Abstract
A device and a method for the alignment of substrates. The device includes a first substrate holder for receiving a first substrate that has at least two alignment marks, a second substrate holder for receiving a second substrate that has at least two alignment marks, at least one alignment optic for detecting the alignment marks of the first and second substrates, and at least one positioning optic for detecting positioning marks, wherein the alignment marks of the first substrate and the alignment marks of the second substrate can be aligned with one another depending on the positioning marks. The method of alignment includes the steps of fixing the first and second substrates on respective first and second substrate holders, detecting alignment marks on the substrates, detecting positioning marks, and aligning the alignment marks of the substrates with one another in dependence on the positioning marks.
Claims
1. A device for the alignment of a first substrate and a second substrate, said device comprising: a first substrate holder for receiving the first substrate, wherein the first substrate comprises at least two alignment marks; a second substrate holder for receiving the second substrate, wherein the second substrate comprises at least two alignment marks; at least one alignment optic for detecting the alignment marks; and at least one positioning optic for detecting positioning marks, wherein the alignment marks of the first substrate and the alignment marks of the second substrate are alignable with one another depending on the positioning marks.
2. The device according to claim 1, wherein the alignment marks of the first and second substrates are alignable with one another by means of the positioning marks, when one or more of the at least two alignment marks of the first substrate is concealed by the second substrate (2o, 2u) for the at least one alignment optic (6ol, 6or, 6ul, 6ur) and/or when one or more of the at least two alignment marks of the second substrate is concealed by the first substrate for the at least one alignment optic.
3. The device according to claim 1, wherein a positioning mark field is formed by the positioning marks.
4. The device according to claim 1, wherein the positioning marks are formed by a multiplicity of fine-positioning elements.
5. The device according to claim 1, wherein each of said positioning mark is formed differently.
6. The device according claim 1, wherein the positioning marks have one or more of the following shapes: a QR Code, a bar code, a geometrical figure, a character string, and an image.
7. The device according to claim 1, wherein at least one of the first and second substrate holders and/or the at least one positioning optic is moveable in at least two directions.
8. The device according to claim 1, wherein the positioning marks are arranged laterally beside at least one of the first and second substrates.
9. The device according to claim 1, wherein the positioning marks are arranged on at least one of the first and second substrate holders.
10. The device according to claim 1, wherein the positioning marks are arranged on a surface of at least one of the first and second substrate holders.
11. The device according to claim 1, wherein the positioning marks are arranged at a same level as a substrate surface of at least one of the first and second substrates.
12. The device according to claim 1, wherein positions of the alignment marks of the first and second substrates are detectable by the at least one positioning optic during alignment of the alignment marks of the first and second substrates with one another.
13. A method for alignment of the first and second substrates with a device according to claim 1, wherein the method comprises: i) respectively fixing of the first and second substrates on the first and second substrate holder; ii) detecting the alignment marks on the first and second substrates; iii) detecting the positioning marks; iv) aligning the alignment marks of the first and second substrates with one another in dependence on the positioning marks.
14. The method for the alignment of two the first and second substrates according to claim 13, wherein after step iii) a position of the alignment marks and/or a location of the alignment marks relative to one another can be determined.
15. The device according to claim 3, wherein the positioning marks are arranged regularly.
16. The device according to claim 3, the position of different positioning marks, in the positioning mark field formed by the positioning marks, relative to one another is known.
17. The device according to claim 4, wherein the fine-positioning elements are arranged irregularly.
18. The device according to claim 5, wherein the positioning marks have a specific information content.
19. The device according to claim 18, wherein the specific information content is detectable by the positioning optic.
20. The device according to claim 6, wherein the geometrical figure is three-dimensional.
21. The device according to claim 6, wherein the character string is a letter sequence and/or a number sequence.
22. The device according to claim 6, wherein the character string is a binary code.
23. The device according to claim 7, wherein, wherein the at least two directions are x-direction and y-direction.
24. The device according to claim 8, wherein the positioning marks are arranged laterally beside at least one of the first and second substrates such that the alignment marks of the first and second substrates are alignable with one another when the alignment marks of said substrates are concealed for the at least one alignment optic by the other substrate.
25. The device according to claim 12, wherein the positions of the alignment marks of the first and second substrates are continuously detectable by the at least one positioning optic during the alignment of the alignment marks of the first and second substrates with one another.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0127] FIG. 1 shows a first substrate holder according to the invention,
[0128] FIG. 2 shows a second substrate holder according to the invention,
[0129] FIG. 3 shows a third substrate holder according to the invention,
[0130] FIG. 4 shows a fourth substrate holder according to the invention,
[0131] FIG. 5a illustrates a first process step in a first alignment system according to the invention,
[0132] FIG. 5b illustrates a second process step in a first alignment system according to the invention,
[0133] FIG. 5c illustrates a third process step in a first alignment system,
[0134] FIG. 5d illustrates a fourth process step in a first alignment system,
[0135] FIG. 5e illustrates a fifth process step in a first alignment system,
[0136] FIG. 6a illustrates a first process step in a second alignment system according to the invention,
[0137] FIG. 6b illustrates a second process step in a second alignment system,
[0138] FIG. 6c illustrates a third process step in a second alignment system,
[0139] FIG. 6d illustrates a fourth process step in a second alignment system,
[0140] FIG. 6e illustrates a fifth process step in a second alignment system,
[0141] FIG. 7a illustrates a first process step in a third alignment system according to the invention,
[0142] FIG. 7b illustrates a second process step in a third alignment system,
[0143] FIG. 7c illustrates a third process step in a third alignment system,
[0144] FIG. 7d illustrates a fourth process step in a third alignment system,
[0145] FIG. 7e illustrates a fifth process step in a third alignment system,
[0146] FIG. 8a illustrates a first process step of a fine-alignment process and
[0147] FIG. 8b illustrates a second process step of a fine-alignment process.
[0148] Identical components or components with the same function are denoted by the same reference numbers in the figures.
[0149] All the figures represent components and their features solely diagrammatically in a basic, rough manner. The figures are neither true to scale, nor are the features of the component necessarily designed as represented. The figures are therefore to be understood solely as schematic diagrams and their features are to be interpreted functionally under all circumstances.
DETAILED DESCRIPTION OF THE INVENTION
[0150] FIG. 1 shows a first substrate holder 1o, with positioning mark fields 3ol, 3or, comprising a plurality of positioning marks 4ol, 4or, on which a substrate 2o with alignment marks 5ol, 5or has been fixed. Only positioning marks 4or are represented enlarged on the right-hand side. Accordingly, there are positioning marks 4ol on the left-hand side, the enlargement whereof is not represented on account of clarity and transparency. Positioning mark fields 3ol, 3or are located on the substrate holder fixing side, i.e. on the same side as fixed substrate 2o. Accordingly, positioning mark fields 3ol, 3or can be located only outside the fixing region for substrate 2o. Positioning mark fields 3ol, 3or are present in particular along a direction over the entire length of substrate 1, in the present case along the x-direction. It is however again mentioned that, for the adaptation of the type 1 alignment system too, such long positioning mark fields 3ol, 3or are not necessary and they can have a size just like positioning marks 3ol, 3or (see FIG. 2) in the extension of a type 2 alignment system. Since substrate holder 10 of the type 1 alignment system, which is described in the series of FIGS. 4a-4f, covers however further distances, positioning mark fields 3ol, 3or are represented constituted as an additional extension along the entire x-direction. This substrate holder 10 is used for alignment systems of type 1. Substrate holder 10 comprises fixing elements 8, as well as a deformation element 10. The latter are also mentioned and described merely in a rudimentary manner, since they are not of essential importance for the idea.
[0151] FIG. 2 shows a second, preferred substrate holder 1o′, with positioning mark fields 3ol′, 3or′, comprising a plurality of positioning marks 4ol, 4or, on which a substrate 2o with alignment marks 5ol, 5or has been fixed. Only positioning marks 4or are represented enlarged on the right-hand side. Accordingly, there are positioning marks 4ol on the left-hand side, the enlargement whereof is not represented for reasons of clarity and transparency. Positioning mark fields 3ol′, 3or′ are located on a substrate holder fixing side, i.e. on the same side as fixed substrate 2o. Accordingly, positioning mark fields 3ol′, 3or′ can be located only outside the fixing region for substrate 2o. Substrate holder 1o′ preferably also comprises openings 9, which are in particular fully through-going milled slots, oblong holes, holes or drill holes, through which alignment optics 5ol, 5or can view through substrate holder 1o′. Openings 9 in particular simplify the process, which is represented in FIGS. 5a-5e. In particular, the required, mutual displacements of substrate holders 1o′,1u thus become shorter. The process can also be implemented without openings 9, but is then less efficient, because in this case the required, mutual displacements of substrate holders 1o′,1 are somewhat longer. For the sake of completeness, therefore, openings 9 are always shown. This substrate holder 1o′ is used primarily for alignment systems of type 2 and type 3. Positioning mark fields 3ol′, 3or′ are smaller than positioning mark fields 3ol, 3or in FIG. 1. Substrate holder 1o′ also comprises fixing elements 8, as well as a deformation element 10. The latter are also mentioned and described solely in a rudimentary manner, since they are not of essential importance for the idea.
[0152] FIG. 3 shows a third, still more preferred substrate holder 1o″, with a front and a rear positioning mark field 3ov, 3oh comprising a plurality of positioning marks 4o. It can be seen that the connecting line between positioning mark fields 3ov, 3oh does not lie parallel to the connecting line between the two alignment marks 5ol, 5or, positioning mark fields 3ov, 3oh being rotated through 90° with respect to alignment marks 5ol, 5or. A characteristic feature of substrate 1o″ is that alignment marks 5ol, 5or of upper substrate 2o are not located in line with positioning marks 3ov, 3oh, which are therefore denoted with indices v (front) and h (rear). This nomenclature facilitates the explanations in the following descriptions of the figures. Substrate holder 1o″ also comprises fixing means 8, as well as a deformation element 10. These are also mentioned and described solely in a rudimentary manner, since they are not of essential importance for the idea. Second substrate holder 1o″ also comprises openings 9, which allow the alignment optics very close access to the periphery of substrate 2o. This will be important for the method in the subsequently described process.
[0153] FIG. 4 shows a fourth, less preferred substrate holder bow, with a single positioning mark field 3o″, comprising a plurality of positioning marks 4o, on which a substrate 2o with alignment marks 5ol, 5or has been fixed. Positioning mark field 3o″ is located on the substrate holder outer side. Accordingly, positioning mark field 3o″ can be produced over a very large surface area. This substrate holder 1o′″ can be used for all types of alignment system. A drawback with this embodiment is primarily the fact that the depth of focus range of the alignment optics used (not shown) and of the positioning optics (not shown) cannot lie at the same level. The depth of focus ranges are separated from one another at least by height h of substrate holder 10′. The focal planes of alignment marks 5ol, 5or and of positioning marks 4o are thus also correspondingly very distant from one another. Positioning mark field 3o″ does not of course have to extend over the entire substrate outer surface of substrate holder 1o′″, but rather can be localised and smaller. The extension over a very large area is only a further embodiment. Substrate holder 1o′ also comprises fixing means 8, and a deformation element 10. These are also mentioned and described solely in a rudimentary manner, since they are not of essential importance for the idea.
[0154] The following descriptions of the figures serve to illustrate a process, in particular for devices of type 1.
[0155] For the sake of greater clarity, there are no cross-sections through FIGS. 5a-5e.
[0156] FIG. 5a shows a first process step of a first process in a lateral representation (on the left) and in a plan view (on the right). An upper substrate holder 1o, with a positioning mark field 3ol on the left-hand side and a positioning mark field 3or on the right-hand side, moves into a loading position in order to receive and fix a substrate 2o. It would also be conceivable for substrate 2o to be fixed on substrate holder 10 without the latter moving. Accordingly, a robot would have to move substrate 2o into the appropriate position, in which it can be fixed by upper substrate holder 1o. The device in particular comprises two upper alignment optics 6ol, 6or, two lower alignment optics 6ul, 6ur and two lower positioning optics 7ul, 7or. In the plan view, fixing elements 8u can be seen on lower substrate holder 1u, with which a lower substrate 2u (not shown) is fixed in a subsequent process step. Alignment optics 6ol, 6or have already been calibrated with respect to lower alignment optics 6ul, 6ur according to a method from the prior art.
[0157] FIG. 5b shows a second process step of a first process. Substrate holder 1o moves in the x-direction until such time as alignment marks 5ol, 5or are detected by alignment optics 6ul, 6ur and at least one positioning mark 4ol, 4or per positioning mark field 3ol, 3or is detected by positioning optics 7ul, 7ur. Positioning marks 4ol, 4or are now represented in the figures only in abstract form as a rectangle in order to simplify the representation. Since alignment optics 6ul, 6ur and positioning optics 7ul, 7ur are no longer moved, it can be determined at any time by the measurement of positioning marks 4ol, 4or of positioning mark fields 3ol, 3or where alignment marks 5ol, 5or are located relative to the optical axes of alignment optics 6ol, 6or, 6ul, 6ur. It must once again be mentioned that the depth of focus ranges of the optical axes of alignment optics 6ol, 6or, 6ul, 6ur have preferably been calibrated to a focal plane in preceding calibration processes. The point of intersection of the depth of focus ranges of the two left-hand alignment optics 6ol, 6ul represents the zero point for the left-hand side and the point of intersection of the depth of focus ranges of the two right-hand alignment optics 6or, 6ur represents the zero point for the right-hand side of the device.
[0158] FIG. 5c shows a third process step of a first process. Upper substrate holder 1o moves so far that it is no longer in the way of upper alignment optics 6ol, 6or. In particular simultaneously, a lower substrate holder 1u moves into a loading position and is loaded with a lower substrate 2u. Lower substrate holder 1u fixes lower substrate 2u. It would of course be conceivable in this case too for lower substrate holder 1u not to be moved and for lower substrate 2u to be deposited, in particular positioned, by a robot. It is of course also conceivable for lower substrate 2u to have already been loaded onto lower substrate holder 1u.
[0159] FIG. 5d shows a fourth process step of a first process, in which lower substrate holder 1u moves until such time as lower alignment marks 5ul, 5ur are located in the field of vision of upper alignment optics 6ol, 6or. Since upper substrate holder 1o was moved out of the fields of vision of upper alignment optics 6ol, 6or in the previous process step, the substrate surface of substrate 2u can be measured. Once lower substrate holder 1u has been positioned, it is no longer moved.
[0160] FIG. 5e shows a fifth process step of a first process, in which upper substrate holder 1o is again moved back into its initial position. Positioning marks 4ol, 4or of positioning mark fields 3ol, 3or are measured in order to acquire precise knowledge concerning the position of upper alignment marks 5ol, 5or which are in the meantime concealed. The position of lower alignment marks 5ul, 5ur must of course still be known, since lower substrate holder 1u has no longer moved. By viewing positioning marks 4ol, 4or of positioning mark fields 3ol, 3or, it is therefore possible to align left-hand alignment marks 5ol, 5ul and right-hand alignment marks 5or, 5ur by a position displacement of upper substrate holder 1o. Upper substrate holder 1o can thus preferably be moved in more than one degree of freedom. In further process steps, the approach of substrates 2o, 2u towards one another then takes place, as well as their bonding process. These process steps are no longer represented explicitly, since they no longer have anything in particular to do with the idea.
[0161] The following descriptions of the figures serve to represent a process, in particular for devices of type 2. The characteristic feature of type 2 alignment systems consists in the fact that substrate holders 1o, 1u move laterally, in particular crossing over.
[0162] For the sake of better clarity, cross-sections of FIGS. 6a-6e are not shown.
[0163] FIG. 6a shows a first process step of a second process, in which lower substrate holder 1u is displaced to one side, in particular the right-hand side. Left-hand alignment optic 6ul measures a left-hand alignment mark 5ol of upper substrate 2o. At the same time, left-hand positioning optic 7ul measures a left-hand positioning mark 4ol of a left-hand positioning mark field 3ol′.
[0164] FIG. 6b shows a second process step of a second process, in which lower substrate holder 1u is displaced to the opposite, in particular the left-hand, side. The right-hand alignment optic 6ur measures a right-hand alignment mark 5or of upper substrate 2o. At the same time, right-hand positioning optic 7ur measures a right-hand positioning mark 4or of a right-hand positioning mark field 3or′.
[0165] FIG. 6c shows a third process step of a second process, in which lower substrate holder 1u is displaced again into its original starting position. In particular simultaneously, upper substrate holder 1o′ is moved to the right until such time as upper left-hand alignment optic 6ol has a free view through openings 9 onto lower alignment mark 5ul of lower substrate 2u. The position of lower alignment mark 5ul relative to the left-hand optical axis is stored.
[0166] FIG. 6d shows a fourth process step of a second process, in which upper substrate holder 1o′ is moved to the left until such time as upper right-hand alignment optic 6or has a free view through openings 9 onto lower alignment mark 5ur of lower substrate 2u. The position of lower alignment mark 5ur relative to the right-hand optical axis is stored.
[0167] The process steps in FIGS. 5c and 5d presuppose that the lower substrate holder has been moved back into its original position in process step two according to FIG. 5b, such that the two alignment marks 5ul, 5ur are located in the field of vision of alignment optics 6ol, 6or. If this is not the case for at least one of alignment marks 5ul, 5ur, lower substrate 2u must be duly repositioned and process steps three and four are repeated.
[0168] Substrate holder 2u may no longer be moved after this process step.
[0169] FIG. 6e shows a fifth process step of a second process, in which upper substrate holder 1o′ is moved back again into its original position until such time as positioning mark fields 3ol′ 3or′ appear in the fields of vision of lower positioning optics 7ul, 7ur. From this time on, upper alignment marks 5ol, 5or can be aligned with respect to lower alignment marks 5ul, 5ur, whereby the automatic control brings upper substrate holder 1o′ into the correct position by the position measurement by means of positioning marks 4ol, 4or. This process is a fine-adjustment process which is described in greater detail in FIGS. 8a-b for all types of alignment system.
[0170] In further process steps, the approach and the actual bonding process of the two substrates then takes place. These process steps are not described in greater detail, since they are no longer relevant for the idea.
[0171] The processes described in FIGS. 5a-6e for types 1 and 2 are based independently of the idea primarily on the principle of the calibration of all the alignment optics on a focal plane. The optics are no longer moved after the calibration.
[0172] The situation is wholly different in the case of the alignment system of type 3. Here, the lower alignment optics are designed such that they can be moved solely in the z-direction, whereas the upper alignment optics can be moved in the x-, y- and preferably also in the z-direction. Furthermore, the lower substrate holder has only one movement in the z-direction, whereas the upper substrate holder has degrees of freedom in the x-, y- and preferably also in the z-direction as well as about three rotational axes. Accordingly, the idea also has an effect here on the process steps.
[0173] In the following figures, a side view (on the left), along the X-direction, and a front view (on the right), along with the Y-direction, are represented.
[0174] For the sake of greater clarity, cross-sections of FIGS. 7a-7e are shown this time.
[0175] Alignment optics 6ul, 6ur, 6ol, 6or and positioning optics 7uv, 7uh are preferably all able to be positioned, rotated and controlled independently of one another.
[0176] FIG. 7a shows a first process step of a third process. Upper substrate holder 1o″ moves to the left. In particular simultaneously, a left-hand alignment optic 6ul moves in the z-direction upwards, until it has left-hand alignment mark 5ol of upper substrate 2o in its field of vision and depth of focus range. In particular simultaneously, at least one positioning optic 7uv, 7uh also moves upwards, until at least one positioning mark 4o from one of positioning mark fields 3ov, 3oh is visible. It thus becomes possible to associate at least one positioning mark 4o from at least one of positioning mark fields 3ov, 3oh with left-hand alignment mark 5ol. The movement of alignment optic 6u and positioning optics 7uv, 7uh is of course not necessary, if the device is designed such that the depth of focus range can already detect alignment mark 5ol and positioning mark fields 3ov, 3oh.
[0177] FIG. 7b shows a second process step of a third process. Upper substrate holder 1o″ moves to the right. In particular simultaneously, a right-hand alignment optic 6ur moves in the z-direction upwards, until it has right-hand alignment mark 5or of upper substrate 2o in its field of vision and its depth of focus range. In particular simultaneously, at least one positioning optic 7uv, 7uh moves upwards, until at least one positioning mark 4o from one of positioning mark fields 3ov, 3oh is visible. It is conceivable that the two positioning optics 7uv, 7uh are already located in position by means of the first process step. It is also conceivable that only one of positioning optics 7uh, 7uv was connected in the first process step to left-hand alignment optic 6ul and so the correspondingly second positioning optic must now be brought into position. If the embodiment makes use of only one positioning optic 7uv or 7uh, the latter is already in position by means of the first process step and measures a second positioning mark 4o of same positioning mark field 3ov or 3oh. It thus becomes possible to associate at least one further positioning mark 4o with right-hand alignment mark 5or. The movement of alignment optic 6ur and positioning optics 7uv, 7uh is of course not necessary, if the device is designed such that the depth of focus range can already detect alignment mark 5or and positioning mark fields 3ov, 3oh.
[0178] FIG. 7c shows a third process step of a third process. Lower substrate holder 1u moves upwards. In particular simultaneously, upper left-hand alignment optic 6ol moves in, generally, a plurality of directions in order to get lower alignment mark 5ul of lower substrate 2u into the field of vision and the depth of focus range.
[0179] FIG. 7d shows a fourth process step of a third process. Upper substrate holder 1o moves to the left. In particular simultaneously, upper right-hand alignment optic 6or moves in, generally, a plurality of directions in order to get lower alignment mark 5ur of lower substrate 2u into the field of vision.
[0180] FIG. 7e shows a fifth process step of a third process. Upper substrate holder 1o is aligned with respect to lower substrate holder 1u, such that upper alignment marks 5ol, 5or are as congruent as possible with respect to lower alignment marks 5ul, 5ur. The movement of upper substrate holder 1o is checked by at least one of positioning optics 7uv and 7uh, whereby at least one of positioning mark fields 3ov, 3oh is continuously read out and evaluated. In particular, fine positioning by means of pixels is carried out. It is therefore possible for upper substrate 2o to be aligned with respect to lower substrate 2u, although alignment marks 5ul, 5ur, 5ol, 5or are concealed by the respectively opposite substrate and are no longer visible.
[0181] FIG. 8a shows a state in which a positioning mark 4 is visible in the field of vision (left-hand image) of a positioning optic (not shown). An alignment mark 5 was able to be measured at any point in time in the field of vision (right-hand image) of an alignment optic (not shown).
[0182] FIG. 8b shows a state in which a positioning mark 4 is visible in the field of vision (left-hand image) of a positioning optic (not shown), which positioning mark has been displaced by a relative displacement of a substrate holder (not shown) until such time as alignment mark 5 is located in a desired position. For the sake of clarity, the desired position for alignment mark 5 has been selected such that it lies on the optical axis of the alignment optic (not shown). The measurement of positioning mark 4 can take place with pixel precision and is therefore used for the fine positioning.
LIST OF REFERENCE NUMBERS
[0183] 1o, 1o′, 1o″, 1o′″, 1u substrate holder [0184] 2o, 2u substrate [0185] 3ol, 3or, 3ol′, 3or′, 3o″, 3ov, 3oh positioning mark field [0186] 4, 4o, 4ol, 4or, 4oh, 4ov positioning mark [0187] 5, 5ol, 5or, 5ul, 5ur alignment mark [0188] 6ol, 6or, 6ul, 6ur alignment optic [0189] 7ul, 7ur, 7uv, 7uh positioning optic [0190] 8, 8o, 8u fixing elements [0191] 9 openings [0192] 10 deformation element
