Method for bonding substrates

Abstract

A method for bonding a first substrate with a second substrate, characterized in that the first substrate and/or the second substrate is/are thinned before the bonding.

Claims

1. A method for bonding a first substrate to a second substrate, the method comprising: thinning the first substrate and/or the second substrate; prior to or after the thinning, fixing the first substrate and/or the second substrate to surfaces of respective elastically deformable carriers; and after the fixing and the thinning, bonding the first substrate to the second substrate by deforming at least one of the carriers, wherein a frame is disposed on each of the carrier surfaces, wherein an upper surface of the frame defines a carrier attaching surface, wherein each of the fixed first and/or second substrates has a side that faces away the carrier surface, and wherein, relative to the carrier surface, a height of the side of the fixed first and/or second substrates is less than a height of the carrier attaching surface.

2. The method according to claim 1, wherein, during the thinning, the first substrate and/or the second substrate is/are thinned to a thickness of less than 1,000 m.

3. The method according to claim 1, wherein the first substrate and the second substrate are at least partially congruent in shape and/or have similar geometric dimensions.

4. The method according to claim 1, further comprising: aligning the first substrate and the second substrate with one another before the bonding, said aligning based on corresponding alignment markings of the first and second substrates; and pre-attaching the first substrate to the second substrate after the aligning and before the bonding.

5. The method according to claim 1, wherein said elastically deformable carriers are respectively included in substrate attachments to which said first substrate and/or said second substrate are respectively attached prior to or after the thinning, and wherein the substrate attachments respectively have substrate attaching surfaces, the substrate attaching surfaces being configured to respectively attach said first and/or second substrates, and wherein said carrier attaching surfaces respectively surround the substrate attaching surfaces, said carrier attaching surfaces being configured to mutually attach the substrate attachments.

6. The method according to claim 1, wherein the carrier attaching surfaces are magnetized.

7. The method according to claim 1, wherein said carriers are respectively attached to ring-shaped frames.

8. The method according to claim 3, wherein the first substrate and the second substrate are congruent in shape at least in relation to a cross-sectional surface that is parallel to a bonding surface of each of the first and second substrates.

9. The method according to claim 4, wherein the aligning of the first and second substrates is to an alignment accuracy of greater than 100 m.

10. The method according to claim 4, wherein the pre-attaching of the first substrate to the second substrate is performed magnetically.

11. The method according to claim 1, wherein the carriers are respectively stretched over frames of substrate attachments that respectively comprise said carriers.

12. The method according to claim 1, wherein the carriers are respectively comprised of elastic films.

13. The method according to claim 1, wherein the bonding comprises applying a centrically-oriented pressure to at least one of the carriers to respectively bring at least one of the thinned and fixed substrates toward another one of the thinned and fixed substrates, the applying of the pressure serving to deform the at least one of the carriers.

14. The method according to claim 13, wherein the centrically-oriented pressure is applied by pins.

15. The method according to claim 13, wherein the centrically-oriented pressure is applied by mandrels.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further advantages, features and details of the invention follow from the subsequent description of preferred embodiments and based on the drawings; the latter show in diagrammatic view in each case:

(2) FIG. 1a a diagrammatic cross-sectional depiction, not to scale, of a first embodiment of a device according to the invention,

(3) FIG. 1b a diagrammatic cross-sectional depiction, not to scale, of a second embodiment of the device according to the invention,

(4) FIG. 2a a diagrammatic cross-sectional depiction, not to scale, of a first process step of a first embodiment of the process according to the invention,

(5) FIG. 2b a diagrammatic cross-sectional depiction, not to scale, of a second process step of the first embodiment,

(6) FIG. 2c a diagrammatic cross-sectional depiction, not to scale, of a third process step of the first embodiment,

(7) FIG. 3a a diagrammatic cross-sectional depiction, not to scale, of a first process step of a second embodiment of the process according to the invention, and

(8) FIG. 3b a diagrammatic cross-sectional depiction, not to scale, of a second process step of the second embodiment.

(9) In the figures, the same components or components with the same function are identified with the same reference numbers.

DETAILED DESCRIPTION OF THE INVENTION

(10) The first embodiment according to FIG. 1a involves a substrate attachment 1 formed from a frame 2 and a carrier 3 (here, an elastic film) that is stretched over the frame 2. It is also conceivable that the stretched carrier 3 is a very thin, but rigid plate in the unsupported state that therefore cannot be interpreted as film. The carrier 3 can then in particular also be elastically deformed by loading its carrier surface 3o. On its carrier surface 3o, the substrate attachment 1 has a substrate attaching surface 9 (or substrate attaching area) and in particular a ring-shaped carrier attaching surface 8 (or carrier attaching area) that surrounds the substrate attaching surface 9.

(11) The frame 2 and the carrier 3 together form a receiving area for receiving an in particular thinned first substrate 4, whereby a side of the first substrate 4 facing away from the carrier 3 is preferably set back relative to the carrier attaching surface 8.

(12) The back-thinned first substrate 4 is attached to the substrate attaching surface 9 (here a film surface) of the carrier 3 (here, an elastic film) that is stretched over the frame 2. The carrier surface 3o is adhesive for attaching the first substrate 4 and for attaching the carrier 3 to the frame 2.

(13) In the embodiment according to FIG. 1b, an in particular monolithic substrate attachment 1 is shown. The latter has a rigid carrier 3 with a carrier surface 3o, which has a vacuum attachment as an attaching element 5.

(14) The attaching element 5 can have vacuum strips (as shown); instead of this, however, it can also have electrostatic attachments, magnetic attachments, adhesive surfaces, or mechanical clamps. In particular, the attaching elements 5 also act over wide distances/long times in the case of a transport of the carrier 3. When using a vacuum for attaching the first substrate 4, the vacuum can be maintained within a vacuum chamber and/or the vacuum strips by closing a valve 6. In the case of other attachments according to the invention, the valve 6 can be interpreted in general as a control unit that is controlled via a control system. Instead of this, a feed line for electric current would a feed line for electric current would also be conceivable in the case of an electrostatic and/or magnetic attachment.

(15) The layer thickness of the thinned first substrate 4 is small so that a stabilization of the first substrate 4 by a carrier 3, 3 according to the invention is advantageous in order to avoid damage to the first substrate 4.

(16) What is stated above for the first substrate analogously applies for a second substrate 4 or other substrates if the latter are designed identically. Combinations of the described substrate attachments 1, 1 can also be used for the second or other substrates.

(17) In the following figures, the process according to the invention is explained based on two examples, whereby the substrates that are to be bonded (first, second, and some other substrates) and substrate attachments are designed identically in each case. It is conceivable according to the invention to use different substrate attachments and/or substrates for the first substrate 4 and the second substrate 4 or other substrates.

(18) FIG. 2a shows an alignment process in which the two substrates 4, 4 are attached in each case to carriers 3 of the substrate attachments 1 that are arranged on opposite sides and are aligned with one another. The alignment is preferably carried out via an alignment unit (aligner), not shown. The alignment is carried out in a way that is known in the art, preferably between corresponding alignment markings on the substrate surfaces 4o, 4o of the substrates 4, 4.

(19) Since the alignment is carried out on alignment markings of the substrates 4, 4, the substrate attachments 1 can be shifted toward one another. This shifting is normally marginal and negligible, however. In particular, the shifting according to the invention is less than 5 mm, preferably less than 1 mm, even more preferably less than 100 m, most preferably less than 10 m, and all the more preferably less than 1 m. In this connection, it is decisive that the corresponding carrier attaching areas or carrier attaching surfaces 8 lie opposite one another in such a way that an adequate transfer of force for mutual attachment of the substrate attachments 1 is made possible.

(20) FIG. 2b shows a contacting process, in which the surfaces 2o (carrier attaching surfaces 8) of the two frames 2 make contact with one another. The two frames 2 are directly attached to one another in particular by inherent magnetic forces (depicted by magnetic field lines 7). It is also conceivable that the substrate surfaces 4o lie above the surfaces 2o. In this case, the substrate surfaces 4o make contact before the surfaces 2o. The surfaces 2o are independently drawn to one another, in particular by magnetic forces.

(21) In the process step according to FIG. 2c, a contact between the two substrates 4, 4 takes place. The making of contact can be done by any elements that impose force on the substrates 4, 4 in opposite directions, in particular by centric and radially-symmetric pressure elements or by rollers. By imposing force, the elastic carrier 3 is expanded in the direction of the opposite carrier 3. In particular, it is conceivable, as depicted, to deform both carriers 3 against one another. If the substrate surfaces 4o project over the surfaces 2o, a contact of the outer frame 2 is carried out in this process step. In particular in the case of the magnetic frames, the making of contact is done independently by their magnetic attraction.

(22) In FIG. 3a, an alignment process is shown analogously to FIG. 2a with substrate attachments 1 according to FIG. 1b.

(23) In FIG. 3b, a contacting process is depicted, in which the substrate surfaces 4o, 4o of the two substrates 4, 4 make contact with one another before the substrate attachments 1 can come into contact. In this embodiment, the substrate attachments 1 therefore operate without contact. The thus formed substrate stack is attached in particular by inherent magnetic forces of the carrier 3.

(24) According to the invention, at least one of the two substrates 4, 4 is a thinned substrate 4, 4. The bonding process is thus no longer limited to the use of thick, dimensionally-stable substrates.

LIST OF REFERENCE SYMBOLS

(25) 1, 1 Substrate attachment 2 Frame 2o Surface 3, 3 Carrier 3o, 3o Carrier surface 4, 4 Substrate 4o, 4o Substrate surface 5 Attaching element, in particular vacuum attachment 6 Control unit, in particular valve 7 Magnetic field lines 8 Carrier attaching area/carrier attaching surface 9 Substrate attaching surface