Laser-assisted method for segmenting crystalline materials

Abstract

A method for processing a crystalline substrate to form a plurality of patterns of subsurface laser damage facilitates subsequent fracture of the substrate to produce first and second substrate portions of reduced thickness. Multiple sets of parallel lines of the plurality of patterns of subsurface laser damage can be sequentially interspersed with one another, with at least some lines of different sets not crossing one another. Certain embodiments include a plurality of patterns of subsurface laser damage having sets of parallel lines that are not parallel to one another, but each line is within ±5 degrees of a <1120> direction of a hexagonal crystal structure of the material of the substrate. Further methods include forming initial and subsequent patterns of subsurface laser damage centered at different depths within the substrate, with the patterns of laser damage being aligned and having overlapping vertical ranges.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to U.S. Patent Application No. 16 / 274064, filed February 12, 2019; U.S. Provisional Patent Application No. 62 / 803340, filed February 8, 2019; and U.S. Provisional Patent Application No. 62 / 786333, filed December 29, 2018, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] This disclosure relates to methods for processing crystalline materials, and more specifically to laser-assisted methods for separating or removing relatively thin layers of crystalline material from a substrate (such as an ingot or wafer). Background Technology

[0004] Various microelectronics, optoelectronics, and microfabrication applications require thin layers of crystalline material as starting structures for manufacturing a variety of useful systems. Traditional methods for slicing thin layers (e.g., wafers) from large-diameter crystalline ingots of crystalline materials involve the use of wire saws. Wire sawing technology has been applied to various crystalline materials such as silicon, sapphire, and silicon carbide. Wire sawing tools consist of ultrafine steel wires (typically with a diameter of 0.2 mm or less) passing through grooves in one or more guide rollers. Two slicing methods exist: loose-mesh slicing and fixed-mesh slicing. Loose-mesh slicing involves applying a slurry (typically a suspension of the material in oil) to a high-speed running wire, whereby the rolling of the material between the wire and the workpiece results in the cutting of the ingot. Unfortunately, the slurry is considerably affected by the environment. To reduce this effect, wires fixed with diamond-coated materials can be used in fixed-mesh slicing methods, which require only a water-soluble coolant liquid (not the slurry). High-efficiency parallel slicing allows for the production of large numbers of wafers in a single slicing process. Figure 1 illustrates a conventional wire saw cutting tool 1, which includes parallel wire segments 3 extending between rollers 4A-4C and arranged to simultaneously saw a spindle 2 into multiple thin segments (e.g., wafers 8A-8G), each segment having a face substantially parallel to an end face 6 of the spindle 2. During the sawing process, the wire portion 3 supported by rollers 4A-4C can be pressed downward in a downward direction 5 toward a support 7 beneath the spindle 2. If the end face 6 is parallel to the crystallization plane c of the spindle 2, and the wire segment 3 saws through the spindle 2 parallel to the end face 6, then each resulting wafer 8A-8G will have a “coaxial” end face 6' parallel to the crystallization plane c.

[0005] Adjacent wafers (also known as off-cut or "off-axis") with end faces not parallel to the crystal c-plane can also be produced. Adjacent wafers with a 4-degree off-cut (e.g., SiC) are often used as growth substrates for high-quality epitaxial growth of other materials (e.g., AlN and other group III nitrides). Adjacent wafers can be produced by growing an ingot in a direction away from the c-axis (e.g., on an adjacent seed material) and sawing the ingot perpendicular to the ingot sidewalls, or by starting an ingot growth with a coaxial seed material and sawing the ingot at an angle deviating from the perpendicular angle to the ingot sidewalls.

[0006] Wire sawing of semiconductor materials involves various limitations. The kerf loss, based on the width of material removed with each cut, is inherent to wire sawing and represents a significant loss of semiconductor material. Wire sawing applies moderately high stress to the wafer, leading to non-zero bending and warping characteristics. The processing time for a single ingot (or stack) is very long, and events such as wire breakage can increase processing time and cause undesirable material loss. Wafer strength can be reduced by flaking and fracture on the cut surface of the wafer. At the end of the wire sawing process, debris must be removed from the resulting wafer.

[0007] Wire saws, with their high wear resistance (and hardness comparable to diamond and boron nitride), can require significant time and resources, resulting in substantial production costs. SiC substrates enable the fabrication of electronic, radio frequency, and optoelectronic devices with desired power. SiC exists in many different crystal structures known as polymorphs, some of which (e.g., 4H-SiC and 6H-SiC) have a hexagonal crystal structure.

[0008] Figure 2 This is a first perspective view of a hexagonal crystal such as 4H-SiC, showing a crystal plane in a coordinate system, where the c-plane ((0001) plane, corresponding to the

[0001] (vertical) direction of epitaxial crystal growth) is perpendicular to the m-plane ((1 00) plane) and a plane ((11) 0) plane, (1) 00) The plane is perpendicular to [1 00] direction, (11 0) The plane is perpendicular to [11 0] Direction. Figure 3 This is a second perspective view of a hexagonal crystal, showing adjacent plane 9 that is not parallel to the c-plane, where vector 10 (perpendicular to adjacent plane 9) is (slightly) oriented towards

[11] . The tilt angle β of the

[0001] direction is away from the

[0001] direction. Figure 4AThis is a perspective wafer orientation view showing the orientation of adjacent wafer 11A relative to the c-plane ((0001) plane), where vector 10A (perpendicular to wafer surface 9A) is tilted at an angle β in the

[0001] direction. This angle β is equal to the orthogonal tilt (or deflection) β spanning between the (0001) plane and the projection 12A of wafer surface 9A. Figure 4B It is a simplified cross-sectional view of the adjacent wafer 11A stacked on a portion of a mole 14A (e.g., a coaxial mole having an end face 6A parallel to the (0001) plane) that defines the adjacent wafer 11A. Figure 4B The wafer surface 9A of the adjacent wafer 11A is shown to be offset by an angle β relative to the (0001) plane.

[0009] Figure 5 This is a top plan view of an exemplary SiC wafer 25, which includes a top surface 26 (e.g., parallel to the (0001) plane (c-plane) and perpendicular to the

[0001] direction) and is laterally defined by a generally circular edge 27 (having a diameter D), the generally circular edge including the direction perpendicular to (11) 0) Plane and parallel to [11 The main flat portion 28 in the direction of 0 (having a length) L F SiC wafers may include an outer surface that is not aligned with the c-plane (e.g., tilted off-axis relative to the c-plane).

[0010] Due to the difficulties associated with manufacturing and handling SiC, SiC device wafers are relatively expensive compared to wafers made from various other semiconductor materials. The typical kerf loss obtained from wire sawing SiC can be approximately 250 micrometers or more per wafer, which is quite significant considering that the wafer produced by the wire sawing process can be approximately 350 micrometers thick and subsequently thinned (by grinding) to a final thickness of approximately 100 to 180 micrometers (depending on the end application). Cutting wafers thinner than approximately 350 micrometers is impractical due to the challenges of wire sawing and device fabrication.

[0011] To address the limitations associated with wire saw cutting, alternative techniques have been developed for removing thin layers of semiconductor material from bulk crystals. A technique involving the removal of silicon carbide layers from larger crystals is described in Kim et al.'s paper, "4H-SiC wafer slicing by using femtosecond laser double pulses," Optical Materials Express 2450, vol. 7, no. 7 (2017). This technique involves creating a laser-written trajectory by impinging laser pulses onto the silicon carbide to induce subsurface damage, followed by adhering the crystal to a locking jig and applying tension to achieve fracture along the subsurface damage region. Using a laser to weaken specific areas in the material, followed by fracture between these areas, reduces laser scanning time.

[0012] Disco Corporation's U.S. Patent No. 9925619 discloses another separation technique involving the formation of laser-induced subsurface damage. By moving a SiC ingot in a forward path, marking the focal point of the laser, and then moving the ingot in a backward path, marking the focal point of the laser again, a laser-induced subsurface damage line is formed. The formation of laser-induced subsurface damage creates internal cracks extending parallel to the c-plane within the ingot, and ultrasonic vibration is applied to the ingot to induce fracture.

[0013] Disco Corporation's U.S. Patent No. 10,155,323 discloses a similar separation technique involving the formation of laser-induced subsurface damage. A pulsed laser beam is supplied to a SiC ingot to form multiple consecutive modified portions, each with a diameter of 17 micrometers, with an 80% overlap in the feed direction, and the laser focus is indexed. The modified portion formation step and the indexing step are performed alternately to produce a separation layer, wherein cracks adjacent to each other in the indexing direction are connected. Subsequently, ultrasonic vibration is applied to the ingot to induce fracture.

[0014] Siltectra GmbH's U.S. Patent Application Publication No. 2018 / 0126484A1 discloses another technique for removing thin layers of semiconductor material from bulk crystals. Laser radiation is applied to a solid material to create separation regions or multiple partially separated regions, followed by the formation of a polymer receiving layer (e.g., PDMS) and cooling (optionally combined with high-speed rotation) to induce mechanical stress that causes the thin layer of solid material to separate from the remainder of the material along the separation regions.

[0015] Tools for forming laser-induced subsurface damage in semiconductor materials are known in the art and are commercially available from various suppliers such as DiscoCorporation (Tokyo, Japan). Such tools allow laser emission to be focused within a crystalline substrate and enable the laser to move laterally relative to the substrate. A typical laser-induced damage pattern involves forming parallel lines that are laterally spaced from each other at a depth within the crystalline material substrate. Parameters such as focus depth, laser power, and translation speed can be adjusted to impart laser-induced damage, but adjustments to certain factors involve trade-offs. Increasing laser power tends to impart larger subsurface damage, which may increase fracturing susceptibility (e.g., by reducing the stress required to complete the fracture), but larger subsurface damage increases surface irregularities along the surface exposed by the fracture, potentially requiring additional processing to make such surfaces sufficiently smooth for subsequent machining (e.g., for bonding to electronic devices). Reducing the lateral spacing between the subsurface laser-induced damage lines may also increase fracturing susceptibility, but reducing the spacing between the laser-induced damage lines increases the amount of translation passing between the substrate and the laser, thereby reducing tooling yield. Furthermore, the results obtained through laser processing can vary within the substrate, depending on the lateral or radial position at a specific vertical location, and / or on the vertical position of the substrate surface relative to its original growth location as part of the ingot.

[0016] Therefore, the art continues to seek improved laser-assisted methods for separating or removing relatively thin layers of crystalline (e.g., semiconductor) material from a substrate to address problems associated with conventional methods. Summary of the Invention

[0017] This disclosure relates in various aspects to a method for processing a crystalline material substrate to form a plurality of subsurface laser-damaged sites in regions of the crystalline material to facilitate subsequent fracture of the substrate to obtain first and second crystalline material portions. The formation of the subsurface laser damage is distributed across a plurality of non-overlapping regions of the crystalline material. For example, a first set of subsurface laser-damaged sites may be formed in non-overlapping first and second regions of the crystalline material. Subsequently, a second set of subsurface laser-damaged sites may be formed in the same non-overlapping first and second regions of the crystalline material, wherein at least some (or all) of the second set of subsurface laser-damaged sites does not intersect with the portions of the first set of subsurface laser-damaged sites. Other sets of subsurface laser-damaged sites may be distributed in the same non-overlapping first and second regions of the crystalline material until the desired amount of subsurface laser damage is formed. It has been found that by distributing the subsurface laser damage in this manner, the spacing between adjacent subsurface laser-damaged sites can be increased (and if such regions are spaced apart, the spacing between non-overlapping regions can be increased), and less subsurface laser damage may be required to separate the crystalline material, thereby enabling increased laser tool throughput and reduced cut loss.

[0018] In some embodiments, each set of subsurface laser-damaged regions is in the form of multiple parallel lines, and each set of parallel lines in a non-overlapping region of the crystalline material forms a subsurface laser-damaged pattern. In some embodiments, multiple (e.g., first and second, first to third, etc.) substantially parallel lines of multiple (e.g., first and second, first to third, etc.) subsurface laser-damaged patterns are scattered. In some embodiments, at least some of the second plurality of substantially parallel lines do not intersect any of the first plurality of substantially parallel lines. Some embodiments involve forming initial and subsequent subsurface laser-damaged patterns, each comprising multiple substantially parallel lines, in a substrate of a crystalline material containing a hexagonal crystal structure, wherein each line is perpendicular to the <11 Within ±5 degrees of the 0> direction, and among the initial plurality of substantially parallel lines, lines are not parallel to subsequent plurality of substantially parallel lines. A further embodiment involves forming a first plurality of subsurface laser-damaged regions in each of a plurality of regions of the crystalline material, and a second plurality of subsurface laser-damaged regions in each of the plurality of regions of the crystalline material, wherein at least some regions of the first plurality of subsurface laser-damaged regions do not intersect with regions of the second plurality of subsurface laser-damaged regions. Other embodiments involve sequentially forming the first and second plurality of subsurface laser-damaged regions across each of a plurality of regions to form a dispersed subsurface laser-damaged region, wherein at least some regions of the first plurality of subsurface laser-damaged regions do not intersect with regions of the second plurality of subsurface laser-damaged regions. A further embodiment involves forming an initial subsurface laser-damaged pattern substantially centered at an initial depth within the crystalline material of the substrate, and forming a subsequent subsurface laser-damaged pattern substantially centered at a subsequent depth within the substrate, wherein the subsequent depth differs from the initial depth, the subsequent subsurface laser-damaged pattern is substantially aligned with the initial subsurface laser-damaged pattern, and at least a portion of the vertical extent of the initial and subsurface laser-damaged patterns overlaps. Each of the foregoing methods can facilitate subsequent fracture of the crystalline material substrate. Other methods involve processing crystalline material with multiple polishing steps to remove subsurface damage and edge polishing to impart beveled or rounded edge profiles, wherein the order of the polishing steps is selected and / or a protective surface coating is used to reduce the likelihood of imparting further surface damage after edge polishing and to prepare the wafer for chemical mechanical planarization. Furthermore, the material handling apparatus includes a laser processing stage, a fracture stage, multiple coarse polishing stages arranged in parallel downstream of the fracture stage, and at least one fine polishing stage arranged downstream of the multiple coarse polishing stages.

[0019] In one aspect, this disclosure relates to a method for processing crystalline materials, comprising providing laser emission focused within the crystalline material of a substrate, and performing relative lateral movement between the laser and the substrate to form subsurface laser damage having a first subsurface laser damage pattern comprising a first plurality of substantially parallel lines. The method further comprises, after forming the first subsurface laser damage pattern, providing laser emission focused within the crystalline material, and performing relative lateral movement between the laser and the substrate to form subsurface laser damage having a second subsurface laser damage pattern comprising a second plurality of substantially parallel lines. The first subsurface laser damage pattern forms a first plurality of cracks extending laterally outward from the lines of the first plurality of substantially parallel lines within the crystalline material, and the second subsurface laser damage pattern forms a second plurality of cracks extending laterally outward from the lines of the second plurality of substantially parallel lines within the crystalline material. According to this method, the lines of the second plurality of substantially parallel lines intersect with the lines of the first plurality of substantially parallel lines, and at least some of the lines of the second plurality of substantially parallel lines do not intersect any of the lines of the first plurality of substantially parallel lines.

[0020] In some implementations, each of the second plurality of substantially parallel lines does not intersect any of the first plurality of substantially parallel lines.

[0021] In some implementations, each of the second plurality of substantially parallel lines is arranged between different pairs of adjacent lines in the first plurality of substantially parallel lines.

[0022] In some embodiments, the crystalline material comprises a hexagonal crystal structure; and each of the first plurality of substantially parallel lines and each of the second plurality of substantially parallel lines is perpendicular to the hexagonal crystal structure at <11 Within ±5 degrees of the 0> direction and substantially parallel to the surface of the substrate.

[0023] In some implementations, the spacing between at least some of the first plurality of substantially parallel lines is substantially the same as the spacing between at least some of the second plurality of substantially parallel lines.

[0024] In some implementations, each of the second plurality of substantially parallel lines does not intersect any of the first plurality of substantially parallel lines.

[0025] In some embodiments, the method further includes, after forming a first subsurface laser damage pattern and a second subsurface laser damage pattern, providing laser emission focused within the crystalline material, and performing relative lateral movement between the laser and the substrate to form subsurface laser damage having a third subsurface laser damage pattern comprising a third plurality of substantially parallel lines. According to this method, the lines in the third plurality of substantially parallel lines are scattered or interlaced among the lines in the first plurality of substantially parallel lines and the second plurality of substantially parallel lines.

[0026] In some implementations, each of the third plurality of substantially parallel lines is arranged between one of the first plurality of substantially parallel lines and one of the second plurality of substantially parallel lines.

[0027] In some embodiments, the focal depth of the laser emission within the substrate is a distance ranging from about 2 micrometers to about 5 micrometers between at least two of the laser damage patterns on the first, second, and third surfaces.

[0028] In some embodiments, a first subsurface laser damage pattern includes a first plurality of cracks extending laterally outward from lines of a first plurality of substantially parallel lines within the crystalline material; a second subsurface laser damage pattern includes a second plurality of cracks extending laterally outward from lines of a second plurality of substantially parallel lines within the crystalline material, and the second plurality of cracks are not connected to the first plurality of cracks; and a third subsurface laser damage pattern includes a third plurality of cracks extending laterally outward from lines of a third plurality of substantially parallel lines within the crystalline material, wherein at least some of the third plurality of cracks are connected to at least some of the first plurality of cracks and to at least some of the second plurality of cracks.

[0029] In some embodiments, each of the third plurality of substantially parallel lines is arranged between corresponding lines of the first plurality of substantially parallel lines and corresponding lines of the second plurality of substantially parallel lines to form a three-line group, such that the laser damage patterns under the first, second, and third surfaces are combined to form a plurality of three-line groups; and for one or more of the plurality of three-line groups, the three-line groups are separated from at least one adjacent three-line group by an inter-group interval exceeding the interval between any two adjacent lines in the one or more three-line groups.

[0030] In some embodiments, the method further includes, after forming first, second, and third under-surface laser damage patterns, providing laser emission focused within the interior of the crystalline material, and performing relative lateral movement between the laser and the substrate to form under-surface laser damage having a fourth under-surface laser damage pattern comprising a fourth plurality of substantially parallel lines; wherein the lines of the fourth plurality of substantially parallel lines are scattered or intersecting among the lines of the first, second, and third plurality of substantially parallel lines.

[0031] In some embodiments, the crystalline material comprises a hexagonal crystal structure; and each of the first plurality of substantially parallel lines, each of the second plurality of substantially parallel lines, and each of the third plurality of substantially parallel lines deviates from the perpendicularity of the hexagonal crystal structure at an angle ranging from about 1 degree to about 5 degrees. 0> direction, while being basically parallel to the surface of the substrate.

[0032] In some embodiments, the focal depth of laser emission within the substrate is substantially the same during the formation of the first and second subsurface laser damage patterns.

[0033] In some embodiments, at least some of the first plurality of substantially parallel lines are arranged at substantially the same depth within the interior of the crystalline material as at least some of the second plurality of substantially parallel lines.

[0034] In some embodiments, the method further includes: detecting the presence of conditions indicating non-uniform doping of a crystalline material on at least a portion of the surface of a substrate, the non-uniform doping including at least one first doped region and at least one second doped region; and, in response to the detection of conditions indicating non-uniform doping of the crystalline material, changing the laser power during the formation of a first subsurface laser damage pattern and a second subsurface laser damage pattern to provide laser emission at a first average power when forming subsurface laser damage in the first doped region and at a second average power when forming subsurface laser damage in the second doped region.

[0035] In some embodiments, the method further includes repeating a process of at least one of the first, second, or third under-surface laser damage patterns, including providing laser emission focused inside the crystalline material to form a repeating under-surface laser damage pattern aligned with at least one of the first, second, or third under-surface laser damage patterns, wherein the center of the repeating under-surface damage pattern is at a depth relative to the surface of the crystalline material that is different from at least one of the first, second, or third under-surface laser damage patterns.

[0036] In some implementations, the crystalline material includes a single-crystal semiconductor material.

[0037] In some embodiments, the lines in the first plurality of substantially parallel lines are not parallel to the lines in the second plurality of substantially parallel lines, and the angular direction of the lines in the second plurality of substantially parallel lines differs from the angular direction of the lines in the first plurality of substantially parallel lines by no more than 10 degrees.

[0038] In some embodiments, the method further includes breaking crystalline material substantially along or between at least one of a first under-surface laser damage pattern and a second under-surface laser damage pattern to produce first and second crystalline material portions, each having a reduced thickness relative to the substrate but having substantially the same length and width as the substrate.

[0039] In some embodiments, at least one of the first or second crystalline material portions includes a freestanding wafer configured for growing at least one epitaxial layer thereon. In some embodiments, one of the first or second crystalline material portions includes a device wafer including at least one epitaxial layer grown thereon.

[0040] In another aspect, this disclosure relates to a method for processing crystalline materials, comprising: providing laser emission focused within a substrate of the crystalline material, and performing relative lateral movement between the laser and the substrate to form subsurface laser damage having an initial subsurface laser damage pattern comprising an initial plurality of substantially parallel lines; and providing laser emission focused within the substrate, and performing relative lateral movement between the laser and the substrate to form subsurface laser damage having a subsequent subsurface laser damage pattern comprising a subsequent plurality of substantially parallel lines. According to this method, lines among the initial plurality of substantially parallel lines are not parallel to lines among the subsequent plurality of substantially parallel lines; the angular direction of lines among the subsequent plurality of substantially parallel lines differs from the angular direction of lines among the initial plurality of substantially parallel lines by no more than 10 degrees; and at least some lines among the subsequent plurality of substantially parallel lines do not intersect any of the initial plurality of substantially parallel lines.

[0041] In some implementations, each of the subsequent plurality of substantially parallel lines does not intersect any of the initial plurality of substantially parallel lines.

[0042] In some implementations, each of the subsequent plurality of substantially parallel lines is arranged between different pairs of adjacent lines in the initial plurality of substantially parallel lines.

[0043] In some embodiments, the crystalline material comprises a hexagonal crystal structure, wherein each of the initial plurality of substantially parallel lines and each of the subsequent plurality of substantially parallel lines is perpendicular to the hexagonal crystal structure at a distance of <11. Within ±5 degrees of the 0> direction, and substantially parallel to the surface of the substrate.

[0044] In some implementations, the lines in the subsequent plurality of substantially parallel lines are scattered or interspersed among the lines in the initial plurality of substantially parallel lines, and each line in the subsequent plurality of substantially parallel lines is arranged between different pairs of adjacent lines in the initial plurality of substantially parallel lines.

[0045] In some implementations, one or more of the subsequent substantially parallel lines intersect one or more of the initial substantially parallel lines.

[0046] In some embodiments, the initial under-surface laser damage pattern includes a first under-surface laser damage pattern and a second under-surface laser damage pattern, the first under-surface laser damage pattern including a first plurality of substantially parallel lines, the second under-surface laser damage pattern including a second plurality of substantially parallel lines; the subsequent laser damage pattern is embodied as a third under-surface laser damage pattern; and the lines in the third plurality of substantially parallel lines are scattered or intersecting between the lines in the first plurality of substantially parallel lines and the second plurality of substantially parallel lines, each line in the third plurality of substantially parallel lines being arranged between one line in the first plurality of substantially parallel lines and one line in the second plurality of substantially parallel lines.

[0047] In some implementations, each of the first plurality of substantially parallel lines is separated from the nearest line of the second plurality of substantially parallel lines by at least 100 micrometers.

[0048] In some embodiments, the focal depth of the laser emission within the substrate differs by a distance ranging from about 2 micrometers to about 5 micrometers among at least two of the laser damage patterns on the first, second, and third surfaces.

[0049] In some embodiments, a first subsurface laser damage pattern includes a first plurality of cracks extending laterally outward from lines of a first plurality of substantially parallel lines within the crystalline material; a second subsurface laser damage pattern includes a second plurality of cracks extending laterally outward from lines of a second plurality of substantially parallel lines within the crystalline material, and the second plurality of cracks are not connected to the first plurality of cracks; and a third subsurface laser damage pattern includes a third plurality of cracks extending laterally outward from lines of a third plurality of substantially parallel lines within the crystalline material, wherein at least some of the third plurality of cracks are connected to at least some of the first plurality of cracks and to at least some of the second plurality of cracks.

[0050] In some implementations, the focal depth of laser emission within the substrate is substantially the same during the formation of the initial and subsequent subsurface laser damage patterns.

[0051] In some embodiments, the method further includes: detecting the presence of conditions indicating non-uniform doping of a crystalline material on at least a portion of the surface of a substrate, the non-uniform doping including at least one first doped region and at least one second doped region; and, in response to the detection of conditions indicating non-uniform doping of the crystalline material, changing the laser power during the formation of an initial subsurface laser damage pattern and a subsequent subsurface laser damage pattern to provide laser emission at a first average power when forming subsurface laser damage in the first doped region and at a second average power when forming subsurface laser damage in the second doped region.

[0052] In some implementations, the crystalline material includes a single-crystal semiconductor material.

[0053] In some embodiments, the method further includes breaking the crystalline material substantially along at least one of an initial under-surface laser damage pattern and a subsequent under-surface laser damage pattern, or between thereof, to produce first and second crystalline material portions, each having a reduced thickness relative to the substrate but having substantially the same length and width as the substrate.

[0054] In some embodiments, at least one of the first or second crystalline material portions includes a freestanding wafer configured for growing at least one epitaxial layer thereon. In some embodiments, one of the first or second crystalline material portions includes a device wafer including at least one epitaxial layer grown thereon.

[0055] In another aspect, this disclosure relates to a method for processing crystalline materials, comprising: providing laser emission focused at an initial depth within the interior of the crystalline material of a substrate, and performing relative lateral movement between the laser and the substrate to form subsurface laser damage having an initial first subsurface laser damage pattern substantially centered at the initial interior depth; and providing laser emission focused at a subsequent location within the interior of the crystalline material, and performing relative lateral movement between the laser and the substrate to form subsurface laser damage having a subsequent laser damage pattern substantially centered at a subsequent interior depth, wherein the subsequent depth differs from the initial depth, the subsequent subsurface laser damage pattern is substantially aligned with the initial subsurface laser damage pattern, and at least a portion of the vertical extent of the subsurface laser damage of the initial subsurface laser damage pattern overlaps with at least a portion of the vertical extent of the subsurface laser damage of the subsequent subsurface laser damage pattern.

[0056] In some implementations, the difference between the initial depth and the subsequent depth is in the range of about 2 micrometers to about 5 micrometers.

[0057] In some embodiments, the crystalline material comprises a hexagonal crystal structure, and the initial subsurface laser damage pattern comprises an initial plurality of substantially parallel lines; the second subsurface laser damage pattern comprises a subsequent plurality of substantially parallel lines; and each of the initial plurality of substantially parallel lines and each of the subsequent plurality of substantially parallel lines is perpendicular to the hexagonal crystal structure at a distance of <11. Within ±5 degrees of the 0> direction and substantially parallel to the surface of the substrate.

[0058] In some implementations, the lines in the subsequent plurality of substantially parallel lines are non-intersecting relative to the lines in the initial plurality of substantially parallel lines.

[0059] In some implementations, one or more of the subsequent substantially parallel lines intersect one or more of the initial substantially parallel lines.

[0060] In some embodiments, each of the initial under-surface laser damage pattern and the subsequent laser damage pattern includes a first under-surface laser damage pattern and a second under-surface laser damage pattern, the first under-surface laser damage pattern including a first plurality of substantially parallel lines, the second under-surface laser damage pattern including a second plurality of substantially parallel lines; and the lines in the first plurality of substantially parallel lines are not parallel to the lines in the second plurality of substantially parallel lines.

[0061] In some implementations, each of the first plurality of substantially parallel lines is separated from the nearest line of the second plurality of substantially parallel lines by at least 100 micrometers.

[0062] In some embodiments, the method further includes: detecting the presence of conditions indicating non-uniform doping of a crystalline material on at least a portion of the surface of a substrate, the non-uniform doping including at least one first doped region and at least one second doped region; and, in response to the detection of conditions indicating non-uniform doping of the crystalline material, changing the laser power during the formation of an initial subsurface laser damage pattern and a subsequent subsurface laser damage pattern to provide laser emission at a first average power when forming subsurface laser damage in the first doped region and at a second average power when forming subsurface laser damage in the second doped region.

[0063] In some embodiments, the initial under-surface laser damage pattern comprises an initial plurality of substantially parallel lines; the second under-surface laser damage pattern comprises a subsequent plurality of substantially parallel lines; the lines in the initial plurality of substantially parallel lines are not parallel to the lines in the subsequent plurality of substantially parallel lines; and any line in the subsequent plurality of substantially parallel lines is not more than 10 degrees apart from the lines in the initial plurality of substantially parallel lines in orientation.

[0064] In some embodiments, the method further includes breaking the crystalline material substantially along at least one of the initial depth and the subsequent depth or between the initial depth and the subsequent depth to produce first and second crystalline material portions, each having a reduced thickness relative to the substrate but having substantially the same length and width as the substrate.

[0065] In some embodiments, at least one of the first or second crystalline material portions includes a freestanding wafer configured for growing at least one epitaxial layer thereon. In some embodiments, one of the first or second crystalline material portions includes a device wafer including at least one epitaxial layer grown thereon.

[0066] In another aspect, this disclosure relates to a method for processing a crystalline material, the crystalline material comprising a plurality of regions that do not overlap with each other, the method comprising: forming a first plurality of subsurface laser-damaged regions in each of the plurality of regions of the crystalline material; and forming a second plurality of subsurface laser-damaged regions in each of the plurality of regions of the crystalline material, wherein at least some of the first plurality of subsurface laser-damaged regions do not intersect with subsurface laser-damaged regions in the second plurality of subsurface laser-damaged regions. The first plurality of subsurface laser-damaged regions comprise a first plurality of substantially parallel lines, and the second plurality of subsurface laser-damaged regions comprise a second plurality of substantially parallel lines. The method further comprises repeatedly forming at least one of the first plurality of or second plurality of subsurface laser-damaged regions in each of the plurality of regions of the crystalline material, including providing laser emission focused within the interior of the crystalline material to form repeated subsurface laser-damaged regions aligned with at least one of the first plurality of or second plurality of subsurface laser-damaged regions, wherein the repeated subsurface laser-damaged regions are centered at a depth relative to the surface of the crystalline material that is different from at least one of the first plurality of or second plurality of laser-damaged regions.

[0067] In some embodiments, each of the second plurality of substantially parallel lines does not intersect any of the first plurality of substantially parallel lines. In some embodiments, each of the second plurality of substantially parallel lines is arranged between different pairs of adjacent lines in the first plurality of substantially parallel lines.

[0068] In some implementations, the spacing between at least some of the first plurality of substantially parallel lines is substantially the same as the spacing between at least some of the second plurality of substantially parallel lines.

[0069] In some embodiments, the crystalline material comprises a hexagonal crystal structure; and each of the first plurality of substantially parallel lines and each of the second plurality of substantially parallel lines is perpendicular to the hexagonal crystal structure at <112. Within ±5 degrees of the 0> direction and substantially parallel to the flat surface of the crystalline material.

[0070] In some embodiments, the method further includes forming a third plurality of subsurface laser-damaged regions in each of a plurality of regions of the crystalline material after forming a first plurality of subsurface laser-damaged regions and a second subsurface laser-damaged region.

[0071] In some embodiments, the first plurality of subsurface laser-damaged regions include a first plurality of substantially parallel lines; the second plurality of subsurface laser-damaged regions include a second plurality of substantially parallel lines; the third plurality of subsurface laser-damaged regions include a third plurality of substantially parallel lines; and at least some of the third plurality of substantially parallel lines are distributed between the lines of the first plurality of substantially parallel lines and the second plurality of substantially parallel lines.

[0072] In some embodiments, the method further includes repeatedly forming at least one of the first, second, or third subsurface laser-damaged regions to form a repeating subsurface laser-damaged region aligned with at least one of the first, second, or third subsurface laser-damaged patterns, wherein the repeating subsurface laser-damaged region is centered at a depth relative to the surface of the crystalline material that is different from at least one of the first, second, or third subsurface laser-damaged patterns.

[0073] In some implementations, each laser-damaged region extends substantially from one lateral boundary of the crystalline material to another lateral boundary of the crystalline material.

[0074] In some implementations, the plurality of regions includes at least three regions.

[0075] In some implementations, the crystalline material includes a single-crystal semiconductor material.

[0076] In some embodiments, the crystalline material includes a substrate, and the method further includes fracturing the crystalline material substantially along at least one of a first plurality of subsurface laser-damaged regions and a second plurality of subsurface laser-damaged regions or between the first plurality of subsurface laser-damaged regions and the second plurality of subsurface laser-damaged regions to produce first and second crystalline material portions, each of the first and second crystalline material portions having a reduced thickness relative to the substrate, but having substantially the same length and width as the substrate.

[0077] In some embodiments, at least one of the first crystalline material portion or the second crystalline material portion includes a freestanding wafer configured for growing at least one epitaxial layer thereon.

[0078] In some embodiments, one of the first crystalline material portion or the second crystalline material portion includes a device wafer comprising at least one epitaxial layer grown thereon.

[0079] In another aspect, this disclosure relates to a method for processing a crystalline material comprising a plurality of regions that do not overlap with each other. The method includes: sequentially forming first and second plurality of subsurface laser-damaged regions in each of the plurality of regions to form dispersed subsurface laser-damaged regions, wherein at least some of the first plurality of subsurface laser-damaged regions do not intersect with subsurface laser-damaged regions in the second plurality of subsurface laser-damaged regions. The method further includes, after forming the first and second plurality of subsurface laser-damaged regions, forming a third plurality of subsurface laser-damaged regions in each of the plurality of regions of the crystalline material.

[0080] The third plurality of subsurface laser-damaged regions comprise a third plurality of substantially parallel lines, and at least some of these third plurality of substantially parallel lines are interspersed between the lines of the first plurality of substantially parallel lines and the second plurality of substantially parallel lines.

[0081] In some embodiments, the first plurality of subsurface laser-damaged regions include a first plurality of substantially parallel lines, and the second plurality of subsurface laser-damaged regions include a second plurality of substantially parallel lines.

[0082] In some implementations, each of the second plurality of substantially parallel lines does not intersect any of the first plurality of substantially parallel lines.

[0083] In some implementations, each of the second plurality of substantially parallel lines is arranged between different pairs of adjacent lines in the first plurality of substantially parallel lines.

[0084] In some implementations, the spacing between at least some of the first plurality of substantially parallel lines is substantially the same as the spacing between at least some of the second plurality of substantially parallel lines.

[0085] In some embodiments, the crystalline material comprises a hexagonal crystal structure; and each of the first plurality of substantially parallel lines and each of the second plurality of substantially parallel lines is perpendicular to the hexagonal crystal structure at <112. Within ±5 degrees of the 0> direction and substantially parallel to the flat surface of the crystalline material.

[0086] In some embodiments, the method further includes forming a third plurality of subsurface laser-damaged regions in each of a plurality of regions of the crystalline material after forming a first plurality of subsurface laser-damaged regions and a second plurality of subsurface laser-damaged regions.

[0087] In some embodiments, the first plurality of subsurface laser-damaged regions include a first plurality of substantially parallel lines; the second plurality of subsurface laser-damaged regions include a second plurality of substantially parallel lines; the third plurality of subsurface laser-damaged regions include a third plurality of substantially parallel lines; and at least some of the third plurality of substantially parallel lines are distributed between the lines of the first plurality of substantially parallel lines and the second plurality of substantially parallel lines.

[0088] In some embodiments, the method further includes repeatedly forming at least one of the first, second, or third under-surface laser-damaged regions to form a repeating under-surface laser-damaged region aligned with at least one of the first, second, or third under-surface laser-damaged patterns, wherein the repeating under-surface laser-damaged region is centered at a depth relative to the surface of the crystalline material that is different from at least one of the first, second, or third under-surface laser-damaged patterns.

[0089] In some implementations, each laser-damaged region extends substantially from one lateral boundary of the crystalline material to another lateral boundary of the crystalline material.

[0090] In some implementations, the multiple regions include at least three regions.

[0091] In some implementations, the crystalline material includes a single-crystal semiconductor material.

[0092] In some embodiments, the crystalline material includes a substrate, and the method further includes fracturing the crystalline material substantially along at least one of a first plurality of subsurface laser-damaged regions and a second plurality of subsurface laser-damaged regions or between the first plurality of subsurface laser-damaged regions and the second plurality of subsurface laser-damaged regions to produce first and second crystalline material portions, each of the first and second crystalline material portions having a reduced thickness relative to the substrate, but having substantially the same length and width as the substrate.

[0093] In some embodiments, at least one of the first crystalline material portion or the second crystalline material portion includes a freestanding wafer configured for growing at least one epitaxial layer thereon.

[0094] In some embodiments, one of the first crystalline material portion or the second crystalline material portion includes a device wafer comprising at least one epitaxial layer grown thereon.

[0095] In another aspect, this disclosure relates to a method for processing a crystalline material wafer, the crystalline material wafer including a first surface having surface damage thereon, the first surface being defined by an edge, the method comprising: grinding the first surface with at least one first grinding device to remove a first portion of the surface damage; after grinding the first surface with at least one first grinding device, edge grinding the edge to form a beveled or rounded edge profile; and after edge grinding, grinding the first surface with at least one second grinding device to remove a second portion of the surface damage, the second portion being sufficient to make the first surface suitable for further processing by chemical mechanical planarization.

[0096] In some embodiments, the method further includes, after grinding the first surface with at least one second grinding apparatus, performing a chemical mechanical planarization treatment on the first surface to epitaxially grow one or more layers of semiconductor material thereon.

[0097] In some embodiments, at least one first grinding device includes at least one grinding wheel having a grinding surface of less than 5000 grit (e.g., 1000 grit, 1400 grit, 2000 grit, 3000 grit, 4000 grit, etc.), and at least one second grinding device includes at least one grinding wheel having a grinding surface of at least 5000 grit (e.g., 5000 grit, 7000 grit, 8000 grit, 10000 grit, 15000 grit, 20000 grit, 25000 grit, 30000 grit, etc.).

[0098] In some embodiments, grinding the first surface with at least one first grinding device includes removing crystalline material with a thickness of 20 micrometers to 100 micrometers (e.g., 20 micrometers to 80 micrometers, 40 micrometers to 80 micrometers, 40 micrometers to 60 micrometers, etc.), and grinding the second surface with at least one second grinding device includes removing crystalline material with a thickness of 3 micrometers to 15 micrometers (e.g., 5 micrometers to 10 micrometers).

[0099] In some implementations, surface damage includes laser damage and fracture damage.

[0100] In some embodiments, the crystalline material includes silicon carbide, and the first surface includes a Si end face of silicon carbide.

[0101] In another aspect, this disclosure relates to a method for processing a crystalline material wafer, the crystalline material wafer including a first surface having surface damage thereon, the first surface being defined by an edge, the method comprising: grinding the first surface with at least one first grinding device to remove a first portion of the surface damage; after grinding the first surface with at least one first grinding device, grinding the first surface with at least one second grinding device to remove a second portion of the surface damage, the second portion being sufficient to make the first surface suitable for further processing by chemical mechanical planarization; after grinding the first surface with at least one second grinding device, forming a protective coating on the first surface; after depositing a sacrificial material on the first surface, edge grinding the edge to form a beveled or rounded edge profile; and after edge grinding, removing the protective coating from the first surface.

[0102] In some embodiments, the method further includes treating the first surface by chemical mechanical planarization after removing the sacrificial material from the first surface, so as to epitaxially grow one or more layers of semiconductor material on the first surface.

[0103] In some embodiments, at least one first grinding device includes at least one grinding wheel having a grinding surface of less than 5,000 mesh, and at least one second grinding device includes at least one grinding wheel having a grinding surface of at least 5,000 mesh.

[0104] In some embodiments, grinding the first surface with at least one first grinding device includes removing crystalline material with a thickness of 20 micrometers to 100 micrometers, and grinding the second surface with at least one second grinding device includes removing crystalline material with a thickness of 3 micrometers to 15 micrometers.

[0105] In some implementations, the protective coating includes photoresist.

[0106] In some implementations, surface damage includes laser damage and fracture damage.

[0107] In some embodiments, the crystalline material includes silicon carbide, and the first surface includes a Si terminal facet comprising silicon carbide.

[0108] In another aspect, this disclosure relates to a material processing apparatus, comprising: a laser processing stage configured to form a subsurface laser-damaged region in a crystalline material substrate provided to the laser processing stage; a fracture stage arranged to receive the crystalline material substrate processed by the laser processing stage and configured to fracture the crystalline material substrate along the subsurface laser-damaged region to form crystalline material portions removed from the crystalline material substrate, wherein each crystalline material portion includes surface damage; a plurality of coarse grinding stages arranged in parallel downstream of the fracture stage and configured to remove a first portion of the surface damage from the crystalline material portions, wherein at least a first coarse grinding stage and a second coarse grinding stage of the plurality of coarse grinding stages are configured to operate simultaneously to remove the first portion of the surface damage from different crystalline material portions; and at least one fine grinding stage arranged downstream of the plurality of coarse grinding stages and configured to remove a second portion of the surface damage from the crystalline material portions, the second portion being sufficient to make at least one surface of each crystalline material portion suitable for further processing by chemical mechanical planarization.

[0109] In some embodiments, the apparatus further includes at least one chemical mechanical planarization stage arranged downstream of at least one fine grinding stage and configured such that at least one surface of each crystalline material portion is suitable for further processing by chemical mechanical planarization.

[0110] In some embodiments, the apparatus further includes at least one edge grinding table configured to grind the edges of each portion of crystalline material to form a beveled or rounded edge profile.

[0111] In some embodiments, each coarse grinding table includes at least one grinding wheel with a grinding surface of less than 5,000 mesh, and the at least one fine grinding table includes at least one grinding wheel with a grinding surface of at least 5,000 mesh.

[0112] In some embodiments, each coarse grinding stage is configured to remove crystalline material of 20 to 100 micrometers thickness from each crystalline material portion, and each fine grinding stage is configured to remove crystalline material of 3 to 15 micrometers thickness from each crystalline material portion.

[0113] In some embodiments, the laser treatment stage is configured to simultaneously form subsurface laser-damaged zones in multiple crystalline material substrates.

[0114] On the other hand, any of the foregoing aspects, and / or the different separate aspects and features described herein, can be combined for additional advantages. Any of the various features and elements disclosed herein can be combined with one or more other disclosed features and elements, unless indicated to the contrary herein.

[0115] Other aspects, features, and embodiments of this disclosure will become more apparent from the following disclosure and the appended claims. Attached Figure Description

[0116] Several aspects of this disclosure are illustrated in conjunction with the accompanying drawings, which form a part of this specification, and together with the specification serve to explain the principles of this disclosure.

[0117] Figure 1 includes a first frame and a second frame. The first frame provides a perspective view of an ingot received by a conventional wire saw tool and subjected to wire saw cutting, and the second frame provides a perspective view of multiple wafers obtained through the wire saw cutting process.

[0118] Figure 2 This is a first perspective crystal planar view showing a hexagonal crystal such as 4H-SiC in a coordinate system.

[0119] Figure 3 This is a second perspective crystal planar view of a hexagonal crystal, showing adjacent planes that are not parallel to the c-plane.

[0120] Figure 4A This is a wafer orientation perspective view showing the orientation of adjacent wafers relative to the c-plane.

[0121] Figure 4B It is stacked on a part of the ingot Figure 4A A simplified cross-sectional view of the adjacent wafers.

[0122] Figure 5 This is a top view of an exemplary SiC wafer, with superimposed arrows indicating crystal orientation.

[0123] Figure 6A This is a side view of a coaxial ingot of crystalline material.

[0124] Figure 6B yes Figure 6A A side view of an ingot rotated 4 degrees, showing an overlay pattern for cutting the ingot's end.

[0125] Figure 6C This is a side view of the ingot after removing the ends to provide an end face that is not perpendicular to the c-direction.

[0126] Figure 7 This is a schematic perspective view of a movable laser tool configured to focus laser emission within a crystalline material to create subsurface damage.

[0127] Figure 8A and 8B An exemplary laser tool travel path relative to a crystalline material is provided for creating subsurface damage within the crystalline material. Figure 8B Including superimposed arrows, which show the subsurface damage line relative to the hexagonal crystal structure of the crystalline material

[11] 0] Orientation of direction.

[0128] Figure 9 It is a schematic perspective view of the surface structure of off-axis (relative to the c-axis) or adjacent 4H-SiC crystals after fracture but before smoothing. The fractured surface exhibits trapezoidal and step-like features.

[0129] Figure 10A-10D These are schematic diagrams of cross-sections of subsurface laser damage formed in a crystalline material substrate by focusing laser emission onto a bare substrate, through the surface of a substrate supported by a carrier, through a carrier and adhesive layer, and through a carrier into the substrate.

[0130] Figure 11A A top plan view of a crystalline material substrate according to one embodiment is provided, the substrate including dispersed first, second, and third surface-mount laser-damaged patterns defined therein, each damage pattern including patterns perpendicular to

[11] Multiple substantially parallel lines in the direction of 0 (and substantially perpendicular to the flat portion of the main substrate), and laser-damaged patterns are combined to form multiple three-line groups, which are separated from each other by inter-group spacing, which exceeds the spacing between adjacent lines in each three-line group.

[0131] Figure 11B This occurs during the manufacturing process after the laser-damaged pattern is formed on the first surface. Figure 11A A top plan view of the crystalline material substrate shows a plurality of first cracks extending laterally outward from a plurality of substantially parallel lines within the substrate.

[0132] Figure 11C When a laser-damaged pattern is formed under the first surface, a laser-damaged pattern is formed under the second surface. Figure 11B A top plan view of the crystalline material substrate shows a second plurality of cracks extending laterally outward from a second plurality of substantially parallel lines without contacting the first plurality of cracks.

[0133] Figure 11D When a third laser-damaged pattern is formed after the first and second subsurface laser-damaged patterns are formed. Figure 11C A top view of a crystalline material substrate shows a third plurality of cracks within the substrate extending laterally outward from a third plurality of substantially parallel lines and connecting the first plurality of cracks and the second plurality of cracks.

[0134] Figure 12 It is based on something like Figure 11A A top plan view of a crystalline material substrate of one embodiment is shown, which includes dispersed laser-damaged patterns under the defined first to third surfaces, each damage pattern including

[11] relative to the

[11] perpendicular to the substrate surface. [0] Multiple substantially parallel lines deviating by three degrees in direction (and substantially perpendicular to the flat portion of the main substrate), and laser-damaged patterns are combined to form multiple three-line groups, which are separated from each other by inter-group spacing, the spacing being greater than the spacing between adjacent lines in each three-line group.

[0135] Figure 13 This is a top plan view of a crystalline material substrate, which includes scattered first to fourth laser-damaged patterns, wherein all lines are parallel to each other and perpendicular to the

[11] line along the substrate surface. 0] direction (and substantially perpendicular to the flat portion of the main substrate).

[0136] Figure 14 This is a top plan view of a crystalline material substrate according to one embodiment, the substrate including dispersed subsurface laser damage patterns defined therein, wherein the first and second sets of lines are each parallel to each other and perpendicular to

[11] along the surface of the substrate. The direction of the third set of lines (and substantially perpendicular to the flat portion of the main substrate) is such that the third set of lines is not parallel to the first and second sets of lines, but does not intersect with the lines of the first and second sets of lines within the substrate.

[0137] Figure 15 This is a top plan view of a crystalline material substrate according to one embodiment, the substrate including dispersed laser-damaged patterns defined therein, namely first, second, and third surface subsurfaces, wherein the first and second sets of lines are each parallel to each other and perpendicular to

[11] along the surface of the substrate. The direction of the third set of lines (which is substantially perpendicular to the flat portion of the main substrate) is deviated by about 3 degrees, and the third set of lines is perpendicular to the flat portion of the main substrate but does not intersect with the lines of the first and second sets of lines in the substrate.

[0138] Figure 16 This is a top plan view of a crystalline material substrate according to one embodiment, the substrate including dispersed laser damage patterns on defined first, second and third surfaces, wherein all laser damage lines are parallel to each other and the inter-group spacing of the laser damage lines is non-uniform over at least a portion of the substrate.

[0139] Figure 17 It is a top plan view of a crystalline material substrate according to one embodiment, which includes dispersed laser damage patterns under defined first, second and third surfaces, wherein all laser damage lines are parallel to each other and the laser damage lines exhibit variations in intra-group spacing, inter-group spacing and group composition.

[0140] Figure 18It is a top plan view of a crystalline material substrate according to one embodiment, which includes sequentially formed laser damage patterns under the defined first, second and third surfaces, wherein the first and second sets of laser damage lines are parallel to each other, and the third set of laser damage lines are not parallel to the first and second sets of laser damage lines and intersect the first and second sets of laser damage lines.

[0141] Figure 19 It is a top plan view of a crystalline material substrate including laser damage patterns formed sequentially on the first, second and third surfaces, wherein each group of laser damage lines includes parallel lines and each group of laser damage lines is not parallel to the other groups of laser damage lines.

[0142] Figure 20A This is a top view of a crystalline material substrate, showing non-overlapping first, second, and third regions in which laser-damaged areas can be formed.

[0143] Figure 20B After the first plurality of subsurface laser-damaged areas are formed in the first to third regions Figure 20A A top view of the crystalline material substrate.

[0144] Figure 20C After the formation of a second or more subsurface laser-damaged areas in the first to third regions. Figure 20B A top view of the crystalline material substrate.

[0145] Figure 20D After the formation of a third and a third subsurface laser-damaged area in the first to third regions. Figure 20C A top view of the crystalline material substrate.

[0146] Figure 21 This is a top-view plan view of the support frame for a laser processing device, which is arranged to hold four substrates, where one or more lasers can be used to create subsurface laser damage.

[0147] Figure 22A It is a top plan view of a single substrate, which is processed with a split laser beam to simultaneously create subsurface laser damage in two parts of the substrate according to a first subsurface laser damage pattern.

[0148] Figure 22B It is a top plan view of two substrates, which are processed with split laser beams to simultaneously form subsurface laser damage in both substrates according to a first subsurface laser damage pattern.

[0149] Figure 23A It is a schematic cross-sectional view of a crystalline material substrate containing a laser-damaged pattern on a first surface centered at a first depth.

[0150] Figure 23BAfter forming a second under-surface laser damage pattern centered at a second depth and aligned with the first under-surface laser damage pattern, it has an overlapping vertical range of the first and second damage patterns. Figure 23A A schematic diagram of the cross-section of the substrate.

[0151] Figure 24A These are perspective photographs of a SiC wafer after it has been separated from a thermoplastic-bonded sapphire carrier according to the method described herein.

[0152] Figure 24B They separated Figure 24A A perspective view of the sapphire carrier of the SiC wafer.

[0153] Figure 24C yes Figure 24A A partially toned version of a SiC wafer photograph to emphasize the contrast between the central doped ring and the outer ring of the wafer.

[0154] Figure 24D Shown with dashed ellipse annotation Figure 24C The image is used to represent the boundary between the central doped ring and the outer ring of the wafer.

[0155] Figure 25 This is a perspective photograph of the Si junction of a SiC wafer separated from an ingot through a process including forming subsurface laser damage and subsequent separation, with the inset portion (upper right) depicting fragments of the SiC wafer, including the edges depicted in the subsequent scanning electron microscope (SEM) image.

[0156] Figure 26 It was obtained at a 15-degree tilt angle. Figure 25 A 45x magnified SEM image of a portion of a SiC wafer fragment, with superimposed arrows indicating [1] 00] and [11 0] The orientation of the crystal plane.

[0157] Figure 27 It was obtained at a 15-degree inclination angle. Figure 25 A 1300x magnified SEM image of a portion of a SiC wafer fragment.

[0158] Figure 28 It was obtained at a 15-degree inclination angle. Figure 25 A 350x magnified SEM image of a portion of a SiC wafer fragment.

[0159] Figure 29 It was obtained at a 2-degree inclination angle. Figure 25 A 100x magnified SEM image of a portion of a SiC wafer fragment.

[0160] Figure 30It was obtained at a 2-degree inclination angle. Figure 25 A 1000x magnified SEM image of a portion of a SiC wafer fragment.

[0161] Figure 31A yes Figure 25 A confocal laser scanning micrograph of a small central portion of a SiC wafer, showing the location of superimposed crosshairs marking the “grooves” formed by laser scanning.

[0162] Figure 31B yes Figure 31A A partial surface profile of a SiC wafer.

[0163] Figure 32A yes Figure 25 A confocal laser scanning micrograph of the larger top portion of a SiC wafer (as shown in the figure), with superimposed crosshair markings indicating the locations of “grooves” formed by laser scanning.

[0164] Figure 32B yes Figure 32A A surface profile of the portion near the top of a SiC wafer.

[0165] Figure 33A yes Figure 25 A confocal laser scanning micrograph of the larger bottom portion of a SiC wafer (as shown in the figure), with superimposed crosshair markings indicating the location of “grooves” formed by laser scanning.

[0166] Figure 33B yes Figure 33A A surface profile of the portion near the bottom of a SiC wafer.

[0167] Figure 34A It is a schematic side cross-section of a solid carrier having an adhesive material bonded to its surface.

[0168] Figure 34B It includes bonding to crystalline material substrates. Figure 34A A schematic cross-sectional view of a solid carrier and adhesive material assembly, wherein the crystalline material substrate has a laser-damaged area on the surface near the adhesive material flange.

[0169] Figure 34C yes Figure 34B A cross-sectional schematic diagram of the components, wherein the surface of the solid carrier is positioned on a cooling device in the form of a liquid-cooled chuck.

[0170] Figure 34D This is a schematic cross-sectional view of most of the crystalline material substrate separated from a combined assembly (on top of a liquid-cooled chuck) that includes a solid carrier and a portion of the crystalline material removed from the substrate after the crystalline material is fractured along the laser-damaged area below the surface.

[0171] Figure 34E After being removed from the liquid-cooled chuck. Figure 34D A cross-sectional schematic diagram of the combined components, showing residual laser damage on the upward surface.

[0172] Figure 34F This is a schematic cross-sectional view of a crystalline material portion supported by a heated vacuum chuck, wherein the solid carrier and binder material are laterally translated away from the crystalline material portion after the binder material is thermally softened and released.

[0173] Figure 35 It is a schematic cross-sectional view of a crystalline material with subsurface laser damage and bonded to a rigid carrier, wherein the crystalline material and the carrier are arranged in a liquid bath of an ultrasonic generator.

[0174] Figures 36A-36C This is a schematic cross-sectional view illustrating the steps of fracturing crystalline material with subsurface laser damage, including applying a mechanical force near one edge of a carrier to impart a bending moment in at least a portion of the carrier.

[0175] Figure 37A-37O This is a cross-sectional schematic diagram illustrating the steps of a device wafer splitting process, according to which a thick wafer is broken from a crystalline material, at least one epitaxial layer is grown on the thick wafer, and the thick wafer is broken to form first and second bonding assemblies, each bonding assembly including a carrier and a thin wafer separated from the thick wafer, the first bonding assembly including at least one epitaxial layer as part of an operating semiconductor-based device.

[0176] Figure 38 It is a flowchart that schematically illustrates the steps of generating subsurface laser damage and bonding a rigid carrier to a crystalline (e.g., SiC) material ingot, followed by laser separation of the bonded assembly including the carrier and a portion of the crystalline material, further processing of the bonded assembly to form an epitaxial layer on a device wafer, wherein the ingot and rigid carrier return to the process start step.

[0177] Figure 39 yes Figure 38 A schematic cross-sectional view of a portion of a crystalline material substrate, showing subsurface laser damage, with superimposed dashed lines identifying areas of expected cut-loss material attributable to laser damage and subsequent surface treatments (e.g., grinding and planarization).

[0178] Figure 40 This is a schematic diagram of a material processing apparatus according to one embodiment, including a laser processing stage, a material fracture stage, and multiple parallel-arranged rough grinding stages, fine grinding stages, and CMP stages.

[0179] Figure 41 It is based on and Figure 40A schematic diagram of a similar embodiment of a material processing apparatus, but with the edge grinding table arranged between the fine grinding table and the rough grinding table.

[0180] Figure 42 This is a schematic diagram of a material processing apparatus according to one embodiment, including a laser processing stage, a material fracture stage, a plurality of parallelly arranged rough grinding stages, fine grinding stages, a surface coating stage, an edge grinding stage, a coating removal stage, and a CMP stage.

[0181] Figure 43A This is a schematic side cross-sectional view of a first device for holding an ingot according to one embodiment, the ingot having an end face that is not perpendicular to its sidewall.

[0182] Figure 43B This is a schematic side cross-sectional view of a second device for holding an ingot according to one embodiment, the ingot having an end face that is not perpendicular to its sidewall. Detailed Implementation

[0183] This disclosure provides methods for treating a crystalline material substrate to form multiple patterns of subsurface laser damage, said subsurface laser damage promoting subsequent fracture of the substrate to produce a first crystalline material portion and a second crystalline material portion with reduced substrate thickness. Some methods involve multiple successively formed, substantially parallel lines, each distributing a plurality of subsurface laser damage patterns, wherein at least some of the second (e.g., subsequently formed) plurality of lines do not intersect with lines of the first plurality of lines. Some methods involve forming initial and subsequent subsurface laser damage patterns, each pattern comprising multiple substantially parallel lines in a crystalline material substrate, wherein the lines of the initial and subsequent substantially parallel lines are not parallel to each other, wherein the angular direction of the lines of the subsequent substantially parallel lines differs from the angular direction of the lines of the initial substantially parallel lines by no more than 10 degrees, and at least some of the subsequent substantially parallel lines do not intersect with any of the lines of the initial substantially parallel lines. Some methods involve forming an initial subsurface laser damage pattern substantially centered at an initial depth within the crystalline material of a substrate, and forming a subsequent subsurface laser damage pattern substantially centered at a subsequent depth within the substrate (different from the initial depth), wherein the subsequent subsurface laser damage pattern is substantially aligned with the initial subsurface laser damage pattern, and the initial subsurface laser damage pattern and the subsurface laser damage pattern overlap vertically in at least a portion of their respective lengths.

[0184] It is believed that sequentially forming scattered or staggered subsurface laser damage patterns distributed on crystalline materials is beneficial in maintaining sufficient stress within the crystalline material to facilitate subsequent material fracture using the methods described herein, while achieving high laser tool yield and moderate material damage with accompanying low kerf loss. In principle, using high laser power and scanning almost the entire crystalline material to promote fracture along the laser damage lines would be straightforward. This method can reliably separate thin layers of crystalline material from bulk substrates (e.g., ingots), but high laser power tends to increase material damage, thus requiring significant surface treatments (e.g., grinding and planarization) to remove the damage. Close spacing between laser damage lines will help promote fracture, but at the cost of significantly reduced laser processing tool yield. Conventional methods for forming subsurface laser damage involve forming subsurface laser damage lines in the forward direction of the crystalline material, followed by relative indexing in the transverse direction between the material and the laser, then forming subsurface laser damage lines in the backward direction, followed by transverse indexing in the same transverse direction, and so on. This method typically requires higher laser power or closer spacing between sequentially formed laser damage lines, which tends to reduce yield or impart greater damage, thus increasing cut loss due to the need to remove additional material from the laser-treated surface to remove the laser damage. This conventional method does not involve forming a first distribution of subsurface laser damage patterns (e.g., forming a first plurality of laser damage areas on multiple non-overlapping regions of the substrate), and then forming a second distribution of subsurface laser damage patterns (e.g., forming a second plurality of laser damage areas on the same plurality of non-overlapping regions of the substrate), the second subsurface laser damage patterns being interspersed or scattered within the first subsurface laser damage pattern.

[0185] The various embodiments disclosed herein address the problem of facilitating reliable separation of thin layers (e.g., wafers) of crystalline material from a substrate without excessive laser power, while simultaneously achieving high laser tool yield and providing low kerf loss. Some embodiments of this document involve forming an initial distribution of subsurface laser damage patterns in a crystalline material substrate (e.g., on each of a plurality of non-overlapping regions of the substrate), and then forming at least one subsequent distribution of subsurface laser damage patterns in the same substrate (e.g., on each of the same plurality of non-overlapping regions), wherein at least a portion (e.g., lines) of the at least one subsequent laser damage pattern is arranged in the gaps between the laser damage lines of the initial laser damage pattern, thereby providing a scattered or interlaced subsurface laser damage pattern. In some embodiments, at least some (or all) of the laser damage lines of the at least one subsequently formed laser damage pattern do not intersect with the laser damage lines of the initial subsurface laser damage pattern. It is believed that the non-intersection of the laser damage patterns can advantageously avoid localized stress dissipation. In some embodiments, the first and second dispersed subsurface laser damage patterns are formed in a manner that prevents the propagation of localized subsurface cracks between them. However, the application of a third (or subsequent) dispersed subsurface laser damage pattern will cause localized subsurface cracks to propagate and connect in a substantially continuous manner across the entire inner plane of the crystalline material substrate, thereby mitigating subsequent fracture along the laser-damaged region using the techniques disclosed herein. It has been observed that forming dispersed subsurface laser damage according to the methods described herein allows thin layers of crystalline material to be reliably separated from the substrate, with each layer removing a smaller number of laser damage lines, advantageously providing increased laser tool yield while offering a low level of laser damage (achieving low kerf loss).

[0186] The embodiments described below illustrate the necessary information to enable those skilled in the art to practice the embodiments and demonstrate the best mode of practice. When reading the following description in conjunction with the accompanying drawings, those skilled in the art will understand the concepts of this disclosure and recognize the application of these concepts, which are not specifically addressed herein. It should be understood that these concepts and applications fall within the scope of this disclosure and the appended claims.

[0187] It should be understood that although the terms first, second, etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another. For example, without departing from the scope of this disclosure, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0188] It should be understood that when an element, such as a layer, area, or substrate, is referred to as being "on" or extending "onto" another element, it may be directly on or directly extended to the other element, or intermediate elements may be present. Conversely, when an element is referred to as being "directly on" or "directly extended to" another element, no intermediate elements are present. Similarly, it will be understood that when an element, such as a layer, area, or substrate, is referred to as being "above" or extending "above" another element, it may be directly above or directly above the other element, or intermediate elements may be present. Conversely, when an element is referred to as being "directly above" or "directly above" another element, no intermediate elements are present. It will also be understood that when an element is referred to as being connected to or coupled to another element, it may be directly "connected" or "coupled" to the other element, or intermediate elements may be present. Conversely, when an element is referred to as being "directly connected" or "directly coupled" to another element, no intermediate elements are present.

[0189] Relative terms such as “below” or “under” or “upper” or “lower” or “horizontal” or “vertical” may be used herein to describe the relationship between one element, layer, or region and another element, layer, or region as shown in the accompanying drawings. It will be understood that these terms, and those discussed above, are intended to cover different orientations of the device other than those depicted in the accompanying drawings.

[0190] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that, when used herein, the terms “comprises,” “comprising,” “includes,” and / or “including” specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0191] Unless otherwise defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. It will be further understood that terms used herein shall be interpreted as having meaning consistent with their meaning in the context of this specification and the relevant field, and shall not be interpreted in an idealized or overly formal sense unless expressly defined herein.

[0192] As used herein, “substrate” refers to a crystalline material (such as a single-crystal semiconductor material), optionally including an ingot or wafer, said crystalline material being divided into at least two thinner portions having substantially the same lateral dimensions (e.g., diameter or length and width) as the substrate and having sufficient thickness (i) to be surface-treated (e.g., grinding and polishing) to support epitaxial deposition of one or more semiconductor material layers, and optionally (ii) to be independent if and when separated from a rigid carrier. In some embodiments, the substrate may have a generally cylindrical shape and / or may have a thickness of at least about one or more of the following: 300µm, 350µm, 500µm, 750µm, 1mm, 2mm, 3mm, 5mm, 1cm, 2cm, 5cm, 10cm, 20cm, 30cm or greater. In some embodiments, the substrate may include a thicker wafer that is divided into two thinner wafers. In some embodiments, the substrate may be part of a thicker wafer having one or more epitaxial layers disposed thereon (optionally bonded to one or more metal contacts) as part of a device wafer having multiple electrically operated devices. The device wafer may be partitioned according to aspects of this disclosure to produce a thinner device wafer and a second, thinner wafer on which one or more epitaxial layers (optionally bonded to one or more metal contacts) may subsequently be formed. In some embodiments, the substrate may include a diameter of 150 mm or greater or 200 mm or greater. In some embodiments, the substrate may include 4H-SiC having a diameter of 150 mm, 200 mm or greater and a thickness in the range of 100 to 1000 micrometers, or in the range of 100 to 800 micrometers, or in the range of 100 to 600 micrometers, or in the range of 150 to 500 micrometers, or in the range of 150 to 400 micrometers, or in the range of 200 to 500 micrometers, or in any other thickness range or having any other thickness value specified herein.

[0193] Various implementations involve laser-induced subsurface damage, including lines oriented relative to the crystal structure of the substrate. In some implementations, the substrate comprises a crystalline material having a hexagonal crystal structure, wherein the orientation of the laser-induced damage line is perpendicular to the hexagonal crystal structure. 0> direction or <11 perpendicular to the hexagonal crystal structure Within ±5 degrees of the 0> direction, and parallel or substantially parallel to (e.g., within ±5 degrees, ±3 degrees, or ±1 degree) the surface of the substrate. While the main planarization on a conventional 4H-SiC wafer is designed to be parallel to the <11 of the hexagonal crystal structure... 0> orientation, but due to manufacturing variations, the main planar portion may not be truly parallel to this direction. Various SiC wafer manufacturers use parallelism <11 for hexagonal crystal structures. The orientation of the main planar portion within ±5 degrees of the 0> direction provides a publicly available specification. Therefore, it is preferable to use X-ray diffraction (XRD) data rather than wafer planar alignment to determine the appropriate laser orientation for forming subsurface laser damage.

[0194] The methods disclosed herein can be applied to substrates of various crystalline materials, both single-crystal and polycrystalline. In some embodiments, the methods disclosed herein can utilize cubic, hexagonal, and other crystal structures, and may involve crystalline materials with coaxial and off-axis crystal orientations. In some embodiments, the methods disclosed herein can be applied to semiconductor materials and / or wide-bandgap materials. Exemplary materials include, but are not limited to, Si, GaAs, and diamond. In some embodiments, such methods can utilize single-crystal semiconductor materials with hexagonal crystal structures, such as 4H-SiC, 6H-SiC, or group III nitride materials (e.g., GaN, AlN, InN, InGaN, AlGaN, or AlInGaN). The various illustrative embodiments described below generally refer to SiC or specifically to 4H-SiC; however, it should be understood that any suitable crystalline material can be used. Among the various SiC polymorphs, 4H-SiC polymorphs are particularly attractive for power electronic devices due to their high thermal conductivity, wide bandgap, and isotropic electron mobility. Bulk SiC can be grown coaxially (i.e., without intentional angular deviation from its c-plane, suitable for forming undoped or semi-insulating materials) or off-axis (typically deviating from the growth axis (e.g., the c-axis) by a non-zero angle, typically in the range of 0.5 to 10 degrees (or a subrange thereof, such as 2 to 6 degrees or another subrange), potentially suitable for forming N-doped or highly conductive materials). The embodiments disclosed herein can be applied to both coaxial and off-axis crystalline materials, as well as doped and unintentionally doped crystalline semiconductor materials. Doped semiconductor materials (e.g., N-doped SiC) exhibit some infrared absorption, thus requiring higher laser power than undoped materials to impart subsurface laser damage. In some embodiments, the crystalline material may include single-crystal materials and may also include single-crystal semiconductor materials. Some embodiments disclosed herein can utilize coaxial 4H-SiC or adjacent (off-axis) 4H-SiC with cutoff values ​​in the range of 1 to 10 degrees, or 2 to 6 degrees, or about 4 degrees.

[0195] Figure 6A and 6C The diagram schematically illustrates coaxial and off-axis crystalline substrates in ingot form that can be used with the methods disclosed herein. Figure 6A This is a side view of a coaxial ingot 15 of a crystalline material having a first end face 16 and a second end face 17 perpendicular to the c-direction (i.e., the

[0001] direction of a hexagonal crystal structure material such as 4H-SiC). Figure 6B yes Figure 6AA side view of the ingot 15 rotated four degrees, showing an overlay pattern 18 (shown in dashed lines) for cutting and removing the ends of the ingot 15 near the end faces 16, 17. Figure 6C It is by Figure 6B A side view of the off-axis ingot 15A formed by ingot 15 after removing the ends to provide new end faces 16A, 17A not perpendicular to the c-direction. If laser emission of a first depth is provided through end face 16 of ingot 15 to form subsurface laser damage, a carrier (not shown) is bonded to end face 16, and ingot 15 breaks along the subsurface laser damage, a coaxial wafer can be formed. Conversely, if laser emission of a first depth is provided through end face 16A of off-axis ingot 15A to form subsurface laser damage, a carrier (not shown) is bonded to end face 16A, and ingot 15A breaks along the subsurface laser damage, an off-axis wafer can be formed.

[0196] Subsurface laser damage formation

[0197] Tools for forming laser-induced subsurface damage in crystalline materials are known in the art and are commercially available from various suppliers such as Disco Corporation (Tokyo Japan). Such tools allow laser emission to be focused within the interior of a crystalline material substrate and enable the laser to move laterally relative to the substrate. Typical laser damage patterns in the art involve forming parallel lines that are laterally spaced from each other at a depth within the crystalline substrate. Parameters such as depth of focus, laser power, translation speed, and spacing of the subsurface damage lines can be adjusted to impart laser damage; however, adjusting certain factors involves trade-offs. Increasing laser power tends to impart larger subsurface damage, which may enhance fracturing susceptibility (e.g., by reducing the stress required to complete fracture), but larger subsurface damage increases surface irregularities along the surface exposed by the fracture, potentially requiring additional processing to make such surfaces sufficiently smooth for subsequent processing (e.g., for bonding to electronic devices), and this additional processing results in additional cut losses. Reducing the lateral spacing between the subsurface laser damage lines may also enhance fracturing susceptibility, but reducing the spacing between the laser damage lines increases the amount of translational passage between the substrate and the laser, thereby reducing tooling yield.

[0198] Figure 7This is a perspective view of an example of a laser tool 29 configured to focus a laser emission within a crystalline material 30 to form subsurface damage 40. The crystalline material 30 includes an upper surface 32 and an opposing lower surface 34, and the subsurface damage 40 is formed within the crystalline material 30, located between the upper surface 32 and the lower surface 34. The laser emission 36 is focused by a lens assembly 35 to produce a focused beam 38, with its focal point within the crystalline material 30. Such a laser emission 36 can pulsate at any suitable frequency (typically in the nanosecond, picosecond, or femtosecond range) and beam intensity, with a wavelength below the bandgap of the crystalline material 30, to allow the laser emission 36 to be focused at a target depth below its surface. At the focal point, the beam size and short pulse width result in an energy density high enough to cause highly localized absorption leading to the formation of subsurface damage. One or more properties of the lens assembly 35 can be modified to tune the focus of the focused beam 38 to a desired depth within the crystalline material 30. Lateral movement (e.g., lateral translation) between the lens assembly 35 and the crystalline material 30 can be achieved to propagate subsurface damage 40 in a desired direction, as schematically shown by dashed line 44. This lateral movement can be repeated in various patterns, including those described below.

[0199] Figure 8A and 8B An exemplary laser tool travel path relative to a crystalline material is provided for forming subsurface damage within the crystalline material. In some embodiments, the laser tool portion (e.g., including a lens assembly) may be configured to move while the crystalline material is stationary; in other embodiments, the laser tool portion may remain stationary while the crystalline material moves relative to the tool portion. Figure 8A The diagram illustrates a reverse y-direction linear scan movement 46 suitable for forming a pattern of laterally spaced parallel lines within a first crystalline material 45A to mitigate subsurface damage. Figure 8B A linear scan movement 48 in the y-direction above (and beyond) the entire surface of crystalline material 45B (with a slight advance in the x-direction each time the y-direction is reversed) is shown, sufficient to form parallel under-surface laser damage lines distributed throughout crystalline material 45B. As shown, the laser damage lines are perpendicular to the hexagonal crystal structure of crystalline material 45B along the surface of crystalline material 45B

[11] . [0] direction, and substantially parallel to the surface of crystalline material 45B.

[0200] Covering the entire surface of the crystalline material with a laser line formed along the y-direction, and then advancing unidirectionally in the x-direction after each y-direction reversal, can be referred to as a single-pass laser damage formation process. In some embodiments, the crystalline material can be laser-treated to form subsurface damage in two, three, four, five, six, seven, or eight passes, or any other suitable number of passes. Increasing the number of passes at lower laser power can reduce kerf loss. To achieve a desired balance between material loss and processing speed, it has been found that the desired number of laser subsurface damage formation processes before the fracture step is 2 to 5 or 3 to 4.

[0201] In some implementations, the lateral spacing between adjacent laser-induced damage lines (whether formed in a single or multiple pass) can be 80 to 400 micrometers, 100 to 300 micrometers, or 125 to 250 micrometers. The lateral spacing between adjacent laser-induced damage lines affects the laser processing time, fracturing fragility, and (depending on the c-plane orientation or bias) the effective laser damage depth.

[0202] It has been observed that the formation of subsurface laser damage lines in crystalline materials leads to the formation of small cracks extending outward (e.g., laterally outward) from the laser damage lines within the material. These cracks appear to extend substantially or primarily along the C-plane. The length of such cracks appears to be functionally correlated with the laser power level (which can be calculated as the product of pulse frequency and energy per pulse). For adjacent laser damage lines spaced at a specific distance, it has been observed that increasing the laser power during the formation of such laser damage lines tends to increase the ability of cracks to connect or coalesce between the laser damage lines, which favors promoting fracturing.

[0203] If the crystalline material formed by laser damage includes off-axis (i.e., non-c-plane) orientation (e.g., within the range of 0.5–10 degrees, 1–5 degrees, or another bias), this bias can affect the desired laser damage line spacing.

[0204] SiC substrates may include misaligned surfaces (e.g., off-axis at an angle relative to the c-plane). Off-axis substrates may also be referred to as adjacent substrates. After such a substrate is fractured, the fractured surface may include trapezoidal surfaces and steps (which can subsequently be smoothed by surface treatments such as grinding and polishing). Figure 9This is a schematic perspective view of the surface structure of an off-axis 4H-SiC crystal 50 (with an angle A relative to the c-axis basal plane) after fracture but before smoothing. The fractured surface has a step 52 and a trapezoidal surface 54 relative to the c-axis basal plane 56. For a 4-degree off-axis surface, the step theoretically has a height of approximately 17 micrometers for a plateau width of 250 micrometers. For a 4H-SiC crystal with subsurface laser damage, the 250-micrometer interval between laser lines forms a trapezoidal surface with a width of 250 micrometers. After fracture, the stepped surface is ground smooth, planarized, and polished in preparation for the epitaxial growth of one or more layers thereon.

[0205] When subsurface laser damage is formed in a crystalline material (e.g., SiC), and if the subsurface laser damage line is oriented away from the plane perpendicular to the substrate (i.e. not perpendicular to

[11] ), [0] direction), then this laser damage line extends through multiple steps and trapezoidal surfaces in a manner equivalent to off-axis semiconductor material. For the purposes of the following discussion, the term "off-axis laser under-surface damage line" will be used to refer to a line not perpendicular to

[11] Laser-induced surface damage lines in the 0 direction.

[0206] Providing too large a gap between laser-damaged lines beneath adjacent surfaces inhibits the fracture of crystalline materials. Providing too small a gap between laser-damaged lines beneath adjacent surfaces tends to reduce step height, but increases the number of vertical steps, and increasing the number of vertical steps generally requires a greater separating force to complete the fracture.

[0207] Reducing the spacing between adjacent laser-damaged lines to too small a distance can result in reduced return and significantly increase processing time and cost. SiC decomposition requires a minimum laser energy threshold. If this minimum energy level creates a connecting crack between two laser lines spaced approximately 100 micrometers apart, then reducing the laser line spacing below this threshold may offer little benefit in reducing cut loss.

[0208] The surface roughness of the crystalline material exposed by fracture not only affects subsequent processing such as robotic vacuum but also impacts grinding wheel wear, a major expense. Roughness is influenced by the spacing of subsurface laser damage lines and the orientation of these lines relative to the crystal structure of the semiconductor material. Reducing the gap between subsurface damage lines simply reduces the potential step height. Providing off-axis laser subsurface damage lines tends to break long parallel steps that would otherwise exist in the laser-damaged area, and it also helps mitigate at least some of the effects from the slope or curvature of the C-plane. When the laser line is perpendicular to the plane of the substrate, the cleavage plane parallel to the laser line along the C-plane extends from the plane to the relatively bent end of the wafer by approximately 150 mm. Small deviations in the slope or curvature of the C-plane (common for SiC substrates) can produce significant variations in the fracture surface because they force the plane to jump as the fracture propagates. A disadvantage of providing off-axis laser subsurface damage lines is that such lines typically require increased laser power to form connecting cracks between adjacent laser lines. Therefore, in some embodiments, the combination of forming coaxial under-surface laser damage lines (which are perpendicular to the main flat portion) and off-axis under-surface laser damage lines provides a good balance between avoiding excessive variability of the fracture surface and not requiring excessively increased laser power to form connecting cracks between adjacent laser lines.

[0209] In some embodiments, a laser with a wavelength of 1064 nm can be used to implement the methods disclosed herein, and the inventors have experience with processing 4H-SiC. Although a wide range of pulse frequencies can be used in some embodiments, pulse frequencies of 120 kHz to 150 kHz have been successfully employed. A translational stage speed of 936 mm / s between the laser and the substrate to be treated has been successfully utilized; however, higher or lower translational stage speeds can be used in some embodiments, wherein the laser frequency is appropriately adjusted to maintain the desired laser pulse overlap. The average laser power ranges from 3 W to 8 W for forming subsurface laser damage in doped SiC materials and from 1 W to 4 W for undoped SiC materials. The laser pulse energy can be calculated as power divided by frequency. Laser pulse widths of 3 ns to 4 ns can be used, but other pulse widths can be used in other embodiments. In some embodiments, a laser lens numerical aperture (NA) in the range of 0.3 to 0.8 can be used. For implementations involving SiC treatment, given a refractive index change from air (about 1) to SiC (about 2.6), a significant change in the angle of refraction occurs within the SiC material to be treated, making the laser lens NA and aberration correction important for achieving the desired results.

[0210] One of the main drivers of cut loss is subsurface laser damage beneath the primary fracture zone on the ingot side. Typically, an increase in subsurface laser damage increases cut loss. A potential reason for increased subsurface laser damage is the inability to adequately compensate for the optical properties of the crystalline material. In some embodiments, optical parameter optimization can be performed periodically before forming subsurface laser damage in the substrate (e.g., each time the crystalline material substrate (e.g., an ingot) is supplied to the laser tool). This optimization can utilize variable height adjustment to achieve an initial state where the optimal focus of the laser beam is formed on the upper surface of the crystalline material substrate, and then adjust the aperture and / or correction collar adjustment ring of the laser tool according to the subsequent state corresponding to the desired formation depth of subsurface laser damage in the crystalline material.

[0211] In some embodiments, the crystalline material substrate may exhibit doping that varies in position (e.g., lateral and / or diameter) relative to the main surface (e.g., facet) of the substrate. For example, the growth of doped SiC can lead to the formation of doped ring regions with increased dopant concentration (e.g., Figure 24A , 24C As shown in Figure 24D, this results in higher laser absorption and a slightly altered refractive index, both of which affect the impact depth of the focused laser emission within the substrate. Increasing the laser power when focusing the laser emission into the doped ring region, relative to the power used to direct the focused laser emission into the material outside the doped ring region, can compensate for the different properties of the doped ring region. In some embodiments, the presence of conditions indicating non-uniform doping of the crystalline material on at least a portion of the surface of the substrate can be detected to determine the presence of at least one first doped region and at least one second doped region. (Methods for detecting different doping conditions include, but are not limited to, interferometry, resistivity measurement, absorption or reflectivity measurement, and other techniques known to those skilled in the art). Subsequently, in response to the detection of conditions indicating non-uniform doping of the crystalline material, the laser power can be varied during the formation of the subsurface laser damage pattern to provide laser emission at a first average power when forming subsurface laser damage in the first doped region and at a second average power when forming subsurface laser damage in the second doped region, wherein the first average power level and the second average power level are different from each other.

[0212] In some embodiments, the crystalline material substrate may exhibit a varying level of laser absorption relative to its vertical position within the substrate (e.g., within an ingot), particularly for intentionally doped materials. The laser absorption level may also vary from substrate to substrate (e.g., from ingot to ingot). This variation is thought to be attributable to variations in doping. In some embodiments, a lower average laser power (e.g., 3 W) may be used to form subsurface laser damage in substrate regions distant from the seed crystals, while a higher average laser power (e.g., 5.5 W) may be used to form subsurface laser damage in substrate regions adjacent to the seed crystals.

[0213] In some embodiments, for the initial setting of the correct depth of the laser-induced subsurface damage relative to the surface of the crystalline material substrate, an optical measurement of the laser focusing depth in the semiconductor material can be performed (e.g., taking into account the semiconductor material / air refractive index variation), and the settings for the laser damage (e.g., laser power and / or laser focus) can be adjusted in response to this measurement before scanning the entire surface of the substrate. In some embodiments, the optical measurement of the laser focusing depth can be performed once per ingot, or each time after a portion of the ingot is broken and removed (i.e., before the formation of the subsurface laser damage pattern for each substrate layer removed by subsequent breaking).

[0214] In some embodiments, the semiconductor material processing methods disclosed herein may include some or all of the following items and / or steps. A second carrier wafer may be attached to the bottom side of a crystalline material substrate (e.g., an ingot). Subsequently, the top side of the crystalline material substrate may be ground or polished, such as to provide an average surface roughness R of less than about 5 nanometers. a A surface for transmitting laser energy is prepared. Laser damage can then be applied at one or more desired depths within the crystalline material substrate, wherein the spacing and orientation of the laser damage trajectories depend on the crystal orientation of the crystalline material substrate. A first carrier can be attached to the top side of the crystalline material substrate. An identification code or other information linked to the first carrier relates to the wafer obtained from the crystalline material substrate. Alternatively, laser marking can be applied to the wafer (not the carrier) prior to separation to facilitate traceability of the wafer during and after manufacturing. The crystalline material substrate is then fractured along the subsurface laser damage zone (using one or more methods disclosed herein) to provide a portion of the semiconductor material substrate bonded to the first carrier and the remaining portion of the crystalline material substrate bonded to a second carrier. The removed portion of the semiconductor material substrate and the remaining portion of the semiconductor material substrate are ground smooth and cleaned as needed to remove residual subsurface laser damage. The removed portion of the semiconductor material substrate can be separated from the carrier. The process can then be repeated using the remaining portion of the semiconductor material substrate.

[0215] Although wire saw cutting of SiC wafers typically requires a cut loss of at least about 250 micrometers per wafer, the laser-assisted separation method and carrier-assisted separation method disclosed in this paper and applied to SiC can achieve a cut loss of 80 to 140 micrometers per wafer.

[0216] In some embodiments, laser-induced subsurface damage can be formed in the crystalline material substrate before the substrate is bonded to the rigid carrier. In some embodiments, a rigid carrier transparent to the emission of a laser at a desired wavelength can be bonded to the crystalline material substrate before forming the subsurface laser damage. In this embodiment, the laser emission can optionally penetrate through the rigid carrier and enter the interior of the crystalline material substrate. Figure 10A-10D The images show different carrier-substrate surface laser-formed structures. Figure 10A This is a schematic diagram of laser emission 61 converging through the surface of bare substrate 62 to form subsurface laser damage 63 within substrate 62, thereby allowing a rigid carrier to be fixed to substrate 62 after the subsurface laser damage is formed. Figure 10B This is a schematic diagram of laser emission 61 passing through the surface of substrate 62 and converging to form subsurface laser damage 63 within substrate 62, wherein substrate 62 has previously been bonded to rigid carrier 66 using adhesive material 64. Figure 10C This is a schematic diagram of laser emission 61 aggregating through a rigid carrier 66 and an adhesive 64 to form subsurface laser damage 63 within a substrate 62 previously bonded to the rigid carrier 66. In some embodiments, the surface of the substrate 62 remote from the rigid carrier 66 may include one or more epitaxial layers and / or metallization layers, wherein operational electronics are implemented on the substrate 62 prior to the formation of the subsurface laser damage 63. Figure 10D This is a schematic diagram of laser emission 61 being focused by a rigid carrier 66 onto a substrate 62 (without an adhesive layer) to form subsurface laser damage 63 within the substrate 62 previously bonded (e.g., via anodic bonding or other non-adhesive means) to the rigid carrier 66.

[0217] Dispersed surface laser damage

[0218] In some embodiments, subsurface laser damage can be formed in a crystalline material by sequentially forming a plurality of dispersed laser damage patterns, wherein each subsurface laser damage pattern comprises a plurality of substantially parallel lines. In some embodiments, each subsurface laser damage pattern may extend substantially the entire length (e.g., perpendicular to the substrate plane) and include spaced lines distributed over substantially the entire width of the crystalline material substrate. In some embodiments, the dispersed damage patterns may include first and second, or first to third, or first to fourth subsurface laser damage patterns formed sequentially, each subsurface laser damage pattern comprising a plurality of parallel lines. It is believed that sequentially forming a plurality of subsurface laser damage patterns in a dispersed manner (e.g., forming a first subsurface damage pattern, then forming a second subsurface damage pattern, and then forming any subsequent subsurface damage patterns, with the different lines of each damage pattern distributed in the other damage patterns) preferably forms the same trajectory without dispersion, to promote fracturing of the crystalline material along or adjacent to the subsurface laser damage region. We do not wish to be bound by any particular theory, because the improved fracture results obtained by dispersing subsurface laser damage patterns in crystalline materials suggest that the continuous formation of the dispersed subsurface laser damage patterns can preserve a greater degree of internal stress within the semiconductor material to promote the lateral propagation of cracks originating from different subsurface laser damage lines.

[0219] In some embodiments, a first subsurface laser-damaged pattern in the crystalline material includes a first plurality of parallel lines and a first plurality of cracks within the crystalline material, the first plurality of cracks extending laterally outward (e.g., primarily or substantially along the c-plane) from lines of the first plurality of substantially parallel lines, wherein cracks diverging from each line are not connected to cracks diverging from each adjacent line. In some embodiments, after forming the first subsurface laser-damaged pattern, a second subsurface laser-damaged pattern is formed in the crystalline material including a second plurality of cracks extending laterally outward from lines of the second plurality of substantially parallel lines within the crystalline material, and at least some of the second plurality of cracks are connected to cracks diverging from two adjacent lines of the first plurality of lines (e.g., forming continuous cracks).

[0220] In some embodiments, first, second, and third subsurface laser damage patterns are formed sequentially in a crystalline material, each subsurface laser damage pattern comprising a plurality of parallel lines, and the lines of each subsurface laser damage pattern being distributed among the lines of the other subsurface laser damage patterns. In some embodiments, the first subsurface laser damage pattern comprises a first plurality of cracks extending laterally outward from lines of a first plurality of substantially parallel lines within the crystalline material; the second subsurface laser damage pattern comprises a second plurality of cracks extending laterally outward from lines of a second plurality of substantially parallel lines within the crystalline material, the second plurality of cracks being unconnected to the first plurality of cracks; and the third subsurface laser damage pattern comprises a third plurality of cracks extending laterally outward from lines of a third plurality of substantially parallel lines within the crystalline material. In this embodiment, at least some of the third plurality of cracks are connected to (i) at least some of the first plurality of cracks and (ii) at least some of the second plurality of cracks (e.g., forming continuous cracks). In some embodiments, a fourth under-surface laser damage pattern may be formed after the first to third under-surface laser damage patterns. This fourth under-surface laser damage pattern is used to further connect cracks originating from any two or more of the first, second, or third lines. In some embodiments, three, four, five, or more dispersed under-surface laser damage patterns may be provided.

[0221] In some embodiments, one or more portions of the substrate may include a diffused subsurface laser damage pattern, while other portions of the substrate may include a non-diffuse laser damage pattern. In some embodiments, different diffused subsurface laser damage patterns may be provided on the same substrate. For example, a diffused subsurface laser damage pattern on a single substrate may include five damage lines in a first region, four damage lines in a second region, three damage lines in a third region, two damage lines in a fourth region, one damage line (i.e., no diffused pattern) in a fifth region, zero damage patterns in a sixth region, or any combination of two or three of the foregoing, optionally wherein the aforementioned regions have substantially the same unit area. In some embodiments, a regular (e.g., regularly repeating) pattern of diffused damage lines may be present in at least one region of the substrate, and an irregular (e.g., lacking regularly repeating) pattern of diffused or non-diffuse damage lines may be present in at least one other region of the substrate.

[0222] Figure 11A A top plan view of a crystalline material substrate 70 according to one embodiment is provided, the substrate including dispersed first, second, and third subsurface laser damage patterns defined therein. The first, second, and third subsurface damage patterns each include first, second, and third plurality of parallel lines 71, 72, and 73, respectively, perpendicular to the flat portion 78 of the main substrate (and perpendicular to

[11] ). [0] Direction) extending. The three laser-damaged patterns combine to form multiple three-line groups 74, which are separated from each other by an inter-group spacing 75 exceeding the spacing 76, 77 between adjacent lines in each three-line group 74. For clarity, Figure 11A The crack formed by the first, second, and third plurality of parallel lines 71, 72, and 73 is not shown. In some embodiments, the first plurality of parallel lines 71 are formed in a first process, the second plurality of parallel lines 72 are formed in a second process, and the third plurality of parallel lines 73 are formed in a third process. The third process can be used to connect cracks that initially originate from either the first parallel line 71 or the second parallel line 72.

[0223] Continue to refer to Figure 11A In one embodiment, the first plurality of parallel lines 71 may be formed with a pitch of 500 micrometers (i.e., the spacing between lines), and the second plurality of parallel lines 72 may be formed with a pitch of 500 micrometers and an offset of 250 micrometers relative to the first plurality of parallel lines 71. Subsequently, the third plurality of parallel lines 73 may be formed with a pitch of 500 micrometers and an offset of 125 micrometers relative to the first plurality of parallel lines 71. This arrangement produces a plurality of trifilar groups 74, which are separated from each trifilar group by a gap of 250 micrometers, and adjacent lines within each trifilar group are separated from each other by a gap of 125 micrometers.

[0224] The inventor has discovered that, combined with Figure 11A The order of the three-process laser damage formation process is important. If the process order is changed to form the first, third, and second multiple subsurface laser damage lines sequentially, higher laser power is required to complete the cracks across the 250-micron intergroup spacing 75. This is thought to be due to cracks occurring between the 125-micron intervals in the second process when using the original (first, second, third process) sequential order, where the cracks formed in the third process are large enough to connect the cracks emanating from the second subsurface damage line across the second 125-micron gap 77. When the process order is first, third, second, cracks across the intergroup spacing 75 are not observed unless the laser power is increased, but increased laser power generally increases notch loss. Therefore, according to some embodiments where the process order is first, second, third, it may be desirable that the cracks formed in the first and second processes do not connect with each other, and then the cracks formed in the third process create connected cracks across the 125-micron gaps 76, 77 and the 250-micron intergroup spacing 75.

[0225] In some embodiments, the boundary of each three-wire group 74 can be considered as defining the damage-bearing area of ​​the substrate 70, and the damage-bearing area of ​​each three-wire group 74 is spaced apart from the damage-bearing area of ​​each other three-wire group (i.e., by the inter-group spacing 75). It is worth noting that, as Figure 11DAs shown, cracks formed by subsurface laser damage can propagate across the intergroup spacing 75 between adjacent three-line groups 74.

[0226] Figure 11B-11D It shows Figure 11A Manufacturing of crystalline material substrate 70. Figure 11B The image shows a substrate 70 after the formation of a plurality of under-surface laser damage lines 71 (perpendicular to the plane 78 of the substrate 70) having a pitch (or line spacing) 71B and forming a first under-surface laser damage pattern 71A. Cracks 71C extend laterally outward from the plurality of under-surface laser damage lines 71, but cracks originating from different under-surface laser damage lines 71 do not connect with each other.

[0227] Figure 11B The substrate 70 is shown after forming a second plurality of under-surface laser damage lines 72 (perpendicular to the plane 78 of the substrate 70) having a pitch (or inter-line spacing) 72B and forming a second surface laser damage pattern 72A. Cracks 72C extend laterally outward from the second plurality of under-surface laser damage lines 71, but cracks originating from different under-surface laser damage lines 71 do not connect with each other.

[0228] Figure 11C The substrate 70 is shown after the formation of a third plurality of under-surface laser damage lines 73 (perpendicular to the plane 78 of the substrate 70) having a pitch (or inter-line spacing) 73B and forming a third under-surface laser damage pattern 73A. Cracks 73C extend laterally outward from the third plurality of under-surface laser damage lines 73, and such cracks 73C are sufficient to connect cracks 71C, 72C formed by the first and second plurality of under-surface laser damage lines 71, 72. As shown, the connection of cracks between the first plurality of under-surface damage lines, the second plurality of under-surface damage lines, and the third plurality of under-surface damage lines is also sufficient to cause further crack propagation and connection across the inter-group spacing 75.

[0229] In some embodiments, the third laser process for forming the third subsurface damage pattern is performed at a higher laser power level than the previous two processes to help extend the cracks to connect across the group spacing 75, which is wider than the spacings 76, 77 between the lines within each three-line group 74. The inventors have found that increasing the laser power during the third process is sufficient to connect not only cracks separated by 125 μm between laser-induced subsurface damage lines, but also cracks separated by 250 μm between laser-induced subsurface damage lines (e.g.,...). Figure 11D (As shown). This resulted in an approximately 25% increase in tool yield with a small cut loss (e.g., approximately 110 μm cut loss instead of 100 μm).

[0230] In some embodiments, all laser-induced surface damage lines may not be perpendicular to the flat portion of the main substrate (and

[11] ). [0] direction), within a range of approximately 1 to 5 degrees from the vertical line. For example, Figure 12 This is a top plan view of the crystalline material substrate 80, which includes a substrate plane 88 and a first, second, and third plurality of substantially parallel subsurface laser damage lines 81-83, which are scattered or intersected to form the first to third subsurface laser damage patterns. Each of the plurality of substantially parallel subsurface laser damage lines 81-83 is relative to the planar portion perpendicular to the main substrate (and

[11] ). The laser-damaged patterns are arranged in multiple groups of three lines 89, separated from each other by an inter-group spacing 85, which exceeds the spacing (or gap) 86, 87 between adjacent lines in each group of three lines 89. In one embodiment, a first plurality of parallel lines 81 may be formed with a pitch of 500 micrometers (i.e., the spacing between lines), and a second plurality of parallel lines 82 may be formed with a pitch of 500 micrometers and an offset of 250 micrometers relative to the first plurality of parallel lines 81. Subsequently, a third plurality of parallel lines 83 may be formed with a pitch of 500 micrometers and an offset of 125 micrometers relative to the first plurality of parallel lines 81. This arrangement produces a plurality of groups of three lines 89, which are separated from each group of three lines by a gap of 250 micrometers, and adjacent lines within each group of three lines are separated from each other by a gap of 125 micrometers. As shown, the laser-damaged lines 81-83 under the parallel surfaces of each group are parallel to each other.

[0231] Figure 13 This is a top plan view of the crystalline material substrate 90, which includes a substrate plane 98 and a first to fourth plurality of substantially parallel subsurface laser damage lines 91-94, which are scattered or intersected to form the first to fourth subsurface laser damage patterns, wherein all lines are parallel to each other and perpendicular to the substrate plane 98 (and

[11] [0] Direction). In some embodiments, the first to fourth plurality of subsurface laser-damaged lines 91-94 may each comprise lines with a pitch of 500 nm, wherein the second plurality of lines 92 are offset from the first plurality of lines 91 by 250 μm, the third plurality of lines are offset from the first plurality of lines 91 by 125 μm, and the fourth plurality of lines are offset from the first plurality of lines 91 by 375 μm. The end result is a 125 μm gap between each of the first plurality of lines 91 to the fourth plurality of lines 94. The four-line repeat group 95 consists of the first to fourth lines 91-94.

[0232] Forming similar to Figure 13 An alternative method for the crystalline material substrate 90 shown includes four laser under-surface damage formations, wherein each formation produces a line with a 500-micrometer pitch. After the first formation, the line formed by the second formation is offset by 125 micrometers from the first line, then the line formed by the third formation is offset by 250 micrometers from the first line, and then the line formed by the fourth formation is offset by 375 micrometers from the first line.

[0233] Figure 14 This is a top plan view of the crystalline material substrate 100, which includes a substrate plane 108 and includes a plurality of dispersed first to third subsurface laser damage lines 101, 103, forming first, second, and third subsurface laser damage patterns. The first and second plurality of lines 101, 102 are each parallel to each other and perpendicular to the main substrate flat portion 108 (and perpendicular to

[11] ). The third parallel line 103 is not parallel to the first and second parallel lines 101, 102 (e.g., having an angular difference in the range of 1 to 5 degrees), but does not intersect with either of the first and second lines 101, 102 within the substrate 100. In some embodiments, the first and second parallel lines 101, 102 are formed first, and then the third parallel line 103 is formed. In some embodiments, the first and second parallel lines 101, 102 each have a pitch of 500 micrometers, and the second parallel line 102 is offset by 250 micrometers relative to the first parallel line 101. The multi-line repeating group 104 consists of the first to third lines 101-103.

[0234] Although Figure 14 In some embodiments, subsurface laser damage lines do not intersect; however, in some implementations, one or more subsurface laser damage lines (e.g., formed during a subsequent laser damage formation process) may intersect with one or more other subsurface damage lines (e.g., formed during a previous or initial laser damage formation process). In some implementations, the relative angle between intersecting subsurface laser damage lines may be 4 to 30 degrees, or 5 to 20 degrees, or 5 to 15 degrees, or 5 to 10 degrees.

[0235] Figure 15 This is a top plan view of a crystalline material substrate 110, which includes a substrate plane 118 and includes dispersed first to third subsurface laser-damaged lines 111-113 forming first to third subsurface laser-damaged patterns. The first and second sets of lines 111 and 112 are each parallel to each other and not perpendicular to the main substrate flat portion 108 (e.g., having an angular difference in the range of 1 to 5 degrees), while the third set of lines 113 are perpendicular to the main substrate flat portion 118, but at least some (or all) of these lines do not intersect with the lines of the first and second sets of lines 111 and 112 within the substrate 110. In some embodiments, the first and second sets of parallel lines 111 and 112 each have a pitch of 510 micrometers, wherein the second set of parallel lines 112 is offset by 250 micrometers relative to the first set of parallel lines 111. A three-line repeating group 114 consists of the first to third lines 111-113.

[0236] Figure 16This is a top plan view of a crystalline material substrate according to one embodiment, the substrate including dispersed laser-damaged patterns on a first, second, and third surface defined therein, wherein all laser-damaged lines are parallel to each other, and the inter-group spacing of the laser-damaged lines is non-uniform on at least a portion of the substrate.

[0237] Figure 17 This is a top plan view of a crystalline material substrate according to one embodiment, the substrate including dispersed laser damage patterns on a first, second, and third surface defined therein, wherein all laser damage lines are parallel to each other and the laser damage lines exhibit variations in intra-group spacing, inter-group spacing, and group composition.

[0238] Figure 18 This is a top plan view of a crystalline material substrate according to one embodiment, the substrate including laser-damaged patterns formed sequentially on a first, second, and third surface defined therein, wherein the first and second sets of laser-damaged lines are parallel to each other, and the third set of laser-damaged lines are not parallel to the first and second sets of laser-damaged lines and intersect with the first and second sets of laser-damaged lines.

[0239] Figure 19 It is a top plan view of a crystalline material substrate including laser-damaged patterns formed sequentially on the first, second, and third surfaces, wherein each group of laser-damaged lines includes parallel lines, and the groups of laser-damaged lines are not parallel to each other. Although Figure 11A-19 Embodiments including three or four groups of multiple subsurface laser damage lines are shown; however, it should be understood that any suitable number of groups of subsurface laser damage lines can be provided. For example, in some embodiments, the first and second groups of subsurface laser damage lines can be distributed without a third and / or fourth group of subsurface laser damage lines. In some embodiments, the first and second groups of subsurface laser damage lines can be formed in the first and second phases, respectively, wherein each group of laser damage lines has a pitch of 250 micrometers, and the second group of laser damage lines is offset by 125 micrometers relative to the first group of laser damage lines.

[0240] In some embodiments, subsurface laser damage is distributed across multiple non-overlapping regions of the crystalline material by forming a first set of subsurface laser-damaged sites in non-overlapping first and second regions of the crystalline material, followed by forming a second set of subsurface laser-damaged sites in the first and second regions. At least some (or all) of the sites forming the second set of subsurface laser-damaged sites in the non-overlapping regions do not intersect with the sites of the first set of subsurface laser-damaged sites. Subsequently, one or more other sets of subsurface laser-damaged sites may be formed and distributed across the same non-overlapping first and second regions of the crystalline material. Although the first and second regions have been described, it should be understood that any suitable number of non-overlapping regions (e.g., three, four, five, six, or more regions) can be defined. In some embodiments, such regions may not only lack any overlap but may also be spaced apart from each other in a non-contact relationship (e.g., laterally spaced).

[0241] Figure 20A This is a top plan view of the crystalline material substrate 150, showing non-overlapping first, second, and third regions 150A-150C in which laser-damaged areas can be formed. Although shading has been added to the first and third regions 150A, 150C for illustrative purposes to emphasize the boundaries between the first and third regions 150A-150C, it should be understood that the actual crystalline material substrate 150 is generally uniform in color. Each region 150A-150C contacts a portion of the main flat portion 150' of the substrate 150. Although in Figure 20A-20D Three regions 150A-150C are shown, but any suitable number of regions, such as two, three, four, five, six or more, are envisioned, and such regions can be arranged in any suitable configuration, such as a one-dimensional array, a two-dimensional array, segments extending from the center point (e.g., wedge segments), etc.

[0242] Figure 20B After the formation of the first plurality of subsurface laser-damaged areas 151 in the first to third regions 150A-150C Figure 20A A top plan view of the crystalline material substrate 150. As shown, the laser-damaged areas 151 are arranged as substantially parallel lines, substantially perpendicular to the main flat portion 150' of the substrate 150. A plurality of laser-damaged areas 151 are provided in each of the first to third regions 150A-150C. Although Figure 20B Not shown, but should be understood as a laterally extending crack (e.g.) Figure 11B (As shown) can radiate from the laser-damaged area 151, but preferably do not connect with adjacent laser-damaged areas 151. In some embodiments, the multiple subsurface laser-damaged areas 151 can be formed in a first region 150A, then in a second region 150B, and finally in a third region 150C.

[0243] Figure 20C After the formation of the second plurality of subsurface laser-damaged areas 152 in the first to third regions 150A-150C Figure 20B A top plan view of the crystalline material substrate 150. As shown, the laser-damaged areas 152 of the second plurality of subsurface laser-damaged areas 152 are arranged as substantially parallel lines, substantially perpendicular to the main flat portion 150', and a plurality of laser-damaged areas 152 are provided in each of the first to third regions 150A-150C. Furthermore, each laser-damaged area 152 of the second plurality of subsurface laser-damaged areas 152 is substantially parallel to the first plurality of subsurface laser-damaged areas 151. Although Figure 20C Not shown, but it should be understood that laterally extending cracks can emanate from the individual laser-damaged regions 151, 152, but such cracks are preferably not connected between adjacent laser-damaged regions 151, 152. In some embodiments, the subsurface laser-damaged regions 152 of the plurality of subsurface laser-damaged regions 152 can be formed in the same order as the first subsurface laser-damaged region 151 (e.g., the subsurface laser-damaged region 152 can be formed in a first region 150A, then in a second region 150B, and finally in a third region 150C). In this way, the laser-damaged regions 152 of the second plurality of subsurface laser-damaged regions 152 are distributed among the laser-damaged regions 151 of the first plurality of subsurface laser-damaged regions 151.

[0244] Figure 20D This occurs after the formation of the third plurality of subsurface laser-damaged zones 153 in the first to third regions 150A-150C. Figure 20C A top plan view of the crystalline material substrate. As shown, the laser-damaged areas 153 of the third plurality of subsurface laser-damaged areas 153 are arranged as substantially parallel lines, substantially perpendicular to the main flat portion 150', and the plurality of laser-damaged areas 153 of the third plurality of subsurface laser-damaged areas 153 are arranged in each of the first to third regions 150A-150C. Each laser-damaged area 153 of the third plurality of subsurface laser-damaged areas 153 may be substantially parallel to the first and second plurality of subsurface laser-damaged areas 151, 152. The subsurface laser-damaged patterns provided by the first to third subsurface laser-damaged areas 151-153 form a plurality of three-line groups 154, which are spaced apart from each other by an inter-group spacing 154', which exceeds the spacing between adjacent laser-damaged areas 151-153 in each three-line group 154. Although Figure 20C Not shown, but it should be understood that laterally extending cracks can emanate from each laser-damaged zone 151-153, and the cracks extend laterally between all laser-damaged zones 151-153 (e.g. Figure 11D(As shown), to facilitate subsequent fracture of the upper portion of the substrate 150 from the remainder of the substrate 150. In some embodiments, subsurface laser-damaged regions 153 of the plurality of subsurface laser-damaged regions 152 may be formed in the same order as the first and second subsurface laser-damaged regions 151, 152 (e.g., subsurface laser-damaged regions 153 may be formed in a first region 150A, then in a second region 150B, and finally in a third region 150C). In this way, the laser-damaged regions 153 of the third plurality of subsurface laser-damaged regions 153 are distributed between the laser-damaged regions 151, 152 of the first and second plurality of subsurface laser-damaged regions 151, 152.

[0245] Parallel processing and / or laser beam separation

[0246] In some embodiments, multiple regions of a substrate can be processed simultaneously to form subsurface laser damage in multiple substrate regions, and / or multiple substrates can be arranged within a single tool for simultaneous or substantially simultaneous laser processing to enhance tool throughput. In some embodiments, one or more beam splitters can be used to split the output beam of a laser into multiple beams, which can be provided to different substrates or different regions of a single substrate to form subsurface laser damage therein using the methods disclosed herein. In some embodiments, multiple lasers can be used to simultaneously provide beams to multiple substrates or multiple regions of a single substrate to form subsurface laser damage therein using the methods disclosed herein.

[0247] Figure 21 This is a top plan view of a support 163 of a laser processing apparatus, configured to hold four substrates 155A-155D, in which subsurface laser damage can be formed using one or more lasers. As shown, each substrate 155A-155D includes a subsurface laser damage pattern defined therein, comprising first, second, and third plurality of substantially parallel lines 156-158. Three laser damage patterns are combined to form a plurality of three-line groups 156, which are separated from each other by an inter-group spacing 160, which exceeds the spacing 161, 162 between adjacent lines in each three-line group 159. In some embodiments, the laser damage pattern can be formed in the first substrate 155A and the third substrate 155C using a first laser or a first separated laser beam portion, and in the second substrate 155B and the fourth substrate 155D using a second laser or a second separated laser beam portion. In some embodiments, the support 163 carrying the substrates 155A-155D is configured to move (e.g. in two (x, y) lateral directions) while restricting lateral movement of one or more lasers and / or their focusing optics (but may be subject to vertical (z-direction) movement).

[0248] Figure 22A This is a top plan view of a single substrate 164 processed by a laser beam, the laser beam being divided into multiple portions to simultaneously form subsurface laser-damaged areas according to a first subsurface laser-damaged pattern in multiple regions of the substrate 164. As shown, the substrate 164 includes multiple regions 164A-164C (e.g., similar to...). Figures 20A-20C The initial laser damage formation step involves impacting two separate laser beam portions to simultaneously form laser-damaged areas 165' in the first and second regions 164A, 164B. The substrate 164 may be laterally indexed relative to the laser (e.g., in the direction opposite to the right-hand arrow). Subsequent laser damage formation steps involve impacting the two separate laser beam portions to simultaneously form laser-damaged areas 165'' in the first and second regions 164A, 164B. This process is repeated to form additional laser-damaged areas 165''', 165'''' in the first and second regions 164A, 164B, ultimately covering the first, second, and third regions 164A-164C to form a first subsurface laser damage pattern. This process can then be repeated to form second and third subsurface laser damage patterns, which are dispersed from the first subsurface laser damage pattern. The first and second separate laser beam portions can be used to form a subsurface laser damage pattern distributed across the entire substrate 164 in half the time it would take to form a pattern by a single, unseparated laser beam. Figure 22B This is a top plan view of two substrates 166A and 166B, supported by a bracket 168 and treated with a laser beam. The laser beam is split into two parts to simultaneously form subsurface laser damage according to at least one subsurface laser damage pattern in the two substrates 166A and 166B. An initial laser damage formation step includes impacting the two split laser beam portions to simultaneously form laser damage areas 167' in the first and second substrates 166A and 166B. The bracket supporting the substrates 166A and 166B may be laterally indexed relative to the laser (e.g., in the direction opposite to the right-hand arrow), and a subsequent laser damage formation step includes impacting the two split laser beam portions to simultaneously form laser damage areas 167'' in the first and second substrates 166A and 166B. This process is repeated to form additional laser damage areas 167''', 167'''' in the first and second substrates 166A and 166B, ultimately covering the first and second substrates 166A and 166B to form a first subsurface laser damage pattern therein. The process can then be repeated to form second and third under-surface laser damage patterns in substrates 166A and 166B, respectively, which are distributed with the first under-surface laser damage pattern.

[0249] Laser damage under overlapping surfaces at different depths

[0250] In some embodiments, initial subsurface laser damage centered at a first depth can be formed within the crystalline material substrate, and additional subsurface laser damage centered at a second depth can be formed within the substrate, wherein the additional subsurface laser damage is substantially aligned with the initial subsurface laser damage, and at least a portion of the vertical extent of the additional subsurface laser damage overlaps with at least a portion of the vertical extent of the initial laser damage. Reiterating, one or more subsequent processes configured to impart laser damage at different depths can be added on top of one or more prior processes to provide subsurface laser damage with overlapping vertical extents. In some embodiments, overlapping subsurface laser damage incomplete in one or more prior subsurface laser damage formation steps can be added in response to a determination prior to fracture (e.g., by optical analysis). Forming overlapping subsurface laser damage at different depths can be combined with any other method steps herein, including (but not limited to) forming multiple dispersed subsurface laser damage patterns.

[0251] Figure 23A This is a schematic cross-sectional view of a crystalline material substrate 170, which includes a first subsurface laser damage pattern 173 centered at a first depth relative to a first surface 171 of the substrate 1770, wherein the subsurface damage pattern 173 is generated by focused emission of a laser 179. The first subsurface laser damage pattern 173 has a vertical extent 174 that remains within the substrate 170 between the first surface 171 and the opposing second surface 172. Figure 23B After forming the second surface laser damage pattern 175 centered at the second depth and aligned with the first surface laser damage pattern 173, Figure 23A A cross-sectional schematic diagram of the substrate, wherein the vertical extension 176 of the second damage pattern 175 overlaps with the vertical extension 174 of the first damage pattern 173 in the damage overlap area 177. In some embodiments, subsequent fracture of the crystalline material 170 may occur along or through the damage overlap area 177.

[0252] Non-overlapping surface laser damage is formed at different depths

[0253] In some embodiments, subsurface laser damage lines can be formed at different depths within the substrate without aligning with other (e.g., previously formed) subsurface laser damage lines, and / or without causing the vertical extent of initial and subsequent laser damage to overlap in features. In some embodiments, the scattering pattern of the subsurface laser damage may include groups of laser lines, with different groups focused at different depths relative to the substrate surface. In some embodiments, the focusing depth of laser emission within the substrate differs between different groups of laser lines (e.g., at least two different groups such as first and second groups, first to third groups, first to fourth groups, etc.) by a distance ranging from about 2 micrometers to about 5 micrometers (i.e., about 2 µm to about 5 µm).

[0254] Laser tool calibration

[0255] One of the main drivers of cut loss is subsurface laser damage beneath the primary fracture zone on the ingot side. Typically, increased subsurface laser damage increases cut loss. A potential reason for increased subsurface laser damage is the inability to adequately compensate for the optical properties of the crystalline material.

[0256] In some implementations, laser calibration can be performed each time a crystalline material substrate (e.g., an ingot) is supplied to the laser tool before forming subsurface laser damage in the laser tool. This calibration can utilize variable height adjustment to achieve an initial state at the optimal focus of the laser beam forming the upper surface of the crystalline material substrate, followed by adjustment of the laser tool's aperture or calibration ring according to the subsequent state, which corresponds to the desired depth of subsurface laser damage formation in the crystalline material.

[0257] chip images

[0258] Figure 24A It is to use the thermally induced fracture method described in this article to fracture from the carrier (i.e. Figure 24B The image shows a perspective view of the SiC wafer 180 after separation from the thermoplastic-bonded sapphire carrier 181. Both the wafer 180 and the carrier 181 have a diameter of 150 mm. No wafer fracture was observed after thermally induced fracture. Figure 24C yes Figure 24A A partially toned version of a SiC wafer photograph to emphasize the contrast between the central doped ring 182 and the outer portion 183 of the ring in the SiC wafer 180. Figure 24D Shown with dashed ellipse annotation Figure 24CThe image illustrates the boundary between the central doped ring 182 and the annular outer portion 183 of the SiC wafer 180. The doped ring 182 represents a region with increased doping relative to the annular outer portion 183 of the SiC wafer. Since doped semiconductor materials (e.g., SiC) exhibit increased IR wavelength absorption, higher laser power may be advantageous compared to the annular outer portion 183 when seeking to form subsurface laser damage in the SiC wafer within the doped ring 182. In some embodiments, the presence of conditions indicating inhomogeneous doping of the crystalline material on at least a portion of the substrate surface can be detected, such as by optically detecting changes in light reflection or absorption to determine the presence of at least one first doped region and at least one second doped region (e.g., the doped ring 182 and the annular outer portion 183). Subsequently, in response to the detection of conditions indicating non-uniform doping of the crystalline material, the laser power can be varied during the formation of the subsurface laser damage pattern to provide laser emission at a first average power when forming subsurface laser damage in a first doped region (e.g., doped ring 182) and to provide laser emission at a second average power when forming subsurface laser damage in a second doped region (e.g., ring outer 183), wherein the first average power level and the second average power level are different from each other.

[0259] Figure 25 This is a perspective photograph of the Si facet of a SiC wafer separated from an ingot through a process involving the formation of subsurface laser damage and subsequent separation. The inset portion (top right) depicts intentionally separated fragments of the SiC wafer, including the edges depicted in the subsequent scanning electron microscope (SEM) image.

[0260] Figure 26 It was obtained at a 15-degree tilt angle. Figure 25 A 45x magnified SEM image of a portion of a SiC crystal fragment, with superimposed arrows indicating [1] 00] and [11 The direction of the [0] crystal plane. The laser line is perpendicular to

[11] . The 0 direction is spaced approximately 250 micrometers apart. Figure 27 It was obtained at a 15-degree inclination angle. Figure 25 A 1300x magnified SEM image of a portion of a SiC wafer fragment. Figure 28 yes Figure 25 A 350x magnified SEM image of a portion of a SiC wafer fragment, acquired at a 15-degree tilt angle. (Example) Figure 28 As shown, the off-axis cleavage planes are roughly related to the laser spacing, but are inconsistent across the entire wafer surface. This can be attributed at least in part to the variation in the laser line positions on the cleavage planes. In this wafer, fracture is induced at polycrystalline inclusions.

[0261] Figure 29 yes Figure 25A 100x magnified SEM image of a portion of a SiC wafer fragment acquired at a 2-degree tilt angle. Figure 30 It was obtained at a 2-degree inclination angle. Figure 25 A 1000x magnified SEM image of a portion of a SiC wafer fragment. Figure 29 and 30 The laser damage is quite shallow compared to the surface features along the fracture zone. The resulting changes in fracture damage are visible, particularly in... Figure 30 The central part.

[0262] Figure 31A yes Figure 25 A confocal laser scanning micrograph of a small central portion of a SiC wafer, showing the location of superimposed crosshairs marking the “grooves” formed by laser scanning. Figure 31B yes Figure 31A A partial surface profile of a SiC wafer. (Reference) Figure 31B The change in the position of the laser line relative to the SiC cleavage surface can be observed.

[0263] Figure 32A yes Figure 35 A confocal laser scanning micrograph of the larger top portion of a SiC wafer (as shown in the figure), with superimposed crosshair markings indicating the location of “grooves” or lines formed by laser scanning. Figure 32B yes Figure 32A A surface profile of the portion near the top of a SiC wafer. Figure 32B In the first pair of lines corresponding to laser damage (represented as cross lines within ellipse 200) are separated by a depth of more than 30 micrometers, and the second pair of lines corresponding to laser damage (represented as cross lines within ellipse 201) are separated by a depth of more than 20 micrometers. Figure 32A and 32B The irregular spacing between the laser lines is shown, wherein the individual lines in the first pair (within ellipse 200) are closer to each other, while the individual lines in the second pair (within ellipse 201) are closer to each other than the laser damage lines shown.

[0264] Figure 33A yes Figure 25 A confocal laser scanning micrograph of the larger bottom portion of a SiC wafer (as shown in the figure), with superimposed crosshair markings indicating the location of “grooves” formed by laser scanning. Figure 33B yes Figure 33A A surface profile of the portion near the bottom of a SiC wafer. Figure 33B The display shows the lateral distance variation between adjacent laser-damaged line pairs, with one pair spaced 334 micrometers apart and the other pair spaced 196 micrometers apart, but the maximum depth variation is 13 micrometers.

[0265] Substrate fracture following subsurface laser damage.

[0266] As discussed earlier herein, subsurface laser damage can be formed within a crystalline material substrate to prepare a substrate for fracture to remove at least one thin layer of crystalline material (e.g., a wafer) from the substrate. While examples of specific fracture techniques (e.g., cooling a CTE mismatch carrier bonded to the substrate, impinging ultrasonic waves on the substrate, or applying a bending moment to a carrier mounted on the substrate) are described below, it should be understood that the various subsurface laser damage formation techniques described herein can be used with any suitable fracture technique, including those known to those skilled in the art.

[0267] Fracture of a rigid carrier with carrier / substrate CTE mismatch by cooling

[0268] Figures 34A-34F The steps of a carrier-assisted method for fracture crystalline materials according to one embodiment of the present disclosure are shown, the method utilizing a rigid carrier having a larger CTE than the crystalline material bonded to the crystalline material. Figure 34A This is a schematic side cross-sectional view of a rigid carrier 202 having an adhesive material layer 198 bonded to a first surface 203 of the rigid carrier 202 and a second surface 204 opposite to the first surface 203.

[0269] Figure 34B It includes Figure 34A A cross-sectional schematic diagram of an assembly 188 of a rigid carrier 202 and an adhesive material 198 bonded to a crystalline material substrate 190 having a subsurface laser-damaged region 196 therein. The rigid carrier 202 has a larger diameter or lateral extent than the substrate 190. The substrate 190 includes a first surface 192 adjacent to the adhesive material 198 and an opposing second surface 194, with the subsurface laser-damaged region 196 closer to the first surface 192 than to the second surface 194. The adhesive material 198 extends between the first surface 192 of the crystalline substrate 190 and the first surface 203 of the rigid carrier 202. The adhesive material 198 can be cured according to the requirements of a selected bonding method (e.g., thermosetting adhesive bonding, compression-assisted UV bonding, chemically reactive bonding, etc.). In some embodiments, a second carrier (not shown) may be bonded to a second surface 194 of the substrate 190, wherein the second carrier may optionally not be wider than the substrate 190 and / or the CTE-matched substrate.

[0270] Figure 34C This occurs after the second surface 204 of the rigid carrier 202 is positioned on the support surface 208 of the cooling device. Figure 34BA cross-sectional schematic diagram of the components shows the cooling device configured as a cooling chuck 206 receiving cooling liquid. Contact between the rigid carrier 202 and the cooled chuck 206 allows heat transfer from the rigid carrier 202 to the cooled chuck 206. During the cooling process, because the CTE of the carrier 202 is greater than that of the substrate 190, the rigid carrier 202 will laterally contract to a degree greater than that of the crystalline material substrate 190, causing the carrier 202 to apply shear stress to the substrate 190. Due to the presence of subsurface laser damage 196 near the adhesive layer 198 that bonds the rigid carrier 202 to the substrate 190, the shear stress applied to the substrate 190 causes the crystalline material to fracture along or near the subsurface laser damage area 196.

[0271] In some embodiments, the cooled chuck 206 has a smaller diameter than the rigid carrier 202. While the cooled chuck 206 can be supplied with a cooling liquid, the rigid carrier 202 does not necessarily need to reach liquid nitrogen temperature (-160°C) to successfully achieve thermally induced fracture of the crystalline material substrate 190. Favorable separation results have been obtained by fracturing single-crystal SiC material supported by a single-crystal sapphire substrate using a cooled chuck maintained at -70°C. Such temperatures can be maintained using various cooling liquids received from a two-phase pumped evaporative cooling system, such as liquid methanol (which remains flowable above its freezing point at -97°C). Favorable separation results have also been obtained by cooling the carrier, binder, and substrate in a refrigerator maintained at -20°C, where such temperatures can be maintained using a single-phase evaporative cooling system. The ability to use a single-phase evaporative cooling system or a two-phase pumped evaporative cooling system instead of liquid nitrogen significantly reduces operating costs.

[0272] Figure 34D This is a schematic cross-sectional view of the remaining portion of the crystalline material substrate 190A, separated from a bonding assembly comprising a rigid carrier 202, adhesive material 198, and a portion of the crystalline material 210 removed from the remainder of the substrate 190A, after the crystalline material has fractured along the laser-damaged area below the surface. The remaining portion of the crystalline material substrate 190A is defined by a new first surface 193 (with residual laser damage 196A) opposite to the second surface 194. Correspondingly, the removed portion of the crystalline material 210 is defined by a new second surface 212 (with residual laser damage 196B) opposite to the first surface 192. Subsequently, the bonding assembly 215, comprising the rigid carrier 202, adhesive material 198, and the removed portion of the crystalline material 160, can be withdrawn from the cooled chuck 206.

[0273] Figure 34E It was removed from the liquid-cooled chuck 206. Figure 34DA cross-sectional schematic diagram of the bonding component 215. The removed portion of the crystalline material 210, held attached to the rigid carrier 202, advantageously provides mechanical support to allow one or more surface treatment steps (e.g., grinding, polishing, etc.) to be performed on the new surface 212 to remove residual laser damage 196B and achieve the desired thickness of the crystalline material 210 (e.g., via grinding, optionally followed by chemical mechanical planarization and / or polishing steps). In some embodiments, laser damage removal and thinning may include sequential grinding / polishing operations, and any suitable polishing and cleaning steps to prepare the new surface 212 for subsequent operations (e.g., surface implantation, laser marking (e.g., along the wafer plane), epitaxial layer formation, metallization, etc.).

[0274] Figure 34F This is a schematic cross-sectional view of the removed portion of the crystalline material 210, supported by the upper surface 218 of a heated vacuum chuck 216, where, after softening and releasing the adhesive material 198 at elevated temperatures, the rigid carrier 202 and the adhesive material 198 are laterally translated away from the removed portion of the crystalline material 212. Specifically, the heated vacuum chuck 216 can heat the adhesive material 198 to a sufficient temperature to soften and / or flow, allowing the rigid carrier 202 to laterally translate away from the removed portion of the crystalline material 212, which is temporarily held in one position by the heated vacuum chuck 216, when external shear stress is applied to the second surface 204 of the rigid carrier 202. Thereafter, the heated vacuum chuck 216 can be turned off, and the removed portion of the crystalline material 212 becomes a self-supporting material. If desired, any residue from the adhesive 198 can be removed and cleaned from the first surface 203 of the rigid carrier 202, and the rigid carrier 202 can optionally be reused for another fracture operation. The removed crystalline material can then be used as a growth substrate for depositing one or more epitaxial layers and conductive metal layers to form a device wafer, which is then monolithically assembled to form discrete semiconductor devices.

[0275] Fracture caused by ultrasonic energy

[0276] Another method for achieving fracture along a laser-induced subsurface damage zone of a crystalline material bonded to a rigid carrier involves applying ultrasonic energy to the crystalline material while it is in a bonded state. Figure 35This is a schematic cross-sectional view of component 188A, which includes crystalline material 190A with subsurface laser damage 196A, bonded to a rigid carrier 202A using an intervening adhesive material 198A, wherein component 188A is arranged in a liquid pool 225 of ultrasonic generator device 220. Device 220 also includes a container 222 arranged to contact the ultrasonic generating element 224, container 222 containing the liquid bath 225. The presence of rigid carrier 202A can reduce or eliminate fracture of crystalline material 190A when subjected to ultrasonic energy, especially if residual stress remains between rigid carrier 202A and crystalline material 190A before separation (e.g., due to CTE mismatch). This residual stress reduces the amount of ultrasonic energy required to induce fracture of the crystalline material, thereby reducing the likelihood of material fracture.

[0277] Fracture caused by mechanical force

[0278] In some embodiments, fracture of the crystalline material bonded to the rigid carrier can be facilitated by (i) applying a mechanical force (e.g., optionally positioned at one or more points) near at least one edge of the carrier. This force can impart a bending moment in at least a portion of the carrier, which is transmitted to the subsurface laser-damaged region to induce fracture. Figures 36A-36C An exemplary embodiment is shown.

[0279] Figures 36A-36C This is a cross-sectional schematic diagram illustrating the steps of fracturing a crystalline material substrate 236 having subsurface laser damage 233 by applying mechanical force near one edge of a carrier 238, the substrate 236 being bonded to the carrier. The bonding assembly includes the crystalline material substrate 236 having a subsurface laser damage region 233 bonded between rigid carriers 238, 238'. Each rigid carrier 238, 238' includes a laterally projecting protrusion 239, 239' aligned with a flat portion 235 of the substrate 236, thereby providing a locally enlarged boundary region defining a groove 231 into which a tool 219 can be inserted. Figure 36A This shows the state before the tool 219 is inserted into the recess 191. Figure 36B The diagram shows the state after tool 219 is inserted into the recess when tool 216 is tilted upwards, thereby applying a tensile force in a direction tending to promote separation between rigid supports 238, 238', thereby applying a bending moment M on at least one support 238. In some embodiments, substrate 236 comprises a material having a hexagonal crystal structure (e.g., 4H-SiC), and the bending moment M is oriented perpendicular to the hexagonal crystal structure

[11] . Within ±5 degrees in the [0] direction (or equivalently within ±5 degrees in the direction parallel to [1-100]). Figure 36CThis illustrates the state of the crystalline substrate 236 after initial fracture along the subsurface laser-damaged region 233, whereby the upper portion 236 of the crystalline material remains bonded to the upper carrier 238, and the lower portion 236B of the crystalline material remains bonded to the lower body 238', with the upper carrier 238 tilted upward relative to the lower body 238'. This fracture results in a first bonding assembly 229A (including the upper carrier 238 and upper portion 236A of the crystalline material) separating from the second bonding assembly 229B (including the lower body 238' and lower portion 236B of the crystalline material). In some embodiments, mechanical forces may be applied near the opposing edges of the rigid carrier bonded to the substrate to facilitate fracture of the crystalline material with subsurface laser damage bonded to the carrier.

[0280] It should be noted that combining two or more fracture techniques (e.g., CTE mismatch and ultrasonic-induced fracture; or CTE mismatch and mechanically induced fracture; or ultrasonic-induced and mechanically induced fracture) is particularly considered. In some embodiments, the liquid in the ultrasonic bath may be cooled before or during the application of ultrasonic energy. The amount of mechanical force required to complete the fracture may be affected by the CTE difference between the substrate and the carrier. In some embodiments, CTE difference and mechanical force may be combined. If the CTE difference between the carrier and the substrate is small or nonexistent (i.e., matched CTE), more mechanical force may be required to complete the fracture. Conversely, if the CTE mismatch is large, reduced mechanical force or no mechanical force may be required to complete the fracture.

[0281] Device wafer separation process

[0282] In some embodiments, a laser and carrier-assisted separation method can be applied to the crystalline material after at least one epitaxial layer (and optionally at least one metal layer) has been formed on the crystalline material as part of an operational semiconductor-based device. This device wafer separation process is particularly advantageous for increasing the yield of the crystalline material (and reducing waste) by significantly reducing the need to grind away the substrate material after device formation.

[0283] Figure 37A-37O This is a cross-sectional schematic diagram illustrating the steps of a device wafer separation process, according to which a thick wafer is broken from a crystalline material, at least one epitaxial layer is grown on the thick wafer, and the thick wafer is broken to form first and second bonding assemblies, each bonding assembly including a carrier and a thin wafer separated from the thick wafer, wherein the first bonding assembly includes at least one epitaxial layer as part of an operating semiconductor-based device.

[0284] Figure 37A A crystalline material substrate 240 is shown, having a first surface 241 and a surface laser damage 243 disposed at a certain depth relative to the first surface. Figure 37BThis shows the effect after applying adhesive material 244 to the first surface 241. Figure 37A The substrate is 240. Figure 37C This illustrates the process of bonding the rigid carrier 246 to the substrate 240 using adhesive material 244. Figure 37B The projects described in the text. Figure 37D The diagram illustrates the remaining portion of the substrate 240 after laser damage 243 along the subsurface of the fractured substrate 240 (e.g., using one or more methods disclosed herein). Figure 37D The remaining portion of the project is separated from the bonding assembly comprising a carrier 246, an adhesive material 244, and a portion of crystalline material (e.g., a thick wafer) 242 removed from the substrate 240. In some embodiments, the thick wafer 242 may have a thickness in the range of about 350 to 750 micrometers. The exposed surfaces 243A, 243B of the thick wafer 242 and the remainder of the substrate 240 may exhibit surface irregularities, which can be reduced by surface treatment steps such as grinding, CMP, polishing, etc. Figure 37E A thick wafer 242 is shown after detachment and removal from carrier 246, wherein the thick wafer 242 includes a vertical edge profile. The vertical edges of the wafer are prone to breakage, generating unacceptable edge debris and particles during wafer processing. To reduce the risk of breakage, the wafer edges can be edge-ground to produce non-vertical wafer edges with beveled or rounded edges. Figure 37F A thick wafer 242 is shown, which is supported between opposing upper and lower gripping portions 248A, 248B of a turntable near a rotary profile grinding tool 249 having a concave cutting surface 249A (e.g., impregnated with diamond particles) configured to give the thick wafer 242 a rounded edge profile 247. Figure 37G A thick wafer 242 is shown after edge grinding (also known as edge shaping), wherein the thick wafer includes a circular edge 247 that provides the boundary between the first and second wafer surfaces 251, 252.

[0285] Figure 37H This illustrates the process after one or more epitaxial layers 253 have been deposited on or over the first surface 251 of a thick wafer 251. Figure 37G The thick wafer 242. Due to the incompatibility between the binder and the inherent high temperature of the epitaxial layer, Figure 37D The carrier shown does not exist. Figure 37I This illustrates the process of forming conductive (e.g., metal) contacts 254 over the epitaxial layer 253 to form at least one operational semiconductor device. Figure 37HThe structure includes a thick wafer 242 that still has rounded edges 247. Typically, grinding is performed on the second surface 252 to thin the thick wafer 242 to a suitable thickness for the resulting device (e.g., 100 to 200 micrometers for a Schottky diode or MOSFET). The method disclosed herein reduces the need for wafer grinding and instead utilizes laser and carrier-assisted separation to remove a portion of the thick wafer, allowing the thick wafer to be surface-finished and used to fabricate another operating semiconductor device.

[0286] The inventors have discovered that the presence of circular edges 247 on the thick wafer 242 inhibits the controlled formation of subsurface laser damage to adjacent edges 247 because the circular profile negatively affects laser focusing and depth control. To address this issue, the circular edges 247 of the thick wafer 242 can be removed before further laser processing. Figure 37J It shows Figure 37I The structure is subjected to grinding using an edge grinder 256 to grind away the circular edge 247 and to give a substantially vertical edge 255 extending between the first and second surfaces 251, 252 of the thick wafer 242, wherein the epitaxial layer 253 and the contact 254 are disposed on the first surface 251.

[0287] Figure 37K This illustrates the process after applying a temporary adhesive material 257 over the first surface 251, epitaxial layer 253, and contact 254 of the thick wafer 242. Figure 37J The structure is designed to receive and bond the first carrier. Figure 37L This illustrates the process after adding a first carrier 258 to a temporary adhesive material 257 and after forming subsurface laser damage 259 within the thick wafer 242 via laser emission incident and focused through the second surface 252 of the thick wafer 242. Figure 37K The structure. Figure 37M This illustrates the effect of laser damage 259 near the subsurface surface on the second surface 252 of the rigid second carrier 260 bonded to the thick wafer 242. Figure 37L The structure. For separation purposes, the rigid second carrier 260 will act as a front carrier intended to remove a portion (i.e., a layer) of the thick wafer 242.

[0288] In some embodiments, laser emission can be applied to a thick wafer of a standalone device, and the first and second carriers can be bonded to the front and back sides of the thick wafer substantially simultaneously. In some embodiments, an adhesive material can be applied to one or both of the front and back sides on the carriers or wafer.

[0289] Figure 37NThis illustrates the process following the application of at least one fracture process as disclosed herein to fracture the thick wafer 242 along the subsurface laser damage 259 to produce the first and second bonded subassemblies 262A, 262B. Figure 37M The project. The first bonding sub-assembly 262A includes a first thin wafer portion 242A (with Figure 37M The second bonding sub-assembly 262B includes a second thin wafer portion 242B (separated from the thick wafer 242), an epitaxial layer 253, a contact 254, a temporary adhesive material, and a first carrier 258. The second bonding sub-assembly 262B includes a second thin wafer portion 242B (with...). Figure 37M (Separation of the thick wafer 242) and the second carrier 260. The exposed surfaces 259A, 259B of the thin wafer portions 242A, 242B may exhibit surface irregularities due to laser damage and / or breakage, which can be reduced by conventional surface treatment steps (e.g., grinding, CMP and / or polishing). Figure 37O An operable semiconductor device 264 is shown obtained from the first bonding subassembly 262A by removing the temporary adhesive 257 and the first carrier 258. This figure also includes a second thin wafer portion 242B after the removal of the second carrier 260, for fabrication of the second thin wafer portion 242B for further processing (e.g., epitaxial growth).

[0290] Exemplary methods including reusing carrier wafers

[0291] Figure 38 This is a flowchart schematically illustrating the steps of the method according to the invention. Starting from the upper left, laser 266 can focus laser emission below a first surface 272 of a thick crystalline material substrate 270 (e.g., a SiC ingot) to create a subsurface laser-damaged region 268. Subsequently, a carrier wafer 224 can be bonded to the first surface 272 of the crystalline material substrate 270. The carrier wafer 274 includes a first surface 276 (adjacent to the first surface 272 of the substrate 270) and a second surface 278 opposite to the first surface 276 of the carrier wafer 274. This bonding between the carrier wafer 278 and the crystalline material substrate 270 can be achieved by any of the methods disclosed herein, such as adhesive bonding or anodic bonding. Details regarding the anodic bonding between the crystalline material substrate and the carrier are disclosed in U.S. Patent Application Publication No. 2016 / 0189954, the contents of which are incorporated herein by reference. Subsequently, a fracture process as disclosed herein (e.g., cooling the CTE-mismatched carrier, applying ultrasonic energy, and / or applying mechanical force) is applied to fracture the crystalline material 270 along the subsurface laser-damaged region 218, causing the crystalline material portion 280 bonded to the carrier wafer 278 to separate from the remainder of the crystalline material substrate 270A. The newly exposed surface 282A of the remaining portion of the crystalline material substrate 270A with residual laser damage is polished smooth and cleaned, and returned to the beginning of the process (at... Figure 38(The upper left part). Furthermore, the newly exposed surface 284 of the removed crystalline material 280 is polished smooth while adhering to the carrier 274. Subsequently, the carrier wafer 274 can be separated from the portion from which the crystalline material 280 was removed, and the crystalline material 280 can undergo epitaxial growth of one or more layers to form an epitaxial device 280', while the carrier wafer 274 is cleaned and returned to the beginning of the process (in the upper left part). Figure 38 (the upper left part) to achieve the removal of another relatively thin portion of the crystalline material substrate 270.

[0292] Figure 39 yes Figure 38 A schematic cross-sectional view of a portion of a crystalline material substrate (e.g., a SiC ingot) 270 shows subsurface laser damage 268, with superimposed dashed lines identifying the intended nick-loss material region 290. The intended nick-loss material region 290 includes laser damage 268, plus material 284 to be mechanically removed (e.g., by grinding and polishing) from the lower surface 288 (e.g., a Si-terminating surface) of the crystalline material portion 280 (e.g., a Si-terminating surface) to separate it from the substrate 270, plus material 286 to be mechanically removed (e.g., by grinding and polishing) from the upper surface 282A (e.g., a C-terminating surface) of the remaining portion 270A of the substrate 270. The lower surface 288 of the crystalline material portion 280 is opposite its upper surface 272. In some embodiments, for SiC, the entire nick-loss material region may have a thickness in the range of 80-120 micrometers to provide sufficient thickness for further processing of the substrate upper surface 282A and the wafer lower surface 288.

[0293] Material processing through multiple grinding tables / steps

[0294] In some embodiments, crystalline material subjected to laser treatment and fracture can be further processed with multiple surface grinding steps to remove subsurface damage and edge grinding to impart beveled or rounded edge profiles, wherein the order of the grinding steps is selected and / or a protective surface coating is used to reduce the likelihood of imparting additional surface damage and to prepare the crystalline material wafer for chemical mechanical planarization. These steps can be performed, for example, using a material processing apparatus according to embodiments disclosed herein, wherein exemplary apparatus includes a laser processing stage, a fracture stage, a plurality of coarse grinding stages arranged in parallel downstream of the fracture stage, and at least one fine grinding stage arranged downstream of the coarse grinding stages. When processing wafers cut by a wire saw, edge grinding is typically performed before surface grinding or polishing to remove wire saw-cut surface damage. However, the inventors have found that edge grinding of substrate portions (e.g., wafers) with laser-damaged and fractured damage increases the likelihood of substrate portion cracking. While not wishing to be bound by any particular theory regarding the cause of this phenomenon, it is believed that if edge grinding is performed before at least some surface treatments (grinding and / or polishing), the exposed cleavage planes resulting from surface fracture make the surface prone to cracking. Therefore, it has been found beneficial to perform at least some surface treatment (e.g., grinding and / or polishing) before edge grinding.

[0295] It has been found that the coarse grinding step (i.e., removing laser damage and fracture damage along the fracture surface of the substrate portion and bulk substrate) tends to take significantly longer to complete than the preceding laser processing and fracture steps, and also significantly longer than the subsequent fine grinding step. To address this, multiple coarse grinding stages are arranged in parallel to eliminate bottlenecks in the fabrication of multiple wafers from bulk crystalline materials (e.g., ingots). In some embodiments, robotic processors may be arranged upstream and downstream of the multiple coarse grinding stages to control the loading and unloading of the substrate portion. In some embodiments, a carrier bonding stage may be positioned between the laser processing stage and the fracture stage, and a carrier removal stage may be positioned upstream (directly or indirectly) of the edge grinding stage. Ideally, the carrier should remain bonded to the substrate portion during at least some surface grinding steps to reduce the likelihood of fracture, particularly for thin substrate portions (e.g., wafers); however, it is preferable to remove the carrier before edge grinding (or before applying a protective coating to the wafer before edge grinding).

[0296] In some embodiments, the carrier bonding stage may use a carrier pre-coated with a temporary bonding medium, align and press the carrier onto the substrate surface, and subject the bonding medium to necessary conditions (e.g., heat and pressure) to achieve bonding between the carrier and the substrate. Alternatively, the carrier bonding stage may include a coating stage that can be used to coat the carrier or substrate as needed.

[0297] Figure 40This is a schematic diagram of a material processing apparatus 300 according to one embodiment, including a laser processing stage 302, a carrier bonding stage 303, a material fracture stage 304, a plurality of parallelly arranged rough grinding stages 308A, 308B, a fine grinding stage 312, a carrier removal stage 313, and a CMP stage 314. The laser processing stage 302 includes at least one laser and a support for at least one substrate, the support being arranged to receive at least one laser beam for forming subsurface laser damage in a crystalline material (e.g., an ingot). The carrier bonding stage 303 is configured to bond a crystalline material (with subsurface laser damage therein) to at least one rigid carrier. The fracture stage 304 is arranged to receive one or more components (each component including a substrate bonded to the rigid carrier) from the carrier bonding stage 303 and fracture at least one substrate along a subsurface laser damage region to remove a portion of the substrate (which may resemble a wafer bonded to a carrier). First and second rough grinding stages 308A and 308B are arranged in parallel downstream of the fracture stage 304, wherein a first mechanical processor 306 is configured to alternately feed substrate portions (as part of a bonding assembly) received from the fracture stage 304 to either the first rough grinding stage 308A or the second rough grinding stage 308B. Downstream of the first and second rough grinding stages 308A and 308B, a second mechanical processor 310 is provided to feed the coarsely ground substrate portions (as part of a bonding assembly) to a fine grinding stage 312. A carrier removal stage 313 is disposed downstream of the fine grinding stage 312 and is used to separate the ground substrate portions from the carrier. A chemical mechanical planarization (CMP) stage 314 is disposed downstream of the carrier removal stage 313 to prepare the substrate portions for further processing, such as cleaning and epitaxial growth. The CMP stage 314 is used to remove residual damage after fine grinding and itself removes residual damage after rough grinding. In some embodiments, each coarse grinding stage 308A, 308B includes at least one grinding wheel with a grinding surface of less than 5000 grit, and the fine grinding stage 312 includes at least one grinding wheel with a grinding surface of at least 5000 grit. In some embodiments, each coarse grinding stage 308A, 308B is configured to remove a thickness of 20 micrometers to 100 micrometers of crystalline material from a portion of crystalline material (e.g., a wafer), and the fine grinding stage 312 is configured to remove a thickness of 3 micrometers to 15 micrometers of crystalline material. In some embodiments, each coarse grinding stage 308A, 308B and / or the fine grinding stage 312 may include multiple grinding substages, wherein different substages include grinding wheels for different purposes.

[0298] It can improve the situation based on Figure 40 The equipment is designed to adapt to edge grinding, giving crystalline substrate portions (such as wafers) a rounded or beveled edge profile. This edge profile reduces the risk of wafer edge breakage. When the substrate portion is bonded to a carrier, edge grinding may not be performed; therefore, the carrier removal stage can be positioned upstream (directly or indirectly) of the edge grinding stage.

[0299] Figure 41 Showing according to similar Figure 40 One embodiment of the material processing apparatus 320 incorporates an edge grinding stage 332. The material processing apparatus 320 includes a laser processing stage 322, a carrier bonding stage 323, a material breaking stage 324, a first mechanical processor 326, a plurality of parallelly arranged rough grinding stages 328A, 328B, a second mechanical processor 328, a carrier removal stage 331, an edge grinding stage 332, a fine grinding stage 334, and a CMP stage 336. An exemplary edge grinding stage 332 may be arranged to hold a wafer between an upper and lower clamping portion of a turntable, the turntable being arranged close to a rotary polishing tool (e.g., a tool with a concave shape during surface preparation)... Figure 37G (As shown). Clamping the wafer in this manner may unintentionally damage the wafer surface (e.g., the Si-termination surface of a SiC wafer). Therefore, Figure 41 The edge grinding stage 332 shown is positioned upstream of the finishing stage 334 to allow removal of any surface damage caused by the edge grinding stage 332 within the finishing stage 334. While the finishing stage 334 can remove a small degree of wafer thickness, thereby altering the rounded or beveled edge profile produced by the edge grinding stage 332, it will retain a sufficient degree of rounded or beveled edge profile to suppress wafer edge breakage.

[0300] according to Figure 41 The apparatus 320 can be used to perform a method for processing a crystalline material wafer, the crystalline material wafer including a first surface with surface damage thereon, wherein the first surface is defined by edges. The method includes grinding the first surface with at least one first grinding device to remove a first portion of the surface damage; after grinding the first surface with at least one first grinding device, edge grinding is performed on the edges to form a beveled or rounded edge profile; and after edge grinding, the first surface is ground with at least one second grinding device to remove a second portion of the surface damage sufficient to make the first surface suitable for further processing by chemical mechanical planarization. In some embodiments, the first grinding device may be implemented in coarse grinding tables 328A, 328B, edge grinding may be performed by an edge grinding table 332, and the second grinding device may be implemented in a seeking grinding table 312. In some embodiments, a carrier removal step may be performed after grinding the first surface with at least one first grinding device and before edge grinding of the edges to form a beveled or rounded edge profile.

[0301] In some implementations, a protective surface coating may be employed to reduce the likelihood of additional surface damage during edge grinding and to prepare the crystalline material wafer for chemical mechanical planarization. This surface coating may include photoresist or any other suitable coating material, which may be applied before edge grinding and removed afterward.

[0302] Figure 42 It is based on and Figure 40 A schematic diagram of a similar embodiment of the material processing apparatus 340 is shown, but a surface coating stage 354 is integrated between the fine grinding stage 352 and the edge grinding stage 356, and a coating removal stage 358 is integrated between the edge grinding stage 356 and the CMP stage 360. The material processing apparatus 340 also includes a laser processing stage 342, a material fracture stage 344, a first mechanical processor 346, a plurality of parallel-arranged rough grinding stages 348A, 348B, and a second mechanical processor 348 upstream of the fine grinding stage 352. The coating stage 354 can be configured to apply a protective coating (e.g., photoresist) by methods such as spin coating, dip coating, spray coating, etc. The protective coating should have sufficient thickness and robustness to absorb any damage that may occur from the edge grinding stage 365. For SiC wafers, the Si facets can be coated with a protective coating because the Si facets are typically the surfaces on which epitaxial growth is performed. The coating removal stage 358 can be configured to peel off the coating by chemical, thermal, and / or mechanical means.

[0303] according to Figure 42 The apparatus 340 can be used to perform a method for processing a crystalline material wafer, the crystalline material wafer including a first surface with surface damage, the first surface being defined by edges. The method includes grinding the first surface with at least one first grinding apparatus (e.g., coarse grinding stations 348A, 348B) to remove a first portion of the surface damage; then grinding the first surface with at least one second grinding apparatus (e.g., fine grinding station 352) to remove a second portion of the surface damage, sufficient to make the first surface suitable for further processing by chemical mechanical planarization; subsequently forming a protective coating on the first surface (e.g., using a surface coating station 354); then edge grinding (e.g., using an edge grinding station 356) to form a beveled or rounded edge profile; and subsequently removing the protective coating from the first surface (e.g., using a coating removal station). The first surface can then be processed by chemical mechanical planarization (e.g., by a CMP station 360) to prepare the first surface (e.g., the Si end surface of the wafer) for subsequent processing, such as surface cleaning and epitaxial growth.

[0304] In some embodiments, the clamping device may be configured to hold an ingot having an end face that is not perpendicular to its sidewalls, allowing the end face to be laser-processed to create subsurface damage. In some embodiments, the clamping effector may conform to an inclined sidewall having a circular cross-section when viewed from above. In some embodiments, the clamping effector may include a connector that allows the clamping effector to conform to the inclined sidewall.

[0305] Figure 43AThis is a schematic side cross-sectional view of a first clamping device 362 for holding a spindle 364 according to one embodiment, the spindle having end faces 366, 368 that are not perpendicular to its sidewalls 370. The upper end face 366 is horizontally arranged to receive a laser beam 376. The lower end face 368 may have a carrier 372 attached to the lower end face 368, wherein a chuck 374 (e.g., a vacuum chuck) holds the carrier 372. A clamping effector 378 with a non-perpendicular surface is provided to clamp the sidewalls 370 of the spindle 364, wherein the clamping effector 378 is arranged at non-perpendicular angles A1, A2 relative to a horizontal actuating rod 380. As shown, holding the spindle 364 (e.g., near the bottom of the spindle) using the clamping device 362 makes the upper portion of the upper end face 366 and the upper portion of the sidewalls 370 available for processing using the methods disclosed herein.

[0306] Figure 43B This is a schematic side cross-sectional view of a second clamping device 362' for holding a spindle 364' according to one embodiment, the spindle having end faces 366', 368' that are not perpendicular to its sidewalls 370'. The upper end face 366' is horizontally arranged to receive a laser beam 376, while the lower end face 368' may have a carrier 372' connected thereto, the carrier 372' being held by a chuck 374'. A clamping effector 378' with a non-perpendicular surface is provided to clamp the sidewalls 370' of the spindle 364', wherein the clamping effector 378' is arranged at non-perpendicular angles A1, A2 relative to a horizontal actuating rod 380'. A pivot joint 382' is disposed between the actuating rod 380' and the clamping effector 378', thereby facilitating automatic alignment between the clamping effector 378' and the sidewalls 370' of the spindle 364'.

[0307] In one embodiment, a 150mm diameter single-crystal SiC substrate (ingot) with a thickness greater than 10mm is used as the starting material for producing a SiC wafer with a thickness of 355 micrometers. Laser emission irradiates the upper surface of the SiC substrate through the C-terminal junction to create subsurface laser damage. A sapphire carrier is bonded to the upper surface of the SiC substrate using the thermoplastic adhesive material disclosed herein, and thermal fracture is performed to separate the upper (wafer) portion of the SiC from the remainder of the ingot. The Si end faces of the separated wafer portion and the C end faces of the ingot residue are coarsely ground using a 2000-mesh grinding wheel (e.g., a metal, glass, or resin-bonded grinding wheel) to remove all visible laser and fracture damage. Subsequently, the Si end faces of the separated wafer portion and the C end faces of the ingot residue are finely ground using a 7000 or higher grit (e.g., up to 30000 grit or higher) (e.g., using a glass grinding surface) to produce a smoother surface, preferably with an average roughness (R0) of less than 4 nm. a More preferably, in 1-2nm R aWithin a certain range. A smooth surface is required on the ingot residue to avoid any impact on subsequent laser processing. The wafer is prepared for CMP and has sufficient smoothness to minimize the amount of CMP removal required, as CMP is typically a more expensive method. Typical material removal during fine grinding can be in the range of 5 to 10 micrometers in thickness to remove all residual subsurface damage and any remaining laser damage (visible and invisible) from coarse grinding. Subsequently, the ingot residue is returned to the laser for further processing, and the wafer is edge-ground and undergoes chemical mechanical planarization (CMP) to prepare it for epitaxial growth. Edge grinding can be performed between coarse and fine surface grinding to avoid any risk of scratching the finely ground Si surface. Material removal during CMP can be in the range of approximately 2 micrometers in thickness. The total material consumed from the substrate (ingot) can be less than 475 micrometers. Given a final wafer thickness of 355 micrometers, the kerf loss is less than 120 micrometers.

[0308] The technical benefits that can be obtained from one or more embodiments of this disclosure may include: reduced kerf loss of crystalline material compared to wire saw cutting; reduced processing time and increased yield of crystalline material wafers and resulting devices compared to wire saw cutting; reduced laser processing time compared to existing laser-based methods; reduced force required to achieve fracture along the laser-damaged zone; reduced need for post-separation surface smoothing to remove laser damage after separation; reduced bending and fracture of crystalline material; and / or increased reproducibility of thin layers separated from the crystalline material substrate.

[0309] Those skilled in the art will recognize improvements and modifications to the preferred embodiments of this disclosure. All such improvements and modifications are considered to be within the scope of the concepts disclosed herein and the subsequent claims.

Claims

1. A method for processing crystalline materials, comprising: Provide laser emission focused on the interior of the crystalline material of the substrate, and perform relative lateral movement between the laser and the substrate to form subsurface laser damage with a first subsurface laser damage pattern, the first subsurface laser damage pattern comprising a first plurality of substantially parallel lines; as well as After forming the first subsurface laser damage pattern, laser emission focused inside the crystalline material is provided, and relative lateral movement between the laser and the substrate is performed to form subsurface laser damage with a second subsurface laser damage pattern comprising a second plurality of substantially parallel lines; The first laser damage pattern under the first surface forms a first plurality of cracks inside the crystalline material, and the first plurality of cracks extend laterally outward from one of the first plurality of substantially parallel lines. The second surface laser damage pattern forms a second plurality of cracks inside the crystalline material, and the second plurality of cracks extend laterally outward from one of the second plurality of substantially parallel lines; The lines in the second plurality of substantially parallel lines are scattered among the lines in the first plurality of substantially parallel lines; and At least some of the second plurality of substantially parallel lines do not intersect any of the first plurality of substantially parallel lines.

2. The method for processing crystalline materials according to claim 1, wherein, Each of the second plurality of substantially parallel lines does not intersect any of the first plurality of substantially parallel lines.

3. The method for processing crystalline materials according to claim 1 or 2, wherein, Each of the second plurality of substantially parallel lines is arranged between different pairs of adjacent lines in the first plurality of substantially parallel lines.

4. The method for processing crystalline materials according to any one of claims 1 or 2, wherein: The crystalline material comprises a hexagonal crystal structure; and Each of the first plurality of substantially parallel lines and each of the second plurality of substantially parallel lines is perpendicular to the hexagonal crystal structure. Within ±5 degrees of the direction and substantially parallel to the surface of the substrate.

5. The method for processing crystalline materials according to any one of claims 1 or 2, wherein, The spacing between at least some adjacent lines in the first plurality of substantially parallel lines is substantially the same as the spacing between at least some adjacent lines in the second plurality of substantially parallel lines.

6. The method for processing crystalline materials according to claim 1, further comprising: After forming the first and second subsurface laser damage patterns, laser emission focused inside the crystalline material is provided, and a relative lateral movement between the laser and the substrate is performed to form subsurface laser damage with a third subsurface laser damage pattern comprising a third plurality of substantially parallel lines. At least some of the third plurality of substantially parallel lines are scattered between the lines of the first plurality of substantially parallel lines and the second plurality of substantially parallel lines.

7. The method for processing crystalline materials according to claim 6, wherein, Each of the third plurality of substantially parallel lines is arranged between one of the first plurality of substantially parallel lines and one of the second plurality of substantially parallel lines.

8. The method for processing crystalline materials according to any one of claims 6 or 7, wherein, The focal depth of the laser emission within the interior of the substrate is a distance ranging from about 2 micrometers to about 5 micrometers between at least two of the laser damage patterns on the first, second, and third surfaces.

9. The method for processing crystalline materials according to any one of claims 6 or 7, wherein: The second plurality of cracks are not connected to the first plurality of cracks; and The third surface laser damage pattern forms a third plurality of cracks inside the crystalline material. The third plurality of cracks extend laterally outward from one of the third plurality of substantially parallel lines. At least some of the third plurality of cracks are connected to at least some of the first plurality of cracks and at least some of the second plurality of cracks.

10. The method for processing crystalline materials according to any one of claims 6 or 7, wherein: Each of the third plurality of substantially parallel lines is arranged between a corresponding line in the first plurality of substantially parallel lines and a corresponding line in the second plurality of substantially parallel lines to form a three-line group, such that the laser damage patterns under the first, second, and third surfaces combine to form multiple three-line groups; and For one or more of the plurality of three-line groups, the three-line group is separated from at least one adjacent three-line group by an inter-group interval that exceeds the interval between any two adjacent lines in the one or more three-line groups.

11. The method for processing crystalline materials according to any one of claims 6 or 7, wherein: The crystalline material comprises a hexagonal crystal structure; and Each of the first plurality of substantially parallel lines, each of the second plurality of substantially parallel lines, and each of the third plurality of substantially parallel lines are associated with the hexagonal crystal structure. Angles that deviate vertically from the direction by approximately 1 degree to approximately 5 degrees.

12. The method for processing crystalline materials according to any one of claims 6 or 7, wherein, At least some of the first plurality of substantially parallel lines are arranged within the crystalline material at substantially the same depth as at least some of the second plurality of substantially parallel lines.

13. The method for processing crystalline materials according to any one of claims 1 or 2, further comprising: The detection across at least a portion of the surface of the substrate indicates the presence of non-uniform doping conditions in the crystalline material, the non-uniform doping including at least one first doping region and at least one second doping region; and In response to the detection of the condition indicating non-uniform doping of the crystalline material, during the formation of the first subsurface laser damage pattern and the second subsurface laser damage pattern, the laser power is changed to provide laser emission at a first average power when forming subsurface laser damage in the first doped region and to provide laser emission at a second average power when forming subsurface laser damage in the second doped region.

14. The method of any one of claim 1 or 2, further comprising performing a repeating process of at least one of the first subsurface laser damage pattern or the second subsurface laser damage pattern, including providing laser emission focused within the crystalline material to form a repeating subsurface laser damage pattern aligned with at least one of the first subsurface laser damage pattern or the second subsurface laser damage pattern, wherein the repeating subsurface damage pattern is centered at a depth relative to the surface of the crystalline material that is different from at least one of the first subsurface laser damage pattern or the second subsurface laser damage pattern.

15. The method for processing crystalline material according to any one of claims 6 or 7, further comprising performing a repeating process of at least one of a first, second, or third subsurface laser damage pattern, including providing laser emission focused within the crystalline material to form a repeating subsurface laser damage pattern aligned with at least one of the first, second, or third subsurface laser damage patterns, wherein the repeating subsurface damage pattern is centered at a depth relative to the surface of the crystalline material that is different from at least one of the first, second, or third subsurface laser damage patterns.

16. The method for processing crystalline material according to any one of claims 1 or 2, further comprising breaking the crystalline material substantially along at least one of the first subsurface laser damage pattern and the second subsurface laser damage pattern or between the first subsurface laser damage pattern and the second subsurface laser damage pattern to produce first and second crystalline material portions, the first and second crystalline material portions having a reduced thickness relative to the substrate, but having substantially the same length and width as the substrate.

17. A method for processing crystalline materials, comprising: Laser emission is provided that is focused within the interior of a substrate of a crystalline material, and a relative lateral movement is made between the laser and the substrate to form subsurface laser damage with an initial subsurface laser damage pattern comprising an initial plurality of substantially parallel lines; as well as Laser emission is provided and focused within the interior of the substrate, and a relative lateral movement is made between the laser and the substrate to form subsurface laser damage with a subsequent subsurface laser damage pattern comprising a plurality of substantially parallel lines. The lines in the initial plurality of substantially parallel lines are not parallel to the lines in the subsequent plurality of substantially parallel lines. The angular direction of the subsequent plurality of substantially parallel lines differs from the angular direction of the initial plurality of substantially parallel lines by no more than 10 degrees; and At least some of the subsequent substantially parallel lines do not intersect any of the initial substantially parallel lines.

18. The method for processing crystalline materials according to claim 17, wherein, Each of the subsequent plurality of substantially parallel lines does not intersect any of the initial plurality of substantially parallel lines.

19. The method for processing crystalline materials according to any one of claims 17 or 18, wherein, The subsequent plurality of substantially parallel lines are scattered among the lines of the initial plurality of substantially parallel lines.

20. The method for processing crystalline materials according to any one of claims 17 or 18, wherein, Each of the subsequent plurality of substantially parallel lines is arranged between different pairs of adjacent lines in the initial plurality of substantially parallel lines.

21. The method for processing crystalline materials according to any one of claims 17 or 18, wherein, The crystalline material comprises a hexagonal crystal structure, wherein each of the initial plurality of substantially parallel lines and each of the subsequent plurality of substantially parallel lines is perpendicular to the hexagonal crystal structure at a distance of <112. - Within ±5 degrees of the 0> direction and substantially parallel to the surface of the substrate.

22. The method for processing crystalline materials according to claim 17, wherein, One or more of the subsequent substantially parallel lines intersect one or more of the initial substantially parallel lines.

23. The method for processing crystalline materials according to claim 17, wherein: The initial subsurface laser damage pattern includes a first subsurface laser damage pattern and a second subsurface laser damage pattern. The first subsurface laser damage pattern includes a first plurality of substantially parallel lines, and the second subsurface laser damage pattern includes a second plurality of substantially parallel lines. The subsequent laser damage pattern includes a third subsurface laser damage pattern, which comprises a third plurality of substantially parallel lines; and The lines in the third plurality of substantially parallel lines are scattered between the lines in the first plurality of substantially parallel lines and the second plurality of substantially parallel lines, and each line in the third plurality of substantially parallel lines is arranged between one line in the first plurality of substantially parallel lines and one line in the second plurality of substantially parallel lines.

24. The method for processing crystalline materials according to claim 23, wherein, Each of the first plurality of substantially parallel lines is separated from the nearest line of the second plurality of substantially parallel lines by at least 100 micrometers.

25. The method for processing crystalline materials according to any one of claims 23 or 24, wherein, The focal depth of the laser emission within the interior of the substrate is a distance ranging from about 2 micrometers to about 5 micrometers between at least two of the laser damage patterns on the first, second, and third surfaces.

26. The method for processing crystalline materials according to any one of claims 23 or 24, wherein: The first subsurface laser damage pattern includes a first plurality of cracks within the crystalline material, the first plurality of cracks extending laterally outward from one of the first plurality of substantially parallel lines; The second subsurface laser damage pattern includes a second plurality of cracks within the crystalline material, the second plurality of cracks extending laterally outward from one of a second plurality of substantially parallel lines, and the second plurality of cracks are not connected to the first plurality of cracks; and The third surface laser damage pattern includes a third plurality of cracks within the crystalline material, the third plurality of cracks extending laterally outward from a third plurality of substantially parallel lines, wherein at least some of the third plurality of cracks are connected to at least some of the first plurality of cracks and at least some of the second plurality of cracks.

27. The method for processing crystalline materials according to any one of claims 23 or 24, wherein, During the formation of the initial subsurface laser damage pattern and the subsequent subsurface laser damage pattern, the focal depth of the laser emission within the interior of the substrate is substantially the same.

28. The method for processing crystalline materials according to any one of claims 17, 18, 23 or 24, further comprising: The detection across at least a portion of the surface of the substrate indicates the presence of non-uniform doping conditions in the crystalline material, the non-uniform doping including at least one first doping region and at least one second doping region; as well as During the formation of the initial subsurface laser damage pattern and the subsequent subsurface laser damage pattern, in response to the detection of conditions indicating non-uniform doping of the crystalline material, the laser power is changed to provide laser emission at a first average power when forming subsurface laser damage in the first doped region, and to provide laser emission at a second average power when forming subsurface laser damage in the second doped region.

29. The method for processing crystalline materials according to any one of claims 17, 18, 23 or 24, wherein, The crystalline material includes single-crystal semiconductor materials.

30. The method of processing crystalline material according to any one of claims 17, 18, 23 or 24, further comprising breaking the crystalline material substantially along at least one of the initial subsurface laser damage pattern and the subsequent subsurface laser damage pattern or between the initial subsurface laser damage pattern and the subsequent subsurface laser damage pattern to produce a first crystalline material portion and a second crystalline material portion, each having a reduced thickness relative to the substrate, but having substantially the same length and width as the substrate.

31. The method for processing crystalline materials according to claim 30, wherein, At least one of the first crystalline material portion or the second crystalline material portion includes a freestanding wafer configured to grow at least one epitaxial layer thereon.

32. The method for processing crystalline materials according to claim 30, wherein, One of the first crystalline material portion or the second crystalline material portion includes a device wafer, the device wafer including at least one epitaxial layer grown thereon.

33. A method for processing a crystalline material, the crystalline material comprising a plurality of regions that do not overlap with each other, the method comprising: A first plurality of subsurface laser-damaged zones are formed in each of the plurality of regions of the crystalline material; In each of the plurality of regions of the crystalline material, a second plurality of subsurface laser-damaged regions are formed, wherein at least some of the first plurality of subsurface laser-damaged regions do not intersect with the subsurface laser-damaged regions of the second plurality of subsurface laser-damaged regions, wherein the first plurality of subsurface laser-damaged regions comprise a first plurality of substantially parallel lines, and the second plurality of subsurface laser-damaged regions comprise a second plurality of substantially parallel lines; as well as Performing a repetitive process of forming at least one of the first plurality of subsurface laser-damaged regions or the second plurality of subsurface laser-damaged regions in each of the plurality of regions of the crystalline material includes providing laser emission focused inside the crystalline material to form a repetitive subsurface laser-damaged region aligned with at least one of the first plurality of subsurface laser-damaged regions or the second plurality of subsurface laser-damaged regions, wherein the repetitive subsurface laser-damaged region is centered at a depth relative to the surface of the crystalline material that is different from at least one of the first plurality of or the second plurality of laser-damaged regions.

34. The method according to claim 33, wherein, Each of the second plurality of substantially parallel lines does not intersect any of the first plurality of substantially parallel lines.

35. The method according to any one of claims 33 or 34, further comprising: After forming the first plurality of subsurface laser-damaged regions and the second plurality of subsurface laser-damaged regions, a third plurality of subsurface laser-damaged regions are formed in each of the plurality of regions of the crystalline material, wherein: The third plurality of subsurface laser-damaged regions comprise a third plurality of substantially parallel lines; and At least some of the third plurality of substantially parallel lines are scattered between the lines in the first plurality of substantially parallel lines and the lines in the second plurality of substantially parallel lines.

36. The method of claim 35, wherein: The first plurality of subsurface laser-damaged regions include a first plurality of cracks within the crystalline material, the first plurality of cracks extending laterally outward from one of the first plurality of substantially parallel lines; and The second plurality of subsurface laser-damaged regions include a second plurality of cracks within the crystalline material, the second plurality of cracks extending laterally outward from one of the second plurality of substantially parallel lines.

37. The method according to claim 33, wherein, The repeated process of forming at least one of the first plurality of subsurface laser-damaged regions or the second plurality of subsurface laser-damaged regions in each of the plurality of regions of the crystalline material includes: The process of forming the first plurality of subsurface laser-damaged regions and the second plurality of subsurface laser-damaged regions in each of the plurality of regions of the crystalline material is repeated.

38. A method for processing a crystalline material, the crystalline material comprising a plurality of regions that do not overlap with each other, the method comprising: A first plurality of subsurface laser damage regions and a second plurality of subsurface laser damage regions are sequentially formed in each of the plurality of regions to form a dispersed subsurface laser damage region, wherein at least some of the first plurality of subsurface laser damage regions do not intersect with the subsurface laser damage regions of the second plurality of subsurface laser damage regions; as well as After forming the first plurality of subsurface laser-damaged regions and the second plurality of subsurface laser-damaged regions, a third plurality of subsurface laser-damaged regions are formed in each of the plurality of regions of the crystalline material; The first plurality of subsurface laser-damaged regions comprise a first plurality of substantially parallel lines, the second plurality of subsurface laser-damaged regions comprise a second plurality of substantially parallel lines, and the third plurality of subsurface laser-damaged regions comprise a third plurality of substantially parallel lines; and At least some of the third plurality of substantially parallel lines are scattered between the lines of the first plurality of substantially parallel lines and the lines of the second plurality of substantially parallel lines.

39. The method according to claim 38, wherein, Each of the second plurality of substantially parallel lines is arranged between different pairs of adjacent lines in the first plurality of substantially parallel lines.

40. The method according to any one of claims 38 or 39, wherein, The multiple regions include at least three regions.

41. A method for processing crystalline materials, comprising: Laser emission is provided, focused at an initial depth within the interior of a crystalline material substrate, and a relative lateral movement is made between the laser and the substrate to form subsurface laser damage, the subsurface laser damage having an initial subsurface laser damage pattern substantially centered at the initial depth within the interior, the initial subsurface laser damage pattern comprising a first plurality of substantially parallel lines; as well as Laser emission is provided, focused at a subsequent depth within the interior of the crystalline material, and a relative lateral movement is made between the laser and the substrate to form subsurface laser damage having a subsequent laser damage pattern substantially centered at the subsequent depth within the interior, the subsequent laser damage pattern comprising a second plurality of substantially parallel lines, wherein the subsequent depth differs from the initial depth, the subsequent subsurface laser damage pattern is substantially aligned with the initial subsurface laser damage pattern, and at least a portion of the vertical extent of the subsurface laser damage of the initial subsurface laser damage pattern overlaps with at least a portion of the vertical extent of the subsurface laser damage of the subsequent subsurface laser damage pattern, wherein the lines of the second plurality of substantially parallel lines do not intersect the lines of the first plurality of substantially parallel lines.

42. The method for processing crystalline materials according to claim 41, wherein, The difference between the initial depth and the subsequent depth is in the range of about 2 micrometers to about 5 micrometers.

43. The method for processing crystalline materials according to any one of claims 41 or 42, wherein: The crystalline material comprises a hexagonal crystal structure; and Each of the first plurality of substantially parallel lines and each of the second plurality of substantially parallel lines is perpendicular to the hexagonal crystal structure at <112. - Within ±5 degrees of the 0> direction and substantially parallel to the surface of the substrate.

44. The method for processing crystalline materials according to any one of claims 41 or 42, wherein, One or more of the second plurality of substantially parallel lines intersect one or more of the first plurality of substantially parallel lines.

45. The method for processing crystalline materials according to any one of claims 41 or 42, wherein: The lines in the first plurality of substantially parallel lines are not parallel to the lines in the second plurality of substantially parallel lines.

46. ​​The method for processing crystalline materials according to any one of claims 41 or 42, wherein, Each of the first plurality of substantially parallel lines is separated from the nearest line of the second plurality of substantially parallel lines by at least 100 micrometers.

47. The method for processing crystalline materials according to any one of claims 41 or 42, further comprising: The detection across at least a portion of the surface of the substrate indicates the presence of non-uniform doping conditions in the crystalline material, the non-uniform doping including at least one first doping region and at least one second doping region; and During the formation of the initial subsurface laser damage pattern and the subsequent subsurface laser damage pattern, in response to the detection of conditions indicating non-uniform doping of the crystalline material, the laser power is changed to provide laser emission at a first average power when forming subsurface laser damage in the first doped region, and to provide laser emission at a second average power when forming subsurface laser damage in the second doped region.

48. The method for processing crystalline materials according to any one of claims 41 or 42, wherein, The crystalline material includes single-crystal semiconductor materials.

49. The method for processing crystalline materials according to any one of claims 41 or 42, wherein: The lines in the first plurality of substantially parallel lines are not parallel to the lines in the second plurality of substantially parallel lines; and The lines in the second plurality of substantially parallel lines are separated from the lines in the first plurality of substantially parallel lines by no more than 10 degrees in orientation.

50. The method of processing crystalline material according to any one of claims 41 or 42, further comprising breaking the crystalline material substantially along at least one of the initial depth and the subsequent depth or between the initial depth and the subsequent depth to produce a first crystalline material portion and a second crystalline material portion, each of the first crystalline material portion and the second crystalline material portion having a reduced thickness relative to the substrate, but having substantially the same length and width as the substrate.

51. The method for processing crystalline materials according to claim 50, wherein, At least one of the first crystalline material portion or the second crystalline material portion includes a freestanding wafer configured for growing at least one epitaxial layer thereon.

52. The method for processing crystalline materials according to claim 50, wherein, One of the first crystalline material portion or the second crystalline material portion includes a device wafer, the device wafer including at least one epitaxial layer grown thereon.

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