METHOD FOR THE LOW-LOSS PRODUCTION OF MULTI-COMPONENT WAFERS

Abstract

The present invention relates to a method for producing a multi-component wafer, in particular a MEMS wafer. The method according to the invention comprises at least the following steps: providing a bonding wafer (2), wherein at least one surface portion (4) of the bonding wafer (2) is formed by an oxide film, providing a dispenser wafer (6), wherein the dispenser wafer (6) is thicker than the bonding wafer (2), bringing the dispenser wafer (6) into contact with the surface portion (4) of the bonding wafer (2) that is formed by the oxide film, forming a multilayer arrangement (8) by connecting the dispenser wafer (6) and the bonding wafer (2) in the region of the contact, producing modifications (18) in the interior of the dispenser wafer (6) for predefining a detachment region (11) for separating the multilayer arrangement (8) into a detaching part (14) and a connecting part (16), wherein the production of the modifications (18) takes place before the formation of the multilayer arrangement (8) or after the formation of the multilayer arrangement (8), separating the multilayer arrangement along the detachment region as a result of a weakening of the multilayer arrangement brought about by the production of a sufficient number of modifications or as a result of production of mechanical stresses in the multilayer arrangement, wherein the connecting part (16) remains on the bonding wafer (2) and wherein the split-off detachment part (14) has a greater thickness than the connecting part (16).

Claims

1. A method for producing a multi-component wafer (1), in particular a MEMS wafer, at least comprising the following steps: providing a bonding wafer (2), wherein at least one surface portion (4) of the bonding wafer (2) is formed by an oxide layer, providing a donor wafer (6), wherein the donor wafer (6) is thicker than the bonding wafer (2), bringing the donor wafer (6) into contact with the surface portion (4) of the bonding wafer (2) formed by the oxide layer, forming a multilayer arrangement (8) by connecting the donor wafer (6) and the bonding wafer (2) in the region of the contact, producing modifications (18) in the interior of the donor wafer (6) for predefining a detachment region (11) for separating the multilayer arrangement (8) into a separation part (14) and a connection part (16) by means of at least one LASER beam, wherein the modifications (18) are produced prior to the formation of the multilayer arrangement (8) or after the formation of the multilayer arrangement (8), separating the multilayer arrangement along the detachment region as a result of a weakening of the multilayer arrangement brought about by the production of a sufficient number of modifications or as a result of production of mechanical stresses in the multilayer arrangement, wherein the connection part (16) remains on the bonding wafer (2), and wherein the split-off separation part (14) has a greater thickness than the connection part (16).

2. The method according to claim 1, further comprising the following steps: cleaning the separation part (14) and/or converting the separation part (14) into a further bonding wafer (3) by a treatment of at least one surface portion of the separation part (14), and providing the further bonding wafer (3) so as to be brought into contact with a further donor wafer.

3. The method according to claim 2, characterised in that the treatment comprises an oxidation process, in particular an SiOx process, whereby an oxidation of the at least one surface portion is effected.

4. The method according to any one of the preceding claims, characterised in that the donor wafer (6) has a first thickness D1, the bonding wafer (2) has a second thickness D2, the separation part (14) has a third thickness D3, and the connection part (16) has a fourth thickness D4, wherein the thickness D1 is greater than the sum of the thicknesses D3 and D4, wherein the sum of the thicknesses D3 and D4 is greater than the thickness D3, wherein the thickness D3 is greater than the thickness D2 by a thickness DL.

5. The method according to claim 4, characterised in that the thickness DL is less than 200 m, in particular less than 100 m, and is removed as a result of polishing and/or etching steps.

6. The method according to any one of the preceding claims, characterised in that the LASER beams (20) are emitted from a LASER device (22), wherein the LASER device (22) is preferably a picosecond LASER or a femtosecond LASER or wherein the modifications (18) are local cracks in the crystal lattice and/or material portions in the interior of the donor wafer (6) converted into another phase.

7. The method according to claim 6, characterised in that the energy of the LASER beams (20) of the fs LASER is selected in such a way that the propagation of damage of each modification (18) in the donor substrate is less than 3 times the Rayleigh length, preferably less than the Rayleigh length, and particularly preferably less than a third of the Rayleigh length and/or the wavelength of the LASER beams (20) of the fs LASER is selected in such a way that the absorption of the donor substrate (6) is less than 10 cm.sup.1 and preferably less than 1 cm.sup.1 and particularly preferably less than 0.1 cm.sup.1 and/or the individual modifications (18) in each case are produced as a result of a multi-photon excitation brought about by the fs LASER.

8. The method according to claim 6 or 7, characterised in that the LASER beams (20) for producing the modifications (18) infiltrate the donor wafer (6) over a surface which is part of the connection part (16).

9. The method according to any one of the preceding claims, further comprising the following step: removing material of the multilayer arrangement starting from a surface (14) extending in the peripheral direction of the multilayer arrangement towards the centre (Z) of the multilayer arrangement, in particular so as to produce a peripheral indentation (16), wherein the detachment region is exposed by the material removal, separating the solid-body layer from the multilayer arrangement, wherein the multilayer arrangement is weakened in the detachment region by the modifications in such a way that the solid-body layer (11) detaches from the multilayer arrangement as a result of the material removal or after the material removal, such a number of modifications are produced that the donor substrate is weakened in the detachment region in such a way that the solid-body layer (11) detaches from the donor substrate (12) or a stress-producing layer (114) is produced or arranged on a surface (116) of the donor substrate (12), which surface is oriented at an incline relative to the peripheral surface and in particular is planar, and mechanical stresses are produced in the donor substrate (12) by a thermal treatment of the stress-producing layer (114), wherein a crack (120) for detachment of a solid-body layer (11) is produced as a result of the mechanical stresses and propagates, starting from the surface of the donor substrate exposed by the material removal, along the modifications (110).

10. The method according to claim 9, characterised in that the detachment region predefined by the modifications (110) is distanced further from the peripheral surface of the donor substrate (12) prior to the material removal than after the material removal and/or the modifications (110) for predefining the detachment region are produced prior to the material removal, and by means of the material removal a reduction of the distance of the detachment region to less than 10 mm, in particular to less than 5 mm and preferably to less than 1 mm, is achieved at least at specific points, or the modifications for predefining the detachment region are produced after the material removal, wherein the modifications (110) are produced in such a way that the detachment region is distanced, at least at specific points, by less than 10 mm, in particular less than 5 mm, and preferably less than 1 mm, from a surface exposed by the material removal and/or the material is removed by means of ablation beams (8), in particular ablation LASER beams, or ablation fluids or an indentation (6) with an asymmetrical design is produced by the material removal or the material removal is performed at least in portions in the peripheral direction of the donor substrate (12) as a reduction of the radial extent of the donor substrate (12), in the entire region between the detachment region and a surface of the donor substrate (12) distanced homogeneously from the detachment region, and/or the indentation (16) surrounds the donor substrate (12) completely in the peripheral direction and/or the indentation (16) runs towards the centre (Z) as far as an indentation end (118) in a manner becoming increasingly narrower, in particular in a wedge-like manner, wherein the indentation end (118) lies in the plane in which the crack (120) propagates and/or the asymmetric indentation (16) is produced by means of a grinding tool (122) that is negatively shaped at least in part in order to make the indentation (16) and/or the grinding tool (122) has at least two differently shaped processing portions (124, 126), wherein a first processing portion (124) is intended for processing of the donor substrate (12) in the region of the underside (128) of a solid-body slice (11) to be separated and a second processing portion (126) is intended for processing the donor substrate (12) in the region of the upper side (130) of the solid-body slice (11) to be separated from the donor substrate (12) and/or the first processing portion (124) produces a deeper or larger-volume indentation (16) in the donor substrate (12) than the second processing portion (126), wherein the first processing portion (124) and/or the second processing portion (126) have/has curved or straight grinding faces (132, 134) and/or the first processing portion (124) has a curved main grinding face (132) and the second processing portion (126) has a curved secondary grinding face (134), wherein the radius of the main grinding face (132) is greater than the radius of the secondary grinding face (134), the radius of the main grinding face (132) is preferably at least twice as large as the radius of the secondary grinding face (134) or the first processing portion (124) has a straight main grinding face (132) and the second processing portion (126) has a straight secondary grinding face (134), wherein, by means of the main grinding face (132), more material is removed from the donor substrate (12) than with the secondary grinding face (134) or the first processing portion (124) has a straight main grinding face (132) and the second processing portion (126) has a curved secondary grinding face (134) or the first processing portion (124) has a curved main grinding face (132) and the second processing portion (126) has a straight secondary grinding face (134) and/or the ablation LASER beams (18) are produced with a wavelength in the range between 300 nm and 10 m, with a pulse length of less than 100 microseconds and preferably less than 1 microsecond, and particularly preferably less than 1/10 of a microsecond, and with a pulse energy of more than 1 J and preferably more than 10 J and/or the material to be removed in the entire region between the detachment region and the surface distanced homogeneously from the detachment region describes an annular, in particular cylindrical design and/or wherein the LASER beams (112) are emitted from a LASER device (146), wherein the LASER device (146) is a picosecond LASER or a femtosecond LASER and/or the energy of the LASER beams (112), in particular of the fs LASER, is selected in such a way that the propagation of damage of each modification (110) in the donor substrate (12) is less than 3 times the Rayleigh length, preferably less than the Rayleigh length, and particularly preferably less than a third of the Rayleigh length and/or the wavelength of the LASER beams (112), in particular of the fs LASER, is selected in such a way that the absorption of the donor substrate (12) is less than 10 cm.sup.1 and preferably less than 1 cm.sup.1 and particularly preferably less than 0.1 cm.sup.1 and/or the individual modifications (110) are produced in each case as a result of a multi-photon excitation brought about by the LASER beams (112), in particular the fs LASER, and/or the LASER beams (112) for producing the modifications (110) penetrate the donor wafer (12) over a surface (116) which is part of the solid-body slice (11) to be separated and/or the stress-producing layer (114) comprises or consists of a polymer, in particular polydimethylsiloxane (PDMS), wherein the thermal treatment is performed in such a way that the polymer experiences a glass transition, wherein the stress-producing layer (114) is temperature-controlled, in particular by means of liquid nitrogen, to a temperature below room temperature or below 0 C. or below 50 C. or below 100 C. or below 110 C., in particular to a temperature below the glass transition temperature of the stress-producing layer (114) and/or the ablation radiation comprises accelerated ions and/or plasma and/or LASER beams and/or is formed by electron beam heating or ultrasound waves and/or is part of a lithographic method (electron beam, UV, ions, plasma) with at least one etching step following a previously executed photoresist coating and/or the ablation fluid is a liquid jet, in particular a water jet of a water jet cutting process.

11. The method according to any one of the preceding claims, characterised in that the LASER beam (212) or the LASER beams is/are inclined relative to the planar surface (216) of the donor substrate (22) in such a way that it/they penetrates/penetrate the donor substrate at an angle that is unequal to 0 C. or 180 C. relative to the longitudinal axis of the donor substrate, wherein the LASER beam (212) is focused in the donor substrate (22) for production of the modification (210), wherein preferably a first portion (236) of the LASER beam (212) penetrates the donor substrate (22) at a first angle (238) to the planar surface (216) of the donor substrate (22) and at least one further portion (240) of the LASER beam (212) penetrates the donor substrate (22) at a second angle (242) to the planar surface (216) of the donor substrate (22), wherein the value of the first angle (238) differs from the value of the second angle (242), wherein the first portion (236) of the LASER beam (212) and the further portion (240) of the LASER beam (212) are focused in the donor substrate (22) for production of the modification (210).

12. The method according to claim 11, characterised in that the totality of the LASER beams (212) for producing modifications (210) in the region of the centre (Z) of the donor substrate (22) and for producing modifications (210) in the region of an edge (244) provided in the radial direction, in particular at a distance of less than 10 mm and preferably of less than 5 mm and particularly preferably of less than 1 mm from the edge of the donor substrate (22), is oriented in the same orientation relative to the planar surface (216) of the donor substrate (22) and/or the first portion (236) of the LASER beams (212) penetrates the donor substrate (22) at a first angle (238) to the planar surface (216) of the donor substrate (22) and the further portion (240) of the LASER beams (212) penetrates at a second angle (242) for production of modifications (210) in the region of the centre (Z) of the donor substrate (22) and for production of modifications (210) in the region of an edge (244) of the donor substrate (22) provided in the radial direction, wherein the value of the first angle (238) is always different from the value of the second angle (242) and/or wherein the LASER beams (212) are emitted from a LASER device (246), wherein the LASER device (246) is a picosecond LASER or a femtosecond LASER and/or the energy of the LASER beams (212), in particular of the fs LASER, is selected in such a way that the propagation of damage of each modification (210) in the donor substrate (22) is less than 3 times the Rayleigh length, preferably less than the Rayleigh length, and particularly preferably less than a third of the Rayleigh length and/or the wavelength of the LASER beams (212), in particular the fs LASER, is selected in such a way that the absorption of the donor substrate (22) is less than 10 cm.sup.1 and preferably less than 1 cm.sup.1 and particularly preferably less than 0.1 cm.sup.1 and/or the individual modifications (210) are produced in each case as the result of a multi-photon excitation brought about by the LASER beams (212), in particular of the fs LASER and/or the LASER beams (212) for producing the modifications (210) penetrate the donor wafer (22) over a surface (216) which is part of the solid-body slice (21) to be detached and/or the LASER beam (212) penetrates the donor substrate (22) over a peripheral surface of the donor substrate (22), in particular in the radial direction of the donor substrate (22), and/or the LASER beams (212) introduced into the donor substrate (22) over the peripheral surface produce modifications (210) which are elongate, in particular filament-like, and/or the LASER beams (212) introduced at a position of the peripheral surface of the donor substrate (22) are focussed at different penetration depths for production of a plurality of modifications (210), wherein the modifications (210) are produced here preferably starting from the deepest depth to the shallowest depth and/or a means for aberration adjustment is provided, and by the means an aberration adjustment of the LASER beams penetrating over the peripheral surface is made.

13. The method according to any one of the preceding claims further comprising the following steps: arranging or producing a stress-producing layer (210) on at least one exposed surface (212) of the multilayer arrangement (28), thermally treating the stress-producing layer (210) in order to produce the mechanical stresses within the multilayer arrangement (28), wherein the stresses in the portion of the multilayer arrangement (28) formed by the donor wafer (26) are so great that a crack is formed in the donor wafer (26) along the detachment region (211), by means of which crack the donor wafer (26) is split into the separation part (214) and the connection part (216), wherein the stress-producing layer (210) comprises or consists of a polymer, in particular polydimethylsiloxane (PDMS), wherein the thermal treatment is performed in such a way that the polymer experiences a glass transition, wherein the stress-producing layer (210) is temperature-controlled, in particular by means of liquid nitrogen, to a temperature below room temperature or below 0 C. or below 50 C. or below 100 C. or below 110 C., in particular to a temperature below the glass transition temperature of the stress-producing layer (210).

14. Use of a substrate as donor wafer (6) and bonding wafer (2) in a multi-component wafer production method, in particular a MEMS wafer production method, wherein the substrate is arranged as donor wafer (6) on a further bonding wafer (3), which has an oxidation layer, wherein the donor wafer (6) is divided, being split into a connection part (16) and a separation part (14), as a result of propagation of a crack, and wherein the separation part (14) serves as bonding wafer (2) after treatment in a SiOx process, wherein the bonding wafer (2) is connected to a further donor substrate in order to form a multilayer arrangement (8).

15. A multi-component wafer (1), in particular a MEMS wafer, at least comprising a bonding wafer (2), wherein at least one surface portion of the bonding wafer (2) is formed by an oxide layer, a connection part (16) split off from a donor wafer (6) as the result of propagation of a crack, wherein the connection part (16) is arranged in an integrally bonded manner on a surface portion formed by the oxide layer, and wherein the bonding wafer (2) is a portion, prepared by means of an oxidation treatment, in particular an SiOx treatment, of a separation part (14) separated from a donor wafer.

Description

[0058] In the drawings:

[0059] FIG. 1 shows a multi-component wafer production process;

[0060] FIG. 2 shows an alternative sub-process of the multi-component wafer production process according to the invention;

[0061] FIG. 3 shows a further or supplemented multi-component wafer production process;

[0062] FIG. 4 shows a first example of an edge treatment within the scope of the invention;

[0063] FIG. 5 shows examples of contours of grinding tools as can be used in accordance with the method shown in FIG. 4;

[0064] FIG. 6 shows a second example of an edge treatment within the scope of the invention; and

[0065] FIGS. 7a-7d show a third example of an edge treatment within the scope of the invention; and

[0066] FIGS. 8a-8b show an illustration of a problem occurring when producing modifications by means of LASER beams in the edge region of a donor substrate or multilayer arrangement;

[0067] FIG. 9 shows an example of an edge treatment within the scope of the solid-body slice production or solid-body layer production according to the invention;

[0068] FIG. 10 shows a further example of an edge treatment within the scope of the solid-body slice production or solid-body layer production according to the invention;

[0069] FIG. 11 shows an illustration that shows problems that occur with the production of modifications in a solid body if the modifications are produced by means of LASER beams;

[0070] FIG. 12 shows an illustration that shows the different LASER beam angles;

[0071] FIGS. 13a/13b show an illustration of a modification production step and a schematic illustration of the produced modifications;

[0072] FIGS. 14a/14b show two illustrations of modification production steps; and

[0073] FIG. 15 shows production of a modification with an aberration adjustment.

[0074] FIG. 1 shows a number of steps of a method according to the invention for producing a multi-component wafer 1, in particular a MEMS wafer.

[0075] In accordance with this illustration, a bonding wafer 2 is first provided in a first step I., wherein at least one surface portion 4 of the bonding wafer 2 is formed by an oxide layer. A donor wafer 6 is also provided in the first step I., wherein the donor wafer 6 is thicker than the bonding wafer.

[0076] In a second step II., the donor wafer 6 is brought into contact with the surface portion 4 of the bonding wafer 2 formed by the oxide layer. This leads to the formation of a multilayer arrangement 8 by connection of the donor wafer 6 and of the bonding wafer 2 in the region of the contact.

[0077] In a third step III., modifications 18 are produced in the interior of the donor wafer 6 for predefining a detachment region 11 for separation of the multilayer arrangement 8 into a separation part 14 and a connection part 16, wherein the modifications 18 are produced before the formation of the multilayer arrangement 8 or after the formation of the multilayer arrangement 8.

[0078] Step IV. shows the step of separation of the multilayer arrangement 8 along the detachment region 11 as a result of a weakening of the multilayer arrangement brought about by the production of a sufficient number of modifications, wherein the connection part 16 remains on the bonding wafer 2, and wherein the split-off separation part 14 has a greater thickness than the connection part 16.

[0079] The separation part 14 is then supplied in a further step to a treatment device 24. The treatment device 24 produces an oxide layer by material application and/or by material conversion, by means of which oxide layer at least one, preferably planar, surface of the separation part 14 is formed.

[0080] Before or after production of the oxide layer, a material-removing step is preferably performed, in particular a polishing, lapping, etching and/or chemical-mechanical polishing, by means of which at least one surface or a surface portion of the detachment layer 14 or of the bonding wafer 2 is smoothed, i.e. experiences a roughness reduction at least in part.

[0081] By means of the roughness reduction and the oxide layer production, in particular an SiOx process, the separation part 14 is reconfigured into a further bonding wafer 3. This further bonding wafer 3 is then used as bonding wafer 2 in accordance with the method described by steps I-IV.

[0082] FIG. 2 shows an alternative production of the modifications 18. In accordance with this variant the modifications 18 are produced before the production of a multilayer arrangement 8. This embodiment is advantageous since the LASER beams 20 can penetrate the donor wafer 6 over a surface of the donor wafer 6 which is part of the connection part 16 once the donor wafer 6 has been divided.

[0083] FIG. 3 shows a further or further supplemented multi-component wafer production process according to the invention, in particular a MEMS wafer production process. In accordance with this multi-component wafer production process, a bonding wafer 2 and a donor wafer 6 are provided in a first step I. The bonding wafer 2 has an oxide layer on preferably at least one surface, in particular on at least one planar surface 4. Here, the oxide layer can be produced by conversion of the starting material of the bonding wafer 2 or by deposition or coating. The donor wafer 6 preferably does not have an oxide layer.

[0084] In step II., the bonding wafer 2 and the donor wafer 6 are connected to one another, in particular integrally bonded to one another. The oxide layer or at least part of the oxide layer of the bonding wafer 2 is hereby directly superimposed or covered by the donor wafer 6. The surface of the oxide layer and the surface of the donor wafer 6, which are connected to one another here, both particularly preferably have a surface finish provided by polishing, lapping, etching and/or chemical-mechanical polishing. The mean roughness Ra is preferably less than 76 m, or less than 38 m or less than 12.5 m or less than 6 m or less than 3 m or less than 2.5 m or less than 1.25 m or less than 0.5 m.

[0085] In step III., the multilayer arrangement 8, in particular the donor substrate 6, is acted on by LASER beams 20 of a LASER device 22. The LASER beams 20 cause modifications 18 of the material forming the donor wafer 6 to be created or produced in the interior of the donor wafer 6, in particular on account of a multi-photon excitation. A multiplicity of modifications 18 are preferably produced, wherein the individual modifications 18 preferably lie in the same plane. The totality of modifications 18 thus constitutes a precise producible weakening of the donor wafer at 6, which predefines the course of formation of a crack for separating the donor wafer 6 into two parts in the sense of a perforation. The LASER beams 20, in accordance with the shown example, penetrate the donor wafer 6 over a surface of the donor wafer 6 which is part of the thicker part following the splitting of the donor wafer 6 into two parts.

[0086] An alternative production of modifications 18 is shown by FIG. 2.

[0087] In step IV., a stress-producing layer 10 is arranged or produced on a preferably further exposed and particularly preferably planar surface of the bonding wafer 2 and/or on a preferably further exposed and particularly preferably planar surface of the donor wafer 6. The stress-producing layer 10 is here preferably a polymer layer, in particular a layer consisting of PDMS or comprising PDMS.

[0088] In step V., the stress-producing layer 10 arranged on the bonding wafer 2 and/or the stress-producing layer 10 arranged on the donor wafer 6 are/is exposed to a thermal treatment, whereby the stress-producing layer 10 contracts and thus introduces mechanical stresses into the multilayer arrangement 8 in such a way that a crack forms and propagates in the region of the modifications 18. The thermal treatment is preferably provided via a cooling device 26, which particularly preferably dispenses a free-flowing substance 28, which cools the stress-producing layer 10. The free-flowing substance 28 is here preferably a fluid and particularly preferably liquid nitrogen. By means of the crack, the donor wafer 6 is split into two parts: a connection part 16 and a separation part 14, wherein the connection part 16 remains on the bonding wafer 2 on account of the integrally bonded connection to the bonding wafer 2, and the separation part 14 is separated. The separation part 14 and the connection part 16 both have a wafer-like design. The separation part 14 is preferably thicker than the connection part 16, the separation part 14 is preferably at least 1.25 times or at least 1.5 times or at least 1.75 times or at least 2 times or at least 2.25 times or at least 2.5 times or at least 2.75 times or at least 3 times or at least 3.25 times or at least 3.5 times or at least 3.75 times or at least 4 times or at least 4.25 times or at least 4.5 times or at least 4.75 times or at least 5 times or at least 5.25 times or at least 5.5 times or at least 5.75 times or at least 6 times or at least 6.25 times as thick as the connection part 16. The thickness of the connection part 16 is preferably determined by the mean distance of the planar surfaces of the connection part 16 from one another. The thickness of the separation part 14 is preferably determined by the mean distance of the planar surfaces of the separation part 14 from one another.

[0089] In step VI, the stress-producing layers 10 are removed from the produced multi-component wafer 1, in particular MEMS wafer 1, by cleaning and are preferably likewise removed from the separation part 14.

[0090] The separation part 14 is then fed in a further step to a treatment device 24. The treatment device 24 produces an oxide layer by material application and/or by material conversion, by means of which oxide layer at least one preferably planar surface of the separation part 14 is formed.

[0091] Before or after production of the oxide layer, a material-removing step is preferably performed, in particular a polishing, lapping, etching and/or chemical-mechanical polishing, by means of which at least one surface or a surface portion of the detachment layer 14 and/or of the bonding wafer 2 is smoothed, i.e. experiences a roughness reduction at least in part.

[0092] Due to the roughness reduction and the oxide layer production, the separation part 14 is reconfigured to form a further bonding wafer 3. This further bonding wafer 3 is then used as bonding wafer 2 in accordance with the method described by steps I-VI.

[0093] The present invention thus relates to a method for producing a multi-component wafer 1, in particular a MEMS wafer 1. The method according to the invention preferably comprises at least the following steps: providing a bonding wafer 2, wherein at least one surface portion 4 of the bonding wafer 2 is formed by an oxide layer, providing a donor wafer 6, wherein the donor wafer 6 is thicker than the bonding wafer 2, bringing the donor wafer 6 into contact with the surface portion 4 of the bonding wafer 2 formed by the oxide layer, forming a multilayer arrangement 8 by connecting the donor wafer 6 and the bonding wafer 2 in the region of the contact, arranging or producing a stress-producing layer 10 on at least one exposed planar surface 12 of the multilayer arrangement 8, thermally treating the stress-producing layer in order to produce mechanical stresses within the multilayer arrangement 8, wherein the stresses in the portion of the multilayer arrangement 8 formed by the donor wafer 6 are so great that a crack forms in the donor wafer 6, by means of which crack the donor wafer 6 is split into a separation part 14 and a connection part 16, wherein the connection part 16 remains on the bonding wafer 2, and wherein the split-off separation part 14 has a greater thickness than the connection part 16.

[0094] The present invention thus relates to a method for producing a multi-component wafer, in particular a MEMS wafer. The method according to the invention comprises at least the following steps: providing a bonding wafer 2, wherein at least one surface portion 4 of the bonding wafer 2 is formed by an oxide layer, providing a donor wafer 6, wherein the donor wafer 6 is thicker than the bonding wafer 2, bringing the donor wafer 6 into contact with the surface portion 4 of the bonding wafer 2 formed by the oxide layer, forming a multilayer arrangement 8 by connecting the donor wafer 6 and the bonding wafer 2 in the region of the contact, producing modifications 18 in the interior of the donor wafer 6 for predefining a detachment region 11 for separating the multilayer arrangement 8 into a separation part 14 and a connection part 16, wherein the modifications 18 are produced prior to the formation of the multilayer arrangement 8 or after the formation of the multilayer arrangement 8, separating the multilayer arrangement along the detachment region as a result of a weakness of the multilayer arrangement brought about by the production of a sufficient number of modifications or as a result of a production of mechanical stresses in the multilayer arrangement, wherein the connection part 16 remains on the bonding wafer 2, and wherein the split-off separation part 14 has a thickness greater than the connection part 16.

[0095] FIG. 4 shows 5 illustrations, by means of which examples of the solid-body slice production or wafer production according to the invention are shown. Illustration 1 shows a grinding tool 122, which has two processing portions 24 distanced from one another, which each form a main grinding face 132. The main grinding faces 132 are formed here so that they produce indentations 16 in a donor substrate 12. The grinding tool 122 is preferably formed as a rotary grinding tool or as a belt grinding tool.

[0096] Illustration 2 of FIG. 4 shows a donor substrate 12, in which indentations 16 have been produced by means of the grinding tool 122. Here, the indentations 16 are distanced preferably uniformly from one another in the longitudinal direction of the donor wafer 12, wherein it is also conceivable for the distances to be of different sizes. In accordance with the second illustration in FIG. 5, modifications 110 are also produced in the donor substrate 12 by means of a LASER device 146. The LASER device 146 for this purpose emits LASER beams 112, which penetrate the donor substrate 12 over a preferably planar surface 116 of the donor substrate 12, and a modification 110 of the lattice structure of the solid body or of the donor substrate 12 is produced or brought about at a focus point 148, in particular by a multi-photon excitation. Here, the modification 110 is preferably a material conversion, in particular a conversion of the material into another phase, or a material degradation.

[0097] The third illustration shows that a stress-producing layer 114 has been produced or arranged on the surface 116 over which the LASER beams 112 were introduced into the donor substrate 12 for production of the modifications 110. The stress-producing layer 114 is thermally treated or temperature-controlled, in particular cooled, in order to produce mechanical stresses in the donor substrate 12. By means of the thermal treatment of the stress-producing layer 114, the stress-producing layer 114 contracts, whereby the mechanical stresses are produced in the donor substrate 12. The previously produced indentations 16 form notches, through which the mechanical stresses can be conducted in such a way that the crack 120 resulting from the stresses propagates in a targeted manner in the region of crack formation predefined by the modifications 110. The indentation ends 118 therefore are preferably adjacent to the particular region of crack formation predefined by the modifications 110. It is preferably always the case that only precisely the solid-body layer 11 of which the indentation 16 is distanced least far from the stress-producing layer 114 is split off.

[0098] Illustration 4 shows a state following crack propagation. The solid-body slice 11 has been split off from the donor substrate 12, and the stress-producing layer 114 initially still remains on the surface 116 of the solid-body slice 11.

[0099] Reference sign 128 denotes the side of the solid-body slice 11 which is denoted here as the underside of the solid-body slice 11, and reference sign 130 denotes the side of the solid-body slice 11 which is denoted here as the upper side of the solid-body slice 11.

[0100] Illustration 5 shows a method in which the solid-body layer 11 is detached from the donor substrate 12 without a stress-producing layer 114. Here, following production of the indentation 16, so many modifications 110 are preferably produced by means of LASER beams 112, that the solid-body layer 11 detaches from the donor substrate 12. The dashed line Z here preferably characterises a centre or an axis of rotation of the donor substrate 12. The donor substrate 12 is preferably rotatable about the axis of rotation Z.

[0101] FIG. 5 shows two illustrations, wherein each illustration shows a grinding tool 122 with a specific contour. If reference is made to a planar, straight or curved portion with regard to the grinding tool, this is always understood to mean a portion of the shown contour. Of course, the grinding tool 122 can be formed for example as a rotary grinding tool, whereby the portions adjacent to the contour in the peripheral direction would preferably extend in a curved manner in the peripheral direction. The grinding tool 122 shown in the first illustration of FIG. 5 has a first processing portion 124, which has a curved main grinding face 132, and has a second processing portion 126, which has a curved secondary grinding face 134, wherein the radius of the main grinding face 132 is greater than the radius of the secondary grinding face 134, preferably the radius of the main grinding face 132 is at least twice, three times, four times or five times as great as the radius of the secondary grinding face 134.

[0102] In accordance with the second illustration of FIG. 5, the first processing portion 124 of the grinding tool 122 has a straight main grinding face 132 and the second processing portion 126 has a straight secondary grinding face 134, wherein more material is removed from the donor substrate 12 by means of the main grinding face 132 than by means of the secondary grinding face 134.

[0103] The grinding tools 122 shown in FIG. 5 and the indentations produced by the shown grinding tools 122 can likewise be used in respect of the illustrations shown in FIG. 4.

[0104] FIG. 6 shows a further variant of the method according to the invention. By means of a comparison of the first and fifth illustration, it can be seen that the modifications 110 produced by means of the LASER beams 112, in the case of a planar surface 116, can be produced closer to the edge 144 than if the tip of the edge 117 of the surface 116 is removed, as shown in the fifth illustration. The LASER beams 112 here penetrate the donor substrate 12, similarly to the modification production explained with reference to FIG. 4.

[0105] The second illustration of FIG. 6 shows the production of an indentation 16 starting from a peripheral surface 14 in the direction of the centre Z of the donor substrate 12, wherein the indentation is produced by means of ablation LASER beams 18 of an ablation LASER (not shown). The ablation LASER beams here preferably evaporate the material of the donor substrate 12 in order to produce the indentation 16.

[0106] Illustration 3 of FIG. 6 corresponds substantially to illustration 3 of FIG. 5, wherein merely the form of the indentation here is not asymmetrical, but instead is symmetrical. In accordance with this illustration as well, a stress-producing layer 114 is thus produced or arranged on the donor substrate 12 and is thermally treated, in particular by means of liquid nitrogen, in order to produce mechanical stresses for initiating a crack 120.

[0107] Illustration 4 of FIG. 6 shows the solid-body slice 11 split off from the donor substrate 12, with the stress-producing layer still arranged on said solid-body slice.

[0108] It can also be seen from illustration 5 of FIG. 6 that in the case of a donor substrate 12 of which the tip of the edge 117 is processed, the indentation 16 to be produced by means of ablation LASER beams 18 must reach further in the direction of the centre of the donor substrate 12 than if the tip of the edge 117 is not processed. Here, however, it is also conceivable that the indentation is not produced by means of ablation LASER beams 18, but instead by means of a grinding tool 122 (as is known for example from FIGS. 4 and 5).

[0109] FIG. 7a shows an additional or alternative solution according to the invention for the separation of solid-body layers 11 from a donor substrate 12. In accordance with FIG. 7a, a detachment region 111 is produced in the interior of the donor substrate 2. The modifications 110 are preferably distanced here from a peripheral delimiting face 150 of the donor substrate 12. The modifications 110 are preferably produced similarly to illustration 2 of FIG. 4. Here, it is conceivable that the LASER beams 112 are introduced into the donor substrate 12 from below or from above, i.e. over the surface 116.

[0110] FIG. 7b schematically shows the processing of the donor substrate 12 by means of an ablation tool 122, in particular a tool for machining the donor substrate 12, such as a grinding tool 122. By means of the processing, material is removed, at least in portions in the peripheral direction of the donor substrate 12, in the entire region between the detachment region and a surface of the donor substrate 12 distanced preferably homogeneously, in particular in parallel, from the detachment region, for reduction of the radial extent of the donor substrate 12. The material is preferably removed in an annular manner, in particular with a constant or substantially constant radial extent.

[0111] FIG. 7c shows an example of a state after the removal of the material. Here, it is conceivable for example that the material is removed in the axial direction of the donor substrate 12 up to the detachment plane, or therebeneath or thereabove.

[0112] FIG. 7d shows a state following the separation or detachment of the solid-body layer 11 from the donor substrate 12.

[0113] FIGS. 8a and 8b show a problem in the edge region of the donor substrate 12 occurring with the production of modifications by means of LASER beams 112. By means of the different refractive indices in the air and in the donor substrate, the LASER beam portions 138, 140 of a LASER beam 112 do not coincide exactly with one another, thus resulting in undesirable effects, such as the production of defects at undesirable locations, an undesirable local heating, or a prevention of the production of a modification.

[0114] FIG. 8b shows that a problem-free production of modifications 110 can be provided only if the modification 110 to be produced is distanced from the peripheral surface of the donor substrate 12 to such an extent that both LASER beam portions 138, 140 are each refracted through material with the same refractive index and preferably over the same distance. However, this means that the production of the modification, as it occurs in the region distanced from the edge region, cannot be readily extended to the edge region.

[0115] The present invention thus relates to a method for separating solid-body slices 11 from a donor substrate 12. Here, the method according to the invention comprises the following steps:

[0116] Providing a donor substrate 12, removing material of the donor substrate 12 starting from a surface 14 extending in the peripheral direction of the donor substrate 2 towards the centre Z of the donor substrate 12 in order to produce an indentation 16, wherein the material is removed by means of ablation LASER beams 18 and/or the indentation 16 is produced asymmetrically, producing modifications 110 in the interior of the donor substrate 12 by means of further LASER beams 112, wherein the modifications 10 are positioned in such a way that they are adjacent to the indentation 16, wherein the solid-body slice 11 is detached from the donor substrate 12 by means of the produced modifications 110, or a stress-producing layer 114 is produced or arranged on a surface 116 of the donor substrate 12, which surface is oriented at an incline to the peripheral surface and in particular is planar, and mechanical stresses are produced in the donor substrate 12 by means of a thermal treatment of the stress-producing layer 114, wherein a crack 120 for separating a solid-body layer 11 is created by the mechanical stresses and propagates, starting from the indentation 16, along the modifications 110.

[0117] The present invention thus relates to a method for separating solid-body slices 11 from a donor substrate 12. Here, the method according to the invention comprises the following steps:

[0118] producing modifications 110 in the interior of the donor substrate 12 by means of LASER beams 112, wherein a detachment region is predefined by the modifications 110, along which detachment region the solid-body layer 11 is separated from the donor substrate 12 or the multilayer arrangement,

[0119] removing material of the donor substrate 12, starting from a surface 14 extending in the peripheral direction of the donor substrate 12 towards the centre Z of the donor substrate 12, in particular in order to produce a peripheral indentation 16, wherein the detachment region is exposed by the material removal, separating the solid-body layer from the donor substrate, wherein the donor substrate is weakened in the detachment region by the modifications in such a way that the solid-body layer 11 is detached from the donor substrate 12 as a result of the material removal or such a number of modifications are produced after the material removal that the donor substrate is weakened in the detachment region in such a way that the solid-body layer 11 is detached from the donor substrate 12 or a stress-producing layer 114 is produced or arranged on a surface 16 of the donor substrate 12, which surface is oriented at an incline to the peripheral surface and in particular is planar, and mechanical stresses are produced in the donor substrate 12 by means of a thermal treatment of the stress-producing layer 114, wherein by means of the mechanical stresses a crack 120 for separating a solid-body layer 11 is created and propagates, starting from the surface of the donor substrate exposed by the material removal, along the modifications 110.

[0120] FIG. 9 shows 4 illustrations. In the first illustration of FIG. 9, a donor substrate 22 is shown, which is acted on by LASER beams 212. The LASER beams 212 are inclined in their totality relative to the surface 216 over which the LASER beams penetrate the donor substrate 22, in such a way that the inclination deviates from an angle of 90. A first portion 236 of LASER beams 212 is preferably oriented at a first angle 238 relative to the surface 216, and a further portion 240 of LASER beams 212 is oriented at a second angle 242 relative to the surface 216. The LASER beam portions 236 and 240, for production of all modifications 212 produced for separation of a specific solid-body layer 21, are preferably always inclined identically relative to the surface 216 over which the LASER beam portions 236, 240 penetrate the donor substrate 22. It can also be inferred from the first illustration of FIG. 12 that the focus point 248 can be guided in the donor substrate 22 as far as the edge 244 or directly adjacently to the edge 244 for production of modifications 210 on account of the inclined LASER beam portions 236, 240.

[0121] It can also be deduced from illustration 2 of FIG. 9 that, in accordance with the LASER beam portions 236, 240 oriented at an incline, a material-removing treatment of the edge 244 of the donor substrate 22 is not necessary or is only necessary to a significantly reduced extent. The stress-producing layer 214 arranged or produced on the surface 216 causes a production of mechanical stresses in the donor substrate 22, whereby a crack 220 propagates in a very precisely guided manner from the edge 244 into the donor substrate 22 on account of the modifications 210 produced as far as the edge 244.

[0122] Illustration 3 of FIG. 9 shows a solid-body slice 21 completely split off from the donor substrate 22, wherein the solid-body slice 21 preferably has not experienced any edge tip treatment in accordance with this embodiment.

[0123] Illustration 4 of FIG. 9 indicates that a solid-body slice 21 can be removed from the donor substrate 22 likewise by production of modifications 210 by means of LASER beams 236, 240 (without a stress-producing layer 214).

[0124] The present invention thus relates to a method for separating solid-body slices 21 from a donor substrate 22. Here, the method according to the invention comprises the following steps:

[0125] providing a donor substrate 22, producing modifications 210 in the interior of the donor substrate 22 by means of LASER beams 212, wherein the LASER beams 212 penetrate the donor substrate 22 over a planar surface 216 of the donor substrate 22, wherein the totality of the LASER beams 212 is inclined relative to the planar surface 216 of the donor substrate 22 in such a way that a first portion 236 of the LASER beams 212 penetrates the donor substrate 22 at a first angle 238 to the planar surface 216 of the donor substrate 22 and at least one further portion 240 of the LASER beams 212 penetrates the donor substrate 22 at a second angle 242 to the planar surface 216 of the donor substrate 22, wherein the value of the first angle 238 differs from the value of the second angle 242, wherein the first portion 236 of the LASER beams 212 and the further portion 240 of the LASER beams 212 are focused in the donor substrate 22 in order to produce the modification 210, wherein the solid-body slice 21 is detached from the donor substrate 22 by the produced modifications 210 or a stress-producing layer 214 is produced or arranged on the planar surface 216 of the donor substrate and mechanical stresses are produced in the donor substrate 22 by means of a thermal treatment of the stress-producing layer 214, wherein a crack 220 for separating a solid-body layer 21 is created by the mechanical stresses and propagates along the modifications 210.

[0126] FIG. 10 shows a further variant of the method according to the invention. By means of a comparison of the first and the fifth illustration, it can be seen that the modifications 210 produced by means of the LASER beams 212, in the case of a planar surface 216, can be produced closer to the edge 244 than if the tip of the edge 217 is removed from the surface 216, as is shown in the fifth illustration. The LASER beams 212 here penetrate the donor substrate 22 similarly to the production of a modification explained with reference to FIG. 9.

[0127] The second illustration of FIG. 10 shows the production of an indentation 26 starting from a peripheral surface 24 towards the centre Z of the donor substrate 22, wherein the indentation is produced by means of ablation LASER beams 28 of an ablation LASER (not shown). The ablation LASER beams here preferably evaporate the material of the donor substrate 22 in order to produce the indentation 26.

[0128] Illustration 3 of FIG. 10 corresponds substantially to illustration 3 of FIG. 9, wherein merely the form of the indentation here is not asymmetrical, but instead is symmetrical. In accordance with this illustration, a stress-producing layer 214 is thus likewise produced or arranged on the donor substrate 22 and is thermally treated, in particular by means of liquid nitrogen, in order to produce mechanical stresses for initiating a crack 220.

[0129] Illustration 4 of FIG. 10 shows the solid-body slice 21 split off from the donor substrate 2, with the stress-producing layer still arranged on said solid-body slice.

[0130] It can also be seen from illustration 5 of FIG. 10 that in the case of a donor substrate 22 of which the tip of the edge 217 is processed, the indentation 26 to be produced by means of ablation LASER beams 28 must reach further in the direction of the centre of the donor substrate 22 than if the tip of the edge 217 is not processed. Here, however, it is also conceivable that the indentation is not produced by means of ablation LASER beams 28, but instead by means of a grinding tool 222 (as is known for example from FIG. 9).

[0131] FIG. 11 shows an arrangement in accordance with which a LASER beam 212 is oriented parallel to the longitudinal axis L. This illustration additionally or alternatively also shows a LASER beam 260 inclined at an angle al relative to the longitudinal axis L. Both LASER beams 212 and 260 can serve here for the production of the modifications 210, by means of which a detachment region 211 is predefined. It is conceivable here that a plurality of the modifications 210 are produced by the LASER beam 212, which is not inclined relative to the longitudinal axis L, and that the modifications 210 in the edge region, that is to say at a distance of less than 10 mm, in particular of less than 5 mm or of less than 2 mm or of less than 1 mm or of less than 0.5 mm from the peripherally extending surface (peripheral surface), are produced by the LASER beam 260 inclined relative to the longitudinal axis L.

[0132] Alternatively, it is also conceivable that all modifications 210 of the detachment region or the plurality of modifications 210 of the detachment region 211 are produced by the LASER beam 260 inclined at an angle 1 relative to the longitudinal axis L.

[0133] Additionally or alternatively, within the sense of the present invention, the modifications 210 in the edge region can be produced by a further LASER beam 262, 264 inclined relative to the longitudinal axis L of the donor substrate 22, wherein this LASER beam preferably penetrates the donor substrate 22 over a peripheral surface of the donor substrate 22. It can be seen from the illustration that a LASER beam 262, for production of the modifications 210 in the edge region, can be introduced into the donor substrate 22 over the peripheral surface for example at an angle 2, which is greater than 0 and smaller than 90, relative to the detachment region 211. It can also be seen from the illustration that a LASER beam 264, in order to produce the modifications 210, can be introduced into the donor substrate 22 over the peripheral surface of the donor substrate 22 in the direction of extent of the detachment region 211. Here, the LASER beam 264 is preferably inclined at an angle 3, between 80 and 100, in particular 90 or substantially 90, relative to the longitudinal axis L of the donor substrate 22.

[0134] A modification 210 can thus be produced in the region of the edge by one of the LASER beams 260, 262, 264.

[0135] Furthermore, in accordance with the invention, the statements provided with reference to FIG. 9 can be applied or transferred similarly to the subjects shown in FIG. 211, and vice versa.

[0136] FIG. 13a shows a detachment region 211 produced just short from the edge region. FIG. 13a also shows the production of modifications by means of a LASER beam 264. A plurality of modifications 210 are preferably produced in the radial direction by the LASER beam 264, in particular over a line, with increasingly greater distances from the centre or an axis of rotation (which extends preferably orthogonally to the planar surface 216 of the donor substrate 22) of the donor wafer 22.

[0137] FIG. 13b schematically shows a state following the production of the modifications 210. In accordance with this illustration the detachment region 211 is formed as a modification layer extending completely in the interior of the donor wafer 22.

[0138] FIGS. 14a and 14b show two variants for producing modifications 210 by means of LASER beams introduced over the peripheral surface.

[0139] In accordance with FIG. 14a, a multiplicity of modifications 210 are produced over the same penetration point, through which the LASER beams 264 penetrate the donor substrate 22. The LASER beams are focused into the donor substrate 22 at different depths in the radial direction in order to produce the modifications 210. The modifications 210 are preferably produced with decreasing penetration depth of the LASER beams or with increasingly shorter distance of the focus point from the penetration point.

[0140] FIG. 14b shows the filament-like production of modifications. The modifications 210 produced in the form of filaments are longer then a multiple of their cross-sectional extent, in particular for example 10 times, 20 times, or 50 times longer.

[0141] FIG. 15 shows a LASER device 246, an aberration means 247, and a sectional illustration of a donor substrate 2. The detailed illustration of FIG. 15 shows the LASER beam 212 penetrating the donor wafer 22 over the curved peripheral surface of the donor wafer 22, wherein the course of the radiation adapted by means of the aberration means 247 is illustrated by the dashed lines.

[0142] The present invention therefore relates to a method for separating solid-body slices 21 from a donor substrate 22. The method according to the invention comprises the following steps: providing a donor substrate 22, producing at least one modification 10 in the interior of the donor substrate 2 by means of at least one LASER beam 212, wherein the LASER beam 212 penetrates the donor substrate 22 over a planar surface 216 of the donor substrate 22, wherein the LASER beam 212 is inclined relative to the planar surface 216 of the donor substrate 22, in such a way that it penetrates the donor substrate at an angle that is unequal to 0 or 180 relative to the longitudinal axis of the donor substrate, wherein the LASER beam 212 is focused in the donor substrate 22 in order to produce the modification 210, wherein the solid-body slice 21 is detached from the donor substrate 22 by the produced modifications 210 or a stress-producing layer 214 is produced or arranged on the planar surface 216 of the donor substrate 22 and mechanical stresses are produced in the donor substrate 22 by a thermal treatment of the stress-producing layer 214, wherein a crack 220 for separating a solid-body layer 21 is produced by the mechanical stresses and propagates along the modifications 210.