Device and method for loosening a first substrate

Abstract

A device for detaching a first substrate from a second substrate in a detaching direction (L) with: at least two elements guided crosswise to the detaching direction (L) and in a radial direction (R) to the first substrate for clamping the first substrate crosswise to the detaching direction (L), a substrate holding device for holding the second substrate, and detaching means for detaching the first substrate from the second substrate by moving the first substrate, attached by the clamping elements, in the detaching direction (L) and/or by moving the substrate holding device opposite to the detaching direction (L). In addition, this invention relates to a corresponding method.

Claims

1. A device for detaching a carrier wafer from a product wafer in a detaching direction (L), said device comprising: at least two clamping elements configured to move crosswise to the detaching direction (L) and in a radial direction (R) relative to the carrier wafer to clamp the carrier wafer crosswise to the detaching direction (L), wherein each of the clamping elements includes elastic contour-accommodating elements for accommodating and fixing an edge of the carrier wafer; a substrate holding device for holding the product wafer, and detaching means for detaching the carrier wafer from the product wafer by moving the substrate holding device in a direction opposite to the detaching direction (L).

2. The device according to claim 1, further comprising drive means for moving the at least two clamping elements in the radial direction (R) and/or in the detaching direction (L).

3. The device according to claim 1, wherein said two clamping elements are arranged radially opposite to each other.

4. The device according to claim 1, wherein the clamping elements have an elastic face facing in the radial direction (R) toward the carrier wafer, said elastic face elastically yielding clamping of the carrier wafer.

5. The device according to claim 1, wherein the substrate holding device is a rigid substrate holding device that receives an entire surface of the product wafer.

6. The device according to claim 1, further comprising a clamping element holding device movable in the detaching direction (L), for holding and guiding the clamping elements.

7. The device according to claim 1, further comprising an attaching element for partial attachment of the carrier wafer to the product wafer when detaching the carrier wafer.

8. The device according to claim 7, wherein the partial attachment in an inside area is carried out on an attaching side of the carrier wafer facing away from the product wafer.

9. The device according to claim 7, wherein the attaching element includes attaching means for attaching the carrier wafer to the attaching element.

10. The device according to claim 1, further comprising drive means for moving the at least two clamping elements in the radial direction (R) and the detaching direction (L).

11. The device according to claim 1, further comprising drive means for moving the at least two clamping elements in the radial direction (R).

12. A method for detaching a carrier wafer from a product wafer in a detaching direction (L), said method comprising: holding the product wafer with a substrate holding device; clamping the carrier wafer crosswise to the detaching direction (L), the clamping comprising: guiding at least two clamping elements crosswise to the detaching direction (L) and in a radial direction (R) relative to the carrier wafer, and accommodating and fixing an edge of the carrier wafer using elastic contour-accommodating elements of the clamping elements; and detaching the carrier wafer from the product wafer, the detaching comprising moving the clamping elements in the detaching direction (L) and/or the substrate holding device opposite to the detaching direction (L).

13. The method according to claim 12, further comprising moving the clamping elements in the radial direction (R) and in the detaching direction (L).

14. The method according to claim 12, further comprising partially attaching the carrier wafer to the product wafer by attaching means of an attaching element during detaching the carrier wafer with a counterforce (G.sub.2) directed opposite to the detaching direction (L).

15. The method according to claim 14, wherein the partial attachment in an inside area is carried out on an attaching side of the carrier wafer facing away from the product wafer.

16. The method according to claim 12, further comprising moving the clamping elements in the radial direction (R) and the detaching direction (L).

17. The method according to claim 12, further comprising moving the clamping elements in the radial direction (R).

18. A device for detaching a carrier wafer from a product wafer in a detaching direction (L), said device comprising: a plurality of radially arranged clamping elements, the clamping elements being respectively configured to move crosswise to the detaching direction (L) in a radial direction (R) to clamp corresponding peripheral edges of the carrier wafer, each of the clamping elements including elastic contour-accommodating elements configured to accommodate and fix the corresponding peripheral edge of the carrier wafer; a substrate holding device for holding the product wafer; and detaching means for detaching the carrier wafer from the product wafer by moving the substrate holding device in a direction opposite to the detaching direction (L).

19. The device according to claim 18, further comprising a controller configured to control movement of said clamping elements to clamp said corresponding peripheral edges of the carrier wafer.

20. The device according to claim 19, wherein said controller is further configured to control said movement of said clamping elements individually.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1a a diagrammatic side view of a first embodiment of a clamping element according to the invention,

(2) FIG. 1b a diagrammatic view of the embodiment according to FIG. 1a from below,

(3) FIG. 2a a diagrammatic side view of a second embodiment of a clamping element according to the invention,

(4) FIG. 2b a diagrammatic view of the embodiment according to FIG. 2a from below,

(5) FIG. 3a a diagrammatic side view of a third embodiment of a clamping element according to the invention,

(6) FIG. 3b a diagrammatic view of the embodiment according to FIG. 3a from below,

(7) FIG. 4a a diagrammatic side view of a fourth embodiment of a clamping element according to the invention,

(8) FIG. 4h a diagrammatic view of the embodiment according to FIG. 4a from below,

(9) FIG. 5a a diagrammatic view of an embodiment of a clamping element holding device according to the invention from below in a starting position,

(10) FIG. 5b a diagrammatic view of the embodiment according to FIG. 5a from below in a clamping position,

(11) FIG. 6a a diagrammatic side view of an embodiment of the method according to the invention in a first process step,

(12) FIG. 6b a diagrammatic side view of the embodiment according to FIG. 6a in a second process step,

(13) FIG. 6c a diagrammatic side view of the embodiment according to FIG. 6a in a third process step,

(14) FIG. 6d a diagrammatic side view of the embodiment according FIG. 6a in a fourth process step,

(15) FIG. 6e a diagrammatic side view of the embodiment according to FIG. 6a in a fifth process step,

(16) FIG. 6f a diagrammatic side view of the embodiment according to FIG. 6a in a sixth process step,

(17) FIG. 6g a diagrammatic side view of the embodiment according to FIG. 6a in a seventh process step,

(18) FIG. 6h a diagrammatic side view of the embodiment according to FIG. 6a in an eighth process step;

(19) FIG. 6i a diagrammatic side view of the embodiment according to FIG. 6a in a ninth process step,

(20) FIG. 6j a diagrammatic side view of the embodiment according to FIG. 6a in a tenth process step, and

(21) FIG. 6k a diagrammatic side view of another embodiment according to the invention.

(22) in the figures, components that are the same or that have the same effect are identified with the same reference numbers.

DETAILED DESCRIPTION OF THE INVENTION

(23) The two FIGS. 5a and 5b show the diagrammatic bottom view of a clamping element holding device 9, designed in particular as a clamping ring according to the invention with several clamping systems according to the invention, in particular clamping elements 1, 1, 1, 1. The clamping elements 1, 1, 1, 1 are guided, in particular in a sliding manner, relative to the clamping element holding device 9 and are tightly connected to the clamping ring via drive means 10, in particular motors. The motors are able to run the clamping elements 1, 1, 1, 1 according to the invention in a radial direction R and thus to achieve a clamping of a first substrate 8 that is designed as a carrier substrate. The radial direction R relates to the first substrate 8. The drive means 10 serve to change the position of the clamping elements 1, 1, 1, 1 and to adjust a clamping force F. The drive means 10 are therefore preferably configured in such a way that the clamping force F is adjustable.

(24) During clamping, the clamping elements are oriented laterally in an attaching plane defined by the first substrate 8, in particular an attaching surface 8o of the first substrate 8. The area in which the clamping elements 1, 1, 1, 1 act on the first substrate 8 is referred to as clamping area B. The clamping area B lies in particular in a peripheral area, as in the area of the edge of the first substrate 8.

(25) In a preferred embodiment for the triggering of the clamping elements 1, 1, 1, no motors but rather hydraulic and/or pneumatic control elements are used. As a result, an especially economical and efficient type of design is made possible, since motors can be eliminated. The triggering of the hydraulic and/or pneumatic elements is done with fluids, for example gases and/or liquids, which have a pressure that is higher than 10.sup.5 mbar, preferably higher than 10.sup.3 mbar, more preferably higher than 0.1 bar, most preferably higher than 1 bar, and with utmost preference higher than 2 bar.

(26) FIG. 5a shows the state in which all drive means 10 have run the clamping elements 1, 1, 1, 1 into their starting position relative to the first substrate 8. In order to be able to attach the first substrate 8 of substrate stack 12 that is positioned centrically to the clamping element holding device 9, the clamping elements 1, 1, 1, 1 are run radially (radial direction R) by the drive means 10 to the center of the clamping element holding device 9.

(27) A clamping position, in which it would result in a clamping according to the invention, is depicted in FIG. 5b (without substrate 8). The embodiment according to the invention in accordance with FIGS. 5a and 5b shows the clamping element holding device 9, which can approach the substrate stack 12, in particular from above. In particular, in this case, the clamping element holding device 9 is oriented relative to the substrate stack 12. Drive means for moving the clamping element holding device 9 or the clamping elements 1, 11, 1 in and opposite to the detaching direction are not shown and can be formed in particular by actuators or a robotic arm, which at the same time serve as detaching means in terms of this invention.

(28) The drive means 10 are preferably located in a preferred manner between the clamping ring 9 and the clamping elements 1, 1, 1, 1 according to the invention.

(29) In a quite especially preferred embodiment, many clamping elements 1, 1, 1, 1 according to the invention are attached to the clamping element holding device 9 so that in the clamping position of the clamping elements 1, 1, 1, 1, faces 3s of the contour-accommodating element 3 that point in the direction of a substrate peripheral contour 8k of the substrate 8 form a shell surface that is in particular radially symmetric and/or closed. The shell surface is preferably an inside surface of a cylinder that is comprised of the individual contour-accommodating elements 3.

(30) In the clamping of the first substrate 8, the faces 3s of the contour-accommodating elements 3 are deformed elastically inward, i.e., in the radial direction R (see FIG. 6d). As a result, it is made possible according to the invention to elastically embed the entire substrate peripheral contour 8k, in particular in its entirety, in the contour-accommodating elements 3, and thus to prevent stress peaks on the first substrate 8 before and/or during the detaching process according to the invention. These stress peaks would arise primarily on the substrate peripheral contours 8k of the first substrate 8 that are not covered in their entirety by the contour-accommodating elements 3 according to the invention and in the worst case result in the rupture of the first substrate 8.

(31) FIGS. 6a-6g show a detaching process according to the invention with the embodiment according to the invention. The detaching process is depicted by way of example with the embodiment of the clamping element 1.

(32) FIG. 6a shows a substrate stack 12, comprised of a second substrate 6, a connecting layer 7 that is embodied as an adhesive, and a first substrate 8. The substrate stack 12 is attached to a film 5 that is tightened by a frame 4.

(33) The first substrate 8 has a diameter D. The diameter of the second substrate 6 is in particular approximately equal to the diameter D of the first substrate 8.

(34) In a first step according to the invention in accordance with FIG. 6a, an underside 5u of the film 5 is attached to a substrate holding device 11 (in particular a lower specimen holder designed as a chuck). The attachment is preferably carried out via vacuum strips 14. As an alternative, mechanical, electrostatic, magnetic or adhesive attachments are conceivable. During the detaching of the first substrate 8, the attachment by the substrate holding device 11 applies a corresponding counterforce G.sub.1 to the detaching force F. The counterforce G.sub.1 is preferably to be greater overall than the detaching force F at least at the beginning of the detaching.

(35) In a second step according to the invention in accordance with FIG. 6b, the clamping elements 1 are positioned distributed on the periphery of the substrate stack 12. The clamping elements 1 are preferably attached to a clamping ring, but as an alternative can be attached to the substrate holding device 11.

(36) Corresponding to the embodiment that is used, the clamping elements 1 are able, according to the invention, to execute at least a radial movement as well as a translational movement in and opposite to the detaching direction L. To this end, corresponding drive means are provided.

(37) In order to depict the detaching process according to the invention in as general a manner as possible, a depiction of the clamping element holding device 9 or other attaching means and drive means for the clamping elements 1 was eliminated in FIGS. 6a-6i.

(38) In the second step, one or more stop collars 2s, preferably one stop collar 2s per clamping element 1, can be moved up to the attaching surface 8o of the first substrate 8 that faces away from the second substrate 6. Thus, the clamping elements 1 are oriented in the detaching direction L due to their design without an exact positional control being necessary.

(39) The stop collar 2s is preferably connected via a support 2 to the clamping element 1, in particular molded onto the clamping element 1 in an integral manner. In special embodiments, the stop collar 2s can be eliminated.

(40) The stop collar 2s is preferably adjustable mechanically, pneumatically, hydraulically, electrically, in particular in the detaching direction L, relative to the support 2. In one embodiment, the adjustability of the stop collar 2s in the detaching direction L is eliminated, and a stop collar 2s that is tightly connected to the support 2 is used (see FIG. 1c).

(41) In a third step according to the invention in accordance with FIG. 6c, the clamping elements 1 are lowered to the stop of the stop collar 2 on the attaching surface 8o or positionally-controlled, in particular based on sensor data. The position of the clamping elements 1 can be limited by the contact of the stop collar 2s and the top 8o of the first substrate 8. The stop collar 2s is preferably configured in such a way that it can be positioned in any z-position in the detaching direction L and thus offers the possibility of preventing the contact of the clamping element 1 with the film 5.

(42) Should a clamping device 1, which has no movable stop collar 2s, be used, the stop collar 2s, the support 2 and the contour-accommodating element 3 are preferably constructed in such a way that the film 5 is preferably not touched during the entire process sequence according to the invention.

(43) In a fourth step according to the invention in accordance with FIG. 6d, the clamping elements 1 are run radially toward the center of the first substrate 8 until the substrate peripheral contour 8k has been received from the soft material of the contour-accommodating element 3 up to a penetration depth e. The penetration depth e of the substrate peripheral contour 8k is in particular larger than 1 m and smaller than 3 mm, preferably larger than 10 m and smaller than 1 mm, more preferably larger than 200 m and smaller than 500 m, and with utmost preference larger than 300 m. According to the invention, in particular the ratio between the penetration depth e of the substrate peripheral contour 8k and the thickness d of the first substrate 8 is important. The larger the thickness d of the first substrate 8, the greater the penetration depth e of the substrate peripheral contour 8k is selected. It preferably holds true that the ratio between the penetration depth e of the substrate peripheral contour 8k and the thickness d of the first substrate 8 is smaller than 5, preferably smaller than 1, still more preferably smaller than 1/10, most preferably smaller than 1/100, and all the more preferably smaller than 1/1,000. As an example, a 300 mm carrier wafer is named as a first substrate with an average thickness of 1,000 m (industry-standard average of 775 m). In a ratio of 3 that is preferred according to the invention, this would mean that the penetration depth e of the substrate peripheral contour 8k is 3,000/1,000, and therefore 3 mm. In absolute values, the penetration depth is preferably smaller than 3 mm, more preferably smaller than 1 mm, still more preferably smaller than 0.1 mm, most preferably smaller than 0.01 mm, and all the more preferably smaller than 0.001 mm.

(44) In this case, the face 3s is in particular pressed inward approximately in the middle and deformed in a concave manner at least in sections. This step shows the most important idea according to the invention, namely the gentle accommodation of the substrate peripheral contour 8k by a deformable, soft contour-accommodating element 3. Preferably, the accommodation of the substrate peripheral contour 8k is detected by an electrical measuring apparatus of the device. In particular, force sensors are suitable, which are arranged at a position suitable for the measurement, preferably on the clamping element 1.

(45) After the attachment of the substrate peripheral contour 8k by the contour-accommodating element 3, there are several possibilities for embodying the detaching of the first substrate 8 from the second substrate 6.

(46) The first possibility according to the invention calls for the use of an attaching element 17, in particular in the form of an upper specimen holder, preferably a vacuum specimen holder with vacuum strips 14 for suctioning the first substrate 8.

(47) The attaching element 17 is designed in particular to yield in a flexible manner and/or allows a deformation of the first substrate 8 in an inside area that is arranged inside the clamping area.

(48) The attaching element 17 preferably has a sealing element 15, in particular in the form of a circumferential sealing ring that limits the inside area. Inside the sealing element 15, a vacuum 16 is produced between the attaching element 17 and the first substrate 8. At least during the detaching of the first substrate 8 from the second substrate 6, the vacuum is preferably adjusted to an absolute pressure of less than 1 bar, preferably less than 1 mbar, more preferably less than 10.sup.3 mbar, most preferably less than 10.sup.5 mbar, and with utmost preference less than 10.sup.8 mbar.

(49) The attaching element 17 is movable in particular independently of the clamping elements in and opposite to the detaching direction L. Because of a corresponding control, the attaching element 17 is able to exert a counterforce G.sub.2, in addition to the counterforce G.sub.1 of the substrate holding device 11 to a detaching force F that is exerted by the clamping elements 1, by which the first substrate 8 in the inside area at least at the beginning of the detaching, in particular during the detaching of the clamping area B, is attached to the second substrate 6, in particular in addition.

(50) In a sixth step according to the invention in accordance with FIG. 6f, the clamping elements 1 are pulled in particular upward with the detaching force F accordingly in the detaching direction L. Because of the attachment of the substrate peripheral contour 8k onto the contour-accommodating element 3 and because of the counterforces G.sub.1, G.sub.2 that act on the specimen holder (substrate holding device 11) and the attaching element 17, a bending stress results in the clamping area B. The bending stress results in a detachment of the first substrate 8 from the second substrate 6.

(51) By application of the vacuum 16, the progressive detachment of the first substrate 8 from the connecting layer 7 or from the second substrate 6 is supported by the force exerted by the existing overpressure between the first substrate 8 and the adhesive 7 relative to the vacuum 16.

(52) In a seventh step according to the invention in accordance with FIG. 6g, the first substrate 8 was completely detached from the second substrate 6. In this case, the first substrate 8 is preferably attached by the attaching element 17in addition to the lateral attachment by the clamping element 1. As a result, it is possible, in an additional step, not shown, to loosen the attachment of the clamping elements 1 by their radial movement into the starting position immediately in connection to the detaching of the first substrate 8. The first substrate 8 is then only still attached to the attaching element 17 and can be removed from the device without damage. The attaching element 17 is therefore preferably designed as a chuck.

(53) The second possibility calls for the use of an attaching element 17, whose object exists exclusively in applying the counterforce G.sub.2 to attach parts of the substrate stack 12, in particular the inside area of the first substrate 8, during the detaching process.

(54) The attaching element 17, 17, 17 can have various shapes. It can be in particular: A rounded pin (attaching element 17 according to FIG. 6h). A cylinder (attaching element 17 according to FIG. 6i) with a correspondingly large radius in order to cover a major part of the attaching surface 8o, or A deformable membrane (attaching element 17 according to FIG. 6j), which can be inflated like a balloon and thus a pressure valve that can be controlled in particular on a contact surface to the attaching surface 8o.

(55) One drawback of the last-mentioned embodiments includes the fact that there is no way to attach the first substrate 8 to the attaching element 17, 17, 17, which is provided by the attaching element 17 according to FIGS. 6e-6g.

(56) In particular, the use of a roller as an attaching element 17 according to FIG. 6i, which preferably moves linearly in the direction of movement Q over the first substrate 8 and exerts the counterforce G.sub.2 on the first substrate 8, would be conceivable. Initially only the clamping element 1 (on the right in FIG. 6i) that is arranged in the direction opposite to the direction of movement Q of the roller is preferably raised. According to the invention, sequential individual activation of the clamping elements 1 following in the direction of movement Q of the roller is conceivable. The roller would then act on the first substrate 8 locally along a line, running parallel to the roller axis, to the attaching surface 8o with the counterforce G.sub.2. Thus, it was possible to control the advance of a detaching wave 13 initiated by the clamping elements 1, 1, 1 according to the invention.

(57) A targeted initiation of the detaching wave 13 from any point on the periphery of the first substrate 8 is made possible by the individual triggering according to the invention of the clamping elements 1, 1, 1 and/or a tilting of the clamping element holding device 9 relative to the first substrate 8 and/or the use of the attaching elements 17, 17, 17, 17. The detaching wave 13 is preferably started from a single point. The advancing of the detaching wave 13 is carried out after the initiation with considerably less expenditure of energy.

(58) Primarily when using substrates provided in the inside area with an anti-adhesive layer, it may be advantageous to implement such a bonding wave initiation along the entire periphery of the substrate and only then to further detach the first substrate 8.

(59) In another embodiment according to the invention, the attaching element 17 is designed as a bellows, which can be inflated using compressed air and thus can optionally match the shape of the first substrate 8. In this variant, primarily a gentle and uniform distribution of force of the counterforce G.sub.2 produced by the attaching element 17 occurs.

(60) In another embodiment according to the invention in accordance with FIG. 6k, a second clamping element holding device 9 according to the invention is used as a substrate holding device 11 with additional clamping elements 1 in order to attach the second substrate 6 analogously to the first substrate 8 in the radial direction to a substrate peripheral contour of the second substrate. The additional clamping elements 1 at least partially replace the function of the substrate holding device 11. The clamping element holding device in particular has the shape of a clamping ring.

(61) It is conceivable, for example, that the substrate stack 12 is first mounted on several pins or a platform (not indicated), whose diameter is smaller than the diameter of the second substrate 6. Then, the second substrate 6 is attached by the clamping elements 1 of the second clamping element holding device 9.

(62) It is conceivable in particular that the second substrate 6 in addition rests on the substrate holding device 11 and is attached by the clamping elements 1 of the clamping element holding device 9 (instead of by vacuum strips 14). The clamping elements 1 of the clamping element holding device 9 are manufactured in particular with a very small thickness.

(63) Primarily the disposition of such a substrate stack 12 on several pins provides for the smallest possible contamination of the second substrate 6. This embodiment according to the invention is therefore primarily suitable for the substrate stack 12, whose lower substrate 6 or upper substrate 8 is still thick so that after the detaching process, a corresponding rigidity is provided, so that a fill-surface attachment or support is unnecessary.

(64) According to another preferred embodiment of the invention, not, shown, the detaching process of the first substrate 8 from the second substrate 6 is carried out without aids, such as the attaching elements 17, 17, 17 or the substrate holding device 11, 11. In this case, the first substrate 8 is held by the clamping elements 1, 1, 1, 1 according to the invention after the detaching process.

LIST OF REFERENCE SYMBOLS

(65) 1, 1, 1, 1 Clamping element 2, 2, 2 Support 2s, 2s Stop collar 3, 3 Contour-accommodating element 3s Face 4 Frame 5 Film 5u Underside 6 Second substrate 7 Connecting layer 8 First substrate 8k Substrate peripheral contour 8o Attaching surface 9, 9 Clamping element holding device 10 Drive means 11, 11 Substrate holding device 12 Substrate stack 13 Bonding wave 14 Vacuum strips 15 Seal 17, 17, 17, 17 Attaching element L Detaching direction R Radial direction F Clamping force G.sub.1, G.sub.2 Counterforce B Clamping area e Penetration depth Angular distance Q Direction of movement D Diameter of the first substrate d Thickness of the first substrate