Method for reducing the thickness of solid-state layers provided with components

Patent metadata

Field	Value
Publication number	US-11869810-B2
Application number	US-201816606540-A
Country	US
Kind code	B2
Filing date	Jan 15, 2018
Priority date	Apr 20, 2017
Publication date	Jan 9, 2024
Grant date	Jan 9, 2024

Abstract

The invention relates to a method for separating at least one solid-state layer ( 4 ) from at least one solid ( 1 ). The method according to the invention includes the steps of: producing a plurality of modifications ( 9 ) by means of laser beams in the interior of the solid ( 1 ) in order to form a separation plane ( 8 ); producing a composite structure by arranging or producing layers and/or components ( 150 ) on or above an initially exposed surface ( 5 ) of the solid ( 1 ), the exposed surface ( 5 ) being part of the solid-state layer ( 4 ) to be separated; introducing an external force into the solid ( 1 ) in order to create stresses in the solid ( 1 ), the external force being so great that the stresses cause a crack to propagate along the separation plane ( 8 ), wherein the modifications for forming the separation plane ( 8 ) are produced before the composite structure is produced.

First claim

The invention claimed is:

1. A method of separating a solid-state layer from a solid-state body, comprising:
generating a plurality of modifications by laser beams within the solid-state body to form a detachment region, wherein the laser beams are adjustable as a function of at least two parameters;
after generating the plurality of modifications, generating a composite structure by arranging or generating layers and/or components on or above an initially exposed surface of the solid-state body, wherein the exposed surface is part of the solid-state layer to be separated; and
introducing an external force into the solid-state body to generate stresses in the solid-state body or generating an internal force in the solid-state body, wherein a strength of the external or internal force is sufficient for crack propagation to occur along the detachment region,
wherein a first parameter of the at least two parameters is an average refractive index of a material of the solid-state body or a refractive index of the material of the solid-state body in a region of the solid-state body to be traversed to generate a defined modification by the laser beams,
wherein a second parameter of the at least two parameters is a processing depth in the region of the solid-state body to be traversed to generate the defined modification by the laser beams.

2. The method of claim 1 , wherein introducing the external force into the solid-state body comprises:
arranging a receiving layer on an exposed surface of the composite structure or of the solid-state layer to be separated, wherein the receiving layer comprises a polymer material;
subjecting the receiving layer to thermal stress for generation of stresses in the solid-state body, including cooling the receiving layer to a temperature below ambient temperature,
wherein the cooling comprises subjecting the polymer material of the receiving layer to a glass transition,
wherein the stresses cause a crack to propagate in the solid-state body along the detachment region,
wherein the first solid-state layer separates from the solid-state body along the crack.

3. The method of claim 1 , further comprising:
disposing a diffractive optical element (DOE) in a pathway of the laser beams prior to penetration of the laser beams into the solid-state body, wherein the laser beams is split by the DOE into multiple light pathways for generation of multiple foci.

4. The method of claim 3 , wherein the DOE brings about an image field curvature over a length of 200 μm of not more than 50 μm, not more than 30 μm, not more than 10 μm, not more than 5 μm, or not more than 3 μm.

5. The method of claim 3 , wherein the DOE simultaneously generates 2 or more foci to change one or more material properties of the solid-state body.

6. The method of claim 1 , further comprising:
moving the solid-state body relative to a laser exposure device;
successively generating the laser beams by the laser exposure device for generating at least one modification in each case; and
adjusting the laser exposure device for defined focusing of the laser beams and/or for adjustment of laser energy, depending on at least one parameter.

7. The method of claim 1 , wherein the laser beams penetrate into the solid-state body via a planar surface of the solid-state body, wherein at least one of the laser beams is inclined relative to the planar surface of the solid-state body such that the at least one laser beam enters the solid-state body at an angle other than 0° or 180° to a longitudinal axis of the solid-state body, wherein the at least one laser beam is focused to generate a modification in the solid-state body.

8. The method of claim 1 , further comprising:
removing material from the solid-state body proceeding from a surface extending in a circumferential direction of the solid-state body in a direction of a center of the solid-state body.

9. The method of claim 1 , wherein the solid-state body has crystal lattice planes inclined relative to a planar main surface, wherein the planar main surface forms a boundary on one side in a longitudinal direction of the solid-state body, wherein a crystal lattice plane normal is inclined in a first direction relative to a main surface normal, wherein the modifications are a change in a material property of the solid-state body, wherein the change in the material property forms a linear design at least in sections in the solid-state body by changing a site of penetration of the laser beams, wherein the change in the material property is generated in a generation plane or in the detachment region, wherein the crystal lattice planes of the solid-state body are in an inclined alignment relative to the generation plane or the detachment region, wherein the linear design is inclined relative to a cutting line that arises at a point of intersection between the generation plane or the detachment region and the crystal lattice plane, wherein the changed material property results in tearing of the solid-state body in a form of subcritical cracks, wherein the external force introduced into the solid-state body connects the subcritical cracks such that the solid-state layer detaches from the solid-state body with connection of the subcritical cracks.

10. The method of claim 1 , wherein the laser beams are generated with pulse lengths of less than 5 ns, and wherein the laser beams are generated with pulse energies between 100 nJ and 1 mJ.

11. The method of claim 1 , wherein the detachment region describes at least a three-dimensional outline and/or wherein the detachment region is uneven within the solid-state body.

12. The method of claim 1 , further comprising:
determining the first parameter by spectral reflection; and/or
determining the second parameter by determining topography using a confocal-chromatic distance sensor,
wherein data for the first parameter and for the second parameter are provided in a data storage device and sent to a control device at least prior to the generation of the modifications,
wherein the control device adjusts a laser exposure device that generates the laser beams as a function of a respective location of the modification to be produced,
wherein the control device, for adjustment of the laser exposure device, processes distance data to give a distance parameter,
wherein the distance parameter gives the distance of the respective location at which laser beams generate the respective modification by being introduced into the solid-state body at a time of generation of the modification from the laser exposure device,
wherein the distance data are detected by a sensor device.

13. The method claim 12 , wherein the laser exposure device is adjusted as a function of a determination of the first parameter and of the second parameter during the generation of the modification, by determining the refractive index and determining the topography.

14. The method of claim 1 , further comprising:
generating a second group of modifications by additional laser beams to define a second detachment plane, wherein the detachment plane and the second detachment plane are in an orthogonal alignment relative to one another; and
dividing the solid-state layer separated from the solid-state body along the second detachment plane to individualize solid-state elements.

15. The method of claim 1 , further comprising:
pressing at least one pressurizing element of a pressurizing device against at least a predetermined proportion of a stress generation layer for pressing of the stress generation layer onto the surface of the solid-state body,
wherein the pressurizing element is p

Assignees

• Siltectra Gmbh

Inventors

• Swoboda Marko
• Rieske Ralf
• Beyer Christian
• Richter Jan

Classifications

• H10P95/112 Primary

  leaving a reusable substrate, e.g. epitaxial lift off · CPC title

• H10P52/00

  Grinding, lapping or polishing of wafers, substrates or parts of devices · CPC title

• H10P90/12

  Preparing bulk and homogeneous wafers · CPC title

• H10D30/66

  Vertical DMOS [VDMOS] FETs · CPC title

• H10D62/8325

  Silicon carbide · CPC title