DEVICE AND METHOD FOR JOINING SUBSTRATES

Abstract

A method and device for bonding a first substrate to a second substrate at contact surfaces of the substrates.

The method includes the following steps: mounting the first substrate on a first mounting surface of a first substrate holder and mounting the second substrate on a second mounting surface of a second substrate holder, wherein the substrate holders are arranged in a chamber; contacting the contact surfaces at a bond initiation surface; and bonding the first substrate to the second substrate from the bond initiation surface to the centre of the substrates.

Claims

1-7. (canceled)

8. A method for bonding a first substrate to a second substrate at respective contact surfaces of the first and second substrates, said method comprising: mounting the first substrate on a first mounting surface of a first substrate holder and mounting the second substrate on a second mounting surface of a second substrate holder, wherein the first and second substrate holders are arranged in a chamber; contacting the respective contact surfaces of the first and second substrates at a bond initiation surface; and bonding the first substrate to the second substrate from a bond initiation surface to the centre of the first and second substrates.

9. The method according to claim 8, wherein the bond initiation surface is circular.

10. The method according to claim 8, wherein the method further comprises: increasing a chamber pressure in the chamber (i) after the contacting of the respective contact surfaces of the first and second substrates at the bond initiation surface, and/or (ii) during said bonding of the first substrate to the second substrate.

11. The method according to claim 8, wherein the bond initiation surface is arranged at the circumferential edge of at least one of the respective contact surfaces of the first and second substrates.

12. The method according claim 8, wherein: prior to the contacting of the respective contact surfaces of the first and second substrates at the bond initiation surface, a concave deformation of the first substrate takes place with respect to the second substrate.

13. The method according to claim 12, wherein the concave deformation of the first substrate takes place with respect to the second substrate by mounting the first substrate on a correspondingly concavely curved first mounting surface.

14. The method according to claim 8, wherein the bond initiation surface is constructed to run in an annular manner.

15. The method according to claim 14, wherein the bond initiation surface runs in a circular manner.

16. The method according to claim 14, wherein the bond initiation surface runs concentrically to the centre of the first and second substrates.

17. The method according to claim 8, wherein the bond initiation surface has a closed circumference.

18. The method according to claim 8, wherein the first substrate and/or the second substrate are fixed at a rear on the first mounting surface and/or the second mounting surface.

19. The method according to claim 18, wherein the first substrate and/or the second substrate are fixed at a rear on the first mounting surface and/or the second mounting surfaces, exclusively in a region of side edges of the first and second contact surfaces.

20. A device for bonding a first substrate to a second substrate at respective contact surfaces of the first and second substrates, said device comprising: a first mounting surface of a first substrate holder for mounting the first substrate; a second mounting surface of a second substrate holder for mounting the second substrate; a chamber, in which the first and second substrate holders are arranged; means for contacting the respective contact surfaces of the first and second substrates at a bond initiation surface; and means for bonding the first substrate to the second substrate from the bond initiation surface to the centre of the first and second substrates.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0084] FIG. 1a shows a first process step of an embodiment of the method according to the invention,

[0085] FIG. 1b shows a second process step of the embodiment according to FIG. 1a,

[0086] FIG. 1c shows a third process step of the embodiment according to FIG. 1a,

[0087] FIG. 1d shows a fourth process step of the embodiment according to FIG. 1a,

[0088] FIG. 1e shows a fifth process step of the embodiment according to FIG. 1a,

[0089] FIG. 1f shows a sixth process step of the embodiment according to FIG. 1a,

[0090] FIG. 2 shows a first embodiment of a substrate holder according to the invention,

[0091] FIG. 3 shows a second embodiment of a substrate holder according to the invention,

[0092] FIG. 4 shows a third embodiment of a substrate holder according to the invention,

[0093] FIG. 5 shows a fourth embodiment of a substrate holder according to the invention,

[0094] FIG. 6 shows a fifth embodiment of a substrate holder according to the invention,

[0095] FIG. 7 shows a first embodiment of a substrate,

[0096] FIG. 8 shows a second embodiment of the substrate, and

[0097] FIG. 9 shows a third embodiment of the substrate.

[0098] In the figures, the same components or components with the same function are labelled with the same reference numbers.

[0099] All figures are not drawn to scale, in order to simplify the illustration and to facilitate understanding. In particular, the curvatures of the substrates are illustrated too large.

DETAILED DESCRIPTION OF INVENTION

[0100] FIG. 1a shows a first process step, in which a first substrate 2o has been loaded onto a first mounting surface 18o of a first substrate holder 1o and fixed. In particular, at the same time, the fixing of a second substrate 2u onto a second mounting surface 18u of a second substrate holder 1u takes place. The fixing of both substrates 2u, 2o preferably takes place inside a chamber 3. It would also be conceivable, however, that the substrate 2u and/or the substrate 2o are fixed on a substrate holder outside the chamber 3 and then transported with the substrate holder into the chamber 3.

[0101] FIG. 1b shows a second process step, in which an alignment of the two substrates 2u, 2o with respect to one another takes place, particularly an alignment of the contact surfaces 17u, 17o thereof. The alignment may be a coarse and/or a fine alignment. Fine alignment preferably takes place by means of alignment marks (not illustrated, as known per se) and optical elements 9. The alignment preferably takes place in the x and/or y direction (speeds v.sub.x, v.sub.y) and/or in the direction of rotation of the substrates 2u, 2o. The curvature of the upper substrate 2o is illustrated in a very exaggerated manner in the figure. For an optical alignment of the two substrates 2u, 2o with respect to one another, the contact surfaces 17u, 17o may be considered as more or less parallel to one another.

[0102] FIG. 1c shows a third process step, in which a relative convergence of the two substrates 2u, 2o takes place, particularly by means of the relative movement of the two substrate holders 1u, 1o with respect to one another (speed v.sub.z). At the latest, in this process step, an evacuation of the chamber 3 begins, which generates a lowest possible chamber pressure p inside the chamber 3. The generation of the vacuum may however begin even before the third process step and is finished before the substrates 2u, 2o contact (FIG. 1d).

[0103] FIG. 1d shows a fourth process step, in which the concavely curved first substrate 2o is fixed on the second substrate 2u. If the first, concavely curved substrate 2o is located on an upper substrate holder 1o, the first substrate 2o can either contact the second substrate 2u by convergence until contacting or by dropping. Preferably, the contacting takes place initially at a bond initiation surface 10 exclusively. The bond initiation surface 10 is formed by the contact surfaces, between 17u and 17o, of the substrates 2u, 2o at the start of the contacting of the substrates 2u, 2o. The contacting takes place initially along the side edges 2r, 2r of the contact surfaces 17u, 17o, particularly fully.

[0104] FIG. 1e shows a fifth process step, in which the chamber pressure p1 in the chamber 3 is set to be greater than the chamber pressure p0 prevailing directly prior to contacting. Due to the pressure difference, thus created, between a cavity 11, formed by the concave deformation of the first substrate 2o, and the chamber space 12 lying outside the substrates 2u, 2o, an, in particular isotropic, pressure acts on the exposed first substrate 2o and presses it onto the second substrate 2u supported by the second substrate holder.

[0105] FIG. 1f shows a sixth process step, in which the connection, particularly the bond, between the first substrate 2o and the second substrate 2u is produced.

[0106] In the rest of the text, individual embodiments of first substrate holders 1o, 1o, 1o, 1o, 1o are described. Preferably, the first substrate holders 1o, 1o, 1o, 1o, 1o according to the invention are comprised of a plurality of components. The substrate holders 1o, 1o, 1o, 1o, 1o shown are illustrated schematically with the minimum necessary number of components which are important for the illustration of the functions according to the invention. Otherwise, the substrate holders 1o, 1o, 1o, 1o, 1o may have conventional features, which are not illustrated here.

[0107] FIG. 2 shows a first embodiment of the first substrate holder 1o, which is solid. The substrate holder 1o is particularly impermeable for electromagnetic radiation from the UV, the visible and the infrared range. The substrate holder 1o has fixings 7 for fixing the first substrate 2o on the static, concave mounting surface 18o.

[0108] FIG. 3 shows a second embodiment of a substrate holder 1o, which is transparent. Due to the transparency, features, particularly alignment marks, on the substrate can be recognized and/or measured through the substrate holder 1o by means of the optical elements 9.

[0109] FIG. 4 shows a third embodiment of a substrate holder 1o, which has bores 4, through which features of the substrate 2o fixed on the substrate holder 1o can be recognized and/or measured by means of the optical elements 9.

[0110] FIG. 5 shows a fourth embodiment of a substrate holder 1o, which has a material layer 5, which can be, in particular electrically and/or magnetically and/or thermally, connected such that a volume contraction or volume expansion occurs. This volume change takes place predominantly in the cubic micrometre to cubic millimetre range. In spite of the small volume change, the concave mounting surface may be changed as a result.

[0111] The material layer 5 may for example be a magnetorheological, electrorheological or a shape-memory alloy. Shape-memory alloys in particular are able to change the volume and thus the shape of the concave mounting surface 18o due to a thermal induced phase transformation. If the material layer 5 is a magnetorheological or electrorheological material layer 5, corresponding electronic and/or electrotechnical components must be provided in the substrate holder 1o, in order to be able to generate magnetic or electric fields, which lead to a change of the volume of the concave mounting surface 18o due to physical influencing of the material layer 5. These components are not drawn in for reasons of clarity. These are coils or electrodes in particular.

[0112] FIG. 6 shows a fifth embodiment of the substrate holder 1o, which can be used by means of control means 8 for a change of the concave mounting surface 18o. The control means 8 may in particular be a [0113] mechanical control means [0114] pneumatic control means [0115] hydraulic control means [0116] electrical control means, particularly a piezoelectric element.

[0117] In particular, a plurality of control means 8 may be distributed in the substrate holder 1o in order to vary the curvature of the concave mounting surface 18o locally.

[0118] Features of the described different substrate holders 1o, 1o, 1o, 1o, 1o may be combined with one another, in order to create novel substrate holders according to the invention. Thus, it is conceivable that a substrate holder is created, which combines the bores from the substrate holder 1o of FIG. 4 with the material layer 5 of the substrate holder 1o of FIG. 5. These combinations are hereby likewise explicitly disclosed.

[0119] The different substrates, which are used for the processes and embodiments according to the invention, are illustrated in the further figures. They may be located in particular on the upper substrate holder 1o or lower substrate holder 1u. In particular, however, the substrates 2 and 2 are termed supports and are preferably located on the lower substrate holder 1u. In the case of a fusion bond, a substrate 2 would also be found on the lower substrate holder.

[0120] FIG. 7 shows the simplest embodiment of a substrate 2. The substrate 2 is preferably an unstructured or structured wafer 13.

[0121] FIG. 8 shows a substrate 2, comprised of a wafer 13 and an adhesive layer 14. The adhesive layer 14 is preferably a bonding adhesive and is for example applied to the wafer 13 by means of a spin lacquering process.

[0122] FIG. 9 shows a substrate 2, comprised of a film 16, which was stretched onto a frame 15. The film 16 preferably has an adhesive layer 14 on its surface.

REFERENCE LIST

[0123] 1u, 1o Substrate holder [0124] 2, 2u, 2o Substrates [0125] 2r, 2r Side edges [0126] 3 Chamber [0127] 4 Bores [0128] 5 Material layer [0129] 7 Fixings [0130] 8 Control means [0131] 9 Optical elements [0132] 10 Bond initiation surface [0133] 11 Cavity [0134] 12 Chamber space [0135] 13 Wafer [0136] 14 Adhesive layer [0137] 15 Film [0138] 16 Frame [0139] 17u, 17o Contact surfaces [0140] 18u, 18o Mounting surfaces [0141] v.sub.x, v.sub.y, v.sub.z Speeds