10 is only half as large as the density in FIG. 9).
(47) FIG. 11: The optical axes of the two optical systems 13, 13′ are not congruent and not even parallel to one another. Therefore, it cannot be assumed that the characteristic structural features 11c of a structure 11 are congruent with the respective position mark 3 (even if they lie exactly above one another) in the overlay image. The oblique position of the optical axes, just like changes in the thickness of the substrate 7, a wedge error of the substrate 7, etc. lead to the overlay images not being ideal, even under ideal conditions. In order to correct this type of optical errors, (as described above) a rotation by 180° is carried out, a second measurement of all structures is undertaken and the optical error, which is primarily to be traced back to the oblique position of the optical axes, is calculated from the average value of the thus-obtained positions of the characteristic structural features 11c of the structures 11.
(48) FIG. 12: The density of the structures 11 is different from the density of the position marks 3. The characteristic structural features 11c are not congruent to the position marks 3 and the optical axes of the optical systems 13 are neither congruent nor parallel to one another. Due to the elimination of the error, which emerges from the optical axes, according to the description from FIG. 11, an overlay image according to FIG. 10 still remains then.
(49) FIG. 13: This embodiment shows the preferred case according to the invention. In turn, the densities of the structures 11 and the position marks 3 are different. Due to the oblique optical axes, an optical error results in the overlay image, which is calculated by rotation through 180° and a second complete measurement of all structures. Furthermore, the structure 11 is located much too far to the left. It is conceivable that the surface had been distorted by a process and/or that this part has thermally expanded owing to thermal loading. The displacement of the structure 11 therefore no longer has anything to do with the global displacement of all structures 11 in relation to the mark field 4, which can in particular be traced back to the fact that the substrate 7 has experienced a displacement as a whole in relation to the mark field 4. This displacement of the structure 11 is location-specific and immanent. It is of primary importance that the mark field 4 lying therebelow is and remains highly symmetrical.
(50) The following figures are used for further explaining possible sources of errors and the respective measures of the method according to the invention in order to be able to determine and evaluate the sources of errors during the determination.
(51) FIG. 14a shows an overlay image of a structure 11 having a position mark 3 and a location mark 2 at a position (11,1) in a rotational location of 0°. The spacings dx(11,1), 0° and dy(11,1), 0° between the position mark 3 and the characteristic structural feature 11c of the structure 11.
(52) FIG. 14b shows an overlay image of a structure 11 having a position mark 3 and a location mark 2 at a first position (11,1) in a rotational location of 180°. The spacings dx(11,1), 180° and dy(11,1), 180° between the position mark 3 and the characteristic structural feature 11c of the structure 11.
(53) The errors, which result due to the oblique position of the optical axes and other sources of error, can be calculated in the x or y direction from the values dx(11,1),0° and dx(11,1),180° or dy(11,1),0° and dy(11,1),180°, so that the pure offset between the position mark 3 and the characteristic feature 11c of the structure 11 can be determined (calculated).
(54) FIGS. 15a and 15b show a different structure 11 at a second position (12,1), in turn at the two different rotational locations of 0° and 180°. Here also, the errors, which result due to the oblique position of the optical axes and other sources of error, can be calculated in the x or y direction. FIGS. 14 and 15 should show that the horizontal and/or vertical difference between the position marks 3 and the characteristic structural features 11c can deviate very strongly at different positions. These deviations are primarily the result of distortions, expansion, etc.
(55) FIG. 16 shows a vector field. The vector field schematically describes how the structures 11(not drawn in here) are deformed as a function of the location. The size of the arrows increases from the centre outwards. Thus, it is indicated that the structures are stretched towards the edge of the substrate 7. The length of the arrows increases. Thus, it is indicated that the translational displacement increases towards the edge. Here, one is concerned with a classic run-out error. As none of the arrows has a tangential component, no rotational deviation has been determined. In practice, the vector fields determined according to the invention look more complicated.
(56) FIG. 17 shows a schematic illustration of a section of the image overlay of ideal and real structures and position marks in a location. The illustration is used for mathematically showing the relationship of the different values which can be calculated and measured. For the sake of simplicity, the exact illustration of the location marks is dispensed with. The coordinate axes of the coordinate systems of the ideal and real planes had already been adapted to one another, so that all coordinate systems have the same orientation and the same origin as one another. With the exception of the optical error, which has not explicitly been drawn in, but rather is only mentioned in the formula, all other differential vector relationships can be seen. The position of the ideal position mark 3i and the position of the ideal structure 11i are present in the computer. The position of the real position mark 3r and the position of the real structure 11r are measured. According to the invention, the differential vector r.sub.Sr,Mr can be measured. The differential vector r.sub.Si,Mi can be determined from the computer data directly. No measurement is required here. The differential vector r.sub.Mr,Mi can likewise be measured. The differential vector r.sub.Sr,Si, that is to say the deviation of the position of the real structure 11r from the position of the ideal structure 11i, can be calculated from the data obtained.
REFERENCE LIST
(57) 1, 1′ Mark 2 Location mark 3, 3′, 3i, 3r Position mark 4 Mark field 5, 5′, 5″ Mark field carrier 5o, 5o′, 5o″ Mark field carrier surface 5r, 5r″ Mark field carrier rear side 6 Body-fixed coordinate system 7 Substrate 7o Substrate surface 8, 8′, 8″, 8′″ Substrate holder 8o Substrate holder surface 8r Substrate holder rear side 9 Fixing elements 10 Struts 11, 11i, 11r Structures 11c Characteristic structural feature 12 Fixing means 13, 13′ Optical systems 14 Passages
