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 ).

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 D 1 ,   the bonding wafer ( 2 ) has a second thickness D 2 ,   the separation part ( 14 ) has a third thickness D 3 , and   the connection part ( 16 ) has a fourth thickness D 4 ,   wherein the thickness D 1  is greater than the sum of the thicknesses D 3  and D 4 ,   wherein the sum of the thicknesses D 3  and D 4  is greater than the thickness D 3 ,   wherein the thickness D 3  is greater than the thickness D 2  by a thickness DL.   
     
     
         5 . The method according to  claim 4 ,
 characterised in that   the thickness DL is less than 200 μm, in particular less than 100 μm, 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 −1  and preferably less than 1 cm −1  and particularly preferably less than 0.1 cm −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 μm, 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 μJ and preferably more than 10 μJ 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 −1  and preferably less than 1 cm −1  and particularly preferably less than 0.1 cm −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 −1  and preferably less than 1 cm −1  and particularly preferably less than 0.1 cm −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.