PRIOR SUBSTRATE, WAFER COMPOSITE, AND CRYSTALLINE SUBSTRATE AND METHODS FOR MANUFACTURING SEMICONDUCTOR DEVICES - Patent application

Abstract

To provide a parent substrate, a wafer composite and methods of manufacturing a crystalline substrate and a semiconductor device.SOLUTION: There is provided a parent substrate (100) that includes a central region (110) and an edge region (180). The edge region (180) surrounds the central region (110). A detachment layer (150) is formed in the central region (110). The detachment layer (150) extends parallel to main surfaces (101, 102) of the parent substrate (100). The detachment layer (150) includes a modified substrate material. A groove (190) is formed in the edge region (180). The groove (190) laterally encloses the central region (110). The groove (190) runs vertically and / or tilted to the detachment layer (150).SELECTED DRAWING: Figure 5C

Description

[Technical field]

[0001] The present disclosure relates to methods of manufacturing crystalline substrates, particularly crystalline device substrates, methods of manufacturing semiconductor devices, crystalline substrates, and wafer composites including crystalline substrates. [Background technology]

[0002] Crystalline substrates, such as crystalline semiconductor substrates, are typically available in standard sizes, with the standards specifying the diameter and thickness. In response, attempts have been made to reduce the final thickness of thin semiconductor devices to improve device characteristics. For example, for power semiconductor devices with vertical load current between the front and back sides, a thinner semiconductor die may result in a lower on-state resistance. Other attempts aim to reduce substrate costs by using thin semiconductor slices as a base for epitaxial growth. For example, splitting methods split thin slices horizontally from a semiconductor boule or split standard wafers horizontally (wafer twinning). Crystalline substrates, such as semiconductor wafers, may be slightly chamfered, e.g., chamfered and / or rounded, to avoid chipping and reduce the occurrence of breakage at sharp edges of the crystalline substrate. Summary of the Invention [Problem to be solved by the invention]

[0003] There is a continuing need to improve the manufacture of crystalline substrates and semiconductor devices. [Means for solving the problem]

[0004] An embodiment of the present disclosure relates to a method for manufacturing a device substrate. A parent substrate is provided that includes a central region and an edge region. The edge region surrounds the central region. A release layer is formed in the central region. The release layer extends parallel to a major surface. The release layer comprises a modified substrate material. A groove is formed in the edge region. The groove laterally surrounds the central region. The groove extends perpendicularly and / or at an angle to the release layer.

[0005] A further embodiment of the present disclosure relates to a parent substrate. The parent substrate includes a central region and an edge region. The edge region surrounds the central region. Grooves in the edge regions laterally surround the central region. The grooves extend perpendicularly and / or at an angle to the release layer. In the central region, the release layer extends parallel to the major surface and terminates in the grooves. The release layer comprises a modified substrate material.

[0006] The accompanying drawings are included to provide a further understanding of the embodiments, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of a crystalline substrate, a wafer composite, a method of manufacturing a crystalline substrate, and a method of manufacturing a semiconductor device, and together with the description, serve to explain the principles of the embodiments. Further embodiments are described in the following detailed description and claims. [Brief description of the drawings]

[0007] [Figure 1A] 1 shows a schematic vertical cross-sectional view of a crystalline parent substrate to illustrate a method of fabricating a device substrate using grooves in the edge regions and a release layer in the central region according to one embodiment. [Figure 1B] 1 shows a schematic vertical cross-sectional view of a crystalline parent substrate to illustrate a method of fabricating a device substrate using grooves in the edge regions and a release layer in the central region according to one embodiment. [Figure 1C] 1 shows a schematic vertical cross-sectional view of a crystalline parent substrate to illustrate a method of fabricating a device substrate using grooves in the edge regions and a release layer in the central region according to one embodiment. [Diagram 2]2 is a schematic plan view of a master substrate including grooves in its edge regions according to one embodiment; [Diagram 3] 1 is a schematic plan view of a portion of a parent substrate from a semiconductor material including a groove between a central region and an edge region according to one embodiment; [Figure 4A] 1A-1D are schematic side cross-sectional views of edge regions of a master substrate having grooves of various shapes, according to one embodiment. [Figure 4B] 1A-1D are schematic side cross-sectional views of edge regions of a master substrate having grooves of various shapes, according to one embodiment. [Figure 4C] 1A-1D are schematic side cross-sectional views of edge regions of a master substrate having grooves of various shapes, according to one embodiment. [Figure 4D] 1A-1D are schematic side cross-sectional views of edge regions of a master substrate having grooves of various shapes, according to one embodiment. [Figure 4E] 1A-1D are schematic side cross-sectional views of edge regions of a master substrate having grooves of various shapes, according to one embodiment. [Figure 5A] 1A-1C are schematic vertical cross-sectional views of a mother substrate based on a semiconductor material and of a wafer composite including the mother substrate to illustrate a method of manufacturing a semiconductor device according to an embodiment. [Figure 5B] 1A-1C are schematic vertical cross-sectional views of a mother substrate based on a semiconductor material and of a wafer composite including the mother substrate to illustrate a method of manufacturing a semiconductor device according to an embodiment. [Figure 5C] 1A-1C are schematic vertical cross-sectional views of a mother substrate based on a semiconductor material and of a wafer composite including the mother substrate to illustrate a method of manufacturing a semiconductor device according to an embodiment. [Figure 5D] 1A-1C are schematic vertical cross-sectional views of a mother substrate based on a semiconductor material and of a wafer composite including the mother substrate to illustrate a method of manufacturing a semiconductor device according to an embodiment. [Figure 5E] 1A-1C are schematic vertical cross-sectional views of a mother substrate based on a semiconductor material and of a wafer composite including the mother substrate to illustrate a method of manufacturing a semiconductor device according to an embodiment. [Figure 5F]1A-1C are schematic vertical cross-sectional views of a mother substrate based on a semiconductor material and of a wafer composite including the mother substrate to illustrate a method of manufacturing a semiconductor device according to an embodiment. [Figure 5G] 1A-1C are schematic vertical cross-sectional views of a mother substrate based on a semiconductor material and of a wafer composite including the mother substrate to illustrate a method of manufacturing a semiconductor device according to an embodiment. [Figure 6A] 1 is a schematic vertical cross-sectional view of a mother substrate based on a semiconductor material and of a wafer composite including the mother substrate to illustrate a method of manufacturing a semiconductor device according to an embodiment including layer transfer and epitaxial growth; FIG. [Figure 6B] 1 is a schematic vertical cross-sectional view of a mother substrate based on a semiconductor material and of a wafer composite including the mother substrate to illustrate a method of manufacturing a semiconductor device according to an embodiment including layer transfer and epitaxial growth; FIG. [Figure 6C] 1 is a schematic vertical cross-sectional view of a mother substrate based on a semiconductor material and of a wafer composite including the mother substrate to illustrate a method of manufacturing a semiconductor device according to an embodiment including layer transfer and epitaxial growth; FIG. [Figure 7A] 1 is a schematic vertical cross-sectional view of a mother substrate based on a semiconductor material and of a wafer composite including the mother substrate to illustrate a method of manufacturing a semiconductor device according to an embodiment relating to the formation of a groove on the backside of the substrate; [Figure 7B] 1 is a schematic vertical cross-sectional view of a mother substrate based on a semiconductor material and of a wafer composite including the mother substrate to illustrate a method of manufacturing a semiconductor device according to an embodiment relating to the formation of a groove on the backside of the substrate; [Figure 8A] 1 is a schematic side cross-sectional view of a portion of a wafer composite according to an embodiment with reference to an edge trim; [Figure 8B] 1 is a schematic side cross-sectional view of a trimming tool according to an embodiment with reference to an edge trim; [Figure 9A] 13 is a schematic vertical cross-sectional view of a portion of a wafer composite according to a further embodiment with reference to the formation of grooves from the front side. [Figure 9B]13 is a schematic vertical cross-sectional view of a portion of a wafer composite according to a further embodiment with reference to the formation of grooves from the front side. [Figure 10] FIG. 2 is a schematic vertical cross-sectional view of a wafer composite according to one embodiment with reference to front side processing. [Figure 11A] 1 is a schematic vertical cross-sectional view of a wafer composite according to an embodiment with reference to backside processing; [Figure 11B] 1 is a schematic vertical cross-sectional view of a wafer composite according to an embodiment with reference to backside processing; [Figure 11C] 1 is a schematic vertical cross-sectional view of a wafer composite according to an embodiment with reference to backside processing; [Figure 11D] 1 is a schematic vertical cross-sectional view of a wafer composite according to an embodiment with reference to backside processing; [Figure 12] FIG. 13 is a schematic block diagram of a tool assembly suitable for performing front side and / or back side processing, according to a further embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] In the following detailed description, reference is made to the accompanying drawings, which form a part of this specification and which illustrate, by way of example, specific embodiments in which the device substrate, the wafer composite, the method of manufacturing the device substrate, and the method of manufacturing a semiconductor device may be implemented. It should be understood that further embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. For example, features illustrated or described for one embodiment may be used on or in conjunction with further embodiments to obtain still further embodiments. The present disclosure is intended to include such modifications and variations. Although the examples are described using specific terms, this should not be construed as limiting the scope of the appended claims. The drawings are not to scale and are for illustrative purposes only. Corresponding elements are designated by the same reference numerals in different drawings unless otherwise specified.

[0009] The terms "having," "containing," "including," "comprising," and the like are open in that these terms indicate the presence of stated structures, elements, or features, but do not exclude additional elements or features. The articles "a," "an," and "the" are intended to include the plural as well as the singular, unless the context clearly indicates otherwise.

[0010] Ranges given for parameters are inclusive: for example a range for a parameter y from a to b means a≦y≦b. A parameter y having a value of at least c means c≦y, and a parameter y having a value at most d means y≦d.

[0011] The main components of a layer or structure made of a compound or alloy are those elements whose atoms form the compound or alloy, for example nickel and silicon are the main components of a nickel silicide layer, and copper and aluminum are the main components of a copper aluminum alloy.

[0012] The term "on" should not be construed to mean only "directly on." Rather, when an element is "on" another element (e.g., a layer is "on" another layer, or "on" a substrate), additional components (e.g., additional layers) may be disposed between the two elements (e.g., when a layer is "on" a substrate, additional layers may be disposed between the layer and the substrate).

[0013] The term "power semiconductor device" refers to a semiconductor device having a high voltage blocking capability, e.g., 30V, 100V, 600V, 3.3kV, or more, and a nominal on-state current or forward current of at least 1A, e.g., 10A, or more.

[0014] According to an embodiment, a method of manufacturing a device substrate may include providing a parent substrate. The parent substrate may be crystalline. That is, at least 90%, or even at least 95%, of the parent substrate may comprise a crystalline material, such as a polycrystalline material or a monocrystalline material. The parent substrate may include a central region and an edge region. The edge region may surround the central region. For example, at least 60% (or at least 70%, or at least 80%) of the parent substrate may be part of the central region.

[0015] A parent substrate (German: "Ausgangssubstrat") may be a crystalline ingot (boule) of monocrystalline material, or a wafer-sized slice (e.g., wafer) of monocrystalline material. The parent substrate may comprise exclusively monocrystalline material (except for the modified substrate material in the exfoliation layer), or may comprise, in addition to a major portion formed from monocrystalline material, the modified substrate material in the exfoliation layer, and / or structures of other materials, such as conductive structures and / or insulating structures.

[0016] The monocrystalline material may be a ceramic, such as α-Al2O3 (sapphire), or a semiconductor material, which may be, for example, any of the group IV element semiconductors, such as silicon (Si) or germanium (Ge), any of the group IV compound semiconductors, such as silicon carbide (SiC) or silicon germanium (SiGe), or any of the group III / V compound semiconductors, such as gallium arsenide (GaAs) or gallium nitride (GaN).

[0017] For example, the material of the parent substrate may be 15R-SiC (15R polytype of silicon carbide), or hexagonal polytype of silicon carbide, such as 2H-SiC, 4H-SiC, or 6H-SiC. In addition to the main components silicon and carbon, the parent substrate may contain dopant atoms, such as nitrogen N, phosphorus P, beryllium Be, boron B, aluminum Al, and / or gallium Ga. Furthermore, the parent substrate may contain unwanted impurities, such as hydrogen, fluorine, and / or oxygen.

[0018] For example, the parent substrate may be a virgin semiconductor wafer or a processed semiconductor wafer. A virgin semiconductor wafer may be a semiconductor wafer after it has been obtained from a crystalline ingot, for example by sawing, and before any pre-processing specific to a particular type of semiconductor device. For example, a virgin semiconductor wafer may have undergone a non-specific process, for example, edge rounding, chamfering, heat treatment, and / or a process for forming a surface oxide. A processed semiconductor wafer may be a semiconductor wafer after it has undergone at least one device-specific process, for example, a blanket doping or patterning process. A processed semiconductor wafer may include spatially separated doped regions, insulator structures, and / or conductive structures including polycrystalline semiconductor materials, metals and / or metal compounds.

[0019] The parent substrate may have two essentially parallel major surfaces of the same shape and size and a lateral outer surface connecting the edges of the two major surfaces. The parent substrate may extend laterally in a laterally spanning plane. Accordingly, the parent substrate may have a surface extent along two lateral directions (hereinafter also referred to as horizontal directions). The parent substrate may have a thickness along a vertical direction perpendicular to the lateral directions.

[0020] As used herein and hereinafter, a first and second surface may be "essentially parallel" if the average plane approximating the first surface and the average plane approximating the second surface form an angle of at most 5 degrees (or at most 2 degrees).

[0021] The major surfaces may be perfectly oriented in a plane. The major surfaces and the laterally outer surfaces may be connected via right-angled edges. Alternatively, the laterally outer surfaces may be chamfered, e.g. chamfered and / or rounded, in the direction of one of the major surfaces or in the direction of both of the major surfaces.

[0022] The laterally outer surface may include a vertical portion extending along a vertical direction. In addition to the vertical portion, the laterally outer surface may include one or more chamfered portions between the vertical portion and a first major surface of the major surfaces. In addition, the laterally outer surface may further include one or more chamfered portions between the vertical portion and a second major surface of the major surfaces. Each of the chamfered portions may have a different inclination angle with respect to the vertical portion. Alternatively, the laterally outer surface may include a rounded portion between the vertical portion and at least a first major surface of the major surfaces. The laterally outer surface may include one or more rounded portions between the vertical portion and the chamfered portion, between adjacent chamfered portions, and / or between the chamfered portion and the corresponding major surface.

[0023] The first major surface on the front side and the second major surface on the back side may have a polygonal (e.g., rectangular or hexagonal) shape with or without rounded edges, or a circular shape with or without notches or flats along the circumference.

[0024] In vertical cross section, the laterally outer surface may be flat, may be outwardly curved, and / or may include a chamfer at at least one of the transitions to the major surface, which may be chamfered and / or rounded.

[0025] The major surfaces may extend laterally in a laterally spanning plane and accordingly the parent substrate may have a lateral extent along two orthogonal lateral directions and a thickness along a vertical direction perpendicular to the lateral directions.

[0026] The mother substrate may be a semiconductor wafer, and the diameter and thickness of the mother substrate may correspond to production standards for semiconductor wafers. The diameter of the mother substrate may be 4 inches (100 mm), 6 inches (150 mm), 7 inches (175 mm), 200 mm (8 inches), or 300 mm (12 inches).

[0027] The central region of the parent substrate may be a circular or approximately circular region. If the parent substrate is a virgin semiconductor wafer, at least the central region may be uniformly doped. If the parent substrate is a preprocessed semiconductor wafer, the central region may include a plurality of laterally separated device regions, each of which may include a plurality of doped regions, conductive structures, and / or insulating structures. The conductive structures and / or insulating structures may be formed on the parent substrate and / or may extend from the first major surface into the parent substrate. A grid-like kerf region may separate the device regions in the central region of the parent substrate.

[0028] The edge region may be between the central region and the lateral outer surface of the parent substrate. The edge region may extend from the central region to the lateral outer surface. The edge region may be free of device regions. The edge region may completely surround the central region. The edge region may have a substantially uniform width. For example, the edge region may have an average width of at least 100 μm, at most 3 mm, such as at most 1 mm, or at most 500 μm. It may be possible for the edge region to include or be defined by a chamfered (e.g., chamfered and / or rounded) region along the lateral outer surface of the parent substrate. The chamfered region of the parent substrate may be defined by the lateral extent of the chamfered portion of the lateral outer surface. For example, the edge region may, for example, exclusively include a portion of the lateral outer surface, such as a chamfer of the lateral outer surface.

[0029] A release layer may be formed in the central region. The release layer may extend parallel to at least one of the major surfaces of the parent substrate, or parallel to both major surfaces. The release layer may extend laterally and / or parallel to the laterally.

[0030] The grooves may be formed in the edge region before, after, or during the formation of the release layer. It may also be possible that a portion of the groove is formed before the formation of the release layer and a further portion of the groove is formed after the formation of the release layer, or vice versa. The grooves may consist of a single connected groove or may consist of multiple sub-grooves horizontally separated from each other. The grooves may extend in an outward direction from the layer in which the release layer is formed.

[0031] The grooves may extend from one of the major surfaces to or beyond the release layer. The vertical extent of the grooves may be at least 80%, such as at least 95%, and up to 120%, such as 105%, of the distance between the release layer and its major surface on which the grooves are formed. For example, the vertical extent of the grooves and the distance between the release layer and its major surface on which the grooves are formed may be equal or approximately equal.

[0032] In some embodiments, the groove may extend into the parent substrate from at least one of the major surfaces, or may extend into the parent substrate from a portion of the laterally outer surface that is closer to one of the major surfaces. The groove may extend perpendicularly and / or tilted and / or laterally relative to the release layer. Herein and hereinafter, "tilted" may mean that the groove (e.g., the major axis of the groove) and the release layer and / or the lateral direction form an angle of at least 5 degrees and at most 90 degrees. For example, the groove and the release layer form an angle in the range of 5 degrees to 85 degrees, such as in the range of 5 degrees to 45 degrees.

[0033] Angles of 90 degrees are also contemplated for "vertical" grooves. The major axis of a groove may be the direction along which the groove extends primarily away from the central region. For example, the groove may have its maximum extent in the direction away from the central region along the major axis. The major axis may extend perpendicularly or at least obliquely to the circumferential direction of the parent substrate.

[0034] The groove may include an inner groove sidewall and an outer groove sidewall. The inner groove sidewall may be disposed closer to the central region than the outer groove sidewall. In some embodiments, the groove may terminate in a release layer, or the release layer may terminate in the groove. The release layer may contact the inner groove sidewall. According to some embodiments, the groove may be tapered, and a blind end of the groove may meet an outer edge of the release layer.

[0035] The release layer may include modified substrate material. The modified substrate material may form a plurality of laterally separated modified zones. Each of the modified zones may be configured along a modified line. In some embodiments, the release layer may include a plurality of laterally separated modified zones configured along modified lines and separated by unmodified substrate material. For example, each of the modified zones may include a plurality of modified regions resulting from an essentially single irradiation of the laser beam into the parent substrate. At least some or all of the modified regions may be connected to and / or overlap their adjacent modified regions. Additionally or alternatively, at least some or all of the adjacent modified regions may be separated from each other by unmodified substrate material. That is, at least some or all of the modified regions may not overlap adjacent modified regions. The modified lines may run parallel to each other. The modified zones (e.g., modified lines) may terminate at the inner groove sidewall. According to another embodiment, the modified zone and the bottom of the groove may merge.

[0036] The modified substrate material may comprise a major component of the material of the parent substrate. For example, the modified substrate material may have a different phase than the unmodified material, e.g., a different phase than a monocrystalline phase. For example, the modified zone may comprise a major component of the substrate material in polycrystalline form, in amorphous form, and / or as a mixture of the basic components of the substrate material. For example, the modified substrate material may comprise elemental silicon in amorphous and / or polycrystalline form, and / or carbon in amorphous and / or polycrystalline form.

[0037] According to some embodiments, the release layer may include a highly porous structure, e.g., at least 20% porous, and / or a structure having implantation-induced crystalline damage, which may include, for example, hydrogen-modified crystalline defects.

[0038] The groove may laterally surround the central region. For example, the groove may completely surround the central region laterally. The groove may form a frame for the central region. The groove may have a substantially uniform radial extent (width) along the complete circumference. The groove may have a substantially uniform depth along the complete circumference. If the groove comprises multiple sub-grooves, the sub-grooves may have substantially equal widths and / or equal depths along the complete circumference of the central region. In a horizontal plane, the groove may include a circular portion or may approximate a substantially circular portion with orthogonal line portions.

[0039] For example, the groove may form a complete circle in the horizontal plane. The diameter of the circle may be smaller than the maximum inscribed circle (German: "groesster eingeschriebener Kreis") of the horizontal substrate shape, which may include one or more flats along the periphery. The groove may be vertical or inclined towards the centre of the circle, and the angle between the main axis of the groove and the horizontal plane may be in the range of 5 degrees to 45 degrees, for example 15 degrees to 45 degrees. The groove may be exclusively formed in the part of the edge region whose main surfaces run parallel to one another. Alternatively, the groove may be partially or completely formed in the chamfered and / or rounded part of the edge region. For example, the groove may be entirely or partially formed in the lateral outer surface.

[0040] According to other embodiments, the groove may include one or more straight portions and one or more circular arcs, which are complementary to each other to form a closed shape. The diameter of the circular arcs may be smaller, equal or larger than the maximum inscribed circle of the horizontal substrate shape, which shape may include one or more flats along the periphery. Each of the straight portions of the groove may extend parallel to one of the flats. The groove may be vertical or inclined towards the center of the circle, and the angle between the main axis of the groove and the horizontal plane may be in the range of 5 degrees to 45 degrees, for example 15 degrees to 45 degrees. The groove may be exclusively formed in a part of the edge region, whose main surfaces extend parallel to each other. Alternatively, the groove may be partially or completely formed in a chamfered and / or rounded region of the edge region. For example, the groove may be entirely or partially formed in the lateral outer surface.

[0041] The groove may include an inner groove sidewall on a side located towards a central region (e.g., lateral center) of the parent substrate. The groove may be formed at a fixed distance from the central region. The distance between the groove and the central region may be uniform along the entire circumference. According to another embodiment, the inner groove sidewall may represent a boundary or transition between the central region and the edge region. The groove width may be at least 10 μm. The groove depth (e.g., the extent of the groove along the major axis) may be in the range of 10 μm to several hundred μm.

[0042] The combination of the circumferential groove and the exfoliation layer in contact with the inner groove sidewalls may then facilitate splitting the parent substrate into a device substrate and a reclaimed substrate, which separate along a splitting plane extending laterally through and / or along and / or essentially parallel to the exfoliation layer. The groove may avoid or at least attenuate edge effects that may adversely affect the formation of portions of the exfoliation layer proximate the lateral outer surface.

[0043] According to one embodiment, the mother substrate may be split along a splitting plane, for example at the exfoliation layer. The splitting plane may vertically separate the exfoliation layer into a portion above the splitting plane (e.g., a first mother substrate portion) and a portion below the splitting plane (e.g., a second mother substrate portion). The split separates the mother substrate into a first mother substrate portion (device substrate) and a second mother substrate portion (reclaimed substrate). The first mother substrate portion may include a mother substrate portion extending from the first major surface to the splitting plane. The second mother substrate portion may include a mother substrate portion extending from the splitting plane to the second major surface.

[0044] Thanks to the grooves, the splitting process can be independent of edge effects, which can have a negative impact on the yield of the splitting process. In addition, it is possible to define the shape of the lateral outer surface of the device substrate or the shape of the lateral outer surface of the reclaimed substrate via the shape of the grooves. It is also possible for the substrate parts whose lateral outer surface is not defined by the grooves to be formed by ring-shaped reinforcing parts. The reinforcing parts may have a larger vertical extent than the central part of the substrate part concerned.

[0045] That is, the device substrate resulting from the splitting process may have inherently chamfered edges along the lateral outer surfaces and / or may be formed with a reinforcing ring. The formation of the chamfered edges and / or reinforcing rings does not require additional processes and is already achieved by the splitting process alone. The chamfered edges may reduce the occurrence of chipping and breakage along the lateral outer surfaces, even in device substrates having thicknesses that are inaccessible to standard chamfering tools. The reinforcing rings may mechanically stabilize the device substrate after the splitting process.

[0046] Additionally or alternatively, the reclaimed substrate resulting from the splitting process may have inherently chamfered edges and / or may include stiffening rings that stabilize the reclaimed substrate after the splitting process. The lateral dimensions, e.g., diameter, of the reclaimed substrate may be similar to that of the parent substrate, such that reworking and / or reuse of the reclaimed substrate may use standard tools with no or only insignificant modifications to the settings of such standard tools.

[0047] For example, the grooves may be formed completely or partially in the lateral outer surface and may extend at an angle of about 45 degrees to 5 degrees relative to the horizontal, and the diameters of both the reclaimed and device substrates may be approximately the same. Both the device and reclaimed substrates may be handled in the same tool, and the reclaimed substrates may be further processed in much the same way as the device or parent substrates.

[0048] According to one embodiment, in the edge region, the distance between the major surfaces of the parent substrate may decrease with increasing distance to the lateral center of the parent substrate and / or with increasing distance to the central region. In other words, the parent substrate may be a semiconductor wafer, the lateral outer surface of which is chamfered at the transition to at least one of the major surfaces. The chamfer may include a chamfer, which may be rounded or not. The chamfer may contribute to reducing cracking and / or edge chipping effects during transportation or handling of the parent substrate. According to another embodiment, the distance between the major surfaces of the parent substrate may be constant in the edge region.

[0049] The circumferential groove can decouple the formation of the exfoliation layer from the effect of the chamfer on the formation process for the exfoliation layer. For example, due to the nature of the laser-induced damage layer formation (optical constraints and microcrack length), it may be difficult to make the laser-induced crystalline damage reach the lateral outer surface to a sufficient extent when forming the exfoliation layer containing the laser-induced crystalline damage. If the exfoliation layer does not reach the lateral outer surface to a sufficient extent, it may be difficult for the crack to penetrate from the lateral outer surface during the splitting process, and therefore the yield may be severe. The exfoliation layer may terminate at the circumferential groove, eliminating the need for the exfoliation layer to terminate at the lateral outer surface.

[0050] Other than edge trim processes that may remove semiconductor material starting from the lateral outer surface, circumferential grooves extending from one of the major surfaces into the parent substrate may be formed at an early stage of processing. In particular, standard tools for wafer processing on the front side may be used to form the grooves, such as a dicing tool that separates the device areas from each other, or an edge trim tool. The formation of the grooves can be easily integrated into existing manufacturing lines with little or moderate effort.

[0051] With the exception of horizontal layer etch processes that may remove adhesive material bonding the parent substrate to the auxiliary carrier, a circumferential groove extending from one of the major surfaces into the parent substrate can be formed without removing adhesive material and without adhesive material residue that may contaminate the parent substrate and / or the tools used to form the groove.

[0052] According to one embodiment, the grooves may extend into the mother substrate from a first major surface at the front side of the mother substrate. The front side may be the side of the substrate to be patterned, on which the front side metallization of the semiconductor device is formed, for example the source and gate electrodes of a power semiconductor device. In this case, the grooves may be formed with little or moderate additional effort, for example using any tool compatible with the pre-dicing process in the framework of the DBG (dicing before grinding) process. The yield of the division process may be significantly improved with only little or moderate additional effort. According to another embodiment, the grooves may extend into the mother substrate from a second major surface opposite to the front side of the mother substrate.

[0053] According to an embodiment, the groove may include an inner groove sidewall. The inner groove sidewall is located towards the lateral center and / or central region of the parent substrate. The inner groove sidewall may include a vertical or near vertical sidewall section. In the context, the terms "vertical" and "tilted" may refer to the orientation of the sidewall section with respect to the lateral direction. The release layer may cut the vertical sidewall section. In other words, the modified zone of the release layer, e.g. the release layer including the laser-induced crystal damage, may end at the vertical sidewall section.

[0054] The release layer may cut perpendicular or nearly perpendicular to the inner groove sidewalls, supporting the propagation of cracks originating from the inner groove sidewalls towards the lateral center of the parent substrate, allowing the splitting process to be performed reliably and with high yields.

[0055] According to an embodiment, the grooves may be spaced apart from the lateral outer surface of the parent substrate. In other words, the grooves may be formed at a certain distance from the lateral outer surface. For example, the grooves may be formed using a dicing blade and / or a laser ablation tool (e.g. a laser dicing tool) at a small additional cost. The opening of the grooves in the first or second major surface may have a width in the radial direction. The width of the opening of the grooves may be in the range of at least 10 μm (or at least 30 μm) to at most 1 mm, typically at most 300 μm, or at most 100 μm. For example, the opening of the grooves may have a width in the range of 30 μm to 60 μm. The vertical extent of the grooves may be selected such that the grooves reach the release layer. For example, the vertical extent of the grooves may be in the range of 10 μm to 200 μm, for example in the range of 20 μm to 120 μm (e.g. 60 μm to 120 μm, or 30 μm to 60 μm).

[0056] According to one embodiment, the groove may extend inwardly from the laterally outer surface. In other words, the groove forms a one-sided recess whose inner groove sidewall forms the only groove sidewall extending from the major surface into the parent substrate. The groove may start at the inner groove sidewall and have a substantially flat groove bottom extending from the inner groove sidewall to the laterally outer surface. The transition between the inner groove sidewall and the groove bottom may be curved. The radial extent of the groove corresponds to the distance from the inner groove sidewall to the outer periphery of the parent substrate. The radial extent of the groove may be at least 90% and at most 110% of the width of the edge region. For example, the radial extent of the groove may be in the range of at least 10 μm (or at least 30 μm) to at most 1 mm, typically at most 300 μm, or at most 100 μm. The vertical extent of the grooves may be in the range of 10 μm to 200 μm, typically in the range of 20 μm to 120 μm (eg, 60 μm to 120 μm, or 30 μm to 60 μm).

[0057] The groove bottom may be parallel to the major surface or may be inclined relative to the major surface, such that the remaining portion of the parent substrate in the edge region is chamfered, e.g., chamfered with or without radiusing.

[0058] Forming the groove may involve a spiral cut, or a series of round cuts at various diameters using a conventional dicing tool, such as a dicing blade for round cuts, and the material between the inner groove sidewall and the lateral outer surface may be completely removed.

[0059] According to another embodiment, the edge chamfering tool can remove material between the inner groove sidewall and the lateral outer surface (e.g., completely or at least 90% of the material). The edge chamfering tool can be a grinding tool, and the shape of the recess in the grinding pad can be complementary to the vertical cross-sectional shape of the groove. The recess can be formed such that the device substrate is formed with a chamfer along the lateral outer surface and / or such that the reclaimed substrate is formed with a chamfer along the lateral outer surface.

[0060] According to one embodiment, forming the grooves may include laser assisted material removal. Laser assisted material removal may include directing a laser beam towards and / or at the first major surface. In additional or alternative embodiments, laser assisted material removal may include directing a laser beam towards and / or at the second major surface. In the latter case, the parent substrate may be attached front side down to the auxiliary carrier.

[0061] In further additional or alternative embodiments, the laser assisted material removal may include directing a laser beam towards and / or at the first major surface, in which case the parent substrate may be attached with the side opposite the front side down to the auxiliary carrier.

[0062] In general, laser-assisted material removal may involve weakening and / or removing material of a parent substrate by a laser beam. Laser-assisted material removal may include or be at least one of laser-assisted ablation (e.g., laser dicing) or a laser-assisted etch process. Laser-assisted ablation typically utilizes material removal by melting and / or vaporizing and / or sublimating material with a laser beam. Laser-assisted etch processes may involve weakening and / or transforming material of the parent substrate in areas where grooves are to be formed. The weakened material may then be removed, for example, by etching.

[0063] In general, the laser beam may be directed in a direction towards the lateral centre of the parent substrate. For example, the laser beam may be tilted with respect to the horizontal direction or with respect to both the vertical and horizontal directions. The angle between the vertical direction and the propagation axis of the laser beam may be at least 30 degrees. In other embodiments, the angle between the vertical direction and the propagation axis of the laser beam may be at most 10 degrees, for example at most 5 degrees, or 0 degrees. The laser beam may be an ultraviolet laser beam having a peak wavelength of at least 200 nm and at most 450 nm. In other embodiments, the laser beam may be a visible laser beam or an infrared laser beam having a wavelength of, for example, at least 1 μm and at most 1.8 μm. Longer wavelengths may also be possible.

[0064] The laser assisted material removal may be controlled to form a trench having curved inner trench sidewalls. The inner trench sidewalls may be curved inwardly relative to the trench. The ablation volume of the laser assisted material removal may be small compared to the ablation volume of a process that forms the trench with a mechanical dicing tool.

[0065] In some embodiments, the splitting process may form a device substrate having an essentially outwardly curved lateral outer surface that may initially be less susceptible to edge chipping. The splitting process may form a reclaimed substrate having a reinforcing ring whose sidewalls may preferably be shallow and / or curved. In other words, the reinforcing ring may not include steep sidewalls and / or rectangular outer edges, such that the reinforcing ring may initially be less susceptible to edge chipping. The reinforcing ring may facilitate high-yield rework and / or reuse of the thin reclaimed substrate.

[0066] In some embodiments, the splitting process may form a reclaimed substrate having an essentially outwardly curved lateral outer surface that is initially less susceptible to edge chipping. The device substrate may be formed with a stiffening ring whose sidewalls may be preferably shallow and / or curved. In other words, the stiffening ring does not include steep sidewalls and / or rectangular outer edges, such that the stiffening ring is initially less susceptible to edge chipping. The stiffening ring may facilitate further processing with high yields of very thin device substrates obtained from the device substrate.

[0067] The removal and handling stability can be greatly improved for both the device substrate and the reclaimed substrate. By forming the groove from the second major surface, good progress can be made without removing any adhesive material or with only the small amount of adhesive material used to temporarily mechanically connect the parent substrate to the auxiliary carrier.

[0068] According to one embodiment, the method comprises connecting an auxiliary carrier and a mother substrate. A first major surface of the mother substrate is directed towards the processing surface of the auxiliary carrier. In other words, the first major surface of the mother substrate faces the processing surface of the auxiliary carrier. The auxiliary carrier and the mother substrate may be mechanically connected after forming the grooves in the first major surface and / or before forming the grooves in the second major surface. By forming the grooves and splitting the mother substrate, the auxiliary carrier may not be affected at all. The auxiliary carrier may be reworked and reused with little or moderate effort.

[0069] The auxiliary layer and the mother substrate may be directly bonded, or a bonding layer with high thermal stability may bond the first major surface of the mother substrate and the working surface of the auxiliary carrier.

[0070] According to an embodiment, connecting the auxiliary carrier and the mother substrate may include forming an adhesive structure between the working surface of the auxiliary carrier and the central region of the mother substrate. For example, an adhesive material may be deposited on at least one of the working surface of the auxiliary carrier or the first major surface of the mother substrate. The adhesive material may be deposited on the central region of the mother substrate and / or on a central portion of the working surface, which corresponds in size and shape to the central region of the mother substrate. It may be that the adhesive material is not applied to the edge regions. For example, the adhesive material may be deposited in a patterned deposition process, or the adhesive material may be only temporarily deposited on the edge regions of the mother substrate and subsequently removed from the edge regions.

[0071] In particular, the groove may be completely or largely free of adhesive due to the splitting process, which may leave the adhesive unaffected and it is possible that no residue of adhesive material is set free by the splitting process.

[0072] According to an embodiment, connecting the auxiliary carrier and the mother substrate may include forming an adhesive layer between the working surface of the auxiliary carrier and the first main surface of the mother substrate. For example, the adhesive layer may be formed over the entire first main surface. Before splitting, edge portions of the adhesive layer may be selectively released and / or removed relative to a central portion of the adhesive layer in a central region. An auxiliary radiation beam only effective in the edge region may locally generate heat under the peripheral adhesive portion extending outwardly from the outer groove sidewall, releasing the peripheral adhesive portion. According to another embodiment, adhesion may be released in the edge region, for example in the entire edge region and / or including the groove. After removal and / or release of the peripheral adhesive portion, the adhesive material may not block the penetration of cracks into the release layer in the splitting process.

[0073] According to an embodiment, a method of manufacturing a semiconductor device may include providing a device substrate, e.g., a crystalline device substrate, from a mother substrate according to a method as described above. The mother substrate may comprise a semiconductor material. The mother substrate may be a chamfered semiconductor wafer. A semiconductor device may be formed from a portion of the device substrate. Thin semiconductor devices may be formed with little loss of expensive semiconductor material.

[0074] According to one embodiment, the parent substrate may include a central region and an edge region. The edge region may surround the central region. The parent substrate may be any of the parent substrates as described above. By way of example, the parent substrate may include or consist of a crystalline semiconductor material.

[0075] In a central region of the parent substrate, a release layer may extend parallel to the major surfaces. The release layer may comprise a modified substrate material. The release layer may be any of the release layers described above.

[0076] In the edge region of the parent substrate, the groove may laterally surround and / or encircle the central region. The groove, e.g., the major axis of the groove, may extend perpendicularly and / or at an angle to the release layer. The groove may be any of the grooves as described above or below. For example, the groove may have been formed in a manner as described above or below. The release layer may terminate at the groove. For example, the release layer may terminate at an inner groove sidewall of the groove.

[0077] According to one embodiment, the distance between the major surfaces of the parent substrate may decrease with increasing distance to the lateral centre of the parent substrate.

[0078] According to one embodiment, the groove may include an inner groove sidewall. The inner groove sidewall may include a vertical sidewall segment. The release layer may cut the vertical sidewall segment. The groove may be spaced apart from an outer edge of the parent substrate. Alternatively, the groove may extend inwardly from a lateral outer surface of the parent substrate.

[0079] According to one embodiment, the inner groove sidewalls may be curved inwardly relative to the groove. Correspondingly, the portion of the first substrate between the release layer and the first major surface may be curved outwardly. The groove may extend from the first major surface or from the second major surface of the parent substrate into the parent substrate.

[0080] For example, the groove may form a complete circle in a horizontal plane. The diameter of the circle may be smaller than the maximum inscribed circle of the horizontal shape of the parent substrate, and the parent substrate may have one or more flats along its periphery. The groove may be vertical or inclined towards the center of the circle, and the angle between the major axis of the groove and the horizontal plane may range from 15 degrees to 45 degrees. The groove may be formed exclusively in a portion of the parent substrate whose major surfaces extend parallel to each other. Alternatively, the groove may be formed partially or completely in a portion where the distance between the front side and the opposite side decreases, for example in a portion where the parent substrate exhibits chamfering and / or rounding. For example, the groove may be formed completely or partially in a chamfered and / or rounded portion along an edge of the parent substrate.

[0081] According to other embodiments, the groove may include one or more straight portions and one or more circular arcs, which are complementary to each other to form a closed shape. The diameter of the circular arcs may be smaller, equal to or larger than the maximum inscribed circle of the horizontal shape of the parent substrate, which shape may include one or more flats along the periphery. Each of the straight portions of the groove may extend parallel to one of the flats. The groove may be vertical or inclined towards the center of the circle, and the angle between the major axis of the groove and the horizontal plane may be in the range of 15 degrees to 45 degrees. The groove may be exclusively formed in a part of the edge region, whose major surfaces extend parallel to each other. Alternatively, the groove may be partially or completely formed in a chamfered and / or rounded region of the parent substrate. For example, the groove may be entirely or partially formed in the lateral outer surface.

[0082] According to one embodiment, the wafer composite may include a mother substrate as described above and an auxiliary carrier. The auxiliary carrier may be attached to the mother substrate, with a first major surface of the mother substrate facing the processing surface of the auxiliary carrier. In other words, the first major surface faces the processing surface.

[0083] According to an embodiment, the wafer composite may include an adhesive structure between the auxiliary carrier and the central region of the parent substrate. An adhesive structure may not be present between the auxiliary carrier and the edge region of the parent substrate.

[0084] According to a further embodiment, the processing apparatus may include a profile sensor unit and a laser scanning unit. The profile sensor unit may obtain shape information regarding the parent substrate. For example, the profile sensor unit may obtain information regarding a horizontal shape of the parent substrate. In particular, the profile sensor unit may obtain information regarding a position and / or a dimension of a notch or flat along a circumference of the parent substrate, where apart from the notch or flat, the parent substrate may have a circular horizontal shape in the remainder of the substrate.

[0085] The laser scanning unit may direct a laser beam onto the parent substrate. A laser beam axis of the laser beam may be tilted relative to the exposed major surface of the parent substrate. The angle between the exposed major surface and the laser beam axis may be at least 10 degrees and at most 90 degrees. The tilt angle is oriented such that the laser beam is directed toward a lateral center of the parent substrate.

[0086] The location of the laser beam may be close to the outer edge of the parent substrate. For example, the laser beam may irradiate an edge region of the exposed major surface, the edge region being a ring-shaped stripe including the outermost 3 mm of the exposed major surface. Alternatively, the laser beam may irradiate a lateral outer surface of the parent substrate. Alternatively, the location of the laser beam may overlap both the edge region and the lateral surface area.

[0087] The track of the laser beam on the master substrate is controllable as a function of the shape information obtained from the profile sensor unit, in particular the laser beam may follow a notch or a flat detected by the profile sensor unit.

[0088] According to one embodiment, the processing apparatus may include a stage unit adapted to reversibly connect a major surface of a master substrate. The stage unit may be movable relative to the laser beam and / or the laser beam may be movable relative to the stage unit such that the laser beam may follow a track along the circumference of the master substrate. The relative motion between the laser beam and the stage unit may include rotational motion, radial motion, and / or linear motion in two orthogonal directions. The processing apparatus facilitates the formation of any type of groove as described above.

[0089] The method embodiments described herein may be used to manufacture the crystalline substrate embodiments described herein. In at least some embodiments of the methods and / or crystalline substrates, the following features apply (where applicable), either alone or in combination: (i) The release layer terminates at and / or is in direct contact with the groove. (ii) forming the grooves includes laser-assisted material removal, such as a laser-assisted etch process and / or laser ablation (eg, laser dicing); (iii) Laser assisted material removal involves directing a laser beam into the first or second major surface of the parent substrate. (iv) Laser-assisted material removal involves directing a laser beam, fully or partially, into a lateral outer surface of the parent substrate, wherein the angle between the propagation direction of the laser beam and a horizontal plane is at least 20 degrees, such as at least 30 degrees. (v) Laser-assisted material removal involves directing a laser beam, fully or partially, into a lateral outer surface of the parent substrate, the angle between the propagation direction of the laser beam and the horizontal plane being at most 75 degrees, e.g. at most 60 degrees. (vi) The laser beam extends essentially parallel to the vertical direction. (vii) The edge region is defined by and / or corresponds to a chamfered outer region of the parent substrate. (viii) The transition between the groove bottom and the inner groove sidewall may be radiused.

[0090] 1A-1C show an embodiment having a groove 190 formed on the front side of a crystalline parent substrate 100. FIG.

[0091] The parent substrate 100 of FIG. 1A may comprise a ceramic, such as sapphire α-Al2O3, or a semiconductor, such as hexagonal polytype silicon carbide. The parent substrate 100 may be a virgin substrate after being cut from a crystalline boule, or may be a processed substrate, such as a semiconductor wafer. A first major surface 101 on the front side and a second major surface 102 on the back side extend primarily parallel to each other. The second major surface 102 may have the same shape and size as the first major surface 101. The first and second major surfaces 101, 102 may be substantially planar or corrugated. The first major surface 101 and / or the second major surface 102 may be inclined with a tilt from the crystal axis of about 4 degrees relative to the plane of the hexagonal crystal lattice of the parent substrate 100. Lateral outer surfaces 103 connect the edges of the first major surface 101 and the edges of the second major surface 102.

[0092] The parent substrate 100 may include a central region 110 and an edge region 180 between the central region 110 and an outermost edge of the laterally outer surface 103. The central region 110 may include a number of device regions 115. The edge region 180 is free of device regions 115.

[0093] The device regions 115 are arranged in rows and columns. A grid-like kerf region 116 laterally separates the device regions 115 from one another. Each device region 115 may include at least some structures that define an integrated circuit. The integrated circuit may be a power semiconductor device. Each device region 115 may include structures formed on a semiconductive main portion of a parent substrate. For example, a front side metallization may be formed on the semiconductive main portion. The front side metallization may include a first load electrode of a power semiconductor device and, if applicable, a control electrode, e.g., a gate electrode of a MOSFET (metal oxide semiconductor field effect transistor), an IGBT (insulated gate bipolar transistor), or a JFET (junction field effect transistor).

[0094] The grooves 190 are formed in the edge regions 180. The release layer 150 is formed in the central region 110. The release layer 150 may be formed before or after the grooves 190. For example, the release layer 150 may be formed before the grooves 190 to avoid edge effects that may affect the formation of the release layer 150 in areas close to the grooves 190. According to another embodiment, the grooves 190 may be formed before the release layer 150, and the formation of the grooves 190 may be combined with a front side treatment and the formation of the release layer may be combined with a back side process, for example laser treatment from the back side.

[0095] The exfoliation layer 150 shown in FIG. 1B may include modified structures that include the material of the parent substrate in a modified form. The modified structures may include porous materials, implant-induced crystal damage, and / or laser-induced material modifications. The modified stripes are laterally separated by stripes of unmodified material. In addition, the exfoliation layer may include microcracks that run along major crystal planes, e.g., along the a-plane. The microcracks may initiate at the modified stripes and / or pass in close proximity to the modified stripes.

[0096] The first distance d1 between the release layer 150 and the first major surface 101 may be smaller than the first vertical extent v1 of the groove 190. The groove 190 may be formed by a tool suitable for front side processing in the field of manufacturing semiconductor devices. For example, the groove 190 may be formed using an edge trim wheel, a dicing blade, and / or a patterned etch process, such as reactive ion beam etching. Alternatively, the groove may be formed by a dedicated tool designed for forming the groove 190, for example by plasma etching with a vertical or tilted laser beam. The groove 190, for example the major axis 194 of the groove 190, extends parallel to the vertical direction 104.

[0097] A grid-like dicing grid (not illustrated) may be formed in the kerf region 116 before or after forming the grooves 190. The dicing grid may extend from the first major surface 101 into the mother substrate 100. The vertical extent of the dicing grid may be less than the first distance d1 between the first major surface 101 and the exfoliation layer 150.

[0098] In the illustrated example, the grooves 190 extend from the first major surface 101 at the front side into the parent substrate 100. According to another embodiment (not illustrated), the grooves 190 extend from the second major surface 102 at the back side into the parent substrate 100.

[0099] In the illustrated example, the grooves 190 extend vertically into the parent substrate 100. According to other embodiments (not illustrated), the grooves 190 are inclined towards the lateral centre of the parent substrate 100 at an angle in the range of 5 degrees to 85 degrees with respect to the vertical, and the grooves 190 may extend into the parent substrate 100 from the first major surface 101 or from the second major surface 102.

[0100] In the illustrated example, the grooves 190 extend from horizontal surface sections into the parent substrate 100. According to other embodiments (not illustrated), the grooves 190 extend partially or completely into the parent substrate 100 from non-horizontal surface sections of the first major surface or from non-horizontal surface sections of the second major surface 102, and the grooves 190 may be vertical or inclined towards the lateral centre of the parent substrate 100 at an angle in the range of 5 degrees to 85 degrees with respect to the vertical. The non-horizontal surface sections may be chamfered and / or rounded surface portions.

[0101] The splitting process may split the crystalline parent substrate 100 along a pleated splitting plane 155. The splitting plane 155 is formed inside the release layer 150. If the release layer 150 is based on laser-induced modification of the material of the parent substrate 100, the splitting process may include application of a volumetric lattice stress. The volumetric lattice stress may be applied via ultrasound or by generating a thermomechanical stress. For example, a polymer foil may be attached to the first major surface 101 or to the second major surface 102. The parent substrate 100 and the polymer foil may be cooled to a temperature below the glass transition temperature of the polymer foil. The polymer foil contracts to induce a volumetric lattice stress in the parent substrate 100. The mechanical stress induces the propagation of microscale cracks propagating along the major lattice planes, e.g., the a-planes, and existing microcracks merge into the pleated splitting plane 155 that extends mainly laterally through the release layer 150. The creation of the splitting plane 155 begins at the exposed edge of the release layer 150 within the groove 190. The steep sidewalls of the groove 190, which may not be filled with a solid material but may be filled with a fluid, may facilitate a highly reproducible course of the splitting process.

[0102] As shown in Fig. 1C, the parent substrate of Fig. 1B is divided into a first parent substrate portion and a second parent substrate portion. The first parent substrate portion (device substrate 410) includes a portion of the parent substrate 100 between the first major surface 101 of Fig. 1B and the splitting surface 155. The second parent substrate portion (recycled substrate 420) includes a portion of the parent substrate 100 between the splitting surface 155 of Fig. 1B and the second major surface 102 of Fig. 1B.

[0103] Device substrate 410 includes a first substrate portion 415 having a first exfoliation layer portion 416 and a lateral outer surface 413. Reclaimed substrate 420 includes a second substrate portion 425 and a second exfoliation layer portion 426. Reclaimed substrate 420 includes a stiffening ring 427 that projects upwardly from second exfoliation layer portion 426 along the periphery of reclaimed substrate 420.

[0104] 2 shows a schematic plan view of a cylindrical mother substrate 100. By way of example only, the lateral outer surface 103 of the mother substrate 100 includes a flat portion 106. In other embodiments, the lateral outer surface 103 may include a notch portion or may include multiple flat portions. The groove 190 may completely surround the central region 110. The groove 190 may include a circular portion 199 and a linear portion 198. The circular portion 199 may form or approximate a segment of a circle, the center of the circle coinciding with the lateral center 105 of the mother substrate 100. The linear portion 198 may run parallel to the flat portion 106 of the lateral outer surface 103. The circular portion 199 and the line portion 198 may complement each other into a continuous uninterrupted frame.

[0105] Circular portion 199 may form a segment of a circle and may be formed by a point-symmetric process, such as a round cut or edge trim. Alternatively, circular portion 199 may include orthogonal linear sections such that groove 190 follows a stepped line that approximates a segment of a circle, and circular portion 199 may be formed by a process tool using Cartesian coordinates, for example, to generate an etch mask on first major surface 101.

[0106] According to another embodiment (not illustrated), the groove 190 may be circular.

[0107] 3 shows a central region 110 including device regions 115 and a grid-like dicing grid 117 that laterally separates the device regions 115 from one another. The grooves 190 that separate the device regions 115 from the edge regions 180 may include linear portions that are orthogonal to the lateral projections of the line segments of the dicing grid 117. The grooves 190 may have a greater vertical extent than the dicing grid. The grooves 190 may have a greater lateral width than the line segments of the dicing grid 117 and / or may have a different vertical cross-sectional shape than the line segments of the dicing grid 117. According to one embodiment, the grooves 190 may be laterally separated from the dicing grid 117.

[0108] 4A-4E show vertical cross-sections of a groove 190 extending from the first major surface 101 into the parent substrate 100, as well as the expected location of the release layer 150 relative to the groove 190. The parent substrate 100 includes a chamfer 185 between the outer edge of the first major surface 101 and a straight vertical portion at the outermost edge of the laterally outer surface 103. The chamfer 185 forms part of the laterally outer surface 103. The major axis 194 of the groove 190 extends vertically or is tilted relative to the vertical direction 104.

[0109] In Figure 4A, groove 190 extends inwardly from the laterally outer surface 103. Groove 190 has only an inner groove sidewall 191 located toward the laterally center of first major surface 101. The radial extent (width) of groove 190 is equal to the distance from the inner groove sidewall to the outer periphery of the parent substrate. The radial extent of the groove can be at least 90% and at most 110% of the width of the edge region.

[0110] The groove bottom 195 may extend approximately in a plane parallel to the first major surface 101. According to other embodiments, the groove bottom 195 may decline slightly or rise slightly with decreasing distance to the laterally outer surface 103.

[0111] The transition between the groove bottom 195 and the inner groove sidewall 191 may be rounded, and the radius of the radius r1 may be in the range of 0.5 μm to 50 μm, typically in the range of 1 μm to 15 μm, or in the range of 20 μm to 30 μm. This rounded transition between the groove bottom and the inner groove sidewall may be caused by the tool (e.g., dicing tool, trimming tool, and / or grinding tool) used to prepare the groove. Due to mechanical wear of the tool, the groove may not be precisely cut, but rather rounded. The radius caused by the tool may be taken into account when preparing the groove, for example, when defining the width and / or vertical extent of the groove. Between the first major surface 101 and the radius, the inner groove sidewall 191 may include a vertical or near-vertical sidewall section 193. The release layer 150 may cut the inner groove sidewall 191 at the vertical sidewall section 193.

[0112] Figures 4B and 4C relate to a groove 190 having symmetrically formed inner and outer groove sidewalls 191, 192. The width of the groove 190 in a radial direction, relative to the lateral center of the parent substrate, may decrease with increasing distance to the first major surface 101, either stepwise as illustrated in Figure 4B, or continuously as illustrated in Figure 4C. The opening of the groove 190 at the first major surface 101 has a width in the radial direction.

[0113] A portion of the inner groove sidewall 191 between the first major surface 101 and the exfoliation layer 150 defines the lateral outer surface 413 of the device substrate 410 that can be obtained from the parent substrate 100 by splitting along a split plane through the exfoliation layer 150. The stepped or sloping groove sidewall 191 provides an improved etch profile for the device substrate 410. The risk of edge chipping and breakage during detachment can be reduced at least in process steps that handle the device substrate 410 immediately after the splitting process. The sloping and / or stepped inner groove sidewall 191 can facilitate edge rounding of thin and ultra-thin substrate portions. The thin or ultra-thin substrate portions may have a diameter within the range of normal wafer diameters and a thickness of up to 120 μm, for example up to 80 μm, or even up to 60 μm. The outer groove sidewall 192 may define the shape of the inner sidewall of the stiffening ring 427 of the reclaimed substrate 420.

[0114] 4D-4E relate to asymmetric inner and outer groove sidewalls 191, 192. For example, the inner groove sidewall 191 may include a steeper section than the outer groove sidewall 192. In the steep or nearly vertical sidewall section 193, the release layer 150 may cut the inner groove sidewall 191 orthogonally or nearly orthogonally to enhance the reliability of the volume lattice stress induced splitting process. Above and / or below the vertical sidewall section 193, the inner groove sidewall 191 may be slightly rounded or chamfered. The outer groove sidewall 192 may be significantly shallower than the inner groove sidewall 191. The chamfer 185 and the inner groove sidewall 191 define the sidewalls of the stiffening ring 427. The stiffening ring 427 with shallow sidewalls may be robust against chipping and may facilitate reduced handling complexity of the reclaimed substrate 420.

[0115] In FIG. 4E, groove 190 may be formed by plasma etching, which may use an angled laser beam. Groove 190 may taper with increasing distance to first major surface 101. Inner groove sidewall 191 may be curved. The curvature may extend inwardly relative to groove 190 and outwardly relative to device substrate 410. Additionally, outer sidewall 192 may curve outwardly relative to groove 190 and inwardly relative to stiffening ring 427. Release layer 150 may terminate at or near the blind end of tapered groove 190.

[0116] According to another embodiment (not illustrated), grooves 190 extend from second major surface 102 into parent substrate 100, as described with reference to Figures 4A-4E.

[0117] 5A-5G illustrate a method of manufacturing a semiconductor device, for example a vertical silicon carbide power semiconductor device.

[0118] 5A shows a parent substrate 100, which may be a processed chamfered silicon carbide wafer having a standard diameter and having a standard thickness. The parent substrate 100 includes a central region 110 and an edge region 180 surrounding the central region 110. The edge region 180 separates the central region 110 from the laterally outer surface 103. In the edge region 180, the parent substrate 100 includes a chamfer 185. The chamfer may include chamfered flats and / or radiuses, for example, radiuses between adjacent chamfered flats and radiuses between the chamfered flats and the major surfaces 101, 102.

[0119] The central region 110 includes a plurality of device regions 115. The edge regions 180 are free of device regions 115. The device regions 115 are arranged in rows and columns, with a grid-like kerf region 116 laterally separating the device regions 115 from one another. In each device region 115, several doped regions may be formed. For example, the parent substrate 100 may have a background doping of a first conductivity type, and each device region 115 may include one or more emitter regions 120 of a complementary second conductivity type. The emitter regions 120 may be in contact with the first major surface 101. The emitter regions 120 may be an anode region of a power semiconductor diode or may include a body region of a power switching device including a transistor cell. A front side metallization 171 may be formed on the first major surface 101. The front side metallization 171 may be in contact with the emitter regions 120. A portion of the interlayer dielectric 160 may be formed between a portion of the front side metallization 171 and the first major surface 101. A passivation structure (not illustrated) may cover an edge of the front side metallization 171. A groove 190 may be formed in the edge region 180.

[0120] 5B shows grooves 190 extending from first major surface 101 into mother substrate 100. Grooves 190 may be formed in a horizontal major section of first major surface 101 and may have, by way of example, any of the cross-sectional shapes as described with reference to FIGS. 4A-4E. In addition, a grid-like dicing grid (not illustrated) may be formed in kerf region 116, and the vertical extent of the dicing grid may be smaller than the vertical extent of grooves 190.

[0121] The auxiliary carrier 300 may be attached to the front side of the parent substrate 100. For example, an adhesive layer 200 may adhesively bond the auxiliary carrier 300 onto the first major surface 101 having the front side metallization 171. The adhesive layer 200 may be formed from a temporary bond / peel adhesive. For example, a liquid glue may be applied onto the front side of the parent substrate 100. The glue may at least partially fill the grooves 190 and the gaps between adjacent portions of the front side metallization 171. A pre-bake may dry the glue and / or remove some of the solvent contained in the glue. The auxiliary carrier 300 may be brought into contact with the exposed top surface of the dried glue. The dried glue may be cured by irradiation, for example with ultraviolet radiation, to form the adhesive layer 200.

[0122] A laser beam 800 may be directed at the exposed second major surface 102 of the parent substrate 100 to form a release layer 150 in the central region 110 as shown in FIG. 5A.

[0123] 5C shows a wafer composite 890 including a mother substrate 100 adhesively bonded on its front side to a working surface 301 of an auxiliary carrier 300. The auxiliary carrier 300 may be a glass plate, a sapphire plate, or may include a plate from the material of the main part of the mother substrate 100. For example, the auxiliary carrier 300 may include polycrystalline or crystalline silicon carbide. The adhesive layer 200 may fill the spaces between adjacent portions of the front side metallization 171. The adhesive layer 200 may fill the grooves 190 and may form a meniscus extending from the chamfer 185 of the mother substrate 100 to the working surface 301 of the auxiliary carrier 300.

[0124] The laser beam 800 penetrates through the second major surface 102 at the backside of the parent substrate 100 and forms modified structures 151 in the exfoliation layer 150. The modified structures 151 may include different phases of the semiconductor material of the parent substrate 100, such as elemental silicon, and elemental carbon, such as amorphous carbon. The modified structures 151 may form modified stripes that extend perpendicular to the cross-sectional plane. In addition, the exfoliation layer 150 may include microcracks 154 that are generated by mechanical stresses induced by thermal heating by the laser beam 800 and / or volume expansion due to phase change of the semiconductor material. The exfoliation layer 150 cuts the inner groove sidewalls 191. In other words, the microcracks 154 in the exfoliation layer 150 may terminate at the inner groove sidewalls 191.

[0125] 5A-5C, the grooves 190 are formed on the front side of the mother substrate 100 before the mother substrate 100 is attached front side down to the auxiliary carrier 300. According to another embodiment (not illustrated), the grooves 190 are formed on the back side of the mother substrate 100 after the mother substrate 100 is attached front side down to the auxiliary carrier 300.

[0126] Before or after forming the release layer 150, an auxiliary radiation beam 810 may be directed to the peripheral adhesive portion 280 of the adhesive structure 200, as shown in Figure 5D. For example, the auxiliary radiation beam 810 may be directed to the peripheral adhesive portion 280 exclusively through an auxiliary carrier 300.

[0127] 5E shows a wafer composite 890 including the mother substrate 100 and the auxiliary carrier 300 after removal of the peripheral adhesive portion 280. The central adhesive portion forms an adhesive structure 210 connecting the mother substrate 100 and the auxiliary carrier 300. The groove 190 is free of solid material and may be filled with a fluid, for example, ambient air or a process gas.

[0128] A volume lattice stress induced splitting process is carried out. The volume lattice stress may be induced by application of ultrasound or by attaching a polymer foil to the backside second major surface 102 of the parent substrate 100 and cooling it to a temperature below the glass transition temperature of the polymer foil.

[0129] As shown in Figure 5F, the release layer 150 of Figure 5E is split along the pleated splitting surface 155, terminating at the inner groove sidewall 191. The portion of the first parent substrate between the first major surface 101 and the splitting surface 155 may form a device substrate 410 having a thickness of less than 200 μm, for example less than 100 μm, or less than 50 μm. From the device substrate 410, a thin device substrate may be obtained as described below. The portion of the second parent substrate between the second major surface 102 and the splitting surface 155 forms a reclaimed substrate 420. From the reclaimed substrate 420, a further device substrate may be obtained by a suitable process.

[0130] The corrugated parting surface 155 may be planarized, for example by grinding and / or polishing, for example with a chemical / mechanical polishing process, and / or by heat treatment in a hydrogen-containing atmosphere. The planarization process may include exposing the dicing grid if it is formed according to a DBG approach. Backside processing to complete the vertical power conductor device may be performed. Backside processing may include implanting dopants of at least one conductivity type and forming a backside metallization.

[0131] FIG 5G shows a processed device substrate 450 obtained from the device substrate 410 of FIG 5F. The processed device substrate 450 includes a heavily doped contact region 129 formed along a backside surface 452, and a voltage sustaining layer 121 formed between the contact region 129 and the emitter region 120. The voltage sustaining layer 121 may include a lightly doped drift region and / or a superjunction structure having relatively heavily doped vertically extending p-type and n-type columns. A backside metallization 172 may be formed on the backside surface 452.

[0132] 6A-6C relate to a layer transfer process combined with an epitaxy process, where a transferred layer may be obtained from a semiconductor wafer by a splitting process as described above.

[0133] The grooves 190 are formed in the edge region 180 of the mother substrate 100, for example by edge trimming. The first major surface 101 of the front side of the mother substrate 100 is attached to the auxiliary carrier 300. For example, the first major surface 101 and the working surface 301 of the auxiliary carrier 300 may be directly bonded to each other. According to the illustrated embodiment, a thermally stable bonding layer 250 may be provided between the first major surface 101 of the mother substrate 100 and the working surface 301 of the auxiliary carrier 300. The release layer 150 is formed in the mother substrate 100 as described above.

[0134] 6A shows the release layer 150 terminating at the inner groove sidewall 191. The bonding layer 250 mechanically connecting the auxiliary carrier 300 and the parent substrate 100 may be or include, for example, a silicon nitride layer, a structural layer containing silicon nitride, a layer including highly doped crystalline silicon carbide, and / or polycrystalline silicon carbide. The auxiliary carrier 300 may be made of or include the material of the parent substrate 100. If the parent substrate 100 is a silicon carbide crystal, the auxiliary carrier 300 may also be a silicon carbide crystal, for example a silicon carbide crystal with poor crystal quality.

[0135] The splitting process as described above separates the second mother substrate portion (the reclaimed substrate 420) from the first mother substrate portion (the device substrate 410) along a pleated splitting surface 155 that extends horizontally through the release layer 150 in FIG. 6A.

[0136] As shown in Figure 6B, the fluted parting surface 155 of the device substrate 410 may be polished and / or planarized to some extent and the height of the ribs may be reduced. The device substrate 410 represents a transfer layer suitable as a starting layer for an epitaxy process. An epitaxial layer may be formed on the device substrate 410. Front side processing may form integrated circuit structures in and / or on the epitaxial layer.

[0137] 6C shows a processed device substrate 450, which includes a device substrate 410 and an epitaxial layer 430 obtained by epitaxial growth on the device substrate 410. Emitter regions 120, an interlayer dielectric 160, and a front side metallization 171 may be formed in and / or on the epitaxial layer 430 as described above.

[0138] The processed device substrate 450 may be separated from the auxiliary carrier 300. For example, the bonding layer 250 may be selectively removed, or a further laser-induced separation process on top of the auxiliary carrier 300 may be effected.

[0139] 7A-7B relate to a method of forming the grooves 190 after the mother substrate 100 is mounted on the auxiliary carrier 300. FIG.

[0140] As shown in Figure 7A, the mother substrate 100 may be a mother substrate as described with reference to Figure 5A. The mother substrate 100 may be connected front side down to an auxiliary carrier 300 via an adhesive layer 200. An oblique laser beam 800 may be directed onto the second major surface 102 from the back side.

[0141] The laser beam 800 may be directed vertically onto the second major surface 102 to form a vertical groove extending from the second major surface 102 into the parent substrate 100. The groove 190 may have any of the shapes as described for the grooves extending from the first major surface 101 into the parent substrate 100 with reference to Figures 2 and 4A-4F.

[0142] According to the illustrated embodiment, the propagation axis 801 of the laser beam 800 is tilted by an inclination angle β with respect to the vertical direction 104. The inclination angle β may be in the range of 10 degrees to 80 degrees, for example. The laser beam 800 may induce a plasma etch, and the plasma etch may be controlled to form tapered grooves 190 that terminate at the plane of the release layer 150. Alternatively, the grooves 190 may cut the plane of the release layer 150 and / or may be slightly laterally offset from the release layer 150 by a few micrometers. For example, the vertical extent of the grooves 190 relative to the second major surface 102 may be equal to or greater than the second distance d2 between the second major surface 102 and the release layer 150.

[0143] The shape of inner trench sidewall 191 and outer trench sidewall 192 may be controlled by plasma etch parameters such as energy, angle, and exposure area. For example, inner trench sidewall 191 may curve inwardly relative to groove 190 and outwardly relative to the portion of parent substrate 100 between second major surface 102 and exfoliation layer 150. Correspondingly, outer trench sidewall 192 may be formed to extend inwardly relative to groove 190 and outwardly relative to the portion of the substrate between first major surface 101 and exfoliation layer 150.

[0144] 7A-7B, the grooves 190 are formed on the back side of the mother substrate 100 after the mother substrate 100 is attached front side down to the auxiliary carrier 300. According to another embodiment (not illustrated), the grooves 190 are formed on the front side of the mother substrate 100 before the mother substrate 100 is attached front side down to the auxiliary carrier 300.

[0145] 8A shows a portion of a wafer composite 890 including a mother substrate 100 having a chamfer 185, a groove 190, and a release layer 150 cutting a vertical sidewall section 193 of an inner groove sidewall 191. The chamfer 185 is part of an outer lateral surface 103. An adhesive layer 200 formed between the first major surface 101 of the mother substrate 100 and the working surface 301 of the auxiliary carrier 300 mechanically connects the mother substrate 100 and the auxiliary carrier 300.

[0146] Forming the grooves 190 before attaching the parent substrate 100 to the auxiliary carrier 300 avoids ablation of debris and can be performed with existing tools, e.g., conventional edge trimmers. The edge trimming process can be relatively fast and cheap. Existing tools for edge trimming allow for rapid integration of the process into process lines. The auxiliary carrier 300 remains intact and can be reused without extensive rework.

[0147] 8B shows a grinding pad 850 of a chamfer wheel etch trimmer. The shape of the recesses 851 in the grinding pad 850 may shape the outer lateral surface 103 of the master substrate 100, and a groove 190 is formed on the front side of the master substrate 100. In addition, the grinding pad 850 may shape the chamfers along the outer lateral surfaces of the device substrate 410 and the reclaimed substrate 420. The multiple recesses 851 may reduce process time.

[0148] In FIG. 9A , the groove 190 extends from the first major surface 101 into the parent substrate 100. The groove 190 is formed at a distance from the lateral outer surface 103. Forming the groove 190 may include cutting with a round cut blade. Forming the groove 190 may additionally or alternatively include linear dicing and / or grinding in a portion parallel to the flat portion of the lateral outer surface 103. Alternatively, the groove 190 may be formed by at least one of the following: (i) laser ablation processes or laser assisted etch processes, for example using UV (ultraviolet) laser radiation, (ii) plasma and / or patterned etch processes, for example RIE (reactive ion beam etching), and / or (iii) electrical discharge machining (EDM) and / or electrochemical discharge machining (ECDM).

[0149] According to FIG. 9B, a spiral cut or multiple round cuts at various diameters may form a groove 190 that extends outwardly to the laterally outer surface 103 .

[0150] 10 shows a groove 190 formed by front-side micromachining. The process may use UV ablation using an angled laser beam. The amount of ablation may be relatively small, and both a chamfered device substrate 410 and a reclaimed substrate 420 with a chamfered stiffening ring 427 may be formed.

[0151] 11A-11D relate to an embodiment using backside micromachining. The process may use UV ablation using an inclined laser beam. The process may be performed after mounting the parent substrate 100 to the auxiliary carrier 300. The inclined laser beam 800 may be controlled to form both the chamfered remanufactured substrate 420 and the device substrate 410 together with the chamfered stiffening ring 417. The irradiation location of the ablative laser beam 800 may be selected to provide both the favorably chamfered remanufactured substrate 420 and the favorably shaped stiffening ring 417. Alternatively or additionally, the irradiation location of the ablative laser beam 800 may be selected to completely or substantially avoid ablation of a portion of the adhesive layer.

[0152] Forming the groove 190 may include laser-assisted material removal, which may include directing a laser beam, fully or partially, onto the lateral outer surface 103 of the parent substrate 100, where the inclination angle between the propagation direction of the laser beam and a horizontal plane is at least 20 degrees, for example at least 30 degrees.

[0153] In FIG. 11A, grooves 190 extend from the outermost edge of second major surface 102 toward the lateral ends of release layer 150. In FIG.

[0154] 11B, the tilt angle β between the vertical direction 104 and the laser beam axis 801 of the laser beam 800 is about 30 degrees. The irradiated area is entirely within a strictly horizontal major portion of the second major surface 102.

[0155] In FIG. 11C, the tilt angle β is about 30 degrees, with the illuminated area being primarily within the slightly chamfered portion of the second major surface 102 and to some extent on the lateral outer surface 103.

[0156] 11D, the tilt angle β is about 75 degrees. The irradiated area is entirely on the lateral outer surface 103.

[0157] 11A-11D, the grooves 190 are formed in the backside of the mother substrate 100 after the mother substrate 100 is attached front-side down to the auxiliary carrier 300. According to other embodiments (not illustrated), the grooves 190 are formed similarly to those shown, but are formed in the front side of the mother substrate 100 before the mother substrate 100 is attached front-side down to the auxiliary carrier 300.

[0158] FIG. 12 shows a schematic diagram of a processing apparatus 900 for inclined laser ablation along the circumference of a crystalline parent substrate at an arbitrary horizontal cross section. A profile sensor unit 910 may obtain shape information regarding the shape of the parent substrate 100. A scan unit 930 may generate a laser beam 800 that is irradiated onto the parent substrate at an angle of 10 degrees to 80 degrees with respect to the vertical direction, and may control the position of the irradiation site of the laser beam 800 on the parent substrate. A wafer composite 890 including the parent substrate may be temporarily mounted on a stage unit 940. The stage unit 940 may enable rotation and / or linear movement of the wafer composite 890 relative to the profile sensor unit 910 and the scan unit 930.

[0159] The control unit 920 may process information obtained from the profile sensor unit 910 and, if applicable, from the stage unit 940, and may control the relative movement between the scan unit 930 and the stage unit 940 so that the laser beam 800 follows a desired path on the surface of the wafer complex 890.

[0160] As described with reference to Figures 4A-4E, 10, and 11A-11D, processing apparatus 900 allows for the formation of any of the grooves as described above, and in particular groove 190. [Explanation of symbols]

[0161] 100 Mother Board 101 First major surface 102 Second Major Surface 103 Lateral outer surface 104 vertical direction 105 Horizontal center 106 Flat part 110 Central area 115 Device Area 116 Kerf Area 117 Dicing Grid 120 Emitter Area 121 Voltage Sustaining Layer 129 Contact area 150 peeling layer 151 Modified Structure 154 Microcracks 155 Split plane 160 Interlayer Dielectric 171 Front side metallization 172 Backside Metallization 180 Edge Area 185 Chamfered part 190 Groove 191 Inner groove side wall 192 Outer groove side wall 193 Vertical sidewall section 194 Main shaft 195 Groove bottom 198 Linear part 199 Circular Section 200 adhesive layer 210 Adhesive structure 250 Bonding layer 280 Peripheral adhesive part 300 Auxiliary Carrier 301 Machining surface 410 Device Substrate 413 Lateral outer surface 415 First board part 416 First peeling layer portion 417 Reinforcement Ring 420 Recycled Circuit Board 425 Second board part 426 Second peeling layer part 427 Reinforcement Ring 430 Epitaxial layer 450 Device Substrate 452 Back surface 600 Semiconductor Devices 800 Laser Beam 801 Laser beam axis 805 Laser Beam Axis 810 Auxiliary radiation beam 850 Grinding Pad 851 Recess 890 Wafer Complex 900 Processing equipment 910 Profile Sensor Unit 920 Scan Unit 930 Scan Unit 940 Stage Unit

Claims

1. 1. A method for manufacturing a device substrate, comprising: providing a master substrate (100) comprising a central region (110) and an edge region (180), said edge region (180) surrounding said central region (110); forming a release layer (150) in the central region (110), the release layer (150) extending parallel to major surfaces (101, 102) of the master substrate (100), the release layer (150) comprising a modified substrate material; forming a groove (190) in the edge region (180), the groove (190) laterally surrounding the central region (110), the groove (190) extending perpendicularly and / or at an angle to the release layer (150), and the groove (190) laterally delimiting the release layer (150) such that the release layer (150) terminates before reaching the edge region (180).

2. 10. The method of claim 1, further comprising splitting the mother substrate (100) along a split plane (155) through the release layer (150), a portion of the mother substrate (100) forming the device substrate (410).

3. 3. The method of claim 1 or 2, wherein in the edge region (180), the distance between the major surfaces (101, 102) of the parent substrate (100) decreases with increasing distance to a lateral center (105) of the parent substrate (100).

4. The method of any one of claims 1 to 3, wherein the grooves (190) extend from a first major surface (101) of the mother substrate (100) into the mother substrate (100).

5. The method of any one of claims 1 to 4, wherein the groove (190) has an inner groove sidewall (191) oriented towards a lateral center (105) of the mother substrate (100), the inner groove sidewall (191) having a vertical sidewall section (193), and the release layer (150) cuts the vertical sidewall section (193).

6. The method according to any one of the preceding claims, wherein the groove (190) is spaced apart from a lateral outer surface (103) of the mother substrate (100).

7. The method of any one of claims 1 to 5, wherein the grooves (190) extend inwardly from the laterally outer surface (103).

8. 8. The method of claim 1, wherein forming the grooves (190) comprises laser assisted material removal, the laser assisted material removal comprising directing a laser beam (800) onto a first major surface (101) of the mother substrate (100) and / or onto a second major surface (102) of the mother substrate (100), the second major surface (102) being opposite the first major surface (101).

9. 9. The method according to any one of claims 1 to 8, wherein forming the groove (190) comprises laser-assisted material removal, the laser-assisted material removal comprising, fully or partially, directing a laser beam (800) onto a lateral outer surface (103) of the mother substrate (100), the lateral outer surface (103) connecting the two major surfaces (101, 102), and wherein an angle between a propagation direction of the laser beam (800) and a horizontal plane is at least 30 degrees.

10. 10. The method of claim 8 or 9, wherein the laser beam (800) is tilted and directed towards a lateral centre (105) of the parent substrate (100), and the angle between a vertical direction (104) and the laser beam (800) is at least 30 degrees.

11. The method according to any one of claims 1 to 10, further comprising connecting an auxiliary carrier (300) and the mother substrate (100), a first major surface (101) of the mother substrate (100) facing a processing surface (301) of the auxiliary carrier (300), and the auxiliary carrier (300) and the mother substrate (100) being connected after forming the groove (190) in the first major surface (101) and / or before forming the groove (190) in the second major surface (102).

12. 12. The method of claim 11, wherein connecting the auxiliary carrier (300) and the mother substrate (100) comprises forming an adhesive structure (210) between the processing surface (301) of the auxiliary carrier (300) and the central region (110) of the mother substrate (100).

13. The connecting of the auxiliary carrier (300) and the mother board (100) includes: forming an adhesive layer (200) between the working surface (301) of the auxiliary carrier (300) and the first major surface (101) of the mother substrate (100); The method of claim 11, further comprising releasing and / or removing a peripheral adhesive portion (280) of the adhesive layer (200) in the edge region (180) prior to splitting.

14. 1. A method for manufacturing a semiconductor device, comprising:

14. The method according to claim 1, further comprising: splitting the master substrate (100) along a splitting plane (155) in the exfoliation layer (150) to obtain a device substrate (410) from the master substrate (100), the master substrate (100) comprising a crystalline semiconductor material; forming a semiconductor device (600) from a portion of the device substrate (410).

15. a central region (110) and an edge region (180), said edge region (180) surrounding said central region (110); a release layer (150) in said central region (110), extending parallel to said major surfaces (101, 102), said release layer (150) comprising a modified substrate material; a groove (190) in said edge region (180), said groove (190) laterally surrounding said central region (110) and extending perpendicularly and / or obliquely to said release layer (150), said groove (190) laterally delimiting said release layer (150) such that said release layer (150) terminates before reaching said edge region (180); A mother board (100) comprising:

16. 16. The mother substrate of claim 15, wherein in the edge region (180), the distance between the major surfaces (101, 102) of the mother substrate (100) decreases with increasing distance to a lateral center (105) of the mother substrate (100).

17. 17. The mother substrate of claim 15 or 16, wherein the groove (190) has an inner groove sidewall (191), the inner groove sidewall (191) has a vertical sidewall section (193), and the release layer (150) cuts the vertical sidewall section (193).

18. A mother substrate (100) according to any one of claims 15 to 17, a supplementary carrier (300) attached to the parent substrate (100), the first major surface (101) of the parent substrate (100) facing a processing surface (301) of the supplementary carrier (300).

19. 20. The wafer composite of claim 18, further comprising an adhesive structure (210) between the auxiliary carrier (300) and the central region (110) of the parent substrate (100), the adhesive structure (210) not being present between the auxiliary carrier (300) and the edge region (180) of the parent substrate (100).

Images