Flexible substrate holder, device and method for detaching a first substrate

Abstract

A flexible substrate mount for holding a first substrate when the first substrate is being detached from a second substrate, and detachment means for debonding of the second substrate by bending the first substrate. Furthermore, this invention relates to a device for detaching a first substrate from a second substrate in one detachment direction (L) with the following features: a substrate mount for holding the first substrate, said first substrate mount being flexible in the detachment direction (L), a substrate mount for holding the second substrate and detachment means for the debonding of the first substrate from the second substrate as the first substrate bends, and a method of using the same.

Claims

1. A method for processing first and second substrates, said method comprising: providing the first and second substrates as a bonded pair, wherein the first and second substrates are directly bonded together in a fusion bonding process by means of van der Waals forces, said bonded pair not having been subjected to annealing; holding the second substrate with a second substrate mount; holding the first substrate with a first substrate mount which is flexible in a detachment direction (L) for bending of the first substrate, wherein the detachment direction (L) is generally normal to a planar surface of the second substrate; debonding the first substrate from the second substrate in the detachment direction (L), wherein one or more forces are applied to overcome the van der Waals forces of the fusion bonding process, said step of debonding includes bending the first substrate, wherein the step of debonding the first substrate from the second substrate takes place after a bonding of the first substrate to the second substrate by means of the van der Waals forces, but prior to heating to a temperature at which a permanent bond is formed between substrates; and at least one of the first substrate and the second substrate subjected to the debonding is permanently bonded to another substrate by heating to a temperature at which the substrates permanently bond to each other.

2. The method as claimed in claim 1, wherein the step of debonding includes applying the one or more forces to overcome a bond strength of more than 0.2 J/m.sup.2 between the first substrate and the second substrate.

3. The method as claimed in claim 2, wherein the method further comprises: examining the bonded pair of the first and second substrates prior to debonding to determine a quality criteria, wherein the step of debonding the first and second substrates is performed only if the quality criteria fails to meet a defined criteria.

4. The method as claimed in claim 3, wherein the quality criteria include one or more of the following: physical bond strength, chemical bond strength, calibration accuracy of the first and second substrates to one another, and blanket bond interface.

5. The method as claimed in claim 1, wherein the method further comprises: examining the bonded pair of the first and second substrates prior to debonding to determine a quality criteria, wherein the step of debonding the first and second substrates is performed only if the quality criteria fails to meet a defined criteria.

6. The method as claimed in claim 5, wherein the quality criteria include one or more of the following: physical bond strength, chemical bond strength, calibration accuracy of the first and second substrates to one another, and blanket bond interface.

7. The method as claimed in claim 1, wherein the step of debonding further comprises: applying at least one tensile force acting on the periphery of the second substrate mount, and applying at least one opposing force (G) against the at least one tensile force, the at least one opposing force (G) acting on the periphery of the first substrate mount to produce detachment moments along a detachment front between the first and second substrates.

8. The method as claimed in claim 1, wherein the step of debonding further comprises: applying at least one tensile force to the second substrate mount in the detachment direction (L), and applying at least one opposing force to the first substrate mount in a direction generally opposite to said at least one tensile force.

9. The method as claimed in claim 1, wherein the step of debonding further comprises: applying at least one tensile force to the second substrate mount in a first direction; and applying at least one opposing force to the first substrate mount in a second direction that is generally opposite to the first direction, wherein the first substrate mounted to the first substrate mount bends in the detachment direction (L) to detach the first substrate from the second substrate.

10. The method as claimed in claim 1, wherein the method further comprises: adjusting a diameter (D.sub.k) of an open ring of the first substrate mount to receive the first substrate.

11. A method of using a flexible first substrate mount to process first and second substrates, the method comprising: providing the first and second substrates as a bonded pair, wherein the first and second substrates are directly bonded together in a fusion bonding process by means of van der Waals forces, said bonded pair not having been subjected to annealing; holding the second substrate with a second substrate mount; holding the first substrate with the first substrate mount which is flexible in a detachment direction (L) for bending of the first substrate, wherein the detachment direction (L) is generally normal to a planar surface of the second substrate; debonding the first substrate from the second substrate in the detachment direction (L) by applying one or more forces to overcome the van der Waals forces of the fusion bonding process, said step of debonding includes bending the first substrate by flexing the first substrate mount in the detachment direction (L), wherein the step of debonding the first substrate from the second substrate takes place after a bonding of the first substrate to the second substrate by means of the van der Waals forces, but prior to heating to a temperature at which a permanent bond is formed between substrates; and at least one of the first substrate and the second substrate subjected to the debonding is permanently bonded to another substrate by heating to a temperature at which the substrates permanently bond to each other.

12. The method as claimed in claim 11, wherein the step of debonding includes applying one or more forces to overcome a bond strength between the first and second substrate of more than 0.2 J/m.sup.2 between the first substrate and the second substrate.

13. The method as claimed in claim 12, wherein the method further comprises: examining the bonded pair of the first and second substrates prior to debonding to determine a quality criteria, wherein the step of debonding the first and second substrates is performed only if the quality criteria fails to meet a defined criteria.

14. The method as claimed in claim 13, wherein the quality criteria include one or more of the following: physical bond strength, chemical bond strength, calibration accuracy of the first and second substrates to one another, and blanket bond interface.

15. The method as claimed in claim 11, wherein the method further comprises: examining the bonded pair of the first and second substrates prior to debonding to determine a quality criteria, wherein the step of debonding the first and second substrates is performed only if the quality criteria fails to meet a defined criteria.

16. The method as claimed in claim 15, wherein the quality criteria include one or more of the following: physical bond strength, chemical bond strength, calibration accuracy of the first and second substrates to one another, and blanket bond interface.

17. The method as claimed in claim 11, wherein the method further comprises: adjusting a diameter (D.sub.k) of an open ring of the first substrate mount to receive the first substrate.

18. A method for detaching a first substrate from a second substrate, said method comprising: providing the first and second substrates as a bonded pair, wherein the first and second substrates are directly bonded together in a fusion bonding process by means of van der Waals forces, said bonded pair not having been subjected to annealing; holding the second substrate with a second substrate mount; holding the first substrate with a first substrate mount which is flexible in a detachment direction (L) for bending of the first substrate, wherein the detachment direction (L) is generally normal to a planar surface of the second substrate; and examining the bonded pair of the first and second substrates to determine a quality criteria; if it is determined that the quality criteria meets a defined criteria, then heating the first and second substrates to a temperature at which a permanent bond is formed between the first and second substrates, and if it is determined that the quality criteria fails to meet the defined criteria, then debonding the first substrate from the second substrate in the detachment direction (L), said debonding including application of one or more forces to overcome the van der Waals forces of the fusion bonding process, wherein debonding of the first substrate from the second substrate takes place after a bonding of the first substrate to the second substrate by means of the van der Waals forces, but prior to heating to a temperature at which a permanent bond is formed between the substrates.

19. The method as claimed in claim 18, wherein the quality criteria include one or more of the following: physical bond strength, chemical bond strength, calibration accuracy of the first and second substrates to one another, and blanket bond interface.

20. The method as claimed in claim 18, wherein if it is determined that the quality criteria has met the defined criteria, then permanently bonding the first substrate to the second substrate by heating the first and second substrates to a temperature at which first and second substrates permanently bond to each other.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a plan view of the substrate mount as claimed in the invention with a cutting line A-A,

(2) FIG. 2 shows a cross sectional view of the substrate mount according to cutting line A-A from FIG. 1,

(3) FIG. 3 shows a view of the substrate mount according to FIG. 1 from underneath,

(4) FIG. 4 shows a detailed view of detail E from FIG. 2,

(5) FIG. 5a shows a side view of a stack of a first substrate, the interconnection layer and a second substrate,

(6) FIG. 5b shows a plan view of a stack of the first substrate, the interconnection layer and a second substrate,

(7) FIG. 6 shows a detail view analogously to FIG. 4 with a first embodiment of the substrate mount,

(8) FIG. 7 shows a detail view analogously to FIG. 4 with a second embodiment of the substrate mount,

(9) FIG. 8 shows a stack fixed on a film frame,

(10) FIGS. 9a-9d shows a device, as claimed in the invention, according to a first embodiment with four method steps, as claimed in the invention and

(11) FIGS. 10a-10d show a second embodiment of the device, as claimed in the invention, with four method steps.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

(12) The same components, or components with the same action, are identified in the figures with the same reference numbers.

(13) FIG. 1 shows a substrate mount 1 which can be used semiautomatically, in which the accommodation of a first substrate 13 (here: more stable carrier substrate) takes place manually by the substrate mount 1. The substrate mount 1 is used for debonding the first substrate 13 from a second substrate 11 (here: product substrate) which is connected by an interconnection layer 12 to the first substrate 13.

(14) The substrate mount 1 is comprised of a grip 2 located on a peripheral section 26 and a ring 3 which is opened opposite the grip 2. On the opening 3o of the ring 3 on the opposite ends 24, 24′ of the ring 3 there are spacers 25 for adjusting the distance A between the ends 24, 24′. An inside diameter D.sub.i and an outside diameter D.sub.a of the ring 3 can be adjusted by setting the distance A. The spacers 25 in this exemplary embodiment are comprised of levers 4, 5, the lever 4 being placed on the end 24 and the lever 5 on the end 24′. The levers 4, 5 are penetrated by actuating elements 14 which can be operated manually. Automatic implementation of the above-described manual kinematics is conceivable as claimed in the invention.

(15) The grip 2 is attached to the ring 3 by fixing elements 10, namely, screws. The material of the ring 3 as claimed in the invention for a given geometry (ring height H, ring width B, outside diameter D.sub.a, inside diameter D.sub.i) should be chosen such that the ring 3 can be elastically bent by the spacers 25, against its force which is caused by the bending stiffness.

(16) The ring 3 has a peripheral shoulder 7 which projects from a ring offset 6 and forms a step 9. The step 9 runs in a z-shape with an inner angle 45°<I<90°, especially <80°, preferably <70° which is pointed toward the middle of the ring and thus forms a peripheral wall bevel 17 which ends on a sharp inner edge 8. The inner edge 8 is at the same time a component of a face surface 7s of the peripheral shoulder 7, which surface 7s runs parallel to the ring offset 6. The end, i.e. face, surface 7s is equidistant to the ring offset 6 with a distance M. As best seen in FIG. 7, the distance M is at maximum slightly larger (especially larger by the thickness of the interconnection layer 12) than the thickness d of the first substrate 13. Preferably, the distance M as in FIG. 6 is chosen such that it is smaller than the thickness d of the first substrate 13. Preferably, the distance M is at least half as large as the thickness d of the first substrate 13.

(17) The spacers 25 can increase a diameter D.sub.k for holding the first substrate 13, which diameter D.sub.k is formed by the inner edge 8 and which lies between the inside diameter D.sub.i and the outside diameter D.sub.a until the first substrate 13 can be inserted through an opening formed on the inside edge 8 (diameter D.sub.k) as far as the ring offset 6. Then the diameter D.sub.k is again reduced by the spacers 25 until one peripheral edge 13u of the first substrate 13 adjoins the bevel 17 of the peripheral shoulder 7 and is fixed by the latter. Thus, the first substrate 13 is held by the flexible substrate mount 1. The holding takes place more or less by clamping and/or form-fit. For clamping of the first substrate 13 on the bevel 17, there can be dynamometer means for controlling the squeezing, especially on the actuating means 14.

(18) The second substrate 11 (here: product substrate) is attached to the substrate mount 1 only via the interconnection layer 12. There is no direct contact between the substrate mount 1 and the second substrate 11. When avoiding contact between the substrate mount 1 and the second substrate 11, the second substrate 11 is most heavily protected and contamination or damage is essentially precluded.

(19) The second substrate 11 with the interconnection layer 12 and the first substrate 13 form a stack 19 (first substrate-second substrate-combination). Likewise, this invention is suitable for a combination of the first substrate and second substrate without an interposed interconnection layer, especially for so-called prebonds in which the wafers adhere to one another especially by means of van der Waals forces.

(20) The sharp inner edge 8 is used in the fixing of the stack 19 on the substrate mount 1 in the embodiment shown in FIG. 7. At the same time, the sharp inner edge 8 is used as separating means or for initiation of debanding by the tip of the inner edge 8 on the peripheral edge of the interconnection layer 12 penetrating into the interconnection layer 12.

(21) In a use for substrate pairs without interconnection layer 12, especially for fusion-bonded wafers, the interconnection layer 12 described here is the boundary surface (on which the van der Waals forces act) between the substrate pair.

(22) The substrate mount 1 almost completely surrounds the first substrate 13, except for the ring opening 3o.

(23) FIG. 8 shows the stack 19 on a film frame 23, the second substrate 11 being connected to a film 21 which is connected to the film frame 23, the stack 19, the film frame 23 and the film 21 forming a film frame combination 20.

(24) The first substrate 13 can be pulled off the second substrate 11 by means of the grip 2 and by fixing, i.e. holding, of the second substrate 11 or the film frame 23. The tensile force is applied by the unilateral arrangement of the grip 2 laterally on the first substrate 13, in other words, on the peripheral section 26. Initiated by the penetration of the inner edge 8 into the interconnection layer 12, the first substrate 13 is slowly debonded with deformation of the first substrate 13 and of the ring 3 (against its force generated by the bending stiffness) proceeding from the peripheral section 26 to the opposing side. In doing so, a detachment front migrates from the peripheral section 26 up to the opposite side of the first substrate 13 through the interconnection layer 12. Along the detachment front, defined torques act accordingly, depending on the distance of the detachment front from the grip 2 and the detachment force which has been applied to the grip 2.

(25) In automated form, this is shown in a first embodiment in FIGS. 9a to 9d and in a second embodiment in FIGS. 10a to 10d, which are detailed below.

(26) The use of the above-described (first) substrate mount 1 for holding the first substrate 13 in a form suitable for automation is common to the two embodiments.

(27) One important inventive aspect is that at the start of debonding, therefore in the initiation of the debonding, there should be especially careful treatment, especially by implementation of a mechanical partial solution of the interconnection layer on the periphery or on its edge.

(28) FIGS. 9 and 10 each show a base 27 and a rack 22. The rack 22 is set up on the base 27 for providing a stable base structure and for attachment of other components of the device as claimed in the invention, which is described below. On the rack 22 and/or the base 27, between a cover 22d of the rack 22 and a bottom 27b formed by the base 27, there are drive means 15′ for translational movement (especially driven) of the (first) substrate mount 1 or of peripheral sections of the substrate mount 1 and drive means 15 for translational movement (especially driven) of a second substrate mount 18 (receiver) which holds the stack 19 or the film frame combination 20. The drive means 15′ can have a trip-free mechanism in the translation direction, formed by a movable bearing.

(29) The substrate mount 18 in the two embodiments according to FIG. 9 and FIG. 10 can be moved in translation in one detachment direction L, therefore up and/or down in the plane of the drawings. The drive means 15 for driving the substrate mount 18 can be moved especially synchronously, preferably driven by motors which are controlled by a central control means, such as stepping motors.

(30) In the embodiment according to FIG. 9, for the substrate mount 1 there is only one drive means 15′ on the side of the substrate mount 1 opposite the peripheral section 26, while on the peripheral section 26 there is a spherical plane bearing 16, wherein the substrate mount 1 can be pivoted around the spherical plane bearing 16 but is fixed in the detachment direction L. Thus, the sequence of the method is as follows.

(31) In the method step shown in FIG. 9a, the substrate mount 1 which is suitable for the film frame combination 20, especially the first substrate 13, is attached to the upper drive means 15′ and the spherical plane bearing 16. At the same time, beforehand or subsequently the film frame combination 20 is fixed on the substrate mount 18, especially by application of a vacuum. The substrate mount 18 can be moved by the drive means 15 in the detachment direction L.

(32) As claimed in the invention, it is alternatively conceivable that on the periphery of the substrate mount 1 there are several, especially two drive means 15′ on one side and several, especially two spherical plane bearings 16 on the opposite side.

(33) The substrate mount 1 can be fixed, i.e. attached, on the drive means 15′ and the spherical plane bearing 16 by holding means 28 which are located on the ring periphery 3u. The substrate mount 18 can be fixed, i.e. attached, by holding means 29 on the drive means 15.

(34) Then the substrate mount 18 is moved into the position which is shown in FIG. 9b (i.e., in the detachment direction L toward the substrate mount 1) by the drive means 15 executing a synchronous translation movement of the substrate mount 18 until the first substrate 13 with its top 13o adjoins the ring offset 6. The control can take place via the central control means, the meeting of the first substrate 13 with the ring offset 6 being recognized by dynamometer means which are integrated into the substrate mount 18. Preferably on the periphery of the substrate mount 18, there is provided a number n of force transducers distributed at an angular distance of 360°/n.

(35) So that the first substrate 13 can be accommodated in the substrate mount 1, the diameter D.sub.k must be matched accordingly beforehand to the inside edge 8 of the ring 3 so that the first substrate 13 with its outer contour (especially circular with a diameter D.sub.t) can be received into the substrate mount 1. The inside diameter D.sub.i in the accommodation of the first substrate 13 is smaller than the diameter D.sub.t of the first substrate 13 so that the first substrate 13 does not slip through. As soon as the position which is shown in FIG. 9b is reached, the inside diameter D.sub.i can be reduced until the first substrate 13 is fixed in the substrate mount 1 (see FIGS. 6 and 7), i.e., adjoins the wall bevel 17.

(36) As soon as the position which is shown in FIG. 9b has been reached, the upper fixable drive means 15′ is released so that it has a degree of freedom in the detachment direction L and the side of the substrate mount 1 attached to the drive means 15′ can move freely in the detachment direction L. In this embodiment, the drive means 15′ is made drive-less. But a control of the motion by a central control means is also conceivable, as claimed in the invention, so that the drive means 15′ is made, not passive (as in the preferred embodiment), but active.

(37) Then on the two drive means 15, which are provided oppositely on the substrate mount 18, a driving force F.sub.1 (tensile force) which is pointed away from the substrate mount 1 and a driving force F.sub.2 (tensile force) which is especially identical to the driving force F.sub.1 are applied to the substrate mount 18 especially synchronously for debonding of the first substrate 13 which is fixed on the substrate mount 1 from the second substrate 11.

(38) There is an opposing force G (or several opposing forces G if there are several spherical plane bearings 16) on the spherical plane bearing 16 acting opposite the driving forces F.sub.1 and F.sub.2 and especially parallel to them.

(39) In this way, the debonding process which has been initiated from the inner edge 8 is continued, wherein a detachment front runs with increasing bending of the substrate mount 1 and of the first substrate 13 from the spherical plane bearing 16 to the opposite the side of the substrate mount 1. Along the detachment front, in equilibrium with the driving forces F.sub.1 and F.sub.2 as well as the opposing force G (caused by the connecting force of the interconnection layer 12), torques act as detachment moments K.sub.1 to K.sub.n which are distributed infinitesimally along the detachment front.

(40) In the position which is shown in FIG. 9c, the first substrate 13 is debonded by more than half, the debonding taking place by both the first substrate 13 and also the substrate mount 1 deforming (against the bending strength of the substrate mount 1 and of the first substrate 13).

(41) In the position which is shown in FIG. 9d, the first substrate 13 is debonded completely from the second substrate 11. The interconnection layer 12 in the figure adheres to the second substrate 11, but can also adhere partially or completely to the first substrate 13.

(42) During the debonding, the substrate mount 1 bends and the first substrate 13 bends by a (average, especially measured at half debonding of the first substrate 13 from the second substrate 11) bending angle 1°<W<45°, especially W<35°, preferably about 6°.

(43) In the second embodiment as shown in FIGS. 10a to 10d, instead of the drive means 15′, there is a spherical plane bearing 16 on the substrate mount 1 so that the substrate mount 1 is fixed on the peripheral sections 26 and an opposite peripheral section 26′ (therefore where the spherical plane bearings 16 are attached to holding means 28 of the substrate mount 1) in the detachment direction L (as claimed in the invention there can be several spherical plane bearings 16 on the periphery of the substrate mount 1). In sections between the peripheral sections 26, the substrate mount 1 can move within the framework of its flexibility against the bending stiffness. When driving forces are applied in the method step according to 10c, a detachment front arises which runs essentially concentrically (rippled) from the periphery of the interconnection layer 12 toward the middle of the interconnection layer 12. In doing so, the initiation by the inner edge 8 of the substrate mount plays an important part for overcoming the initial connecting force of the interconnection layer 12.

(44) The detachment moments K.sub.1 to K.sub.n in the embodiment according to FIGS. 10a to 10d as the detachment front advances act primarily on a (rippled) circular section along the detachment front. While the bending angle W according to FIG. 9c is measured [on] the side edge opposite the spherical plain bearing, the bending angle W′ is measured from the center of the first substrate 13 to the edge due to the detachment force K acting from all sides on the periphery. The bending angle W′ in this case, due to the shorter distance, is accordingly smaller to the extent the material of the substrate mount 1 and of the first substrate 2, as well as their dimensions, are otherwise identical. By reducing the ring width B and/or the ring height H, the bending stiffness of the ring 3 can be reduced so that the bending angle W′ would increase.

REFERENCE NUMBER LIST

(45) 1 first substrate mount 2 grip 3 ring 3o opening 3u ring periphery 4 lever 5 lever 6 ring offset 7 peripheral shoulder 7s end face 8 inner edge 9 step 10 fixing means 11 second substrate 12 interconnection layer 13 first substrate 13o top 13u peripheral edge 14 actuating elements 15, 15′ drive means 16 spherical plain bearing 17 bevel 18 second substrate mount 19 stack 20 film frame combination 21 film 22 rack 22d cover 23 film frame 24, 24′ ends 25 spacer 26 peripheral section 27 base 27b bottom 28 holding means 29 holding means A distance B ring width D.sub.i inner diameter D.sub.a outer diameter D.sub.k diameter H ring height M distance L detachment direction l inner angle d thickness F.sub.1, F.sub.2, F.sub.n driving forces (tensile force) G opposing force K.sub.1, K.sub.2, K.sub.n detachment moments W, W′ bending angle